Precoding Method Interference Management for Quasi-EVD Channel

Abstract

The Cholesky decomposition-block diagonalization (CD-BD) interference alignment (IA) for a multiuser multiple input multiple output (MU-MIMO) relay system is proposed, which designs precoders for the multiple access channel (MAC) by employing the singular value decomposition (SVD) as well as the mean square error (MSE) detector for the broadcast Hermitian channel (BHC) taken advantage of in our design. Also, in our proposed CD-BD IA algorithm, the relaying function is made use to restructure the quasieigenvalue decomposition (quasi-EVD) equivalent channel. This approach used for the design of BD precoding matrix can significantly reduce the computational complexity and proposed algorithm can address several optimization criteria, which is achieved by designing the precoding matrices in two steps. In the first step, we use Cholesky decomposition to maximize the sum-of-rate (SR) with the minimum mean square error (MMSE) detection. In the next step, we optimize the system BER performance with the overlap of the row spaces spanned by the effective channel matrices of different users. By iterating the closed form of the solution, we are able not only to maximize the achievable sum-of-rate (ASR), but also to minimize the BER performance at a high signal-to-noise ratio (SNR) region.

Low-complexity QL-QR decomposition- based beamforming design for two-way MIMO relay networks

“…For the non-regenerative MIMO relay systems [29], the authors investigate a precoding design for a 3-node MIMO relay network. In [2], a relay-aided system based on a quasi-EVD channel is proposed. We compare the required number of FOLPs of our proposed method with conventional precoding algorithm, such as the conventional RBD, the non-regenerative MIMO relay system, and the CD-BD algorithm as shown in Tables I, II, III, For instance, the (2, 2, 2) × 6 case denotes a system with three users (K = 3), where each user is equipped with two antennas (N i = 2) and the total number of transmit antennas is six (N T = 2 × 3 = 6).…”

“…Recently, wireless relay networks have been the focus of a lot of research because the relaying transmission is a promising technique which can be applied to extend the coverage or increase the system capacity. There are various cooperative relaying schemes have been proposed, such as amplify-and-forward (AF) [1] and [2], decode-and-forward (DF) [3], denoise-and-forward (DNF) [4], and compress-andforward (CF) [5] cooperative relaying protocols. Among these approaches, AF is most widely used due to without detecting the transmitted signal.…”

“…Since singular value decomposition (SVD) and/or generalized SVD (GSVD) are widely used to find the orthogonal complement to solve an optimization problem [2], [9], [16], [29], but their computational complexities are extremely high. In order to reduce the complexity, the SVD can be replaced with a less complex QR decomposition [18] in this work.…”