机会网络自私节点的Bertrand博弈与激励机制研究

在真实的网络环境中,很多节点可能是自私的,它们不愿意牺牲自己的资源为其他节点转发消息。针对这种情况,提出一种基于博弈论的激励机制,可以激励节点与其他节点相互合作。该机制为二阶段激励,激励节点接收消息以协助其他节点转发,同时激励节点转发更多的消息。把源节点与中继节点之间的竞争与合作模型化为Bertrand（伯特兰德）博弈,定义了源节点和中继节点的效用函数。求解了源节点的最佳定价策略和中继节点最佳的转发计划,验证了源节点与中继节点之间存在唯一的纳什均衡。模拟仿真结果表明提出的激励机制能够鼓励自私节点参与合作,能提高路由算法的传递率,同时降低了消息传递延迟。与基于声誉的激励机制相比,所提激励机制能使消息传递成功率提高31.4%、平均时延降低9.7%。     

无线多跳网络中基于博弈论的协作激励机制研究

无线多跳网络中网络传输性能容易受到自私节点的影响。本文首先对目前的节点协作激励机制进行了总结,然后,针对分簇路由中簇间路由场景,运用博弈论中非合作博弈的思想,建立博弈模型以激励簇内节点通过协作通信的方式帮助簇头进行数据包的转发,最后给出了基于非合作博弈的激励机制中纳什均衡解的求解过程。     

On improving the efficiency of truthful routing in MANETs with selfish nodes

In Mobile Ad Hoc Networks (MANETs), nodes depend upon each other for routing and forwarding packets. However, nodes belonging to independent authorities in MANETs may behave selfishly and may not forward packets to save battery and other resources. To stimulate cooperation, nodes are rewarded for their forwarding service. Since nodes spend different cost to forward packets, it is desirable to reimburse nodes according to their cost so that nodes get incentive while the least total payment is charged to the sender. However, to maximize their utility, nodes may tell lie about their cost. This poses the requirement of truthful protocols, which maximizes the utility of nodes only when they declare their true cost. Anderegg and Eidenbenz recently proposed a truthful routing protocol, named ad hoc-VCG. This protocol incurs the route discovery overhead of O(n³), where n is the number of nodes in the network. This routing overhead is likely to become prohibitively large as the network size grows. Moreover, it leads to low network performance due to congestion and interference. We present a low-overhead truthful routing protocol for route discovery in MANETs with selfish nodes by applying mechanism design. The protocol, named LOTTO (Low Overhead Truthful rouTing prOtocol), finds a least cost path for data forwarding with a lower routing overhead of O(n²). We conduct an extensive simulation study to evaluate the performance of our protocol and compare it with ad hoc-VCG. Simulation results show that our protocol provides a much higher packet delivery ratio, generates much lower overhead and has much lower end-to-end delay.     

无线传感器网络入侵检测的重复博弈建模研究

通过分析无线传感器网络节点影响网络可用性及其整体性能的自私行为,提出了一种无线传感器网络入侵检测的重复博弈模型,集中于检测和响应传感器节点的自私行为以加强网络节点的协作性能,利用节点与其邻居节点进行的重复博弈过程,广播节点的效用变化,即时检测出网络节点的自私行为。通过对网络节点的自私行为引入惩戒机制,从而大大降低了节点背离协作的可能性。仿真结果表明,对节点的自私行为实施惩戒机制,可以大大增强节点间相互协作,从而保证网络的连通性。     

Best neighbor strategy to enforce cooperation among selfish nodes in wireless ad hoc network

Trust among nodes in a self-organizing network such as a mobile ad hoc network presents a number of problems and paradoxes. One of the challenging characteristics of wireless and mobile ad hoc networks consists in exploring ways to cope up with selfish behavior of neighbors towards network functions such as routing and forwarding. This paper attempts to deal with such mechanisms and as a result it introduces a distinct model to study the behavior of selfish neighbors using strategic, non-cooperative game theory. Many research works have used Tit-For-Tat strategy for analysis when they deploy game theory to stimulate cooperation. A compliant and an adaptable strategy called Best Neighbor Strategy [BNS] is proposed in this paper for the packet forwarding game in a wireless ad hoc environment. The behavior of nodes is probed varying the proportion of selfishness and also the size of the population while forwarding the packets. The investigations have brought out that the proposed cooperation enforcement policy is scalable, is able to converge faster and is robust against selfishness. BNS achieves evolutionary stability even under the invasion of selfish strategy at different proportions. Further, BNS proves to be a pure evolutionary stable strategy as it evolves to dominate the population from whatever the initial frequency it starts with and it totally out-competes the malign behavior shown by selfish strategy, which means that BNS is immune to invaders. The observations and analysis have shown that the ad hoc paradigm can be modeled significantly using an approach, which has been developed for game theory.     

基于演化博弈论的移动Ad Hoc网络中继协作机制

从演化博弈论的角度,提出一种能有效激励无线Ad Hoc网络节点参与数据分组中继协作的纳什均衡策略:G-TFT(Generous Tit for Tat).以节点中继的分组数与所需的能量开销为均衡点,建立了中继协作过程的单阶段博弈模型G,验证了节点的自私性动机,将G扩展为基于时闻序列、策略可转换的演化博弈R,并根据R的纳什均衡提出了协作激励策略G-TFT.仿真结果表明.通过调整宽容因子g,G-TFT能有效地激励节点参与中继协作.     

Mitigating transient loops through interface-specific forwarding

Under link-state routing protocols such as OSPF and IS–IS, when there is a change in the topology, propagation of link-state advertisements, path recomputation, and updating of forwarding tables (FIBs) will all incur some delay before traffic forwarding can resume on alternate paths. During this convergence period, routers may have inconsistent views of the network, resulting in transient forwarding loops. Previous remedies proposed to address this issue enforce a certain order among the nodes in which they update their FIBs. While such approaches succeed in avoiding transient loops, they incur additional message overhead and/or increased convergence delay. We explore an alternative approach, loopless interface-specific forwarding (LISF), that mitigates transient loops by forwarding a packet based on both its incoming interface and destination address. LISF needs to compute and update interface-specific instead of interface-independent forwarding tables. But it requires neither the synchronization of FIB updates at different nodes nor the modification of the existing link-state routing mechanisms. LISF is easily deployable with current routers if they already maintain a FIB at each interface for lookup efficiency. This paper presents the LISF approach, illustrates its strengths and limitations, discusses four alternative implementations of it and evaluates their performance.     

基于分布式信任管理的时延容忍网络数据转发方案

为解决时延容忍网络中恶意或自私节点严重影响网络性能的问题,提出一种基于分布式信任管理的时延容忍网络数据转发方案.通过计算节点信任值先滤除网络中的恶意节点,再执行数据转发行为.根据节点的转发行为以及它们的能量消耗信息计算出直接信任;邻居节点推荐的信息融合间接信任和推荐信誉计算出推荐信任;融合直接信任和推荐信任得到节点总体...     

一种面向机会网络路由的最优停止决策方法

投递延迟是机会网络的一个重要指标,给定节点缓存和消息副本数目限制,如何选择合适的节点复制消息成为一个关键问题.提出一种基于最优停止理论的路由决策方法（OSDR）.OSDR 将每个时隙上所遇节点和目标节点的平均相遇时间看做一个随机变量,根据该随机变量的统计特性得到一个停止观察、复制消息的规则,该规则呈现简单的阈值结构,即当某个时隙上所遇节点和目标节点的平均相遇时间小于给定阈值时即复制消息. OSDR 可以在较小的相遇间隔和等待成本之间进行折衷,实现数学期望意义上的最小消息投递延迟.介绍了OSDR 的网络模型、最优停止规则的存在性证明过程以及计算方法.模拟实验结果表明,OSDR 相对其他方法,在投递成功率、投递延迟等方面具有明显优势.     

Utility-aware data transmission scheme for delay tolerant networks

Social-based routing approaches in delay-tolerant networks have attracted widespread attention in recent years, which attempt to import social behaviors and relations in real scene for node mobility. However, most social-based schemes resort to users’ contact history and social relations that are dynamic, causing it so hard to establish stable relations between nodes. In this paper, we propose a utility-aware data transmission scheme which considers both internal property and external contact of nodes. Inspired by the concept of transfer station in real life, we set a central group and choose nodes for message forwarding, which have higher utility, i.e., enough energy, adequate cache, and more nodes encountered during the motivation. Two extensions are proposed also to further reduce the overhead. Simulation results demonstrate the increase in delivery ratio and decrease in overhead ratio, especially in large scale scenarios.     

节点度估计和静态博弈转发策略的Ad Hoc网络路由协议

针对Ad Hoc网络路由发现过程中广播路由请求分组导致的广播风暴问题，提出了一种基于节点度估计和静态博弈转发策略的Ad Hoc网络路由协议NGRP.NGRP考虑边界影响，采用分段函数的思想将网络场景分为中心、边和角区域，分别估算网络中节点在不同区域的节点度，避免了周期性广播Hello消息获取节点度导致的开销；NGRP路由请求分组的转发采用静态博弈转发策略，利用节点度估算参与转发路由请求分组的节点数量，将转发和不转发作为策略集合，设计效益函数，通过纳什均衡获得节点转发路由请求分组的转发概率，从而减少了路由请求分组广播过程中产生的大量的冗余、竞争和冲突，提高了路由发现过程中路由请求分组的广播效率.运用NS-2对协议的性能进行大量的仿真，结果表明：NGRP的分组投递率、路由开销、MAC层路由开销和吞吐率这4项指标明显优于AODV+FDG，AODV with Hello和AODV without Hello协议.     

节点移动状态感知的社会化延迟容忍网络路由策略

针对延迟容忍网络因节点移动的时空特性变化导致网络性能下降的问题,建立半马尔可夫模型描述节点的移动过程,预测未来时刻节点处于某一地理区域的概率和节点间在未来时间段内的连接状态;同时,采用节点移动状态感知机制,对所预测结果的准确程度进行评估,进而提出了节点移动状态变化自适应的消息转发策略。仿真结果表明,基于节点移动状态感知的路由策略在网络交付率、开销比率及消息投递平均延时方面能够提升DTN的性能。     

Ad hoc网络寻路阶段的合作激励机制研究

如何激励属于不同利益最大化实体的自私节点合作是当前Adhoc网络研究中的一个热点问题.现有的自私节点检测和激励机制主要针对数据传输阶段,不能适应寻路阶段的特点.文中基于邻居节点中继和生成的路由请求包之间的统计关系,提出了一种适用于按需路由协议寻路阶段的自私行为检测和惩罚机制,并利用博弈论工具将其建模为噪声环境下的重复囚徒困境博弈,对算法激励合作的有效性进行分析.理论分析和仿真结果显示,该算法能够有效地惩罚寻路中的自私行为,促进节点合作.     

CAF: Community aware framework for large scale mobile opportunistic networks

The fundamental challenge in opportunistic networking is when and how to forward a message. Rank-based forwarding, one of the most promising methods for addressing this challenge, ranks nodes based on their social profiles or contact history in order to identify the most suitable forwarders. While these forwarding techniques have demonstrated great performance trends, we observe that they fail to efficiently forward messages in large scale networks. In this paper, we demonstrate using real mobility traces, the weakness of existing rank-based forwarding algorithms in large scale communities. We propose strategies for partitioning large communities into sub-communities based on geographic locality or social interests. We also propose exploiting particular nodes, named MultiHomed nodes, in order to disseminate messages across these sub-communities. We introduce CAF, a Community Aware Forwarding framework, which is designed to be integrated with state-of-the-art rank-based forwarding algorithms, in order to improve their performance in large scale networks. We use real mobility traces to evaluate our proposed techniques. Our results empirically show a delivery success rate increase of up to 40%, along with 5% to 30% improved success delivery rates compared to state-of-the-art rank-based forwarding algorithms; these results are obtained while incurring a marginal increase in cost which is less than 10%. We finally propose an extension of the original framework called Community Destination Aware Framework (CDAF). Assuming that the source node can determine the destination’s community, CDAF further reduces the cost of CAF by a factor of 2 while maintaining similar success rates.     

机会网络中基于移动特征的效用转发协议*

针对非社区网络中的主流转发协议未考虑到节点移动的非完全随机性,提出一种基于移动特征的效用转发协议。每个节点关联两个移动特征——活跃度和相似度,依靠活跃节点带动消息的适当发散和递交,并通过相似度的判定和效用值的比较降低网络开销。仿真结果表明,该协议在保持相对平稳的端到端延时的情况下,可以提高消息递交率,降低网络资源消耗。     

A secure routing scheme based on social network analysis in wireless mesh networks无线网状网中一种基于社会网络分析的安全路由机制

As an extension of wireless ad hoc and sensor networks, wireless mesh networks (WMNs) are employed as an emerging key solution for wireless broadband connectivity improvement. Due to the lack of physical security guarantees, WMNs are susceptible to various kinds of attack. In this paper, we focus on node social selfish attack, which decreases network performance significantly. Since this type of attack is not obvious to detect, we propose a security routing scheme based on social network and reputation evaluation to solve this attack issue. First, we present a dynamic reputation model to evaluate a node’s routing behavior, from which we can identify selfish attacks and selfish nodes. Furthermore, a social characteristic evaluation model is studied to evaluate the social relationship among nodes. Groups are built based on the similarity of node social status and we can get a secure routing based on these social groups of nodes. In addition, in our scheme, nodes are encouraged to enter into multiple groups and friend nodes are recommended to join into groups to reduce the possibility of isolated nodes. Simulation results demonstrate that our scheme is able to reflect node security status, and routings are chosen and adjusted according to security status timely and accurately so that the safety and reliability of routing are improved.     

移动社会网络中基于活动的消息机会转发

针对移动社会网络中节点移动形成的成簇特性和节点参与活动表现的周期特点,提出了一种基于活动的消息机会转发算法（activity-based message opportunistic forwarding,简称AMOF）.算法思想是：当消息携带节点与目的节点存在相同活动时,选择消息交付概率高的中继节点转发消息;当消息携带节点与目的节点不存在相同活动时,选择消息间接交付概率高的链路来转发消息.仿真结果表明,与经典路由算法（如Epidemic,PRoPHET,CMOT和CMTS）比较,所提出的路由算法不仅能够提高消息的传输成功率,还能有效地降低传输时延和网络负载.     

基于博弈论的能量均衡路由算法

针对传感器网络能量不均衡且网络性能易受自私节点影响的问题,利用博弈论的思想,构建了均衡能耗的博弈模型(EBGM)。该算法从激励节点合作行为出发,引入能量关注因子,摒除传统博弈算法以剩余能量作为调整转发意愿的唯一标准,转而根据节点现有能量比例与邻居能量比例的差异程度进行调节。对EBGM模型进行理论分析,证明了纳什均衡点的存在性,且其能够趋于帕累托最优。仿真结果表明,EBGM模型能够促进节点合作行为、均衡能量开销、延长网络的整体生存周期。     

一种面向延迟容忍网络的信誉方案

延迟容忍网络(DTN)的节点资源受限,易产生自私行为影响网络性能。针对该问题,提出一种面向DTN的信誉方案,以减小自私行为对网络性能的影响。设计报文转发协议和行为记录机制,检测DTN环境下的自私行为,建立信誉模型,实现对网络节点可信度的评估。实验结果表明,该方案可在存有自私节点的环境中提高网络性能。     

一种新的效用冗余混合DTN路由算法

针对容迟网络(DTN)的高延迟、间歇性连接和资源受限等特点,提出一种新的效用冗余混合DTN路由算法NHRA。根据节点的相遇频率和连通时长等信息估算消息转发效用,指定消息在网络中的最大拷贝数,根据消息转发效用结合基于二叉树的方法来分配消息拷贝任务,实现消息的多路径并行传输,在提高传输性能的同时,有效地控制了网络开销。仿真实验结果表明,与现有相关算法相比,该算法可获得更高的消息传达率,并且花费的通信开销更低。