The DoF region of two‐user MIMO broadcast channel with delayed imperfect‐quality CSIT

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, the degrees‐of‐freedom (DoF) region of the two‐user multiple‐input multiple‐output (MIMO) broadcast channel are characterised 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, it is shown 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.

The DoF Region of Order-(K - 1) Messages for the K-user MIMO Broadcast Channel with Delayed CSIT

“…Proof: The converse proof of Theorem 2 is similar to that in proving Theorem 1 via leveraging the converse proof in [34]. For the achievability proof of Theorem 2, it can be seen that only one corner point is off-coordinate, given by,…”