Research On Key Technologies And Performance Analysis Of Non-orthogonal Multiple Access In Broadband Wireless Networks

Wireless communication has fully penetrated into human society,and has become an im-portant power to promote social progress and national economic development.Mobile inter-net and internet-of-everything(IoE)pose a great challenge to the fifth-generation(5G)and future sixth-generation(6G)broadband wireless networks,which require 5/6G to provide su-perior network performance and transform from conventional human-oriented networks to the ternary networks of human,machine and things.Firstly,emerging broadband multimedia ser-vices with super high quality and huge throughput,like virtual reality(VR)/augmented reality(AR),360° videos,ultra-high definition(UHD)videos,hologram and full-sense digital reali-ty,require wireless networks to achieve 10 Gbps to multi-Tbps data transmission.Secondly,massive machine-type terminals need wireless networks to support massive connectivity and achieve massive access communications.Finally,the applications like industrial internet,vehi-cle to everything(V2X)/self-driving and tele-medicine,require ultra-reliable and low-latency communications.Power-domain non-orthogonal multiple access(NOMA)will be an important technique for 5/6G,because it can obtain more degree-of-freedoms(DoFs)and has the advan-tages of high spectral efficiency,low-latency and supporting massive connectivity,by exploiting the power domain as a new resource domain to achieve multi-user superposition transmission by superposition coding.This thesis focuses on 5G and future 6G,and carries out the research on NOMA technique in order to improve the efficiency of data transmission.The main re-search contents of this thesis include advanced NOMA transmission and performance analysis with imperfect channel conditions and successive interference cancellation(SIC),downlink device-to-device(D2D)communications-based full-duplex user cooperative NOMA systems and performance analysis,full-duplex bidirectional NOMA relaying and performance anal-ysis,modeling and performance analysis of NOMA-based large-scale heterogeneous multi-cast/broadcast single frequency networks(MBSFN)and large-scale millimeter-wave NOMA multi-rate multicast/broadcast networks.To begin with,from the perspective of unordered users,the downlink NOMA systems with imperfect channel estimation and SIC are studied,the closed-form expressions for ergodic capacity and outage probability are derived,and the impacts of channel estimation error and SIC error on NOMA performance are revealed.Considering downlink NOMA systems with statistic CSI,a probabilistic NOMA transmission scheme is studied to improve the performance of NOMA user with weak statistic CSI,and the closed-form expressions for ergodic capacity and outage probability are derived.Rethinking NOMA transmission from the perspective of user collaboration,a revenue sharing-based downlink NOMA systems with imperfect channel estimation and SIC is studied,and the results demonstrate that NOMA users can share the gain of NOMA transmission according to the negotiated sharing proportion.Then,considering the problem that in downlink NOMA systems users with weak chan-nel conditions suffer from weak performance,we exploit the feature of NOMA that NOMA strong user with better channel condition can obtain the messages of other users through SIC decoding,study D2D communications-based downlink full-duplex user cooperative NOMA scheme by introducing full-duplex communications and D2D communications into downlink NOMA systems,and derive the analytical expression for outage probability of NOMA weak user.In this scheme,NOMA strong user working in full-duplex mode plays as user relay to cooperate the downlink data transmission for NOMA weak user through D2D communication-s.Furthermore,considering the performance tradeoff of full-duplex communications having residual self-interference,a downlink adaptive multiple access scheme is studied to achieve the dynamic switch among full-duplex user cooperative NOMA,NOMA and OMA,and the ana-lytical expression for outage probability of NOMA weak user is also derived.The results show that full-duplex user cooperative NOMA can improve the outage performance of NOMA weak user,while adaptive multiple access can further improve the outage performance of NOMA weak user.Next,for full-duplex NOMA relaying,we study three-node full-duplex bidirectional NO-MA relaying,which consists of two nodes and a relay working in full-duplex mode and has full DoF.The approximated closed-form expressions for average rates and outage probabilities of full-duplex bidirectional NOMA relaying with amplify-and-forward(AF)and decode-and-forward(DF)protocols based on physical-layer network coding(PNC)and analog network coding(ANC).The results show that full-duplex bidirectional NOMA relaying can achieve better average rate and outage probability than full-duplex OMA relaying,when residual self-interference is less than a certain threshold.Furthermore,considering NOMA for improving the performance of MBSFN,for hy-brid multi-multimedia broadcast/multicast service(MBMS)scenario,we exploit the chan-nel difference among MBMS user groups and study a NOMA-based multi-service multicas-ting/broadcasting scheme.We use stochastic geometry to model and analyze the performance of NOMA-based large-scale heterogeneous multi-service MBSFN with single cell and multi-cell transmission modes,and obtain the analytical expressions for coverage probability and multicasting/broadcasting throughput.Considering scalable MBMSs,a NOMA-based multi-rate multicasting/broadcasting scheme is studied,by utilizing the channel difference among users within MBMS user group.Using stochastic geometry,modeling and performance anal-ysis of NOMA-based large-scale heterogeneous multi-rate MBSFN with single cell and multi-cell transmission modes are studied,and the analytical expressions for coverage probability and multicasting/broadcasting throughput are also derived.The results demonstrate that both NOMA-based multi-service multicasting/broadcasting and NOMA-based multi-rate multicast-ing/broadcasting schemes can achieve superior performance to the OMA one.Finally,considering NOMA for enhancing the transmission performance of scalable MBM-S with super high quality and large throughput,we study a millimeter-wave NOMA multi-rate multicasting/broadcasting scheme.We use stochastic geometry to model and analyze the per-formance of large-scale millimeter-wave NOMA multi-rate multicasting/broadcasting network-s,and obtain the analytical expressions for coverage probability and multicasting/broadcasting throughput.Furthermore,considering the deployment of large-scale heterogeneous millimeter-wave networks,we exploit macro base stations(MSBs)to cooperate millimeter-wave small cells to transmit basic data layer of scalable MBMS,and study a millimeter-wave coopera-tive NOMA multi-rate multicasting/broadcasting scheme.Modeling and performance analysis of large-scale millimeter-wave cooperative NOMA multi-rate multicasting/broadcasting het-erogeneous networks are studied by using stochastic geometry,and the analytical expressions for coverage probability and multicasting/broadcasting throughput are also derived.The re-sults demonstrate that both millimeter-wave NOMA multi-rate multicasting/broadcasting and millimeter-wave cooperative NOMA multi-rate multicasting/broadcasting schemes can achieve higher throughput than the millimeter-wave OMA one,while millimeter-wave cooperative NO-MA multi-rate multicasting/broadcasting scheme can further improve the success probability that decoding the basic of scalable MBMSs and achieve superior coverage probability and throughput to the millimeter-wave NOMA one.