Improved adaptive MMSE detector for downlink multi-cell MIMO signals

MIMO communication in the multi-cell has some differences to the MIMO based on point to point. In the multi-cell MIMO downlink environment, if all cells share the same frequency band, the mobile station (MS) that is near the boundary between cells will receive the adjacent cells´ interference. If the interference is disposed as Gaussian white noise by the detector and the received signal is detected by the linear MMSE algorithm, it must result in performance impairment. So the design of the detector must consider the interference of the adjacent cells besides the interference with multi-antennas of the intra-cell. But generally the mobile station cannot get the MIMO channel state information (CSI) in the adjacent cells. In this paper, we propose a partial zero-forcing (ZF) adaptive minimum mean square error (MMSE) detector with training data. This detector first removes the interference between multi-antennas within the local cell by using the ZF linear filter; the residual inter-cell interference can be greatly reduced by the adaptive MMSE filter vector. Compared with the conventional adaptive MMSE detector and linear MMSE detector, this proposed detector can speed up the convergence of adaptive filter weights and gain improved performance.