PARATUCK semi-blind receivers for relaying multi-hop MIMO systems

Abstract

In this paper, two receivers are proposed for a multiple-input multiple-output (MIMO) relaying multi-hop communication system using a Khatri-Rao space-time (KRST) coding at the source and amplify-and-forward (AF) relays. It is shown that the third-order tensor of signals received at the destination satisfies a PARATUCK-(K+1) tensor model, where K is the number of relays. After formulating the system model, the expressions of the Cramér-Rao bound (CRB) for the communication channels are derived for the particular case of a two-hop system, i.e., K=1. The presented tensorial modeling enables a joint semi-blind estimation of the transmitted symbols and the channels. The first proposed estimation algorithm is a non-iterative technique based on a rearrangement of the Kronecker product, while the second proposed receiver is based on the alternating least squares (ALS) algorithm. The uniqueness of the tensor decomposition and the identifiability conditions of the proposed algorithms are discussed. The performance of these receivers is evaluated by means of Monte Carlo simulations.