Throughput analysis of turbo-coded CDMA packet communication systems

We analyze the system capacity of turbo coded CDMA packet system with hybrid FEC/ARQ scheme. In particular, assuming the use of punctured turbo codes, we investigate the system capacity in terms of the number of users that can be supported by the given rate of punctured turbo codes in both the AWGN and multipath fading channel. For a multipath fading channel, we derive a simple closed form expression for the PDF of signal to noise plus interference ratio (SNIR) at the output of matched filter receiver. Then, using an improved union bound, we evaluate the codeword error probabilities and the corresponding throughput performance for various rates of punctured turbo codes. With these results, we obtain the CDMA system capacity and compare its performance with theoretical capacity bounds obtained with idealized packet communication systems in which packet overheads, transmission and decoding delay can be ignored.