Cooperation or Not in Mobile Ad Hoc Networks: A MAC Perspective

In this paper, we investigate benefits of cooperative communication in mobile ad hoc networks (MANETs). Cooperative communication as an effective way to mitigate channel impairments has attracted much attention, especially on the physical layer. However, without properly designed higher- layer protocols, the cooperation gain can decrease and even disappear, due to factors such as limited payload and nonnegligible overhead. A two-hop interference model from a medium access control (MAC) point of view is proposed to study the performance of a cooperative network. Analysis based on the model demonstrates that cooperation may not be beneficial when the number of blocked nodes increases. Further, a busy- tone based cooperative MAC scheme is presented to investigate the gain from cooperative communication and the relationship among influential factors. Simulation results demonstrate that the node density and traffic load greatly impact the effectiveness of cooperative communication.