An active helper searching mechanism for directional cooperative media access control (MAC) protocols

Cooperative communication [1] and directional antenna systems are considered two key technologies for future wireless networks. There are also issues about the combination of these two technologies.[12, 13] Most research in this area needed a table recording the near-by transmission. However, due to the property of passive overhearing, the table may only be partially good for the operation, especially for directional antenna systems. In this paper, we proposed an active helper searching mechanism to improve the completeness of the table. The helper activated its own helpers searching rather than waiting for the overhearing communication from others'. We compared four schemes including the base 802.11g scheme, the D-NoopMAC scheme, the D-CoopMAC scheme with the CoopTable built by conventional methods and the D-CoopMAC scheme with D-CoTable built with our proposed active helper searching mechanism. The simulation results proved that coop-directional MAC schemes with the active helper scheme improved their performance. We also concluded that nodes with directional antenna should be regulated to help those omni-directional nodes to increase the total network throughput. We leaved node mobility issues as the future work.