In this paper, we consider a two-way multiple-input multiple-output (MIMO) relaying system employing simplified space-time (ST) coding at both sources. The signals received at each source form a third-order tensor, which satisfies a parallel tucker2 (PARATUCK2) model. Exploiting this structure, we present a novel semiblind united alternating least squares (Uni-ALS) receiver for jointly estimating the transmitted symbols and the individual channels. The identifiability and uniqueness conditions are analyzed. In contrast to training-based receivers, such as tensor-based channel estimation (TENCE), two-stage training (TST) and zero forcing (ZF) receiver, the proposed receiver improves the spectrum efficiency. Simulation results show that the proposed receiver yields superior performance in comparison with the two-stage training (TST) receiver.

在本文中，我们考虑在两个源处都采用简化的时空（ST）编码的双向多输入多输出（MIMO）中继系统。每个源处接收到的信号形成一个三阶张量，该张量满足并行tucker2（PARATUCK2）模型。利用这种结构，我们提出了一种新颖的半盲联合交替最小二乘（Uni-ALS）接收器，用于联合估计传输的符号和各个信道。分析了可识别性和唯一性条件。与基于训练的接收机（例如基于张量的信道估计（TENCE），两阶段训练（TST）和零强迫（ZF）接收机）相比，所提出的接收机提高了频谱效率。仿真结果表明，与两阶段训练（TST）接收机相比，该接收机具有更高的性能。