Throughput Analysis for Code Division Multiple Accessing of the Spread Spectrum Channel

We consider the use of error correction codes of rate on top of pseudonoise (PN) sequence coding for code division multiple accessing of the spread spectrum channel. The channel is found to have a maximum throughput of 0.72 and 0.36 based on the evaluation of channel capacity and cutoff rate, respectively. More generally, these two values are derived for given bandwidth expanding versus where is the length of the PN sequence and is the number of simultaneous users. It is found that to achieve the maximum throughput, should be small. This implies that coding schemes with short PN sequences and low rate codes are superior in terms of throughput or antijam capability. The extreme case of corresponds to using a very low rate code with no PN sequence coding. Convolutional codes are recommended and analyzed for their error rate and decoding complexity.