A Framework for Cooperative In-Band Sensing in Cognitive Radio Network

Many existing in-band sensing algorithms for CRNs adopted a periodic sensing/transmission architecture, where all the CR users do periodic sensing. Each periodic detection cycle is divided into two parts: sensing and transmission times. Sensing times are affected by many factors. In some worse scenarios (e.g., low SNRs), it may take more than half of the channel idle time for sensing. In this paper, we propose a new cooperative in-band sensing framework to increase sensing efficiency and robustness. In our framework, each CR operates in one of the two modes: Transmission and Sensing. The CRs that have data to send switch to Transmission Mode, provided that there is enough number of CR nodes in sensing mode. Therefore, CRs in transmission mode do not have to do any sensing during transmission, which imply that they can send for longer times. CRs in sensing mode send warning messages in case they detected the presence of PU. This cooperation (among CRs) is done on the same channel of transmission without the need for a CCC. Simulation and analytical results show that our sensing framework outperforms traditional sensing framework/approaches that require periodic sensing. At the end, we identify a set of important open problems to be addressed under this sensing framework.