Multi-Antenna System Performance and Impairments in Long Term Evolution Radio Access

268 Pages·2013·3.54 MB·English

by  Michel Chauvin

Multi-Antenna System Performance and Impairments in
Long Term Evolution Radio Access Networks using the
Extended Spatial Channel Model
by
MichelChauvin,B.Eng.
Athesissubmittedtothe
FacultyofGraduateandPostdoctoralAffairs
inpartialfulfillmentoftherequirementsforthedegreeof
MasterofAppliedScienceinElectricalandComputerEngineering
Ottawa-CarletonInstituteforElectricalandComputerEngineering(OCIECE)
DepartmentofSystemsandComputerEngineering
CarletonUniversity
Ottawa,Ontario
October,2013
(cid:2)cCopyright
MichelChauvin,2013
Abstract
Consumer demand for rich content delivered to portable wireless devices is pushing the
wireless industry and researchers to find ways to improve the efficiency of wireless net-
works. New technologies like LTE and LTE-Advanced are being refined and deployed to
meetdemands. Thisthesisstudiesthreeimportantareasofwirelesscommunicationsusing
LTE; phase noise, Doppler and link adaptation and the performance of various multiple
antenna systems. The thesis focuses on the performance of 4 base station antennas and
results obtained with the advanced 3rd Generation Partnership Project’s (3GPP) extended
spatial channel model (SCME). Simulations show the effect of each impairment and con-
figuration on the LTE physical downlink shared channel. The best performing antenna
configuration evaluated is the 4-transmitter, 4-port, correlated cross-polarized BS antenna
whenTM4’sclosed-loopspatialmultiplexingisused. Theresultsshowthata4antennaBS
setup provides gain over 2 BS antennas, despite the additional reference signal overhead,
due to the greater set of precoding matrices available with 4 antenna ports. When only
2 ports are available, TM3’s open-loop spatial multiplexing (OLSM) performs better than
TM4 as the user equipment (UE) becomes mobile, since 2-port TM3 is less dependent on
the channel state information. The practical implementation issues of link adaptation are
shown to cause a significant drop in throughput at medium and high UE velocities. The
resultsinthethesissuggestthatimprovingthelatencyofthelinkadaptationloopwithlow
complexity algorithms, or an increase in processing power, along with adaptive link adap-
tation reporting intervals can keep uplink overhead low and maintain a higher throughput
as velocity increases. The UE velocity is also pushed to extremes in the high speed train
on railway simulations and shows that LTE can operate with some throughput degradation
at 350 km/hr. Finally, the LTE downlink is also subjected to phase noise; an important
impairment present in communication systems employing up/down-conversion. The gen-
eratedphasenoiseandthemeasuredphasenoisesimulationsshowtheeffectofphasenoise
onthethroughput. Asexpected,therelativelyquietmeasuredphasenoisedoesnotsignifi-
cantlydegradetheLTEdownlink.
iii
Acknowledgments
I would like to thank my supervisor Prof. M. El-Tanany for his friendship and the genuine
guidance he provided when I would ask for his help. He unselfishly lent me his time for
any questions I had and occasional unrelated discussions about topics that interested us
both. He provided encouragement along the way and allowed me to explore additional
areas to satisfy my curiosity despite the extra time it would take to complete my thesis
work. I’m very grateful for the opportunity he gave me to learn a new field, work on an
interestingtopicandmeetanumberofwonderfulpeoplealongtheway.
I would also like thank my co-workers and mentors at Ericsson who often made
themselves available (at any time) to discuss projects on which we were working. They
inspired me since they had a tremendous amount of passion for the work they were
performing. Thank you to Edward, Ahmed, Guoqiang, Jianguo, Eliana, Xiaoming,
Alireza, Jianfeng and my cubicle neighbour, Sara, for the wonderful conversations and the
opportunity to learn and work with you. Thank you to Ericsson for supporting this thesis
workandgenerouslyallowingmetoworkontopicsofinterestandtheopportunitytowork
andconversewiththehighlyskilledpeopleintheSystemsteam.
Thereisnothingmoreimportantthanfamily andtheyaretheonesthatinspireyouand
nurture curiosity from a very young age. Thank you to my parents, Cathy and Richard,
who have helped me through challenging times and this most recent academic endeavor.
They have shown time and time again their support, shared their wisdom and I’m forever
gratefulfortheopportunitytoexploreanewfield. Tomywonderfulandsupportivefamily
Eric, Natalie, Michael and Kaitlin, Rolande, Lise and Tony, thank you for your endless
supportandencouragement.
To all the friends (Hamid, Wang, Hussein, Farouk, Rudhwan, Furkan, Xiao, Matthias,
Majid, Rania and many more) that I met in classes or elsewhere during our graduate
iv
studies,yourfriendshipmadethisanunforgettableexperience. Ihopethatyouwillallfind
work that you are passionate about as I truly believe you will all have a big impact on the
worldoneday.
v
Table of Contents
Abstract iii
Acknowledgments iv
TableofContents vi
ListofTables x
ListofFigures xiii
ListofSymbols xix
ListofAcronyms xxiii
1 Introduction 1
1.1 TheWirelessRadioAccessNetworks . . . . . . . . . . . . . . . . . . . . 2
1.2 LTERadioAirInterface . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 WirelessChannels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3.1 PathLoss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3.2 Fading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3.3 TransmitandReceiveDiversity: (MISO)and(SIMO)Channels . . 6
1.3.4 Multiple-InputMultiple-Output(MIMO)Channels . . . . . . . . . 6
1.3.5 SpatialChannelModels(SCM) . . . . . . . . . . . . . . . . . . . 8
1.4 LongTermEvolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.4.1 OrthogonalFrequencyDivisionMultiplexing(OFDM) . . . . . . . 8
1.4.2 LinkAdaptation . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.5 ThesisMotivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.6 Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
vi
1.7 ThesisContributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.8 OrganizationoftheThesis . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2 Background 14
2.1 WirelessFadingChannels . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.1.1 PathLossandShadowing . . . . . . . . . . . . . . . . . . . . . . 14
2.1.2 Multi-PathPropagationandSmall-ScaleFading . . . . . . . . . . . 15
2.1.3 FrequencyFlatandFrequencySelectiveChannels . . . . . . . . . 19
2.2 OrthogonalFrequencyDivisionMultiplexing(OFDM)Systems . . . . . . 22
2.2.1 OFDM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.2.2 CyclicPrefix(CP) . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.3 ChannelModeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.3.1 MotivationforChannelModels . . . . . . . . . . . . . . . . . . . 25
2.3.2 SingleInputSingleOutput(SISO)WirelessChannel . . . . . . . . 25
2.3.3 Multi-InputMulti-Output(MIMO)WirelessChannels . . . . . . . 26
2.3.4 TheReceivedElectricField . . . . . . . . . . . . . . . . . . . . . 31
2.3.5 Clarke’sReferenceModel . . . . . . . . . . . . . . . . . . . . . . 34
2.3.6 Jakes’Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
2.3.7 SpatialChannelModel . . . . . . . . . . . . . . . . . . . . . . . . 42
2.3.8 SimulationModel . . . . . . . . . . . . . . . . . . . . . . . . . . 53
2.4 LongTermEvolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
2.4.1 OFDMTransmitterChain . . . . . . . . . . . . . . . . . . . . . . 57
2.4.2 LTEDownlinkRadioFrame . . . . . . . . . . . . . . . . . . . . . 64
2.4.3 SynchronizationSignals . . . . . . . . . . . . . . . . . . . . . . . 64
2.4.4 ReferenceSignalsandAntennaPorts . . . . . . . . . . . . . . . . 67
2.4.5 ChannelEstimation . . . . . . . . . . . . . . . . . . . . . . . . . . 73
2.4.6 LTELinkAdaptation . . . . . . . . . . . . . . . . . . . . . . . . . 79
2.5 LTETransmissionModes . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
2.5.1 TM1SingleAntennaTransmission . . . . . . . . . . . . . . . . . 83
2.5.2 TM2TransmitDiversity . . . . . . . . . . . . . . . . . . . . . . . 84
2.5.3 TM3Open-LoopSpatialMultiplexing . . . . . . . . . . . . . . . . 90
2.5.4 TM4Closed-LoopSpatialMultiplexing . . . . . . . . . . . . . . . 102
2.5.5 TM6SingleLayerClosed-LoopSpatialMultiplexing . . . . . . . . 109
vii
3 PerformanceSimulationSetup 111
3.1 LinkLevelSimulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
3.1.1 DownlinkChannelModelingintheLinkLevelSimulator . . . . . 111
3.1.2 ChannelModelsusedintheSimulator . . . . . . . . . . . . . . . . 118
3.2 SimulatingtheLTEDownlinkusingtheLinkLevelSimulator . . . . . . . 120
3.3 PerformanceMeasurementsandChannelQualityIndicators . . . . . . . . 120
3.3.1 ThroughputMeasurement . . . . . . . . . . . . . . . . . . . . . . 120
3.3.2 CQIandRankMeasurement . . . . . . . . . . . . . . . . . . . . . 121
3.4 SimulationParameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
3.4.1 SystemParameters . . . . . . . . . . . . . . . . . . . . . . . . . . 122
3.4.2 TransmissionParameters . . . . . . . . . . . . . . . . . . . . . . . 124
3.4.3 SimulationDuration . . . . . . . . . . . . . . . . . . . . . . . . . 126
3.4.4 AntennaSimulationParameters . . . . . . . . . . . . . . . . . . . 126
3.4.5 ChannelSimulationParameters . . . . . . . . . . . . . . . . . . . 128
3.4.6 ResourceAllocationandScheduling . . . . . . . . . . . . . . . . . 131
3.4.7 ReceiverAlgorithms . . . . . . . . . . . . . . . . . . . . . . . . . 132
3.4.8 ChannelStateInformation(CSI)ReportingforLinkAdaptation(LA)133
3.5 PerformanceBenchmarks . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
3.5.1 ThroughputPerformanceBenchmarking . . . . . . . . . . . . . . . 135
3.5.2 UEVelocityBenchmarking . . . . . . . . . . . . . . . . . . . . . 135
4 SimulationResults 137
4.1 AntennaConfigurationPerformance . . . . . . . . . . . . . . . . . . . . . 137
4.1.1 BaseStationAntennaConfigurations . . . . . . . . . . . . . . . . 138
4.1.2 MobileStationAntennaConfiguration . . . . . . . . . . . . . . . . 141
4.1.3 SummaryoftheAntennaConfigurations . . . . . . . . . . . . . . 142
4.1.4 TransmissionModesforAntennaConfigurationSimulations . . . . 142
4.1.5 4-Tx 4-Port TM2 vs TM4 rank-1 Throughput Differences at High
andLowAntennaCorrelationusingSCMEandEPAChannelModels144
4.1.6 NumberofAntennasandAntennaPortSimulations . . . . . . . . . 155
4.2 PhaseNoiseEffectsontheLTEDownlink . . . . . . . . . . . . . . . . . . 170
4.2.1 PhaseNoiseModel . . . . . . . . . . . . . . . . . . . . . . . . . . 173
4.2.2 ReferenceSimulationsusingGeneratedPhaseNoiseandthe3GPP
EPAChannelModel . . . . . . . . . . . . . . . . . . . . . . . . . 175
4.2.3 MeasuredPhaseNoiseSimulations . . . . . . . . . . . . . . . . . 179
viii
4.3 EffectsofUEVelocityandFeedbackReportingonTheLTEDownlink . . . 195
4.3.1 PracticalIssuesoftheLinkAdaptationControlLoop . . . . . . . . 195
4.3.2 LTEDownlinkThroughputvsCSIReportingSettingsandUEMo-
bilitySimulations . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
4.3.3 LTEDownlinkSimulationsatHighSpeedTrainVelocities . . . . . 209
4.3.4 HighSpeedTrainResultsandDiscussion . . . . . . . . . . . . . . 211
5 ConclusionandFutureWork 220
5.1 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
5.2 FutureWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
AppendixA 225
A.1 4-bitChannelQualityIndicatorTable . . . . . . . . . . . . . . . . . . . . 225
A.2 ModulationandTransportBlockSizeIndexTableforthePDSCH . . . . . 225
A.3 ResourceBlockGroupSizeversusDownlinkBandwidth(Type0Resource
Allocation) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
AppendixB 229
B.1 Jakes’Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
AppendixC 231
C.1 PeakTheoreticalThroughputforLTEDownlinkTransmissions . . . . . . . 231
C.1.1 Peak Theoretical Throughput for 8 PRB UE Allocation using Sin-
gleCodewordTransmissions . . . . . . . . . . . . . . . . . . . . . 231
C.1.2 TableofPeakTheoreticalThroughputValuesforVariousConfigu-
rationsusedinthisThesis . . . . . . . . . . . . . . . . . . . . . . 232
AppendixD 234
D.1 CorrelationMatricesfor3GPPConformanceTestingChannelModels . . . 234
ListofReferences 236
ix
List of Tables
1.1 LTEUplink/DownlinkThroughputSpeedsversusUserEquipmentCategories 2
2.1 Feature Comparison for SCM, SCME, WIM1, WIM2 Spatial Channel
Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
2.2 EnvironmentParametersfortheUrbanMacroScenario . . . . . . . . . . . 48
2.3 DescriptionoftheSpatialChannelModelAngularParameters . . . . . . . 50
2.4 Description of the Parameters used in the SCME’s Channel TDL Generat-
ingEquation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
2.5 TypicalLTESystemParameters . . . . . . . . . . . . . . . . . . . . . . . 56
2.6 TypesofDownlinkReferenceSignalsDefinedin3GPPLTERel8 . . . . . 68
2.7 CoherenceBandwidthfor3GPPConformanceTestingChannelModels . . 77
2.8 ChannelStateInformationReportedbytheUE . . . . . . . . . . . . . . . 81
2.9 LTETransmissionModes . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
2.10 Codeword-to-LayerMappingforTransmitDiversity(2AntennaPorts) . . . 86
2.11 Codeword-to-LayerMappingforTransmitDiversity(4AntennaPorts) . . . 88
2.12 TM3PDSCHTransmissionScheme . . . . . . . . . . . . . . . . . . . . . 91
2.13 Sub-BandSizevs. SystemBandwidth . . . . . . . . . . . . . . . . . . . . 93
2.14 DownlinkPhysicalLayerParametersSetByParameterUE-category . . . . 94
2.15 DownlinkPhysicalLayerCodeword-to-LayerMapping . . . . . . . . . . . 94
2.16 PrecoderCodebookforTransmissiononTwoAntennaPorts . . . . . . . . 98
2.17 PrecoderCodebookforTransmissiononFourAntennaPortsFrom[1] . . . 101
2.18 TM4PDSCHTransmissionScheme . . . . . . . . . . . . . . . . . . . . . 103
3.1 BaseSimulationParametersforLTEDownlinkThroughputComparisons . 123
3.2 SystemBandwidthusedinEachStudy . . . . . . . . . . . . . . . . . . . . 124
3.3 TransmissionModesusedinEachStudy . . . . . . . . . . . . . . . . . . . 125
3.4 AntennaPortsusedinEachStudy . . . . . . . . . . . . . . . . . . . . . . 125
3.5 ReferenceSignalPowerBoostingusedinEachStudy . . . . . . . . . . . . 126
3.6 ChannelModelsusedinEachStudy . . . . . . . . . . . . . . . . . . . . . 129
x
3.7 UEVelocitiesusedinthisThesis . . . . . . . . . . . . . . . . . . . . . . . 130
3.8 SpectralResourcesAllocatedtotheUEinEachStudy . . . . . . . . . . . 131
3.9 Outer-loopLinkAdaptationSettingsusedinEachStudy . . . . . . . . . . 132
3.10 LinkAdaptationSettingsusedinEachStudy . . . . . . . . . . . . . . . . 134
3.11 Sub-bandCQI/PMIGroupSizeSettingsusedinEachStudy . . . . . . . . 134
4.1 Wavelengths and Antenna Element Spacing of Two Common LTE Fre-
quencyBands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
4.2 BSandMSAntennaConfigurations . . . . . . . . . . . . . . . . . . . . . 143
4.3 SimulationParametersfor4-Tx4-PortTM2andTM4Rank-1Simulations
usingtheSCMEandEPAChannelModels . . . . . . . . . . . . . . . . . . 147
4.4 SimulatedvsTheoreticalThroughputfor4-Tx4-portTM2andTM4rank-1
withHighlyCorrelatedCross-PolarizedAntennasat3km/hr . . . . . . . . 148
4.5 SimulatedvsTheoreticalThroughputfor4-Tx4-portTM2andTM4rank-1
withUncorrelatedCross-PolarizedAntennasat3km/hr . . . . . . . . . . . 148
4.6 Throughputof4-Tx4-PortTM2andTM4rank-1at10dBSNR(EPA) . . . 149
4.7 Throughputof4-Tx4-PortTM2andTM4rank-1at10dBSNR(SCME) . 149
4.8 Gain of 4-Tx 4-Port TM4 rank-1 Over Other Modes and Antenna Config-
urationsat2.5Mbps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
4.9 SimulationParametersfortheAntennaConfigurationSimulations . . . . . 157
4.10 Gain of 4 Transmitters 4-Port TM4 Over Other Number of Antennas at 25
MbpsataUEVelocityof2.1km/hr . . . . . . . . . . . . . . . . . . . . . 158
4.11 Gain of 4 Transmitters 4-Port TM4 Over Other Number of Antennas at 25
MbpsataUEVelocityof20.8km/hr . . . . . . . . . . . . . . . . . . . . . 162
4.12 ThroughputofBestAntennaConfigurationat14dBSNR(2.1km/hr) . . . 166
4.13 SimulationParametersfortheGeneratedPhaseNoiseSimulations . . . . . 177
4.14 PhaseJitterDataSetStatistics . . . . . . . . . . . . . . . . . . . . . . . . 185
4.15 SimulationParametersfortheMeasuredPhaseNoiseSimulations . . . . . 187
4.16 ApproximateMaximumUEVelocitySupportedbyCQIReporting . . . . . 200
4.17 SimulationParametersfortheDownlinkThroughputvsCSIReportingSet-
tingsandUEVelocitySimulations . . . . . . . . . . . . . . . . . . . . . . 203
4.18 Simulation Parameters for the LTE Downlink Throughput in the High
SpeedTrainScenario . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
4.19 DownlinkThroughputatIncreasingUEVelocity . . . . . . . . . . . . . . 213
4.20 AverageCQIIndexatIncreasingUEVelocity . . . . . . . . . . . . . . . . 218
xi