Cluster-based control channel design using discrete OFDM for opportunistic spectrum access ad hoc networks

In this paper, we propose a novel spectrum-aware clustering scheme for distributed coordination in CSMA/CA-based cognitive radio networks (CRNs). The proposed scheme employs a CSMA/CA mechanism to asynchronously organize neighboring CR users with similar views to spectrum into virtual clusters, and coordinate their communications using locally available common control channels (CCCs). Our scheme differs from existing cluster-based schemes in that it exploits the Discrete Orthogonal Frequency Division Multiplexing (D-OFDM) technology to reduce neighbor-discovery time and facilitate inter-cluster communication and broadcasting. Our scheme enables efficient control channel migration, provides higher bandwidth to CR users and reduces the frequency of re-clustering. Two variants of our scheme are presented that provide different cluster size based on the considered neighborhood area. Simulation results show that the proposed scheme outperforms existing cluster-based coordination schemes without imposing synchronization.