Interference Avoidance in Optical Code Division Multiple Access

Abstract

This dissertation proposes a contention media access control protocol for optical Code Division Multiple Access (CDMA) Local Area Networks (LANs) with Interference Avoidance. Optical CDMA is spread spectrum technology for multiplexing transmissions on an optical fiber. When OCDMA used as the physical layer in Local Area Networks, its throughput tends to zero at high offered load because of multiuser interference. Interference Avoidance prevents this throughput collapse of optical CDMA networks at high offered load. It extends the Carrier Sensing mechanism to high speed, shared medium, optical networks. Interference Avoidance consists of transmission scheduling. This work proposes algorithms for transmission scheduling using Fixed-rate perfect code and Variable-rate perfect code. The transmission scheduling algorithms stabilize the throughput at around 25% for fixed rate and 36% for variable rate of the maximum at high offered load. The work compares two algorithms with ALOHA CDMA where all transitions are admissible, in addition to that the throughput of aloha is around 18%. The strategy of this project is to get mathematical representation of transmission scheduling and solve its equation using MATLB program.