Research On Full-Duplex Radio Access Networks

The future mobile communication system will be a unified network platform integratingmulti-technology,multi-spectrum and multi-protocol.In the case of satisfying the constraints about system bandwidth,energy efficiency and cost,the future mobile communication network needs to provide diversified transmission services according to the requirements of different services and applications.In this dissertation,we widely study the combination of future cellular networks and full duplex technology.We provide some schemes and suggestions for the future full-duplex wireless networks in terms of spectral efficiency,quality of service?QoS?,energy efficiency and transmission security.The main contributions of this thesis are summarized as follows.1)A novel hybrid-duplex scheme based on received power is proposed for heterogeneous networks?HetNets?.In the proposed scheme,the duplex mode?half-or full-duplex?of each user is switchable according to the received power from its serving base station?BS?.The signal-to-interference-plus-noise-ratio?SINR?and spectral efficiency are analyzed for both downlink and uplink channels by using the tools of inhomogeneous Poisson point process?PPP?.Furthermore,determining power threshold for duplex mode switching is investigated and an efficient algorithm is proposed to solve this problem.Simulation results show that the proposed hybrid-duplex scheme outperforms the half-duplex or full-duplex HetNet schemes.We also analyze some basic problems in the full duplex HetNets:the self-interference,the inter-cell interference and the unbalanced data rate between uplink and downlink.2)We propose a novel physical layer security scheme for HetNets,which is based on coordinated jammer selection and users'full duplex capability.Using the tools of stochastic geometry,we derive the expressions of connection probability and secrecy probability.In particular,the locations of active jammers are modeled by a modified Poisson hole process?PHP?for deriving more accurate user performance distribution.Based on these results,we propose a joint nonlinear programming to maximize the user connection probability subject to the given constraints of secrecy probability and secrecy rate.An algorithm is proposed to efficiently solve this problem.Simulation results show that our proposed algorithm could balance the performance of user connection probability and secrecy probability and improve the system performance.3)We investigate the energy efficiency in full duplex cloud radio access networks?C-RANs?with QoS constraints.We jointly optimize the beamforming vectors,the users'transmit power,the fronthaul compression ratio and the set of transmitting remote radio heads?RRHs?to minimize the network power consumption?NPC?.First,a user selection algorithm is proposed to find the largest subset of feasible users.Then we propose an algorithm based on the re-weighted ₁l-norm minimization method,the block coordinate decent?BCD?method and the successive convex approximation.The algorithm transforms the original non-convex problems into a series of convex problems.Furthermore,we comprehensively compare the basic characteristics of full-duplex and half-duplex C-RANs.Our study shows that the duplex mode should be chosen according to the application scenarios.The half-duplex mode is more suitable for the scenarios with low data rate requirements?e.g.Internet of Things?.On the other hand,full-duplex mode is more suitable for the scenarios with high data rate requirements?e.g.HD live streaming?.