Study Of Interferencealignment In Coordinated Multiple Points System

With the development of science and technology, the increasing requirement for higher data rate in wireless communication will be harder to meet due to the limited frequency spectrum resources. In this situation, one of the main goals in system optimizing is to raise the total throughput of system without wasting anymore precious spectrum resources. The multi-antenna technology will be widely used to obtain higher spectrum efficiency in the future wireless cellular system. With the introduction of these new technologies, the co-channel interference becomes a huge challenge in system design. As a realization of coordinated multi-point transmission, interference alignment combines the transmitter beamforming and receiver interference suppression to reduce interference in multi-antenna system and achieves the optimal multiplexing gain by exploiting knowledge of channel state information of the interference network.In this paper, we analyze the realization methods of interference alignment in single-input single-output system and multi-input multi-output system grounded on the theory introduced in the beginning. Then we investigate the closed form solution of interference alignment available in SISO system and 3-users MIMO system. After that we focus on two iterative algorithms used to realize interference alignment in MIMO system containing more than three transmitter and receiver pairs, one of which could achieve the minimum of the total weighted leakage interference of the system while the other could achieve the maximum of the ratio of signal to interference plus noise at every receiver. On the base of theoretical analysis and simulation results, we reach the following conclusion. In the SISO system the closed form solution of interference alignment cause different bit error rates for different receivers in the network. In MIMO system, the MaxSINR algorithm shows better performance than the other two, obtaining the lowest BER when the SNR of receiver reaches about 20dB. Besides, when the SNR of receiver exceeds a certain threshold, the performance of the system will deteriorate in which the MaxSINR algorithm is applied.