Performance Optimization of Digital Communications Systems examines particular optimization problems in digital communications, presenting analytical techniques in combination with SystemView and MATLAB® simulations.

Features:

• Provides analytical and simulation approaches to performance optimization in digital networks
• Examines the estimation of the signal-to-noise ratio (SNR) of a communications channel in a complex multipath propagation environment
• Reviews a method of pulse shaping: the generation of low-complexity, spectrally efficient pulses for digital communications
• Presents a general methodology for optimal selection of the automatic repeat request (ARQ) parameters in quadrature amplitude modulation channels
• Analyzes the performance optimization of multicarrier systems with forward error correction and ARQ
• Discusses the estimation of the bit error rate of self-similar constellations in ADSL systems
• Develops an exact solution for the throughput of a general duplex communications channel with forward error correction and ARQ
• Details how to break a TCP/IP message into MAC packets in networks compliant with the IEEE 802.11 wireless LAN standard

Contents

Method for Determining the Quality of a Communication Channel

• Main Idea Illustrated and a Minimization Principle
• Phase-Spanning Nyquist Set Test
• Frequency-Spanning Nyquist Set Test
• Determining the Noise Level in a Nonbaseband System
• Measuring the Level of a Useful Signal

Digital Communications in Stealth Mode

• Stealth Communications Transceiver
• Test on Randomness
• BER Performance
• Using a Decoy Signal

Pulse Shape Optimization

• Pulse Shape Optimization Criterion
• SO-Pulse and L-Pulse
• Phi-Pulse
• BER Test
• Approximation of Pulses by SAS
• Data Windows Corresponding to the Pulses Introduced
• Raised Pulses

Optimal Phase Shifters for Peak-to-Average Power Ratio

• Reduction in Multicarrier Communication Systems
• Optimal Phase Shifters and the Constant Envelope Principle
• Flat Spectrum Chirps
• Simulations of Multicarrier Transmission
• Possible Applications of FSC

Optimization of the Automatic Repeat Request Parameters in Quadrature Amplitude Modulation Channels Derivation of the BER of a QAM Channel with FEC and ARQ

• ARQ Performance Gain
• A Method of Estimating the ARQ Gain
• A Procedure for Determining the Optimum ARQ Parameters
• Extension of the Method for the Case of a Slowly Fading Channel
• Determining the Average Number of Transmissions and the
• Uncoded SER, Given the SER Past FEC/ARQ
• Determining an Average Fraction of Erroneous Bits in an Erroneous QAM Symbol

Optimal Selection of Error Correction and Retransmission Parameters in Multichannel Communications Systems

• Performance Gain Due to FEC/ARQ in Discrete Multitone Systems
• Mean-Field Approximation for Multicarrier Channel with ARQ
• An Approximate Solution of Equation 7.2.2
• Optimization of FEC and ARQ Parameters for Current ADSL Standards

Bit Error Rate of Self-Similar Constellations in ADSL Systems

• Self-Similarity of ADSL QAM Constellations
• Error Probability Function of an ADSL QAM Constellation Encoder
• Nonsquare Constellations: An Asymptotic Analysis
• Comparison with Numerical Simulations

Throughput Optimization in a General Duplex Communications System with FEC and ARQ

• A System Model with FEC and ARQ
• Joint Optimization of FEC and ARQ Parameters in Both Directions

A Quantitative Procedure of Optimizing the MAC Packet Size in TCP/IP-Compliant Networks

• Statement of the Problem of Optimizing the MAC Packet Size in TCP/IP-Compliant Networks
• Derivation of Equation 10.2.6
• Determining the Optimal MAC Packet Size in the Case of a
• Variable MAC Frame Length
• Solution to the Problem and Decision Diagrams
• Extension of the Method in the Case of a Fixed MAC Frame Length
• Extension of the Method to Account for Error Detection and Retransmission in the TCP/IP Protocol

Index

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