Single- And Multi-Carrier Quadrature Amplitude Modulation Principles and Applications for Pe... Book

Preface Acknowledgements 1 Introduction and Background 1.1 Modulation Methods 1.2 History of QAM 1.2.1 Determining the optimum constellation 1.2.1.1 Coherent and non-coherent reception 1.2.1.2 Clock recovery 1.2.1.3 The Type I, II and III constellations 1.2.2 Satellite links 1.2.2.1 Odd-bit constellations 1.2.3 QAM modern implementation 1.2.3.1 Non-linear amplification 1.2.3.2 Frequency selective fading and channel equalisers 1.2.3.3 Filtering 1.2.4 Advanced prototypes 1.2.5 QAM for mobile radio 1.3 Orthogonal Frequency Division Multiplexing Based QAM 1.3.1 History of OFDM 1.3.2 Peak-to-mean power ratio 1.3.3 Synchronisation 1.3.4 OFDM/CDMA 1.3.5 Adaptive antennas 1.3.6 OFDM applications 1.4 Summary 1.5 Outline of Topics 2 Communications Channels 2.1 Fixed Communication Channels 2.1.1 Introduction 2.1.2 Fixed channel types 2.1.3 Characterisation of noise 2.2 Telephone Channels 2.3 Mobile Radio Channels 2.3.1 Introduction 2.3.2 Equivalent baseband and passband systems 2.3.3 Gaussian mobile radio channel 2.3.4 Narrow band fading channels 2.3.4.1 Propagation path loss law 2.3.4.2 Slow fading statistics 2.3.4.3 Fast fading statistics 2.3.4.4 Doppler spectrum 2.3.4.5 Simulation of narrowband channels 2.3.4.5.1 Frequency domain fading simulation 2.3.4.5.2 Time domain fading simulation 2.3.4.5.3 Box-Müller algorithm of AWGN generation 2.3.5 Wideband channels 2.3.5.1 Modelling of wideband channels 2.4 Mobile Satellite Propagation 2.4.1 Fixed-link satellite channels 2.4.2 Satellite-to-mobile channels 2.5 Summary 3 Introduction to Modems 3.1 Analogue-to-Digital Conversion 3.2 Mapping 3.3 Filtering 3.4 Modulation and Demodulation 3.5 DataRecovery 3.6 Summary 4 Basic QAM Techniques 4.1 Constellations for Gaussian Channels 4.2 General Pulse Shaping Techniques 4.2.1 Baseband equivalent system 4.2.2 Nyquist filtering 4.2.3 Raised cosine Nyquist filtering 4.2.4 The choice of roll-off factor 4.2.5 Optimum transmit and receive filtering 4.2.6 Characterisation of ISI by eye diagrams 4.2.7 Non-linear filtering 4.3 Methods of Generating QAM 4.3.1 Generating conventional QAM 4.3.2 Superposed QAM 4.3.3 Offset QAM 4.3.4 Non-linear amplification 4.4 Methods of Detecting QAM Signals 4.4.1 Threshold detection of QAM 4.4.2 Matched filtered detection 4.4.3 Correlation receiver 4.5 Linearisation of Power Amplifiers 4.5.1 The linearisation problem 4.5.2 Linearisation by predistortion [1] 4.5.2.1 The predistortion concept 4.5.2.2 Predistorter description 4.5.2.3 Predistorter coefficient adjustment 4.5.2.4 Predistorter performance 4.5.3 Postdistortion of NLA-QAM [2] 4.5.3.1 The postdistortion concept 4.5.3.2 Postdistorter description 4.5.3.3 Postdistorter coefficient adaptation 4.5.3.4 Postdistorter performance 4.6 Non-differential Coding for Square QAM 4.7 Differential Coding for Square QAM 4.8 Summary 5 Square QAM 5.1 Decision Theory 5.2 QAM Modulation and Transmission 5.3 16-QAM Demodulation in AWGN 5.4 64-QAM Demodulation in AWGN 5.5 Summary 6 Clock and Carrier Recovery 6.1 Introduction 6.2 Clock Recovery 6.2.1 Times-two clock recovery 6.2.2 Early-late clock recovery 6.2.3 Zero-crossing clock recovery 6.2.4 Synchroniser 6.3 Carrier Recovery 6.3.1 Times-n carrier recovery 6.3.2 Decision directed carrier recovery 6.3.2.1 Frequency and phase detection systems 6.4 Summary 7 Trained and Blind Equaliser Techniques 7.1 Introduction 7.2 Linear Equalisers 7.2.1 Zero-forcing equalisers 7.2.2 Least mean squared equalisers 7.2.3 Decision directed adaptive equalisers 7.3 Decision Feedback Equalisers 7.4 Fast Converging Equalisers 7.4.1 Least squares method 7.4.2 Recursive Least Squares Method [3] 7.4.2.1 Cost function weighting 7.4.2.2 Recursive correlation update 7.4.2.3 The Ricatti equation of RLS estimation 7.4.2.4 Recursive equaliser coefficient update 7.5 Adaptive Equalisers for QAM 7.6 Viterbi Equalisers 7.6.1 Partial response modulation 7.6.2 Viterbi equalisation 7.7 Overview of Blind Equalizers 7.7.1 Introduction 7.7.2 Historical background 7.7.3 Blind equalization principles 7.7.4 Bussgang blind equalizers 7.7.4.1 Sato's algorithm [4] 7.7.4.2 Constant modulus algorithm [5] 7.7.5 Modified constant modulus algorithm [6] 7.7.5.1 Benveniste-Goursat algorithm [7] 7.7.5.2 Stop-and-Go algorithm [8] 7.7.6 Convergence issues 7.7.7 Joint channel and data estimation techniques 7.7.8 Using second-order cyclostationary statistics 7.7.9 Polycepstra based equalization 7.7.10 Complexity evaluation 7.7.11 Performance results 7.7.11.1 Channel models 7.7.11.2 Learning Curves 7.7.11.3 Phasor diagrams 7.7.11.4 Gaussian channel 7.7.12 Simulations with decision-directed switching 7.8 Summary 7.9 Appendix: Differentiation with Respect to a Vector 7.9.1 An illustrative example: CMA cost-function minimization 7.10 Appendix: Polycepstra definitions 8 Trellis Coded Modulation 8.1 Introduction 8.2 TCM Fundamentals 8.3 8-PSK TCM 8.4 16-QAM TCM 8.5 TCM Under Phase Rotation 8.6 Summary 9 QAM Modems 9.1 Introduction 9.2 Transmission Bit Rate Limits 9.3 V.29 Modem 9.3.1 Signal constellation 9.3.2 Training signals 9.3.3 Scrambling and descrambling 9.3.4 Channel equalisation and synchronisation 9.4 V.32 Modem 9.4.1 General features 9.4.2 Signal constellation and bitmapping 9.4.2.1 Non-redundant 16-QAM 9.4.2.2 Trellis coded 32-QAM 9.4.3 Scrambler and descrambler 9.5 V.33 Modem 9.5.1 General features 9.5.2 Signal constellations and Bitmapping 9.5.3 Synchronising signals 9.6 Summary 10 Square QAM for fading channels 10.1 16-QAM Performance 10.2 64-QAM Performance 10.3 Reference Assisted Coherent QAM 10.3.1 Transparent tone in band modulation [9] 10.3.1.1 Introduction 10.3.1.2 Principles of TTIB 10.3.1.3 TTIB subcarrier recovery 10.3.1.4 TTIB schemes using quadrature mirror filters 10.3.1.5 Residual frequency error compensation [10] 10.3.1.6 TTIB system parameters [11] 10.3.2 Pilot symbol assisted modulation [12] 10.3.2.1 Introduction 10.3.2.2 PSAM system description 10.3.2.3 Channel gain estimation 10.3.2.4 PSAM parameters 10.3.2.5 PSAM performance 10.4 Summary 11 Star QAM 11.1 Introduction 11.2 Star QAM Transmissions 11.2.1 Differential coding 11.2.2 Differential decoding 11.2.3 Effect of oversampling 11.2.4 Star 16-QAM performance 11.3 Trellis Coded Modulation for QAM 11.4 Block Coding 11.5 64-level TCM 11.6 Bandwidth Efficient Coding Results 11.7 Overall Coding Strategy 11.7.1 Square 16-QAM/PSAM/TCM scheme 11.8 Distorted Constellation Star QAM 11.8.1 Introduction 11.8.2 Distortion of the star 11.8.2.1 Amplitude distortion 11.8.2.2 Phase variations 11.9 Practical Considerations 11.9.1 Introduction 11.9.2 Hardware imperfections 11.9.2.1 Quantisation levels 11.9.2.2 I-Q crosstalk 11.9.2.3 Oversampling ratio 11.9.2.4 AM-AM and AM-PM distortion 11.10Summary 12 Timing Recovery for Mobile Radio 12.1 Introduction 12.2 Times-two Clock Recovery for QAM 12.3 Early-Late Clock Recovery 12.4 Modified Early-Late Clock Recovery 12.5 Clock Recovery in the Presence of ISI 12.5.1 Wideband channel models 12.5.2 Clock recovery in two-path channels 12.5.2.1 Case of ??? nT 12.5.2.2 Case of ??? = nT 12.5.3 Clock recovery performance in smeared ISI 12.6 Implementation Details 12.7 Carrier Recovery 12.8 Summary 13 Variable Rate QAM 13.1 Introduction 13.2 Variable QAM Constellations 13.3 The RSSI Switching System 13.3.1 Results 13.4 The Error Detector Switching System 13.4.1 Results 13.5 Co-channel Interference 13.6 Application to a DECT-Type System 13.7 Summary 14 Wideband QAM Transmissions 14.1 Introduction 14.2 The RAKE Combiner 14.3 The Proposed Equaliser 14.3.1 Linear equaliser 14.3.2 Iterative equaliser system 14.3.2.1 The one-symbol window equaliser 14.3.2.2 The limited correction DFE 14.3.3 Use of error correction coding 14.4 Diversity in the Wideband System 14.5 Summary 15 Quadrature-Quadrature AM 15.1 Introduction 15.2 Q2PSK 15.3 Q2AM 15.3.1 Square 16-QAM 15.3.2 Star 16-QAM 15.4 Spectral Efficiency 15.5 Bandlimiting 16-Q2AM 15.6 Results 15.7 Summary 16 Spectral Efficiency of QAM 16.1 Introduction 16.2 Efficiency in Large Cells 16.3 Spectrum Efficiency in Microcells 16.3.1 Microcellular clusters 16.3.2 System design for microcells 16.3.3 Microcellular radio capacity 16.3.4 Modulation schemes for microcells 16.4 Summary 17 QAM Speech Systems 17.1 Introduction 17.2 Modem Schemes 17.2.1 GMSK Modulation 17.2.2 ???-DQPSK Modulation 17.3 Speech Codecs 17.3.1 Adaptive Differential Pulse Code Modulation 17.3.2 Analysis-by-synthesis speech coding 17.3.2.1 The RPE-LTP Speech Encoder 17.3.2.2 The RPE-LTP Speech Decoder 17.4 Speech Quality Measures 17.5 Discontinuous Transmission 17.6 Channel Coding and Bit-mapping 17.7 Speech Transmission Systems 17.8 Packet Reservation Multiple Access 17.8.1 PRMA performance 17.9 Summary 18 Introduction to OFDM 18.1 Introduction 18.2 Principles of QAM-OFDM 18.3 Modulation by DFT 18.4 Transmission via Bandlimited Channels 18.5 Generalised Nyquist Criterion 18.6 Basic OFDM Modem Implementations 18.7 Cyclic OFDM Symbol Extension 18.8 Reducing MDI by Compensation 18.8.1 Transient system analysis 18.8.2 Recursive MDI compensation 18.9 Adaptive Channel Equalisation 18.10OFDM Bandwidth Efficiency 18.11Summary 19 OFDM Transmission over Gaussian Channels 19.1 Orthogonal Frequency Division Multiplexing 19.1.1 History 19.1.1.1 Peak-to-mean power ratio 19.1.1.2 Synchronisation 19.1.1.3 OFDM/CDMA 19.1.1.4 Adaptive antennas 19.1.1.5 OFDM applications 19.2 The Frequency Domain Modulation 19.3 OFDM System Performance over AWGN Channels 19.4 Clipping Amplification 19.4.1 OFDM signal amplitude statistics 19.4.2 Clipping amplifier simulations 19.4.2.1 Peak-power reduction techniques 19.4.2.2 BER performance using clipping amplifiers 19.4.2.3 Signal spectrum with clipping amplifier 19.4.3 Clipping amplification - summary 19.5 Analogue-to-Digital Conversion 19.6 Phase Noise 19.6.1 Effects of phase noise 19.6.2 Phase noise simulations 19.6.2.1 White phase noise model 19.6.2.1.1 Serial modem 19.6.2.1.2 OFDM modem 19.6.2.2 Coloured phase noise model 19.6.3 Phase noise - Summary 20 OFDM Transmission over Wideband Channels 20.1 The Channel Model 20.1.1 The wireless asynchronous transfer mode system 20.1.1.1 The WATM channel 20.1.1.2 The shortened WATM channel 20.1.2 The wireless local area network system 20.1.2.1 The WLAN channel 20.1.3 The UMTS system 20.1.3.1 The UMTS type channel 20.2 Effects of Time Dispersive Channels on OFDM 20.2.1 Effects of the stationary time dispersive channel 20.2.2 Non-stationary channel 20.2.2.1 Summary of time-variant channels 20.2.3 Signalling over time dispersive OFDM channels 20.3 Channel Estimation 20.3.1 Frequency domain channel estimation 20.3.1.1 Pilot symbol assisted schemes 20.3.1.1.1 Linear interpolation for PSAM 20.3.1.1.2 Ideal lowpass interpolation for PSAM 20.3.1.1.3 Summary 20.3.2 Time domain channel estimation 20.4 System Performance 20.4.1 Static time dispersive channel 20.4.1.1 Perfect channel estimation 20.4.1.2 Differentially coded modulation 20.4.1.3 Pilot symbol assisted modulation 20.4.2 Slowly varying time-dispersive channel 20.4.2.1 Perfect channel estimation 20.4.2.2 Pilot symbol assisted modulation 20.5 Conclusion 21 Time and Frequency Domain Synchronisation 21.1 Performance with Frequency and Timing Errors 21.1.1 Frequency shift 21.1.1.1 The spectrum of the OFDM signal 21.1.1.2 Effects of frequency mismatch on different modulation schemes 21.1.1.2.1 Coherent modulation 21.1.1.2.2 PSAM 21.1.1.2.3 Differential modulation 21.1.1.2.4 Frequency error - summary 21.1.2 Time domain synchronisation errors 21.1.2.1 Coherent demodulation 21.1.2.2 Pilot symbol assisted modulation 21.1.2.3 Differential modulation 21.1.2.3.1 Time-domain synchronisation errors - summary 21.2 Synchronisation Algorithms 21.2.1 Coarse frame and OFDM symbol synchronisation 21.2.2 Fine symbol tracking 21.2.3 Frequency acquisition 21.2.4 Frequency tracking 21.2.5 Synchronisation by autocorrelation 21.2.6 Multiple Access Frame Structure 21.2.6.1 The reference symbol 21.2.6.2 The correlation functions 21.2.7 Frequency tracking and OFDM symbol synchronisation 21.2.7.1 OFDM symbol synchronisation 21.2.7.2 Frequency tracking 21.2.8 Frequency acquisition and frame synchronisation 21.2.8.1 Frame synchronisation 21.2.8.2 Frequency acquisition 21.2.8.3 Block diagram of the synchronisation algorithms 21.2.9 Synchronisation using pilots 21.2.9.1 The reference symbol 21.2.9.2 Frequency acquisition 21.2.9.3 Performance of the pilot based frequency acquisition in AWGN Channels 21.2.9.4 Alternative frequency error estimation for frequency-domain pilot tones 21.3 Comparison of the Frequency Acquisition Algorithms 21.4 BER Performance with Frequency Synchronisation 21.5 Conclusion 21.6 Appendix: OFDM Synchronisation Performance 21.6.1 Frequency synchronisation in an AWGN channel 21.6.1.1 One phasor in AWGN environment 21.6.1.1.1 Cartesian coordinates 21.6.1.1.2 Polar coordinates 21.6.1.2 Product of two noisy phasors 21.6.1.2.1 Joint probability density 21.6.1.2.2 Phase distribution 21.6.1.2.3 Numerical integration 22 Adaptive Single- and Multi-user OFDM 22.1 Introduction 22.1.1 Motivation 22.1.2 Adaptive techniques 22.1.2.1 Channel quality estimation 22.1.2.2 Parameter adaptation 22.1.2.3 Signalling the parameters 22.1.3 System aspects 22.2 Adaptive Modulation for OFDM 22.2.1 System model 22.2.2 Channel model 22.2.3 Channel estimation 22.2.4 Choice of the modulation modes 22.2.4.1 Fixed threshold adaptation algorithm 22.2.4.2 Sub-band BER estimator adaptation algorithm 22.2.5 Constant throughput adaptive OFDM 22.2.6 Signalling and blind detection 22.2.6.1 Signalling 22.2.6.2 Blind detection by SNR estimation 22.2.6.3 Blind detection by multi-mode trellis decoder 22.2.7 Sub-band adaptive OFDM and channel coding 22.2.8 The effect of channel Doppler frequency 22.2.9 Channel estimation 22.3 Adaptive OFDM Speech System 22.3.1 Introduction 22.3.2 System overview 22.3.2.1 System parameters 22.3.3 Constant throughput adaptive modulation 22.3.3.1 Constant-rate BER performance 22.3.4 Multimode adaptation 22.3.4.1 Mode switching 22.3.5 Simulation results 22.3.5.1 Frame error results 22.3.5.2 Audio segmental SNR 22.4 Pre-equalisation 22.4.1 Motivation 22.4.2 Pre-equalisation with sub-band blocking 22.4.3 Adaptive modulation with spectral predistortion 22.5 Comparison of the Adaptive Techniques 22.6 Near-optimum Power- and Bit-allocation in OFDM 22.6.1 State-of-the-art 22.6.2 Problem description 22.6.3 Power and bit allocation algorithm 22.7 Multi-User AOFDM 22.7.1 Introduction 22.7.2 Adaptive transceiver architecture 22.7.3 Simulation results - perfect channel knowledge 22.7.4 Pilot-based channel parameter estimation 22.8 Summary 23 Block-Coded Adaptive OFDM 23.1 Introduction 23.1.1 Motivation 23.1.2 Choice of error correction codes 23.2 Redundant Residue Number System Codes 23.2.1 Performance in an AWGN channel 23.2.1.1 Performance in a fading time dispersive channel 23.2.1.2 Adaptive RRNS-coded OFDM 23.2.2 ARRNS/AOFDM transceivers 23.2.3 Soft decision RRNS decoding 23.3 Turbo BCH Codes 23.3.1 Adaptive TBCH coding 23.3.2 Joint ATBCH/AOFDM algorithm 23.4 Signalling 23.5 Comparison of Coded Adaptive OFDM Schemes 23.6 Summary, Conclusions and Further OFDM Research 23.6.1 Summary of the OFDM-related chapters 23.6.2 Conclusions concerning the OFDM chapters 23.6.3 Suggestions for further OFDM research 24 QAM-based Video Broadcast Systems 24.1 DVB-T for Mobile Receivers 24.1.1 Background and motivation 24.1.2 DVB terrestrial scheme 24.1.3 Terrestrial broadcast channel model 24.1.4 Non-hierarchical OFDM DVB performance 24.1.5 Video data partitioning scheme 24.1.6 Hierarchical OFDM DVB performance 24.1.7 Conclusions and future work 24.2 Satellite-based Video Broadcasting 24.2.1 Background and motivation 24.2.2 DVB satellite scheme 24.2.3 Satellite channel model 24.2.4 The blind equalisers 24.2.5 Performance of the DVB satellite scheme 24.2.5.1 Transmission over the symbol-spaced two-path 24.2.5.2 Transmission over the two-symbol delay channel 24.2.5.3 Performance summary of the DVB-S system 24.2.6 Conclusions and future work Glossary Bibliography Index Author Index