Analyzing the Channel Aging Effects on Massive MIMO Downlink by Ray-Tracing

The influence of channel aging effects on massive Multiple-Input Multiple-Output (MIMO) downlink performance for a single-cell urban scenario is investigated by ray-tracing simulations. The scenario comprises 256 base station antennas and 64 single antenna users, which are mobile and travel with a constant speed. Ray-tracing simulations are used to calculate the instantaneous channels in every 100 microseconds for a 10 milliseconds time span. The average downlink data rate in the network is calculated at each time instance. The deterioration of the performance is demonstrated when the channel state information (CSI) available at the base station gradually deviates from the actual channel. The procedure is repeated for different user speeds and different numbers of transmitter antennas. The results are compared to a statistical channel aging model where the aging effect is captured by introducing a correlation coefficient and a random error parameter to a previously known channel matrix.