Compressed Sensing for Feedback Reduction in MIMO Broadcast Channels

TL;DR

This paper introduces compressive sensing-based opportunistic feedback schemes for MIMO broadcast channels, significantly reducing feedback resources while maintaining throughput, and demonstrating advantages in noisy environments.

Contribution

It presents a novel generalized feedback model and compressive sensing schemes for feedback reduction in MIMO systems, applicable to both analog and digital feedback.

Findings

Achieves same sum-rate throughput as dedicated feedback with logarithmic feedback growth

Reduces feedback noise in analog feedback, improving throughput

Digital feedback scheme nearly matches noiseless scenario performance in noisy conditions

Abstract

We propose a generalized feedback model and compressive sensing based opportunistic feedback schemes for feedback resource reduction in MIMO Broadcast Channels under the assumption that both uplink and downlink channels undergo block Rayleigh fading. Feedback resources are shared and are opportunistically accessed by users who are strong, i.e. users whose channel quality information is above a certain fixed threshold. Strong users send the same feedback information on all shared channels. They are identified by the base station via compressive sensing. Both analog and digital feedbacks are considered. The proposed analog & digital opportunistic feedback schemes are shown to achieve the same sum-rate throughput as that achieved by dedicated feedback schemes, but with feedback channels growing only logarithmically with number of users. Moreover, there is also a reduction in the feedback load. In the analog feedback case, we show that the proposed scheme reduces the feedback noise which eventually results in better throughput, whereas in the digital feedback case the proposed scheme in a noisy scenario achieves almost the throughput obtained in a noiseless dedicated feedback scenario. We also show that for a given fixed budget of feedback bits, there exists a trade-off between the number of shared channels and thresholds accuracy of the fed back SNR.