Opportunistic Spectrum Access in Cognitive Relay Networks based on White Space Modeling

In this paper we investigate opportunistic spectrum access in cognitive radio networks when a decode and forward relay is employed. To better exploit the white space in primary networks, we propose two cognitive spectrum access approaches based on white space modeling, referred to as successive sensing based spectrum access and simultaneous sensing based spectrum access. We further study the optimal time allocation for the two-hop relay to minimize the outage probability of the cognitive data transmission. Numerical results show that the optimal time allocation heavily depends on the primary user traffic rate.