Interference Alignment based on Alamouti Code for M x 2 X Channels with Multiple Antennas

We consider M x 2 X channels with M +1 antennas at each node. The proposed scheme achieves both the optimal degrees of freedom (DoF) of 2M for the considered channel and the diversity order of 2 simultaneously. The key to achieving them is to design beamformers using interference alignment (IA) scheme with Alamouti codes. Furthermore, the proposed scheme requires 2 symbol extensions. We assume that each transmitter has local channel state information at transmitter (CSIT) and each receiver has full channel state information at receiver (CSIR).