Bounds on Capacity Over Gaussian MIMO Multiaccess Channels with Channel State Information Mismatch

In this paper, we deal with the capacity of Gaussian MEMO multi-access fading channels when the channel knowledge available at the receiver and the transmitter is erroneous. First, upper and lower bounds on the multiaccess capacity region are presented when the channel state information is estimated by means of a MMSE criterion, and consequently, there exist some uncertainty on the channel knowledge. Then, the difference between these bounds for the joint mutual information is analyzed. A final expression for the ergodic sum-capacity gap is obtained as a function of the number of users, the quality of the channel estimates and the number of receive and transmit antennas. Computer results show that adding more users or transmit antennas reduces this gap in equal factor at high SNR