Design and analysis of coordinated access schemes for code-limited optical-CDMA networks

This paper investigates code assignment and transmission scheduling schemes for code-limited optical code division multiple access (O-CDMA) networks, where the number of nodes exceeds the number of codes. We present an architectural design of a coordinated access scheme based on a centralized gated-polling controller, and evaluate its performance in terms of scheduling delays and achievable throughputs. In particular, this paper proposes a list-scheduling algorithm for code assignment and analyzes its near-optimal performance. With theoretic analyses and simulations, we derive the relationships among system capacity, traffic load, and network performance, and establish an analytical framework to address practical issues regarding O-CDMA network planning. Performance results indicate that the code-limited system can achieve high throughputs at the expense of scheduling delays. The capacity requirement of the control channel is also investigated to ensure system stability. These results provide an in-depth insight into network dynamics of code-limited systems and can serve as guidelines for network planning and algorithm design.