Comparison of utilization in optical CDMA and WDMA broadcast local-area networks with physical noise

The utilization, defined as the throughput normalized to the time-domain processing gain, is used as metric to compare the performance of optical code-division multiple-access (WDMA) local-area networks. The impact of shot and thermal noise, as well as multiple-access interference (MAI) for the O-CDMA system, is taken into account. We find that a low offered loads or low received power levels, the WDMA system outperforms the O-CDMA system by a wide margin; however, at higher offered loads and when sufficient optical power is available at the receiver, the O-CDMA scheme offers a performance advantage. The results suggest that an adaptive system, able to switch between WDMA and O-CDMA, would make the best use of the fiber-optic channel.