The DoF Region of Two-User MIMO Broadcast Channel with Delayed Imperfect-Quality CSIT

TL;DR

This paper characterizes the degrees-of-freedom (DoF) region for a two-user MIMO broadcast channel considering delayed and imperfect-quality CSIT, providing insights into the impact of feedback delay and distortion on system capacity.

Contribution

It introduces a novel transmission scheme for the DoF region with delayed imperfect CSIT, bridging the gap between no CSIT and perfect delayed CSIT scenarios.

Findings

DoF region with delayed imperfect CSIT is between no CSIT and delayed CSIT regions.

A new transmission scheme adapts to imperfect CSIT quality.

The converse proof uses enhancement of physically degraded channels.

Abstract

The channel state information at the transmitter (CSIT) play an important role in the performance of wireless networks. The CSIT model can be delayed and imperfect-quality, since the feedback link has a delay and the channel state information (CSI) feedback has distortion. In this paper, we thus characterize the degrees-of-freedom (DoF) region of the two-user multiple-input multiple-output (MIMO) broadcast channel with delayed imperfect-quality CSIT, where the antenna configurations can be arbitrary. The converse proof of DoF region is based on the enhancement of physically degraded channel. The achievability proof of DoF region is through a novel transmission scheme design, where the duration of each phase and the amount of transmitted symbols are configured based on the imperfect-quality of delayed CSIT. As a result, we show that the DoF region with delayed imperfect-quality CSIT is located between the DoF region with no CSIT and the DoF region with delayed CSIT.