On Linear Precoding of Non-Regenerative MIMO Relays for QAM Inputs
Recent works have established that MIMO systems optimized for Gaussian source signals may suffer unexpected performance loss when practical inputs are in fact discrete QAM sources. There is a practical need in the optimization of MIMO related systems of various networking scenarios to specifically target source signals of finite QAM alphabet. In this paper, the authors investigate the pre-coding optimization of wireless two-hop non-regenerative three-node MIMO relay networks driven by finite alphabet inputs. Exploiting a known optimal structure for the pre-coder at relay and a special convexity property, they propose an iterative two-step numerical optimization algorithm.