Research On Data Delivery And Content Sharing Mechanisms In Wireless Ad Hoc

rious mobile applications and the rapid growth of the demand for Internet information anytime and anywhere,wireless ad hoc networks(MANETs)has become the development trend in future network.MANETs have been widely deployed in different application fields,including local service,wireless mesh network(WMN),wireless sensor networks(WSN),Device-to-Device communications(D2D)and vehicle ad hoc networks(VANETs).As the foundation for wireless ad-hoc network implementation and application,the designing data delivery and content sharing mechanisms have been two key research problems,which has been highly focused by the academic and industry.However,because of the user mobility,the instability of the wireless transmission medium,the limited device energy and cache space,random equipment failure,complex service content,and various quality of service requirements and the user selfishness in the MANETs,mass data delivery and content sharing in the MANETs has faced a lot of technical challenges.In view of the characteristics of MANETs and the requirements of potential applications performance,we aim to optimize the data delivery and content sharing performance,study on topology control for data delivery,QoS routing for energy-saving,and D2D-based content sharing,and propose the network topology control model based on complex network theory,the ant colony optimization(ACO)algorithm based energy-saving QoS routing scheme,the ACO-based green energy assisted wireless backhaul routing scheme,and the locality-based content caching policy.Besides,we analyze the influence of user mobility on the performance of content sharing.Research results in the dissertation consolidate the theoretical basis for the deployment,implementation,and application of MANETs.The main contributions are as follows:First,aiming at the problem that the impacts of the dynamic topology on the performance of data delivery and content sharing,we study the network topology control model based on complex network theory to optimize network topology,improve network data delivery performance and extend network lifetime.Firstly,considering the coupling relationship between the user mobility,limited equipment energy,time-varying spectrum and the number of nodes and edges in network topology,we propose a topology control model with preference and anti-preference.Then,the network degree distribution is derived through the mean field theory.Finally,the performance of the network is evaluated in view of the degree distribution,the connectivity correlation,the clustering coefficient and the average path length,respectively.Simulation results show that the proposed topology control model can effectively improve network data delivery performance,balance node energy consumption and load,and decrease network energy consumption.Second,aiming at the problem of fast and reliable multi-hop data delivery in the MANETs,we study the QoS routing mechanism for energy saving.For the mobile ad hoc network,considering the user mobility,the queue length and the residual energy of devices,we propose an energy-efficient QoS routing mechanism based on ant colony algorithm to improve the data delivery rate and reduce the network energy consumption.Simulation results show that under the constraint condition of packet loss ratio and end-to-end delay,the proposed routing mechanism can effectively reduce the average network energy consumption,avoid node congestion as well as balance the transmission rate and delay.For the green energy harvesting aided wireless Mesh backhaul network,considering the time-varying wireless channel condition,the random green energy harvesting,the unknown backhaul traffic flow and the limited node energy,we propose a wireless mesh backhaul routing mechanism based on ant colony algorithm to optimize backhaul data delivery rate and green energy utilization.Simulation results show that under the constraints of maximum power grid power,spectrum resources,and the harvested green energy,the proposed strategy can improve the data delivery rate,the average end-to-end delay,the green energy utilization,and spectrum efficiency.Thirdly,aiming at the problem of the fast and accurate content fetching in the D2D-based content sharing networks,we study on the content caching mechanism and analyze the tempo-spatial limits of D2D-based content sharing considering the impacts of user mobility.Firstly,we study the statistical characteristics of content popularity,user request,and device contact patterns by analyzing traces from realistic networks.Then,based on the results of trace analysis,we propose a locality-based caching model to improve the content sharing hit ratio.Furthermore,we analyze the influences of user mobility on content sharing by defining and derive the theoretical expressions of service lifetime,service distance and recover delay.Finally,the theoretical analysis results are verified by numerical simulation.Simulation results show that the proposed caching mechanism can reduce the device cache usage by 10%to 30%while ensuring the content sharing hit ratio in comparison with the Zipf-based caching policy.Besides,theoretical analysis and numerical simulation results not only analyze and evaluate the device cache usage,content sharing hit ratio,service lifetime,service distance,service recovery delay and network traffic offloading but also provide important theoretical guidance for the design of D2D-based content sharing mechanism.