A Multi-channel MAC for Opportunistic Spectrum Sharing in Cognitive Networks

The spectrum of deployed wireless cellular communication systems is found to be under-utilized, even though licensed spectrum is at a premium. To efficiently utilize the band-width left unused in a cellular system, which we denote as the primary system (PRI), we design a system with an ad hoc/mesh overlay network, which we denote as the secondary system (SEC). The basic design principle is that the SEC operates in a non-intrusive manner and does not interact with the PRI. We develop a multi-channel MAC protocol, to enable the interoperation of the PRI-SEC system. We address a number of technical challenges pertinent to this networking environment, and evaluate the performance of MAC. Our performance evaluation results show that, in a single-hop ASN, the AS-MAC transparently utilizes 75% of the bandwidth left unused by the PRI, while, in multi-hop ASNs, due to spatial reuse, the AS-MAC can utilize significantly higher number of the idle PRI resources