Semi-blind receivers for MIMO multi-relaying systems via rank-one tensor approximations

Abstract

This paper proposes two tensor-based receivers for multiple-input multiple-output (MIMO) multi-relaying systems capable of jointly estimating the channels and symbols in a semi-blind fashion. Assuming space-time coding at the source and relay stations, we propose an orthogonal design based on a parallel factor (PARAFAC) analysis of the coding structure. Exploiting the proposed tensor codes and the multi-linear structure of the resulting received signals, we show that the data model for every relay-assisted link after space-time combining/decoding has a Kronecker structure, which can be recast as a rank-one tensor corrupted by noise. The proposed receivers combine the tensor signals for the multiple cooperative links for joint channel and symbol estimation by coupling multiple rank-one tensor approximation problems. The first one is a coupled-SVD based receiver that estimates all the involved communication channels and transmitted symbols in closed form. The second one is an iterative solution based on alternating least squares. The performances of both receivers are evaluated by means of computer simulations in a variety of system configurations. Our results show the effectiveness of the proposed receivers and its good performance-complexity trade-off in comparison with competing receivers.