Research On Data Sharing And Content Caching Technology In Vehicular Named Data Network

As a key element to promote the development of intelligent transportation systems as well as give impetus to the improvement of driving safety and efficiency,intelligent connected vehicles(ICV)have recently attracted more and more attention from community of schol-ars and industry.Due to the fact that vehicle-based wireless communication technology has been widely studied,a series of vehicular service applications,such as driving safety,traffic efficiency improvement,and on-board information service,are spawned in recent years.However,the peculiar characteristics of the ICV system,such as nodes’ high mobil-ity,instability of channel quality,and regional differences of service requests,have brought great challenges to the effective transmission of on-board service data.Many scholars no-ticed that the existing service requesters only care about what kind of data they acquired,instead of who provided the data,a novel architecture,named data networking(NDN),is thereupon introduced in the ICV system,which fits well with the feature of content-oriented in-vehicle service.Although NDN provides an efficient communication mode for the bur-geoning ICV communication network architecture,it still faces various problems: On the one hand,to achieve satisfying system performance on vehicular data communication,the vehicular named data network(VNDN)needs to combine the request characteristics and mo-bile characteristics towards on-board services,and reasonably integrate different on-board communication modes.On the other hand,the improvement of data transmission efficiency in VNDN will largely depend on the formulation of routing and caching strategy.To provide users with better services,the routing and caching of on-board service data needs to consider different application scenarios and types.Aiming at improving the communication efficiency as well as enhancing the quality of user’s experience towards on-board service,this dissertation fully explores the application scenar-ios,service types,user requirements and request characteristics of ICV,finally designs an on-board service data sharing scheme and two caching mechanisms in VNDN.The detailed works are listed as follows:(1)A content sharing mechanism based on matching theory: Targeting to improve the overall benefits of the content sharing system,this proposal first collects the ICV’s data holding and request situation,then takes the matching theory as the modeling tool to build a data sharing scheme based on NDN.In this system,roadside units(RSUs)will first collect and aggre-gate the supply and demand situation of the vehicles within their coverage,and then build the supply-demand matching model based on the transmission characteristics of service re-questors and providers.On the one hand,to avoid high-complexity aggregation procedures in a large-scale vehicular environment,this system groups the vehicles into different clusters based on mobility,and the upload of data requests and holdings will be executed in groups.On the other hand,considering that the vehicle may diffuse false information because of faulty sensors,virus infection,or even for selfish reasons,this system proposes a reputation measurement mechanism into the matching system to encourage the data suppliers to provide positive on-board services.To incite data holders to actively participate in data sharing,the system assumes that the requester will award the node who provides content units.Based on the above aspects,the mechanism customizes utility functions for both data provider and requester to practically improves the overall benefit of the on-board service data sharing sys-tem.(2)A cache offloading mechanism based on Stackelberg game: Consider the situation that if all nodes within the base station’s(BS)coverage initiate service requests will bring high data concurrency to the base station,and the ICV might detect the interference of the data requested by other nodes.Taking the above factors into account,this mechanism is proposed to offload the service data stored in BS to vehicles.When a requester has on-board service data requirements,it can send an interest packet to the surrounding nodes,instead of sending it to BS.In this way,the communication style converts from V2 I to V2 V.Furthermore,to encourage system participants to actively cache service data,the BS will provide a certain incentive award for the node that performs cache offloading.To be specific,the system first designs utility functions for the BS and vehicles,where the vehicle considers the delay re-duction,cache maintenance cost,data transmission cost,and received incentive value,and the BS considers the remaining on-board service communication load,data transmission cost and paid incentive value.Then,the system is modeled as Stackelberg game,based on this,the system cache allocation problem is finally solved with the help of knapsack solution and optimization theory.(3)A heterogeneous caching strategy towards on-board service: Aiming at optimizing the user experience towards on-board services,this work builds an in-network cache strategy,which takes the characteristics of on-board applications and vehicles’ mobility into account,for different carriers in the ICV.The strategy assumes that the on-board service data can be encoded into several sub-units,and these units will be sequentially stored to the vehicle node and the small base stations(SBSs)that are deployed along the roadside.In this strategy,ICV will first try to request data through V2 V communication when they have a service demand and then issue interests to the SBSs.After this phase,a request accessing the remote data source node will be uploaded in case the user cannot get the complete service content.This strategy targets the minimization of users’ waiting time,takes the cache space and power limitation as constraints,and finally realizes the effective improvement of user satisfaction level.