DIGITAL RADIO SYSTEM DESIGN Grigorios Kalivas University of Patras, Greece

©WILEY A John Wiley and Sons, Ltd, Publication

Contents

Preface xiii

1 Radio Communications: System Concepts, Propagation and Noise 1

1.1 Digital Radio Systems and Wireless Applications 2 1.1.1 Cellular Radio Systems 2 1.1.2 Short-and Medium-range Wireless Systems 3 1.1.3 Broadband Wireless Access 6 1.1.4 Satellite Communications 6

1.2 Physical Layer of Digital Radio Systems 7 1.2.1 Radio Platform 7 1.2.2 Baseband Platform 9 1.2.3 Implementation Challenges 10

1.3 Linear Systems and Random Processes 11 1.3.1 Linear Systems and Expansion of Signals in Orthogonal Basis Functions 11 1.3.2 Random Processes 12 1.3.3 White Gaussian Noise and Equivalent Noise Bandwidth 15 1.3.4 Deterministic and Random Signals of Bandpass Nature 16

1.4 Radio Channel Characterization 19 1.4.1 Large-scale Path Loss 19 1.4.2 Shadow Fading 22 1.4.3 Multipath Fading in Wideband Radio Channels 22

1.5 Nonlinearity and Noise in Radio Frequency Circuits and Systems 32 1.5.1 Nonlinearity 32 1.5.2 Noise 38

1.6 Sensitivity and Dynamic Range in Radio Receivers 44 1.6.1 Sensitivity and Dynamic Range 44 1.6.2 Link Budget and its Effect on the Receiver Design 44

1.7 Phase-locked Loops 46 1.7.1 Introduction 46 1.7.2 Basic Operation of Linear Phase-locked Loops 46 1.7.3 The Loop Filter 48 1.7.4 Equations and Dynamic Behaviour of the Linearized PLL 50 1.7.5 Stability of Phase-locked Loops 53 1.7.6 Phase Detectors 55 1.7.7 PLL Performance in the Presence of Noise 59 1.7.8 Applications of Phase-locked Loops 60 References 62

Contents

2 Digital Communication Principles 65

2.1 Digital Transmission in AWGN Channels 65 2.1.1 Demodulation by Correlation 65 2.1.2 Demodulation by Matched Filtering 67 2.1.3 The Optimum Detector in the Maximum Likelihood Sense 69 2.1.4 Techniques for Calculation of Average Probabilities of Error 72 2.1.5 M-ary Pulse Amplitude Modulation (РАМ) 73 2.1.6 Bandpass Signalling 75 2.1.7 M-ary Phase Modulation 82 2.1.8 Offset QPSK 89 2.1.9 Quadrature Amplitude Modulation 90 2.1.10 Coherent Detection for Nonideal Carrier Synchronization 93 2.1.11 M-ary Frequency Shift Keying 96 2.1.12 Continuous Phase FSK 98 2.1.13 Minimum Shift Keying 103 2.1.14 Noncoherent Detection 106 2.1.15 Differentially Coherent Detection (M-DPSK) 107

2.2 Digital Transmission in Fading Channels 112 2.2.1 Quadrature Amplitude Modulation 112 2.2.2 M-PSK Modulation 113 2.2.3 M-FSK Modulation 113 2.2.4 Coherent Reception with Nonideal Carrier Synchronization 114 2.2.5 Noncoherent M-FSK Detection 116

2.3 Transmission Through Band-limited Channels 117 2.3.1 Introduction 117 2.3.2 Baseband Transmission Through Bandlimited Channels 120 2.3.3 Bandlimited Signals for Zero ISI 122 2.3.4 System Design in Band-limited Channels of Predetermined Frequency Response 125

2.4 Equalization 128 2.4.1 Introduction 128 2.4.2 Sampled-time Channel Model with ISI and Whitening Filter 131 2.4.3 Linear Equalizers 134 2.4.4 Minimum Mean Square Error Equalizer 136 2.4.5 Detection by Maximum Likelihood Sequence Estimation 137 2.4.6 Decision Feedback Equalizer 138 2.4.7 Practical Considerations 139 2.4.8 Adaptive Equalization 140

2.5 Coding Techniques for Reliable Communication 141 2.5.1 Introduction 141 2.5.2 Benefits of Coded Systems 143 2.5.3 Linear Block Codes 143 2.5.4 Cyclic Codes 145

2.6 Decoding and Probability of Error 147 2.6.1 Introduction 147 2.6.2 Convolutional Codes 151 2.6.3 Maximum Likelihood Decoding 154 2.6.4 The Viterbi Algorithm for Decoding 156 2.6.5 Transfer Function for Convolutional Codes 157 2.6.6 Error Performance in Convolutional Codes 158

Contents ix

2.6.7 Turbo Codes 159 2.6.8 Coded Modulation 162 2.6.9 Coding and Error Correction in Fading Channels 164 References 168

3 RF Transceiver Design 173

3.1 Useful and Harmful Signals at the Receiver Front-End 173 3.2 Frequency Downconversion and Image Reject Subsystems 175

3.2.1 Hartley Image Reject Receiver 177 3.2.2 Weaver Image Reject Receiver 180

3.3 The Heterodyne Receiver 183 3.4 The Direct Conversion Receiver 185

3.4.1 DC Offset 186 3.4.2 1-Q Mismatch 188 3.4.3 Even-Order Distortion 189 3.4.4 1//Noise 189

3.5 Current Receiver Technology 190 3.5.1 Image Reject Architectures 190 3.5.2 The Direct Conversion Architecture 206

3.6 Transmitter Architectures 208 3.6.1 Information Modulation and Baseband Signal Conditioning 209 3.6.2 Two-stage Up-con version Transmitters 210 3.6.3 Direct Upconversion Transmitters 211 References 211

4 Radio Frequency Circuits and Subsystems 215

4.1 Role of RF Circuits 216 4.2 Low-noise Amplifiers 219

4.2.1 Main Design Parameters of Low-noise Amplifiers 219 4.2.2 LNA Configurations and Design Trade-offs 222

4.3 RF Receiver Mixers 227 4.3.1 Design Considerations for RF Receiver Mixers 227 4.3.2 Types of Mixers 228 4.3.3 Noise Figure 232 4.3.4 Linearity and Isolation 235

4.4 Oscillators 235 4.4.1 Basic Theory 235 4.4.2 High-frequency Oscillators 239 4.4.3 Signal Quality in Oscillators 241

4.5 Frequency Synthesizers 243 4.5.1 Introduction 243 4.5.2 Main Design Aspects of Frequency Synthesizers 244 4.5.3 Synthesizer Architectures 247 4.5.4 Critical Synthesizer Components and their Impact on the System Performance 253 4.5.5 Phase Noise 256

4.6 Downconverter Design in Radio Receivers 258 4.6.1 Interfaces of the LNA and the Mixer 258 4.6.2 Local Oscillator Frequency Band and Impact of Spurious Frequencies 261

X Contents

4.6.3 Matching at the Receiver Front-end 261 4.7 RF Power Amplifiers 263

4.7.1 General Concepts and System Aspects 263 4.7.2 Power Amplifier Configurations 264 4.7.3 Impedance Matching Techniques for Power Amplifiers 271 4.7.4 Power Amplifier Subsystems for Linearization 273 References 273

5 Synchronization, Diversity and Advanced Transmission Techniques 277

5.1 TFR Timing and Frequency Synchronization in Digital Receivers 277 5.1.1 Introduction 277 5.1.2 ML Estimation (for Feedback and Feed-forward) Synchronizers 280 5.1.3 Feedback Frequency/Phase Estimation Algorithms 282 5.1.4 Feed-forward Frequency/Phase Estimation Algorithms 286 5.1.5 Feedback Timing Estimation Algorithms 291 5.1.6 Feed-forward Timing Estimation Algorithms 293

5.2 Diversity 295 5.2.1 Diversity Techniques 295 5.2.2 System Model 296 5.2.3 Diversity in the Receiver 297 5.2.4 Implementation Issues 302 5.2.5 Transmitter Diversity 304

5.3 OFDM Transmission 306 5.3.1 Introduction 306 5.3.2 Transceiver Model 309 5.3.3 OFDM Distinct Characteristics 312 5.3.4 OFDM Demodulation 313 5.3.5 Windowing and Transmitted Signal 314 5.3.6 Sensitivities and Shortcomings of OFDM 315 5.3.7 Channel Estimation in OFDM Systems 339

5.4 Spread Spectrum Systems 342 5.4.1 Introduction and Basic Properties 342 5.4.2 Direct Sequence Spread Spectrum Transmission and Reception 348 5.4.3 Frequency Hopping SS Transmission and Reception 350 5.4.4 Spread Spectrum for Multiple Access Applications 352 5.4.5 Spreading Sequences for Single-user and Multiple Access DSSS 358 5.4.6 Code Synchronization for Spread Spectrum Systems 363 5.4.7 The RAKE Receiver 365 References 368

6 System Design Examples 371

6.1 The DECT Receiver 371 6.1.1 The DECT Standard and Technology 371 6.1.2 Modulation and Detection Techniques for DECT 372 6.1.3 A DECT Modem for a Direct Conversion Receiver Architecture 375

6.2 QAM Receiver for 6 IMb/s Digital Microwave Radio Link 394 6.2.1 System Description 394 6.2.2 Transmitter Design 396

Contents XI

6.2.3 Receiver Design 6.2.4 Simulation Results 6.2.5 Digital Modem Implementation OFDM Transceiver System Design 6.3.1 Introduction 6.3.2 Channel Estimation in Hiperlan/2 6.3.3 Timing Recovery 6.3.4 Frequency Offset Correction 6.3.5 Implementation and Simulation References

397 403 406 416 416 418 423 424 435 438

Index 441