Distributed Cooperative Precoding with Power Control for Cellular Systems with Correlated Antennas at the Receiver

Abstract

We consider the problem of cooperative precoding working alongside an antenna power allocation algorithm in the downlink of a correlated Multiple Input and Multiple Output (MIMO) interference channel. An analytical model for the multicell, multiuser system with receiver-side correlation is analyzed for a realistic system configuration having two antennas each at the basestation and user terminal. Based on the precoder choices of the different terminals and the per-antenna power levels requested, a criterion is proposed for maximizing the received SINR of a severely interference-limited cell-boundary user, while controlling the loss in performance of high-SINR in-cell users in the system. A distributed protocol for cooperation amongst the base stations is also proposed. System performance gains measured in terms of mean and cell-edge spectral efficiency values are provided using numerical simulations. An improvement of about 28% to the mean spectral efficiency and 115% to the cell-edge spectral efficiency is reported over single-cell beamforming. We also demonstrate that terminals with high receive-side correlation form a specific use case of this algorithm. With two antennas at the receiver and 0.9 correlation factor, an improvement of 37% in the mean spectral efficiency is reported. The proposed technique takes into account practical constraints such as limiting to a modest level the information exchanged from the user equipments to the serving base station and amongst the base stations.

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