Multi-hop cooperative spectrum sensing in cognitive radio network

Cognitive radio (CR) technology has been proposed to improve spectrum utilization by allowing CR users to opportunistically access under-utilized frequency band. One requirement to CR system is to reliably detect signals from licensed users to avoid harmful interference. Due to the effects of the channel fading and shadowing, individual CR user may not able to reliably detect the presence of a licensed user. In this paper, we propose a multi-hop cooperative spectrum sensing for a CR network for the purpose of improving its sensing performance. In the proposed scheme, a few CR users which can not communicate with the Fusion Center (FC) by one hop due to the limited communication range will report the sensing information to the FC using multi-hop. In this way, a few CR users that are nearer to FC will receive sensing information from others, update their sensing information and further report to the FC. Therefore, the proposed scheme can take advantage of the variability of the signal strength at various locations of CR users to improve both local and global sensing performance.