Efficient Cognitive MAC Protocol under WLAN Coexistence

Efficient Cognitive MAC Protocol under WLAN Coexistence

In the past few decades, with the development of mobile communication services in Wireless Local Area Networks (WLANs), the demand for available wireless spectrum has rapidly increased. In recent research, the traditional fixed spectrum assignment policy cannot use spectrum effectively in WLANs. A cognitive radio network (CRN) allows providing unlicensed users, called Secondary User (SU), with opportunistic access to the licensed bands without interfering with the existing users. In this paper, we propose a CRN MAC to use the spectrum of WLANs much more efficiently by allowing SUs to coexist with WLAN users. The proposed MAC aims to not only allocate an unused channel with better transmission quality for SUs, but also to guarantee the performance declination of the WLAN users below a pre-defined threshold. The latter is validated by a mathematical analysis based on Markov chain models. Further, simulation results show that the proposed CRN MAC is superior to a recent work in avoiding interference to the WLAN users, improving the throughput of spectrum, and inducing less overhead.