This paper investigates robust transmission of a coded video sequence over unreliable packet networks. A content-based error-resilient coding (CBERC) algorithm is proposed to prevent severe error propagation. Specifically, the CBERC encoder performs motion-compensated prediction by taking the video content into consideration. A criterion based on the worst-case scenario is also provided to determine appropriate CBERC threshold. The CBERC algorithm does not require a feedback channel and supports both point-to-point and multi-point communications. It is of low complexity and is compatible with all the widely accepted video coding standards such as H.263+, H.261, MPEG-1, MPEG-2 and MPEG-4.

A video content based coding algorithm is presented to eliminate the error propagation effects caused by transmitting highly compressed video sequences over unreliable packet networks. We study the criteria to determine an appropriate threshold for it and conduct experiments in a bursty packet loss environment. Promising results are obtained in the preliminary simulations.

This paper investigates the performance of ordered statistics decoding (OSD) of linear block codes with binary differential phase-shift-keying (2DPSK) transmission on frequency nonselective multipath channels. First, the wireless channel is modeled as a frequency nonselective, slow fading environment without intersymbol interference. Second, block interleaving is embedded to decorrelate the successive received symbols so that the performance of OSD, designed essentially for memoryless channels, is retained. Third, we derive the log-likelihood ratio of received symbols based on 2DPSK modulation. Fourth, we derive the statistics of received symbols and the statistics of received symbols after ordering. Further, we analyze the system error performance for sufficient degree of interleaving. Specifically, we derive the asymptotic bit error rate (BER) of OSD at high SNRs using the first-order approximation, finally, we conduct experiments at various channel characteristics and interleaving degrees for (128, 61, 22) extended BCH code and (24, 12, 8) extended Golay code. Results show that the error performance improves tremendously with increased interleaving degree.

This paper investigates the performance of ordered statistics decoding of linear block codes with binary differential phase-shift-keying (2DPSK) transmission on the wide-sense-stationary uncorrelated-scattering (WSSUS) Rayleigh fading channel. For a typical mobile speed of 60 mph, tropospheric scatter radio communication at a carrier frequency of 900 MHz and very low bit rate video communication at a transmission speed of 32 kbit/s, the channel is modeled as a frequency non-selective, slow fading environment without inter-symbol interference (ISI). At a bit error rate (BER) of 10/sup -5/, 34.5 dB and 38 dB gains compared to uncoded 2DPSK are obtained for the decoding of the (24,12,8) extended Golay code and the (128,64,22) extended BCH code with sufficient degree of interleaving.

In this study, error performance analysis and simulation results are provided for the weighted erasure decoding (WED) of binary linear block codes on Q-ary output channel. In particular, the optimum channel quantizer for WED is derived and compared with WED designed based on the cutoff rate criterion, as traditionally proposed. Simulations are conducted for the (64, 42, 8) Reed-Muller (RM) code on 4-ary and 8-ary output channels. For Q=8 and the bit error rate (BER) 10/sup -4/, the WED with optimum quantizer has a 0.65 dB coding gain over the WED with cutoff rate quantizer and a 1.0 dB coding gain over algebraic decoding.

In general, a channel quantizer for a communication system subject to additive white Gaussian noise (AWGN) is designed based on the cutoff rate. This criterion is good if the scheme considered performs close to the theoretical performance corresponding to the cutoff rate, as for error control systems employing convolutional codes. However, it is no longer true for systems using low complexity suboptimum decoding algorithms for block codes. We illustrate this point and present three examples for which we compare the optimum quantizer and the quantizer based on the cutoff rate for Q=4 quantization levels.

Soft-decision decoding of linear block codes for robust H.263 video transmission in a zero-mean, additive white Gaussian noise (AWGN) channel is investigated. We implement an effective error concealment (EC) scheme at the source decoder to reduce the annoying artifacts caused by decoding a corrupted bit stream. To alleviate the spatial and temporal error propagation, an error prevention (EP) strategy is introduced at the H.263 encoder. Simulation results show that a large portion of the peak signal-to-noise ratio (PSNR) gain is obtained by ordered statistics decoding of the received sequence. Furthermore, the residual channel coding errors are concealed and compensated by realizing the proposed EC and EP schemes.