CSI feedback allocation in multicell MIMO channels

In this work¹, we consider the joint precoding across K transmitters (TXs), sharing the knowledge of the user´s data symbols being transmitted to K single-antenna receivers (RXs). We consider a distributed channel state information (DCSI) configuration where each TX has its own local estimate of the overall multiuser MIMO channel. Our focus is on the optimization of the allocation of the CSI feedback subject to a constraint on the total amount of feedback. As a starting point, we consider the Wyner model where we derive a distance-based CSI allocation achieving close to the optimal performance using only a small percentage of the total feedback. The approach relies on the exploitation of the attenuation to restrict the cooperation at a local scale. Indeed, the CSI and the user´s data symbols are then shared to only a finite number of neighbors such that our approach appears as an improved alternative to clustering.