Joint opportunistic spectrum access and scheduling for layered multicasting over cognitive radio networks

Cognitive radio (CR) represents an exciting new paradigm on spectrum utilization and potentially more bandwidth for exploding multimedia traffic. We focus on the layer encoded video multicast problem over CR and contribute 1) a quality based ranking in opportunistic spectrum access (OSA) for sub-channel selection, and 2) opportunistic layered multicasting (OLM) inspired scheduling designed particularly for CR networks. The 2-step ranking in OSA takes outcomes of periodic sensing and prediction to expand the system-wide throughput while keeping collision rates acceptable. By tracking group receiving rate across CR sub-channels and data expiration time, we are able to realize the OLM advantage under much more challenging CR environments. The overall joint opportunistic spectrum access and scheduling (OSAS) algorithm finds precise transmission parameters to heuristically reach maximum system utility. Favorable results comparing OSAS with not fully opportunistic methods demonstrate OSAS to be the best performing one.