Spatial Interference Cancellation in MIMO Systems Using Side Lobe Canceller Structure

In this paper, a new MIMO receiver structure is proposed in which interferences are suppressed using a canceller operating in the spatial domain. The method presented in this paper is based on the assumption that a MIMO system with a certain number of antennas at the transmitter and receiver side is available. Distance between the antenna elements is subject to various factors and is selected in such a way that fading between different antenna pairs is independent of each other. In the proposed structure, without imposing additional restriction on the size of the array on the receiver, some auxiliary antennas are placed between every two adjacent elements to create antenna sets. Adaptive nulling is performed in each set to place nulls in the direction of the interferences. Then, the MIMO receiver processing is done such as is required in the conventional MIMO receiver without auxiliary antennas. In other words, the proposed structure added some auxiliary antennas to the MIMO receiver to cancel interferences that are separable in the spatial domain. To evaluate performance of the proposed structure, bit error rate (BER) of the conventional MIMO receiver and the proposed structure are compared in the space-time block-coded (STBC) MIMO system. Simulation results show that, in comparison with the conventional STBC technique, the proposed method has a better performance in the presence of interference.