Tomlinson-Harashima Precoding Based Transceiver Design for MIMO Relay Systems With Channel Covariance Information

In this paper, we investigate the performance of the Tomlinson-Harashima (TH) precoder based nonlinear transceiver design for a nonregenerative multiple-input multiple-output (MIMO) relay system assuming that the full channel state information (CSI) of the source-relay link is known, while only the channel covariance information (CCI) of the relay-destination link is available at the relay node. We first derive the structure of the optimal TH precoding matrix and the source precoding matrix that minimize the mean-squared error (MSE) of the signal waveform estimation at the destination. Then we develop an iterative algorithm to optimize the relay precoding matrix. To reduce the computational complexity of the iterative algorithm, we propose a simplified precoding matrices design scheme. Numerical results show that the proposed precoding matrices design schemes have a better bit-error-rate performance than existing algorithms

ZF DFE transceiver design for MIMO relay systems with direct source-destination link

In this paper we consider a non-linear transceiver design for non-regenerative multiple-input multiple-output (MIMO) relay networks where a direct link exists between the source and destination. Our system utilises linear processors at the source and relay as well as a zero-forcing (ZF) decision feedback equaliser (DFE) at the receiver. Under the assumption that full channel state information (CSI) is available the precoding and equaliser matrices are designed to minimise the arithmetic mean square error (MSE) whilst meeting transmit power constraints at the source and destination. The source, relay, and destination processors are provided in closed form solution. In the absence of the direct link our design particularises to a previous ZF DFE solution and as such can be viewed as a generalisation of an existing work. We demonstrate the effectiveness of the proposed solution through simulation and show that it outperforms existing techniques in terms of bit error ratio (BER)

Optimal Beamforming for Non-Regenerative MIMO Relays with Direct Link

Abstract—In this letter, we generalize the existing works on the design of the optimal relay amplifying matrix for nonregenerative multiple-input multiple-output (MIMO) relay communication systems by including the direct source-destination link. We show that for most commonly used objective functions, the optimal relay amplifying matrix has a general beamforming structure, that is, the relay first sets beams to the direction of the source-relay channel, then conducts a linear precoding, and finally beamforms towards the direction of the relay-destination channel. Index Terms—MIMO relay, linear non-regenerative relay, direct link. I

Optimal Joint Source and Relay Beamforming for MIMO Relays with Direct Link

In this letter, we investigate the optimal structure of the source precoding matrix and the relay amplifying matrix for non-regenerative multiple-input multiple-output (MIMO) relay communication systems with the direct source-destination link. We show that both the optimal source precoding matrix and the optimal relay amplifying matrix have a beamforming structure. Based on this structure, an iterative joint source and relay beamforming algorithm is developed to minimize the mean-squared error (MSE) of the signal waveform estimation. Numerical example demonstrates an improved performance of the proposed algorithm

Transceiver design for non-regenerative MIMO relay systems with decision feedback detection

In this paper we consider the design of zero forcing (ZF) and minimum mean square error (MMSE) transceivers for non-regenerative multiple input multiple output (MIMO) relay networks. Our designs utilise linear processors at each stage of the network along with a decision feedback detection device at the receiver. Under the assumption of full channel state information (CSI) across the entire link the processors are jointly optimised to minimise the system arithmetic mean square error (MSE) whilst meeting average power constraints at both the source and the relay terminals. We compare the presented methods to linear designs available in the literature and show the advantages of the proposed transceivers through simulation results

Transceiver optimization for interference MIMO relay systems using the structure of relay matrix

In this paper, we study the transceiver design problem for amplify-and-forward interference multiple-input multiple-output (MIMO) relay communication systems, where multiple transmitter-receiver pairs communicate simultaneously with the aid of a relay node. We aim at minimizing the mean-squared error (MSE) of the signal waveform estimation at the receivers subjecting to transmission power constraints at the transmitters and the relay node. Since the transceiver optimization problem is nonconvex with matrix variables, the globally optimal solution is intractable to obtain. To overcome the challenge, we propose an iterative transceiver design algorithm where the transmitter, relay, and receiver matrices are optimized iteratively by exploiting the optimal structure of the relay precoding matrix. Simulation results show that the proposed algorithm performs better than the existing technique in terms of both MSE and bit-error-rate

MMSE based transceiver design for MIMO relay systems with mean and covariance feedback

In this paper, the problem of transceiver design in a non-regenerative MIMO relay system is addressed, where linear signal processing is applied at the source, relay and destination to minimize the mean-squared error (MSE) of the signal waveform estimation at the destination. In the proposed design scheme, optimal structure of the source and relay precoding matrices are obtained with the assumption that the relay knows the mean and channel covariance information (CCI) of the relay-destination link and the full channel state information (CSI) of the source relay link. Based on this assumption, an iterative joint source and relay precoder design is proposed to achieve the minimum MSE of the signal estimation at the destination. In order to reduce computational complexity of the proposed iterative design, a suboptimal relay-only precoder design is proposed. A numerical example shows that the performance of the proposed iterative joint source and relay precoder design is very close to that of the algorithm using full CSI