Interference cancellation method based on space-time code for MIMO interference channel

We investigate how to cancel interference by using space time code and codeword space alignment for multiple-input multiple-output (MIMO) Y channel consisting of three users and a relay. All the nodes adopt Alamouti code. During the multiple access (MA) stage, two codewords within each reciprocal codeword pair are aligned through pre-coding. The relay decodes the elements of each codeword pair using the orthogonal property of effective channel matrix of Alamouti codeword. During the broadcast (BC) stage, the interference between codeword pairs at each user is eliminated by the orthogonal property of effective channel matrix of Alamouti codeword, instead of the interference alignment (IA) pre-coding. Thus, channel state information (CSI) is not required during the BC stage, which greatly reduce the amount of feedback.