Spreading Strategies for MIMO-CDMA in Presence of Channel Estimation Errors and Spatial Correlation

Parity bit selected spreading and permutation spreading have been proposed as alternative techniques for assigning spreading codes to different users in a multiple input multiple output Direct-Sequence Code Division multiple Access (MIMO-CDMA). In frequency selective fading with perfect channel estimates and in the absence of spatial correlation, the two techniques have similar performance in terms of quality of service and capacity. In this paper, channel estimation errors and spatial correlation effects are considered to study the robustness of these two spreading strategies. Simulation results show that both spreading strategies outperform the conventional system. Moreover, permutation spreading system is much more robust when compared to parity bit selected spreading system in the presence of spatial correlation and channel estimation errors.