A Unified View of Information-Theoretic Aspects of Cognitive Radio

Cognitive radio carries bright prospects for very efficient utilization of spectrum in future. Since cognitive radio is still in its early days, many of its theoretical limits are yet to be explored. In particular, determination of its maximum information rates for the most general case is still an open problem. Till today, many cognitive channel models have been presented. Either achievable or maximum bit rates have been evaluated for each of these. This paper attempts to summarize all the existing results, makes a comparison between different channel models and motivates for future research work.