CDMA Systems Engineering Handbook

Transcription

1 CDMA Systems Engineering Handbook Jhong Sam Lee Leonard E. Miller Artech House Boston London

2 Table of Contents Preface xix CHAPTER 1: INTRODUCTION AND REVIEW OF SYSTEMS ANALYSIS BASICS Introduction Multiple Access Techniques Spread-Spectrum Techniques IS-95 System Capacity Issues Categories of Spread-Spectrum Systems So, What Is CDMA? Battle of Jamming Power Versus Processing Gain Review of Linear Systems Analysis Fundamentals Linear Systems Finite Impulse Response Filter Fourier Series Trigonometric and Exponential Fourier Series Fourier Transform of a Periodic Function Sampling Theorems Sampling Theorem in the Frequency Domain Sampling Theorem in the Time Domain Sampling Theorem for Bandpass Waveforms Discrete Time Filtering Baseband Pulse Shaping for Bandlimited Transmission Bandlimited Waveforms for Digital Applications FIR Pulse Shaping in IS Probability Functions Probabilities Probability Distribution Functions Characteristic Function Moment Generating Function Correlation Functions and Power Spectra Central Limit Theorem Chernoff Bounds The Narrowband Gaussian Random Process Rayleigh Distributions Rayleigh Fading 118 VII

3 viii CDMA Systems Engineering Handbook Sinewave Plus Narrowband Gaussian Random Process Modeling and Simulation of Bandpass Noise Chi-Squared Distributions Central Chi-Squared Distribution Noncentral Chi-Squared Distribution Lognormal Distributions Probability Density Function of a Lognormal RV Moments of Lognormal RVs 153 References 154 Appendix 1A Impulse Response of Ideal Filter #2 158 Appendix IB Integral of sine Function 159 Appendix 1C Impulse Response RC Filter 160 Appendix ID Probability for a Difference of Chi-Squared RVs 161 CHAPTER 2: MOBILE RADIO PROPAGATION CONSIDERATIONS Overview of Propagation Theory and Models Free-Space Propagation Radio Horizon and Propagation Modes Effect of the Atmosphere Characterization of Terrain and Its Effects Propagation Modes LOS and Diffraction Propagation Modes Propagation in the LOS Region Diffraction Over Terrain and Buildings Empirical Propagation Formulas Hata and CCIR Formulas Walfisch-Ikegami Formula Computer Propagation Loss Models The Longley-Rice and TIREM Models Comparison of WIM and Longley-Rice The Use of Propagation Models in Cellular Design Numerical Example of a Propagation Loss Contour Coverage Area Versus Maximum Tolerable Propagation Loss The Mobile Radio Environment Channel Models Delay-Spread Function 216

4 Table of Contents Frequency Transfer Function Doppler-Spread Function Combined Delay Spread and Doppler Spread Fading and Fade Rate Characterization of the Random Fading Channel Commonly Used Fading Terms Fade Rate and Vehicular Speed Lognormal Shadowing 247 References 248 Appendix 2A Details of Propagation Loss For Irregular Terrain 251 2A.1 Angles of Elevation 251 2A.2 LOS Path Loss 253 2A.3 Diffraction Loss 254 Appendix 2B Derivation of Fade Rate and Duration Formulas 256 CHAPTER 3: BASIC CELLULAR SYSTEMS ENGINEERING Review of Telephone Traffic Theory Telephone Connectivity Traffic Load and Trunk Size Erlang B Statistics The Cellular Concept Expansion of Mobile System Capacity Through Frequency Reuse Cell Geometry Cellular Coordinate Systems Clusters of Hexagonal Cells Locations of Interfering Cells Selection of Cluster Size Interference Ratio Versus Cluster Size Tradeoff of Interference Ratio and Spectral Efficiency Cell Splitting and Base Station Power AMPS Parameters Coverage and Capacity in Cellular Systems Coverage Limits Generic Cellular System Link Budget Receiver Noise Calculation Maximum Tolerable Propagation Loss Coverage Versus Capacity 305

5 CDMA Systems Engineering Handbook Link Margin for the Coverage-Limited Case Determination of Multicell Margin Requirements Reverse Link C/I and C/N as Functions of System Loading System Coverage Versus Traffic Load 321 References 328 Appendix 3A Demonstration That the Form of Pk Satifies the Equations 329 Appendix 3B Moments for the Erlang B Distribution 330 Appendix 3C Summary of Blocking Formulas 331 CHAPTER 4: OVERVIEW OF THE IS-95 STANDARD Coordination of Frequency and Time Cellular Frequency Bands and Channels System Time Description of Forward Link Operations Forward Link CAI Summary Orthogonal Multiplexing Scheme Forward Link Channels Pilot Channel and Quadrature PN Codes Synchronization Channel Paging Channels Traffic Channels Description of Reverse Link Operations Reverse Link CAI Summary Multiple Access Scheme Reverse Link Channels Access Channel Reverse Traffic Channel Comparison of Forward and Reverse Links Special Features of the IS-95 System Power Control Open-Loop Power Control Closed-Loop Power Control Forward Link Power Control Interleaving Techniques Diversity and Handoff 388 References 397 Appendix 4A Theory of Interleaving 398

6 Table of Contents 4A.1 Block Interleaving 398 4A.2 Convolutional Interleaving 399 4A.3 Comparison of Block and Convolutional Interleaving 404 4A.4 Interleaver Design Appendix 4B Hash Function Used in IS B.1 Review of the Golden Ratio and Fibonacci Numbers 409 4B.2 Hash Function Example 411 4B.3 The IS-95 Hash Function 414 4B.4 IS-95 Random Number Generator 418 CHAPTER 5: WALSH FUNCTIONS AND CRC CODES Definition of the Walsh Functions Walsh Sequence Specifications (Instant Walsh Functions) Walsh Function Generation Walsh Function Generation Using Rademacher Functions Walsh Function Generation Using Hadamard Matrices Finite Fields Vector Spaces Walsh Function Generation Using Basis Vectors Orthogonal Walsh Functions for CDMA Applications Walsh Functions Used in the Forward Link Walsh Functions Used in the Reverse Link Walsh Function Decoding Correlation Decoding Fast Walsh Transform Decoding IS-95 Data Frames Linear Block Codes Parity Check Matrix Concept of Syndrome and Error Detection Hamming Codes Cyclic Codes Systematic Cyclic Codes Encoders for Cyclic Codes Syndrome Calculation by Shift Register Circuits for Error Detection Binary BCH Codes Frame and Message Structure Quality Indicators CRC Computations for the Forward Link Channels CRC Computations for the Reverse Link Channels 538

7 xii CDMA Systems Engineering Handbook References 540 CHAPTER 6: THEORY AND APPLICATION OF PSEUDONOISE SEQUENCES Properties of Pseudonoise Sequences Extension Galois Fields and Primitive Polynomials Roots of Primitive Polynomials and Maximal-Length Sequences Reciprocal Polynomials ^ and Tables of Irreducible Polynomials Mechanization of Linear Feedback Shift Registers for Binary Irreducible Primitive Polynomials State Vector Variations for PN Sequence Phase Shifts Shift Register Implementation of PN Sequences Shift Register Generators With Special Loading Vectors Derivation of Sequences at the MSRG Outputs The Use of Masks To Select a Sequence Phase Shift Relationship Between the Mask and the Sequence Shift for Arbitrary Shift Register Loading Five-Stage MSRG Example PN Sequences Specified in IS Example Short PN Code Masks Autocorrelation and Cross-Correlation Properties of Binary Sequences Correlation Function for Real-Time Signals Partial Correlation Functions of PN Sequences Spectral Properties of Binary Sequence Waveforms Operations on Maximal-Length Sequences Orthogonalization Decimation of PN Sequences Gold Codes The Cross-Correlation Problem Gold Codes and GPS Signal Structure 663 References 665 Appendix 6A Inductive Proof of the Fact That g(x) = s*(x) 666 Appendix 6B Computer Programs 668 6B.1 Program for Computing the Shift K 668 6B.2 Program for Computing x^modulo f(x) 669 6B.3 Program for Computing Long PN Code Transition Matrix Appendix 6C Proof of Correlation Function Theorem 672

8 Table of Contents xiii Appendix 6D Extension of Correlation Theorem to Bandlimited Pulses 673 CHAPTER 7: MODULATION AND DEMODULATION OF IS-95 SPREAD-SPECTRUM SIGNALS Likelihood Function Vector Representation of the Waveforms Optimal Receiver Principles for Gaussian Channels Correlation Receivers Matched Filter Receivers Performance Evaluations for M-ary Communications in AWGN Union Bound on the Probability of Error of M-ary Communications Systems Modulation Schemes Used in the IS-95 System Forward Link Error Performance of Forward Link Channel Symbols in AWGN Error Performance of Forward Link Channel Symbols in Rayleigh Fading Reverse Link Noncoherent Signal Processing Envelope Detection Receiver for M-ary Communications System Noncoherent Binary Orthogonal System Noncoherent Binary Orthogonal System in Rayleigh Fading IS-95 CDMA Reverse Link M-ary Orthogonal Modulation Scheme Optimal Demodulation for IS-95 Reverse Link Waveforms Reverse Link Performance in Rayleigh Fading QPSK Versus BPSK Analysis of a BPSK CDMA System Analysis of a QPSK CDMA System Comparison of BPSK, QPSK Variances PN Code Acquisition and Tracking Review of Correlation Operations Initial Sequence Phase Acquisition Code Tracking With a Delay-Lock Loop 790

9 xiv CDMA Systems Engineering Handbook Full-Time Noncoherent DLL Tracking Full-Time Coherent DLL Tracking TDL Tracking Shaped Versus Unshaped PN Sequences for Despreading Analysis of the Effect of Pulse Shape at the Receiver Simulated Comparison of the Energies Accumulated 810 References 814 Appendix 7A The Gram-Schmidt Orthogonalization Procedure 816 Appendix 7B Average of BPSK Error Probability 822 Appendix 7C Parameters of Integrated White Noise 823 Appendix 7D Details of BPSK and QPSK Variances 827 Appendix 7E Acquisition Decision Noise Terms 834 CHAPTER 8: CONVOLUTIONAL CODES AND THEIR USE IN IS Introduction Convolutional Codes Convolutional Encoders Encoder Connection Vector Representation Encoder Impulse Response Representation Polynomial Representation of the Encoder State Representation of the Encoder Tree Diagram for a Convolutional Encoder Trellis Diagram for a Convolutional Encoder Maximum Likelihood Decoding of Convolutional Codes Minimum Hamming Distance Decoding Rule Viterbi Decoding Algorithm Distance Properties of Convolutional Codes Transfer Functions of Convolutional Codes Systematic and Nonsystematic Convolutional Codes Catastrophic Error Propagation in Convolutional Codes 8.4 Performance Bounds for Viterbi Decoding of Convolutional Codes Probability of Error Bounds for Hard Decision Decoding Bit-Error Probability for the BSC Probability of Error Bounds for Soft-Decision Decoding Bit-Error Probability Bounds for Soft-Decision Viterbi Decoding Estimates of Coding Gains of Convolutional Codes Convolutional Codes Used in the IS-95 CDMA System 906

10 Table of Contents xv Performance of the Convolutional Codes Used in the IS-95 System Coding Gains Versus Constraint Length Quantization of the Received Signal 916 References 922 Selected Bibliography 924 Appendix 8A Proof of Q-Function Inequality 925 CHAPTER 9: DIVERSITY TECHNIQUES AND RAKE PROCESSING Introduction Diversity Techniques Diversity Selection and Combining Techniques Selection Diversity Noncoherent M-ary Frequency-Shift Keying (NCMFSK) Noncoherent Binary Frequency-Shift Keying (NCBFSK) BPSK Modulation TT/4 DQPSK Modulation System With Differential Detection Equal Gain Diversity Combining M-ary Noncoherent Orthogonal Modulation System MFSK With Rayleigh Fading BPSK Modulation Under L-fold Diversity With EGC Reception TT/4 DQPSK Modulation With Differential Detection Under L -f old Diversity With EGC Reception Noncoherent Binary Orthogonal System and Optimal Diversity Maximal Ratio Combining Diversity Reception Optimality Proof of MRC Diversity Reception Example of MRC The Rake Receiver Concept Basics of Rake Receiver Design The Essence of Price and Green's Rake Concept The Use of the Rake Concept in IS References 982

11 xvi CDMA Systems Engineering Handbook Selected Bibliography 984 Appendix 9A Derivation of M-ary Orthogonal Diversity Performances A.1 Selection Diversity 987 9A.2 EGC Diversity Reception 988 Appendix 9B Derivation of BPSK Diversity Performances 992 9B.1 Selection Diversity 992 9B.2 EGC Diversity Reception 993 Appendix 9C Derivation of TT/4 DQPSK Diversity Performances 997 9C.1 Selection Diversity Performance 997 9C.2 EGC Diversity Reception 999 CHAPTER 10: CDMA CELLULAR SYSTEM DESIGN AND ERLANG CAPACITY CDMA Cells Forward Link Cochannel Interference Same-Cell Interference Other-Cell Interference Reverse Link Cochannel Interference Same-Cell Interference Other-Cell Interference CDMA Reuse Parameters CDMA Capacity Revisited CDMA Cell Loading Cell Size Maximum Propagation Loss and the Cell Radius Forward Link Power Budget Reverse Link Power Budget Link Balancing CDMA Link Reliability and Erlang Capacity Link Reliability and Link Margin Link Margin for No Interference Link Margin and Power Control Margin Required With Interference Margin for Diversity Reception and Soft Handoff Reliable Signal Level Erlang Capacity Formulation of the Blocking Probability Mean and Variance of Z CDMA Blocking Probability Formula

12 Table of Contents xvii for Gaussian Assumptions CDMA Blocking Probability Formula for Lognormal Assumptions Comparison of CDMA Blocking Probabilities Erlang Capacity Comparisons of CDMA, FDMA, andtdma Number of Subscribers During the Busy Hour CDMA Area Coverage Analysis Required Received Signal Level as a Function of Loading Cell Radius as a Function of Cell Loading Base Station Density 1094 References 1103 Appendix 10A Analysis of Second-Order Reuse Fraction 1107 CHAPTER 11: CDMA OPTIMIZATION ISSUES Selection of Pilot PN Code Offsets The Role of PN Offsets in System Operation Pilot Offset Search Parameters Effect of Multipath on Search Window Bounds on Relative Delays IS-95 Search Window Parameters Selection of Offset Spacing Optimal Allocation of CDMA Forward Link Power Forward Link Channel SNR Requirements Pilot Channel Sync Channel Paging Channels Traffic Channels Interference and Noise Terms Total Forward Link Power Forward Link Power Control Factor Net Losses on the Forward Link Solution for Forward Link Powers Allocated Channel Power as a Fraction of Total Power Parametric Variations in the Power Solutions Selection of Forward Link Fade Margins Limits on Receiver Margin 1153

13 xviii CDMA Systems Engineering Handbook Receiver and Transmitter Powers Under No Interference Receiver and Transmitter Powers When There Is Interference Numerical Examples of CDMA Margin Receiver Margin Versus Transmitter Margin Receiver Margin Versus Total Forward Link Power Forward and Reverse Link Capacity Balancing Forward Link Capacity Asymptotic Forward Link Capacity Power-Limited Forward Link Capacity Capacity Balancing Implementation of Forward Link Dynamic Power Allocation 1178 References 1186 About the Authors 1187 Index 1189