Exploiting MIMO Antennas in Cooperative Cognitive Radio Networks
Recently, a new paradigm for cognitive radio networks has been advocated, where Primary Users (PUs) recruit some Secondary Users (SUs) to cooperatively relay the primary traffic. However, all existing work on such Cooperative Cognitive Radio Networks (CCRNs) operate in the temporal domain. The PU needs to give out a dedicated portion of channel access time to the SUs for transmitting the secondary data in exchange for the SUs' cooperation, which limits the performance of both PUs and SUs. On the other hand, Multiple Input Multiple Output (MIMO) enables transmission of multiple independent data streams and suppression of interference via beam-forming in the spatial domain over MIMO antenna elements to provide significant performance gains.