Performance Evaluation of RCPT Hybrid ARQ Schemes for DS-CDMA Mobile Radio over Frequency Selective Rayleigh Fading Channel

In this paper, we evaluate by computer simulations the throughput performance of the turbo-coded hybrid ARQ for direct sequence code division multiple access (DS-CDMA) with antenna diversity reception and Rake combining in a frequency selective Rayleigh fading channel. The effect of a range of system parameters and propagation parameters (viz., the frame length, puncturing rate, spreading factor, number of diversity antennas, fading rate, and the power delay profile of the multipath channel (number of paths and profile shape)) is investigated. It is found that the rate compatible punctured turbo (RCPT) coded hybrid ARQ system has the highest throughput when minimum amount of redundancy bits is transmitted with each retransmission and that the throughput is almost independent of the frame length and the fading rate. It is also found that smaller spreading factor for a given chip rate gives a higher throughput in bits/sec.