| Nowadays,following the evolution of mobile wireless communication technology,people's life has changed dramatically.With the rapid development of smart terminal devices and the rise of Internet of Things(IoTs),especially the rapid development of new services and application scenarios represented by intelligent and connected transportation system,Virtual Reality(VR),Augmented Reality(AR)and telemedicine,the data traffic has shown explosive growth.The contradiction between the urgent demand for high-speed data transmission and the scarcity of spectrum resources is becoming increasing prominent.In order to address these problems,Device-to-Device(D2D)communications technology,as one of the key technologies of the 5th Generation Mobile Communication Network(5G),has attracted much attention,can expand the network capacity,reduce the core network load,and further enhance the performance of the communication system in terms of resource utilization efficiency,coverage,data signal transmission quality and multimedia application.In order to improve the utilization efficiency of the spectrum resources in the communication system,D2 D communication technology in the cellular network realizes the direct exchange of user information data by reusing the resources in the cellular network,which can effectively reduce the power loss of the system,improve the utilization rate of resources,strengthen the data transmission rate and user experience.Since D2 D communication does not need to be transited through base stations(BS),it reduces the latency of end-to-end data transmission while reducing the load of BS.In addition,unlike traditional short-range wireless communication technologies such as Zigbee,Bluetooth and WiFi,the D2 D communication in cellular networks works in the authorized band,which can establish a more reliable data transmission link under controlled interference conditions.Therefore,the D2 D communication in the cellular network can not only improve the performance of the existing cellular network,but also serve the emerging fields such as intelligent and connected transportation system,large-scale machine communication,and has a very broad application prospect.However,D2 D communication can also bring serious co-channel interference and reduce the performance of the communication system while reusing the authorized spectrum resources of cellular system to utilization ofnetwork resources.How to design a reasonable and effective resource allocation method for interference coordination is the focus and realization foundation for the resource of D2 D communication.This paper focuses on the key technology of resource allocation for D2 D communication underlaying cellular networks,and makes the following contributions:(1)The resource allocation of D2 D communication underlaying cellular networks is studied,then a link sharing and power allocation algorithm based on Quality of Service(QoS)guarantee is proposed.The resource allocation problem is modeled as a Mixed Integer Nonlinear Programming(MINLP)problem.Under the condition of ensuring the QoS requirements of the cellular users in the communication system,the Channel State Information(CSI)in the system is used to generate the candidate set of communication link for D2 D users.It is proved that the problem of power allocation is a convex problem when the D2 D users reusing the communication links of the cellular users,and the optimal transmission power of D2 D users is obtained.The Maximum Weight Bipartite Matching(MWBM)problem is solved by the Kuhn-Munkres(KM)algorithm,and the optimal cellular user is selected for D2 D users to reuse the communication link.The effectiveness and superiority of the proposed algorithm are verified by the simulation experiments,and the impacts of different network parameters on the performance of the resource allocation algorithm are analyzed.Simulation results show that the network transmission rate of the proposed algorithm is improved by about 41%.(2)The communication scenario where a single cellular user can reuse the link resources with multiple D2 D users is studied,a link selection and power control algorithm for D2 D communication based on multi-reusing is proposed.A heuristic-based low-complexity link selection mechanism for D2 D communication is proposed to find the appropriate link reusing resources for D2 D users.The power control problem for D2 D users is transformed into a convex optimization problem,then a Lagrangian dual function is constructed and the optimal solution of this power control problem is given according to the conditions of Karush-Kuhn-Tucker(KKT).The proposed algorithm breaks the limitation that a single cellular user can only reuse the link resources with a single D2 D user in the communication system.It not only improves the overall data transmission rate of the network,but also greatly enhances the access rate of D2 D users.Simulation results show that the network transmissionrate of the proposed algorithm is about 44% higher than that of single-reusing D2 D resource allocation algorithm.(3)The problem of joint power control for cellular users and D2 D users in multi-reusing D2 D communication is studied,then a power control algorithm for multi-reusing D2 D communication based on hierarchical game theory is proposed.Considering the QoS and maximum transmission power of cellular users and D2 D users,the transmission power of cellular users and D2 D users is mathematically modeled by optimizing the data transmission rate of the network.On basis of this,the hierarchical Stackelberg game is used to solve the optimization problem,and the existence of the Stackelberg equilibrium solution is also proved by mathematical derivation.The correctness of the theoretical derivation is verified by the experimental results and the influence of network parameters on system performance is analyzed.Simulation results show that the proposed algorithm improves the network transmission rate by about 8.93% compared with the power optimization of D2 D users alone.(4)The resource allocation problem for relay-aided D2 D communication underlaying cellular network is investigated.In the process of large-scale access of mobile terminals,the D2 D link may not be established due to the poor channel environment,so it is necessary to study the D2 D communication assisted by relay nodes.However,the complex topology of relay-aided D2 D communication also brings severe challenges to resource allocation.In order to reduce the signaling overhead and improve the data transmission rate of the system,a D2 D resource allocation algorithm based on social awareness is proposed to solve the problems of optimal relay node selection,communication mode selection,reusing link selection and power control for relay-aided D2 D communication by considering the influence of social relationship among users on resource allocation algorithm,the regional delineation mechanism and the Dinkelbach method.Numerical simulations verify that the social relationship among users can improve the data transmission rate of the network.Simulation results show that the network transmission rate of the proposed algorithm is improved by about 8.34%.In this thesis,four kinds of resource allocation algorithm for D2 D communication are proposed,which improve the utilization efficiency of spectrum resources and the data transmission rate of the network,and has a great reference significance for realizing large-scale D2 D terminal devices fast and seamless access and stable and efficient data transmission. |
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