Lightweight opportunistic routing forwarding strategy based on Markov chain

A lightweight opportunistic routing forwarding strategy (MOR) was proposed based on Markov chain.In the scheme,the execute process of network was divided into a plurality of equal time period,and the random encounter state of node in each time period was represented by activity degree.The state sequence of a plurality of continuous time period constitutes a discrete Markov chain.The activity degree of encounter node was estimated by Markov model to predict its state of future time period,which can enhance the accuracy of activity degree estimation.Then,the method of comprehensive evaluating forwarding utility was designed based on the activity degree of node and the average encounter interval.MOR used the utility of node for making a routing forwarding decision.Each node only maintained a state of last time period and a state transition probability matrix,and a vector recording the average encounter interval of nodes.So,the routing forwarding decision algorithm was simple and efficient,low time and space complexity.Furthermore,the method was proposed to set optimal number of the message copy based on multiple factors,which can effectively balance the utilization of network resources.Results show that compared with existing algorithms,MOR algorithm can effectively increase the delivery ratio and reduce the delivery delay,and lower routing overhead ratio.     

Context-adaptive forwarding in mobile opportunistic networks

When two opportunistic network peers encounter, utility functions are generally employed to select the messages that have to be exchanged, with the purpose of maximizing message delivery probability and reduce congestion. These functions compute weighted sums of various parameters, like centrality, similarity, and trust. Most of the existing solutions statically compute the weights based on offline observations and apply the same values regardless of a node’s context. However, mobile networks are not necessarily constant in terms of behavior and characteristics, so the classic approach might not be suitable. The network might be split into sub-networks, which behave differently from each other. Thus, in this paper, we show that, by dynamically adjusting the behavior of a node based on its context, through the adjustment of the utility function on the fly, the opportunistic forwarding process can be improved. We show that nodes behave differently from each other and have different views of the network. Through real-life trace-based simulations, we prove that our solution is feasible and is able to improve an opportunistic network’s performance from the standpoint of hit rate, latency, and delivery cost.     

基于社会特征周期演化的机会移动网络路由转发策略

针对分布式k团社区检测引起的超大社区问题,提出了具有节点退出机制的?-window社区检测方法,相应提出了?-window中心性估计。通过实验发现?-window社区和?-window中心性具有周期演化特性,利用该特性,提出TTL(time to live)社区检测和TTL中心性估计,以更准确预测消息生存期上节点的相遇。随后,利用TTL社区和TTL中心性作为转发测度,设计了新的机会移动网络路由算法PerEvo。实验结果表明,与现有的基于社会特征的路由算法比较,PerEvo在保持基本不变的传输开销的同时,有效提高了机会移动网络消息投递的成功率。 关键词：机会移动网络;社区;中心性;周期演化;消息转发     

A forwarding scheme based on swarm intelligence and percolation centrality in opportunistic networks

Incorporating social relationship properties into forwarding schemes in opportunistic networks has become a more and more important paradigm. Communication among the nodes in an opportunistic network relies on intermittent contacts without complete end-to-end paths. Most of these forwarding schemes take advantage of social information such as contact information and social relationship among the nodes in the network. In this paper, we propose a social information based forwarding scheme in opportunistic networks through mimicking honey bees’ behaviors in an artificial bee colony. In the proposed scheme, we adopt the percolation centrality in the social networks to assign certain nodes as “influential” bees. The proposed forwarding scheme is aim at balancing the level between network traffic and transmission delay using the home-cell community-based mobility model (HCMM). Experiments were performed on the network simulator NS-2. The results show that the proposed scheme has outstanding performance for the level of network traffic and transmission delay in comparison to other schemes such as Epidemic, PRoPHET and SimBet when using the HCMM.     

A trust-based framework for data forwarding in opportunistic networks

In general, the encounter probability is leveraged to evaluate whether a node is a qualified next-hop forwarder in Opportunistic Networks (OppNets); however, it does not truly present the node’s competency of delivering data in a hostile wireless environment, because a malicious node can arbitrarily bloat that probability to intercept data from others. In this paper, we design a trust-based framework to more accurately evaluate an encounter’s delivery competency, which can be flexibly integrated with a large family of existing data forwarding protocols designed for OppNets. As a case study, we integrate our proposed framework with PROPHET, and demonstrate its effectiveness against “black hole” attacks through experimental study.     

带有编码冗余控制的机会网络数据转发机制

网络编码方法能有效提高数据传输效率,但采用该方法的机会网络数据转发机制均未考虑传输中的编码数据迭代冗余副本控制问题。为了充分降低译码复杂度并减少迭代冗余副本,提出了相遇持续时间估计及编码机会感知方法,进而设计了带有传输容量估计的编码冗余控制数据转发机制。节点以分布式的方式感知数据编码机会,为不同扩散程度的数据确定相应的优先级,并根据传输容量估计结果完成转发控制,以充分利用节点间的相遇持续时间。结果表明,所提出机制有效地减少了网络中的冗余副本,使译码所需的数据量趋于理论上的最小值,改善了网络资源利用率。     

基于网络编码的机会网络高效路由算法

针对采用Epidemic机制的机会网络路由算法在数据分组传送阶段存在通信冗余的问题,提出了一种基于网络编码的高效路由算法--NCBER(network-coding-based epidemic routing）。NCBER在传送数据分组的过程中使用主动异或网络编码和多播,并取消了 Request（请求）控制分组,从而减少数据分组的转发次数和控制分组数量,降低网络开销,缩短分组传输时延。理论分析和仿真结果表明,NCBER 算法在网络开销和数据分组端到端时延性能方面优于经典的Epidemic路由算法及其改进算法MRRMR（message redundancy removal of multi-copy routing）,并且使数据传送成功率保持在100%。     

HUBCODE: hub‐based forwarding using network coding in delay tolerant networks

This paper presents an efficient hub‐based message forwarding scheme for people‐centric DTN, wherein hubs (i.e. nodes with high degree distribution) are utilized as message relays. This scheme reduces redundant message transmissions without penalizing delivery ratio, since hubs collectively form a virtual data conduit which reaches most of the nodes. Further, in order to utilize bandwidth efficiently, this approach leverages linear network coding for exchanging messages among hubs. Copyright © 2011 John Wiley & Sons, Ltd.     

基于节点社会特征的机会网络最优发送策略

建立了基于节点社会特征的机会网络信息传输模型,使用庞特里亚金极大值定理求得最优发送策略,该策略服从阈值形式,设停止时间为h,当t < h时,节点以最大概率发送信息,当t > h时,节点停止发送信息。实验表明,该策略优于最优静态策略。进一步分析发现,节点的平均朋友数目越多,最优发送策略的停止时间越小,同时,其性能也越好。     

机会传感器网络中基于优先级的查询分发和处理算法

提出了机会无线传感器网络中一种基于查询优先级的查询分发和处理(PBQ)算法。算法根据用户定义的查询优先级合理选取消息转发的中间节点,并控制查询消息的转发和拷贝量;同时,动态地调整查询消息的优先级,使得查询结果能快速回传到查询发起者并清理网络中查询的残留消息,避免了不必要的消息传输并提高查询处理的整体效用。模拟实验表明PBQ算法能有效提高机会网络中查询处理的成功率,降低查询的开销和时间延迟。     

Poisson's probability‐based Q‐Routing techniques for message forwarding in opportunistic networks

Opportunistic Networks (OppNets) are intermittently connected infrastructure less wireless networks. There is no continuous end‐to‐end connection between the sender and the receiver, and hence nodes follow a store‐carry‐forward mechanism. The routing algorithm is required to be adaptive to the changing topology of the network. In this work, Q‐Routing technique has been used with forwarding probability and incorporated using Poisson's probability for decision making and controlling transmission energy. The algorithm refines the forwarding decision of finding the next suitable hop by exploiting the characteristics of nodes such as daily routines, mobility pattern, etc. In simulations, the performance of PBQ‐Routing is compared with Q‐Routing, Epidemic Routing, PRoPHET (Probabilistic Routing Protocol using History of Encounters and Transitivity), and HBPR (History Based Prediction Routing) for OppNets. The use of Poisson's distribution improves the effectiveness of the probabilistic forwarding decision. The findings show that the delivery probability of PBQ‐Routing almost gets doubled and overhead ratio reduces to half in comparison with that of Q‐Routing when used in OppNets. PBQ‐Routing outperforms other Q‐Routing based algorithms over Poisson's distribution. As there is less replication in case of PBQ‐Routing, it also saves the transmission energy.     

An altruism‐based trust‐dependent message forwarding protocol for opportunistic networks

In opportunistic networks (OppNets), which are characterized by intermittent end‐to‐end connections, the messages are routed in a store‐carry‐and‐forward fashion using the locally inferred knowledge about the behavior of nodes. As such, most OppNets routing protocols use social metrics that are dependent on the nodes' past information. But the participation of nodes in the message forwarding process is not guaranteed without incentivizing them because most nodes are reluctant in sharing their private resources for public uses. In this paper, some socially derived psychological attributes of a node are introduced to ensure their trustworthy participation in the message forwarding process, leading to the design of an altruism‐dependent trust‐based data forwarding mechanism for OppNets (called ATDTN). In this protocol, each node is associated with a dynamically changing altruism value representing its trust in the network, which is used to determine its status with regard to its participation in message forwarding. Through trace‐driven simulations using the ONE simulator, it is shown that ATDTN outperforms IronMan and SimBet protocols for routing in OppNets (respectively, 18% and 48% improvement), in terms of delivery ratio, end‐to‐end delay, overhead count, and average number of hops, under varying buffer size and time‐to‐live.     

基于社会网络洪泛算法的消息队列转发策略设计

随着智慧城市的发展,移动智能终端的普及,社会网络成为研究人员热议的话题。由于洪泛算法在网络投递率、网络延迟方面有着较为突出的表现,文章主要基于社会网络的洪泛算法,设计了MUOB的消息队列转发策略。通过实验结果表明MUOB转发策略在网络投递率、网络延迟方面优于传统的随机转发策略,先进先出转发策略以及最近的Min Hop转发策略。     

基于重复博弈的Ad Hoc网络节点转发策略分析

在无线Ad Hoc网络中,源节点和目的节点互相通信需要中继节点的支持,但节点是理性的,所以可能会拒绝转发请求。这里就节点之间存在的合作问题,对针锋相对策略、冷酷策略、完全合作策略、宽恕的针锋相对策略、严厉针锋相对策略进行了纳什均衡分析。理论分析可知,针锋相对策略相对于其他策略更具优势,因为它的阈值较低。     

Content forwarding strategy based on ICN architecture in VANET

Combining VANET with ICN,a routing building and selecting strategy-SRBS based on vehicular dynamic parameters was proposed.After locating the content nodes through content discovery process,several unicast forwarding paths would be built,which reduces useless traffic compared with a flooding way.By introducing dynamic metrics and LET to routing building and selecting process,SRBS improved the link stability and reliability,which ensured the Data’s successful return.Simulation results show the scheme also improves the time tolerance of routings and makes full use of network cache and reduces delay and routing hops.     

Two-level pointer forwarding strategy for location management in PCS networks

For a IPCS network to effectively deliver services to its mobile users, it must have an efficient way to keep track of the mobile users. The location management fulfills this task through location registration and paging. To reduce the signaling traffic, many schemes such as a local anchor (LA) scheme, per-user caching scheme and pointer forwarding scheme have been proposed in the past. In this paper, we present a new location management scheme which intends to mitigate the signaling traffic as well as reduce the tracking delay in the PCS systems. In this strategy, we choose a set of visitor location registers (VLRs) traversed by users as the mobility agents (MA), which form another level of management in order to make some registration signaling traffic localized. The idea is as follows: instead of always updating to the home location register (HLR), which would become the bottleneck otherwise, many location updates are carried out in the mobility agents. Thus, the two-level pointer forwarding scheme is designed to reduce the signaling traffic: pointers can be set up between VLRs as the traditional pointer forwarding scheme and can also be set up between MAs. The numerical results show that this strategy can significantly reduce the network signaling traffic for users with low CMR without increasing much of the call setup delay.     

一类基于主动网络的网络拥塞控制策略

本文基于主动网络的思想，提出了在保持与传统拥塞控制策略兼容，而又不同于传统通用的“被动”式拥塞控制的“主动”式拥塞控制策略。我们以ＭＰＥＧ这一类在时间上短期和长期都相关的特殊数据流为例，进行了实验验证，其结果表明：我们所提出的主动拥塞解决很好地解决ＭＰＥＧ数据拥塞的问题。同时，也说明了用主动网络的思想来拓展目前的网络体系结构是可行的。     

Video-aware opportunistic network coding over wireless networks

In this paper, we study video streaming over wireless networks with network coding capabilities. We build upon recent work, which demonstrated that network coding can increase throughput over a broadcast medium, by mixing packets from different flows into a single packet, thus increasing the information content per transmission. Our key insight is that, when the transmitted flows are video streams, network codes should be selected so as to maximize not only the network throughput but also the video quality. We propose video-aware opportunistic network coding schemes that take into account both the decodability of network codes by several receivers and the importance and deadlines of video packets. Simulation results show that our schemes significantly improve both video quality and throughput. This work is a first step towards content-aware network coding.     

Routing protocols for underwater wireless sensor networks based on data forwarding: a review

Nowadays, underwater wireless sensor network (UWSN) is an important field for researchers due to its well know applications like seismic monitoring, disaster prevention, offshore exploration, pollution monitoring, oceanography data collection, equipment monitoring, assisted navigation, and tactical surveillance. Many research challenges are available for UWSN; the design of routing protocol is one of them. The majority of the researchers have designed the routing algorithms but still, the data forwarding mechanism needs improvement. The reliable communication between the source and sink nodes is really a complicated task due to the limitation of the acoustic channel, water pressure, and limited bandwidth. This review paper focuses on the problems of those routing protocols which are based on data forwarding. In this review paper, we further present the route development, data forwarding, and route maintenance of the proposed routing protocols. The key aspects of this review article present the limitations and advantages of data forwarding routing protocols. We also present analysis of data forwarding routing protocols with analytical and numerical simulation methods with their critical analysis. This review article helps the researchers to create further research in the field of routing protocols based on data forwarding.     

社会属性感知的间断连接无线网络数据转发策略

间断连接无线网络中的节点具有极强的聚集特性,数据转发过程需要充分地考虑节点之间的社会关系。提出一种社会属性感知的数据分发策略,根据实时获取的多维网络状态参数,节点以分布式的方式估计其自身及其他节点的社会属性。进而确定数据携带节点与目的节点之间的关系,以最小化资源开销的方式实现数据转发。结果表明,与典型机制相比,所提出的数据转发策略具有较高的投递率和较低的延迟,有效地改善了网络性能。