Research On D2D Mode Selection And Resource Allocation Scheme For Heterogeneous Cloud Radio Access Networks

With the development of wireless communication,the number of mobile terminal users and the demand for wireless access increase rapidly.However,the limited spectrum resources limit the development of wireless communication.To meet the demand,as the key technologies of 5G,Heterogeneous Cloud Radio Access Network(H-CRAN)and D2 D communication(Device to Device)have been widely investigataed.In detail,H-CRAN realizes the compatibility of cloud wireless access network and heterogeneous network.Also,by introducing cloud computing technology into heterogeneous network to achieve large-scale cooperative signal processing,H-CRAN can overcome the shortcomings of the two networks,integrates the advantages of the two networks,and improves the spectral efficiency.The characteristic of D2 D communication technology is that in a certain distance,users can communicate directly without the requirement of base station transmission,which improves the utilization of spectrum resources.Due to the restriction of forward link between distributed remote Radio Head(RRH)and Base Band Unit Pool(BBU Pool)in H-CRAN network,the overall performance of H-CRAN network degrads.In this paper,we use D2 D communication technology to reduce the load of RRH,alleviate the pressure of forward link,and increase the spectral efficiency and energy efficiency of H-CRAN network.The main work and innovations of this paper can be summarized as follows:1.For the scenario of RRH upstream resource reuse in D2 D communication H-CRAN network,The idea of joint design of shared mode selection and resource allocation scheme is proposed.Based on this idea,a joint optimization problem of channel and power allocation scheme is constructed,aiming at D2 D sum rate maximization.Firstly,the shared mode selection is determined according to the channel gain ratio in D2 D communication,and then the optimal channel allocation is carried out based on greedy algorithm.On this basis,three possible shared modes(dedicated channel,multiplexing channel and cellular channel)are optimized by using genetic algorithm,dichotomy method and Lagrange multiplier method,respectively.The simulation results show that the proposed scheme can effectively improve the utilization of RRH cell spectrum resources and reduce energy consumption.2.For multi-user D2 D scenarios,to further improve multiplexing gain,a user clustering scheme is proposed with interference threshold method.With this method,a joint optimization framework of channel and power allocation is built.In detail,D2 D users are clustered ccording to the interference between D2 D users firstly,with an emphasis on minimizing the interference among D2 D users in the same cluster.Then,the graph coloring theory is applied to D2 D users for user clustering.Under the requirement of quality of service(QoS)for D2 D users and cellular users,a resource allocation model based on D2 D users and rate maximization is established.Finally,a power allocation scheme among the clustered D2 D users is built by dichotomy.Simulation results show that the proposed D2 D resource allocation scheme can significantly improve the spectral efficiency of the system.