Co-operative Communication : Cross-layer Approach

Abstract

Exploding demand for a growing number of wireless applications has fueled significant development of wireless networks, especially several generations of cellular voice and data networks and, more recently, ad-hoc data networks for wireless computer, home, and personal networking. To overcome the problems wireless medium (fad- ing,interference,etc.), MIMO system can be used but due to size, cost, or hardware limitations, a wireless node may not be able to support multiple transmit antennas. So, the cooperative communication can be used as an alternative to MIMO. Due to the broadcast nature of wireless signals, a wireless transmission intended for a particular destination station can be overheard by other neighboring stations. A focus in cooperative communications is to achieve spatial diversity gains by requiring these neighboring stations to retransmit the overheard information to the nal destination. Layered protocol design provides reasonable performance in wired networks, where individual layer dynamics are limited and the system bandwidth and power are relatively unconstrained. However, it may not be efficient for wireless networks, since the large random dynamics in the wireless link strongly affect performance and design of Network layer protocols. In this dissertation, We have discussed CoopMAC, Cross-layer Protocol used for Cooperative Communication. In CoopMAC Protocol, high data rate stations assist low data rate stations in their transmission by forwarding their tra c. The CoopMAC protocol is simple and backward compatible with the legacy IEEE 802.11 system. An event driven simulator is developed and performance evaluation is carried out in terms of throoughput and delay. The performance is evaluated considering di erent network scenario for IEEE 802.11 and cooopMAC protocol and a comparison between them is presented. The CoopMAC protocol performs better than its legacy IEEE 802.11 in terms of throughput and delay and achieves higher spatial diversity.