Research On Joint Interference Alignment And Power Allocation In Multi-user MIMO Interference Channel

With the rapid increasing of mobile multimedia services and the number of users, the radio resource, especially spectrum resource has become more and more rare. How to utilize the limited spectrum resource efficiently is a critical problem to be solved. The MIMO technology can largely improve the reliability and the efficiency of the wireless communication system, without additional costs of the system bandwidth and the transmit power. However, interference will become especially large when adopting the multi-user MIMO system. Interference alignment(IA), as a new interference management technology, can provide better performance than the previous interference management technology.The topic in this thesis comes from the National Natural Science Foundation undertaken by my tutor. The thesis mainly studies the IA technology in the multi-user MIMO system, including the implementation of the IA technology, the classical distributed IA algorithms, the joint IA and power allocation algorithm. The detail works are as follows.(1)This thesis studies the implementation of interference alignment in MIMO X channel, K-user MIMO-IC and SISO-IC. Especially, more attention is paid to the realization of interference alignment in signal vector space and signal scale in 3-user MIMO-IC. Then comparison is taken between the IA scheme based on space domain and conventional orthogonal method for 3-user MIMO-IC. The simulation results show that, compared with orthogonal method, the IA scheme can obtain higher sum rate.(2)This thesis introduces five classical distributed IA algorithms, including Weighted Leakage Interference Minimization(Min-WLI)algorithm, SINR Maximization(Max-SINR)algorithm, Mean Square Error Minimization(Min-MSE)algorithm, Alternative Minimization(Alt-Min)algorithm and Rank Constrained Rank Minimization(RCRM) algorithm. The simulation results show that, in terms of the sum rate performance, the RCRM algorithm has the best performance, next are Max-SINR algorithm and Min-MSE algorithm, the Min-WLI algorithm and Alt-Min algorithm have the worst performance.(3)Considering the tradeoff between system performance and complexity of the algorithm, this thesis combines the Min-WLI algorithm with the power allocation algorithm, which allocates power for each data streams of each user, and proposes a joint IA and power allocation algorithm. This algorithm is iterative. The simulation results show that, compared with the Min-WLI algorithm with equal power allocation, the proposed algorithm can effectively decrease the total interference power and improve the throughput of the system.