Robust THP Transceiver Designs for Multiuser MIMO Downlink

Abstract

Abstract-In this paper, we present two robust nonlinear transceiver designs for multiuser multi-input multi-output (MIMO) downlink in the presence of imperfections in the channel state information at the transmitter (CSIT). Both the base station (BS) as well as the users are equipped with multiple antennas. The BS employs Tomlinson-Harashima precoding (THP) for interuser interference pre-cancellation at the transmitter. First, we consider the case where the CSIT error is Gaussian-distributed. In this case, the robust transceiver design seeks to minimize a stochastic function of the sum mean square error (SMSE) under a constraint on the total BS transmit power. We propose an iterative algorithm to solve this problem. Each iteration involves the solution of a second order cone program (SOCP). Next, we consider the case where the CSIT error can be specified by an uncertainty set. In this case, we consider a minimax design for the robust transceiver, where the worst-case SMSE is minimized under a constraint on the total BS transmit power. We show that this design problem can be solved by an iterative algorithm, wherein each iteration involves a pair of semi-definite programs (SDP). Further, we consider an extension of the proposed algorithm to the case with per-antenna power constraints. We illustrate the robustness of the proposed algorithms to imperfections in CSIT through simulations.

Robust non-linear precoding for downlink multiuser multiple-input multiple-output orthogonal frequency-division multiplexing systems with limited feedback

“…The iterative procedure is summarised as follows. First, the power allocation filters { f k (i)} K k=1 are initialised as f k (i) = 0 and at each iteration they are updated according to Theorem 1 where the filters { f j (i)} j.k from the previous iteration are used in (13). The filters are updated iteratively until the power allocation policy {n i (k)} across users and subcarriers converges.…”

Non‐linear transceiver design for multiple‐input–multiple‐output interference channel with statistical channel state information error

“…In [10], it maximised the minimum signal‐to‐interference plus noise ratio of each user by using THP to eliminate partial interference in multi‐cell system, but it assumed perfect CSI. Ubaidulla and Chockalingam in [11] focused on the robust THP design by minimising sum MSE in single‐cell multi‐user system, yet the results cannot be extended directly to multi‐cell MIMO interference channel.…”

Robust beamforming designs for multiuser MISO downlink with per-antenna power constraints

“…Moore-Penrose zero forcing (ZF)-based beamforming design was derived to maximize the minimum user rate in [23]. Aiming to minimize the stochastic or worst-case sum-MSE, a nonlinear Tomlinson-Harashima precoding (THP) design was investigated in [24] under per-antenna power constraints. Based on block coordinate ascent and signomial programming methods, beamforming designs were put forth to maximize the WSR for a multiuser downlink with power constraints per antenna groups in [25].…”