Two-Way MIMO Decode-and-Forward Relaying Systems with Tensor Space-Time Coding
Résumé
In this paper, we present a new closed-form semi-blind receiver for a two-way decode-and-forward (DF) relaying system. The proposed receiver jointly estimates the symbol and channel matrices involved in the two-way relaying system by exploiting tensor structures of the received signals at the relay and the destination, without using training sequences. The proposed receiver exploits a cross-coding approach using a third-order tensor space-time code (TSTC) at the relay, and it does not require a channel reciprocity between uplink and downlink phases, which can be of interest in frequency division duplex relaying systems. The advantages of this DF receiver compared with the amplify-and-forward (AF) receivers of [14] are three-fold: 1) use of the DF protocol which makes it possible to attenuate the propagation errors compared to the AF protocol, at the cost of an additional decoding at the relay, 2) a cross-coding approach which allows the suppression of interference between sources and therefore greatly simplifies the receivers, and 3) the closed-form aspect of the receivers based on a least squares (LSs) Kronecker product factorization algorithm. Parameter identifiability and computational complexity are analysed, and simulation results are provided to corroborate the effectiveness of the proposed semi-blind receiver and coding scheme when compared with the AF receivers of [11].