Distributed user-centric clustering and precoding design for CoMP joint transmission

This paper addresses distributed interference management in downlink of multi-cell multiple- input multiple-output (MIMO) time division duplex (TDD) networks. Each user is associated with a user-centric cluster of base stations (BSs), which cooperatively serve the user through CoMP joint transmission. Clusters of different users possibly share some BSs such that they may overlap, being coupled by interference and transmit power constraints at each BS. Our objective is the design of BSs clustering and precoding matrices per-user in order to maximize the weighted sum- rate of the system by controlling the interference and the power spent at BSs. In contrast to previous works where all channel matrices in the system are needed, we propose a distributed procedure whereby only channel matrices towards a limited number of candidate BSs per user are required while interference is still controlled by using the signal received from an uplink transmission. For an LTE-compliant dense deployment of 2x2 MIMO BSs/users, results show gains of 6-16% in terms of sum-rate and 49-84% in terms of 5%-tile per-user rate (depending on the maximum cluster size) as compared to distributed BS-disjoint clustering schemes.