Time-slot Interference Alignment Algorithms For Full-duplex Base Station Cellular Networks

With the development of full-duplex(FD)technology,the self-interference(SI)caused by the base station(BS)has been well eliminated.The factor that make FD BS hard to use is the interference in the downlink users that uplink users caused.As an effective interference management method,interference alignment(IA)can be used in FD BS cellular networks,however,in practice,IA need the transmitter and receiver know the global channel state information(SCI),the method that the transmitters obtain the CSI is usually through the receiver's feedback,because of the feedback delay,quantization error,etc,the CSI is not always accurate,which make the IA not that good,meanwhile,the CSI's obtaining will bring a lot of burden to the system.Therefore,in this thesis,we studied a time-slot IA algorithm that uplink users do not need to obtain the CSI in full-duplex BS cellular netwok,and analyzed this IA algorithm's performance and complexity.The main contributions of this thesis are as following:Firstly,the system models of full-duplex BS have been setted up,and the upper bound of the theoretical degree of freedom(Do F)is discussed.In the single-antenna system and multi-antenna user system,as the FD BS will bring interferences between uplink and downlink users,consider to use the algorithms that the IA precoding is in uplink users respectively,and simulate the performance of the IA algorithms.Secondly,in the FD BS cellular networks with single-antenna users,the main problem is that the uplink users need to obatin the CSI,to solve this problem,we proposed a time-slot IA algorithms.This algorithm need the BS to amplify forward uplink users' datas to the downlink users.By designing a reasonable precoding matrix in the BS,the downlink users can align the interferences from the uplink users and the interferences from the BS's forwarding.Through theoretical analysis and simulation,it is shown that for this algorithms,the uplink users do not need to obtain CSI,and this IA can be achieved in two time slot,besides,this algorithms can achieve the upper bound of Do F in some specific user configuration.Thirdly,promote this algorithms to the multi-atenna system.,and propose an universal time-slot IA algorithms.This algorithm need the BS to design reasonable precoding matrix at BS and the interference cancellation matrix at downlink users,which make that in downlink users,they can combine different time-slots signals and eliminate uplink users' interferences.The results shows that this algorithm's system parameters are configurable,including the atenna numbers and the user numbers.The precoding of this algorithms is also in BS,and the uplink user still do not need to obtain the CSI.Fourthly,we anylized the feasibility and the Do F of the time-slot IA algorithm,and compared with the IA algorithms that precoding is in transmitter.The results shows that,the Do F gain of this time-slot IA algorithm is 1.5,the uplink users do not need to obtain the CSI,this algorithm can achieve the upper bound of Do F in some specific system configurations,besides,when the user is single-antenna,this IA algorithm can greatly reduce the time slots.