Mobile Cellular Communications with Base Station Antenna Arrays

225 Pages·2008·1.51 MB·English

Mobile Cellular Communications with Base
Station Antenna Arrays:
Spectrum Efficiency, Algorithms and
Propagation Models
Per Zetterberg
TRITA–S3–SB–9712
ISSN 1103–8039
ISRN KTH/SB/R - - 97/12 - - SE
Signal Processing
Department of Signals, Sensors and Systems
Royal Institute of Technology
Stockholm, Sweden
Submitted to the School of Electrical Engineering, Royal Institute of
Technology, in partial fulfillment of the requirements for the degree of
Doctor of Philosophy.

Abstract
This thesis deals with the problem of increasing the spectrum efficiency
of cellular systems, by the use of antenna array base stations. The focus
of the thesis is on downlink transmission in frequency division duplex
systems, i.e., systems with different up and downlink carrier frequency.
In a short summary the thesis:
Proposes five reasonable propagation models.
•
Uses these models to design and analyze three different beamform-
•
ers: Themaximumdesiredpower(MDP),thesummedinterference
tocarrierratiominimizing(SCIR)andthegeneralized-SCIRbeam-
former.
Introduces three capacity enhancement approaches: same sector
•
frequencyreuse(SSFR),reducedclustersizewithoutnulling(RCS-
WON) and reduced cluster size with nulling (RCS-WIN).
Proposeschannelallocation,powercontrol,andbeamformingalgo-
•
rithms for these approaches.
Estimatesthe“outageprobability”(probabilityofinsufficientqual-
•
ity),forSICR-SSFR,SICR-RCS-WONandSICR-RCS-WIN,using
simulations as well as analytical analysis, as a function of critical
parameters.
Investigates the capacity enhancement achieved with the base sta-
•
tionantennaarrayasafunctionofangularspreadingandthenum-
ber of antennas for SICR-SSFR, SICR-RCS-WON and SICR-RCS-
WIN.
Partiallyverifiesthesystemsimulationassumptionsusingrealdata.
•
iv
Combines simulation and experimental results to make likely that
•
three to tenfold capacity enhancement is realistic using 3 18 an-
−
tennaelementsper120-degreesector(incomparisonwithasystem
employing a single antenna per sector). The higher capacity en-
hancements are obtained using the more complex approaches.
Makes a detailed proposal of a simple and robust downlink beam-
•
forming algorithm for realizing RCS-WON in GSM (the MDP
beamformer) .
Simulatesthisbeamformerunderrealisticnetworkconditions,using
•
simulated as well as real data.
Acknowledgment
IwouldliketothankmysupervisorProfessorBj¨ornOttersten,forassign-
ing me to a very interesting and successful project : “spatial diversity in
communications” and for introducing me into the field of statistical sig-
nal processing. The concept of enhancing cellular systems by the use of
antenna arrays (i.e., spatial diversity) has received increasing interest, in
both academia and industry, during the course of the project and it is
my hope that it will continue to do so.
Duringtheacademicyear95/96Iwasluckytobeavisitingresearcher
at the Center for PersonKommunikation (CPK) at Aalborg University
which is headed by Professor Jørgen Bach Andersen. At the CPK I col-
laborated with the TSUNAMI(II) 1 group led by Dr. Preben Mogensen.
I have been allowed to use the data, recorded using the smart antenna
testbed developed by Dr Mogensen’s group in this thesis. The measure-
ment data give the thesis considerably more strength than it would have
without it. Thus, I am greatly indebted to the people who built the
testbed and carried out the measurements : Preben Mogensen, Frank
Frederiksen, Kim Olesen, Sten Leth-Larsen, Henrik Dam, and others.
I would also like to thank NUTEK2 and HCM3 for their financial
support, which has made this thesis possible.
During my entire time as a PhD student I have always had terrific
colleges with whom I have been able to discuss research as well as all
other possible issues. My colleagues have also become my friends, and
we have had great fun on numerous occasions.
1TSUNAMI(II) stands for technology in smart antennas for universal advanced
mobileinfrastructure-part2,andisaprojectsponsoredthroughtheEuropeanCom-
missionsACTSprogram.
2Na¨ringsochteknikutvecklingsverket(theNationalBoardforIndustrialandTech-
nicalDevelopment)
3TheEuropeanCommissionsHumanCapitalandMobilityprogram
vi
I am grateful for the support and confidence that my parents and my
sister have given me.
Finally, I would also like to express my love for my fiance Linda,
and my dear son Samuel who has been with us for the last eight weeks.
Linda has been understandingly patient with my absent mindness and
my “innovative” working schedule.
Contents
1 Introduction 1
1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Thesis Topics . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 Review of the Literature . . . . . . . . . . . . . . . . . . . 5
1.3.1 Channel Modeling . . . . . . . . . . . . . . . . . . 5
1.3.2 Downlink Beamforming . . . . . . . . . . . . . . . 7
1.3.3 Channel Allocation and Capacity Analysis. . . . . 10
1.4 Contributions and Thesis Outline . . . . . . . . . . . . . . 12
1.5 Mathematical Notation . . . . . . . . . . . . . . . . . . . 19
1.6 Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . 20
2 Propagation Modeling 21
2.1 Basic Assumptions . . . . . . . . . . . . . . . . . . . . . . 24
2.1.1 Uplink . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.1.2 Downlink . . . . . . . . . . . . . . . . . . . . . . . 28
2.2 GWSSUS . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.3 Gaussian Angle of Arrival (GAA) . . . . . . . . . . . . . . 31
2.3.1 The GAAO model . . . . . . . . . . . . . . . . . . 32
2.4 The TU and BU Simulation Models . . . . . . . . . . . . 36
2.5 Implications of the Proposed Models for TDD and FDD
Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
2.5.1 Conditions Under Which the Up- and Downlink
Impulse Response are Equal in TDD . . . . . . . . 40
2.5.2 The Fast Fading in Up- and Downlink is Indepen-
dent in FDD . . . . . . . . . . . . . . . . . . . . . 40
2.6 Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
2.A Connection Between the GAA Model and the Conven-
tional Sensor Array Model . . . . . . . . . . . . . . . . . . 44
viii CONTENTS
2.B Thorough Development of the Basic Assumptions . . . . 47
2.B.1 Uplink . . . . . . . . . . . . . . . . . . . . . . . . . 47
2.B.2 Downlink . . . . . . . . . . . . . . . . . . . . . . . 50
2.B.3 Influence of Mutual Coupling . . . . . . . . . . . . 50
2.C Thorough Derivation of the Proposed TU and BU Models 51
2.C.1 The Typical Urban (TU) Model . . . . . . . . . . 51
2.C.2 The Bad Urban (BU) Propagation Model . . . . . 54
2.C.3 Implementation . . . . . . . . . . . . . . . . . . . . 55
2.D PropertiesoftheProposedTUandBUPropagationModels 57
2.D.1 Temporal Properties . . . . . . . . . . . . . . . . . 57
2.D.2 Amplitude Distributions . . . . . . . . . . . . . . . 58
2.D.3 Frequency Correlation . . . . . . . . . . . . . . . . 59
2.D.4 Doppler Spectrums . . . . . . . . . . . . . . . . . . 60
2.D.5 Angle of Arrival Spectrum . . . . . . . . . . . . . . 62
2.E Mixing Model and Measurement Data . . . . . . . . . . . 64
2.F Frequency Separation for Uncorrelated Up- and Downlink 66
2.G The Positions and Gains of the Scatterers in the TU Model 69
3 Techniques for Downlink Enhancement of FDD Systems 73
3.1 Frequency Reuse . . . . . . . . . . . . . . . . . . . . . . . 76
3.1.1 Cellular Geometry and Frequency Allocations . . . 76
3.1.2 Same Sector Frequency Reuse (SSFR) . . . . . . . 78
3.1.3 The SSFR, RCS-WIN and RCS-WON Approaches 79
3.2 Three Downlink Proposals for FDD Cellular Systems . . . 80
3.2.1 The Summed Inverse Interference to Carrier Ratio
Minimizing Beamformer (SICR) . . . . . . . . . . 81
3.3 The SICR-SSFR, SICR-RCS-WIN and SICR-RCS-WON
Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
3.3.1 The SICR-SSFR System . . . . . . . . . . . . . . . 84
3.3.2 The SICR-RCS-WIN/WON Systems . . . . . . . . 86
3.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
3.A Blocking Considerations . . . . . . . . . . . . . . . . . . . 90
4 Capacity Results 93
4.1 Preliminaries . . . . . . . . . . . . . . . . . . . . . . . . . 95
4.2 Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
4.3 Conclusions and Discussion . . . . . . . . . . . . . . . . . 112
4.3.1 Uplink Near-Far Effects and Power Control . . . . 112
4.3.2 Uplink Power Control Downlink Performance De-
pendence . . . . . . . . . . . . . . . . . . . . . . . 113
CONTENTS ix
4.3.3 AgreementBetweenSimulationandAnalyticalRe-
sults . . . . . . . . . . . . . . . . . . . . . . . . . . 113
4.3.4 Capacity Estimates. . . . . . . . . . . . . . . . . . 114
4.A Frequency Reuse (K,S)=(1.5,1) and (K,S)=(2,1) . . . 116
4.B Simulation Procedure . . . . . . . . . . . . . . . . . . . . 117
4.C Analytical Results . . . . . . . . . . . . . . . . . . . . . . 120
4.C.1 SICR-RCS-WIN with e=1 . . . . . . . . . . . . . 122
4.C.2 SICR-RCS-WON (e independent analysis) . . . . . 129
4.C.3 SICR-SSFR . . . . . . . . . . . . . . . . . . . . . . 130
4.C.4 Lemmas to Section 4.C.3 . . . . . . . . . . . . . . 134
4.D Instantaneous Outage Probability . . . . . . . . . . . . . 137
4.E Distribution of θ . . . . . . . . . . . . . . . . . . . . . . 138
i,i
4.F Proof of (4.54) . . . . . . . . . . . . . . . . . . . . . . . . 139
4.F.1 Derivation of (4.91) . . . . . . . . . . . . . . . . . 139
4.F.2 Derivation of Equation (4.92) . . . . . . . . . . . . 140
4.G Derivation of Equation (4.93) . . . . . . . . . . . . . . . . 144
5 The Generalized SICR Beamformer 145
5.1 Some Notations and Assumptions . . . . . . . . . . . . . . 146
5.2 Derivation . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
6 A Downlink Beam-Steering Algorithm for GSM 149
6.1 Some Notations and Assumptions . . . . . . . . . . . . . . 151
6.2 The MDP Beamformer . . . . . . . . . . . . . . . . . . . . 153
6.2.1 Basic Approach . . . . . . . . . . . . . . . . . . . . 153
6.2.2 Some Manipulations of the Criterion Function . . 155
6.2.3 Implementation . . . . . . . . . . . . . . . . . . . . 156
6.2.4 Analysis of the Impact of Interference . . . . . . . 158
6.2.5 Why Maximize The Desired Power on a Logarith-
mic Scale ? . . . . . . . . . . . . . . . . . . . . . . 164
6.3 Simulation and Measurement Results . . . . . . . . . . . . 165
6.3.1 Performance Measures . . . . . . . . . . . . . . . . 165
6.3.2 Simulations . . . . . . . . . . . . . . . . . . . . . . 168
6.4 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 170
6.A Simulations Using the “Beamlink” Package . . . . . . . . 176
6.A.1 In General. . . . . . . . . . . . . . . . . . . . . . . 176
6.A.2 Configuration of Beamlink in this Thesis. . . . . . 179
x CONTENTS
7 Experimental Performance Results 183
7.1 Experimental Setup . . . . . . . . . . . . . . . . . . . . . 184
7.2 Analysis Method . . . . . . . . . . . . . . . . . . . . . . . 185
7.2.1 Details . . . . . . . . . . . . . . . . . . . . . . . . . 190
7.3 Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
7.4 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 197
8 Thesis Summary and Future Research Issues 199
8.1 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
8.2 Future Research Issues . . . . . . . . . . . . . . . . . . . . 203