Diversity, interference cancellation and spatial multiplexing in MIMO mobile WiMAX systems

Multiple input multiple output (MIMO) techniques are an essential part of the IEEE 802.16e-2005 specifications, which form the basis of mobile WiMAX systems. In this paper, we first discuss the tradeoffs between diversity, interference cancellation and spatial multiplexing in MIMO systems, and we compare optimum combining (OC), maximum-ratio combining (MRC) and interference cancellation for different numbers of receive antennas. Then, we focus on the two mandatory MIMO profiles in the IEEE specifications (Alamouti's STC and the 2x2 spatial multiplexing scheme) and compare them when the first is combined with MRC at the receiver. The analysis obtained using the ITU pedestrian B channel in ideal conditions indicates that the two schemes lead to similar performance when they are operated at the same spectral efficiency