Interference Aware-Coordinated Beamforming System in a Two-Cell Environment


Chan-Byoung Chae, Insoo Hwang, Robert W. Heath, Jr. and Vahid Tarokh


IEEE Transactions on Wireless, vol. 11, no. 10, pp. 3692-3703, October 2012.


In this paper, we propose jointly optimized linear transceiver algorithms called interference aware-coordinated beamforming (IA-CBF) for a two-cell system where each base station is equipped with multiple transmit antennas. To generalize IA-CBF to more than two-cell scenarios, a new beam-switching mechanism combined with IA-CBF is proposed. For a two-cell system, we derive a minimum-mean-square-error-type IA-CBF algorithm based on a lower bound on the achievable sum rate. We propose optimal (under an assumption of zero other-cell interference) and suboptimal transmit/receive beamforming vectors through zero-forcing IA-CBF algorithms. We also investigate the optimality of the proposed IA-CBF algorithms with respect to the number of receive antennas. Numerical results conŮrm that the proposed system with two transmit/receive antennas achieves the full degrees of freedom (a.k.a. multiplexing gain) of the two-cell multiple-input multiple-output channel while showing a better sum rate performance than competitive solutions such as noncooperative eigen-beamforming and interference nulling. A three dimensional ray tracing tool is also used to evaluate the proposed multi-cell IA-CBF algorithm.