Achieving the Proportional Fairness in MU-MIMO Uplink Cellular Networks

In this paper, the optimal scheduling problem is studied to maximize network utility according to proportional fairness policy in multi-user multiple-input and multiple-output (MU-MIMO) uplink cellular networks. An optimization framework is developed to maximize the aggregate utility and to compute the optimal scheduling parameters in a single cell cellular network. The optimization problem is a very complex non linear program (NLP). The problem is solved numerically for several medium size network scenarios using an optimization tool. The numerical results show that MU-MIMO technique provides a significant utility gain over single user MIMO (SU-MIMO) technique. Further, the optimal scheduling parameters are determined analytically for the both SU-MIMO and MU-MIMO schemes. Interestingly, the optimal scheduling is found to be the same as the round-robin scheduling for the both MIMO schemes which is also validated by numerical computation. In this work, it is demonstrated that the simple round robin scheduling can achieve the proportional fairness in a SU-MIMO as well as a MU-MIMO uplink cellular network.