Research On The Key Technology Of Data Transmission In Ferry-based Delay Tolerant Networks

DTN (Delay Tolerant Networks) refers to the environments that fail to adhere to the scenario of traditional wired Internet because of various constraints, such as limited energy, small storage, and nodal mobility. This thesis mainly concerns about the data transmission in FDTN (Ferry-based DTN). We propose a secure data transmission scheme for FDTN, explore the key techniques of using network coding and put forward an efficient Network coding-based Transmission Control algorithm (NTC) in DTN, and then evaluate the algorithms through simulation.After give a review of the basic theory of data transmission in DTN and its state-of-the-art techniques, we discuss the features of it in detail and also the architecture of FDTN. Then we give a comprehensive introduction of bundle protocol, routing algorithm and security issues. Also we analyze the security requirements and the key problem of data transmission in FDTN. The basic theory, implementation and the state-of-the-art of using network coding in DTN are also discussed.A secure data transmission scheme named EGS is proposed to meet the security requirements of FDTN. EGS is a group signature-based scheme. It provides a forward security property which makes it easy to deploy in DTN environment. EGS makes ferry carry out more signature verification computation and hence result in the decreasing of the regular node's computation load. It is proved through theoretical analysis that EGS satisfies the basic security requirements and requires lower computation load than other common algorithms. Additional analysis shows that EGS is an efficient security scheme for FDTN.A Network coding-based Transmission Control algorithm named NTC is proposed based on the discussions of the data transmission model and key techniques of using network coding in DTN. By utilizing NTC, a node decides whether to accept a coded message by verifying a summary vector of the message other than requesting the entire message, which greatly reduces the data delivery overhead without influencing the message delivery ratio and therefore implements an efficient data transmission scheme.At last, an experiment environment is designed to simulate the network coding scheme, NTC algorithm, and the selective network coding scheme. As the simulation results showing, exploiting the network coding in DTN gains great improvement in message delivery ratio but introduces high transmission overhead. The NTC algorithm is helpful in reducing the transmission overhead without influencing the message delivery ratio.