Research Of Transmission Protocol In Delay Tolerant Network

Delay Tolerant Network (DTN) is a network architecture that can communicate effectively in a limited network environment. It can ensure communication for users in a heterogeneous network characterized by long delay, high bit error rate, frequent interruptions and other features of connection and satisfy the needs of establishing an interconnection network in a complex environment. Link resources are restricted in limited communication environment, how to make efficient improvement of link utilization and improve transmission reliability is a research area of concern in DTN architecture.This paper is supported by The National 863 Project:Key Technologies and Demonstrations of Future Integrated Network (NO.SQ2015AA0101106). It shows experimental performance evaluation of DTN convergence layer adapter protocols, focuses on the research of Licklider Transmission Protocol (LTP) interactive mechanism and transport model.This paper first introduces the DTN architecture, DTN bundle layer protocol and major convergence layer adapter protocols:Bundle Protocol (BP), LTP protocol, TCP Convergence-Layer Protocol (TCPCL), UDP Convergence-Layer Protocol (UDPCL). Then it establishes a deep space Earth-Moon communication scenario via Satellite Tool Kit (STK), and present performance evaluation in the Earth-Moon communication scenario of LTP architecture, TCPCL architecture and TCPCL/LTP hybrid architecture respectively in deep space link simulator designed by the laboratory. Then the paper analyzes the main reasons of throughput performance differences for three architectures and completed performance evaluation of LTP architecture and TCPCL architecture in single hop communication and of different LTP aggregation mechanism, detailed analyzes difference of aggregation mechanism between LTP and TCPCL from design principles, and obtained the trend of throughput performance under different LTP aggregation mechanism.Finally, this paper build optimal transmission efficiency model, transmission cost model and delivery delay model in non-symmetric uplink and downlink channel conditions for LTP based on link bandwidth utilization, effective data transmission ratio and data delivery time and then make experimental comparison. Combined with LTP protocol transmission models and protocol architecture performance evaluation, we design the configuration scheme of LTP protocol in Earth-Moon communication scenario and LTP configuration interface in Linux operating system. The experimental comparisons prove that transmission model built in this paper can accord with the experimental results in the conventional channel and severe channel which has large aggregation size, the LTP transmission models also have referenced significance on DTN transmission experiments.