Information Exchange Limits in Cooperative MIMO Networks

TL;DR

This paper shows that limited finite-bit information exchange in cooperative MIMO networks suffices to achieve optimal capacity scaling, and this exchange level does not increase with the number of users, unlike previous strategies.

Contribution

It demonstrates that finite, bounded information exchange enables optimal capacity scaling in multi-cell multiuser networks, reducing the need for extensive inter-base-station communication.

Findings

Finite-bit feedback and cooperation achieve optimal capacity scaling.

Information exchange level is independent of user count.

Less exchange needed than existing infinite-bit strategies.

Abstract

Concurrent presence of inter-cell and intra-cell interferences constitutes a major impediment to reliable downlink transmission in multi-cell multiuser networks. Harnessing such interferences largely hinges on two levels of information exchange in the network: one from the users to the base-stations (feedback) and the other one among the base-stations (cooperation). We demonstrate that exchanging a finite number of bits across the network, in the form of feedback and cooperation, is adequate for achieving the optimal capacity scaling. We also show that the average level of information exchange is independent of the number of users in the network. This level of information exchange is considerably less than that required by the existing coordination strategies which necessitate exchanging infinite bits across the network for achieving the optimal sum-rate capacity scaling. The results provided rely on a constructive proof.