xiv Contents 13.4 Good Codes Based on Combination of Simple Codes 725 13.4.1 Product Codes.727 13.4.2 Concatenated Codes,728 13.5 Turbo Codes and Iterative Decoding 728 13.5.1 MAP Decoding of Convolutional Codes-The BCJR Algorithm,731 13.5.2 Iterative Decoding for Turbo Codes,737 13.5.3 Performance of Turbo Codes,739 13.6 Low-Density Parity-Check Codes 741 13.6.1 Decoding LDPC Codes,745 13.7 Coding for Bandwidth-Constrained Channels 747 13.7.1 Combined Coding and Modulation,748 13.7.2 Trellis-Coded Modulation,749 13.8 Practical Applications of Coding 756 13.8.1 Coding for Deep-Space Communications,756 13.8.2 Coding for Telephone-Line Modems,758 13.9 Summary and Further Reading 759 Problems 760 14 DATA TRANSMISSION IN FADING MULTIPATH CHANNELS 769 14.1 Characterization of Physical Wireless Channels 769 14.2 Channel Models for Time-Variant Multipath Channels 771 14.2.1 Frequency Nonselective Fading Channel,774 14.2.2 Frequency Selective Fading Channel,777 14.2.3 Models for the Doppler Power Spectrum,778 14.2.4 Propagation Models for Mobile Radio Channels,781 14.3 Performance of Binary Modulation in Rayleigh Fading Channels 783 14.3.1 Probability of Error in Frequency Nonselective Channels,783 14.3.2 Performance Improvement through Signal Diversity,786 14.3.3 The RAKE Demodulator and Its Performance in Frequency Selective Channels,792 14.3.4 OFDM Signals in Frequency Selective Channels,794 14.4 Multiple Antenna Systems 795 14.4.1 Channel Models for Multiple Antenna Systems,796 14.4.2 Signal Transmission in a Slow Fading Frequency Nonselective MIMO Channel,797 14.4.3 Detection of Data Symbols in a MIMO System,799 14.4.4 Error Rate Performance of the Detectors,800 14.4.5 Space-Time Codes for MIMO Systems,802 14.5 Link Budget Analysis for Radio Channels 810 14.6 Summary and Further Reading 813 Problems 815xiv Contents 13.4 Good Codes Based on Combination of Simple Codes 725 13.4.1 Product Codes. 727 13.4.2 Concatenated Codes, 728 13.5 Turbo Codes and Iterative Decoding 728 13.5.I MAP Decoding of Convolutional Codes-The BCJR Algorithm, 731 13.5.2 Iterative Decoding for Turbo Codes, 737 13.5.3 Pe1formance of Turbo Codes, 739 13.6 Low-Density Parity-Check Codes 741 13.6.I Decoding LDPC Codes, 745 13.7 Coding for Bandwidth-Constrained Channels 747 13. 7.1 Combined Coding and Modulation, 748 13. 7.2 Trellis-Coded Modulation, 749 13.8 Practical Applications of Coding 756 13.8.I Coding for Deep-Space Communications, 756 13.8.2 Coding for Telephone-Line Modems, 758 13.9 Summary and Further Reading 759 Problems 760 14 DATA TRANSMISSION IN FADING MULTIPATH CHANNELS 14. l Characterization of Physical Wireless Channels 769 14.2 Channel Models for Time-Variant Multipath Channels 771 14.2.1 Frequency Nonselective Fading Channel, 774 14.2.2 Frequency Selective Fading Channel, 777 14.2.3 Models for the Doppler Power Spectrum, 778 14.2.4 Propagation Models for Mobile Radio Channels, 781 14.3 Performance of Binary Modulation in Rayleigh Fading Channels 783 14.3.1 Probability of Error in Frequency Nonselective Channels, 783 14.3.2 Peiformance improvement through Signal Diversity, 786 14.3.3 The RAKE Demodulator and Its Pe1formance in Frequency Selective Channels, 792 14.3.4 OFDM Signals in Frequency Selective Channels, 794 14.4 Multiple Antenna Systems 795 14.4.1 Channel Models for Multiple Antenna Systems, 796 14.4.2 Signal Transmission in a Slow Fading Frequency Nonselective MIMO Channel, 797 14.4.3 Detection of Data Symbols in a MlMO System, 799 14.4.4 Error Rate Peiformance of the Detectors, 800 14.4.5 Space-Time Codes for MIMO Systems, 802 14.5 Link Budget Analysis for Radio Channels 810 14.6 Summary and Further Reading 813 Problems 815 769