Cooperative control feedback: On backoff misbehavior of CSMA/CA MAC in channel-hopping cognitive radio networks

Due to dynamic channel availability in cognitive radio networks (CRNs), rendezvous problem is known as the most challenging issue in the design of media access control (MAC) protocol, which is a key step for secondary users (SUs) to start communication. With the concept of blind rendezvous, numerous channel-hopping sequence (CHS) based rendezvous schemes have been proposed to solve this problem in these years. Currently, little attention is paid to the design of a carrier sensing multiple access/collision avoidance (CSMA/CA) MAC based on these rendezvous schemes and also the rendezvous de-synchronization problem brought by multiple rendezvous networking paradigm into MAC design. To this end, we propose a cooperative channel-hopping based CSMA/CA MAC (named CoCH-CSMA/CA MAC) which works on the top of existing CHS based rendezvous schemes. Resulting from the rendezvous de-synchronization problem, a new type of collision, named false collision, is identified. As a SU cannot discern the false collision by itself, we design a cooperative control feedback scheme which employs correlation-based signal detection to reduce the coordination overhead of cooperation and helps SUs to avoid backoff misbehavior. Moreover, we analyze the behavior of our MAC protocol and its advantage. Extensive simulations prove that the cooperative control feedback scheme can effectively alleviate the impact of rendezvous de-synchronization problem on backoff misbehavior and improve network performance.