Research On Resource Allocation Algorithm For D2D Communications Underlaying Cellular Networks

With the explosive growth of communication data traffic,massive equipment terminal connections and new emerging communications services,critical demands comes up for the next-generation mobile network architecture and key technologies in the past few years.In order to meet the needs of users' diversified service and reduce the operating cost of operators,Device-to-Device(D2D)communication technology is introduced into cellular networks,which has aroused widespread academic research.D2D communication technology allows users in proximity communicate directly with each other without relaying via a base station(BS).This feature has many advantages such as reduce the load of BS,improve spectrum utilization,reduce terminal equipment energy consumption and offer diversified nearfield communication services to users.Currently,research on D2 D communication is mostly based on 5G and the Internet of Things.However,neither of them has a mature architecture,and the introduction of D2 D communication would also bring complicated and varied interference to the existing cellular network,which should be coordinated in reasonable and effective way to give full play to the advantages of D2 D communication.Therefore,it is very important to design a reasonable D2 D communication network architecture and wireless resource allocation algorithm.Considering the development trend of communication network architecture and the flexibility of D2 D communication services,this thesis designs a D2 D communication network architecture based on software defined network(SDN).Through the idea of flattening the network and separating data and control,it divides the communication network into three layers,which are control layer,core layer and access layer,respectively.There are SDN controllers in the control layer which is responsible for scheduling control of the entire network.And D2 D communication controller is one of them whose structure and function this thesis designs and analyzed in detail.In the access layer,it is divided into nine communication modes according to the frequency bands used by D2 D communication,controlled modes,or communication content.Furthermore,seven typical communication modes' signaling and data transmission processes are designed,which provides the framework and support for the theoretical research in the following.There is a deficiency that D2 D resource allocation algorithms are mostly studied in the ideal states of none-users or full-load cell at current stage.So this thesis proposes a more practical system model and divides users into four types according to the state of itself.What's more,a resource allocation algorithm based on service quality is proposed which can expand the range of available channel resource for D2 D users and break the constraint that D2 D pairs can only stay on dedicated or reused mode when they are on data transmission effectively increasing the overall rate of the system.However,when the number of users is large,the user's service quality is no longer a key factor affecting the sum-rate of the system.Therefore,this thesis proposes a resource allocation algorithm based on interference suppression.Under the aforementioned system model,the cellular network is first half-loaded,which is to sacrifice the spectrum utilization to increase the sum-rate of the system;secondly,selecting the user reusing the channel who has minimal interference to the user communicating stably.Through those two steps to maximum sum-rate of the system.This thesis verifies the superiority of the two proposed algorithms through simulation experiments,and comprehensively considering the advantages of the both algorithms,proposes a joint resource allocation algorithm.Compared with other algorithms of the same type,it can effectively improve the sum-rate of the system.Finally,this thesis concludes what the work has been completed,analyzes the current research situation,and forecasts the future research direction.