On The Hybrid Arq Scheme With Code Combining And The Related Problems

High speed packet data transmission with high reliability is the most promising direction for the future wireless communications. In order to gurantee reliable transmission, various error contol schemes including the forward error correction (FEC) and the hybrid ARQ mechanism, are essential. To improve receiver performance, both space diversity in the multipath environment and time diversity, such as code combining in the hybrid ARQ, should normally be employed. Besides, the implementation of a hybrid error correction control scheme is heavily dependent on the proper channel estimation algorithm. Therefore, in this thesis, focusing on various hybrid error control schemes for wireless packet-oriented communication system, the following issues are addressed, hybrid ARQ scheme and its performance enhancement owing to the code combining employed, the performance analysis of equal-gain-combining (EGC) diversity reception, the high-speed parallel Turbo coding scheme, and SNR estimation algorithm based on redundant repetition information.At first, the performance evaluation of hybrid ARQ with code combining in packet-oriented CDMA system is investigated. By extending Pursley's signal-to-interference plus noise ratio (SINR) analysis to hybrid ARQ with code combining in packet-oriented CDMA system, an extended SINR formula is derived, which describes explicitly the SINR variation of the code symbol involved in code combining. Moreover, it is shown that the effective SINR of the combined symbol is increased by a coefficient which is proportional to the number of repeated replicas involved in the code combining. Based on the extended SINR formula and the resultant SINR variation, a quasi-analytical approximation method is proposed for the performance evaluation of hybrid ARQ with code combining. It is validated that the quasi-analytical approximation offers a simplified routine to' estimate the performance of hybrid ARQ with code combining, particularly for the applications whose reliability performance of the FEC counterpart could be numerically calculated or evaluated through simulation.Thereafter, the thesis focuses on the performance analysis of hybrid ARQ with diversity combining on the ideally interleaved flat Rayleigh fading channel, which is known as a frustrated problem due to the difficulty in solving the multiple-foldintegration involved. A novel analysis method, i.e., the approximate variable is proposed to simplify the analysis, wherein the involved cross-product of two random variables is substituted with the approximate sum of the power of two random variables. Both the lower and upper bounds are derived, approximate analysis method is also proposed for evaluating the performance of hybrid ARQ with diversity combining on the ideally interleaved flat Rayleigh fading channel. It is disclosed that the diversity combining contributes to an increase in the diversity order on the ideally interleaved flat Rayleigh fading channel, which is approximately proportional to the number of repeated copies involved.Next, the thesis moves its attention to the type III hybrid ARQ with code combining. The code combining in type III hybrid ARQ becomes more complicated due to the variation of the combined codeword. And the combined puncturing pattern is proposed to illuminate the involved composite code combining. By extending the analysis to the convolutional codes whose symbols exhibit different effective signal-to-noise ratio owing to the composite code combining, a closed form of the residual pairwise error probability of the combined RCPC codes is derived for the AWGN channel. Based on the combined puncturing patterns and the accumulate SINR effect, upper and lower bounds on the error performance are derived, together with an approximation method which is shown to be quite satisfactory by numerical and simulation results. By extending the analysis to the convolutional codes whose symbols experience fading path with different fading power gain due to the composite code combining, a closed form of the residual pairwise...