Research On Multi-cell NOMA MIMO Network Based On Topological Interference Management

As a promising wireless access technology for new-generation mobile communication system,non-orthogonal multiple access(NOMA)technology,especially combined with multiple-input multiple-output(MIMO),has attracted considerable attention of scholars.Consider the interference problem caused by the downlink power allocation principle in the multi-cell NOMA MIMO scenario,an efficient interference management scheme,Topological interference management(TIM),is introduced into the multi-cell NOMA MIMO to align the interference.This paper focus on studying the TIM problems in multicell downlink NOMA MIMO scenario,which can be divided into the following two specific problems through considering whether the inter-cell interference topology is alternating during communication.(1)A practical hybrid IA-TIM scheme is proposed without requiring the full channel state information at transmitters(CSIT)through considering the inter-cell interference connectivity is fixed during transmission.Actually,IA-TIM scheme aims to remove intercell interference,inter-cluster interference and intra-cluster interference in a general multi-cell downlink NOMA MIMO scenario,in order to guarantee Quality of Service(QoS)of users and improve system throughput.Compared with the existing NOMA MIMO algorithm with no global CSIT,IA-TIM scheme can serve the maximum number of users simultaneously while realizing the maximum single-cell system throughput without requiring the additional number of antennas and system overheads.(2)We focus on studying the achievable degrees of freedom(DoF)outer bound of the two-cell and three-cell downlink NOMA MIMO system under alternating connectivity states respectively,through considering the inter-cell interference connectivity is alternating during transmission.Furthermore,all possible connectivity states have been summarized and each state has a probability of occurrence,which provides the basis for deriving the theoretical DoF outer bound of the network via exploiting Fano's inequality.Additionally,the jointly coding over the states transmission is proposed to confirm the derived DoF result is achievable and tight.