Design of Robust Transceiver for Precoded Uplink MU-MIMO Transmission in Limited Feedback System

Abstract

This paper proposes a robust transceiver design against the effect of channel state information (CSI) estimation error to optimize precoded uplink (UL) multi-user multipleinput multiple-output (MU-MIMO) transmission in limited feedback system under the consideration of the least-square technique on CSI estimation. To improve this limited feedback precoding, the constrained minimum variance (MV) approach with quadratic form to realize the computationally-efficient optimization problem, advantageously invoking the characteristics of the CSI estimation error, is proposed to suppress the effect of CSI estimation error, multiple user interference and noise. According to the Lagrange multiplier method on this MV approach, the deterministic function to resist uncertain CSI can be obtained to optimize design of the precoder and adaptive matrices jointly. With these optimum adaptive and precoder matrices, an optimum robust weighting matrix can be obtained to facilitate the user-wise detection in precoded UL MU-MIMO system. Performance analysis shows that the proposed robust weighting matrix is an unbiased design and it also can regularize the diagonal loading factor technique, and the detection performance of the proposed robust transceiver design can be predicted simplistically by applying our derived signal-to-interference-plusnoise ratio formulation. Computer simulations are conducted to confirm the efficacy of the proposed design in both perfect and imperfect CSI estimation.

Exploring the physical layer frontiers of cellular uplink

“…Yet, for ZF OFDM the throughput of the individual CQIs follows almost a step function; hence, rate adaptation can be based on the long-term average SNR without substantial performance degradation. 4 In case N R > L, we can easily estimate the achievable rate of SC-FDM transmission: The per-layer SNR with ZF receivers is governed by the harmonic mean of the channel responses on the individual subcarriers, similar to ( 12)…”

“…Current cellular wireless communications employs Universal Mobile Telecommunications System (UMTS) Long Term Evolution (LTE) as the high data rate standard [1]. The increasing demand of high data traffic in up-and downlink forces engineers to push the limits of LTE [2], e.g., through enhanced multi-user Multiple Input Multiple Output (MIMO) sup-port [3,4], Coordinated Multipoint (CoMP) transmission/reception [5,6] as well as improved Channel State Information (CSI) feedback algorithms [7]. The authors of [8] predict further evolution of existing LTE/ LTE-Advanced (LTE-A) systems in parallel to development of new radio-access technologies operating at millimetre wave frequencies until 2020 and beyond.…”