Energy-efficient framework for throughput enhancement of cognitive radio network

Recently, cognitive radio (CR) has evolved as a next-generation communication technology that has the potential to use the radio frequency (RF) spectrum in most efficient manner as compared to the other existing cellular communication technologies. The performance of CR system largely depends upon the accuracy of the sensing results. However, the sensing ambiguities such as false alarm and miss detection cause spectrum underutilization and severe interference to the primary user (PU), respectively. In this paper, both issues are addressed by modifying the conventional frame structure by introducing two sensing slots along with a transmission slot to overcome sensing ambiguities. For the targeted probability of detection, the first sensing slot is kept small and fixed, and sensing results are stored in a flag bit up to that duration. The second sensing slot (optional) is used whenever the flag bit status varies in the current frame from the previous frame. Considering sensing throughput trade-off issue of CR, the second sensing slot is optimized to enhance the effective throughput and energy efficiency of the secondary communication system. The simulation results are presented to validate the effectiveness of the proposed scheme with a modified frame structure, which is capable to achieve 65% higher energy efficiency than the conventional scheme when PU is present in a channel, that is, P(H-1) = 1.