Power allocation and user selection in multi-cell massive MIMO systems

This paper investigates user selection and power allocation algorithms in multi-cell massive Multiple-Input Multiple-Output (MIMO) systems. The focus is on designing an algorithm that maximizes a particular cell of interest's sum rate taking into consideration the interference from other cells. This research extends previous work and proposes suboptimal per cell resource allocation models that are feasible in practice. The proposed algorithm models the inter-cell interference in terms of the intra-cell interference by assuming that the statistical properties of the intra-cell interference in the cell of interest are the same as in the other interfering cells. The inter-cell interference is therefore expressed in terms of the intra-cell interference multiplied by a correction factor. The correction factor takes into consideration pilot sequences used in the interfering cells in relation to pilot sequences used in the cell of interest and large scale fading between the users in the interfering cells and the users in the cell of interest. A mathematical model is proposed for maximum user scheduling in the cell of interest. The scheduled users are then optimally allocated power using the multi-level water filling approach. Performance analysis and evaluation of the developed algorithms have been presented mainly through extensive simulations. The proposed algorithm has also been compared to existing solutions. In general the presented results demonstrate that the proposed algorithm performs better than the existing solutions.