Research On Data Forwarding And Storage Mechanism In Named Data Wireless Mobile Ad Hoc Networks

Named Data Networking(NDN)is a new clean-slate architecture for Internet.It has recently been drawing increasing attention in academia as well as industry and is a hot research topic in next generation Internet.The research on applying NDN in wireless mobile ad hoc networks is also gradually carried out,and reflects a number of advantages.However,the research of applying NDN in wireless mobile ad hoc networks has just started,and many problems need to be solved urgently.Efficient content retrieval is the original intention of NDN design.It is very challenging to apply NDN in wireless mobile ad hoc networks to achieve efficient content retrieval for high success ratio of content retrieval,low delay and low overhead.Data forwarding and storage mechanisms are two key issues in achieving efficient content retrieval for named data wireless mobile ad hoc networks.How to design effective data forwarding protocol and storage mechanism,and better serve the content retrieval in the named wireless mobile ad hoc networks,which brings many new challenges.There are two kinds of network environments in the wireless mobile ad hoc networks.One is the Mobile Ad hoc Networks(MANET),which is mainly connected,and the network is sometimes divided into different subnets.The other is the Delay Tolerant Network(DTN),in which the network is intermittent and the node meets other nodes occasionally.And according to the storage space of the node in the network,it can be divided into two networks:the network in which storage space of the node is not limited and the network in which storage space of the node is limited.This dissertation investigates the data forwarding protocol under the Naming Data MANET(NDMANET)and the Named Data DTN(NDDTN),as well as the storage mechanism under storage space limited NDMANET.Therefore,in this dissertation,we first consider the design problem of data forwarding protocol in the environment of NDMANET,in which the node's distribution and movement are unrestricted.Then,we further consider the design problem of data forwarding protocol under NDDTN with random node movement.Finally,we consider the storage mechanism design issues in storage space limited NDMANET.Ultimately,we can achieve efficient content retrieval in the named data wireless mobile ad hoc networks.The innovative achievements of the dissertation are as follows:1.A Greedy and Neighbor Aware data forwarding protocol(GNA)in NDMANET is proposed.The node furthest from the previous hop node is chosen as a forwarding node by greedy method to maximize the single-hop transmission distance,reduce the number of forwarding hops.The neighbor aware method is adopted to increase the number of forwarders and expand the scope of message transmission,so the success rate of content retrieval is improved.The Bloom filter-based mapping method is used to reduce the size of the neighbor information tables exchanged between the neighbor nodes and simplify the transmission of neighbor information.The simulation results show that,compared with the greedy forwarding protocol,the GNA protocol can increase the success ratio of content retrieval by about 50%at the lower node density,and increase a certain amount of network overhead;the transmission delay in GNA protocol is similar as the greedy forwarding protocol.The advantage of the GNA protocol is that it can achieve higher success ratio of content retrieval in an environment where the nodes move freely?2.An Activeness-based Data Forwarding protocol(ADF)in NDDTN is proposed.The neighbor information of the node and the local activeness list are maintained by periodically broadcasting Hello messages.The node's activeness enhancement and attenuation algorithm is given in consideration of the number of nodes encountered at different times.The forwarder selection mechanism is given,and the node with higher activeness is selected to forward the Interest packets or Data packets,which effectively reduces the communication overhead.The simulation results show that the ADF protocol can effectively reduce the'transmission delay and reduce the network overhead while acquiring the similar success rate compared to the Epidemic protocol in the case of larger data packet when the real movement trajectory data is used in our experiment.3.The space-limited optimized storage protocol in NDMANET(SLAMS)is proposed.The data availability is improved by using the mechanism of maintaining K copies for each data.Considering the network topology of MANET changes frequently,a distributed method is used to maintain the copy of the data in the network.The method based on the waiting clock to select the data to be maintained is used to realize the asynchronism of the copy maintenance.Considering the limited storage space of the mobile node,data copies are stored into nodes with larger free strorage space,which can avoid data loss caused by deleting the old data for storing the new data,and which leads to reduce the convergence time of data copy maintainance.The simulation results show that,compared with current major solution Phoenix,the data lost rate can be reduced by up to 50%,the time of convergence can be reduced,and overhead of data block storage can be reduced in our SLAMS protocol.Besides,the SLAMS protocol could effectively increase the probability of K copies for each data block in case that mobile nodes have limited storage space.