antenna system planning

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Reference Classification: 900 000File Name: Ant_SystPl_ed01.doc Save Date: 2003-05-06 Revision Number: 008

3DF 01902 2711 VAZZA Edition 01 RELEASED CONFIDENTIAL 1/64

Professional Customer ServicesRadio Network Planning Expert CenterNetwork Planning

GSM B7

Methods

Antenna

Guideline

GSM, UMTS, antenna type selection, feeder length planning, TMA planning, tilt planning, diversity planning,mounting clearance,antenna separation, antenna pattern, A955, EMC

2003-Apr-29

E. SCHNEIDER (LUDWIGSBURG)

Antenna System PlanningAbstract

This document summarizes previously written documents on antenna engineering andemphasizes the key engineering issues.

Domain

Product

Division

Rubric

Type

Keywords

Release Date

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2/64 CONFIDENTIAL Edition 01 RELEASED 3DF 01902 2711 VAZZA

Predistribution

PCS/NPL/Methods M.Hahn PCS/RNE B. PayerPCS/NPL/Tools V. Stuhr ACS/PS (ND) K. DanielPCS/RNE K.HeinleinPCS/RNE FJ.KleinPCS/RNE R. SchwarzPCS/RNE S. Hosseyni

Appraisal and Approval Authorities

Department Name Date Signature

MND/BU-MRA/PCS C. Brechtmann

PCS/NPL/Methods M. Hahn

PCS/RNE K. Heinlein

Distribution List

PCS (IDDL_Default)

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Contents

SCOPE .............................................................................................................................................................4

REFERENCED DOCUMENTS...............................................................................................................................5

RELATED DOCUMENTS AND INTERNET LINKS ....................................................................................................5

1 DOCUMENT OVERVIEW .................................................................................................................................6

2 RULES FOR ANTENNA PLANNING ..................................................................................................................62.1 Selection of antenna type .............................................................................................................................62.2 Planning antenna feeder length..................................................................................................................122.3 Planning TMA usage for GSM.....................................................................................................................142.4 Antenna height planning............................................................................................................................182.5 Planning the antenna azimuth ....................................................................................................................202.6 Downtilt planning ......................................................................................................................................202.7 Antenna diversity planning .........................................................................................................................252.7.1 Rx Diversity gain .....................................................................................................................................262.7.2 Rx space diversity ....................................................................................................................................272.7.3 Polarization diversity................................................................................................................................282.7.4 GSM space and polarization diversity on UL .............................................................................................302.7.5 Further rules on diversity..........................................................................................................................302.7.6 UMTS-FDD Tx diversity ............................................................................................................................312.7.7 UMTS FDD 4-RX diversity on UL...............................................................................................................342.8 Intra-system and inter-system compatibility assessment for site sharing ..........................................................362.8.1 How to ensure the intra-system and inter-system compatibility? ..................................................................382.9 EMC impact on antenna system planning....................................................................................................432.10 RNP tool related aspects on antenna planning ...........................................................................................43

3 RULES FOR ANTENNA INSTALLATION ...........................................................................................................443.1 Mounting rules for tower, mast, roof, wall mounting of antennas ...................................................................443.1.1 Side mounting of omni macro antennas on mast/ tower ............................................................................443.1.2 Minimum macro antenna height mounting for roof top.............................................................................453.1.3 Maximum skew angle for wall mounting of directional macrocell antennas .................................................463.1.4 Microcell antenna mounting rules ............................................................................................................463.2 Spacing for single band antennas in dual band GSM900/GSM1800 scenario................................................473.3 Tilt angle implementation ...........................................................................................................................473.4 Azimuth angle implementation ...................................................................................................................47

ABBREVIATIONS ..............................................................................................................................................48

INDEX.............................................................................................................................................................49

APPENDIX A FREQUENCY BANDS ................................................................................................................50

APPENDIX B ANTENNA TYPES .....................................................................................................................51

APPENDIX C ANTENNA SYSTEMS OPTIONS..................................................................................................52

APPENDIX D OVERVIEW ON ANTENNA DOWNTILT ......................................................................................53

APPENDIX E OVERVIEW ON ANTENNA DIVERSITY........................................................................................54

APPENDIX F PRINCIPLE OF AIR COMBINING................................................................................................58

APPENDIX G ANTENNA PATTERN DISTORTION FOR DIFFERENT MOUNTING SCENARIOS ...........................58

APPENDIX H INTRA-/INTER-SYSTEM COMPATIBILITY......................................................................................61

APPENDIX I MISCELLANEOUS.....................................................................................................................63

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SCOPE

The target group is: engineers planning GSM radio networks.

This document summarizes previously written documents on antenna engineering andemphasizes the key engineering issues.

The main focus of this document lies on antenna engineering for GSM networks.Where applicable, the considerations were extended for UMTS.

Not in the scope of the document edition 01 are: indoor and repeater application,smart antennas, inter-system compatibility issues.

Please send your comments, update wishes referring to this document [email protected]. They will be considered in a next edition of the document.

To get into contact with the Radio Network Planning Expert Center on antennatopics, please use the intranet link of Professional Customer Services underhttp://aww-mnd.alcatel.de/pcs/Antennas.

Readership Profile

Content Summary

Service Information

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REFERENCED DOCUMENTS

[1.1] 3DF 00995 000 PGZZA Antenna Engineering Rules[1.2] Memo Use of TMA for G3/G4 BTS in GSM1800[1.3] Technical Sheet TMA for UMTS[1.4] 3DF 01902 2011 VAZZA Using GSM900 High Power TRX[1.5] 3DC 21150 0263 TQZZA GSM 900, GSM 1800 Use of High power TRX with

TMA (white paper)[1.6] 3DF 01903 2711 VAZZA TMA configurations for GSM and impact on

network design[2.1] 3BK 10023 0001 DSZZA Aspects on Polarization Diversity[2.2] Memo Considerations of Cross Polarized Antennas for

Radio Network Planning[2.3] Memo Performance of Cross Polarized Antennas in Rural

Areas (summary of dipl. thesis, Sept 1999)[3] 3DF 00995 0000 DSZZA Physical Specification of Standard Antenna Set[4.1] 3DC 20008 0001 UZZZA Hardware commercial configurator for antenna

systems[4.2] 3DC 20008 0003 UZZZA Content of Saleable Items for Antenna Systems[5.1] 3DC 21019 0005 TQZZA Site Sharing GSM-UMTS Rf Aspects (version 04)[6.1] ND Design Paper DL Analysis Tx Diversity[6.2] TD Memo Transmit diversity in UTRA/FDD[6.3] Technical Sheet 4-Ways Rx Diversity for UMTS[7.1] Memo Enhanced Diversity with G4 TRE[7.2] Memo BTS cell split[7.3] 3DC 21144 0024 TQZZA FFD: Cell split over 2 BTSs in Release B7[7.4] Memo GSM product range[7.5] 3DC 20001 0010 UZZZA Hardware Commercial Configurator for

EVOLIUM™ A9100 Base Station[7.6] 3DC 20001 0014 UZZZA Hardware Commercial Configurator for

EVOLIUM™ A910 Micro-BTS[7.7] 3DC 21083 0001 TQZZA EVOLIUM™ A9100 BTS Product description[7.8] 3DC 21083 0003 TQZZA EVOLIUM™ A910 µ BTS Product description[8] ed 02, draft Dual Band Network Engineering; Network Design,

Planning and Operational Aspects[9] 3DF 00983 1050 DSZZA Consideration of antenna diagrams A955 (V5, V6)[10] William C.Y. Lee Mobile Cellular Telecommunications Systems

RELATED DOCUMENTS AND INTERNET LINKS

[A 1] Antenna Data Sheet database; consistent with [4.2]http://aww.stgl.sel.alcatel.de/pub/mcd/mps/ant/index.htm

[RFS 1] Application note APN008: Isolation/Co-siting, Oct 00,http://www.rfsworld.com

[RFS 2] RFS white paper: Using continuously adjustable electricaldowntilt antennas to optimize wireless networks, Feb 01

[RFS 3] Celwave Antenna datasheets and patternshttp://selldoc.rfsworld.com/IndoorDocs/Mobile%20Communication%20Antenna%20Systems/Antennas/

[KAT 1] Memo (Kathrein) The influence of reflections on radiationpatterns

[KAT 2] Kathrein antenna datasheets and patternshttp://www.kathrein.de/de/mca/produkte/index.htm

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1 DOCUMENT OVERVIEW

Main tasks of the document edition 01 are to give rules for:

? antenna planning (ch. 2)

? antenna installation (ch. 2.9)

Additional background information is given in the document annex on differentantenna topics: frequency bands, antenna types, antenna systems options, downtilt,diversity, air combining, pattern distortions and interference mechanisms.

General remark: throughout this document, GSM900 stands for P-GSM900 if notexplicitly stated; issues related to E-GSM900 are clearly marked.

2 RULES FOR ANTENNA PLANNING

This chapter gives rules for the selection of antenna type, feeder length planning, TMAplanning, antenna height and azimuth planning, downtilt planning, diversity planning.

2.1 Selection of antenna type

This chapter gives rules for the selection of antenna type for different application cases:macro/microcell, single/dual/triple band. General info on antenna types can be foundin APPENDIX B .

The Alcatel saleable antenna items described in [4.1], [4.2] and [A1] must bepreferably selected by radio network planning to the maximum possible extent tominimize the number of different antennas in Alcatel offers/projects; they are based onthe specification given in [3] for

? single band (GSM850, P-GSM9001, GSM1800, GSM1900, UMTS),

? dual band (P-GSM900/GSM1800, GSM850/GSM1800, GSM850/GSM1900, P-GSM900/UMTS, GSM1800/UMTS)

? broadband (GSM1800 /UMTS)

? triple band (GSM900/GSM1800/UMTS)

Remarks to dual band:

? BSS software release B7.2 only supports the combinations P-GSM900/GSM1800,GSM850/GSM1800 and GSM850/GSM1900; currently there is no marketdemand for GSM900/GSM1900.

? the frequency combination GSM1900/UMTS is covered by broadband antennas

General rule:

It is recommended to select the same antenna type +antenna feeder for all sectors of asite. This minimizes the logistic effort for antennas, feeders mounting kits, clamps, etc.but also reduces the risk of installation errors .

Reminder: for a given frequency band, the radome length decreases with increasingvertical HPBW; for a given vertical HPBW, the radome length decreases with increasingfrequency band.

Depending on the application environment the general antenna selection rules of Table1, Table 2, Table 3 apply. The table contains standard antennas which can handlemost of applications. The antennas are recommended for usage in air combiningconfiguration.To select the right downtilt for the antenna, the downtilt planning must be done first,see chapter 2.6.

1 the P-GSM 900 antenna specification can hold also for E-GSM 900

Single band macrocellapplication

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GSM 850/GSM 900Morphoclass Horiz.

HPBW [°]Vert.HPBW [°]

Gain [dBi] El. Tilt [°] Polarization Ant. size[m]

Remarks

dense urban, urban 65 ˜ 6.5 =17 6 Xpol =2.5 165 9 =16.5 6 Xpol =2.0

suburban 90 7-8.5 =16 2-6 Xpol =2.6 2rural 90 7-8.5 =16 2-6 vert. =2.0 2, 3

360 ˜ 7 11 2 vert. 4highway coverage 65 7-8.5 =17 6 vert. =2.5 5

33 =18 0 vert.

Table 1: GSM 850/GSM 900; Key parameters for macrocell single band antenna

GSM 1800/GSM 1900Morphoclass Horiz.



Remarks

dense urban, urban 65 ˜ 6.5 =17 6 Xpol ˜ 1.3suburban 90 7-8.5 =16 2-6 Xpol ˜ 1.3 2rural 90 7-8.5 =16 2-6 vert. ˜ 1.3 2, 3

360 ˜ 7 11 2 vert. 4highway coverage 65 7-8.5 =17 6 vert. ˜ 1.3 5

33 =18 0 vert.

Table 2: GSM 1800/GSM 1900; Key parameters for macrocell single band antenna

UMTSMorphoclass Horiz.



Remarks

dense urban, urban 65 ˜ 6.5 =17 V 0-8 Xpol ˜ 1.3 6suburban 90 7-8.5 =16 V 0-8 Xpol ˜ 1.3 2, 6rural 90 7-8.5 =16 V 0-8 vert. ˜ 1.3 2, 3, 6, 7

360 ˜ 7 11 V 0-8 vert. 4, 6highway coverage 65 7-8.5 =17 V 0-8 vert. ˜ 1.3 5 ,6

33 =18 V 0-8 vert. 6

Table 3: UTMS; Key parameters for macrocell single band antenna

The following notation is used:

? For the downtilt: 2° means a fix electrical tilt of 2°; 2-6 means a fix electrical tilt inthe range 2°-6°; V 0-8 means a variable electrical tilt in the range 0°-8°.

? for the gain: =16 dBi, means minimum 16 dBi ; it must be the maximum offeredin this category (while freezing the rest of parameters).

Remarks:

1. The recommended antenna type for coverage reasons is the one with themaximum gain offered in this category. But this may not be acceptable by theoperator for dense urban, urban environment if its height > 2 m. If this is thecase the antenna with =2.0 m must be considered whith less gain.For dense urban (high density areas), urban: the coverage between sectors with65° antennas is achieved by increased scattering in these environments.

2. For suburban, rural: the cell overlap with 90° antennas between the sectors isusually sufficient to allow successful handovers.

3. Same standard antenna as for suburban, but cross polar antenna usage is notrecommended, prefer using single polarized antennas and space diversity (seech. 2.7).

4. In rural areas: as an alternative, omni antennas can be used, but consider thepros and cons mentioned in APPENDIX B .

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5. Two solutions exist, depending on the type of the roadway arrangement:

• preferred: same 65° antenna as for dense urban but vertical polarized. Ifnecessary, according to the current morphoclass, uptilt must be applied toget the desired cell range.

• for exceptional cases or straight, rectilinear highway: 33° narrow beamantenna (Remark: two side by side coupled antennas of series AP 9065*(RFS) also lead to 33° horizontal HPBW for highway coverage)

6. For UMTS, analogue parameters as for the lower frequency bands, but with V0°-8° variable electrical tilt; reasons for the variable electrical tilt:a.) to be future proof for the remote tilt option, see APPENDIX D .b.) due to commercial reason: same price expected from preferred antennasuppliers.

7. Currently UMTS is not foreseen to be deployed in rural areas; however, for theopposite case, the same recommendation is valid as for the other bands.

Influence of cell split feature on antenna selection for monoband sites

If e.g. a 3x8 TRX monoband site is realized with the B7 feature “cell split over 2 BTS’s”(see [7.7]), the same antenna type and the same antenna numbers must be selectedfor each BTS rack, else the measured BCCH promises coverage in areas, what cannotbe held by the TRX covering the other area.

In the GSM850, GSM900, GSM1800, GSM1900 and UMTS bands, the antennasspecified in Table 4 can handle most of applications. The range of the parameters isdue to the fact, that the visual impact of the micro antenna has a higher influence onthe antenna selection then its electrical properties.

Horizontal HPBW Vertical HPBW GainOmni 360° 60° ± 20° 5 dBi ± 3 dBSector 85° ± 20° 65° ± 20° 8 dBi ± 3 dB

Table 4: Key parameters for microcell single band outdoor antenna

Micro antenna selection rules:

? For crossroad scenario with symmetrical streets or asymmetrical streets, use omniantenna; a sector antenna can be used as an additional option for crossroadscenario with asymmetrical streets.

? For in-street scenario, wall mounting:

• for coverage in 2 opposite directions: use bi-directional antenna

• for coverage in 1 direction: use directional antenna

? For the Alcatel Evolium A910 µBTS in

• low-loss configuration with air combining: the external sector antennasshould be cross polarized.

• single antenna configuration: the external sector antenna is verticalpolarized

Remark: the internal integrated antenna of the Alcatel Evolium A910 µBTS matches thespecified values of Table 4; its parameters are: Horizontal HPBW > 80°, Vertical HPBW= 65°±15°, Gain > 6.3 dBi, cross polarized, isolation between the 2 polarizationbranches > 25 dB; see the A910 product description [7.8].

In a GSM900/GSM1800 dual band scenario, independent whether it is implementedwith

? co-located single band cells (dual BCCH)

? or multiband cell (single BCCH)

Single band microcell outdoorapplication

900/1800 macrocell dual bandapplication

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it is basically possible to use 3 technical solutions for antenna implementation:

? solution 1: dual band antennas with variable electrical downtilt for each band

? solution 2: single band antennas

? solution 3: dual band antennas with fixed electrical downtilt

For the multiband cell the separate modification of the downtilt is a key instrument totune the fieldstrength level difference between the 900 and 1800 bands to the valuesexpected by the HO algorithms of B6/B7.

The main criteria for selection among the above mentioned solutions is the coveragetarget; Table 5 makes a preference ranking for the solutions; for further details seeTable 6 which gives a comparison of single band antennas vs. dual band antennasbased on the implementation in Alcatel Evolium BTS shown in Figure 1.

nb. TRX in 900 band nb. TRX in 1800 band Preference of solutionslow high 1 > 2 >3multiband BSS

(dual BCCH) other cases 1 = 2 =3low high 1 >> 2 > 3multiband cell

(single BCCH) other cases 1 = 2 = 3

Table 5: Preference ranking of antenna solutions for dual band (assumption: preferred band=1800)

dual band antennas (solution 1, 3) single band antennas (solution 2)+ better suitability for multiband cell operation – not suitable for multiband cell (accurate

identical azimuth setting required in 900 and1800 is more difficult to achieve)

– not ideal for coverage optimisation (separateelectrical but no separate mechanical tilt possiblein solution 1)

+ better for coverage optimization due toseparate mechanical downtilt for 900 and 1800(separate azimuth is possible but doesn’trepresent a real advantage due to the goal toachieve a maximum overlap in 900/1800)+ separate antenna configuration planning forboth bands possible, e.g. 4 TRX in 900 (BTSstandard configuration wired to one crosspolar900 antenna) and 4 TRX in 1800 (BTS low lossconfiguration with air combining)

0 same number of feeders, (expensive costs for feeders, clamps and their installation can bereduced by diplexer usage; diplexer impact on coverage =1dB loss)+ need of 2 external diplexers (if the dual bandantenna has 2 internal diplexers inside theradome)

– need of 4 external diplexers

+ twice less antennas (visual impact) – twice more antennas (visual impact)

– higher antenna price; dual band antenna price> sum of 900+1800 antenna prices(subject to commercial conditions)

+ lower antenna price; sum of 900+1800antennas< dual band antenna price(solution 2 is especially cheaper if initial antennacan be reused after migration from single todual band operation)

+ somewhat lower total cost for the siteincluding hardware (antennas, cable, clamps)and installation labour

– somewhat higher total cost for the siteincluding hardware (antennas, cable, clamps)and installation labour– twice more weight and wind load– higher pole required for vert. separation resp.more mounting space for horiz. separation

Legend: + advantage; – drawback for the solution; 0 equal rating

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Table 6: Comparison of single band antennas vs. dual band antennas

Figure 1: Dual band antenna solution (here with integrated diplexer in the antenna) and single band antennas solution for Alcatel EvoliumBTS

Remarks to Table 5, Table 6:

? The conclusions of Table 6, Table 5 mainly apply for the single operator case (1operator colocates on a site 2 systems in GSM 900, GSM 1800).For the multioperator case, mainly solution 2 is applicable. But if there are EMC ormounting constraints imposed by local authorities, than operators may be forced tocooperate and make an antenna sharing with solution 1 or 3.

? Solution 1: main advantages are separate electrical tilt tuning and better suitabilityfor multiband cell operation; especially when used in a multiband cell with highQoS (CSR, CDR, HSR etc.) requirements and higher TRX number in the preferredband (e.g. 2x900+6x1800), solution 1 is the only recommended(the reason: in the multiband cell the intra-zone HO outer=>inner (900=>1800) is donewith B7.2 HO cause13, which is based only on the outer zone level and –in B7-on the trafficbalance between outer/inner zone; in cases with higher TRX number in the preferred band,MS’s will be often pushed in the inner zone to keep the load balance condition of cause 13,but this can lead to bad QoS if there is no perfect overlap of the inner and outer zones; withsolution 1, the risks of solution 2 - like mismatching azimuths or non-clearance in the nearfield of one of the single band antennas- is eliminated; see [8])

? Solution 2: main advantage is the individual mechanical tilt tuning; this advantageespecially is relevant for high QoS requirements (CSR, CDR, HSR etc.) for co-located single band cells or multiband cell.

? Solution 3: is a tradeoff for cases where the QoS requirements can be met withfixed down-tilts and especially fixed delta between GSM900 and GSM1800fieldstrength level (cf. [8])

Antenna selection rules for the 900/1800 dual band macrocells:

Depending on the application environment the general antenna selection rules of Table7 apply for dual band antennas cf. solution 1 (for the selection of single bandantennas cf. solution 2, refer to Table 1, Table 2).Table 7 contains antennas which can handle most of applications. The parameters arevalid for both bands; the electrical tilt is variable and band independent.

XX

Diplexer Diplexer

Tx/Rx/Rxdiv Tx/Rx/Rx div900 MHz

Evolium BTS


Tx/Rx/Rxdiv 900+1800 Tx/Rx/Rxdiv 900+1800

Tx/Rx/Rxdiv 900+1800


X900

Evolium BTS


X1800

Diplexer

Diplexer

Diplexer

Diplexer


XX

Diplexer Diplexer


Evolium BTS



XX

Diplexer Diplexer


Evolium BTS





X900

Evolium BTS


X1800

Diplexer

Diplexer

Diplexer

Diplexer



X900X

900

Evolium BTS


X1800

X1800

DiplexerDiplexer

DiplexerDiplexer

DiplexerDiplexer

DiplexerDiplexer


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900/1800, 900/UMTS, 1800/UMTS, 850/1800, 850/1900Morphoclass Horiz.


Gain[dBi]

El. Tilt[°]

Polarization Diplexer in theradome

Remarks

dense urban, urban 65 ˜ 7.5 =17 V 0-8 XXpol yes 1suburban 90 ˜ 7.5 =16 V 0-8 XXpol yes 2, 3rural 90 ˜ 7.5 =16 V 0-8 vert. no 4, 5, 6highway coverage 65 ˜ 7.5 =17 V 0-8 vert. no 7

33 =18 V 0-8 vert. no

Table 7: Key parameters for macrocell dual band antenna

The following notation is used:

? for the gain: =16 dBi, means minimum 16 dBi ; it must be the maximum offeredin this category (while freezing the rest of parameters).

? for the downtilt, V0°-8°T means a variable electrical downtilt in the range 0°-8°.

Remarks:

1. For dense urban (high density areas) and urban: the coverage between sectors isachieved by increased scattering in these environments.

2. For suburban, rural: the cell overlap between the sectors is usually sufficient to allowsuccessful handovers.

3. A XXpol 90° antenna is recommended, but currently not offered by the Alcatelpreferred antenna suppliers; e.g. Kathrein plans its market introduction for 3 Q 2003.

4. Same standard antenna as for suburban, but cross polar antenna usage is notrecommended, prefer using single polarized antennas and space diversity (see ch. 2.7)

5. In rural areas: a standard omni dual band antenna is not specified due to its lowmarket penetration, cf. APPENDIX B .

6. Currently UMTS is not foreseen to be deployed in rural areas.

7. In many projects, dual band coverage is planned for highway coverage only inexceptional cases; instead single band coverage is done.

? If enough frequencies are available in the 900 band, typically this band is useddue to its better coverage.

? If (typically) more frequencies are available in 1800 band than in 900, than thisband is used due to the higher capacity which can cope with the total traffic.

However, if it is desired to have dual band coverage, two solutions exist, depending onthe type of the roadway arrangement:

? preferred: same 65° antenna as for dense urban but vertical polarized. The tiltsmust be carefully tuned in both bands to get a matching coverage overlap.

? for exceptional cases or straight, rectilinear highway: 33° narrow beam antenna; itis currently not offered by the Alcatel preferred antenna suppliers;

Rule for diplexer usage: diplexer usage is recommended, since:

? it is cheaper to install external diplexers (at BTS side) and possibly at antennaconnector side (if not already incorporated in the antenna radome) than to install asecond feeder pair

? at migration single => dual band, the old feeder system can be kept if the cablelosses in the new band are still in the allowed range, i.e. =3 dB (see ch. 2.2).

Influence of cell split feature on antenna selection for multiband cell (single BCCH)

If e.g. a 3x(4+4) TRX multiband cell is realized with the B7 feature “cell split over 2BTS’s” (see [7.7]), by doing a migration from multiband BSS (dual BCCH), thepreviously installed antennas of the multiband BSS solution can be kept unchanged.

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For parameters see Table 7.

For parameters see Table 7. Broadband antenna shall be selected only if commerciallyrequired (if cheaper).

For parameters see Table 7. However, market availability strongly depends on theproject demands.

In many projects dual band microcell coverage is rather an exception. If (typically)more frequencies are available in 1800 band than in 900, than this band is used forsingle band coverage due to the higher capacity which can cope with the total traffic.

As mentioned in the subchapter “Single band microcell outdoor application”, the visualimpact of the µ antenna has a higher influence on the antenna selection than itselectrical properties. So, deviations from the standard antenna parameters mentionedbelow are possible.Often, antenna manufacturers offer broadband µ antennas instead of dual band µantennas, which cover the whole band from GSM850 to UMTS.

The specified values of Table 4 are valid and hold for both bands. However, the sectorantenna for the in-street scenario is cross polarized (XXpol) in both bands.

A triple band sector antenna for this case is defined by the parameters for all 3 bands:HPBW 65° (horizontal), 7.5° (vertical), gain 17 dBi, V0°-8 ° T variable and bandindependent electrical tilt, cross polarized (XXXpol) in all bands

This is not a standard antenna, as it covers only a small application range.

see subchapter “900/1800… microcell outdoor dual band application”

2.2 Planning antenna feeder length

This chapter gives rules for feeder length dimensioning and feeder selection andillustrates them with practical examples.

Exemplary feeder types used in Alcatel projects and their loss characteristics are givenin Table 8.To retrieve these and further characteristics (e.g. bending radius), refer to themanufacturers catalogue.

Losses in dB/100mCable Typeseries

Diameter Supplier900 MHz 1800 MHz 2200 MHz

LCF 12-50 1/2” 6.80 9.91 11.10LCF 78-50 7/8” 3.87 5.73 6.44LCFS 114-50 1 1/4” 2.77 4.15 4.68LCF 158-50 1 5/8”

RFS

2.34 3.57 4.05Table 8: Typical feeder types and losses in dB/100m, exemplary for Cellflex Low-Loss Foam-Dielectric Coaxial Cable (RFS)

Jumper cables have to be provided at the points A, B, C along the feeder path ofFigure 3. Table 9gives the jumper cable configuration for sites with and without TMA;the number of jumpers is per feeder, i.e for a single band crosspolar antenna fed by 2cables, the number of jumpers must be multiplied by 2 (see figure in APPENDIX C ).

900/UMTS, 1800/UMTSmacrocell dual band application

1800/UMTS macrocellbroadband application

850/1800, 850/1900 macrocelldual band application

900/1800,850/1800,850/1900,900/UMTS,1800/UMTS microcell

outdoor dual band application

Triple band macrocellapplication

Triple band microcell outdoorapplication

Feeder characteristics

Jumper configuration

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Feeder cable type Jumper cable type Jumper per feeder Jumper per feeder on TMA sitesLCF 12-50 0 * 1 *LCF 78-50 2 3LCFS 114-50 2 3LCF 158-50

LCF 12-50 Jjumper

2 3

Table 9: Jumper configuration

* Remark to Table 9:From practical point of view it is better to use for the LCF 12-50 feeder cable type:- no jumper cables of type LCF 12-50 J jumper, if no TMA used (instead of 1) and- only 1 jumper cable of type LCF 12-50 J jumper if TMA used (instead of 2), betweenTMA and antenna.The reason is that LCF 12-50 J jumper and LCF 12-50 have the same loss and nearlythe same handling/bending flexibility. Anyway, the LCF 12-50 feeder is usable only forshort distances of 6-7 m, so additional jumpers are difficult to justify.

For the LCF 12-50 J jumper cable of RFS the loss/m is given in Table 10 (withoutconnector losses which must be added; a typical connector loss is <0.02 dB).

LCF 12-50 J jumper 900 MHz 1800 MHz 2200 MHzloss 0.068 dB/m 0.099 dB/m 0.110 dB/m

Table 10: Insertion losses of jumper cable

Typical lengths of the jumper cable LCF 12-50 J jumper are: 1m, 2m or 3m (where2m, 3m are mostly used).

Rule: recommended maximum allowed attenuation (losses of feeder cable+jumpercables+connectors) between the BTS front end connector and the antenna connector is3 dB (value typically used in practice).

Exemplary, Table 11 give the maximum feeder length for the typical losses of RFS’sCellflex cables mentioned in Table 8, considering the jumper configuration of Table 9and the jumper insertion losses of Table 10.Analog, Table 12 gives the maximum feeder length for the case of TMA usage.

Cable type 900 MHz 1800 MHz 2200 MHz

LCF 12-50 44.1 30.3 27.0

LCF 78-50 67 42.0 36.3

LCFS 114-50 93.6 58 50

LCF 158-50 110.8 67.4 57.8

Table 11: Recommended max. feeder length (m) assuming 2x LCF12-50 Jumper usage of 3m each (for 1/2 cable: no jumpers)

Cable type 900 MHz 1800 MHz 2200 MHz

LCF 12-50 35.2 23.2 20.5

LCF 78-50 51.4 29.8 25.0

LCFS 114-50 71.8 41.2 34.4

LCF 158-50 85 47.9 39.8

Table 12: Recommended max. feeder length (m) assuming 3x LCF12-50 Jumper usage of 3m each (for 1/2 cable: 1 jumper)and TX DL insertion loss of TMA (cf. Table 10)

The antenna feeder have to be selected according to the following criteria:

Feeder length dimensioning

Feeder selection

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? maximum allowed feeder length (see Table 11, Table 12)

? site construction constraints (existing space in cable trays and wall breakthroughs,minimum allowed bending radius)

? commercial conditions (price)

Selection rules:

? It is recommended to select the same feeder type for all antennas of a site. Thisminimizes the logistic effort for feeders, mounting kits, clamps, etc. but alsoreduces the risk of installation errors .

? Usually, the usage of the 1/2 “ feeder cable is not recommended; a breakevencalculation shows that the 1/2” cable offers less total loss vs. the 7/8” cable onlyfor very small feeder length of 6-7 m.

? The RNE must first try to use the 7/8” feeder cable due to its lowest price andhighest handling flexibility; it can already cover many practical applications, due tothe achieved length.If the required feeder length is longer than the value indicated in Table 11 for 7/8”the usage of next thickness class is recommended (1 ¼”).If 1 5/8” is still not long enough, the distance BTS-antenna must be reduced or thelosses of >3 dB must be tolerated.One must keep in mind that for e.g. rural tower sites the feeder length must coverthe exemplary distances as indicated in Figure 2.Feeder length:=2m+7m+(H tower-2m-0.5* H ant. radome)+2m ˜ H tower+8m,where 0.5* H ant. radome is approximized with 1 m.

Figure 2: Rural site example; Feeder length + antenna height planning

2.3 Planning TMA usage for GSM

This chapter gives rules for/shows the consequences of TMA usage and illustrates themon an example.For general remarks on TMA see APPENDIX C . Further related documents to this topicare [1.5], [1.6].

? A TMA may be used in coverage driven (noise limited) environments (e.g.suburban/residential, rural, roads).

? If the link budget is UL limited, a TMA usage may be sensible for high power (HP)TRX configurations and for suburban or rural sites with antenna height ≥ 20 m; its

When to use TMA ?

BTS shelter

Lightning protection

7 m 2 m

2 m

Max

. H p

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5H

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jumper

BTS shelter

Lightning protection

7 m 2 m

2 m

Max

. H p

lann

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5H

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2 m

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benefits are the gain in cell range (due to gain in the maximum allowed path loss,MAPL) and the improvement of indoor coverage.

A TMA helps to improve the MAPL in a UL limited linkbudget only if0 < ? - Tx insertion loss of TMA in DL < TMA contribution inULwhere ?=MAPL (DL,no TMA) - MAPL (UL,no TMA)>0and ? - Tx insertion loss of TMA in DL=improvement in linkbudget

The breakeven of TMA usage for the business case is given in [1.6].

For a turnkey project in a coverage driven environment, the improvement inlinkbudget must be at least:• 0.6 dB for area coverage with 3-sectored sites• 0.9 dB for road coverage with 2-sectored sites

? If the link budget is DL limited, a TMA will show no effect on the cell range.

? If the link budget is balanced, the TMA can be used as a network enhancingfeature depending on the operator policy: it efficiently reduces the UL MS poweryielding better MS standby times and reduced UL electromagnetic pollution levels.Also if the link budget is balanced and no power reduction for MS is done, the TMAhelps to increase the UL throughput for GPRS and E-GPRS.

Table 14 and Table 15 indicate for GSM 900 and GSM 1800 in the environmentssuburban, rural, roads: the limiting link in the link budget and if a TMA is sensible orobsolete. The recommendation for TMA usage is based on the:

? computation of typical link budgets for the Alcatel G4 Evolium A9100 BTS for MPand HP (see also [1.4], [1.5], [1.6]);

? BTS output power at antenna connector for the used BTS configurations as given in[7.7]; combining/no combining stands for the operation mode of ANc module inthe BTS;

? TMA parameters for the present products in Table 13.

Band Gain Noise figure TX insertion loss in DLGSM 900 14 dB 1.8 dB 0.6 dBGSM 1800 12 dB 1.8 dB 0.4 dB

Table 13: Most important TMA parameters

GSM 900Medium Power TRX (MP) High Power TRX (HP)

BTS config. withoutTMA

use TMA? BTS config. withoutTMA

use TMA?

3x2 no combining UL rather not (remark1)

3x2 nocombining

UL yes (remark 2)

3x3 combining DL no 3x3 combining DL no3x4 nocombining*

UL yes (remark 2)

3x4 combining DL no 3x4 combining DL no3x6 combining* DL no 3x6 combining* DL noRemarks:* this BTS configurations is realized with 2 cabinets (B7 feature “cell split over 2 BTS”)1. no, if benefit of TMA in MAPL is too low (e.g. 0.4 dB); to be checked case by case2. benefit of TMA in MAPL is typically better than 1.6 dB

Table 14: GSM 900 – Typical link budget limitations and indication for TMA usage

GSM 1800Medium Power TRX (MP) High Power TRX (HP)

BTS config. withoutTMA

use TMA? BTS config. withoutTMA

use TMA?

3x2 nocombining

balance rather not (remark1)

3x2 nocombining

UL yes (remark 2)

3x3 combining DL no 3x3 combining DL no

MAPLUL

MAPLDL

UL no TMA

DL no TMA

TMA

con

trib

utio

n

∆

Tx in

serti

on lo

ss

MAPLUL

MAPLDL

UL no TMA

DL no TMA

TMA

con

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utio

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∆

Tx in

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on lo

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3x4 nocombining*

UL yes (remark 2)

3x4 combining DL no 3x4 combining DL no3x6 combining* DL no 3x6 combining* DL noRemarks:* this BTS configurations is realized with 2 cabinets (B7 feature “cell split over 2 BTS”)1. no, if benefit of TMA in MAPL is too low (e.g. 0.4 dB); to be checked case by case2. benefit of TMA in MAPL is typically better than 2 dB; see example in Table 16

Table 15: GSM 1800 – Typical link budget limitations and indication for TMA usage

Remark to Table 14 and Table 15:

? If the link budget for MP is already UL limited or balanced, the migration from aMP to a HP TRX in the same TRX configuration shows a benefit for the MAPL, only ifthe HP TRX is deployed together with a TMA.

? Improvement (lowering) of the noise figure of the total receive chain =>getting abetter sensitivity (desired) according to Friess formula => increased MAPL.

? Degradation of the blocking and intermodulation characteristics of the BTS (notdesired) i.e. risk to not fully comply with 3 GPP recommendation 05.05 regardingblocking and intermodulation for the case that the value of the TMA amplificationgain (mostly fix cf. TMA data sheet, e.g. 12 dB) greatly exceeds the value of thelosses between the antenna and the input of the base station, i.e. the losses of thefeeder+jumper cables and connectors;This degradation may exist in the G3 and G4 BTS, because the excess gaincompensation capability is =0 for 1-2 TRX (exactly the cases of major interest forthe TMA application in GSM1800) .

Measure to combat BTS blocking characteristics degradation ([1.2]):planning an antenna height = 20 m; realistic for rural, roads and possibly forsuburban sites.

Measure to combat BTS IM characteristics degradation:no measure, since required minimum coupling loss between the antennas of MS andBTS of typ. 100 dB cannot be achieved with realistic BTS antenna heights; however, therisk of having this IM created is extremely low and can be tolerated.If Alcatel suggests TMAs to operators whos gain greatly exceeds the losses offeeder+jumpers+ connectors, these need to be made aware of the possible 3GPP noncompliance of that configuration.

In case TMAs are present in the system, they have to be considered in the networkdesign.

? For the UL path of the link budget in a coverage driven scenario, the TMA impactcannot be treated by simply adding the TMA gain; instead the TMA contributionhas to be added (the TMA contribution is the value indicating the BTS sensitivityimprovement by the TMA). The calculations for the TMA contribution in UL aredone with the Friess Formula (see APPENDIX C ).

? In the DL path of the link budget the TMA will add a Tx insertion loss composed ofthe TMA insertion loss according to the data sheet (Table 13) and the loss of anadditional jumper cable (Table 10).

Given is a 3x2 HP TRX no combining BTS configuration in rural environment withantenna height= 35m. Figure 3 shows the UL receive path for G3 (ANx) or G4 BTS(ANc) in GSM 1800.

Consequences of TMA usage

Impact of TMA on link budget

Example for TMA usage withHP TRX in GSM1800

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Figure 3: UL receive path for G3 (ANx) or G4 BTS (ANc) in GSM 1800

For the calculations the following figures have been considered:

? total cable loss (feeder plus jumpers) of3.0 dB = 2.4+3*0.2 for 40m cable length1.2 dB = 0.6+3*0.2 for 10m cable length

• feeder Cable losses cf. Table 8: 2.4 dB (40m) and 0.6 dB (10m)

• usage of 3 Jumper cable of 2 m each (at point A, between antenna/TMA;point B, between TMA/feeder cable and point C between feeder cable/BTS)Losses per jumper cable=0.2 dB for GSM1800, cf. Table 10.

? Selecom TMA technical data according to datasheet, see Table 13

? for a G3 BTS with a Noise Figure 4dB, a S/N = 6dB leads to a sensitivity of–111dBm, since:sensitivity = -174 dBm + 10*log (200 kHz)+S/N + system noise figure=-121 dBm+ S/N + BTS noise figure= -121+6+4 = -111 dBm

Table 16 gives the exemplary impact of TMA usage for GSM 1800HP TRX. The TMAcontribution (benefit) is calculated with the Friess formula (see APPENDIX C )compared to the same BTS configuration without TMA and the same total cable lossThe new system sensitivity (taking into account the TMA presence) to be considered inthe link budget is calculated in Equation 1:

new system sensitivity= -111 dBm - |TMA contribution|Equation 1: BTS sensitivity calculation due to TMA usage

The benefit of TMA for the MAPL is lower then the TMA contribution since the linkbudget gets DL limited through the TMA introduction.

TMAGain[dB]

Antennaheight [m]

Cablelength[m]

TMAcontribution[dB]

New BTSSensitivity[dBm]

Benefit of TMAfor the MAPL[dB]

Gain incell range[%]

Blocking &IM degradation[dB]

12 35 40 4.2 -115.2 2.1 14 912 35 10 2.6 -113.6 2.1 14 10.8

Table 16: Exemplary impact of TMA usage for GSM 1800 HP TRX

Remark: the blocking degradation (resp. IM degradation) of Table 16 is taken intoaccount for the calculation of the required minimum separation (i.e of the requiredminimum coupling loss) between the antennas of the MS and of the BTS by subtractingthe degradation value from the 3GPP specified maximum allowed in-band blockinglevel for the BTS (resp. from the 3GPP specified maximum allowed IM level caused by2 MS in the receiver front end of the BTS).

Conclusions on the example:

If a TMA with 12 dB gain is applied the benefit for the MAPL is maximum of 2.1 dB.The improved UL sensitivity leads however to a degradation in terms of blocking resp.intermodulation cf. Table 16; but this can be combated resp. tolerated as shown in thesection “Consequences of TMA usage”.

Tower mounted RX

Amplifier (MHA)

Receiver (TRE)

Frontend (ANX or ANC)

BTS

Antenna

A B C D E F Splitter (ANY)

Splitter (ANY)

G H I J

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2.4 Antenna height planning

This chapter gives rules for planning the GSM antenna height, which is key result of theRNP process.

It is quite hard to give a general guideline for antenna height only in function of themorphostructure. Though, the selection of the antenna height, shall be done based on:

? simulations (fieldstrength, coverage, interference probabilities) with a RNP toolsuch as A955, taking into account the morphostructure, the topography, buildinggeometry etc., to meet the QoS requirements in the cell (fieldstrength, coverageprobability);

? necessary clearance in the antenna near field range (cf. Equation 7 , chapter 3.1for flat roof);

? site constraints, due to

• existence of adjacent operator(s) on site;

• maximum mast heights (see below).

The selected antenna height has a strong impact on the cell coverage range andinterference situation in the vicinity. The higher the antenna height, the bigger thecoverage area is, but also the potential interference area.

Especially in the areas where Alcatel doesn’t face any coverage commitment, oneshould try to minimize the antenna height to a value, guaranteeing coverage e.g. forthe intended village, but not covering the tree areas around. Reason: minimize siteconstruction costs (see next subchapter).

For macrocells mounted on masts, two types of masts are used: guided masts (70-80%of cases) and self supporting masts. They are typically offered in the height classesmentioned in Table 17, but the availability of classes may differ on a Alcatel projectbasis.

If possible, the RNE must try to minimize the antenna height to a value fitting into thenext lower mast height class given in Table 17, in order to save installation costs.

The top of the sector antenna radome may reach the top of the tower but neverovertop it due to the lightning protection of the tower.

Guided mast heights [m] 29 35 41 47 53Self supporting mast heights [m] 21 26 31 36 41 46 51

Table 17: Mast height classes [m]

1. Typical µcell antenna heights

Field proven values for µcell antenna height are 3 –15 m and below rooftop, whereasthe umbrella cell antenna height are 15 – 35 m.In cases with very high buildings, µcell antenna height can be > 10m; the big µcell canrelief from traffic congestion in umbrella cell.But the risks associated to high µcell antenna heights are also present if the frequencyspectrum doesn’t allow an optimized frequency plan:-for outdoor MS served by the high µcell, the risk to get the UL disturbed by a neighbour macrosite increases with increasing µcell antenna height-for indoor MS located in higher building floors and served by the high µcell, there is a risk ofDL+UL interference.If the target is to relieve hot spot macrocell from in building traffic, dedicated indoor solutionsmust be evaluated.

2. Impact of close proximity scenario on µcell antenna height

Maximum mast heights

Further issues

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Impact on antenna engineering: choice of µcell antenna height below rooftop, toprevent from receiver blocking of the µBTS receiver (in UL path). However, problemsdue to the close proximity scenario were never reported from the field.

For a description of the close proximity scenario see APPENDIX I .

3. Influence of antenna height on space antenna diversity separation

According to Equation 3 in ch. 2.7.2 the separation of the diversity antennas must be:d_horiz > effective antenna height/10 .

4. Antenna heights in dual band case with single band antennas (solution 2 in chapter2.1)

It is recommended to mount the higher band antennas above the lower band antennasto partially compensate weaker propagation conditions in lower frequency band (e.g.1800 antennas above 900 antennas).

5. Impact of cell split feature on antenna height

If e.g. a 3x8 TRX monoband site is realized with the B7 feature “cell split over 2 BTS’s”(see [7.7]), the same antenna height must be selected for the Tx resp. for the Rxantennas of each BTS rack.

If e.g. a 3x(4+4) TRX multiband cell is realized with the B7 feature “cell split over 2BTS’s” (see [7.7]) by using separate single band antennas (solution 2, see chapter 2.1)the same rule as in the previous point applies.

6. Antenna height planning for hopping networks:

impact on interference situation in networkHopping type

same antenna height regular antenna azimuth tilt tuning Remarks

RFH 1x3 + + + a

RFH 1x1 ++ O ++ a

BBH O O O bTable 18: Impact of height, azimuth, tilt planning for hopping networks

Remarks on Table 18:

? Generally in RFH networks, it is necessary to achieve a minimum coverageoverlap (to reduce interference) which still allows secure HO between cells.

• With a reuse scheme of 1x3: RFH is most efficient if the network design isregulary, i.e same antenna heights, regular antenna azimuths.

• With a reuse scheme of 1x1, the same frequency group is used everywhere;here the requirement to have same antenna height is even higher as for1x3, whereas there is no requirement for same azimuth.

? For BBH networks there are no such constraints on network design.

7. Consideration of antenna height in A955 RNP tool

Reminder for RNE (see Figure 2):

? antenna height used for tool predictions :=height above ground of Tx antenna radome center.

? maximum allowed sector antenna height for the tool predictions:=tower/mast/pole height (without lightning protection) – 0.5* radome size

The top of the sector antenna should never trespass the top of tower/mast/poledue to the existing lightning protection for the construction.Example: for a 31 m mast height, the maximum allowed antenna height for theA955 prediction in GSM 1800 with a typical antenna height of 1.3 m is 30m (infact 30.4m=31m-1.3/2). The antenna connectors at the antenna bottom will be at29.7 m.

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2.5 Planning the antenna azimuth

This chapter gives rules for planning the antenna azimuth, which is key result of theRNP process. First some general rules are given, then some particular cases aretreated.

General rules for azimuth planning:

? For a standard planning, with a standardized 3 sector arrangement, the antennaazimuth is planned following a fixed grid pattern with sector direction e.g. 60°,180°and 300°.

? In urban areas it may not be sensible to direct the main beam of a sector along astraight rectilinear road since this ensures a larger cell range then planned for thismorphoclass. The following scenario is possible: a MS far from the site on the roadmay still be booked on the site due to direct line of sight along the road, whereasthe monitored neighbours in the neighbour list do not offer anymore a sufficientlevel for a secure HO; if the serving cell level further decreases, a call drop ispossible.

? For 2 sector sites on roads in rural area the main beams must follow the directionof the road.

For the co-located dual band TRX’s in GSM900/GSM1800 scenario the planning ofthe antenna azimuth is a critical issue:

? For the co-located single band cells (where solutions 1, 2, 3 of chapter 2.1 arepossible) it is recommended to achieve a maximum coverage overlap in bothbands by planning antenna azimuths identical in both bands.Reason: multiband MS benefit most from the traffic distribution between bands ifthe coverage overlap is maximum; for single band MS’s there is no impact.

? For the multiband cell (where solutions 1, 3 of chapter 2.1 are favoured vs.solution 2) this is even mandatory to do so.Reason: there is no BCCH reception in that regions of the inner zone which do notoverlap with the outer zone.

See subchapter “Further issues” in 2.4.

2.6 Downtilt planning

This chapter gives rules for planning the antenna downtilt in GSM; in UMTS-FDDextensive field experience on the tilt-traffic dependency must be acquired on the field.

General remarks on downtilt for all frequency bands are given in APPENDIX D .

The goal of downtilt planning is:

? for urban areas, to find a tradeoff between maximum fieldstrength level at cellborder and interference reduction;

? for rural areas, to ensure a maximum fieldstrength level at cell border (good fringecoverage).

The downtilt planning is done with a geometrical ray optics method underconsideration of:

? vertical HPBW of the BTS antenna

? BTS and MS antenna height above ground

? effective BTS antenna height (see Figure 6) which takes into account thetopography between BTS and MS location

? morpho-structure in the vicinity of the BTS antenna.

Figure 4, Equation 2, Table 19 show the principle under the simplifying assumption offlat terrain.

Dual band GSM900/GSM1800scenario

Hopping networks

Goal of downtilt planning

Principle

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Figure 4: Assessment of required tilts

There is a strong impact of vertical antenna pattern on the minimum efficient downtiltangle. The downtilt angle is efficient, only if it is bigger than ½ of vertical HPBW (seeFigure 4 and Table 19). For the example of vert. HPBW = 7° a minimum efficientdowntilt angle is 4°.It is possible to further increase the downtilt, e.g. until the vertical pattern’s minimumbetween the main beam and the 1st upper side lobe is oriented towards the horizon.For a vertical HPBW = 7° the first upper side-lobe lies on the horizon line at andowntilt angle of 8°–9°.

Equation 2 gives the rules for calculation of required tilt according to the desiredcoverage range using geometrical ray optics.It gives the dependency of position of points c (corresponding to the upper 3 dB pointin the vertical pattern), b (corresponding to the main beam) and a (corresponding tothe lower 3 dB point in the vertical pattern) of the antenna height above ground (“H”),the required electrical + mechanical downtilt angle (“tilt”) for the main beam and theantennas vertical HPBW (“HPBW”).

)2/tan( HPBWtiltH

c−

= ; )tan( tilt

Hb = ;

)2/tan( HPBWtiltH

a+

=

Equation 2: Tilt assessment with geometrical ray optics

Remark to Equation 2:If e.g. the height ‘H’ is fixed by constraints and the resulting value for ‘tilt’ is relativehigh (>20°) it is worth it to look for alternative lower sites and/or select anotherantenna with a more narrow vertical pattern.Reason: high risk for pattern distortions for the case of flat roof mounting of theantennas.

A calculation example (for qualitative purpose only) is given in Table 19:

Downtilt [°] Dist. of point a [km] Dist. of point b [km] Dist. of point c [km]1 0.38 1.72 over radio horizon2 0.31 0.85 over radio horizon3 0.26 0.58 over radio horizon4 0.23 0.43 3.445 0.20 0.34 1.146 0.18 0.29 0.697 0.16 0.24 0.488 0.15 0.21 0.39

Table 19: Exemplary calculation of points a, b, c positions for antenna height = 30 m, vert. HPBW = 7°, flat terrain

a b

b ca

main beam direction

main beam dir.

HPBW

HPBW

HPBW

2° downtilt7° vertical HPBW

4° downtilt7° vertical HPBWH

tilt

a b

b ca

main beam direction

main beam dir.

HPBW

HPBW

HPBW

2° downtilt7° vertical HPBW2° downtilt7° vertical HPBW

4° downtilt7° vertical HPBW4° downtilt7° vertical HPBWH

tilt

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Figure 5, Table 20 and Table 21 show how the tilt is determined as function ofmorphoclass and coverage range under the simplifying assumption of flat terrain.

With Equation 2 it is possible to adjust cell overlap areas during the initial networkdesign phase, as shown in Figure 5; this first design may be subject for a lateroptimization.

Case 1: tilt planning for dense urban, urban environment

The tilt planning is done for point c in Figure 4, i.e. the upper –3dB lobe of the verticalpattern is directed towards the calculated cell range.It is assumed that multipath propagation ensures for this 3 sectorized cell arrangementa sufficient cell overlap for a secure handover (to be validated on the field).The required tilt can be read out of Table 20 exemplary for a vertical HPBW=7°; herethe cell range may be indoor/incar/outdoor cell range based on coverage and/orcapacity requirements in the cell.

If the required tilt doesn’t match the electrical tilt for the selected antenna in Table 1 anadditional mechanical uptilt/downtilt must be applied.

Further, if this tilt planning leads to HO drop due to

? level (bad coverage) between some distinct sites, less downtilt must be applied,e.g. by using mechanical uptilt;

? interference between some distinct sites, more downtilt must be applied.

Advantages of this tilt planning are:

? frequency reuse improvement through interference reduction further away from site

? improvement of indoor coverage close to the site.

Case 2: tilt planning for suburban, rural, highway environment

The tilt planning is done for point b in Figure 4, i.e. the main beam of the verticalpattern is directed towards the calculated cell range.The required tilt can be read out of Table 21. If the required tilt doesn’t match theelectrical tilt for the selected antenna in Table 1 an additional mechanicaluptilt/downtilt must be applied.For rural areas with big cell ranges, pointing the main beam towards the targeted cellborder, can yield downtilt of ˜ 0°=arc tan (mast height/cell range).

Advantages of this tilt planning: good fringe coverage.

Required tilt

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Figure 5: Tilt planning for different environments

Antenna height [m]cell range [m] 15 20 25 30 35 40 45 50

300 6.4 7.3 8.3 9.2 10.2 11.1 12.0 13.0400 5.6 6.4 7.1 7.8 8.5 9.2 9.9 10.6500 5.2 5.8 6.4 6.9 7.5 8.1 8.6 9.2600 4.9 5.4 5.9 6.4 6.8 7.3 7.8 8.3700 4.7 5.1 5.5 6.0 6.4 6.8 7.2 7.6800 4.6 4.9 5.3 5.6 6.0 6.4 6.7 7.1900 4.5 4.8 5.1 5.4 5.7 6.0 6.4 6.7

1000 4.4 4.6 4.9 5.2 5.5 5.8 6.1 6.41300 4.2 4.4 4.6 4.8 5.0 5.3 5.5 5.71500 4.1 4.3 4.5 4.6 4.8 5.0 5.2 5.41700 4.0 4.2 4.3 4.5 4.7 4.8 5.0 5.22000 3.9 4.1 4.2 4.4 4.5 4.6 4.8 4.9

Table 20: Downtilt (electrical+mechanical) in degrees referring to case 1 of Figure 5 (vertical HPBW=7°)

Antenna height [m]cell range [m] 15 20 25 30 35 40 45 50

300 2.9 3.8 4.8 5.7 6.7 7.6 8.5 9.5400 2.1 2.9 3.6 4.3 5.0 5.7 6.4 7.1

Case 1: Dense urban, urban coverage; Tilt planning for point c (Intersection plane X-X)

X XA B

0.5* R2R2

Cell range R2

Main beam

0.5* R2

Side lob

e

Tilt 2 Tilt 2Site A Site B

Inter Site Distance A-B = 1.5* R2

Case 2: Suburban, rural, highway coverage; Tilt planning for point b

Main beam Main beam

Cell range R1 Cell range R1

Tilt 1 Tilt 1

Inter Site Distance C-D = 2* R1

Site C Site D


X XA B

0.5* R2R2

Cell range R2

Main beam

0.5* R2

Side lob

e




X XA B

0.5* R2R2

X XA B

0.5* R2R2

Cell range R2

Main beam

0.5* R2

Side lob

e




Main beam Main beam


Tilt 1 Tilt 1


Site C Site D


Main beam Main beam


Tilt 1 Tilt 1


Site C Site D

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500 1.7 2.3 2.9 3.4 4.0 4.6 5.1 5.7600 1.4 1.9 2.4 2.9 3.3 3.8 4.3 4.8700 1.2 1.6 2.0 2.5 2.9 3.3 3.7 4.1800 1.1 1.4 1.8 2.1 2.5 2.9 3.2 3.6900 1.0 1.3 1.6 1.9 2.2 2.5 2.9 3.2

1000 0.9 1.1 1.4 1.7 2.0 2.3 2.6 2.91300 0.7 0.9 1.1 1.3 1.5 1.8 2.0 2.21500 0.6 0.8 1.0 1.1 1.3 1.5 1.7 1.91700 0.5 0.7 0.8 1.0 1.2 1.3 1.5 1.72000 0.4 0.6 0.7 0.9 1.0 1.1 1.3 1.4

Table 21: Downtilt (electrical+mechanical) in degrees referring to case 2 of Figure 5

? The tilt angles can be implemented only with a resolution of 0.5°, see also ch. 3.3.

? Prefer electrical vs. mechanical downtilt (refer to APPENDIX D ).

? Tx and all Rx antennas must have the same tilt.

? If e.g. a 3x8 TRX monoband site is realized with the B7 feature “cell split over 2BTS’s” (see [7.7]), the same tilt must be selected for all antennas on each BTS rack.

? For microcell and picocell antenna downtilt is not recommended.Reason: for these very small antennas (i.e. length up to a few tens of cm) with atypical vertical HPBW between 45° and 80°, downtilt is beneficial in terms of fieldstrength reduction only with relative high tilt angles (35° to 50°).

? In a 900/1800 multiband cell scenario (single BCCH, independent whether it isrealized with one BTS or with the B7 feature “cell split over 2 BTS’s”) where the HOalgorithms (e.g. cause 13) assume a constant fieldstrength level difference between900/1800 bands, it is recommended (especially for indoor places with high 1800TRX ratio) to match the fieldstrength level distributions (along the distance) for the900/1800 bands by

• setting different downtilt values for 900 and 1800 bands (typically lower tiltvalue for 1800) or

• possibly selecting single band antennas with different antenna gains andvertical patterns (high RNE effort).

This helps to divert the 900 traffic into the 1800 band with the required QoS andto efficiently use the high number of 1800 TRX’s.A955 RNP tool simulations and sample measurements recorded in the respectiveplaces help to determine the downtilt settings (see [8]).

? In RFH networks, it is necessary to achieve a minimum coverage overlap (toreduce interference) which still allows secure HO between cells.For a reuse scheme of 1x3 and even more for 1x1 a careful tilt tuning isrecommended.

? Combination of mechanical and electrical tilt for GSM :

• Choosing sector antennas with high electrical downtilt (6°...8°) and applyingmechanical uptilt in main beam direction is a very effective means forinterference and range reduction in side lobe direction.The high high electrical downtilt + mechanical uptilt is a favoured solutionvs. low electrical downtilt + additional mechanical downtilt.

• For very high antenna locations (e.g. on the tops of high mountains, or onthe roof-tops of tall buildings for coverage in the street below) a combinationof electrical and mechanical downtilt is recommended.

Further rules on downtilt

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? The antenna manufacturers typically provide two cuts through the radiation patternin horizontal and vertical direction. Mathematically, there is no exact method torebuild a three-dimensional structure from two two-dimensional cuts. Soassumptions and simplifications are made. Different planning tools have differentapproaches, as no exact solution exists. Refer to [9] for A955’s approachdescription (valid for V5 and V6 of A955). Also consider, that A955 does notconsider three-dimensional radiation patterns provided by some antennamanufacturers for parts of their product range.

? If a manufacturer provides for a variable electrical tilt antenna several patterns(e.g. one pattern per tilt value), it is recommended to create as many antenna typesas tilt values, to be able to use all patterns. Reason: within A955 tool, an antennatype can have only one pattern (horiz. and vert.). See also the section “Handling ofcross polar antennas in RNP tools” in ch. 2.7.3.

2.7 Antenna diversity planning

This chapter gives rules for planning antenna diversity in GSM and UMTS-FDD: thiscomprises the Rx diversity, Tx diversity, space diversity and polarization diversity.

General remarks on antenna diversity are given in APPENDIX E and APPENDIX F .

Antenna diversity has only an impact on the service coverage, if the system is ULlimited.

It needs to be checked with a linkbudget for the installed equipment, if there will be animpact on the cell range in UL, see also Table 14, Table 15.If the linkbudget is DL limited by e.g. 2 dB, there will be no improvement in the servicecoverage when improving the UL with better diversity gain.

Table 22 summarizes the GSM rules for diversity planning. For additional details referto the following subchapters.

Environment recommendeddiversity type

Rx Div. gain(UL)

Addit. Tx loss(DL) for cross-polar diversity

Comparison of diversity types for theenvironment

denseurban+urban+ suburban

crosspolardiversity

˜ 3 dB ˜ 0 dB crosspolar diversity:+lower visual impact of antennas+˜ same Rx diversity gain in NLOS areasas with space diversity+air combining possible with ≤ 4 TRX *space diversity:

higher visual impact of antennas- air combining possible only with ≤ 2 TRX*

rural, highway space diversity for horizontalsepar.:˜ 5 dBfor verticalsepar.:˜ 3 dB

1.5 to 3 dB crosspolar diversity:

-negligible Rx diversity gain in NLOS areas

-additional Tx loss of ˜ 1.5 to 3 dBspace diversity:+ high Rx diversity gain in NLOS areas+ no Tx loss+higher visual impact of antennas not asrelevant as in urban environments

*provided, that the requirement is to have max. 2 antennas per sector in dense urban+urban + suburban

Table 22: Summary table with rules and key parameters for GSM diversity planning (+=advantage; –=drawback)

Tilt consideration in RNP tools

Impact on service coverage

Summary

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2.7.1 Rx Diversity gain

Table 23 presents the overview on diversity gains for space and polarization diversity indifferent environments for GSM900/1800. The bold values are for a conservative RNP.The gain for polarization diversity in rural areas has been examined in [2.3].

Diversity gainEnvironment

Space diversity Polarization diversity

same order of magnitudeHoriz separ.: 3..6 dB

dense urban+urban +suburban

Vert. separ: 3..4.5 dB3..6 dB, dep. on ULwave propag. condition(LOS, NLOS, …), MSantenna inclination

Horiz separ.: 5 dBrural, highwayVert. separ: 3 dB

negligible0-0.6 dB

Table 23: Summary on diversity gain for space and polarization diversity in different environments for GSM900/1800

Remarks:

1. The values of Table 23 are valid for maximum ratio combining (MRC) methodused in the Alcatel G3 TRX.For the G4 TRE, and for B6.2 BSS software release onwards, a new combiningmethod (Enhanced diversity combining, see APPENDIX E ) offers additionalantenna diversity gain vs. the MRC method.According to [7.1], currently there are only simulated values available for theantenna diversity gain of the enhanced diversity combining method vs. nocombining (the values are independent on the penetration rate of BTS usingenhanced diversity):

• In interference limited environment (dense urban, urban): 2-5 dBimprovement.

• In noise limited environment (suburban/residential, rural): 3-6 dBimprovement;

As long as the simulated values are not confirmed by extensive field tests, it isrecommended to consider the values of Table 23.

Impact on RNP of enhanced diversity combining:

• No changes on existing antennas and supporting constructions;

• Improved Rxqual in UL direction only;

• The additional gain of the enhanced diversity combining can only beapplied if the mobile and the interfering MS are located in different directionfrom the BTS: this happens typically e.g.a.) in random hopping scenarios orb.) in indoor scenarios where it is desired to reduce the uplink interferingsignals coming from an outdoor micro cell for a mobile in indoorenvironment connected to a G4 TRE.

2. For urban and suburban environment the diversity gain has the same order ofmagnitude.

3. For rural environment polarization diversity gain is negligible (in LOS areas thereare no reflection, diffraction effects which are responsible for polarizationdirection changes).

4. The diversity gain of Table 23 is considered only in the UL path of the linkbudget.

5. Modeling of diversity gain in A955 RNP tool:no impact on predictions, independent if MRC or enhanced diversity combiningmethod is active, since there is no UL prediction in A955; furthermore, the ULpath is further improved through antenna diversity.

Rx Diversity gain GSM900/1800

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In an UMTS system, the RX diversity gain depends on the service, on the multipathprofile and on the velocity. The Rx diversity gain is manifested by a reduction of therequired received uplink Eb/No.

A typical RX diversity gain on Rx Eb/N0 is between 1.5 and 4 dB; it is slightly larger inPedestrian A than in Vehicular A environment since the channel power variations arelarger and the interchip interference is lower in Pedestrian A.

This is shown exemplarily in Table 24 by simulation results for an 8 kbit/s voicechannel simulation results for different services (provided by TD/SYT). The simulationassumption was that the two RX signals were completely uncorrelated, i.e. it can beexpected that in high scatter environments (urban, suburban) the same order ofmagnitude can be achieved with space and cross polar diversity.

Environment Speed Uplink(km/h) 1 antenna 2 antennas Rx Div. Gain3 7.7 5.1 2.66 7.9 5.2 2.710 8.0 5.3 2.725 8.1 5.4 2.750 8.3 5.5 2.8120 8.9 6.3 2.6200 9.5 7.0 2.5

Vehicular A

350 11.1 8.5 2.63 7.2 4.2 3.06 7.7 4.8 2.910 7.8 4.7 3.125 8.2 4.8 3.450 8.6 5.0 3.6

Pedestrian A

120 9.1 5.8 3.3

Table 24: Rx Eb/N0 required for a BER of 10-3 in speech 8 kbps and corresponding Rx diversity gain for UMTS-FDD

2.7.2 Rx space diversity

Required Rx antenna separation for space diversity

There are 2 driving factors for the required Rx antenna separation in case of spacediversity:

? Separation to achieve sufficient signal decorrelation;

? Separation due to effective antenna height.

The recommended and required separation between the two Rx antennas to achievesufficient signal decorrelation and so the space div. gain given in Table 23, Table 24 is:

dH=20λ, dV =15λ

Table 25 gives the corresponding values (λ ≈ 33/16/14.6 cm forGSM900/GSM1800/UMTS-FDD frequency ranges).

frequency bandRx antennaseparation GSM900 GSM1800 UMTS-FDDhorizontal 6.6 m 3.2 m 2.9 m

vertical 5 m 2.4 m 2.2 m

Table 25: Recommended Rx antenna separation for space diversity

Remark: the vertical separation is measured between the antenna radomes (i.e. betweenthe bottom of upper and the top of lower mounted antenna).

Rules:

1. For space diversity prefer horizontal separation vs. vertical separation, due to

Rx Diversity gain UMTS –FDD

Separation to achieve sufficientsignal decorrelation

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• higher diversity gain

• lower mast/pole heights.

On the other hand in case of flat roof mounting of antennas, the number of polespossibly increases (due to 2 poles per sector diversity, but with common usage ofpoles for adjacent sectors) .

2. If the installation space is limited, lower separations than dH=20λ, dV =15λ canbe applied, at the cost of a lower diversity gain, but they should not be reducedbelow 50% of the values in Table 25.There is no deterministic formula to calculate the diversity gain as function ofseparation distance, because the gain is highly dependent on the multipathenvironment.

But a lower diversity gain due to lower separations than dH=20λ, dV =15λ hasonly an effect, if the system is UL limited. It needs to be checked with alinkbudget for the installed equipment, if there will be an impact on the cell rangein UL (see also Table 14, Table 15).

The required (horizontal) antenna spacing is not only determined by Table 25, butadditionally by Equation 3:

d > effective antenna height/10Equation 3: Space diversity separation as function of effective antenna height

where the effective antenna height takes into consideration thetopography as shown in Figure 6.Both conditions need to be fulfilled; the highest separation is valid.

The rule comes into account only for e.g. antennas placed on a 20m tower on a high hill serving the valley below, where the effectiveantenna height can easily trespass 60 m, e.g. 100 m. The dH foroptimum space diversity gain should be 10m, but this is irealistic toimplement. So it is not relevant whether the implemented spacing is6m or less, since the diversity gain given in Table 23 is neverreached and will be low.

Figure 6: Effective antenna height

Dual band resp. triple band cases with Rx space diversity:

? Single band antenna usage: for required Rx antenna separation refer to Table 25.

? Dual band resp. triple band antenna usage: the required Rx antenna separation isdetermined by the lower band requirements in Table 25.

2.7.3 Polarization diversity

The main issues of cross polar antennas application are:

? only Rx application

? Tx+Rx application

? cross polar vs. horiz./vert. polarized antennas

The main issue for the Rx application is the Diversity gain in UL (cf. [2.2], [2.3]):

Separation due to effectiveantenna height

Dual band, triple band

Rx application of cross polarantennas in GSM, UMTS

heff = f ( α,D1, hBTS, hMS)

hMS

D1

MS

BTS

dH

BTS

heff

heff = f ( α,D1, hBTS, hMS)

hMS

D1

MS

BTS

dH

BTS

heff

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? The Rx diversity gain improves only the UL path of the link budget.For achievable values, see Table 23 and Table 24.

? In rural (low scatter) environment, Rx polarization diversity gain is negligible forGSM and UMTS.

The following considerations are valid for GSM and need to be verified for UMTS.

The main issues for the Rx application are the same as above.

The main issues for the Tx application are:

1. Additional pathloss for DL

Pathloss differences between scenarios with cross polarized transmitting antennas andvertical polarized ones depend on propagation conditions (LOS or NLOS, scattering,MS antenna inclination) in the current environment. [2.3] examines the dependency forGSM ( 900,1800).

In high scatter NLOS areas, the polarization of the received wave fronts is independentfrom the polarization of the source antenna and randomly distributed around 360O

(cf. [2.2]). This means, that the polarization of the receiving antenna has no impact onthe pathloss, so that vertical and cross polarized transmitting antennas lead to thesame pathloss result, no matter of which polarization is the receiving antenna.The additional pathloss for the Tx path (DL) in urban/suburban environment for crosspolarized antennas vs. vertical polarized antennas, is ≈0.6 dB, so nearly 0.

In contrary, for a LOS condition, the additional measured pathloss is considerable (upto 4.3 dB) if the polarizations of transmitting and receiving antenna do not match.

Rule of thumb for RNP: for GSM in rural areas, the mean additional loss compared tovertical polarization is in the range of 1.5 to 3 dB.

2. Air combining gain for DL

For air combining principle see APPENDIX F .Air combining is recommended if no heavy visual impact is to fear, as in e.g. ruralareas/highways.

With air combining, combiner losses can be saved, resulting in a lower path loss of ˜ 3dB/saved combiner stage independent on frequency range.To be more accurately on the air combining gain: according to [7.7] the air combininggain isn’t entered anymore directly in the link budget (the former definition of the BTStransmit output power was based on the internal TRE output power e.g. 35 W, fromwhich duplexer, combiner and internal cabling losses were subtracted); instead, thenew definition of the BTS output power specified at the antenna connector alreadyconsiders/omits duplexer, combiner and internal cabling losses.

1. Consideration of the additional pathloss in the A955 RNP tool

For the prediction calculations of A955, only the transmitting aspect is relevant. It isassumed that in this case, the receiving antenna (the MS antenna) is vertical polarized.(However the fact, that in reality a high percentage of receiving MS antennas areinclined is not considered in A955).An additional pathloss is currently not automatically considered in A955 V5/V6, sincethe tool has no information about polarization planes.Workaround: RNE can manually subtract this pathloss from the EIRP for rural regions.

2. Consideration of the air combining gain in the A955 RNP tool

The treatment of the combining gain for A955 RNP tool can be considered by usingthe new specified value of the BTS output power at the antenna connector whichalready omits duplexer, combiner and internal cabling losses.

3. Cross polar antenna pattern modeling in RNP tools

Tx+Rx application of cross polarantennas in GSM

Handling of cross polarantennas in RNP tools

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Some antenna manufacturers provide antenna patterns for different spectrum portionsin the same band (e.g. for UL/DL) and for different polarizations (+45° / – 45°; theyresult from co-polar measurements, i.e. Tx and measuring Rx antenna have the samepolarization). In the main beam direction the patterns are typically very similar, but inthe side lobes differences of = 20 dB are possible. Since RNP tools generally (andA955 particularly) cannot handle more than one (horiz. and vert.) antenna pattern, thedifferent pattern data has to be preprocessed by the planner.A955 V5/V6 currently:

? has no information about polarization planes;

? can consider only one of the antenna diagrams, i.e it assumes the same relativeantenna gain and though predicts the same pathloss for the DL and UL spectrumportions of the same frequency band.

Example: a broadband crosspolar antenna for GSM 1800/UMTS with variableelectrical downtilt (0°-8°) has 20 patterns specified by the manufacturer: for each of the5 downtilt values (0°, 2°, 4°, 6°, 8°), 4 antenna patterns are given (for UL band in +45°polarization plane , UL –45°, DL +45°, DL –45°). Preprocessing yields one antennapattern for each considered downtilt value and it typically involves the following steps:

? conversion of the dB pattern values into W

? averaging the W values for UL+45°, UL –45°, DL +45°, DL –45°

? conversion of W values back into dB.

Cross polar antennas have the same polarization diversity gain compared tohoriz./vert. polarized antennas. Still, cross polar antennas are preferred instead ofhoriz./vert. polarized antennas because: in case of air combining, both polarizationdirections of a cross polar antenna can be used for Tx, whereas only the verticalpolarization direction of a horiz./vert. polarized antenna can be used for Tx ([2.3]shows that important losses can also be expected on the horizontal polarizationdirection, assuming a vertical polarized MS antenna).Air combining with horiz./vert. polarized antennas is not practicable; so, horiz./vert.polarized antennas have a low market penetration.In this document, the focus within dual polarized antenna class will be only on crosspolar antennas and not on horiz./vert. polarized antennas.

2.7.4 GSM space and polarization diversity on UL

An interesting combination of space and polarization diversity is given in Figure 7.

Figure 7: GSM 4-RX diversity on UL

It is not a 4-Rx diversity, since for a given call only 2 reception paths are present. Forthe separation D, Table 25 applies. The gain benefit of this mixed diversityconfiguration is expected to be higher than the one indicated in Table 22 (to beconfirmed on field tests.

2.7.5 Further rules on diversity

For the Rx application the selection between space and polarization diversity is basedon the diversity gain, according to ch. 2.7.1:

Cross polar vs. horiz./vert.polarized antennas

Selection space vs. polarizationdiversity for GSM900/1800

TRX1 TRX2 TRX3 TRX4

Ant. A Ant. B

ANC 1 ANC 2

D

TRX1 TRX2 TRX3 TRX4

Ant. A Ant. B

ANC 1 ANC 2

D

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? For dense urban, urban and suburban areas crosspolar antennas arerecommended.

? For rural areas and highway coverage in a tyypical coverage driven planning, thespace diversity (with vertical polarized antennas) is recommended.For the exceptional case of a traffic driven planning in these environments,crosspolar antennas can be considered to minimize project logistic.

Cross polar antennas must be used in urban and suburban areas, whereas twoseparated vertical polarized antennas must be used in rural areas for space diversity.

Space and cross polar diversity are compatible with mechanical and electrical downtilt;but in general electrical downtilt is preferred vs. mechanical downtilt (see ch. 2.6),especially in UMTS (interference limited system).

The orientation of the Rx diversity antenna arrangement must correspond to the cellorientation (see Figure 8), to achieve highest space diversity gains (cf. [10])

Figure 8: Orientation of Rx antennas for space diversity

2.7.6 UMTS-FDD Tx diversity

In this chapter only the expected gain due to STTD and closed loop mode 1 is given.Further details on UMTS-FDD Tx diversity are provided in APPENDIX E and [6.1].Simulation results on Tx diversity gain for different services are provided by TD/SYT in[6.2].

The Tx diversity gain provided by Tx diversity in DL is manifested by 2 effects:

? a reduction of the required Tx DL Eb/N0.

? a reduction of the required Rx DL Eb/N0 .

For Tx Eb/N0 and Rx Eb/N0, the denominator N0 denotes the noise measured at thereceiver side and Eb is the energy per information bit at the transmitter side andreceiver side respectively.

Table 26 exemplary shows Tx DL Eb/N0 required for a target BLER=10-2 (AMR 12.2kbps) and the corresponding Tx diversity gain for STTD/ Closed loop mode 1 for the3GPP defined multipath environments Vehicular A (representative for macrocellularpropagation) and Pedestrian A (microcellular propagation). Some remarks on theTD/SYT simulation results:

? STTD always improves the performance compared to no transmit diversity. Thelargest gain is obtained for low speed and environment with low multi-pathdiversity such as rural or indoor environments (3.3 dB in Pedestrian A environmentat 3 km/h). The gain then rapidly decreases when the speed increases.

? Closed loop mode 1 improves the performance compared to no transmit diversityonly for low mobile speeds (typically below 60-80 km/h) and degrades themotherwise. The largest gain is obtained for low speed and environment with lowmulti-path diversity like with STTD (4 dB in Pedestrian A environment at 3 km/h).

? Comparison STTD/Closed loop mode 1: the closed-loop mode 1 enables betterperformance (higher capacity gain) than STTD for low mobile speeds (below 50-60km/h). For larger mobile speeds (above 50-60 km/h), STTD enables betterperformance.

? A big advantage of STTD over closed-loop mode 1 is that STTD is always betterthan no transmit diversity, which is not the case of closed-loop mode 1. Indeed,closed-loop mode 1 degrades the performance compared to no transmit diversity

Selection space vs. polarizationdiversity for UMTS-FDD

Compatibility of downtilt anddiversity

Rx antenna orientation in spacediversity

Tx diversity gain

RxA

RxB

MaximumDiversity

RxA RxB

MaximumDiversity

CellBorderCorrect orientation Incorrect orientation

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for medium and large mobile speeds (above 60-80 km/h) with a loss that may besignificant (up to 1.1 dB at 120 km/h and even larger loss above 120 km/h).

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DL Target transmit Eb/N0 Tx diversity gain

Environment Speed(km/h)

WithoutTx

diversity

STTD Closed-loop

mode 1

STTD Closed-loop

mode 13 7.4 6.7 6.2 0.7 1.2

6 7.7 6.8 6.3 0.9 1.410 7.4 6.7 6.3 0.7 1.125 7.0 6.6 6.1 0.4 0.950 6.6 6.3 6.4 0.3 0.2

120 6.8 6.6 7.9 0.2 -1.1250 8.1 8.1 9.6 0 -1.5

Vehicular A

350 10.1 10.1 14.3 0 -4.03 11.3 8.0 7.3 3.3 4.06 11.1 8.0 7.3 3.1 3.8

10 10.8 8.3 7.2 2.5 3.625 8.9 7.2 6.8 1.7 2.150 8.0 7.1 6.5 0.9 1.580 7.9 7.0 7.8 0.9 0.1

Pedestrian A

120 7.9 7.0 8.6 0.9 -0.7

Table 26: Target Tx DL Eb/N0 and corresponding Tx diversity gain for UMTS-FDD for a target BLER = 10-2 (AMR 12.2 kbps)

Table 28 shows Rx DL Eb/N0 required for a BER of 10-3 in speech 8 kbps and thecorresponding Tx diversity gain for STTD in the multipath environments Vehicular Aand Pedestrian A (simulation results provided by TD/SYT):

? Only a slight reduction is achieved (= 1 dB).

? The Tx diversity gain on Rx Eb/N0 is larger for Pedestrian A than for Vehicular A.

Downlink

Environment Speed[km/h]

Eb/Nowithout Txdiversity[dB]

Eb/NoSTTD[dB]

Tx div. gain [dB]

3 6.8 6.6 0.2

6 7.1 6.9 0.210 7.2 7.0 0.225 7.2 6.9 0.350 7.4 7.1 0.3120 7.6 7.5 0.1200 8.4 8.2 0.2

Vehicular A

350 10.4 10.0 0.43 6.5 6.3 0.26 7.1 6.6 0.510 7.6 6.9 0.725 8 7.0 150 8.3 7.3 1

Pedestrian A

120 8.5 7.7 0.8Table 27: Rx DL Eb/N0 required for a BER of 10-3 in speech 8 kbps and corresponding Tx diversity gain for UMTS-FDD

1. For Tx diversity the 2 Tx paths need to be uncorrelated; this is achieved by:

• space diversity: for the separation rules refer to chapter 2.7.2 and Table 25;

• polarization diversity.

Impact on antenna engineering

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2. With duplexer usage, each Rx diversity antenna can also be used for transmissionwith Tx diversity.

3. TX diversity gain variation in urban and rural environment: to be studied on field.

4. Consideration of TX diversity gain in A955 RNP prediction: use Eb/No of Table 26.

2.7.7 UMTS FDD 4-RX diversity on UL

The gain of 4-RxDiv can be mapped onto a gain in cell range only in case of limitedUL in the link budget. If the system is DL limited, 4RxDiv will show no effect on the cellrange (cf. [6.3]).The diversity gain is manifested by a reduction of the required Rx UL Eb/No which willimprove the coverage and capacity performance of the system.

The potential gain of receive antenna diversity with 2, 3 or 4 perfectly uncorrelatedantennas is simulated by TD/SYT for vehicular A and pedestrian A environments,where the BER is measured at the output of the channel decoder ([6.3]). For a BER of10-3 there is a difference on Rx Eb/No level in the node B of:

? ˜ 3 dB between using 1 or 2 receiving antennas;

? ˜ 2 dB dB between using 2 or 4 receiving antennas.

The real potential gain of 4-RxDiv will depend on the environment (propagationchannel), the service (BER or BLER), the speed of the mobile and antennacharacteristics.

4-Rx diversity for UMTS-FDD is provided optionally only in the Node B.

To achieve these gains the decorrelation of the Rx branches must be ensured by spacediversity or polarization diversity.

? For space diversity, this decorrelation can be achieved by spatially separating theantennas, horizontally or vertically, by applying the separation rules of Table 25and Equation 3.

? For polarization diversity, the decorrelation is obtained with cross polar antennas(+/-45°).

The upgrade strategy towards 4Rxdiv depends on the previously implemented 2Rxdivantenna solution.

Upgrade starting from space diversity

? Initial situation: 2RX diversity scheme with single polarized antennas and vertical orhorizontal separation.

? After upgrade: for low visual impact, replacement of the 2 existing antennas with 2cross polar antennas, see Figure 9.

Figure 9: 4-Rx div upgrade starting from space diversity

Upgrade starting from polarization diversity

? Initial situation: 2RX diversity scheme with 1 cross polar antenna (typical in denseurban, urban, suburban environment).

Diversity gain

Implementation

Upgrade towards 4Rxdiv

Distance d

Rxdiv1 Rxdiv2

SpaceDiversity

Verticalpolarisedantenna 2

Verticalpolarised

antenna 1

Distance d

Rxdiv1 Rxdiv2 Rxdiv3 Rxdiv4

SpaceDiversity

PolarisationDiversity


Xpolantenna 2

Xpolantenna 1

Replace Antennas

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? After upgrade: combination of space and polarization diversity; adding of anadditional cross polarized antenna, either vertically or horizontally separated fromthe first one; the separation rules of Table 25 and Equation 3 must be respected;higher visual impact; see Figure 10.

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Figure 10: 4-Rx div upgrade starting from polarization diversity

2.8 Intra-system and inter-system compatibility assessment for site sharing

Mobile intra-system and inter-system compatibility for the same site have an impact onantenna engineering of this site. This chapter describes the methodology forcompatibility analysis and shows how to achieve the compatibility. For relateddocumentation to this topic see [5.1].

The possible interference scenarios and most important EMC interference mechanisms(Transmitter Noise/Spurious Emissions , Blocking, Intermodulation) need to becombated to guarantee the intra-system and inter-system compatibility for sitesharing/co-location. They are described in APPENDIX H .

The assessment methodology for mobile intra-system and inter-system compatibility forsite sharing (co-siting) consists in the following steps (for GSM and UMTS):

1. Listing of possible relevant intra- and inter-system incompatibility issues.example: for a site which is shared by operator1 (which operates in 900/1800dual band) and operator2 (which operates UMTS) the possible systemincompatibility issues are: a.) intra-system incompatibility inside 900, 1800, UMTSb.) inter-system incompatibility between 900-UMTS, 1800-UMTS, 900-1800.

2. For the cases identified in step 1:

• Analysis of the 3 EMC interference mechanisms by considering:

• the requirements specified by the relevant standardization body (e.g.3GPP for GSM and UMTS) for: level of spurious emissions, level ofblocking limit, in-band IM attenuation etc.

• the Alcatel values for: level of allowed spurious emissions, level oflimiting interference signal (for spurious emissions), level of allowedblocking limit, allowed IM level etc.(In order to prevent performance degradation for co-located mobilesystems, the BTS hardware of the vendor needs to fulfill therequirements specified by the relevant standardization body.)

• Determination of the resulting decoupling requirements for each of the 3EMC interference mechanisms.

• Finding out which decoupling values are the dimensioning ones (see Table28, Table 29 for some important combinations).

3. Planning how to implement the decoupling.

For exemplary calculations see [5.1].

Definition: The decoupling (isolation) is measured between the antenna connectors ofthe transmitter in mobile system 1 and of the receiver in mobile system 2, as shown inFigure 11. The achievable decoupling value is strongly influenced by:

EMC aspects

Methodology

Tx/Rx decoupling requirements

Rxdiv3 Rxdiv4


Xpolantenna

Distance d

Rxdiv1 Rxdiv2 Rxdiv3 Rxdiv4

SpaceDiversity



Xpolantenna 2

Xpolantenna 1

add Xpol antenna in distance d

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? the antenna spacing between Tx antenna (of mobile system 1) and Rx antenna (ofmobile system 2),

? the gains and radiation patterns of the 2 antennas,

? the presence of filters and diplexers.

Figure 11: Definition of required decoupling

Alcatel proposes in Table 28 (cf. [5.1]) the Tx/Rx decoupling requirements for intra-band and some important inter-band mobile system co-locations, both for Alcatel BTSand other vendors BTS (also fulfilling the mentioned 3GPP specifications); Table 28also mentions the interference mechanism which is the dimensioning one.

GSM900 (RX) GSM1800 (RX) UMTS (RX)

Specificationaccording to:

GSM05.05

Alcatel GSM05.05

Alcatel 3G TS25.104

Alcatel

GSM 05.05 25 dB

IM

46 dBBlocking

25 dBIM

v.8.5.1:34dBGSM

spurious

GSM900 (TX) →

Alcatel 25 dB

IM

46 dBBlocking

25 dBIM

v.8.5.1:34dBGSM

spurious

61 dB

Blocking

30 dBBlocking

GSM 05.05 39 dBBlocking

25 dBIM

25 dBIM

v.8.4.1:85 dB

v8.5.1:34dBGSM

spurious

GSM1800 (TX) →

Alcatel 39 dBBlocking

25 dBIM

25 dBIM

v.8.4.1:85 dB

v8.5.1:34dBGSM

spurious

62 dB

Blocking

34 dBGSM

spurious

3G TS 25.104 35 dBBlocking

30 dBBlocking

43 dBBlocking

30 dBBlocking

58 dBBlocking

34 dBSpurious

UMTS (TX) →Alcatel 35 dB

Blocking30 dBBlocking

43 dBBlocking

30 dBBlocking

58 dBBlocking

34 dBSpurious

Table 28: Tx/Rx decoupling requirements for some important system co-locations

Remark:

the requirements specified by 3GPP are based on the assumption that the decoupling(between the Tx antenna connector of mobile system 1 and the Rx antenna connectorof mobile system 2, as shown in Figure 11) provided by the antenna system isminimum 30 dB; this assumption is indeed confirmed by antenna manufacturermeasurement series, refer to [RFS 1]. But by using the Alcatel EVOLIUM™ 9100 BTS(G3, G3.5, G3.8, G4, G4.2, Evolution step 1, Evolution step 2), even less decouplingis required than the 30 dB of Table 28:

? For certain combinations 900 TX-900 RX, 1800 TX-1800 RX, 900 TX-1800 RX,1800 TX-900 RX: 25 dB are sufficient (IM is the dimensioning scenario; TransmitterNoise/Spurious Emissions: no problem, due to high selectivity of Tx filter asspecified by 3GPP for GSM; Out-of-band blocking: no problem, due to the highselectivity of the Rx filters).

? For other combinations, the 30 dB in Table 28 provide additional safety margin,since the required decoupling is also less than 30dB due to relaxed receiverblocking requirement (derived from [5.1]), see Table 29.

BTSorNode B

TX power

AntennaAntenna

BTSorNode B

Decoupling

TxRxBTSorNode B

TX power

AntennaAntenna

BTSorNode B

Decoupling

TxRx

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required decoupling900 Tx-UMTS Rx 21 dBUMTS Tx-900 Rx 18 dBUMTS Tx-UMTS Rx 13 dB

Table 29: Tx/Rx decoupling requirements for Alcatel BTS co-location in some important systems

2.8.1 How to ensure the intra-system and inter-system compatibility?

This chapter gives engineering hints on how to achieve the sufficient decoupling forintra-system and inter-system compatibility.The decoupling to combat the 3 interference mechanisms is achieved by spaceseparation, filters, diplexers and duplexers.Additionally for IM a careful frequency planning is required.

Space separation

For the intra-system case it is possible to apply the empirical formulas below (source:Celwave/RFS) giving an orientative value for the decoupling; they are applicable:

? for calculation of the decoupling/isolation between Tx/Rx antennas of

• the same sector;

• adjacent sectors;

• co-sited adjacent operators;

? for in-band case in GSM and UMTS bands;

? for omni and directional antennas;

? for vertical polarized Tx/Rx antennas ;

? for 0° mechanical tilt.

The distance required for a specific isolation varies with operational frequency andantenna gain. Lower frequencies and higher gains require greater separations.

1. Achievable decoupling/isolation DV by vertical separation

DV=28+40log(dV/λ) [dB]Equation 4: Decoupling by vertical separation

dV = vertical separation as indicated in the sketch

λ = wavelength (GSM900 ≈ 33 cm, GSM1800 ≈ 16 cm; UMTS-FSS ≈ 14.6 cm)

This formula is only valid for dV/λ > 10

For optimum distance dm to the mast/wall, see ch. 3.1.

2.) Achievable decoupling/isolation DH by horizontal separation

DH=22+20log(dH/λ)-(GT(ϕ)+GR(ϕ)) [dB]Equation 5: Decoupling by horizontal separation

This formula is only valid for dH/λ > 10

GT and GR are gains (T=transmit; R=receive) measured on the horizontal antennadiagrams of the Tx and Rx antennas in the direction (angle ϕ) of the imaginary“antenna connection line”, i.e. = (gain in main beam direction – relative gain indirection ϕ)

3.) Achievable decoupling D by combination of horizontal and vertical separation

D=(DV-DH)α/90°+DH [dB] (no tilt considered )Equation 6: Decoupling by of horizontal+vertical separation separation

dv

dm

Mast

Tx

Rx

dv

dm

Mast

Tx

Rx

dHTx RxdHTx Rx

dH

dV

αTx

RxdH

dV

αTx

Rx

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This is a linear interpolation of the 2 formulas above.

Remarks to the decoupling Equation 4, Equation 5, Equation 6:

1. Since the formulas given are not exact and have several restrictions, it isrecommended to carry out decoupling measurements locally on the site to verify thecompliance with the requirements. This is the more recommended in the cases:

• the separation distances yielded by the mentioned formulas, are too highand not feasible for the network operator (from financial, visual, civilengineering/site construction etc. p.o.v.);

• mechanical downtilt application;

• cross polar Tx/Rx antenna usage;

• inter-system co-siting with substantially different frequency band (e.g.GSM1800-UMTS).

2. In case of spatial Tx/Rx separation with dual band / triple band antennas, thedecoupling values of the lowest frequency band are dimensioning.E.g. for GSM900/1800, the isolation has to be calculated for the 900MHz band,since the decoupling for horizontal separation is 6 dB lower than in 1800MHz andfor vertical separation 12 dB lower than in 1800MHz (Figure 12).

Figure 12 shows the achievable decoupling based on horizontal (for a 11dBi omniantenna) and vertical separation according to equation given above.

Figure 12:Decoupling achieved by horizontal and vertical separation

In Figure 13, the antenna separation dH and dV between Ant A and Ant B isdH and dV := max { X, Y} where

X=space diversity separation cf. Table 24 between RxA-RxdivA, RxB-RxdivB

Y=decoupling separation cf. Equation 4, Equation 5, Equation 6 between TxA-RxB,TxA-RxdivA, TxB-RxA, TxB-RxdivB.

Figure 13: Antenna spacing for the Evolium A9100 BTS (G3 /G4) with antenna diversity

Antenna spacing for the EvoliumA9100 BTS (G3 /G4) with

antenna diversity

ANC

ANC

TxA, RxA, RxdivB

TxB, RxB, RxdivA

TxA, RxA, RxdivB

TxB, RxB, RxdivA

Evolium BTS

dH

dV

Ant A Ant B

Ant A

Ant BANC

ANC

TxA, RxA, RxdivB

TxB, RxB, RxdivA

TxA, RxA, RxdivB

TxB, RxB, RxdivA

Evolium BTS

dH

dV

Ant A Ant B

Ant A

Ant B

15

20

25

30

35

40

1 2 3 4 5 6 7 8 9 10

Horizontal separation (m)

Deco

up

lin

g D

h (

dB

)

GSM 900GSM 1800

60

65

70

75

80

85

90

95

100

105

110

1 2 3 4 5 6 7 8 9 10

vertical separation [m]

Deco

uplin

g D

v [d

B]

GSM 900

GSM 1800

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Rule:

For the Evolium A9100 BTS (G3 /G4) with antenna diversity, the decouplingrequirement is easier fulfilled with a vertical separation of antennas (horizontal spacingdistances may not be feasible in practice). This is valid for omni and directionalantennas, and for any frequency range.But this must be balanced against the fact that the diversity gain for vertical separationis ˜ 2 dB lower than for horizontal separation (see Table 22, Table 23).

Example 1: Low-loss configuration for more then 2 TRXs per sector

Figure 14: Separation for low-loss configuration for more then 2 TRXs per sector

Given is a low-loss configuration Evolium A9100 BTS (G4) with 4 TRX’s/sector (e.g. forrural areas in GSM1800) and directional vertical polarized antennas of Celwave seriesAP 186516 (65° horiz. HPBW, 7.5° vert. HPBW, 17 dBi gain) see Figure 14.

The issues are:

? Tx/Rx antenna spacing inside the same sector: D1, D2=?

? Tx/Rx antenna spacing between adjacent sectors (of the same operator) D3 =?

D1 (between the antennas of the same ANc, i.e. A-B and C-D)

The distance D1 is determined by the diversity spacing requirement of Table 25.Here it is recommended to choose horizontal separation (if site installation space is notlimited) to achieve higher diversity gain (see Table 23). With vertical separation siteconstruction is simplified however the required separations can also lead to hightowers.

D2 (between the antennas of the 2 ANc’ s of the same sector, i.e. A-C, A-D, B-C, B-D)

Two solutions are possible as indicated. The distance D2 is determined by theminimum decoupling requirement of the Evolium BTS to prevent from IM which is min.25 dB between TX and RX paths (Table 28).

The formulas in 2.8.1 can be used only for calculation of the theoretical decoupling ford/λ>10, yield: D2 (solution 2) << D2 (solution 1) and are not practicable.

Examples for space separation

TRX1 TRX2 TRX3 TRX4

Ant. A Ant. B Ant. C Ant. D

ANC 1 ANC 2

D1 D2 D1

Ant. A Ant. B

Ant. C Ant. D

ANC 1 ANC 2

D1

D1

TRX2 TRX3 TRX4TRX1

D2

solution 1 solution 2

TRX1 TRX2 TRX3 TRX4

Ant. A Ant. B Ant. C Ant. D

ANC 1 ANC 2

D1 D2 D1

Ant. A Ant. B

Ant. C Ant. D

ANC 1 ANC 2

D1

D1

TRX2 TRX3 TRX4TRX1

D2

solution 1 solution 2

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Practically, decoupling measurements done locally on the site by RFS/Celwave (cf. [RFS1]), typically yield for GSM1800 antennas of series AP 186516 a minimum isolation of:

? 30 dB, at 0 cm horiz. antenna separation (i.e. A+C, B+D may almost touch)

? 60 dB, at 0 cm vertical separationSeen from this p.o.v., solutions 1 and 2 are equally recommended.

D3 (between the antennas of the two ANc’ s of adjacent sectors)

The distance D3 must respect the same requirement as D2. So, for the typical case of a3 sector site with equal 120° sector arrangement (i.e. sites, where the antennas of thesectors point in different directions and installation space on the site is sufficient toavoid crossing of antenna main beams) the antennas of the adjacent sectors mayalmost touch each other (decoupling measurements cf. [RFS 1] typically yield aminimum isolation of 30 dB at 0 cm horiz. antenna separation).

Example 2: similar to example 1, but antennas A+B, C+D are each replaced by oneGSM1800 cross polar antenna of Celwave series APX 186515 (65° horiz. HPBW, 7 °vert. HPBW, 17.5 dBi gain). (Remark: lets consider this although it is better to usespace diversity in rural areas)

D1 – not applicable in this case

D2 – similar considerations as in example 1

? For calculation of the theoretical decoupling, the formulas in 2.8.1 are notapplicable.

? Practically, decoupling measurements cf. [RFS 1] yield for cross polar antenna ofthe type APX 186515 (65° horiz. HPBW, 7 ° vert. HPBW, 17.5 dBi gain) and APX186516 (65° horiz. HPBW, 4.5 ° vert. HPBW, 18.3 dBi gain) a minimum isolation of

• 45 dB (worst case for co-polar or cross-polar measurement), at 0 cmhorizontal antenna separation

• 55 dB (worst case for co-polar or cross-polar measurement), at 20 cmvertical antenna separation

Seen from this p.o.v., solutions 1 and 2 are equally recommended.

D3 – similar considerations as in example 1

Decoupling measurements for type APX 186515 (resp. APX 186516) cf. [RFS 1],typically yield a minimum isolation of 30 dB at 0 cm horiz. antenna separation (worstcase for co-polar or cross-polar measurement)

Example 3: similar to example 1, but for GSM900

same conclusions as in example 1.

Example 4: similar to example 1, but for dualband sites GSM900/GSM1800

Given is a dualband Evolium A9100 BTS (G4) configuration with 2 TRX’s/GSM900 + 2TRX’s/GSM1800.

For each frequency band the chosen antennas are directional, single band, verticalpolarized antennas (let’s assume that the operator preferred single band antennas forflexible tilt tuning and antenna space diversity for rural area)

? for GSM 900 Celwave AP 909014 (90° horiz. HPBW, 8.5° vert. HPBW, 16 dBi)

? for GSM 1800 Celwave AP 189014 (90° horiz. HPBW, 7.5° vert. HPBW, 16.1 dBi)

Same considerations apply as in example 1.

D1- will be different for GSM900 and GSM1800

D2- decoupling measurements for vertical polarized antennas will typically yield aminimum isolation of

? 30 dB (in GSM900) and 32 dB (in GSM1800), at 0 cm horizontal antennaseparation

? 40 dB (in GSM900) and 52 dB (in GSM1800), at 0 cm vertical separation

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D3- Same considerations as in example 2.

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2.9 EMC impact on antenna system planning

When a site needs some re-engineering to respect the exposure index in a neighbourliving place (mainly fixed by local authorities), the most straightforward solution is tochange the height, the tilt or the EIRP. These modifications will then impact thecoverage and frequency reuse in neighbour cells.

This chapter anticipates how Alcatel would implement these changes and what wouldbe the actual impact on dense urban and urban environments. Reason: the exposureindex requirement has not been finally settled for the time being.

Option 1: if site re-engineering is not desired/allowed/possible, the certain distancesmust be respected to fulfil the exposure index requirement.

Option 2: site re-engineering by increasing only the antenna height

Advantage: the coverage gets better (this may not necessarily be an advantage if thecoverage was sufficient before the modification)

Drawbacks:

? risk to increase the interference (if no additional downtilt can be applied)

? limitation on antenna mast height may apply

? critical/not feasible in case of mast sharing with competitor operator

Option 3: site re-engineering by decreasing only the antenna downtilt

Drawbacks:

? close to the site, it is almost impossible to reduce the exposure index to therequired limit even with 0° downtilt

? far from the site, the interference risk is increased (especially in 1x1 RFH networks)

Option 4: site re-engineering by reducing only the EIRP of the BTS

Consequences:

? undermining the benefit of high power TRX in MAPL

? less coverage and increased number of sites

Option 5 (most probable): site re-engineering by mixed solution, i.e antenna heightincrease + downtilt increase + EIRP reduction

2.10 RNP tool related aspects on antenna planning

This chapter summarizes the handling of the antenna system planning aspects whichare relevant from point of view of RNP tool (e.g. A955) handling. These are:

? filling of the vertical antenna pattern outside the main beam;necessary in order to approach the prediction to the measurements; currently thistopic is under investigation in PCS

? planning for a maximum antenna height, see chapter 2.4 ;

? consideration of vertical patterns with an electrical tilt, see chapter 2.6;

? handling of crosspolar antenna patterns, see chapter 2.7;

? respecting the exposure limit in a specified distance from the antenna to the nextbuilding/housing apartment in main beam direction, see chapter 2.9

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3 RULES FOR ANTENNA INSTALLATION

Some issues arising during antenna installation are not subject of the network designphase. This chapter gives rules for antenna mounting during installation phase.

3.1 Mounting rules for tower, mast, roof, wall mounting of antennas

This chapter gives mounting rules for omni, sector, macro and micro antennas forcommon mounting places; this comprises mainly clearance rules such as:

? minimum mount distance of omni antennas from supporting structure, see 3.1.1

? minimum mounting height of antennas (see 3.1.2)

? maximum skewing angle for antennas relative to a reflective surface (see 3.1.3).

The considerations below are generally valid for GSM and UMTS. Further details arecontained in APPENDIX G .

Table 30 gives a summary on the required standard mounting restrictions.

If the rules cannot be respected, site operation is still possible but with QoS resultsworse as predicted.

Mounting on Omni Sector (remark 2)Tower top NR, remark 1 n.a.

side see 3.1.1 see 3.1.3Mast top NR, remark 1 n.a.

side see 3.1.1 NRRoof top wall (e.g. elevator shaft) n.a. see 3.1.2,3.1.3

mast - top see 3.1.2 n.a.

Macroantennas

mast - side see 3.1.1, 3.1.2 see 3.1.2µ antennas Wall see 3.1.4 see 3.1.4

Table 30: Summary on required mounting restrictions (NR=no restriction; n.a.= not applicable)

Remarks to Table 30:

1. For top mounting of omni antennas on tower /mast (nowadays rarely done) : nomounting restrictions apply if there are no further obstacles in the near field range,except the lightning protection. An almost circular pattern is created (with sometolerable ripples in the pattern due to the lightning rod).

2. For side mounting of sector antennas on a tower/mast/wall, the mounting spacingto the tower/mast/wall can be reduced to a feasible minimum (i.e. ˜ 0 cm), sincethe antenna housing acts as an reflector (everything “behind” the antenna has noimpact on the pattern).

3.1.1 Side mounting of omni macro antennas on mast/ tower

A tower or mast, which usually consists of a good reflecting material (steel, concrete),changes the antenna pattern considerably. Decisive factors are the spacing betweenthe mast and the antenna as well as the mast dimensions.

For side mounting of omni antennas on a cylindrical mast the antenna manufacturercan calculate the resulting pattern relatively simply for typical radiation patterns.

An exact quantitative degradation calculation can be simulated by the antennamanufacturer.

Figure 18 in APPENDIX G shows the degradation of the pattern independent fromthe frequency range [KAT 1]. It can though be used for RNP purposes, only from aqualitative p.o.v., since e.g. a mast diameter of 0.04 lambda is not feasible. But onecan see, that a spacing of 0.25 λ, 0.50 λ, 0.75 λ may be implemented to achieve thedesired coverage around the site.

Cylindrical mast

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For side mounting of omni antennas on a lattice tower the antenna manufacturer cancalculate the resulting pattern, but the modeling of each tower element causingreflections (tower legs, bracing, existing ladders and cable traces) is more complex.

Typically, larger spacings to the mast always create the risk of unexpected nulls in thepattern.

At smaller spacings (0.25 λ / 0.5 λ) the tower leg on which the antenna is mounted, ismainly responsible for the pattern. The principal pattern shapes of „offset“ and „bi-directional characteristic“ still exist, but compared to a cylindrical mast the patterns willhave certain irregularities and discontinuities.

The exact pattern distortion needs to be simulated by the antenna manufacturer on acase by case study.

3.1.2 Minimum macro antenna height mounting for roof top

The considerations in this chapter apply for all cases indicated in Table 30.

Antennas are frequently mounted on (flat) roofs. The recommended location for thiskind of installation is the roof edge, but for optical reasons the antennas are placedwithin the roof plane for example on the top/at the wall of an elevator shaft.Depending on the vertical HPBW and the roof shape, the roof plane may createreflections, which cause an uptilt of the resulting final pattern. So, the radiated powertowards the roof must be limited, by mounting the antenna with a sufficient heightabove the roof.

The rule is that the first Fresnel zone, which carries the main signal RF energy, shall notbe disturbed by any obstacles in the antenna near field (in this case the dominatingobstacle is the roof edge; the roof itself represents a strong reflecting plane for RFenergy). But the exact determination of the Fresnel zone is hardly possible, due to thevariable distance between transmitting and receiving antenna.

In the approach of Figure 15 (see [1.1]), the first Fresnel zone is approximized by theantenna vertical HPBW with an additional safety margin (vertical clearance margin) of20°, which means no obstacle 20° below the 3dB (HPBW) point of the vertical pattern .With ray optics, the allowed distance and height of obstacles in the beam direction ofthe antenna can be approximized to prevent antenna near field obstruction:

H>=D*tan(HPBW/2+dt+20°)Equation 7: Antenna height as function of roof geometry and vertical antenna pattern

where dt = downtilt angle

Figure 15: Mounting distances for a flat roof or a reflective plane

It is possible to set a lower vertical safety margin of 10°..15°, as long as the QoSrequirements for the site are fulfilled even with a distorted antenna pattern.

Example: 8.5° vertical HPBW, 2° dt results in easy to apply rule of thumb: H>=0.5 *D:

Distance D [m]: 5 10 >20

Required height H [m]: 2.5 5 10

Lattice tower

HPBW/2+20° H

D

omni or sectorDowntilt angle

HPBW/2+20° H

D

omni or sector

roof side view roof side view

HPBW/2+20° H

D

omni or sectorDowntilt angle

HPBW/2+20° H

D

omni or sector

roof side view

HPBW/2+20° H

D

omni or sector

roof side view roof side view

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3.1.3 Maximum skew angle for wall mounting of directional macrocell antennas

Maximum azimuth inclination angle (skew) relative to the wall perpendicular forcrosspolar antennas and vertical polarized antennas with no space diversity (to preventexcessive antenna pattern distortion):

70° - horiz. HPBW/2

for a horizontal HPBW of 33°..65°..90° ..(105°)

In the sketch, the 20° between the horizontal HPBW/2 and the horizontal line representa horizontal safety margin.

Trespassing this limit for project needs requires a measurement campaign to verify thefulfillment of QoS requirements for the site even with a distorted antenna pattern.

APPENDIX G shows the qualitative impact of antenna inclination and horizontalHPBW on horizontal antenna patterns for an ideally reflective wall (the antennaradiation characteristics strongly depends on the wall structure and roughness):horizontal antenna patterns are more and more damaged with increasing:

? antenna inclination angle with reference to the wall perpendicular

? antenna horizontal HPBW.

Further rules on skewing:

? Skewing the space diversity antennas mounted on a wall is not recommended.

? Mounting of directional antennas on building corners as shown in the sketch is notrecommended due to:

• shadowing of both Rx-antennas radiation patterns by the Tx-antenna;

• negative influence on the space diversity performance ⇐ creation ofunequal Rx radiation patterns ⇐ mirror imaged reflections

• increased installation cost and effort

3.1.4 Microcell antenna mounting rules

For microcell outdoor antennas (in-street or crossroad) the skewing rule mentioned formacrocells (3.1.3) is valid, but maybe harder to fulfill due to the possibly resultingvisual impact of the antenna installation.

? In case of continuous µcell coverage layer, it is recommended to stick to the rule asmuch as possible.

? In case of hotspot application cases (majority of microcell applications) violatingthe rule is not so critical since the service coverage is required only in a delimitedarea around the site.

The maximum distance R of a cross road omni µcell antenna from the street corner isdefined based on experience; recommended angle α is = 20° ; see Figure 16.

Figure 16: Clearance for omni µ cells

R = tan(αmax) * D = 0.36 * DEquation 8: Clearance for omni µ cells

Example: D=50 cm results in R =18 cm

(out of documents scope): engineering is mainly determined by visual aspects.

Directional microcell antennas

Omni microcell antennas;crossroad case

For picocell antenna indoor

Horiz. HPBW/2

Max. skew

Wall

20 °

Horiz. HPBW/2

Max. skew

Wall

20 °

Omni micro antenna

αmax = 20°StreetD

R

Streettop view

building

Omni micro antenna

αmax = 20°StreetD

R

Streettop view

building

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3.2 Spacing for single band antennas in dual band GSM900/GSM1800 scenario

In a GSM900/GSM1800 scenario, independent whether it is implemented with

? co-located single band cells

? or multiband cell

it is possible to use single band antennas for antenna implementation (cf. technicalsolution 2 in chapter 2.1).

In case of Alcatel Evolium A9100, A910 BTS’s, the single band antennas for GSM900and GSM1800 can be mounted side by side, horizontally or vertically, due to minimum30 dB, specified and confirmed by decoupling measurements of antennamanufacturers (e.g. in [RFS 1]); 30 dB is sufficient decoupling according to Table 28.Here horizontal side by side mounting means same antenna azimuth.

3.3 Tilt angle implementation

The mechanical down-/uptilt to be implemented must be given by the RNE to theinstallation team in the resolution of 0.5°. A higher resolution e.g. 0.1° cannot beimplemented due to the tilt scaling restriction on the antenna.

3.4 Azimuth angle implementation

The considerations below are valid for each frequency band.

An azimuth angle implementation by the installation team with a compass is highlyerroneous due to magnetic perturbation caused by ferrous constructions in the antennavicinity. Instead the following reliable procedure is proposed to reduce risk of frequentinstallation errors:

? Selection of a prominent obstacle on a good resolution paper map (e.g. building,tower, building, church etc.). If the obstacle is far away it is sufficient to consider itscenter, otherwise an edge of it (e.g. corner) which can be identified from the site.

? Map read out of the angular difference ? between the planned azimuth of theantenna and the azimuth of the identified obstacle; the same angular azimuthreference must be used as for RNP (e.g. N over E).If no good resolution paper map is available, the azimuth to the obstacle can becalculated geometrically with the GPS coordinates of the obstacle (must beretrieved) and of the site (already known).

? Implementation of ? with a tool supplied by the antenna manufacturer (not thecompass).

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ABBREVIATIONS

µBTS Evolium A910 micro BTS3GPP international standardization body (does the

work of former ETSI)A910 Evolium micro BTSA9100 Evolium macro BTSA955 V5/V6 RNP tool of Alcatel verion 5 resp. 6Anc network combining stageAnx duplexer stageANXU Antenna Network for UMTSAny combiner stageB7 BSS software releaseBBH baseband hoppingBTS Base Transceiver StationCDR call drop rateCSR call success ratedBc decibel carrierdBm decibel miliwattDL downlinkEb/No bit energy to noise ratioEIRP equivalent isotropic radiated powerG3 BTS, G4 BTS (Alcatel internal) release names of Evolium

A9100 macro BTSGSM Global System for Mobile CommunicationHO handoverHP TRX high power TRX for 900, 1800horiz. horizontalHPBW half power beamwidthHSR handover success rateIM intermodulation (product)MAPL Maximum allowed path lossMHA mast head amplifierMP TRX medium power TRX for 900, 1800MRC maximum ration combiningMS Mobile StationOMC-R operation and maintenance center radioPCS Professional Customer ServiceQoS quality of serviceRF radio frequencyRFS Antenna manufacturerRNE radio network engineerRNP radio network planningRx receiveRFH/ SFH radio (synthesized) frequency hoppingTMA tower mounted amplifierTRE TRX with GMSK and 8PSK modulationTRX transceiver with GMSK modulationTx transmitUL uplinkUMTS-FDD UMTS frequency division duplexUTRA UMTS terrestrial radio accessvert. verticalVSWR voltage standing wave ratioXPD cross polar discrimination

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INDEX

1x1, 19

1x3, 19

4-Rx diversity, 34

A955, 18, 19, 24, 25, 26,

29, 30, 34, 48, 53

Additional pathloss, 29

air combining, 6, 8, 9, 25,

29, 30, 52, 58

antenna near field, 18, 45,

64

antenna pattern, 21, 29,

30, 44, 45, 46, 53

antenna selection rules, 6,

8

BBH, 19, 48

Broadband antennas, 51

clearance, 10, 18, 45

close proximity scenario,

64

decoupling requirements,

36, 37, 38, 62

directional antennas, 51

diversity gain, 56

dual band, 6, 8

Dual band antennas, 51

effective antenna height,

28

enhanced diversity

combining, 26, 56

Evolium BTS, 9, 10, 40

feeder selection rules, 14

fixed electrical tilt, 53

frequency bands, 50

Friess, 16, 17, 52, 53

G4 BTS, 16, 17, 48, 56

interference mechanisms,

6, 36, 38, 61, 62

interference scenarios,

36, 61

Intermodulation, 36, 63

link budget, 14, 15, 16,

17, 26, 29

mast height, 18

mechanical downtilt, 53

MRC combining, 56

narrow beam, 8, 11

omni antenna, 51

polarization diversity, 28

Polarization Rx diversity,

57

remote electrical tilt, 54

Sector antennas, 51

SFH, 19, 48

Space Rx diversity, 27, 56

TMA, 6, 12, 13, 14, 16,

17, 48, 52, 53

transmitter noise, 62

triple band antenna, 51

Tx diversity, 31

variable electrical tilt, 8,

53

visual impact, 8, 9, 12, 25,

29, 46, 53, 58

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APPENDIX A FREQUENCY BANDS

System TotalBandwidth

Uplinkfrequencyband

Downlink frequencyband

CarrierSpacing

Internet Link Chiprate

GSM 450 450.5-467.5MHz

479-496 MHz

GSM 850 2x25MHz 824-849 MHz 869-894MHz 200 kHz notapplicable

GSM900 2x25MHz 890-915 MHz 935-960MHz 200 kHz www.3gpp.org/ notapplicable

EGSM 2x35MHz 880-915 MHz 925-960MHz 200 kHz www.3gpp.org/ notapplicable

R-GSM 876-915 MHz 921-960 MHzGSM1800 2x75MHz 1710-

1785MHz1805-1880MHz 200 kHz www.3gpp.org/ not

applicableGSM1900 1850-1910

MHz1930-1990 MHz

PCS 1900(USA)

1850-1910MHz

1930-1990MHz

IMT-2000(UMTS FDD)

2x60MHz 1920-1980MHz

2110-2170MHz 5 MHz www.3gpp.org/ 3.84 Mcps

UMTS TDD 20MHz +5MHz

1900-1920MHz(UL+DL)

2020-2025MHz(UL+DL)

5 MHz 3.84 Mcps

IS-95 800(cdmaOne)

2x25MHz 824-849MHz 869-894MHz 1.25 MHz 1.2288Mcps

IS-95 1900 2x60MHz 1850-1910MHz

1930-1990MHz 1.25 MHz 1.2288Mcps

IS-136 800US-TDMA

2x25MHz 824-849MHz 869-894MHz 30 kHz

IS-136 1900TDMA

2x60MHz 1850-1910MHz

1930-1990MHz 30 kHz

D-AMPS 850 824-845 MHz 869-890 MHzD-AMPS 1900 1850-1910

MHz1930-1990MHz

E-AMPS 824-849 MHz 869-894 MHzETACS 871-904 MHz 916-949 MHzNTACS 915-925 MHz 860-870 MHzNTM900 890-915 MHz 935-960 MHzPDC900 940-956 MHz 810-826 MHz

Table 31: Frequency Bands

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APPENDIX B ANTENNA TYPES

The omni antenna is used in order to achieve large continuous coverage rangesespecially in homogeneous, rural, low traffic areas or as an umbrella cell formicrocellular networks [1.1].

Main advantages:

? Continuous coverage is achieved around the site.

? Antenna installation is more simple than for sector antennas.

? Better trunking efficiency (e.g. a 6 TRX omni has a higher capacity than a sectorsite 3x2; provided of course, that there is enough frequency spectrum available toallow a 6TRX omni cell)

Main drawbacks:

? No mechanical (but electrical) downtilt is possible.

? Clearance of the antenna is required in all directions: no wall mounting possible,further there are restrictions for side mounting on masts/poles (see ch. 3.1)

? The omni cell can catch a lot of traffic and get quickly in high load situation if it isnot/or can not be equipped with a sufficient number of TRX’s.

? The omni cell can create a lot of interferences and disturb the frequency reuse; theTRX’s of an omni site require a higher frequency reuse than the same TRX’s in a 3sector configuration.

Omni antennas are also offered for UMTS as macro and micro antennas.

Sector antennas/directional antennas are typically used:

? in high traffic areas to increase capacity with sectorized sites;

? to focus on special areas (road coverage, indoor coverage);

? to achieve low coverage in regions of low interest (e.g. forest).

Main advantages:

? Electrical downtilt and mechanical downtilt are possible.

? Wall mounting is possible.

? Higher capacity per site can be achieved.

Drawback: more hardware (TRX’s) is required.

Typical parameters: gain = 17dBi, horiz. HPBW = 65°…105°, vert. HPBW = 8.5°

Dual band antennas are characterized by being suitable for two frequency ranges andhaving two separated input connectors; e.g. GSM900/GSM1800, GSM1800/UMTS,GSM900/UMTS; GSM 850/GSM 1800

Currently dual band antennas are mostly offered as sector antennas.

A GSM900/GSM1800/UMTS triple band antenna combines three antennas inside oneradome.

Broadband antennas serve the specified frequency range with only one antenna insidethe radome.

E.g.: GSM1800/GSM1900/UMTS or GSM 900/GSM1800/UMTS (frequency range:890-2170 MHz)

Main advantages:

? Possibly cheaper price than the respective dual band/triple band antennas;

? Only a single feeder cable per antenna branch needed;

Omni antenna

Sector antenna

Dual band antenna

Triple band antennas

Broadband antennas

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? No diplexer at antenna side required (but if the broadband antenna is used as adual band antenna, an additional diplexer at BTS side is necessary per antennabranch).

Main drawback: identical antenna characteristics for all bands, e.g. no differentelectrical downtilt possible.

A broadband antenna shall be selected instead of a dual band antenna only ifcommercially required (if cheaper).

Polarization is defined as the direction of oscillation of the electrical field vector. Dualpolarized antennas are used to integrate two RX antennas in one, reducing thenecessary number of antennas on site (gain of space and esthetic). Used with aduplexer, they permit the integration of the TX path on the same antenna. Used withair combining, one TRX can be associated with one polarization direction.

Dual polarized antennas are offered only as sector antennas (and not omni).

Can be offered as single band, dual band, broadband or triple band antennas.

They are characterized by esthetical design, suitability for indoor wall/ceiling mounting,low dimension and light weight. Their installation is quick, easy, and unobtrusive. Theycan be omni, directional, single and dual polarized; they are offered in all frequencyranges.

For repeater applications antennas with a high directivity such as Yagi antennas areused for the link between the donor cell BTS and the repeater.

APPENDIX C ANTENNA SYSTEMS OPTIONS

A tower mounted amplifier (TMA) can be used at a BTS/Node B to improve (i.e.reduce) the effective receiver system noise figure when a long length of feeder cable hasto be used, due to high tower/mast heights. The reduction in the receiver system noisefigure means an improvement in the uplink power budget. This can be interpreted ascompensating the losses between the antenna and the input of the base station: of thefeeder+jumper cables, connectors, diplexers, filters ([1.3], [1.6]).

Within the TMA, the duplexer separates and recombines the signals on the Rx and Txpaths. It also provides sufficient out-of-band filtering and isolation between the two paths(min 30 dB isolation). Only the RX signal gets amplified by a low-noise amplifier insidethe TMA, thus, improving the quality of the UL branch; the TX signal is bypassed to theantenna.

For RX or RX/TX antenna diversity operation, the configuration has to be doubled. Thismeans that for each antenna, one TMA unit is required (see figure). If the two units are inthe same housing, it is called dual TMA.

TMA usage in multiband configurations is possible only if the signals applied to eachantenna are single band signals (i.e. the TMA module which is used per antenna is onlysingle band).

The DC supply of the TMA is done via the RF feeder cable from the Bias-T included in theNode B's antenna unit ANXU.

In order to calculate the overall noise Figure of a reption chain, the Friess Formula isused. Equation 9 gives an example (cf. [1.3]) with TMA and no jumper cables:

DXcableTMA

BS

cableTMA

DX

TMA

cableTMAtot ggg

ngg

ng

nnn

⋅⋅−

+⋅

−+

−+=

111

Equation 9 Friess Formula with TMA

with 1010elementNF

elementn = and 1010elementG

elementg =

Dual polarized antenna

Microcell antenna

Picocell antenna

Repeater antennas

TMA

Friess Formula

X900

BTS

TMA TMA

Feeder

Jumper

X900

BTS

TMA TMA

Feeder

Jumper

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where NFelement is the noise figures in dB and Gelement is the gain in dB of thecorresponding element (note that a loss is a negative gain!). The index “element” canbe TMA, cable (denotes cables and connectors, here excluding jumper cables), DX(denotes diplexer or filter) or BS (denotes node B). If there are no diplexers or filters inthe chain, nDX and gDX are set to 1.

In case there is no TMA, the Friess Formala is given in Equation 10:

DXcable

BS

cable

DXcabletot gg

ng

nnn

⋅−

+−

+=11

Equation 10 Friess Formula without TMA

APPENDIX D OVERVIEW ON ANTENNA DOWNTILT

With introduction of downtilt, the antenna signal in the main beam direction is focusedbelow the horizon. Downtilt can be achieved mechanically, electrically or with acombination of the two; downtilt can be controlled remotely for certain antenna types.

Downtilt improves outdoor and indoor coverage probability close to the site, while witha certain distance away, the coverage probability gets lower; it reduces co-channelinterferences by reducing the cell radius or by maintaining cell radius (and reducingthe overshoots over the planned cell range); it adjusts cell borders for optimumhandovers and removes insular coverage.

Benefit: it is achieved by the mounting hardware (cost-effective); no antenna swap isnecessary.

Drawbacks:

? Non-regular coverage reduction is achieved (maximum interference reduction inmain direction only).The adjusted downtilt angle is only valid for the main direction of the horizontalradiation pattern. In the tilt axis direction (+/-90° from main beam) there is nodowntilt at all. Further, the resulting gain reduction depends on the azimuthdirection. This effect is considered in A955 V5/V6.

? Distortions in horizontal antenna pattern in case of mechanical tilt cause largegain variations i.e. large signal fades ; risk of call drops is increased (see [RFS 2]).

? The polarization plane is also rotated.

? Frequent mechanical tilt adjustment (done onsite!) has bad visual impact (siteoperation outage).

Benefit: the adjusted downtilt angle is constant over the whole azimuth range, so alllobes are equally tilted; this yields an equal reduction of all interferences and a regularreduction of coverage.

Drawback: electrical tilt adjustment is not possible (antenna swap necessary associatedwith visual impact, site operation outage).

Benefits:

? Easy cell size tuning according to capacity evolution while minimizing co-channelinterferences;

? For electrical tilt adjustment the antenna remains unchanged =>

• No outage on site operation;

• Cost saving through reduced inventory management.

Drawbacks :

? Variable electrical tilt adjustment must be done via control button at the antennaradome (i.e. installer must climb up);

? Higher price.

Scope of downtilt

Mechanical downtilt

Fixed electrical tilt

Variable electrical tilt

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Benefits (cf. [RFS 2]):

? For electrical tilt adjustment the antenna remainsunchanged =>

• No outage on site operation;

• Cost saving through reduced inventory management.

? For time being, tilt adjustment is done from the base of the antenna tower via acontrol unit linked with a cable to a laptop. For the next BSS releases (B8?) it isforeseen to implement an interface to the OMC-R=>tilt tuning without sendingcrew onsite, i.e reduction of network optimization costs especially for badlyaccessible sites.

? Provision of easy adaptation coverage versus capacity and interference control;

? Control of cells overlapping;

? No limitation on frequency of tilt tuning;

? Compatible with future dynamic capacity allocation.

Drawback: possibly elevated price.

A high first upper side lobe suppression is a mandatory feature for electrically tiltedantennas. The drawback of increased antenna length has only a small impact on sitegeometry and can be tolerated.The first upper side lobe, which is typically in the range of up to max. 20°, is critical forinter-cell interference.

Electrical tilt adjusts antenna footprint: it minimizes inter-cell interference whilemaintaining cell coverage. Both coverage and inter-cell interference are trafficdependent =>optimum tilt value to control inter-cell interference is traffic dependent.

In inhomogeneous traffic scenarios:

? Reduce footprint of highly loaded cells by increasing electrical tilt.

? Enlarge footprint of lower loaded cells by decreasing electrical tilt.

Scope:

? Avoid overload in single cells

? Even traffic distribution between cells

Table 32 below presents the application area of UMTS adjustable tilt:

Remote electrical tilt Variable electrical tilt Fixed electrical tiltInhomogeneous trafficdistribution

Inhomogeneous trafficdistribution

Homogenous trafficdistribution

High time dependency oftraffic

Low time dependency oftraffic

Very low time dependency oftraffic

Table 32: Application area of UMTS adjustable tilt

APPENDIX E OVERVIEW ON ANTENNA DIVERSITY

The purpose of using diversity is to reduce short-term fading effects, such that anacceptable level of performance (receiver sensitivity) can be achieved, without havingto increase the transmitted power or the bandwidth.

The principle relies on the combination of two or more signals, containing the sameinformation, which are at least partially decorrelated. If two signals of the same levelare completely decorrelated, the probability that both signals experience the samedepth of fade is only the square compared to the probability for one signal. Thereforethe signal reliability is increased.

Remote electrical tilt

Upper side lobe suppression

UMTS; Tilt adjustment foroptimum traffic distribution

Purpose

Principle

Rx Diversity systems

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The diversity types which are subject of this document are:

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Applicable inDiversity type CategoryGSM UMTS

Rx diversity space div. yes yespolarization div. yes yesspace div. + polarization div. yes n.a.

4-Rx diversity space div. + polarization div. n.a. yesTx diversity space div. no yes

polarization div. no yesFigure 17: Overview on diversity types

Only two Rx diversity systems are subject of this document:

? For space diversity, the decorrelation is achieved by receiving the signals with twospatial separated (horizontally or vertically) antennas.

? For polarization diversity, decorrelation is achieved by using antennas with differentpolarization planes (horizontal/vertical or cross, i.e. +/-45°).

To achieve a maximum Rx diversity gain it is required to have [2.1]:

? high signal decorrelation between receiver paths

? low signal level difference between receiver paths (due to the maximum ratio orenhanced diversity combining methods in the Alcatel BTS which weighten thesignals in proportion to their signal/noise ratio, see APPENDIX E ).

With space diversity better signal decorrelation can be achieved.

The G3 receivers in the Alcatel BTS use the maximum ratio combining (MRC) method.

The MRC method does not reduce the interference level received from other mobilesusing the same frequency(ies) (co-channel interference) or from adjacent frequencies(adjacent interference). It only improves the received signal by steering a beam into thedirection of the mobile; it estimates the phase difference between the two antennas,corrects this phase difference, weightens the signals in proportion to their signal tonoise ratio before the co-phased signals are added; there is coherent addition of thesignals and incoherent addition of the noises; this increases the signal to noise ratio.

MRC combining offers:

• Very good performance under noise limited conditions; for diversity gain seeTable 23: 3 – 6 dB improvement compared to no antenna diversity.

• Less improvement under interference limited condition;, up to 3 dB diversitygain compared to no diversity.

The G4 receivers in the Alcatel BTS (G3 BTS or G4 BTS) use the enhanced diversitycombining method. This feature is available from B6.2 BSS software release onwards.

The enhanced diversity combining uses several algorithms:

? There is an beam forming algorithm to improve the received signal by steering abeam into the direction of the mobile (like in MRC method).

? But moreover, there is an algorithm to reduce interference: it cancels interferers bysteering a null into their directions (it estimates the phase difference between thetwo antennas for the interfering signals and then, it rejects these interfering signalsby adding the signals with an inversed phase).

Enhanced diversity combining gives its best efficiency when the useful signal and theinterfering signals come from different directions.

? Principle: during a deep fade at one Rx antenna location, the fade will not be assevere at the other Rx antenna location, if the two Rx antennas are sufficientlyseparated. For space diversity, reflections are not so important.

? Advantages:

MRC combining

Enhanced diversity combining

Space Rx diversity

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• UL improvement (optimum diversity gain for wide area);

• Space diversity works better than polarization diversity in rural environment(characterized by wave propagation with few reflections).

? Drawback: possibly large space requirement for sufficient Rx antennaseparation=> expensive tower/mast construction.(An alternative can be to mount the diversity Rx antennas on 2 separate polesconstructed in the required distance; equal feeder length required).

? Principle: polarization decorrelation of the different signal rays which encounterdifferent multipath reflections while traveling between the MS to the BTS. So thereflections are mainly important for polarization diversity, since they change thewave polarization.

? Advantages:

• UL improvement (diversity gain);

• 2 Rx antennas with different polarizations mounted under the same radome;

• No need for large site structures as in case of space diversity.

Drawback: effective only in high multipath environments.

The aim of transmit diversity is to alleviate fast fading and therefore to increase thecapacity of the downlink transmission.

The transmit antenna diversity technique consists in using at the transmitter severalantennas, broadcasting complementary signals. To implement the TX diversity feature,two power amplifiers per sector are needed. Adding a power amplifier will double theavailable output power (3dB gain on output power); this gain of 3dB is not a diversitygain in the original sense of the word, but merely linked to the second power amplifier.

Several transmit diversity techniques have been standardized in the FDD mode ofUMTS for two transmit antennas:

? open loop transmit diversity

• TSTD, Time Switched Transmit Diversity (for the DL synchronization channel)

• STTD, Space Time Transmit Diversity (for traffic channels)

? closed loop transmit diversity mode 1 and mode 2.

Antenna transmit diversity is provided optionally for UMTS-FDD Node B, but it ismandatory for the MS. It can be switched-on on a per channel basis.The MS (with omni, vertical polarized antenna) uses the maximum ratio combiningmethod to combine the 2 DL signals.

Support by HW and SW: Open and closed loop are supported by Evolium Node B; butin R1 only 'closed loop Tx diversity mode 1' is implemented. In R2 neither open loopnor closed loop TX diversity are implemented.

The isolation between ports is the attenuation between the branches in near field. Incontrary the cross-polar discrimination is the attenuation between the two branches infar field.

Antenna inter-port isolation: Denotes the ratio in dB of the power level applied to oneport of a dual polarized antenna to the power level received in the other input port ofthe same antenna. Typical value is minimum 30 dB.

Cross polar discrimination (XPD): The difference in dB between the co-polarized mainbeam signal and the cross-polarized signal measured within an angular zone inazimuth of twice the maximum half power beam width of the frequency band. E.g. fora 65° hor. HPBW antenna , XPD is measured both in the main axis and at 60° openingangle. Typical value is 30…35 dB minimum.The better the cross polarized discrimination is,

? the better the diversity gain of the antenna;

Polarization Rx diversity

UMTS-FDD Tx diversity

Important characteristics forcross polar antennas

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? the lower the level of disturbing signal (coming from the opposite slant) is, in orderto insure a safer reception.

APPENDIX F PRINCIPLE OF AIR COMBINING

The idea of air combining is to combine transmitted signals in the air and not with anBTS internal combiner, in order to avoid combining losses. Each TX-signal will betransmitted via a separate antenna. With air combining combiner losses can be saved(depending on the number of saved combiner stages, i.e. on the number of TRX’s),resulting in a lower path loss in the DL. This results in an improved coverage range formacrocells or in an improved indoor coverage for microcells.

Air combining can be realized with:

? two sector or omni antennas (vertical polarized)

? one cross polar antenna transmitting different carriers on +-45°.

Thus cross polar antennas allow air combining configurations with a single antenna.

Remark: Air combining with horiz./vert. polarized antennas is not recommended, sincethere are losses of typ. 3 dB on the horizontal polarization direction, assuming avertical polarized MS antenna (see also ch. 2.7.3).

APPENDIX G ANTENNA PATTERN DISTORTION FOR DIFFERENT MOUNTINGSCENARIOS

Refer to [KAT 1].

Regarding Figure 18:

Spacing 0.5 λAn increase of the spacing to 0.5 λ creates a bi-directional pattern perpendicular tothe line antenna – mast, which becomes more characteristic with bigger mastdiameters. This pattern shape provides 2-3 dB more gain and could be applied for thecoverage of highways and railway lines.

Spacing 0.75 λAt a spacing of 0.75 λ a further beam grows in the direction of the antenna; atridirectional pattern is formed.

Spacing 20 λThe number of beams becomes greater and the depths of the corresponding minimabecome smaller as the spacing is increased; the pattern changes back into an omnicharacteristic. However the influence of the mast can still be recognized up to spacingsof 20-25 λ. Such a spacing of 20 lambda is not feasible due to heavy visual impactbut shows the behaviour from a qualitative p.o.v.

Regarding Figure 19, Figure 20:

The antenna radiation characteristics strongly depends on the wall structure androughness. Figure 19, Figure 20 are given for an ideally reflective wall (such asconcrete walls or aluminum covered facades.

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Figure 18: Typical radiation pattern distortions of mast side mounted omni antenna

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Figure 19: Typical horizontal radiation pattern distortions of wall mounted GSM900 directional antennas;22 ° inclination

Figure 20: Typical horizontal radiation pattern distortions of wall mounted GSM900 directional antennas;45° inclination

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APPENDIX H INTRA-/INTER-SYSTEM COMPATIBILITY

Intra-system compatibility guarantees no disturbances due to interference mechanismswithin the same communication system

? 1 system, 1 operator

? 1 system, 2 operators (e.g. UMTS-UMTS co-siting on multi operator site)

Inter-system compatibility guarantees no disturbances due to interference mechanismswithin the different communication systems

? 2 system, 1 operator (e.g. GSM1800-UMTS co-siting operated by same operator)

? 2 system, 2 operator (e.g. GSM1800-UMTS co-siting on multi operator site)

The following interference scenarios are generally valid for any type of cellular systems.Two different cellular systems shall cover the same area. The co-existence of twosystems or even site sharing means, that there are 4 possibilities that interference arise.

Serving Base Transceiver Station Interfering Base Transceiver Station

I S S I

S I

Figure 21: Two cellular systems covering the same area

The different combinations of interference disturbing the serving BTS and the MS,which is dedicated to the serving BTS, is shown in the following picture. Someabbreviations are used: S=Serving; I=Interfering; green=carrier; red=interferer signal


I S S I

S I

I-BTS DL à S-BTS UL


I S S I

S I

I-BTS DL à S-MS DL

Intra-/Inter-system compatibility

Interference scenarios

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I S S I

S I

I-MS UL à S-BTS UL


I S S I

S I

I-MS UL à S-MS-DL

Figure 22: Interference scenarios

The four combinations of Figure 22 are:Transmitter/Interference source

Link creatinginterference

Receiver Link which isinterfered

BTSàBTS I-BTS DL S-BTS ULBTSàMS I-BTS DL S-MS DLMSàBTS I-MS UL S-BTS ULMSàMS I-MS UL S-MS DL

Table 33: Interference scenarios

Planning a radio network mainly means planning site locations for transceiver stations.Therefore BTS à BTS interference problems can be reduced or avoided.

The BTSàMS interference comes from a interfering BTS. Normally, the influence onplanning this configuration is low, if another operator handles this network.

The MS à BTS situation is only taken into consideration by planning the BTS, with all itsattributes like antenna height, antenna orientation, and so on.

The location of a mobile user can have a big variety. In the MSàMS scenario, it is notavoidable, that two mobile users of different systems get close to each other.

So the focus is on combating the BTS à BTS interference scenario.

Co-location of base stations may cause interference resulting in performancedegradation. In order to minimize this performance degradation to an acceptabledefined level, decoupling requirements between the systems have to be met.

The most important interference mechanisms are:

Transmitter noise/ spurious emissions

The transmitter noise floor or transmitter spurious of system "A" within the receive bandof system "B" causes interference of system "B´s" receiver and vice versa. This could beavoided by increasing the stop band attenuation of system "A´s" antenna network inthe transmit path for the receive band of system "B", or by increasing decouplingbetween the two systems, either the air decoupling or the decoupling provided bydiplexer.

Receiver blocking

Interference mechanisms

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Transmit signals of system "A" are blocking the receiver of system "B" and vice versa.This could be avoided by increasing the stop band attenuation of system "B´s" antennanetwork in the receive path for transmit frequencies of system "A", or by increasing thedecoupling between the two systems (air or diplexer decoupling).

Intermodulation (IM) products

Significant intermodulation products are generated in nonlinear devices (especiallymixers and amplifiers but also connectors), if two or more strong signals are applied.

Intermodulation problems due to co-location might rise, if transmit carriers from theco-located system "A" generate intermodulation products falling into a used receivechannel of system "B" or vice versa. Also a combination of transmit frequencies of bothsystems might fall into a used receive channel of either system "B" or system "A."

? IM can occur within one system, without co-location of any other system (1 system,1 operator); this is an intra band IM; condition: both frequency signals are appliedon the same duplexer

? IM can occur between 2 co-located systems; condition: antenna and/or feedersharing (there are no IM between 2 co-located systems if this condition is not given)

• Intra band IM: can happen on multi operator sites (e.g. UMTS-UMTS co-location: 1 system, 2 operators)

• Inter band IM: can happen on multi operator sites (e.g. GSM1800-UMTS co-location: 2 systems, 2 operators ) or on single operator sites (e.g.GSM1800-UMTS co-location- 2 systems, 1 operator)

General formula for IM products:

fIM = m • f1 + n • f2 with m, n = 0, +1, +2, +3, ...

where the order of the IM product=|m|+|n|; only positive fIM make sense.

Only low order IM products are critical; the higher the IM order, the less their powerand the less critical the IM products are.

The reference point for IM products inside a used Rx channel is the BTS antennaconnector. As long as the signal level of the interfering critical IM product is well belowthe systems noise floor, almost no receiver degradation, and thus no problem due toIM will occur.

The total intermodulation level compared to a power-rating of 1 mW is expressed indBm:

IM = 10 log PIMP3 [dBm] .

On the other hand, dBc is defined as the ratio of the third order intermodulationproduct to the incident Tx carrier signal power:

IM = 10 log(PIMP3/PTx ) [dBc] .

APPENDIX I MISCELLANEOUS

For outdoor macrocell antennas it is possible to have the following cases:

? tower/mast/pole: top mounting or side mounting;

? roof: top mounting;

? wall: side mounting.

Microcell outdoor antennas used for in-street coverage are mounted on the wall/polebut below rooftop and the ones used for crossroad coverage are mounted on a pole.

The antenna radiation behaviour is splitted in a near and a far field characteristic.Typically the antenna radiation characteristics given in antenna catalogues are valid forthe far field. The near field antenna radiation characteristic depends on tower /mast/wall construction elements and the antenna dimensions; it is not depending on the farfield radiation characteristics.

Antenna mounting location

Antenna near and far field

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There should not be any obstacles within the near field since the antenna diagram isthen severely disturbed.

The range of the antenna near field is dependent on the maximum size of the antennaaperture D (i.e. antenna length) and the wavelength λ. It can be estimated with thefollowing deterministic formula:

Rmin=2D²/λ

Typical values for macro antennas are:

GSM900 (D = 2.5 m; λ= 33 cm; Rmin = 38 m)

GSM 900 (D = 2.0 m; λ= 33 cm; Rmin = 24 m

GSM1800 (D = 1.3 m; λ= 16 cm; Rmin = 21 m)

UMTS (D = 1.3 m; λ= 14,6 cm; Rmin = 23 m)

An indoor mobile is connected to micro BTS 1, while another mobile being connectedto micro BTS 2 might turn around the corner and have sudden direct line of sightcondition to micro BTS 1. In such a scenario there is a high risk of µBTS receiver in-band-blocking. In order to achieve a sufficient minimum coupling loss between mobileantenna and BTS receiving antenna the mounting height has to be accordingly high,taking into account the following two basic items:

? In order to increase the minimum coupling loss between MS and BTS, the antennashould be positioned as high as possible.

? With increasing mounting height the interferer potential will be increased,especially since microcells often are planned with a reduced Reuse Cluster Size.

END OF DOCUMENT

Close proximity scenario (µ cell)

antenna system planning

Documents

geometrical

rx eb n0

close proximity

tx insertion

good fringe

reduced inventory

cross polar

2rx diversity