Abstract :
In this paper we investigate the performance of downlink transmission in multiuser MIMO system with linear precoding. Specifically, we perform diversity analysis of MIMO systems that use block-diagonalization and Wiener precoding. It is known that MMSE equalizers and their counterpart Wiener precoding induce a complicated diversity-rate tradeoff that is function of the number of antennas and the operating spectral efficiency in the case of single user. In this paper we provide the diversity-rate tradeoff when Wiener precoding is used in downlink MIMO multiuser system. Block diagonalization, a common precoding technique that was proposed for downlink MIMO, is also analyzed under MMSE equalization and Wiener precoding. It is shown that block diagonalization does not improve the per-user diversity that is obtained in the case of Wiener precoding. The maximum per-user diversity achieved by Wiener precoding is (M-(N-Nk) Nk, where M is the number of transmit antennas, Nk is the number of receive antennas for user k, and N = ∑kNk.
