Utilizing multiuser diversity for multiple antenna systems

Previous research has shown that the capacity of a multiple antenna system grows linearly with increasing number of antennas for rich-scattering environments. However, this is not true for wireless channels with a small number of independent paths. To overcome this problem, this paper investigates the possibility of exploiting the multiuser dimension with and without channel side information at the transmitter. First, the single user capacity per antenna is shown to converge to zero with increasing number of antennas for channels with a finite number of independent paths. Then multiuser capacity per antenna at the limit is shown to be positive. Simulation results are presented for a single user system and a multiuser uplink system