Power Region for Fading Multiple-Access Channel with Multiple Antennas

This paper studies the fading multiple-access channel (MAC) with additive Gaussian noise and multiple transmit and receive antennas. It is assumed that the receiver has the perfect channel state information (CSI) while the mobile transmitters have no such knowledge. This paper presents a transmission scheme where the receiver jointly optimizes the signal covariance matrices for all transmitters, based on the channel distribution information (CDI) and the rate demand of each individual user, and then feeds them back to all transmitters. Under this scheme the achievable multi-user power region that is composed of all transmit power-tuples with which a given set of "ergodic" rates is achievable for all transmitters, is characterized by using convex optimization techniques. It is observed from simulation results that the transmit optimization based on the CDI can provide substantial power savings in the fading MAC