Throughput-delay performance of interference level-adaptive transmission in voice/data integrated CDMA network with variable spreading gain

The throughput and delay performance of adaptive spreading gain uplink packet transmission in real-time and non-real-time data integrated CDMA networks are analysed under AWGN and Rayleigh fading channels. The processing gain for the non-real-time data is adaptively changed according to the total uplink interference level so that a required signal-to-interference ratio (SIR) can be achieved. The optimum values for the required SIR with regard to maximising the throughput are derived as a function of packet length. The optimised adaptive rate system achieves significantly improved throughput compared to the non-adaptive rate system. In addition, the adaptive rate system achieves almost linear increase in packet delay with traffic density, while the packet delay of the non-adaptive rate system shows an abrupt increase as traffic density increases.