Date Added: Jun 2011
In this paper, the authors propose jointly-optimized beamforming algorithms for cognitive networks to maximize the achievable rates assuming single information stream in both primary and secondary links. The primary and cognitive users share the same spectrum and are equipped with multiple antennas. No coordination is required between the primary and cognitive users and the interference cancellation is done at the cognitive user. Specifically, the beamforming vectors of the cognitive link are designed to maximize the achievable rate under the condition that the interference both at the primary and cognitive receivers is completely nullified. The sum rate performance of the proposed algorithms is evaluated by Monte Carlo simulations.