Achievable rates in cognitive radio networks

In this paper, communication through an overlay cognitive radio network, wherein the cognitive ability of a secondary source needs to be acquired, i.e. the primary message may only be obtained by the cognitive source in a causal manner, is considered. A new achievable rate region for the discrete memoryless version of this network is derived using block Markov superposition coding (SPC), conditional rate-splitting, conditional Gel´fand-Pinkser (GP) binning, and cooperative relaying. This rate region is evaluated for Gaussian channels, and numerical results are presented to demonstrate the contributions of the various coding strategies, used in the proposed coding scheme, towards enlarging the achievable rate region.