We propose a new vector precoding for the down-link of multiuser multiple-input multiple-output (MIMO) systems. The proposed scheme can be thought as the minimum mean square error (MMSE) version of the vector perturbation technique. We generalize the vector perturbation by allowing the data vector to be perturbed by an arbitrary vector. After the modulo operation at receivers, the remaining part of the perturbation is dealt with as the co-channel interference. We derive the total mean square error (MSE) of the received signal, and find the optimum perturbation vector that minimizes the total MSE. Simulation results show that our scheme outperforms the other compared schemes at all signal-to-noise ratios (SNRs), while the computational complexity is not increased.
"The VP of  was based on the ZF criterion, whereas the more powerful MMSE-VP solution was derived later in . The authors of  proposed a VP precoder design, where the data vector to be transmitted is perturbed by an arbitrary vector to minimize the total MSE, whereas the VP technique of  determines a continuous-valued perturbation vector that minimizes the MSE of the received signal. Although numerous different MMSE-VP techniques have been proposed –, the solution advocated in  was deemed to be the predominant MMSE- VP scheme –. "
[Show abstract][Hide abstract] ABSTRACT: We propose a generalized vector precoding (VP) design based on the minimum bit error rate (MBER) criterion for multiuser transmission in the downlink of a multiuser system, where the base station (BS) equipped with multiple transmitting antennas communicates with single-receiving-antenna mobile station (MS) receivers each having a modulo device. Given the knowledge of the channel state information and the current information symbol vector to be transmitted, our scheme directly generates the effective symbol vector based on the MBER criterion using the particle swarm optimization (PSO) algorithm. The proposed PSO-aided generalized MBER VP scheme is shown to outperform the powerful minimum mean-square-error (MMSE) VP and improved MMSE-VP benchmarks, particularly for rank-deficient systems, where the number of BS transmitting antennas is lower than the number of MSs supported.
"This work was supported in part by startup funds from the University of Victoria and in part by a Discovery Grant from NSERC. the transmit power. In –, joint optimal perturbation vector and precoding matrix under MMSE criterion are given. "
[Show abstract][Hide abstract] ABSTRACT: In multiple-input multiple-output (MIMO) broadcast channels, the base station transmits information to multiple noncooperative users simultaneously. With perfect channel state information (CSI) at the base station, vector perturbation (VP) precoding technique achieves full diversity order. In this paper, we study the symbol error rate (SER) performance of such systems with quantized channel feedback. The channel quantization is modeled by following the rate-distortion theory. Based on minimum mean square error (MMSE) criterion, we study the optimal design of precoding matrix and perturbation vector. Equivalent relations in terms of both MMSE and SER between quantized and perfect channel feedback cases are established, based on which we investigate the relation between feedback load and SER performance.
Global Telecommunications Conference, 2009. GLOBECOM 2009. IEEE; 01/2010
"Hence, in  the authors derived the MMSE vector precoding solution for transmission in frequency-flat fading multiuser scenarios with the aid of a multi-antenna transmitter. The authors of  proposed a vector precoder design where the data vector was perturbed by an arbitrary vector in order to minimize the total MSE. By contrast, in  a vector precoding technique was proposed, where a continuous-valued perturbation vector was found in order to minimize the MSE of the received signal. "
[Show abstract][Hide abstract] ABSTRACT: A novel vector precoding scheme is proposed for the downlink of a multiuser system equipped with multiple antennas transmitting to single-antenna aided mobile receivers. Our transmit preprocessing scheme first invokes a regularized channel inversion and then superimposes a perturbation vector to directly minimize the bit error ratio (BER) of the system as an improvement to the well-known minimum mean-square-error (MMSE) vector precoding scheme. Our simulation results demonstrate that the proposed vector precoding scheme achieves the same BER performance as the MMSE vector precoding at the same complexity, when only discrete vector perturbations are allowed. However, the performance of the proposed vector precoding scheme can be further improved based on the MBER criterion, when continuous-valued vector perturbations are carried out.
Vehicular Technology Conference, 2009. VTC Spring 2009. IEEE 69th; 05/2009
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