Sum-rate maximization and robust beamforming design for MIMO two-way relay networks with reciprocal and imperfect CSI

Abstract

In this paper, we investigate the robust relay beamforming design for a multi-input multi-output (MIMO) two-way relay networks (TWRN) by considering imperfect and reciprocal channel state informations (CSIs). In order to maximize the sum-rate (SR) subject to the individual relay power constraint, we first equivalently convert the objective problem into a sum of the inverse of the signal-to-residual-interference-plus-noise ratio (SI-SRINR) problem. The SI-SRINR problem can be reformulated as a biconvex semi-definite programming (SDP) which employs bounded channel uncertainties as the worst-case model. Then, we convert residual-interference-plus-noise (RIN) and relay power constraints into linear matrix inequalities (LMIs). By this way, the objective problem can be tackled by the proposed efficient iterative algorithm. The analysis demonstrates the procedures of the proposed SI-SRINR robust design.

Decoupled beamforming techniques for distributed MIMO two-way multi-relay networks with imperfect CSI

“…In this section, we examine the performance of the proposed decoupled scheme in terms of the average weighted SR and the convergent performance compared with the case with perfect CSI, the maximal-ratio transmission (MRT) and the SI-SRINR scheme in [8]. In all simulations, spatially uncorrelated Rayleigh fading channels with unit variance are assumed.…”

“…This is reasonable, since considering the high transmit SNR, (31) is very close to the original one which has the the negligible performance lose. Figure 3 compares the convergence performance of the weighted SR for the proposed method with the SI-SRINR in [8], where we have fixed α 2 i = β 2 i = 0.01. Two cases are considered: (1) λ 1 = 6, λ 2 = 1 with SNR = 30 dB and (2) λ 1 = 3, λ 2 = 1 with SNR = 20 dB.…”

“…Cooperative two-way relay network (TWRN) technology has attracted significant interests due to the superior spectral efficiency. Several relaying schemes haven proposed, i.e., amplify-and-forward (AF) [5][6][7][8], decode-and-forward (DF) [9,10], and denoiseand-forward (DNF) [11,12]. Specifically, the cooperative relaying beamforming design has been studied in [13][14][15][16], where the authors showed the optimal solutions of the source and/or relay beamforming matrices.…”

“…Considering inaccurate channel estimation and feedback delay, the perfect channel state information (CSI), which is proposed in the above works [5][6][7][8][9][10][11][12][13][14][15][16][17][18], is usually hard to obtain in practice. By taking account into the channel uncertainties, the imperfect CSI scenario has been studied in [20][21][22][23][24][25].…”

Generalized Beamforming Design for Cooperative MIMO Multirelay Networks with Infinite Constraints and Imperfect CSI

“…Furthermore, in [21][22][23][24][25][26], the generalization of S-Lemma to complex-valued variables and multiple semi-infinite (SI) constraints are presented. They have investigated iterative algorithms based on alternating convex search (ACS) to devise practical algorithms for solving the semi-infinite problems.…”