Abstract
Cognitive radio networks have emerged as a new trend in wireless technology due to their perfect solution to the spectrum scarcity. The critical aspect of the spectrum allocation in distributed cognitive radio networks is how efficiently the spectrum is managed and how the secondary user's (SU) link is maintained once the primary user (PU) arrives or when the channel degrades due to interference. The MAC protocol should allow access to unused spectrum holes without affecting the incumbent privileges, so the incumbent detection is required before and after starting using the band to avoid collision. To address this problem, in this paper a distributed cognitive MAC protocol is proposed to achieve compensation to the suspended secondary link and avoid collision with the primary which obviously increases the network performance. The 802.11 based backup channel reservation protocol (BCRP) is proposed to reconstruct the second communication if forced termination occurred. The protocol operates over a separate common control channel and multiple data channels; thus reservation information easily exchanged through the control channel which effectively enhanced quicker and smoother channel switching to the free sensed or reserved channel. A higher number of sensed channels lead to better chances to implement reservation procedure. The protocol effectively improves the network throughput due to a higher successful transmission as demonstrated by analysis and simulation.