A Study About Contact Frequency And Time-based Data Forwarding Algorithm In Delay Tolerant Networks

Delay Tolerant Networks(DTNs)is a new type of network system known for its intermittently connectivity,and mobile social networks(MSNets)is an important application of DTNs.In MSNets,the packet is propagated through the intermittently connectivity which is established when two human-carried wireless-enabled devices are within communication range of each other.With the popularity of smart device,MSNets will cover more and more people.The information plays an irreplaceable role today,and how to collect useful information effectively is one of the modern talents and skills.Therefore,the data forwarding algorithm is one of the key problems in MSNets.First,this thesis investigates the development of mobile social networks,the basic characteristics of mobile social networks' users,several common types of mobile social networks and several typical data forwarding algorithms.Then,the thesis introduces the preliminary knowledge of point estimation concept and point estimate property and the method of point estimation,In view of contacts made by the nodes,a contact frequency and time ratio-based data forwarding(CFTDF)algorithm is proposed in delay tolerant networks.Its main idea is to predict the future contact frequency and time ratio between two nodes based on their historic encounters,define the activity between nodes based on their contact frequency and time ratio,and determine whether or not a node as a relay node by the activities with the destination of the encounter nodes.The experimental results show that compared with Epidemic algorithm,the proposed CFTDF algorithm can obviously reduce the number of copies,and compared with the PIF algorithm,the proposed CFTDF algorithm can reduce the delivery delay and the number of copies.