Simulation and improvements for cooperative MAC (COMAC) protocol

Official URL: http://192.168.1.20/record=b1378202 (Table of Contents)

Cooperative communication has been recently proposed for wireless sensor networks for achieving reliable, high data rate communication, eventually decreasing energy consumption at the nodes and extending the lifetime of the sensor network. The benefits of cooperation can be obtained by appropriate design of the medium access control (MAC) protocol. In this thesis, we present a cooperative MAC protocol that enables cooperation of multiple relays in a distributed fashion. It is shown that energy efficiency of the protocol significantly depends on cooperator selection and power assignment. We propose random and intelligent timer models for coordinating access of the cooperating nodes. Next, we consider the contention channel observed during the cooperator selection period and we propose a collision resolution mechanism. We consider two alternatives for cooperative transmissions, and compare the performances of code division based and time division based approaches. The cooperative MAC protocol is further improved by introducing sleep feature for the relay nodes, since the major sources of wasted energy for the cooperative system are idle listening and overhearing. We evaluate the cooperative MAC protocol with all the proposed enhancements in terms of energy efficiency, throughput, average delay and MAC overhead cost and demonstrate the performance improvements.