Abstract: An interference cancellation method based on space-time code and codeword space alignment was proposed for MIMO Y interference channel, which consists of three users and a relay. An alamouti-based space-time coded is designed for each user. Codewords after space alignment pre-coding are sent to the relay in two steps during the multi access stage. The symbols estimated at the relay are encoded and are sent to three users in two steps during the broadcast stage. Both the multi access stage and the broadcast stage occupy four time slots, in which 24 independent modulated symbols are transmitted. Compared with the existing scheme for the same scene, the proposed scheme greatly reduces the amount of feedback, while keeping the same transmission rate. Simulation results demonstrate that the reliability of the proposed scheme is very close to that of the existing scheme for the same scene.

Key words: interference alignment, Y channel, feedback amount, pre-coding, space-time code