An Opportunistic Network Communication Protocol Based On Trajectory Prediction

With the rapid development of the Internet of Things,Intelligent Traffic System(ITS)and V2 V technologies have been widely used.Based on this,the concept of Opportunistic Networks(ONs)has been proposed,which makes it possible to communicate in a sparse environment,and makes it convenient to communicate between users.Compared with the traditional TCP/IP network,ONs does not have high requirements for network environment,even does not need to establish a complete communication link between the source and destination of the message.Communication protocols have always been the research focus of ONs.In ONs,nodes' position change frequently for moving at high speeds,and their communication range is fixed resulting in spotty network connections,which cannot meet the requirements of conventional TCP/IP networks for complete communication links.Therefore,how to achieve efficient delivery in such a complex and changing network environment is the focus of the ONs communication protocol research.According to the characteristics of ONs and the design requirements of communication protocols,this paper proposes a Social Trajectory Prediction based on Region Division(STPRD)method,which predicts the node trajectory based on the historical movement trajectory data and the sociality of the node.First,the conditional entropy of node positions is used to analyze the predictability of node trajectory to provide a basis for node trajectory prediction.Then,the urban roads are divided according to the grid.The activity area of the node is divided into a circle,where the node's current location is the center and the product of speed and prediction unit is the radius.Finally,the predicted trajectory of the node is formed by its predicted position,which is determined based on the probability calculated by the historical data and socially of the node.Based on the STPRD prediction method,this paper further designs a Trajectory-Prediction Based Opportunistic Routing Protocol(TPBOR).First,the source node designs the ideal message delivery path based on the predicted node trajectory and embeds it into the message pocket header.Then,the relay nodes are selected to delivery message by the node's own resources(energy,cache)and activity and the correlation between the node's actual trajectory and the ideal path.The TPBOR protocol dynamically allocates the number of copies and uses the priority ordering method to complete delivery during the message delivery phase,which can make full use of the node resources,strive for the maximized message delivery and reduce the average delivery latency.The TPBOR protocol achieves a balance between the delivery ratio and the average delivery latency to improve the communication performance.Finally,based on the Opportunistic Network Environment Simulator(ONE),the TPBOR protocol is achieved and the simulation experiment is carried on to analyze and compare with four classic communication protocols,such as TDOR,Sim Bet,Prophet,EA-Prophet.Analyzing the simulation results,under the same conditions,the TPBOR protocol has higher stability,achieves a higher messages delivery ratio and a lower average delivery latency,and achieves the purpose of efficient delivery while reducing the delay.