Abstract:
In cooperative cognitive radio systems (CRSs), where battery-powered cognitive radio terminals (CTs) frequently sense and report primary user’s (PU’s) existence to exploit a spectrum hole, energy efficiency (EE) is a challenging design issue. To improve EE in CRSs, letting only some of the CTs be active in sensing and reporting [called a quality-based activation (QBA)] is proposed in this letter. With QBA, CTs that have good channel quality in a data channel (DCH) as well as a reporting channel (RCH) are allowed to sense and report. A possible drawback of such conditional activation is that it could limit the participation of CTs in a scheduling procedure, and hence, may result in losing certain system throughput. Throughput and EE of CRSs with the proposed QBA are investigated and it is shown, with numerical examples, that QBA does not decrease the throughput and provides significant improvement in EE.
