lte radio dimensioning

Soc Classification level 1 © Nokia Siemens Networks

LTE Radio Dimensioning

Tuesday, 03.04.2008, 16:30 - 18:00 Finish time

Presenter: Tomas Novosad MS/Dallas

Soc Classification level Presentation / Author / Date 2 © Nokia Siemens Networks

Contact information / download location

• If you have any questions, please contact presenter:

Tomas Novosad

[email protected]

phone: +1 469 855 0738

MS Dallas

• Slides will be available in IMS/Sharenet

• References: material from Dr. Harri Holma, NSN COO RA RD SA NE, and Dr. Carlsten Ball


LTE Radio Dimensioning

• LTE Radio Interface specifics

• Comparison of LTE radio interface against UMTS and WIMAX

• LTE Power Budget – what is new?

• Radio Dimensioning & tool info

• LTE Performance examples


Main LTE Features/Targets

Packet switched optimized

Peak rates uplink/downlink 50/100 Mbps

Enables round trip time <10 ms

Ensure good level of mobility and security

Improve terminal power efficiency

Frequency flexibility with 1.4, 3, 5, 10, 15 and 20 MHz allocations

Capacity 2-4 times higher than with Release 6 HSPA


LTE/SAE Overview

Two mandatory Network Elements: eNB and aGWFocus is on enhancement of Packet Switched technology

high data rates, low latency, packet optimised flat IP system

Comprehensive Security

Mobility Concept with tight Integration for 3GPP accesses

Streamlined SAE Bearer Model with Network Centric QoS Handling

On/Offline & Flow Based Charging

Core NetworkRadio Network

eNode

B

Access

Gateway

(aGW)

HSS/AAA

Core Control

PCR

F

PCRF: Policy and Charging Control Function

aGW: Access Gateway

IMS


Key Radio features of LTEMany similarities with HSPA/HSPA+….

Fast Link Adaptatio

ndue to

channel bahaviou

r

Short TTI = 1 ms

Transmission time interval

AdvancedScheduling

Time & Freq.

TX RX

Tx RxMIMO

Channel

DL: OFDMA

UL: SC-FDMA

scalable

Up to 64QAMModulation

ARQ

Automatic Repeat Request

Frequency re-use 1


Scalable & spectrum efficient air interface

•Lower peak-to-average power ratio: improved power-amplifier efficiency, low cost terminals with long battery life, good coverage

•Localized allocation for frequency domain scheduling and interference co-ordination/ avoidance (not possible with WCDMA)

•Orthogonal transmission from multiple users: reduced eNB complexity

Uplink:

SC-FDMA

•Orthogonal sub-carriers: improved spectral efficiency and simple UE processing

•Frequency domain scheduling and interference co-ordination/avoidance (not possible with WCDMA)

•Better suited for MIMO than WCDMA

Downlink:

OFDMA

* At 20 MHz bandwidth, FDD, 2 Tx, 2 Rx, DL MIMO, PHY layer gross bit rate ** roundtrip ping delay (server near RAN)


Frequency Domain Scheduling

Frequency

Resource block

Transmit on those resource blocks that are not faded

Carrier bandwidth

• Frequency domain scheduling uses those resource blocks that are not faded

• Not possible in CDMA based system


Gain of Frequency Domain Scheduling

• Cell throughput gain can ideally exceed 40% with at least 5 simultaneous users

• System simulations show a gain up to 30-40%

1 32 4 6 7 95 8 100

10

20

30

40

50

60

Max. no. of users per sub-frame [-]

FDP

S ga

in o

ver

ref.

(D+P

F) [%

]

Cell capacity

User data rate (5% outage)


Performance Numbers Peak Data Rates Peak data rates

0

10

20

30

40

50

60

70

80

90

100

2 x 5 MHz 2 x 5 MHz 1 x 10 MHz 1 x 20 MHz 2 x 10 MHz 2 x 20 MHz

HSPARelease 6

HSPARelease 8

WiMAX802.16e

WiMAX802.16e

LTERelease 8

LTERelease 8

Mbps

DownlinkUplink

• Rather similar Peak Data Rates for HSPA evolution and WiMAX

• LTE provides outstanding Data Rates beyond 150 Mbps in 2 x 20 MHz Bandwidth due to less overhead

• WiMAX uses asymmetric 29:18 TDD in 10/20 MHz, whereas HSPA and LTE use FDD with 2 x 5 and 2 x 10/20 MHz

• Prerequisite: 2x2 MIMO with 64-QAM in Downlink

> 150 Mbps


Performance Numbers Mobile Technology Capability Limits

Theoretical peak bit rate in ideal case DL/UL 80 / 16 Mbps

WiMAX TDD 20 MHz

42 / 11 Mbps

HSPA R7 (HSPA+)

Latency (round trip) 30 ms30 ms

Spectral efficiency data DL/UL [bps/Hz/cell] 1.5 / 0.61.4 / 0.6

160 / 50 Mbps

LTE R8 FDD 2x20 MHz

10 ms

2.1 / 0.9

14 / 5 Mbps

WCDMA HSPA R6

50 ms

0.7 / 0.4

Max path loss 1 Mbps / 64 kbps 153 dB162 dB 162 dB162 dB

Spectrum 2300, 2500, 3500IMT-2000 bands

Spectral efficiency voice [users/MHz/cell] 1830 45551823

Cell range in urban area (indoor – outdoor)

IMT-2000 bands IMT-2000 bands

54 Mbps 260Mbps

WLAN 802.11g/n

<5 ms

<0.51.0

110 dB

12

2400, 5400

30100 m2.87.4 km 0.61.5 km2.87.4 km 2.87.4 km

All radio standards show comparable performance under comparable conditions and similar feature set:

• Laws of physics apply to all of them

• User rates mainly depend on bandwidth, modulation/coding and availability of MIMO (2x2 assumed)

• Spectrum Efficiency is determined by Frequency Reuse and Feature Set (e.g. FSPS, MIMO, …)

• Latency (e.g. PING Performance) depends on chosen Frame Duration or TTI

• Coverage depends on frequency band, RF power limitations and duplex mode


Frequency Reuse One in LTE

• LTE is designed for frequency reuse of one no frequency planning required

• Inter-site interference coordination is possible by exchanging load information over X2 interface = soft frequency reuse

• Current simulations show no clear performance gains in downlink from inter-site interference coordination

• Some performance potential in uplink by exchanging overload indicator information

X2

X2


LTE Frequency Variants in 3GPP – FDD

1

2

3

4

5

7

8

9

6

2x25

2x75

2x60

2x60

2x70

2x45

2x35

2x35

2x10

824-849

1710-1785

1850-1910

1920-1980

2500-2570

1710-1755

880-915

1749.9-1784.9

830-840

Total [MHz]Uplink [MHz]

869-894

1805-1880

1930-1990

2110-2170

2620-2690

2110-2155

925-960

1844.9-1879.9

875-885

Downlink [MHz]

10 2x60 1710-1770 2110-2170

11 2x25 1427.9-1452.91475.9-1500.9

1800

2600

900

US AWS

UMTS core

US PCS

US 850

Japan 800

Japan 1700

Japan 1500

Extended AWS

Europe Japan Americas

788-798 758-768

777-787 746-756

UHF (TV)

US700

2x10

2x1013

12 2x18 698-716 728-746

14

790-820 832-862?2x30?xx

US700

US700


Wimax & LTE, 3G and HSPA

FEATURES AND TECHNIQUES

Wimax/LTE 3G HSPA

Frequency reuse 4-1(WiMAX) 1 (LTE) 1 1

Terminal antenna Omni or directional Omni Omni

Channel impairment Sensitive to doppler Sensitive to multipath

Sensitive to multipath

Base station antenna Directional, array Directional Directional

Main radio KPI SINR EcNo EcNo (SINR)

Dominant Traffic Data Voice Data

Handover Scheme HHO SHO HHO (HSDPA)SHO (HSUPA)

Own-cell Interference Adjacent subcarriers at high doppler

Other codes in the cell, non-orthogonality issues

Other codes in the cell, non-orthogonality issues

Capacity Expansion Increasing the OFDMA bandwidth or more carriers

More carriers using Inter-frequency Handover

More carriers

Detail comparison LTE-WiMAX is on the Appendix slides


LTE Power Budget

Based on NSN COO RA RD SA NE 2 material


Where to find the LTE Power Budget?

•LTE Power budget is provided by NSN COO Network Engineering

•IMS link for current version

•https://sharenet-ims.inside.nokiasiemensnetworks.com/livelink/livelink?func=ll&objId=375035353&objAction=Browse&viewType=1

•The budget should be accessible later via Network Planning IMS


Target of the Link Budget calcuation

• Estimate the maximum allowed path loss on radio path from transmit antenna to receive antenna

• Reach the specific radio and service conditions i.e.:– User Service Throughput

– BER/BLER (SINR) requirements

– location probability settings

– Required penetration loss

• Calculate maximum cell range for estimated PathLoss PahtLossmax_DL

PathLossmax_UL

R


LTE Link Budget – Tool structure• Tool is composed of five excel sheets

– Instructions General tool info User’s guide

– Link Budget main part of the tool, all input parameters and outputs are generated in

this section

– Graphs Plots of Interference Margin in a function of neighbour cell load for UL

and DL for specified parameters • User Service Throughput• Neighbour Cell Load• Chosen Modulation and Coding Scheme

– Calculations Internal calculation data and constants are stored in this section – user

mustn’t interfere in stored data

– Doc History Information about released versions


LTE Link Budget – performance


LTE Link Budget – Resource and power allocation• Power Allocation

– Downlink Power per subcarrier is constant Maximum eNB transmission power is allocated on the whole available bandwidth i.e. in a 10 MHz power there are 50 RBs in frequency domain available

and transmission power will always be equally distributed on all 50 RBs – Uplink

Maximum UE Transmission power is allocated on RBs allocated to the user.– Subchannelisation gain in Uplink:

User can get lower than Max number of RBs in frequency domain to obtain link balance: Receiver Sensitivity decrease Transmission bandwidth decrease user throughput decreases UL cell range increases

• Resource Allocation (theoretical)– In two domains: time and frequency– Channel dependant scheduling

scheduler assigns resources on which a given user perceives good propagation conditions

very beneficial at low speeds (channel variations in time domain are slow)

scheduling done per subframe (1 ms) sheduling done wit RB granularity In UL allocated resources must be continuous in

frequency domain higher implementation complexity


LTE Link Budget – Resource and power allocation• Resource allocation (dimensioning example)

– Assumptions: On this example – on the figure: 1.4 MHz bandwidth i.e. 6 RBs in frequency domain (but 25 RBs for 5MHz) Resource Block capacity is estimated for a given MCS Service Throughput is specified

– Calculation algorithm: Firstly resources in time domain are allocated (assuming single resource block in frequency domain)

If there are not enough resources in time domain of single resource block, another resource block in frequency domain is allocated to the user

12*))1(*1000/*)0005,0/1(

(.OverheaedBLERRBCapacity

uterThroughpCellEdgeUsuproundNoOfRBUser


LTE LB – Capacity SectionUser Throughput & Overhead Approach• The approach was created to easily and in a convenient way estimate cell

range for a given service or cell edge criteria– User has to type in Service Throughput only– The tool calculates minimum bandwidth which is needed for a given service (No. of RBs

needed per one user)– all overheads are can be calculated automatically

• User is able to set the criterion for cell edge*:– Max Coverage– Max Cell Capacity– Service Throughput

*Only for UL; In DL power per subcarrier is constant


LTE LB – Capacity SectionGeneral Settings• Cyclic prefix

– Prevents from inter-symbol interferences Normal – 7 OFDM symbols per slot for

data transmission Extended – 6 OFDM symbols per slot for

data transmission (large cells or MBMS)

• Resource block capacity– Depends on used MCS

– RBCapacity (bit) = M * Coding * 7(6) * 12 (M – Modulation Density, 7 (6) – seven or six OFDM symbols, 12 – number of subcarrier per PRB)

• Number of Resource Blocks per second– Depends on chosen Channel Bandwidth

– RBSecond = MaxRB/0,0005(MaxRB – maximum number of RBs in frequency domain; 0,0005(s) – time interval of a subframe

• Throughput per subchannel (kbps)– Throughput of one resource block in frequency domain over one second for a chosen MCS

• Maximum MCS Throughput– MCSThroughput = RBCapacity*RBSecond*(1-BLER-Overheads)/1000

– Depends on: chosen MCS channel bandwidth Cyclic Prefix option Overheads


LTE Link Budget – Receiver Sensitivity & SINR• Receiver sensitivity

– gives an indication of receivers ability for detection of low level signals– is a function of:

Signal to Interference and Noise Ratio Receiver’s Noise Figure Channel bandwidth

– RxSensitivity (dBm) = PNoise (dBm) + SINR (dB) + NF (dB) + 10* log (NoOfRB*12)where: PNoise (dBm) = 10 log ( k T B) + 30 = - 132.24 (dBm) (=Noise Power per subcarrier) NF – Receiver’s Noise FIgure NoOfRB – Number of Resource Blocks used for transmission

Note! In Uplink this is Number of Resource Blocks assigned for user transmission, in Downlink this is maximum number of Resource Blocks for a chosen bandwidth.

• SINR (based on link level simulations)– defines what should be the minimum relation between useful signal (meaningful inforamation)

and sum of interferences coming from own and neighboring cells and the received noise power– Depends on:

Modulation and coding scheme Antenna configuration (SISO, MIMO, Rx Diversity) Channel bandwidth and channel type (currently AWGN only values are implemented)


LTE Link Budget – Interference MarginDownlink


LTE Link Budget – Interference MarginUplink

• Uplink Interference Margin– Currently obtained from system level simulations

– Is a function of cell load


LTE Link Budget – Maximum Allowable Pathloss

• Maximum Allowable Pathloss Calculation:– MAPL formula expresses the

maximum allowable attenuation of the radio wave traversing air interface

– Together with propagation model it is used for cell range estimation

– The formula is the same for UL and downlink

ShadowingnLossPenetratioBodyLossceMArginInterferen

RxGssRxFeederLoityRxSensitivEIRPsMaxPathlos Ant

Soc Classification level 28 © Nokia Siemens Networks

Network Dimensioning based on Dim Tool v 0.3 AFIAir Interface Dimensioning

Based on NSN COO RA RD SA NE 2 material


LTE Dimensioning

GeneralParameters

EquipmentParameters

Maximum Path Loss

Cell Range

Cell Area, Site to Site Distance

RadioPropagationParameters

RadioPropagationPrediction

RadioNetwork

Conf.

UserService

Characteristics


Where to find the LTE Dim Tool?

•Tool is provided by COO Network Engineering

•IMS link for current version (DRAFT)

•https://sharenet-ims.inside.nokiasiemensnetworks.com/livelink/livelink?func=ll&objId=375039115&objAction=Browse&viewType=1

•The tool should be accessible later via Network Planning IMS


LTE Dim Tool – Tool structure• Tool is composed of six excel sheets

– Instructions General tool info User’s guide

– Link Budget the same functionality and GUI as in Link Budget tool, the inputs of this

section are used also for capacity dimensioning Link Level (LL) results provided by COO RA RD

– Capacity Sector throughput estimation Based on System Level results provided by COO RTP

– Network Dim Site count with respect to coverage, capacity and traffic dimensioning

– Calculations Internal calculation data and constants are stored in this section – user

mustn’t interfere in stored data– Doc History

Information about released versions


LTE Dim Tool - dimensioning process

Link Budget Capacity dimensioning

Input parameters Outputs

User Interface

Network dimensioning

Traffic dimensioning

- Calculation

- Inputs/Outputs

• Operating band• Transmitter/receiver parameters• etc.

• LL results• SINR distribution• Antenna Conf.• etc.

• Areas• No. of Subscribers• Phases•etc.

• Maximum Pahtloss• Cell ranges• etc.

• UL/DL Max sector throughputs

• MCS Maximum Throughput• UL/DL Pathloss • Cell Load

• MCS• Target User Throughput• etc.


LTE Dim Tool – Capacity Dimensioning section• Capacity Dimensioning provides Maximum Sector Throughput values per

scenarios defined in 3GPP TR 25.814– DL based on LL results

for chosen antenna and SINR distribution

– for UL two methods available Max Pathloss MCS distribution User can choose appropriate method in Network Dimensioning tab.

• Sector Throughputs are calculated with respect to Neighbor Cell Load defined by user and used also for Interference Margin calculations

• All inputs for Capacity Dimensioning are defined in LB module– mainly in capacity section

• To recalculate scenario user has only to push one button


LTE Dim Tool – Capacity Dimensioning Principle

• Current Dimensioning based on MCS Distribution– Cell Throughput is calculated on basis of area covered by each

available MCS

• Alternative possibility is to replace the calculated results by simulation results/estimations or by throughput-SINR curves.


SINR distribution provided by COO RTP

Simulation environment is described in "LTE Downlink Performance Results with Time-Domain Scheduling - Using UPRISE" by Klaus I Pedersen et al.


LTE Dim Tool – Capacity DimensioningDownlink

– DL MAX Throughput values are multiplied by SINR Distribution and summarized

– In last step the obtained sum is multiplied by Neighbor Cell Load factor which scale the final result – Sector Throughput

Σ

X =

X

SINR Histogram


LTE Dim Tool – Capacity DimensioningUplink – UL MCS distribution

• Dimensioning based on UL MCS Distribution– Calculation steps:

Main parameters have to be set: Cell Edge User Throughput, Neighbor Cell Load, Maximum MCS Throughput)

For each MCS the corresponding Site Area is read and written into the table

Area covered by each MCS is calculated (e.g. For QPSK 1/6:MCS_Area = QPSK_1/6_Site Area - QPSK _1/3_Site Area)

MCS Area is divided by total Site Area (Site Area of lowest MCS) which gives MCS distribution factor

Max MCS Throughputs are multiplied by MCS Distribution factor and summarized

In last step the obtained sum is multiplied by Neighbour Cell Load factor which operation gives the final result – Sector Throughput

Σ

X =


• Network Dimensioning module provides site count for defined scenarios• Network dimensioning module parameters:

– phase selection ( currently four but it’s a minimal effort to extend number of phases)– traffic requirements:

Population Penetration rate Number of Subscribers

Subscription rate• Total throughput of all users’

service subscriptions Overbooking factor

• gives an indication how muchbandwidth can be overbooked by network operator (e.g. for 1 Mb bandwidth and overbooking factor of 10, the operator can sell services with total throughput of 10 Mb)

Total peak traffic

LTE Dim Tool – Network dimensioning

nRatePenetratio*PopulationsSubscriber

gOverbookin

onRateSubscripti*sSubscriberalTrafficTot


Dimensioning results – sites per cov & capSite Capacity (kb/s)

Macro Case 1 Macro Case 3 Micro Outdoor Micro IndoorUplink Capacity based on DL Pathloss NO NO YES YES

Downlink 16,003 14,956 8,069 8,192Uplink 10,512 11,656 5,228 5,308

Site Area (square km)Macro Case 1 Macro Case 3 Micro Outdoor Micro Indoor

Downlink 2.49 2.36 0.375 0.083Uplink 2.26 2.08 0.356 0.078

Number of Sites - Capacity - DLMacro Case 1 64 154 269 410Macro Case 3 83 181 307 461

Micro Outdoor-to-Outdoor 178 366 605 894Micro Outdoor-to-Indoor 200 390 630 920

Number of Sites - Capacity - ULMacro Case 1 49 117 205 312Macro Case 3 53 116 197 296


Number of Sites - Coverage - DLMacro Case 1 21 23 25 27Macro Case 3 34 39 43 47


Number of Sites - Coverage - ULMacro Case 1 23 25 27 29Macro Case 3 39 44 49 53


Number of SitesMacro Case 1 64 154 269 410Macro Case 3 83 181 307 461



Cell Ranges Examples, Outdoor, OH model


Different Technologies within same BW=5MHz

Cell Range for 384k-1M DL / 64k -500k UL

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

RAN04_DPCH 3

84k/

64k

RAS05_HSDPA 3

84k/6

4k

RAS06_HSPA 3

84k/6

4k

WiM

AX 1M

/128

k

LTE 1

M/50

0k

[km

]

DL

UL


Different technologies within maximum BW (UMTS=5MHz, WiMAX=10MHz, LTE=20MHz)

Cell Range for 384k-4M DL / 64k-2M UL

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

RAN04_DPCH 3

84k/

64k

RAS05_HSDPA 3

84k/6

4k

RAS06_HSPA 3

84k/6

4k

WiM

AX 2M

/256

k

LTE 4

M/2M

[km

]

DL

UL


Thank you for your attention


Appendix: Comparison WiMAX - LTE


WiMax 802.16e LTE Comments

Network ArchitectureFlat, IP based;BS + ASN GW

Very Flat, IP basedeNodeB + aGW

Both technologies with significantly reduced number of

nodes compared to 2G/3G.

Services Packet Data, VoIP Packet Data, VoIP

Mobility Mobile IP with targeted Mobility < 120 km/h

Full 3GPP Mobility with Target up to 350 km/h; 2G/3G Handover and

Global Roaming

LTE is fully embedded in the 3GPP world incl. interRAT HO.

Access technology Scalable OFDMA in UL & DL

DL: OFDMA, UL: SC-FDMA

SC-FDMA reduces PAPR by ~5 dB UL improvements !!!

Channel BW 1.25, 3.5, 5, 7, 8.75, 10, 14, 15, 20, 28 MHz

1.25, 2.5, 5, 10, 15, 20 MHz Both very flexible

FFT-Size and Subcarrier Spacing

128 – 2048; dF variable; 7- 20 kHz typically 10 kHz

128- 2048;fixed dF = 15 kHz

Large dF required againstDoppler => higher velocity

Cyclic Prefix Flexible 1 / 32, ….,1 / 4; CP required 1 / 8

Short (5 s) or Long CP (17 s)

Both designed to combat Multipath Fading in different

Environments

SpectrumLicensed & unlicensed,2.3, 2.5, 3.5 & 5.8 GHz

Licensed,IMT-2000 Bands

LTE available at preferred lowFrequency Bands Coverage

Advantage

Duplex ModeTDD + FDDTDD focus

FDD + TDDFDD focus

TDD requires Synchronization, FDD can be asynchronous.

Framing, TTI 2, …, 20 ms;5 ms required

fixed 2*0.5 ms slots = 1 ms sub-frames

TTI determines the Latency / PING

Modulation & Coding BPSK, …, 64-QAM;CC + CTC (+BTC+LDPC)

QPSK, …, 64-QAM; CC + CTC

LTE vs. WiMax Comparison (Radio Perspective 1)


WiMax LTE Comments

MIMO, # AntennasBS: 1, 2, 4 ; MS: 1, 2 Closed + open Loop

eNodeB: 1, 2, 4 ; UE: 2 Closed + open Loop

LTE working assumption is 2 DL Antennas per UE

MIMO Modes Diversity + Spatial Multi. Diversity + Spatial Multi.

HARQChase Comb. + IR;

stop & wait

Chase Comb. + IR; N=8 stop & wait;

UL Sync., DL Async.

Subchannel / Physical Resource Block

24 x 2 Constellation Points in PUSC Mode

12 x 14 Constellation Points

Interleaving / MappingAdjacent AMC 2x3 or

PUSC/FUSC Permutation;Focus Permutation

Localized + Distributed;Focus Localized

LTE prefers frequency selective Packet Scheduling,

WiMax focuses on interference averaging.

Pilot Assisted Channel Estimation (PACE)

DL Preamble + distributed permuted Pilots

depending on # Antennas

Distributed Pilots depending on #

Antennas

Overall Overhead @ MAC Layer

VoIP + Data Mixture typically ~ 25 %

VoIP + Data Mixture typically ~ 15-20 %

LTE is more efficient, e.g. VoIP optimizations

L1/L2 SignallingFlexible FCH + MAP

following the Preamble; Sync. by Ranging CH

Signaling Channels in max. first 3 Symbols;Separate BCH, SCH

LTE provides optimized and more efficient L1/L2-Signaling also utilizing CDM components

User MultiplexingFlexible arbitrary

Rectangles in T-F-DomainStripe-wise Allocation in

F-DomainLTE with less complex Ressource Signaling

LTE vs. WiMax Comparison (Radio Perspective 2)

lte radio dimensioning

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