Distributed Cooperative Precoding with SINR-Based Co-Channel User Grouping for Enhanced Cell Edge Performance

We consider the problem of cooperative precoding for controlling interference in the downlink of a multiple-input and multiple-output (MIMO) interference channel. A model for the multicell, multiuser, MIMO system is analyzed, and a criterion to simultaneously maximize the SINRs of users sharing a common spectral resource is provided. An asymptotically optimal solution is then proposed as the number of users per sector (U) and the number of resources (B) in the system become large, within a specific framework for scheduling co-channel users in interfering cells. Based on this, a heuristic algorithm for distributed cooperative precoder selection (CPS) is proposed for application in practical systems with finite B and U values. System performance gains measured in terms of mean cell throughput and cell-edge spectral efficiency values are estimated using numerical simulations. The proposed technique takes into account practical constraints such as limiting the information exchanged from the user equipments to the serving base stations, and amongst the cooperating base stations, to a modest level.