Separable MSE-based design of two-way multiple-relay cooperative MIMO networks

03/03/2020

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by   Donatella Darsena, et al.

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We consider the problem of jointly optimizing terminal precoder/decoders and relay forwarding matrices on the basis of the sum mean-square-error (MSE) criterion in multiple-input multiple-output two-way relay systems, where two multi-antenna nodes mutually exchange information via multi-antenna amplify-and-forward relays. This problem is non-convex and a local optimal solution is typically found by using iterative algorithms based on alternating optimization. We show how the constrained minimization of the sum-MSE can be relaxed to obtain two separated subproblems which, under mild conditions, admit a closed-form solution. Compared to iterative approaches, the proposed design is computationally more affordable and its performance exhibits a better scaling in the number of relays.