Achievable Sum Rate Bounds of Zero-forcing based Linear
Multi-user MIMO Systems


C. B. Chae, and R. W. Heath Jr., and D. Mazzarese


Proc. of Allerton Conf. on Comm. Control and Comp., Sep. 27-29, 2006


In this paper, jointly optimized linear transmit beamforming and receive processing for the downlink of a multi-user multiple input multiple output (MIMO) system is investigated. In this system the base station, equipped with multiple antennas, transmits to several users, who are also equipped with multiple antennas. To solve the dimensionality constraint that conventional block diagonalization (BD) has, we use an iterative based coordinated beamforming (CBF) method and also consider block diagonalization with receive antenna selection (BDRAS) for performance comparison. We show the upper and lower bounds on ergodic sum rate of CBF and BDRAS. Analysis and simulation results show that the proposed beamforming always outperforms conventional BDRAS, and achieves a sum rate close to the MIMO broadcast channel (BC) sum capacity.

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