Interpolation Techniques for MIMO OFDM with Interference Cancellation

A MIMO OFDM receiver with interference cancellation requires a channel estimation and matrix inversion on a sub-carrier basis. This is computationally intensive and can prevent a practical implementation. In this paper, we propose new interpolation algorithms for this type of receiver. To eliminate the need for a matrix inversion for each OFDM sub-carrier, the weight matrix is interpolated. Algorithms to determine the interference cancellation detection order are also introduced. The computation requirement of this receiver is greatly reduced while the performance degradation is acceptable. For example, for a normalized product of the rms delay spread by the interpolation factor below 6.25%, the degradation compared to the optimal solution is 2dB. The results also demonstrate that the impact of the sub-optimal interference cancellation detection order is non-significant compared to the coefficient matrix interpolation error and that using interference cancellation in a MIMO OFDM system with interpolation significantly improves the performance.