On frequency-spatial channel correlation maps for MIMO-OFDMA systems

Channel correlation is usually tracked for adaptive channel estimation, prediction and network optimization. Time correlation is determined by the relative movement of the transmitter and the receiver, while frequency and spatial correlation depend on the environment layout that can be collected and stored for future use. In this paper, we introduce the concept of channel correlation map stored at the base station (BS), which adds both frequency and space direction channel correlation parameters as overlay information to a geographic map. We propose a measurement method of channel correlation maps by processing uplink transmission data and show the influence of available bandwidth on the measurement accuracy. Two application cases with the correlation map are shown through numerical simulation. One is adaptive MIMO-OFDM channel estimation without online tracking correlation parameters, the other is channel prediction for transmit scheduling and beamforming design to reduce the performance degradation due to outdated channel state information (CSI) caused by the feedback delay.