Hybrid Spectrum Access Strategy for Throughput Enhancement of Cognitive Radio Network

Recently, cognitive radio technology has gained worldwide attention due to its potential to overcome spectrum scarcity. The technology allows unlicensed users to use licensed spectrum in a manner such that minimum or no interference may be experienced by licensed users. To do so, the conventional scheme divides the time frame into two slots i.e. sensing slot and data transmission slot. In this scenario, the achievable throughput of unlicensed user fundamentally depends on the accuracy of sensing results since the sensing error in terms of miss detection and false alarm results into collision and spectrum underutilization, respectively. To overcome this bottleneck, an improved frame structure is proposed in this paper with two sensing slots and one data transmission slot. Based on the sensing results of the current and previous frame, the proposed scheme allows unlicensed users to switch between underlay and interweave mode of communication to enhance secondary user’s throughput. It is shown that proposed scheme has a potential to achieve 50% more throughput as compare to the conventional schemes, when channel is occupied by primary user. The simulation results are presented to illustrate the effectiveness of the proposed scheme. Moreover, the performance of proposed scheme is also compared with the conventional schemes to validate the results.