Performance of the packet scheduling schemes in DS/CDMA systems

In this paper, we investigate two packet scheduling schemes over the downlink of DS/CDMA systems to support packet data services. These schemes are the code division multiplexing (CDX)-based packet scheduling and the time division multiplexing (TDX)-based packet scheduling. To evaluate each scheme more effectively, we derive the throughput gain of the downlink as a performance measure based on the power constraint equation. As the downlink capacity is quite related to the orthogonality factor, our analysis shows from the results that the throughput gain is highly dependent on this factor. Furthermore, it is shown that the TDX scheduling scheme in CDMA downlink affords better performances than the CDX scheduling scheme, except when the orthogonality factor is around 1.