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Evaluation of HSDPA and LTE: From Testbed Measurements to System Level Performance

Evaluation of HSDPA and LTE: From Testbed Measurements to System Level Performance

Markus Rupp, Sebastian Caban, Christian Mehlführer, Martin Wrulich

ISBN: 978-1-119-95470-5

Nov 2011

408 pages

Description

This book explains how the performance of modern cellular wireless networks can be evaluated by measurements and simulations

With the roll-out of LTE, high data throughput is promised to be available to cellular users. In case you have ever wondered how high this throughput really is, this book is the right read for you: At first, it presents results from experimental research and simulations of the physical layer of HSDPA, WiMAX, and LTE. Next, it explains in detail how measurements on such systems need to be performed in order to achieve reproducible and repeatable results. The book further addresses how wireless links can be evaluated by means of standard-compliant link-level simulation. The major challenge in this context is their complexity when investigating complete wireless cellular networks. Consequently, it is shown how system-level simulators with a higher abstraction level can be designed such that their results still match link-level simulations. Exemplarily, the book finally presents optimizations of wireless systems over several cells.

This book:

  • Explains how the performance of modern cellular wireless networks can be evaluated by measurements and simulations
  • Discusses the concept of testbeds, highlighting the challenges and expectations when building them
  • Explains measurement techniques, including the evaluation of the measurement quality by statistical inference techniques
  • Presents throughput results for HSDPA, WiMAX,  and LTE
  • Demonstrates simulators at both, link- level and system-level
  • Provides system-level and link-level simulators (for WiMAX and LTE) on an accompanying website (https://www.nt.tuwien.ac.at/downloads/featured-downloads)

This book is an insightful guide for researchers and engineers working in the field of mobile radio communication as well as network planning. Advanced students studying related courses will also find the book interesting.

About the Authors xiii

About the Contributors xv

Preface xvii

Acknowledgments xxiii

List of Abbreviations xxv

Part I CELLULAR WIRELESS STANDARDS

Introduction 3

References 4

1 UMTS High-Speed Downlink Packet Access 5

1.1 Standardization and Current Deployment of HSDPA 5

1.2 HSDPA Principles 6

1.2.1 Network Architecture 7

1.2.2 Physical Layer 9

1.2.3 MAC Layer 13

1.2.4 Radio Resource Management 14

1.2.5 Quality of Service Management 16

1.3 MIMO Enhancements of HSDPA 17

1.3.1 Physical Layer Changes for MIMO 19

1.3.2 Precoding 21

1.3.3 MAC Layer Changes for MIMO 25

1.3.4 Simplifications of the Core Network 26

References 26

2 UMTS Long-Term Evolution 29

Contributed by Josep Colom Ikuno

2.1 LTE Overview 29

2.1.1 Requirements 29

2.2 Network Architecture 31

2.3 LTE Physical Layer 33

2.3.1 LTE Frame Structure 34

2.3.2 Reference and Synchronization Symbols 36

2.3.3 MIMO Transmission 37

2.3.4 Modulation and Layer Mapping 39

2.3.5 Channel Coding 41

2.3.6 Channel Adaptive Feedback 45

2.4 MAC Layer 46

2.4.1 Hybrid Automatic Repeat Request 46

2.4.2 Scheduling 47

2.5 Physical, Transport, and Logical Channels 48

References 51

Part II TESTBEDS FOR MEASUREMENTS

Introduction 57

Reference 58

3 On Building Testbeds 59

3.1 Basic Idea 60

3.2 Transmitter 61

3.3 Receiver 63

3.4 Synchronization 65

3.5 Possible Pitfalls 67

3.5.1 Digital Baseband Hardware 67

3.5.2 Tool and Component Selection 68

3.5.3 Analog RF Front Ends 69

3.5.4 Cost 70

3.5.5 Matlab® Code and Testbeds 70

3.6 Summary 71

References 72

4 Quasi-Real-Time Testbedding 75

4.1 Basic Idea 75

4.2 Problem Formulation 77

4.3 Employing the Basic Idea 78

4.4 Data Collection 80

4.4.1 More Sophisticated Sampling Techniques 81

4.4.2 Variance Reduction Techniques 84

4.4.3 Bias 85

4.4.4 Outliers 86

4.4.5 Parameter Estimation 87

4.5 Evaluating and Summarizing the Data 88

4.6 Statistical Inference 90

4.6.1 Inferring the Population Mean 90

4.6.2 Precision and Sample Size 91

4.6.3 Reproducibility and Repeatability 92

4.7 Measurement Automation 95

4.8 Dealing with Feedback and Retransmissions 96

References 97

Part III EXPERIMENTAL LINK-LEVEL EVALUATION

Introduction 101

5 HSDPA Performance Measurements 103

5.1 Mathematical Model of the Physical Layer 104

5.1.1 System Model for the Channel Estimation 106

5.1.2 System Model for the Equalizer Calculation 106

5.2 Receiver 107

5.2.1 Channel Estimation 107

5.2.2 Equalizer 112

5.2.3 Further Receiver Processing 113

5.3 Quantized Precoding 113

5.4 CQI and PCI Calculation 115

5.4.1 HS-PDSCH Interference 115

5.4.2 Pilot Interference 116

5.4.3 Synchronization and Control Channel Interference 116

5.4.4 Post-equalization Noise and SINR 118

5.4.5 SINR to CQI Mapping 119

5.5 Achievable Mutual Information 121

5.6 Measurement Results 124

5.6.1 Alpine Scenario 125

5.6.2 Urban Scenario 128

5.6.3 Discussion of the Implementation Loss 130

5.7 Summary 131

References 132

6 HSDPA Antenna Selection Techniques 139

Contributed by Jos´e Antonio Garc´ıa-Naya

6.1 Existing Research 141

6.2 Receive Antenna Selection 142

6.2.1 Antenna Selection Based on System Throughput 143

6.2.2 Hardware Aspects of Antenna Selection 143

6.3 An Exemplary Measurement and its Results 144

6.3.1 Urban Scenario 144

6.3.2 Experimental Assessment of Antenna Selection in HSDPA 145

6.3.3 Measurement Results and Discussion 147

6.4 Summary 148

References 149

7 HSDPA Antenna Spacing Measurements 153

7.1 Problem Formulation 153

7.2 Existing Research 154

7.3 Experimental Setup 155

7.4 Measurement Methodology 157

7.4.1 Inferring the Mean Scenario Throughput 157

7.4.2 Issues Requiring Special Attention 158

7.5 Measurement Results and Discussion 160

7.5.1 Equal Polarization Versus Cross-Polarization 160

7.5.2 Channel Capacity 160

7.5.3 Channel Capacity Versus Mutual Information 162

7.5.4 Mutual Information Versus Achievable Mutual Information 162

7.5.5 Achievable Mutual Information Versus Throughput 163

7.5.6 Throughput 163

7.6 Different Transmit Power Levels and Scenarios 163

References 164

8 Throughput Performance Comparisons 167

8.1 Introduction 167

8.2 Cellular Systems Investigated: WiMAX and HSDPA 168

8.2.1 WiMAX and HSDPA 168

8.2.2 Throughput Bounds and System Losses 169

8.3 Measurement Methodology and Setup 172

8.4 Measurement Results 173

8.4.1 WiMAX Results 173

8.4.2 HSDPA Results in Standard-Compliant Setting 177

8.4.3 HSDPA Results in Advanced Setting 179

8.5 Summary 179

References 182

9 Frequency Synchronization in LTE 183

Contributed by Qi Wang

9.1 Mathematical Model 184

9.2 Carrier Frequency Offset Estimation in LTE 186

9.2.1 Standardized Training Symbols in LTE 186

9.2.2 Maximum Likelihood Estimators 188

9.3 Performance Evaluation 191

9.3.1 Estimation Performance 192

9.3.2 Post-FFT SINR 194

9.3.3 Post-equalization SINR and Throughput 195

References 199

10 LTE Performance Evaluation 201

Contributed by Stefan Schwarz

10.1 Mathematical Model of the Physical Layer 202

10.2 Receiver 203

10.2.1 Channel Estimation 204

10.2.2 Data Detection 205

10.2.3 Further Receiver Processing 206

10.3 Physical Layer Modeling 206

10.3.1 Post-equalization SINR 207

10.3.2 SINR Averaging 207

10.4 User Equipment Feedback Calculation 208

10.4.1 User Equipment Feedback Indicators 208

10.4.2 Calculation of the CQI, PMI, and RI 210

10.5 Practical Throughput Bounds 216

10.5.1 Channel Capacity 216

10.5.2 Open-Loop Mutual Information 217

10.5.3 Closed-Loop Mutual Information 218

10.5.4 BICM Bounds 219

10.5.5 Achievable Throughput Bounds 222

10.5.6 Prediction of the Optimal Performance 223

10.6 Simulation Results 224

10.6.1 SISO Transmission 225

10.6.2 OLSM Transmission 227

10.6.3 CLSM Transmission 229

References 230

Part IV SIMULATORS FOR WIRELESS SYSTEMS

Introduction 237

References 240

11 LTE Link- and System-Level Simulation 243

Contributed by Josep Colom Ikuno

11.1 The Vienna LTE Link Level Simulator 245

11.1.1 Structure of the Simulator 245

11.1.2 Complexity 247

11.2 The Vienna LTE System Level Simulator 250

11.2.1 Structure of the Simulator 250

11.2.2 Simulator Implementation 252

11.2.3 Complexity 253

11.3 Validation of the Simulators 255

11.3.1 3GPP Minimum Performance Requirements 257

11.3.2 Link- and System-Level Cross-Comparison 257

11.4 Exemplary Results 259

11.4.1 Link-Level Throughput 259

11.4.2 LTE Scheduling 262

References 265

12 System-Level Modeling for MIMO-Enhanced HSDPA 271

12.1 Concept of System-Level Modeling 271

12.2 Computationally Efficient Link-Measurement Model 273

12.2.1 Receive Filter 274

12.2.2 WCDMA MIMO in the Network Context 276

12.2.3 Equivalent Fading Parameters Description 278

12.2.4 Generation of the Equivalent Fading Parameters 284

12.2.5 Influence of Non-Data Channels 286

12.2.6 Resulting SINR Description 287

12.3 Link-Performance Model 288

12.3.1 Link-Performance Model Concept 289

12.3.2 Training and Validation of the Model 293

References 296

Part V SIMULATION-BASED EVALUATION FOR WIRELESS SYSTEMS

Introduction 301

13 Optimization of MIMO-Enhanced HSDPA 303

13.1 Network Performance Prediction 303

13.1.1 Simulation Setup 303

13.1.2 Single Network Scenario Investigation 304

13.1.3 Average Network Performance 306

13.2 RLC-Based Stream Number Decision 310

13.2.1 UE Decision 310

13.2.2 RLC Decision 311

13.2.3 System-Level Simulation Results 311

13.3 Content-Aware Scheduling 313

13.3.1 Video Packet Prioritization in HSDPA 313

13.3.2 Content-Aware Scheduler 314

13.3.3 Simulation Results 315

13.4 CPICH Power Optimization 316

13.4.1 System-Level Modeling of the CPICH Influence 317

13.4.2 CPICH Optimization in the Cellular Context 318

References 321

14 Optimal Multi-User MMSE Equalizer 325

14.1 System Model 326

14.2 Intra-Cell Interference Aware MMSE Equalization 330

14.2.1 Interference Suppression Capability 332

14.3 The Cell Precoding State 334

14.3.1 Training-Sequence-Based Precoding State Estimation 336

14.3.2 Blind Precoding State Estimation 337

14.3.3 Estimator Performance 339

14.4 Performance Evaluation 340

14.4.1 Physical-Layer Simulation Results 340

14.4.2 System-Level Simulation Results 341

References 343

15 LTE Advanced Versus LTE 347

Contributed by Stefan Schwarz

15.1 IMT-Advanced and 3GPP Performance Targets 348

15.2 Radio Interface Enhancements 349

15.2.1 Bandwidth Extension 349

15.2.2 Enhanced MIMO 350

15.2.3 Uplink Improvements 351

15.2.4 Beyond Release 10 352

15.3 MIMO in LTE Advanced 354

15.3.1 Codebook-Based Precoding 354

15.3.2 Non-Codebook-Based Precoding 356

15.4 Physical-Layer Throughput Simulation Results 359

15.4.1 Eight-Antenna Transmission 359

15.4.2 Comparison between LTE and LTE Advanced 363

15.4.3 Comparison of SU-MIMO and MU-MIMO 363

References 366

Index 369