go np04 e1 1 gsm coverage planning-60(new)
Post on 03-Apr-2018
215 Views
Preview:
TRANSCRIPT
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 1/60
GSM Coverage Planning
ZTE university
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 2/60
Contents
Overview of coverage planning
Link budget
Propagation model
Scale estimation Coverage enhancing technology
The common coverage issues Q&A
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 3/60
1. What is the purpose of coverage planning?2. What is the work content of coverage
planning?
3. What is the input of coverage planning?
4. What is the output of coverage planning?
1. Overview of coverage planning
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 4/60
1. What is the target of coverage planning?
Do the link budget and radius estimation for the targeted
coverage area so as to get to know the site scale and site
deployment which satisfy the KPI. Besides, if a digital map
is available, an adjustment can be done to the sites
according to the results of coverage simulation.
It is a must to have a three dimensional
digital map (Planet/EET) which coversthe whole targeted coverage area. Degree
of accuracy:
For urban areas: not lower than 20m;
For rural areas: not lower than 50m.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 5/60
2. What is the work content of coverage planning?
Clarify the
input
Site
deployment
Link budget
Propagation
modelcalibration
Coverage
simulation
Scale
estimation
Coverage
plannin
g
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 6/60
3. What is the input of coverage planning?
•Which cities and major roads will be covered?
•What are the categories of scenarios according to theradio environment?
•What is the coverage range of each scenario?
The coverage requirements of each scenario:
•Coverage level
•Coverage probability
•Carry out a test and calibrate the parameters of the
propagation model.
•No test is carried out, and the parameters of the
standard propagation model are adopted.
•The equipment types, which will be adopted for the bidding,
depends on the market strategy.
•The biggest site configuration depends on the frequency bands and
the frequency resources.
•Is a Planet three-dimensional digital map available? The coverage
simulation can not do without the map.
•What about the application of the different kinds of coverage
enhancing technologies? ……
The size and range of the
target coverage area
KPI The coverage KPI
The parameters of the
propagation model
Others
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 7/60
4. What is the output of coverage planning?
Site scale
Site
deployment
Coverage
simulation
The balanced
budget of
uplink/downlink
power
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 8/60
1. Why is link budget needed?
2. What is path link balance?3. How can we judge a link is limited?
4. What is the result if a link is limited?
5. What is link gain and link loss?
6. What is slow fading?
7. What is fast fading?
8. What is coverage probability?
9. What is margin?
10. What kind of margin should be considered for the link budget?
11. What factors should be taken into consideration to decide the slow
fading margin which is frequently used?
12. What is design signal level and acceptance level?
13. What are the categories of combiner loss which are frequently come
across in link budget?
14. What factors should be taken into consideration to decide the power
of the set-top unit of ZTE series equipment?15. What factors should be taken into consideration to decide the
antenna and feeder loss of ZTE series equipment?
16. What is TMA?
17. How to choose the a suitable type of antenna?
18. How is the uplink/downlink budget calculated?
19. How to avoid the unbalanced link in network planning?
2. Link budget
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 9/60
1. Why is link budget needed?
The purpose of doing the uplink/downlink budget is toestimate the uplink/downlink coverage ability of the
system and to get the allowed maximum path loss of a
balanced link through an analysis of the factors which
influence the uplink/downlink signals during thetransmission.
The link budget is used to see how the uplink/downlink
borders of a cell is covered.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 10/60
2. What is link balance?Strictly speaking, link balance means that the difference of
the path loss of the uplink radio link and that of thedownlink radio link is“0”.
Generally speaking, it is considered that there is a rough
link balance if the allowed maximum path loss difference
between the uplink and the downlink is no more than 2dB
when the link budget is calculated.
Downlink
coverage
Uplink coverage
Uplink coverage
=
Downlink
coverage
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 11/60
3. How can we judge a link is limited?
Uplink limited
Uplink coverage < Downlink coverage,that is,
The allowed maximum uplink path loss < The
allowed maximum downlink path loss
Downlink limited
Downlink coverage < Uplink coverage,that is,
The allowed maximum downlink path loss < The
allowed maximum uplink path loss
Uplink coverage
Downlink coverage
The part of invalid
downlink coverage
Downlink coverage
Uplink coverage
The part of invalid
uplink coverage
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 12/60
4. What is the result if a link is limited?
Uplink limited
In areas with problems, the handset has
signals but it can not originate a call;When the subscriber moves towards the
borders of a cell (areas with weak signals),
there may be unilateral conversations or call
drops.
When the subscriber moves from any other
area towards the uplink limited area which
is an area with problems, the success rate of
inward handovers of the cell will be affected.
Downlink limited
In the areas with problems, the handset is in
the coverage holes of the site, and it can not
originate a call.
When the subscriber moves towards theborders of a cell (areas with weak
signals), there may be unilateral
conversations or call drops.
Uplink coverage
Downlink
coverage
Areas with
problems
Areas with
problems
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 13/60
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 14/60
6. What is slow fading?
When the signals are transmitted, they will be blocked by the buildings and the
uneven land forms. In the areas where the signals are blocked, the shadow of
electromagnetic waves will be formed. As a result, the signal strength will be
weakened. This is called Shadow Fading, a kind of fading of signals, which is
caused by the shadow effect.
The signals go through a slow and random change within the range of dozens of
wavelengths, so the statistical counting obeys the rules of lognormal distribution.
Therefore, Shadow Fading is also called Slow Fading.
In English, it is called Slow Fading,or
Log-normal Fading,or Shadow
Fading.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 15/60
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 16/60
Under the sameconditions, the areacoverage probabilityis larger than theedge coverageprobability. The twocan be mutually
transformed accordingto some rules in math.
8. What is coverage probability?
Coverage probability refers to how large the probability is that the received signal
of the terminal is larger than the threshold at the coverage borders of the cell (or within the coverage areas).
Coverage
probability
The edge coverage probability:The percentage of the cell borders whose
received signal is larger than the threshold.
The area coverage probability:The percentage of the areas whose received
signal is larger than the threshold.
The threshold level of the cell borders:-90dBm The threshold level of the cell borders :-90dBm
The test is carried out along the covered cell
borders. The edge coverage probability refers to the
percentage of samples, of which the level is at least
- 90dBm.
The test is carried out along the paths of the covered areas
of a cell. The area coverage probability refers to the
percentage of samples, of which the level is at least -
90dBm.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 17/60
9. What is margin?
When the radio signals are transmitted, they will have an
attenuation caused by different kinds factors of the radio
environment, for example, shadow effect, multi-path effect,
and so on. Therefore, the influence caused by these factors
should be taken into consideration when the design of radio
network starts. At the stage of network planning, some power
can be reserved to resist the possible attenuation. The
reserved power is called margin.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 18/60
10. What kind of margin should be considered for the
link budget?--1
GSM is a kind of interference limited system. The received power should not only resist the noises
but also resist the co-channel/adjacent channel interferences which are caused by the frequency
reuse so as to ensure the quality of the signals. The power reserved to resist the interference is
called interference margin.
Usually it is 3dB.
1In order to ensure that the site can cover the cell borders with a certain probability,
the site must reserve some transmission power so as to overcome Shadow Fading.
So the reserved margin is called Shadow Fading margin or Slow Fading margin.
3
The multi-path effect of the transmission of radio signals will result in the fast fading of signals, so
the quality of signals will be affected. For GSM system, it resists Fast Fading by making use of a
series of technologies, including interleaving coding, frequency hopping, diversity reception,
adaptive equalization, and so on. Besides, at the stage of network planning, some design margin
should be reserved to resist Fast Fading. This is called Fast Fading margin. Usually, it is 3dB.
2
Slow Fading margin
Fast Fading margin
Jamming margin
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 19/60
10. What kind of margin should be considered for the
link budget?--2
Loss caused by the penetration of a car refers to
the attenuation which occurs when the radio
waves penetrate the car. It is equal to the
difference value when the median value of the
field strength of the signals outside the car and
that inside the car are compared.
Usually, it is 6~8dB.
4Body loss refers to the kind of loss which is caused by
signal blocking and absorption when the handset is held
quite close to the human body. Usually, for voice service, it
is 3dB;and for data service, it is 0dB.
6
Loss caused by the penetration of a building refers to the
attenuation which occurs when the radio waves penetrate theexterior structures of a building. It is equal to the difference value
when the median value of the field strength outside the building
and that inside the building are compared. The value related of
this kind of loss is closely related to the materials and thickness
of the building.
5
Body loss
Loss caused by the
penetration of a building
Loss caused by the
penetration of a car
Classification of
different areas
Typical
penetration loss
value
Dense urban 18~22Medium urban 15~20
Suburban areas
and rural areas
10~15
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 20/60
11. What factors should be taken into consideration to
decide the slow fading margin which is frequently
used?
Area TypeArea Coverage
Probability
Edge Coverage
Probability
Slow Fading
Margin (dB)
Dense Urban
Sigma=10dB
75% 54% 1
85% 69% 5
90% 80% 7.7
95% 88% 11.7
Medium Urban
Sigma=8dB
75% 50% 0
85% 66% 3.2
90% 75% 5.5
95% 86% 8.7
Suburban/Rural /Road
Sigma=6dB
80% 50% 0
85% 60% 1.6
90% 71% 3.4
95% 84% 5.9
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 21/60
12. What is design signal level and acceptance level?
The lowest level required SSmin_req
It refers to the lowest level required for making calls in real situations (outdoor/indoor/in a car).
On basis of the receiver sensitivity, it takes the following factors into consideration: Fast Fading
margin, interference margin, body loss, loss caused by the penetration of a building which is
relevant to a indoor subscriber or loss caused by the penetration of a car which is relevant to a
subscriber inside a car.
Design level SSdesign
In order to ensure a certain probability, it is necessary to consider the Shadow Fading
margin on basis of the lowest level required or the acceptance level. Then, the level value is
called design level. In other words, at the network planning stage, it is a must to consider
the possible influence exerted by Shadow Fading over the signal coverage. The purpose is
to ensure the network coverage probability.
Acceptance level SSacceptance
Usually, in the bidding documents or the contract, the client will mention the DT coverage KPI,
including the requirements for level value and coverage probability which DT should meet.
Then, the required level value which DT should reach is called the acceptance level by us.
However, if the client does not have any requirements for the acceptance level, we should
make a suggestion. Usually, it is considered that SSacceptance should be equal to SSmin_req
(SSacceptance = SSmin_req).
1
2
3
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 22/60
V2 series combiner loss
13. What are the categories of combiner loss which are
frequently come across in link budget?
1
Combiner 900M(d
B)
1800M(d
B) CDU 4.4 4.6
CEU 3.5 3.5
CEN 5.3 5.5
MCDU 4.4 4.6
ECDU 1 1
ECU 3.5 3.5
V3 series combiner loss
Combiner 900M(d
B)
1800M(d
B)
CDU 4.4 4.6
CEU 3.5 3.5
ECDU 1 1
2
SDR series combiner loss3
For RU02 and RU02A, the COM
loss is 3dB when it is S3~S4.
Other radio frequency processing
units do not have a combiner
inside.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 23/60
14. What factors should be taken into consideration to
decide the power of the set-top unit of ZTE series
equipment?
TypeTransmiss
ion power Notes
V3
series
equip
ment
B8018 60wThe power of the set-top unit is closely related to the
configuration of carrier frequencies of the cell, the combiner
selected, and whether there is a new antenna or not. The
power of the set-top unit of GSM equipment with themodulation mode of 8PSK is about 2dB lower than that of
GSM equipment with the GMSK modulation mode.B8112 60w
M820230w(set-
top unit)
M8202 does not have a Combiner (either inside or outside).
The power of the set-top unit is always 30w(GMSK). The
power of the set-top unit of GSM equipment with the
modulation mode of 8PSK is about 2dB lower than that of
GSM equipment with the GMSK modulation mode.
M820630w(set-
top unit)
M8206 has a combiner outside, that is, ECU. If combining is
needed, it is necessary to take into account the loss of ECU
(3.5dB). The power of the set-top unit is 13w. The power of
the set-top unit of GSM equipment with the modulation mode
of 8PSK is about 2dB lower than that of GSM equipment with
the GMSK modulation mode.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 24/60
14. What factors should be taken into consideration to decide the power
of the set-top unit of ZTE series equipment? - SDR Equipment
•Now multi-carrier RU/RRU
follows the principle of equipartition of carrier power ! Carrier number RU02/RU02A RU60/R8860 RU80
GSM GMSK (W) GMSK (W) GMSK (W)
1 40 60 80
2 40 30 40
3 20 20 26.67
4 20 15 20
5 12 16
6 10 13.33
GSM
carrier
number
UMTS
carrier
number
RU60/R8860
GSM
GMSK (W)
UMTS (W)
1 1 40 20
2 1 20 20
3 1 13.33 20
4 1 10 20
1 2 20 20
2 2 10 20
The output power of set-top
unit of GSM with 8PSK
modulation is about 2dB lower
than that of GSM with GMSK
modulation.
•If the BS model configuration
for dual-carrier RU02/RU02A is
S3~S4, the loss for internal
combiner is 3dB.
1
2
GSM
single
mode
configur
ation
G/U
dual-
mode
configur
ation
For UMTS, the output power of
set-top unit per carrier must be
20W.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 25/60
15. What factors should be taken into consideration to decide the
antenna and feeder loss of ZTE series equipment? – The
Typical Antenna and Feeder Connection
Without
TMAWith
TMA
Feeder
Type 900 1800 Unit
1/2” 11.2 16.6 dB/100m
7/8” 3.88 5.75 dB/100m
5/4” 2.77 4.16 dB/100m
13/8” 2.29 3.47 dB/100m
The table here shows the typical KPI of Hansen. It is just for
your reference. For a specific project, the table should be filledin according to the actual configuration of feeder line KPI.
If the feeder loss is more than
3dB, it is suggested that a
heavier feeder line should be
used.
Type Loss Unit
Connector 0.05 dB/eachT connector 0.3 dB/each
Lightning
arrester 0.2 dB/each
TMA
insertion loss 0.5 dB
•Increase the downlink insertion loss of
the tower amplifier (downlink).• Add one T connector and two other
connectors (uplink/downlink).
• Add some 1/2 soft jumper cable
(uplink/downlink).
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 26/60
What factors should be taken into consideration to decide the antenna
and feeder loss of ZTE series equipment? – Typical Antenna and Feeder
Connection
Installation near
an antenna
1
RRU and BBU is connected
by fiber ;
RRU and antenna is
connected by 1/2” jumper.
1. 2m ½” loss for softer jumper
2. 2 connector loss
Height of
antenna(m)
Height of
RRU on
platform
(m)
Length
of 7/8
main
feeder
line
(m)
Length
of ½
jumper
(m)
Connector
+
lightning
arrester
900M(d
B)
1800M(
dB)
50 0 50 4 6+1 2.89 4.04
50 10 40 4 6+1 2.5 3.46
50 20 30 4 6+1 2.11 2.89
50 30 20 4 6+1 1.73 2.31
50 50 0 2 2 0.32 0.43
1. 2×2m ½” softer jumper loss
2. Main feeder line loss between RRU and
the antenna
3. 6 connectors loss4. 1 feeder line lightning arrester loss
The table here is only for reference, in practice please
calculate according to specific conditions!
RRU is installed on the
platform of a tower (a platform under the antenna)
,or installed at the roof and
it is lower than the antenna
;
RRU and BBU is connected
by fiber ;
RRU and the antenna is
connected in a normal way.
The length of main feeder
line is the distance between
RRU and the antenna.
The installation
position keeps a
distance from
both BBU and
the antenna.
2
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 27/60
16. What is TMA?
TMA—Tower Mounted Amplifier
Tower Amplifier is the short form for Tower Mounted Amplifier. Actually, an
amplifier which has low noises and high linearity (low noise amplifier) is installed at
the front end of the receiving system of the site, a place, which is close to the
receiving antenna. It is used to amplify the uplink signals, to improve the noise
figure of the receiving system of the site, and to improve the uplink coverage
capability.
Q:Usually, the KPI designed for the uplink gain is 12dB. Does it follow
that 12dB uplink gain should be taken into consideration when the link
budget is calculated?
A:No. Since TMA is actually a low noise amplifier. On the one handthe valid uplink signals are amplified, on the other hand, different kinds
of noises and interferences are also amplified. The actual uplink gain
generated by TMA is usually 2~ 3dB.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 28/60
17. How to choose the a suitable type of antenna?
Area Antennaheight(m)
Antenna gain(dBi)
Horizontalbeamwidth
of theantenna
Verticalbeamwidth
of theantenna
Polarizationcategories
Electrical downtilt
Dense urban 20~25 15.5~17 65 8~14 Dual-polarization
0~10 degreeelectrical downtilt
Urban areas 35~30 15.5~17 65 8~14 Dual-polarization
2~6 degreeelectrical downtilt
Suburban areas 35~40 17~18 65、90 7~10 Dual-polarization
2~4 degreeelectrical downtilt or without electricaldowntilt
Rural areas 45~50 17~18 65、90 7~10 Dual-polarization ,verticalpolarization
The electricaldowntilt is optional.
Highways or long and narrowvalleys
45~60 18~22 35 6~8 Dual-polarization ,verticalpolarization
The electricaldowntilt is optional.
If a single frequency antenna is used by a co-sited dual-band base station, the antenna selected for the 1800M
base station should be 1~2dB higher in antenna gain than that selected for the 900M base station. Usually, the
antenna of a 1800M base station is higher than that of a 900M base station by 3~5m.
If a dual-band antenna is selected, the installation space can be saved. However, the separate adjustment made
for the two networks will not be so flexible. It should be checked whether the antenna parameters of the two
frequency bands can both meet the relevant requirements.
In dense urban areas, an antenna with a lower antenna gain can be chosen if necessary.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 29/60
18. How is the uplink/downlink budget calculated?
Parameter Symbol Unit
Transmission power of
the carrier frequency A dBm
Combiner loss B dB
Output power of the
set-top unit of BTSC=A-B dBm
Feeder line connector
lossD dB
Antenna gain of BTS E dBi
Antenna gain of MS F dBi
Receiver sensitivity of MS
G dBm
Fast fading margin H dB
Interference margin I dB
Body loss J dB
Loss caused by the
penetration of a building
or a car
K dB
Slow fading margin L dB
The minimum level
required (DL)M=G+H+I+J+K dBm
Design level (DL) N=M+L dBm
Downlink enhancing
technologyO dB
The maximum
downlink path lossallowed
P=C-D+E+F-N+O dB
Parameter Symbol Unit
Transmission power of
MS A dBm
Antenna gain of MS B dBi
Antenna gain of BTS C dBi
Diversity gain D dB
Feeder line connector
lossE dB
The contribution to
sensitivity made by TMAF dB
Receiver sensitivity of BTS
G dBm
Fast fading margin H dB
Interference margin I dB
Body loss J dB
Loss caused by the
penetration of a building
or a car
K dB
Slow fading margin L dB
The minimum level
required (UL)M=G+H+I+J+K dB
Design level (UL) N=M+L dB
Uplink enhancing
technologyO dB
The maximum uplink
path loss allowed
P=A+B+C+D-E+F-N dB
Choose the maximum path loss allowed for the link which is limited, that is, Min (P uplink, P downlink)as the maximum path loss allowed for the whole link!
Downlink Uplink
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 30/60
19. How to avoid the unbalanced link in network
planning?
The maximum uplink path loss allowed < The maximum downlink path
loss allowed, difference value > 2dBUplink limited Increase the
uplink coverage or decrease the invalid downlink coverage Link
balance
Solution: Add TMA, adopt 4 antennae to do the diversity reception, lower
the transmission power of the carrier frequency and so on.
The maximum downlink path loss allowed < The maximum uplink
path loss allowed, difference value > 2dB Downlink limited
Increase the downlink coverage Link balance
Solution: Increase the transmission power of the set-top unit of BTS,
increase the number of antenna and feeder, DPCT technology, DDT
technology and so on.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 31/60
1. What is propagation model?
2. What are the categories of propagation model?
3. What are the frequently-used propagation
models?
4. Why is propagation model calibration necessary?
5. How to evaluate whether a propagation model is
suitable or not?
6. How to get a propagation model before the
calibration is done?
3. Propagation model
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 32/60
1. What is propagation model?
A propagation model is a kind of mathematical model which
describes and reflects the features of the transmission
environment of the radio signals and the rules for the
changes of the signals. Actually, a propagation model
represents a typical model of the transmission environment
which has some specific features.At the planning stage, the propagation model can be used in
the following two ways.
Estimation of thecell radius
Simulation
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 33/60
2. What are the categories of propagation model?Model Statistical model Deterministic model
Concept The propagationmodel is based on
the statistical
analysis of a large
quantity of testing
data.
The propagation modelis obtained through the
simulation of the multi-
path transmission
traces of the radio
waves. The simulation
is based on the
geometrical information
of the clutter and the
buildings which appear
on the transmission
path.
Amount of calculation Small Large
Computational accuracy Average Excellent
Requirements for theaccuracy of the digital map
20m~50m 1m~5m
The requirements for the
clutter of the digital map
The information of
the buildings is not
included.
The information of the
buildings must be
included.
Application range >1km <1km
Frequently-used models OKUMURA-HATA
COST231
VOLCANO
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 34/60
The frequently-used
propagation models
Okumura-Hata
Universal model
Volcano COST231
3. What are the frequently-used propagation models?
•0.5G~1.5GHz(For 900M) •Macro cell model•It is suitable for 900M sites wherethe simulation and scale estimationwill be done for a large quantity of sites in a wide range.
•1.5G~2GHz (For 1800M)•Macro cell model•It is suitable for 1800M sites wherethe simulation andscale estimation willbe done for a largequantity of sites in awide range.
•0.5G~2GHz (For 900/ 1800M)•Macro cell model•It is suitable for the sites where thesimulation and scale estimation will bedone for a large quantity of sites in a widerange.•At present, this model is adopted byAIRCOM/CNP.
•0.5G~2GHz•Micro cell model•It is suitable for aspecific area where thesimulation will be donefor a small quantity of sites.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 35/60
4. Why is propagation model calibration necessary?
The radio transmission environment differs for each place due to the various land
forms, geographic features, distribution of buildings, coverage of vegetation, and so
on. For example, cities in plain areas VS cities in areas with hills, cities where there is
a dense distribution of high buildings VS cities where most of the buildings have 1~2
storeys, cites in desert areas VS cities in areas where there is a wide coverage of
vegetation … … Actually, propagation model calibration is necessary for each city.
The purpose is to get the parameters of the propagation model which is consistent
with the actual situation.
If the same set of parameters is applied to every scenario, it is quite possible that the
planning scheme differs greatly from the actual situation. Here are the consequences:
1. The network coverage which has been established is not good enough to meet the
coverage KPI.2. It is a large waste of resources if there are too many sites. Besides, severe
interferences may appear if there is a dense distribution of sites.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 36/60
5. How to evaluate whether a propagation model is
suitable or not?
Before the calibration:
The Mean Error is not 0, the standard deviationStd Dev is large.Figure: The intersection point of the red line andthe vertical axis is not 0.0; the slope of the redline is not 0.
Horizontal ordinate: The logarithm of the distance betweenthe testing place and the base station is represented bylogd.Vertical ordinate: The Mean Error which is calculated bycomparing the actual level of the testing place and thepredicted level of that place is represented by Error.Dense dots: Testing placesThe red line: It shows a kind of tendency about what the Mean Error is likely to be when the overall actual testingvalues of the testing place are compared with thepredicted values.
After the calibration:The Mean Error tends to be 0, the standarddeviation Std Dev<=8dB. This means the model isquite consistent with the actual situation.(For dense urban areas, std dev<=10dB is alsoacceptable. );Figure: The intersection point of the red line andthe vertical axis is 0.0; the slope of the red line is 0.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 37/60
6. How to get a propagation model before the calibration
is done?
Conditions
1. The digital map of the city for
which the planning will be done.
2. In the propagation model library,
there are a certain amount of
parameter sets related to the
propagation models, which are
reliable and accurate.
3. A tool used for choosing a model
automatically
If it is not possible to carry out the propagation model test or calibration of the
target city due to the problems of resources or time and the like, it is acceptableto choose a propagation model from the model library by following some certain
rules. This model can be regarded as an alternative choice, which should be
similar to the actual radio environment of the target city. However, there may be
some differences between the alternative choice and the actual situation.
As to the rules for choosing the model, they can be set up according to the
experience of the engineers or by using some customized automatic tool.Actually, this kind of tool will be applied to the Road Map of CNP.
Risks
It should be noticed that the model,
which is selected by using the tool, can
only be regarded as the most suitablemodel from the existing model library.
However, it does not mean that it is
completely matched with the actual
environment.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 38/60
1. How to estimate the coverage radius of a
single site?
2. What’s the influence of downtilt over the
coverage?
3. How to calculate the site distance at the pre-
planning stage?
4. How to estimate the coverage area of a singlesite?
5. How to estimate the scale of coverage?
4. Estimation of the coverage scale
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 39/60
1. How to estimate the coverage radius of a single site?
Choose a universal propagation model:PL=k1+k2*lgd+k3*Hm+k4*lgHm+k5*lgHb+k6*lgHb*Lgd+k7*diffraction+ clutter LossHere,PL means the maximum path loss allowed for the whole link, which is calculated in the link budget.k1~k7 and Clutter Loss are the parameters which are obtained after the propagation modelcalibration. (As to the estimation of the radius, only k1 ~ k6 will be involved in the calculation.)
Hm is the height of MS.Hb is the effective height of BTS antenna.d refers to the distance between the base station and MS (km).When d of the model above is calculated in a reverse way, the following formula can be obtained.d=10^((PL-K1-K3*Hm-k4*lgHm-k5*lgHb)/(k2+k6*lgHb))Here d is actually the estimated coverage radius R of the base station.
Link budget Get the maximum path loss allowed for a whole link, that is, PL.1
Propagation model calibration Get the value of each parameter of the propagation model2
Calculate “d” of the propagation model formula in a reverse way Get the maximumcoverageradius of the site
3
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 40/60
2. What’s the influence of downtilt over the coverage?
When the maximum path loss allowed is calculated in the link budget, the influence
exerted by the downtilt is not taken into consideration. If the influence exerted by thedowntilt over the coverage is to be taken into consideration, the radius should be
estimated according to the following formula.
DT: Downtilt (mechanical downtilt +electrical downtilt)H: The antenna height of BTSAtan:Inverse tangent trigonometric
functionVB: Vertical 3dB beamwidth of theantennaDF: The distance to the farthest placewhich the upward 3dB beamwidth cancover. It is the predicted coverage radiuswhen the downtilt DT is taken intoconsideration.DN: The distance to the nearest placewhich the downward 3dB beamwidth cancover D: The distance covered by the main loberight ahead
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 41/60
3. How to calculate the site distance at the pre-planning
stage?
Three-sector
directional sites Omni sites
The distance between two three-
sector directional sites is 1.5R.R represents the radius of the
directional cell.
The distance between two omni
sites is 1.73R.R represents the radius of the
omni cell.
If two-sector directional sites are used for the
coverage of a long and narrow road, the distance
between the sites should be 2R.
R represents the radius of the directional cell.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 42/60
4. How to estimate the coverage area of a single site?
A three-sector
directional siteAn omni site
Cell radius R
The coverage area
of a single cell0.65R2 2.6R2
The coverage area
of a single site1.95R2 2.6R2
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 43/60
5. How to estimate the scale of coverage?
MU
SU
For example,
According to the radio environment, the target city A
is divided into two parts, that is, the mean urban areaMU and the suburban area SU. The two areas are
represented by two polygons separately.
MU SU Notes
Cell radius km 0.5 1 R The estimated
radius R
The size of the coverage
area of a single cell km2 0.1625 0.65 0.65R2
The size of the coverage
area of a single site km2 0.4875 1.95 1.95R2
The size of the polygon
km2 4 10The size of the
polygon S
The number of BTSs(Num) 8 5 Num=S/(1.95R2)
The total number of
BTSs of the city A 13 =Num(MU)+Num(SU)
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 44/60
1. How many coverage enhancing technologies are
there?
2. What is bypass?
3. What is DPCT?
4. What is DDT?
5. What is FWDR?
6. What is IRC?
5. Coverage enhancing technologies
1 H h i h l i
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 45/60
1. How many coverage enhancing technologies are
there?
Uplink coverage
enhancing
Downlink
coverage
enhancing
Notes
TMA Bypass
DPCT and DDT can
not be used at the
same time.FWDR DPCT
IRC DDT
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 46/60
2. What is bypass?
Combiner
Duplexer
LNA
CDU
TX1 TX2 ETX
RX1
RX2
RX3
RX4
ERX
1
ERX
2
Combiner
Duplexer
LNA
CDU
ANT(RX/TX)
TX1 TX2 ETX
RX1
RX2
RX3
RX4
ERX
1
ERX
2
TRX1 TRX2
ANT(RX/TX)
TX RXM RXD TX RXM RXD
If a cell is configured with no more than 2 carrier frequencies, the TX interface of a carrier frequency
can be connected to the ETX interface of a CDU, then, it can be connected to a Duplexer directlywithout the use of a combiner.
When the link budget is calculated, only 1dB duplexer loss is considered, and the power of the set-
top unit is increased.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 47/60
3. What is DPCT?
Dual Power Combining Transmission
DPCT means that two transmitters send the same bursts at the same time,
which are combined in the form of one carrier frequency through a
combiner so as to increase the output power.
From a physical perspective, DPCT can help to increase the power, so it is
especially suitable for areas which need a wide coverage.
The two signals have the same phase
and amplitude, and they are combined
within a carrier frequency module.
Theoretically speaking, 3dB downlink
gain can be obtained if one PA is
combined with another. However, if the
internal loss is taken into consideration,
the actual gain of DPCT is 2.5dB.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 48/60
4. What is DDT?
Delay Diversity Transmission
DDT means that two carrier frequencies send the same signals at a slightly different
time. The signals are sent out by different antennae so as to get some time/space
diversity gain. In this way, the downlink coverage is enhanced. DDT is suitable for
some complicated radio transmission environment.
At BSC side, the main/auxiliary TRX can be regarded as one TRX, and the
parameters which the auxiliary TRX is configured with are the same as those whichthe main TRX is configured with. The quantity of signs inserted between them can be
configured at OMCR.
The downlink gain which can be generated by DDT is 2~3dB.
RF PA
RF PA
Phase adiust
algorithm
Phase adiust
algorithm
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 49/60
5. What is FWDR?
Four Way Diversity Receiving
FWDR means that 4 single antennae or 2 dual-polarized antennae are
used to make a single carrier frequency have four-way received signals.
Then, these signals are combined as a one-way signal through the
merging algorithm so as to enhance the diversity gain.
Compared to the two way diversity gain, FWDR can generate an extra 2~3dB gain for the uplink receiver sensitivity. Under the multi-path loss
condition, the dense urban areas which have a complicated transmission
environment can have a higher gain.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 50/60
6. What is IRC?
IRC: Interference Rejection Combining
If the interferences of the diversity reception signals from two different ways are
relevant to each other, the relevance computing will be done for the noises of each
diversity branch to check the relevancy between the interferences and to combine the
signals accordingly. The purpose is to complete the interference rejection and to
improve the quality of the received uplink signals.
With IRC, C/I can get about 3~5dB gain in dense urban areas where the radio
environment is complicated.
MRC: Maximum Ratio Combining
If the interferences of the diversity reception signals on two different ways are not
relevant to each other, weighting and combining should be done to the signals from M
different ways.
If the interferences received from different antennae are notrelevant to each other, the performance of IRC is similar tothat of MRC. However, if the interferences are relevant to each other,IRC is much more stronger than MRC in terms of the interferencerejection ability.
6 Th f tl k d ti b t
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 51/60
1. What is a blind zone under a tower?
2. How to solve the problem if there is a blind zoneunder the tower?
3. What is weak coverage?
4. How to solve the problem of weak coverage?
5. What is overshooting?
6. How to solve the overshooting problem?
7. When is it called that there is not a serving cell?
8. What measures can be taken to solve the problem
that there is not a serving cell?
6. The frequently asked questions about
coverage planning Q&A
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 52/60
1. What is a blind zone under a tower?
Null: It refers to the deep fading point between thecentral lobe and the side lobe, or between two sidelobes.
-70dBm
-90dBm
-80dBm
-90dBm
A blind zone under a tower refers to a part of the user zone which needs to becovered, an area which is covered by the first null or the second null under the
vertical antenna radiation pattern. Compared to any other area which is either near or far, the signal strength of the blind zone under a tower may havegreater attenuation (20~30dB), and a weak coverage area is formed. As aresult, there may be a large number of subscriber complaints, and the KPIs of call drop rate and the like may be affected. The location of the blind zone under a tower is related to the antenna radiationpattern, the antenna height, and the transmission environment.
A blind zoneunder a tower
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 53/60
2. How to solve the problem if there is a blind zone
under the tower?
Null fill: The shaped-beam should be used to complete the first lower null fill of
the side lobe of the vertical pattern of the antenna so as to reduce the deepfading of the null.
Choose a null fill antenna;Choose an electrical downtilt antenna;Adjust the antenna downtilt appropriately so as to avoidthe blind zone under a tower in a dense user zone.
An antenna with a null fill An antenna without a null fill
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 54/60
3. What is weak coverage?
Weak coverage means that the signal level is too low to keep a
good call quality. It is usually believed that the coverage will beweak if the signal level is lower than -90dBm. If the coverage isweak, there will be many problems, for example, subscriber complaints, high call drop rate, and so on.
For example, the power of the set-top unit of the base
station is too small; the site planning is not reasonable;
the antenna height is too low according to its original
design; the inclination is too large; there is some
blocking because of the land forms or the buildings.
Concept
Causes
A weak coverage
area
A weak coverage
area
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 55/60
4. How to solve the problem of weak coverage?
At the network planning stage, more attention will be given tothe possible weak coverage areas. The following factors
should be taken into full consideration: The site location, the
antenna type, and the reasonableness of the designed
engineering parameters.
Increase the power of the set-top unit of the base station.
Check the decreased power problems caused by theequipment failures.
In the weak coverage areas, some base stations or repeaters
should be added.
?
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 56/60
5. What is overshooting?
Overshooting means that the actual coverage range of a
cell exceeds the range which has been designed
beforehand and an overlapping area is formed by this celland another cell which is far from it.
Overshooting may result in frequent handovers, an
increase of interferences, the islanding effects, and so on.
Here are the possible causes: The transmission power
of the base station is too large; the antenna lobe is toolarge; the antenna is too high; the inclination is too
small; there is an uneven land form; and so on.
Concept
Causes
A
B
C
Cell A is anovershooting
area.
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 57/60
6. How to solve the overshooting problem?One should be cautious when the site location is selected for a
highland or a mountain slope.
It should be ensured that the antenna type and the engineering
parameters of the antenna should be reasonably selected or designed
at the network planning stage.
The coverage area of the overshooting area should be controlled
through the adjustment of engineering parameters and the
transmission power of the base station.
If it is not possible to control the coverage at that time, it is suggested
that some neighbor cells should be added to the overshooting cell.
A
B
C
Enhance the neighbor cellrelations between A and C.
A
B
C
Control the coverage area of A.
7 Wh i it ll d th t th i t i ll?
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 58/60
There are frequent cell reselections when the handset is at an idle state.
In the cells at the borders of LAC, the location update occurs frequently due to the
frequent cell reselections. As a result, there will be an unnecessary increase of signalingload or congestion. Besides, there will be “ping-pong handovers” during the calls, and
the voice quality will deteriorate.
The transmission rate of the data service will be affected.
Because of the fluctuations of signals, there will be more subscriber complaints.
There are interferences, C/I is not satisfactory, and the voice quality deteriorates.
7. When is it called that there is not a serving cell?
For 2 or more cells, the signal strength of one cell is quite close to that of another cell, it is not
found that the signal strength of any cell has a big advantage over other cells. The handset has
frequent cell reselections when it is at an idle state, or there are “ping-pong handovers” during
the calls. The problems mentioned here are caused by the fact that there is not a serving cell.
The engineering parameters of the antenna are not designed in a
reasonable way.
The transmission power of the
carrier frequencies is too large or
too small.
The configuration of the
parameters is not reasonable ……
For the 3 cells in this area, thesignal level of each cell isalmost the same, so there isnot an obvious serving cell.
Concept
Influence
Causes
8 What measures can be taken to solve the problem
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 59/60
8. What measures can be taken to solve the problem
that there is not a serving cell? Adjust the antenna directional angle or the antenna
downtilt so as to ensure that there is a serving cell of
the coverage area, which has relatively strong and
stable signals.
Adjust the transmission power of the carrier
frequencies of the relevant cells so as to ensure that
there is a serving cell of the coverage area, which has
relatively strong and stable signals.
When the serving cell of the area is made clear, it is
suggested that the cell reselection parameters should
be adjusted so as to ensure that the subscribers can
reside in the serving cell as long as possible. In this
way, it is possible to relieve the frequent cell
reselections.
When the serving cell of the area is made clear, it is
suggested that the handover parameters of the cells should
be adjusted so as to reduce or eliminate the “ping-pong
handovers” during the calls.
1
2
3
4
7/28/2019 GO NP04 E1 1 GSM Coverage Planning-60(New)
http://slidepdf.com/reader/full/go-np04-e1-1-gsm-coverage-planning-60new 60/60
top related