Interference Alignment Algorithms For Full-duplex Base Station Cellular Networks

While interference alignment can overcome the shortcoming of traditional interference processing methods,it has been applied to varied interference channel(IC)models to suppress interference.In addition,the recent maturation of Self-Interference(SI)cancellation technology has made full-duplex(FD)wireless communication technology possible.In the most typical application,a FD BS can simultaneously receive and transmit data in the same frequency band,which can effectively improve the spectrum efficiency of the network.Therefore,in this thesis,we studied a time-slot IA algorithm that global channel state information(CSI)is not need,and the complexity is reduced.Besides,this paper studies the IC based on the IA technology,specifically the trade-off relationship between diversity gain and multiplexing main.The main contributions of this thesis are as follows:1.A FD BS cellular network system model which users own single antenna is established,and the upper bound of its theoretical degree of freedom is discussed.Aiming at the cochannel interference(CCI)between uplink and downlink users,the interference alignment algorithm for uplink user precoding is studied separately in the base station antenna symmetry system and asymmetry system respectively,and the performance of the IA algorithm is simulated.2.In the FD BS cellular network with angle antenna users,a time-slot interference alignment method is proposed.By designing a reasonable precoding matrix in the BS and interference cancellation matrix at the downlink users.The interference at downlink users form uplink uses can be eliminate by subtracting different sub-slot signals.The research results show that when the DL user is only one,the upper bound Do F of FD System can be achieved,and the global CSI is not needed anymore.When the DL has multiple users,the Interference be achieved within a limited time slot by losing 0.5 Do F,and the CSI is not required either.3.Based on the single-antenna user FD cellular system,the algorithm is extended to a model with asymmetry BS antenna numbers.The algorithm can flexibly configure the number of uplink and downlink users according to the number of base station antennas.The algorithm designed in this paper is compared with the existing method of processing CCI in FD cellular network.The results showed that this time-slot IA algorithm can obtain a closed expression, figure users number flexibly,and the uplink users still do not need to obtain the CSI.4.In order to further study the performance of IC,this paper studies the trade-off relationship between the diversity gain and multiplexing gain(DMT)of the interference channel based on IA algorithm.First,the formula for traversing mutual information of K-users MIMO system and the formula of outage probability are deduced.On this basis,the mathematical relations of diversity gain and multiplexing gain are established.And we combined with the concept of multi-objective optimization,the optimization relationship of DMT is analyzed.