一种适用于空间DTN网络的高效可靠传输方法研究  

An efficient and reliable transmission scheme for space DTN

作　　者：侯冬旭 赵康僆[1] 李文峰[1] Hou Dongxu;Zhao Kanglian;Li Wenfeng(School of Electronic Science and Engineering,Nanjing University,Nanjing,210023,China)

机构地区：[1]南京大学电子科学与工程学院,南京210023

出　　处：《南京大学学报（自然科学版）》2018年第3期522-528,共7页Journal of Nanjing University（Natural Science）

基　　金：国家自然科学基金(61401194)

摘　　要：容迟容断网络(Delay/Disruption Tolerant Network,DTN)可工作于长延时、频繁中断以及非对称速率环境下的特点,使其能匹配卫星等空间节点的通信传输要求,并适应近地空间信息系统组网.在DTN网络中,可通过ARQ(Automatic Repeat reQuest)机制(如LTP红色传输模式)、差错控制编码(如束协议下的差错编码机制)等多种方式来保障数据的可靠传输,但当空间传输条件恶劣(例如链路频繁中断、高误码率等),令传输过程中丢包严重或接收到大量错误包时,将极大降低上述方式的传输效率.为提高传输效率并考虑到DTN覆盖网络协议架构的设计思想,提出应用层信道编码与ARQ机制结合的混合可靠传输方案.一方面,通过在应用层添加信道编码增加纠错能力以减少重传,同时结合ARQ机制,使得在信道条件恶劣、丢包或错包现象严重时,也能收到足够的数据包进行解码,从而提高传输效率;另一方面,基于DTN网络的覆盖网络协议架构,在应用层加入信道编码,可使得该方案兼容下层不同传输协议.仿真实验结果表明,提出的混合方案可以提高DTN下的可靠传输效率,且随着信道条件不断变差,与单纯ARQ方案相比,完成传输所需时间更短、传输效率更高.The characteristic of delay/disruption tolerant networking（DTN）that can work under the transmission conditions including the long propagation delay,frequent link disruptions,channel-rate asymmetry,etc.,enables it to meet the challenges that characterize satellite communications and space internetworking.There are many ways existing in DTN which can guarantee the reliable data delivery,such as Automatic Repeat reQuest（ARQ）,error control coding（ECC）by Bundle protocol layer.However,their transmission efficiency will be greatly reduced under harsh space transmission conditions which result in high loss of data or many error receiving packets.In order to improve the transmission efficiency and without changing the overlay networking architecture of DTN,this paper proposes a hybrid reliable transmission scheme combining the application layer channel coding and ARQ mechanism.On the one hand,the retransmission rounds can be decreased due to the ability of the channel error correcting coding.Meanwhile,with the help of ARQ mechanism,the hybrid scheme can also get enough data packets for decodingunder the severe channel conditions.On the other hand,the proposed hybrid scheme plays a role in the application layer,without changing the overlay networking architecture of DTN,which enables the co-existence of the heterogeneous transmission protocols.The simulation results show that the proposed hybrid scheme can improve the efficiency of reliable transmission in DTN.Compared with the simple ARQ mechanism,when the channel condition gets worse,the hybrid transmission scheme will take shorter and more efficient transmission while the channel condition getting worse.

关 键 词：容迟容断网络 应用层 信道编码 混合方案 

分 类 号：TP302[自动化与计算机技术—计算机系统结构]