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MAC Protocols Design for Cooperative Networks

Various techniques such as diversity and channel coding are implemented to mitigate wireless channel impairments and to improve throughput. This may introduce some overhead or the need for multiple antennas and/or transceivers. One different approach to mitigate these issues is cooperative communication. The main objective of cooperative communication is to improve the link quality between nodes with the poor channel condition. Broadcast nature of a wireless transmission helps neighboring nodes from overhearing a transmitted packet. Under poor channel condition between the source and destination (s-d), overheard packets can be relayed through a node having good channel condition with s-d pair. This increases throughput of the entire network and/or reliability of a packet delivery. The node which helps to improve communication quality between s-d pair is known as a helper node.

In its simple implementation, helper nodes just relay the signal from sender to destination boosting data rate and hence channel utilization. Figure 1 illustrates basic functionality of cooperative communication, where communication between two nodes S and D, sender and destination respectively, is boost by multiple helper nodes H1, ....., Hn. In actual situation there may only one helper nodes. Helper nodes here just relay packets from S to D. D on the other hand combine signal from various helper nodes and/or sender S. Helper nodes is choose based on various channel condition between S and D.

Cooperative communication in distributed wireless networks adds new challenged in designing communication protocols. Hence, MAC scheme based on cooperation needs to be carefully designed. Several challenges mentioned in literature as follows:

In this research we focused on developing cooperation based MAC protocol customize for different wireless networking scenarios.

Current Researchers:

Sailesh Bharati, Yong Zhou.