COGNITIVE RADIO NETWORKS BASED ON OPPORTUNISTIC BEAMFORMING WITH QUANTIZED FEEDBACK

In this paper, we consider an opportunistic beamforming scheduling scheme of secondary users (SUs) which can share the spectrum with a primary user (PU) in an underlay cognitive radio network, In the scheduling process, the cognitive base station (CBS) having multi-antennas, generates orthogonal beams which insure the minimum interference to the PU. Then, each SU feeds hack its maximum signal to interference and noise ratio (SINR) and the corresponding beam index to the CBS. The CBS selects the users having the largest SINRs for transmission. The aim of our work is to study the effect of SINR feedback quantization on the throughput of the secondary system. To do this, we derive an accurate statistical characterization of ordered beams SINK and then we derive the closed-form expression of the system throughput with SINK feedback quantization based on Lloyd-Max algorithm.