Achievable DoF Regions of MIMO Networks With Imperfect CSIT

Abstract

We focus on a two-receiver Multiple-Input-Multiple-Output (MIMO) Broadcast Channel (BC) and Interference Channel (IC) with an arbitrary number of antennas at each node. We assume an imperfect knowledge of local Channel State Information at the Transmitters, whose error decays with the Signal-to-Noise-Ratio. With such configuration, we characterize the achievable Degrees-of-Freedom (DoF) regions in both BC and IC, by proposing a Rate-Splitting (RS) approach, which divides each receiver's message into a common part and a private part. Compared to the RS scheme designed for the symmetric MIMO case, the novelties of the proposed block lie in 1) delivering additional non-ZF-precoded private symbols to the receiver with the greater number of antennas, and 2) a Space-Time implementation. These features provide more flexibilities in balancing the common-message-decodabilities at the two receivers, and fully exploit asymmetric antenna arrays. Besides, in IC, we modify the power allocation designed for the asymmetric BC based on the signal space where the two transmitted signals interfere with each other. We also derive an outer-bound for the DoF regions and show that the proposed achievable DoF regions are optimal under some antenna configurations and CSIT qualities.

Achievable Rates of Gaussian Interference Channel with Multi‐Layer Rate‐Splitting and Successive Simple Decoding

“…We assume equal-power RS throughout this paper, i.e., , = / = , unless otherwise stated, since equalpower allocation is usually applied as a baseline in analyzing the achievable capacities in different systems with RS [25,26]. Correspondingly, the transmission signal of Tx-can be represented as…”

Linearly Precoded Rate-Splitting Techniques with Block Diagonalization for Multiuser MIMO Systems

“…However, most of the works on RS consider only multiple-input single-output (MISO) scenarios and zero-forcing and minimum mean-squared error (MMSE) channel inversion-type precoders. MIMO scenarios have been studied in [16] from a DoF perspective. In [17] a MIMO RS architecture has been proposed for millimetre waves using a ZF precoding.…”

Degrees of Freedom Region of the (M, N1, N2) MIMO Broadcast Channel with Partial CSIT: An Application of Sum-set Inequalities

“…The particular setting of the MISO BC, where each user is equipped with only one antenna, i.e., N 1 = N 2 = 1, has recently seen much progress based on the AIS approach in [4,11,12], leading ultimately to its full GDoF characterization in [12] with arbitrary channel strengths and arbitrary channel uncertainty levels. For arbitrary antenna configurations and arbitrary levels of partial CSIT, an achievable DoF region is established by Hao, Rassouli and Clerckx in [6]. The optimality of this achievable region has been shown in [6] for certain parameter regimes (mainly N 1 ≤ N 2 , M ≤ N 2 ), based on existing bounds, as well as AIS arguments.…”