Channel aware scheduling for multiple antenna multiple access channels

In this paper, we study the optimum transmission strategy of the multiple access channel in a cellular system in which the base station has multiple antennas. Recently, scheduling algorithms incooperating both the physical and data link layer were proposed e.g. in [1], [2], [3] for the multiple antenna case. In this work, we study the scheduling in a SIMO MAC under arbitrary ergodic fading. We assume that the instantaneous channel vector realizations as well as the buffer sizes of all mobiles are known at the base station. The base station performs successive interference cancellation. We propose the optimal scheduling policy. In order to get rid of the time-sharing argument, we define a spatial capacity region in which all rate tupels are achieved by spatial multiplexing only without time-sharing. Finally, we connect the capacity region of the SIMO MAC on the physical layer with the stability region of the corresponding queueing system on the data link layer. It is shown that all bit arrival rate vector lying in the capacity region of the SIMO MAC are achievable, too. All theoretical results are illustrated.