Cognitive beamforming algorithm

In cognitive radio, the cognitive users should ensure the communication of the primary users and avoid or control their interference to the primary users. Therefore, we proposed cognitive beamforming algorithm. DOA estimation, adaptive beamforming and DOA tracking will be considered to accomplish the dynamic cognitive transmission. After the direction angle of each signal has been obtained by the DOA estimation algorithm, the LCMV algorithm can form main beams in the direction of primary users and create nulls toward the main users. In the following procedure, the DOA tracking algorithm will be run on a smller spatial range rather than the whole range, which reduces the required processing time. Simulation results show the validity of the method.