Bi-directional Central-Coordinated Resource-Reserved Multiple Access (CRMA) Scheme Analysis with TCP and UDP Traffic

This paper presents the analysis of a low complexity central-coordinated resource-reserved multiple access (CRMA) medium access control (MAC) protocol for optical wireless communication (OWC) networks. CRMA is a time-division multiplexing based MAC, in which a central controller allocates upstream transmission time-slots to the user nodes. The earlier work on CRMA considers that the user nodes always have a packet to send and have no queues. As a result, depending on channel availability, a small number of users may send a significant number of data packets, showing high throughputs and low latency. However, we take a more practical approach by providing a limited data rate of 10% of the network load to all the network users and introducing queues. We further modify the mathematical model to account for the effects of our assumptions. We compare CRMA performance for TCP and UDP traffic over a noisy channel and investigate the requirement of a suitable error-control mechanism to improve MAC performance.