Two Branch Beamforming for the Three User Constant MIMO Interference Channel
We consider the interference alignment (IA) in the three user constant multiple input multiple output (MIMO) interference channel. A two branch transmit and receive beam-forming scheme is proposed, where the IA scheme of Cadambe and Jafar is applied to the top branches while the bottom branches help additional stream transmission without causing interference to the other users. This scheme is applicable without any restriction on the numbers of transmit and receive antennas and affords additional degree of freedom gain compared to the Cadambe and Jafar scheme. With the proposed scheme, the known degree of freedom upper bound \(\frac{3(M+N)}{4}\) of the beam-forming based IA is achieved in more general condition than the previous result for the three user constant MIMO interference channel, where \(M\) is the number of antennas at the transmitter and \(N\) is the number of antennas at the receivers.
the three user constant mimo interference channel interference alignment two branch beam-forming