Optimization of Channel Capacity of Multi-Rate Multi-Code CDMA for Broadband Packet Wireless Access

This paper presents a mathematical technique for determining the optimum packet size in multi-rate multi-code Code Division Multiple Access (CDMA) network. This scheme optimizes the channel capacity and tries to meet the multi-rate transmission demands of all the users by varying the size of packets. Throughput is defined as the expected value of the total number of successful transmitted packets/slot. The Analysis shows that as we increase the size of packets keeping processing gain, error detection and correction capability (t) of the network fixed, throughput drops with increase in the number of transmitted packets/slot. It is found that channel capacity for packet length L = 64, 128, 256, 512 and 1,024 in terms of throughput are 120, 72, 50, 38, 30 for t = 10, respectively, and are 420, 140, 79, 50 and 38 for t = 20, respectively. It is concluded that to optimize the channel capacity, we have to transmit possible large size packets as per the flow control of the network