Iterative Receiver for Multi-Input Multi-Output (MIMO) Two-Way Wireless Relay Systems

In this paper, we propose an iterative receiver for a multi-input multi-output (MIMO) two-way wireless relay system. The two-way relay system requires two time slots to accomplish one information exchange. Compared to the traditional one-way relay system, which demands four time slots to complete one information exchange, our system only uses half as many time slots. Our proposed iterative receiver consists of two loops. One is the minimum mean square error (MMSE)-based iterative soft interference cancelation (SIC) algorithm which is extended from the algorithm in [1] to cover correlated noise environment incurred from the nature of signalling. The other is the Expectation Conditional Maximization (ECM)-based estimation algorithm. The MMSE-SIC algorithm provides the soft information of the transmitted signals and this information is transferred to the ECM-based estimation algorithm to update the channel information. Simulation results show that the performance of the iterative receiver proposed here is close to that given by perfect channel information with small number of iterations.