Robust Design of Spatial Tomlinson-Harashima Precoding in the Presence of Errors in the CSI

Abstract

In this letter, we study spatial Tomlinson-Harashima precoding (STHP) from an information theoretic point of view encompassing both the single and the multiuser scenarios. Since the performance of any communications precoding scheme relies on the quality of the channel state information (CSI) that is made available at the transmitter side, in this work we focus our attention on the analysis of the robustness of STHP in terms of rate loss when the CSI is imperfect. Precisely, we present a robust design of the set of moduli used in STHP and, consequently, of the corresponding power allocation, that maximizes the achievable rates for the worst-case errors in the CSI in the small errors regime.

Analysis and Design of Tomlinson-Harashima Precoding for Multiuser MIMO Systems

“…Therefore, the robust transceiver design which takes into account the uncertainties of CSI at the transmitter (CSIT) is required. Several robust schemes have been proposed for THP in the multiuser MISO downlink, which can be classified into the worst-case approach (Payaro et al, 2007;Shenouda & Davidson, 2007) and the stochastic approach (Dietrich et al, 2007;Shenouda & Davidson, 2007). The worst-case approach optimizes the worst system performance for any channel error in a predefined uncertainty region.…”

“…The worst-case approach optimizes the worst system performance for any channel error in a predefined uncertainty region. In (Payaro et al, 2007) a robust power allocation scheme for THP was proposed, which maximizes the achievable rates for the worst-case errors in the CSI in the small errors regime. The authors of (Shenouda & Davidson, 2007) designed the THP transmitter to minimize the worst-case MSE over all admissible channel uncertainties subject to power constraints on each antenna, or a total power constraint.…”

Performance degradation of telecommunication transceivers due to parameter estimation errors

“…One way to proceed is to use the channel estimate as if it were the true channel; this is sometimes called the mismatched or naive approach. Another way is to exploit the statistical description of the channel uncertainties and develop robust designs; see, for example, [6], [23] and [25]. However, in all cases, the design of the MIMO-TH filters is based on inexact channel estimates and thus performance degradation is inevitable.…”