CH-CSMA-CA: a MAC protocol for asynchronous channel hopping rendezvous in 802.11 DCF-based cognitive radio networks

Blind rendezvous paradigm recently expedites the approach to the control channel establishment problem in cognitive radio networks. As a result, many novel asynchronous channel hopping (CH) rendezvous schemes are proposed for realizing blind rendezvous in these years. However, how to integrate these asynchronous CH rendezvous schemes with CSMA/CA MAC has not been researched so far. In this paper, we propose a CH rendezvous based CSMA/CA MAC (named CH-CSMA/CA) to work with existing asynchronous CH rendezvous schemes by tailoring mechanisms of 802.11 DCF to the slotted operation manner of these rendezvous schemes. Moreover, we identify that the channel busy-time inconsistency problem unique to CH-CSMA/CAMAC design is caused by virtual carrier sensing (VCS) mechanism of 802.11 DCF, and an enhanced virtual carrier sensing (EVCS) mechanism is proposed to alleviate its impact on networking performance (i.e., channel access delay and throughput). Extensive simulation results verify the effectiveness of our MAC design.