Allocating codes with coding scheme jointly to improve the system throughput of OVSF-CDMA systems

In this paper the error-control coding scheme is considered jointly with codes allocation in OVSF-CDMA systems. In CDMA systems, the multiple access interference limits the number of active users and their transmission rates, which in turn limit the system throughput. The resource has low utilization in most time. The error-control coding scheme can correct some transmission errors at the cost of low coding efficiency. Coding scheme tolerates the multiple access interference even when more users are active. With a proper combination of coding scheme and codes allocation, it is possible to admit more users and to achieve higher system throughput. A traffic scheduling algorithm based on this joint design scheme is proposed for constant rate services in OVSF-CDMA systems. In simulation we compare the system throughput of our joint design algorithm with those of two conventional algorithms, the algorithm adapting the codes allocation only and the algorithm adapting the coding scheme only. It shows the joint design algorithm achieves the highest system throughput