Network Coding for Overhead Reduction in Delay Tolerant Networks

Employing Network Coding (NC) in routing protocols for Delay Tolerant Networks (DTNs) is a challenging issue during the last years due to its potential beneficial effect on improving relevant critical metrics. This paper proposes an effective NC scheme intended for sparse DTNs comprising nodes of limited storage capacity. The scheme employs a memory management algorithm that makes optimal use of the limited storage capacity and focuses on unicast sessions where source and intermediate nodes combine only packets belonging to the same generation and destined for the same destination node. Upon having received a sufficient number of linearly independent packets resulting in a matrix of full rank, the destination nodes can apply network decoding to retrieve the information intended for them. The proposed scheme is fully distributed since the network nodes make decisions based on information collected solely from their own buffers. Combined either with Epidemic or probabilistic routing protocols, the scheme manages to drastically reduce the overhead created per source packet.     

Trust based Intelligent Routing Algorithm for Delay Tolerant Network using Artificial Neural Network

In today’s world, when every mobile device corresponds with human behavioral patterns. People often come across with various communities having patterns such as mobility, communication and groups. Trust is an intrinsic factor, which plays important role in formation of such communities. It is important to see the inherent risk involved in such socially active communities. Such factors motivate the use of trust as a routing factor in Delay Tolerant Networks (DTNs). This paper proposes a Trust based Intelligent Routing Algorithm, which exploits the Call Data Record from Call Detail Record. The function of Artificial Neural Network is to calculate and learn, trust value that can be shared among network devices. Our algorithm lowers the need of nodes resources like energy consumption, computation time and space overheads. The proposed algorithm enhances the routing performance in DTN. The earlier work claiming better efficiency generally ends up consuming network’s resources. On the contrary our proposed algorithm provides in-built security, without any additional overhead. To the best of our knowledge the proposed work is the first of its kind, providing ingrained security feature to the DTN. This work gives vantage point to the researchers in the field over other schemes proposed in the past.     

A Quantized Delay Buffer Model for Single-Wavelength Fiber Delay Line Buffer

The fiber delay line (FDL) buffer is widely used in optical packet switching networks for contention solution. In this paper, a quantized delay buffer model is proposed to analyze the performance of the single-wavelength FDL buffer. Considering the delay quantization in the FDLs, the delay time and the waiting time of the packet are discussed. Without specific assumptions of the packet arrival process and length distribution, the model presents a generic approach to study the delay time distribution and modify the integral equation for the waiting time distribution. Analytic and exact results of the two aforementioned distributions can be obtained without any approximation. The accuracy of the model is validated through simulation.     

Integrated Social and QoS Trust-Based Routing in Delay Tolerant Networks

We propose and analyze a class of integrated social and quality of service (QoS) trust-based routing protocols in mobile ad-hoc delay tolerant networks. The underlying idea is to incorporate trust evaluation in the routing protocol, considering not only QoS trust properties but also social trust properties to evaluate other nodes encountered. We prove that our protocol is resilient against bad-mouthing, good-mouthing and whitewashing attacks performed by malicious nodes. By utilizing a stochastic Petri net model describing a delay tolerant network consisting of heterogeneous mobile nodes with vastly different social and networking behaviors, we analyze the performance characteristics of trust-based routing protocols in terms of message delivery ratio, message delay, and message overhead against connectivity-based, epidemic and PROPHET routing protocols. The results indicate that our trust-based routing protocols outperform PROPHET and can approach the ideal performance obtainable by epidemic routing in delivery ratio and message delay, without incurring high message overhead. Further, integrated social and QoS trust-based protocols can effectively trade off message delay for a significant gain in message delivery ratio and message overhead over traditional connectivity-based routing protocols.     

一种基于能量感知的延迟容忍移动无线传感器网络多拷贝路由协议(英文)

The two-phase replication-based routing has great prospects for Delay Tolerant Mobile Sensor Network (DTMSN) with its advantage of high message delivery ratio, but the blind spraying and the low efficiency forwarding algorithm directly influences the overall network performance. Considering the characteristic of the constrained energy and storage resources of sensors, we propose a novel two-phase multi-replica routing for DTMSN, called Energy-Aware Sociality-Based Spray and Search Routing (ESR), which imple...     

延迟容忍网络状态感知的路由策略研究

延迟容忍网络具有间歇连通的特点,这为数据传输提出了很大的挑战。目前的路由算法没有充分考虑节点的整个状态(位置、速度),该文提出了一种节点状态感知的路由策略SARM(Situation-Aware Routing Method)。SARM根据节点的状态估计它能把消息传送到汇聚节点的可能性,并把消息复制到那些比自身可能性大的节点上。该文根据消息的生存时间、剩余时间及复制次数提出了一种消息队列管理机制。仿真实验表明,SARM在不增加消息副本数量的情况下提高了传输成功率并降低了传输延迟。     

Energy Efficient Inactive Node Detection Based Routing Protocol for Delay Tolerant Network

Wireless Personal Communications - The delay tolerant network multi-copy protocols create and transmit multiple copies of each message that overload the buffer size, energy and bandwidth. The...     

基于位置信息的仓储容迟网络路由算法

仓储网络接入环境适合使用容迟网络(DTN)协议,然而渡轮的计划移动有时间的概率不确定性,从而导致DTN路由算法的先验知识计算复杂.本文提出基于位置信息的路由算法,由接入基站参数矩阵决定接入路由器集合,使用广义k任播缓解流量爆炸问题,最终使用效用最大化的规划模型,在整个许可时间段和k个路由器之间进行路由和资源分配,结合DTN的托管传送,可以实现对多个目的地同时传送数据分组.仿真结果表明,其传输性能和顽健性整体较优,能更灵活地支持仓储容迟网络拓扑结构的变化.     

基于位置的开放式容迟网络路由算法

移动环境下互联网接入网络频繁中断,需使用容迟网络协议.然而时间概率不确定性导致DTN路由算法的先验知识计算复杂,文中提出基于空间的路由算法以消除.进一步由接入路由器信息矩阵决定实现接入路由器的k集合,提出广义k选播以缓解概率不确定性,使用效用最大化的规划模型,在整个许可时间段和k个路由器之间进行路由和资源分配,结合DTN的托管传送,可以对多个目的地同时传送数据包.仿真验证了传输性能和鲁棒性整体较优,能灵活支持开放式网络拓扑结构变化.     

接入网综合网管对策

本文通过分析接入网网管特点和应用现状,提出了采用基于Intranet/Web进行接入网综合管理的分布式管理模式,讨论了其特点,最后介绍了标准化和应用进展。     

Message Drop Control Buffer Management Policy for DTN Routing Protocols

In delay tolerant network interruptions will occur continuously because there is no end-to-end path exists for the longer period of time from source to destination. In this context, delays can be immensely large due to its environment contrails e.g. wildlife tracking, sensor network, deep space and ocean networks. Furthermore, larger replication of messages put into the network is to increase delivery probability. Due to this high buffer occupancy storage space and replication result in a huge overhead on the network. Consequently, well-ordered intelligent message control buffer drop policies are necessary to operate on buffer that allows control on messages drop when the node buffers are near to overflow. In this paper, we propose an efficient buffer management policy which is called message drop control source relay (MDC-SR) for delay tolerant routing protocols. We also illustrate that conventional buffer management policy like Drop oldest, LIFO and MOFO be ineffective to consider all appropriate information in this framework. The proposed MDC-SR buffer policy controls the message drop while at the same time maximizes the delivery probability and buffer time average and reduces the message relay, drop and hop count in the reasonable amount. Using simulations support on an imitation mobility models Shortest Path Map Based Movement and Map Route Movements, we show that our drop buffer management MDC-SR with random message sizes performs better as compared to existing MOFO, LIFO and DOA.     

光分组交换网络中光纤延迟线缓存技术

光分组交换网是全光网络发展的必然趋势.然而,光分组交换网络发展的瓶颈是光缓存技术.目前,在光域比较现实的还是采用光纤延迟线(FDL)作光缓存.重点研究了光纤延迟线光缓存技术,对FDL光缓存技术进行了深入的分析和归纳,并对每一种光纤延迟线光缓存调度策略的优缺点都进行了细致的分析.最后指出了光纤延迟线光缓存技术的未来研究重点和发展方向.     

Low overhead spatiotemporal video compression over smartphone based Delay Tolerant Network

In this paper we provide a lightweight video compression scheme, Low Overhead Spatio-Temporal Video compression (Lost-Vision) scheme which is done through inter-frame and intra-frame compression. In inter-frame compression redundant frames are removed by a proposed interpolation search-based method and a lightweight edge detection technique. Then intra-frame compression is done by a proposed adaptive column dropping technique modifying an existing technique namely ICCD. At the receiver end, we propose two reconstruction filters targeting to improve reconstruction quality. Performance of our scheme in terms of energy efficiency and reconstruction quality is evaluated both theoretically and practically. In practical implementation, the proposed video compression scheme is assessed in a real environment with different terrains using a smartphones/tablet-based DTN-like network. A Comparison of our scheme with three recent works on video compression shows our scheme's dominance over the competing works with 52%, 45.6% and 53% energy in saving yet maintaining acceptable reconstruction quality.     

容迟网络中基于社会感知的协作机制研究

针对节点的社会自私性(social selfishness)对容迟网络(delay tolerant network,DTN)中路由效率、网络性能和安全等造成的负面影响,采用社会感知(socially aware)、博弈论等方法设计合理的协作机制是当前容迟网络研究的一个重要方向.文中首先描述了节点的社会自私性对容迟网络性能的影响.依据分析工具的差异,将已有容迟网络中基于社会感知的协作机制分为基于博弈论、基于信誉、基于虚拟银行3类.文中对各类协作机制的基本原理、方法和不足之处进行了分析和比较,最后对容迟网络中基于社会感知的协作机制的未来研究方向进行了展望.     

Integrated Network Management System for CSL

CSL is a subsidiary of Australia's Telstra Corporation and is the biggest mobile operator in Hong Kong. In March 2008,CSL contracted ZTE to evolve its existing mobile network into a new all-IP mobile network. To reduce the high Operating Expense (OPEX) of network operation and maintenance,CSL sought an Integrated Network Management System (INMS) to consolidate alarms from various network segments,and to improve network operation and maintenance efficiency. ZTE provided CSL with an integrated network solutio...     

Determination of Relay Node Based on Fuzzy Logic in Delay Tolerant Network

Wireless Personal Communications - Delay tolerant networks are among mobile ad hoc networks. There is not a complete and connected route between the source and destination in these networks due to...     

Energy Efficient Energy Hole Repelling (EEEHR) Algorithm for Delay Tolerant Wireless Sensor Network

Reducing energy consumption and increasing network lifetime are the major concerns in Wireless Sensor Network (WSN). Increase in network lifetime reduces the frequency of recharging and replacing batteries of the sensor node. The key factors influencing energy consumption are distance and number of bits transmitted inside the network. The problem of energy hole and hotspot inside the network make neighbouring nodes unusable even if the node is efficient for data transmission. Energy Efficient Energy Hole Repelling (EEEHR) routing algorithm is developed to solve the problem. Smaller clusters are formed near the sink and clusters of larger size are made with nodes far from the sink. This methodology promotes equal sharing of load repelling energy hole and hotspot issues. The opportunity of being a Cluster Head (CH) is given to a node with high residual energy, very low intra cluster distance in case of nodes far away from the sink and very low CH to sink distance for the nodes one hop from the sink. The proposed algorithm is compared with LEACH, LEACH-C and SEP routing protocol to prove its novel working. The proposed EEEHR routing algorithm provides improved lifetime, throughput and less packet drop. The proposed algorithm also reduces energy hole and hotspot problem in the network.     

容迟／容断网络路由技术研究

容迟／容断网络（DTN）由于其长延迟、高误码率及频繁断路等网络特性不满足互联网较短传输延迟、低误码率及存在端到端路径的基本假设,传统Internet体系结构和协议无法直接用于DTN。DTN路由机制可以按照连接的确定性分为确定性路由和随机性路由。确定性路由主要有基于树的路由、时空路由和修正的最短路径路由等方法;随机性路由主要有流行性路由、基于历史消息的路由、基于模型的路由、可控移动路由和基于编码的路由。DTN在游牧计算、军事战场通信、紧急营救及灾后重建方面具有广泛应用前景。     

Performance Evaluation of a Power Management Scheme for Disruption Tolerant Network

Disruption tolerant network (DTN) is characterized by frequent partitions and intermittent connectivity. Power management issue in such networks is challenging. Existing power management schemes for wireless networks cannot be directly applied to DTNs because they assume the networks are well-connected. Since the network connectivity opportunities are rare, any power management scheme deployed in DTNs should not worsen the existing network connectivity. In this paper, we design a power management scheme called context-aware power management scheme (CAPM) for DTNs. Our CAPM scheme has an adaptive on period feature that allows it to achieve high delivery ratio and low delivery latency when used with Prophet, a recently proposed DTN routing scheme. Via simulations, we evaluate the performance of the CAPM scheme when used with the Prophet routing scheme in different scenarios e.g. different traffic load, node speeds and sleep patterns. Our evaluation results indicate that the CAPM scheme is very promising in providing energy saving (as high as 80%) without degrading much the data delivery performance.     

Adaptive Spraying for Routing in Delay Tolerant Networks

Message delivery in Delay Tolerant Networks (DTNs) is challenging due to the fact that the network is intermittently connected. Mobility can be exploited to improve DTN performance. In this paper, we propose a DTN routing scheme Adaptive Spraying. Adaptive Spraying exploits mobility pattern and encounter history to predict the number of nodes with no copy a node will encounter within the expected delay. The number of nodes encountered can be viewed as the number of copies disseminated. Each node with copies dynamically chooses the number of copies by itself, instead of a fixed number determined at the source node. We present an analysis of the scheme and validate the analytical results with simulations. Simulation results show that Adaptive Spraying performs well over a variety of environmental conditions such as transmission range and traffic load.