The Research Of Content Transmission Mechanism And The Construction Of Simulation Platform In Heterogeneous Cellular Network

With the rapid development of mobile wireless communication technologies,mobile user devices grow explosively and users' data demand increases exponentially.Traditional cellular network could not meet the wireless communication requirements.Deploying small cells and D2D devices in traditional cellular networks results in heterogeneous cellular networks(HCNs),which could improve system capacity and extend range of coverage.Therefore,HCNs have broad prospects and arouse the researchers' attention.HCNs with cache-enabled D2D nodes and small cells base stations can serve user locally and then decrease the backhaul data traffic by caching popular content in access networks.At the same time,it may bring several problems,such as optimal deployment,interference management,user access and resource allocation.So how to choose a reasonable and efficient content transmission mechanism and resource allocation strategy is an interesting problem.Furthermore,the simulation platform of this scenario is an important way to verify the relative algorithms performance.It also needs further research.In view of the above problems,this thesis studies the content transmission mechanism in heterogeneous cellular network and the construction of simulation platform.A cache-based content transmission mechanism is proposed.The user's intimacy model is established according to the users social relations including the user's friend relationship,the resource requests similarity,and the user's contact frequency.According to the intimacy model,the user and the base station are grouped according to the social situation,and then respective cache are determined.The content transmission selection mechanism and frequency allocation are proposed.This is modeled as a mixed integer nonlinear programming problem,and particle swarm optimization is used to solve it.The simulation results show that the proposed algorithm can effectively reduce the system latency and achieve higher user data rate than existing algorithm.OMNeT++ is used to build a network simulation platform for content transmission mechanism in HCNs.Due to the lack of existing open source in OMNeT++,it needs further design and study to set up the platform.The design goals and framework of the platform are proposed.The network entities nodes are realized with the caching ability.The content transmission mechanism and switch functions are also designed and realized.Meanwhile,the channel models are realized including outdoor plaza scene,shopping mall scene and residential building scene,as well as the mobile model for shopping mall scene and indoor office scene.Simulation results are collected and analyzed with end-to-end delay and throughput.