State Estimation in Optical CDMA Networks

State estimation is a mechanism to estimate the state of an optical CDMA network. It can prevent degradation of throughput at high offered load when used as part of Interference Avoidance, a contention media access control protocol for optical CDMA Local Area Networks. Optical CDMA is a multiple access technique for broadcast optical LANs. The throughput of an optical CDMA LAN at high offered load is limited by multiuser interference. Interference Avoidance, prevents throughput degradation at high loads. It consists of state estimation and transmission scheduling. This work proposes algorithms for state estimation and studies the performance of Interference Avoidance under these algorithms. The analysis shows that the performance is sensitive to the state estimation algorithm and its parameters. When used with codesets of long lengths (> 100) and low weight (< 5), state estimation prevents throughput collapse and stabilize throughput at around 30% of the maximum. The throughput of Interference Avoidance with the state estimation algorithms is within 20% of throughput with optimal state estimation.