传感器网络中对偶密钥建立协议研究

传感器节点部署的随机性可能导致网络中出现孤立的密钥共享连通集团。为解决这一问题,提出了基于信任关系传递的多点信任模型,构造了基于信任域认证的对偶密钥建立协议。仿真结果表明：该协议具有良好的抗妥协性能,能够有效地实现孤立集团间的互联,从而验证了其安全性和有效性。     

A hierarchical architecture for detecting selfish behaviour in community wireless mesh networks

Wireless mesh networks (WMNs) consist of dedicated nodes called mesh routers which relay the traffic generated by mesh clients over multi-hop paths. In a community WMN, all mesh routers may not be managed by an Internet Service Provider (ISP). Limited capacity of wireless channels and lack of a single trusted authority in such networks can motivate mesh routers to behave selfishly by dropping relay traffic in order to provide a higher throughput to their own users. Existing solutions for stimulating cooperation in multi-hop networks use promiscuous monitoring or exchange probe packets to detect selfish nodes and apply virtual currency mechanism to compensate the cooperating nodes. These schemes fail to operate well when applied to WMNs which have a multi-radio environment with a relatively static topology. In this paper we, propose architecture for a community WMN which can detect selfish behaviour in the network and enforce cooperation among mesh routers. The architecture adopts a decentralized detection scheme by dividing the mesh routers into manageable clusters. Monitoring agents hosted on managed mesh routers monitor the behaviour of mesh routers in their cluster by collecting periodic reports and sending them to the sink agents hosted at the mesh gateways. To make the detection more accurate we consider the quality of wireless links. We present experimental results that evaluate the performance of our scheme.     

An interference-aware fair scheduling for multicast in wireless mesh networks

Multicast is a fundamental routing service in wireless mesh networks (WMNs) due to its many potential applications such as video conferencing, online games, and webcast. Recently, researchers proposed using link-quality-based routing metrics for finding high-throughput paths for multicast routing. However, the performance of such link-quality-based multicast routing is still limited by severe unfairness. Two major artifacts that exist in WMNs are fading which leads to low quality links, and interference which leads to unfair channel allocation in the 802.11 MAC protocol. These artifacts cause the multicast application to behave unfairly with respect to the performance achieved by the multicast receivers.     

Load-balanced mesh router migration for wireless mesh networks

Load-balancing among domains in a wireless mesh network (WMN) is normally achieved by changing the Internet attachment of mesh routers (MRs) that carry the traffic from mobile stations (MSs). The greediness of load-balancing algorithms may force MRs to frequently change their Internet attachments, and thus degrade network performance due to inter-domain mobility of the associated MSs. In this paper, we discuss the negative impact on the performance of MSs’ mobility, due to inter-domain reassignment of MR. A MR migration scheme is proposed to achieve a tradeoff between load-balancing and inter-domain reassignment of MR. The proposed load-balancing scheme for WMNs includes: an initialization procedure to divide a WMN into domains, and a load adjustment procedure to rebalance the traffic load among the neighboring domains when required. We also provide a framework for handling inter-domain mobility in support of multi-hop communication using the Multi-hop cellular IP. Our simulation results show that the proposed protocol effectively controls MR’s change in connectivity as well as MS’s mobility.     

Routing protocols in wireless mesh networks: challenges and design considerations

Wireless Mesh Networks (WMNs) are an emerging technology that could revolutionize the way wireless network access is provided. The interconnection of access points using wireless links exhibits great potential in addressing the “last mile” connectivity issue. To realize this vision, it is imperative to provide efficient resource management. Resource management encompasses a number of different issues, including routing. Although a profusion of routing mechanisms has been proposed for other wireless networks, the unique characteristics of WMNs (e.g., wireless backbone) suggest that WMNs demand a specific solution. To have a clear and precise focus on future research in WMN routing, the characteristics of WMNs that have a strong impact on routing must be identified. Then a set of criteria is defined against which the existing routing protocols from ad hoc, sensor, and WMNs can be evaluated and performance metrics identified. This will serve as the basis for deriving the key design features for routing in wireless mesh networks. Thus, this paper will help to guide and refocus future works in this area.

A quality based routing protocol for wireless mesh networks

Wireless mesh networks can provide low-cost solutions for extending the reach of wireless access points by using multi-hop routing over a set of stationary wireless routers. The routing protocol for these networks may need to address quality considerations to meet the requirements of the user. In this paper, we present a quality based routing protocol for wireless mesh networks that tries to maximize the probability of successful transmissions while minimizing the end-to-end delay. The proposed routing protocol uses reactive route discoveries to collect key parameters from candidate routes to estimate the probability of success and delay of data packets transmitted over them. To achieve accurate route quality assessments, a new route quality metric is proposed that uses performance models of data packet transmissions as opposed to estimating route quality from the transmission of control packets, which have different transmission characteristics. These models are developed after careful evaluations of multi-hop wireless transmissions and validated by computer simulations. Relevant parameters that can be used to assess the route quality metric using these models are explained. Extensive performance evaluations of the proposed quality based routing protocol are presented and its benefits in comparison to some other known routing protocols are discussed.     

Approximate dynamic programming for link scheduling in wireless mesh networks

In this paper a novel interference-based formulation and solution methodology for the problem of link scheduling in wireless mesh networks is proposed. Traditionally, this problem has been formulated as a deterministic integer program, which has been shown to be -hard. The proposed formulation is based on dynamic programming and allows greater flexibility since dynamic and stochastic components of the problem can be embedded into the optimization framework. By temporal decomposition we reduce the size of the integer program and using approximate dynamic programming (ADP) methods we tackle the curse of dimensionality. The numerical results reveal that the proposed algorithm outperforms well-known heuristics under different network topologies. Finally, the proposed ADP methodology can be used not only as an upper bound but also as a generic framework where different heuristics can be integrated.     

Channel allocation in multi-channel wireless mesh networks

In this article, we survey the latest progress in multi-channel wireless mesh networks, focusing on wireless interference models and channel allocation algorithms with the goal of maximizing the network performance. We present the studies of different interference models and illustrate how they could affect the design of channel assignment. We also summarize channel allocation algorithms with different strategies in both omni-directional and directional antenna networks. We conclude that both static and dynamic channel allocation strategies have advantages and disadvantages, and the design of channel allocation algorithms strongly depends on the interference model and the assumption of network traffic.     

REUSE: A combined routing and link scheduling mechanism for wireless mesh networks

Increasing the capacity of wireless mesh networks has motivated numerous studies. In this context, the cross-layer optimization techniques involving joint use of routing and link scheduling are able to provide better capacity improvements. Most works in the literature propose linear programming models to combine both mechanisms. However, this approach has high computational complexity and cannot be extended to large-scale networks. Alternatively, algorithmic solutions are less complex and can obtain capacity values close to the optimal. Thus, we propose the REUSE algorithm, which combines routing and link scheduling and aims to increase throughput capacity in wireless mesh networks. Through simulations, the performance of the proposal is compared to a developed linear programming model, which provides optimal results, and to other proposed mechanisms in the literature that also deal with the problem algorithmically. We observed higher values of capacity in favor of our proposal when compared to the benchmark algorithms.     

WMN中基于轻量级CA的双向认证和密钥协商协议

针对无线Mesh网节点间认证过程复杂,效率低的问题,提出一种新的无线Mesh网双向认证和密钥协商协议。该协议使用椭圆曲线密码算法并结合轻量级CA公钥认证机制,降低了认证过程中的计算和通信开销。采用BAN逻辑对该协议进行形式化有效性验证,并对其安全性和性能进行分析,结果表明该协议具有较高的安全性和较高的通信效率。     

On the nominal capacity of multi-radio multi-channel wireless mesh networks

Wireless mesh networking is an emerging technology with a wide range of applications, from community to metropolitan area networking. Mesh networks consist of wireless routers and access points that make up the network backbone which is connected to the wired infrastructure. Client devices are located at the edge. The capacity of a wireless mesh network is an important performance indicator as well as design parameter. It depends on various factors such as network size and topology, expected traffic patterns, number of interfaces per node, number of channels, routing and channel assignment etc. In this paper, we present an analytical framework for estimating the capacity of wireless mesh networks, based on the concept of collision domains. The capacity of grid-oriented mesh networks is investigated for various scenarios to study the impact of different network parameters.     

基于部署信息的无线传感器网络配对密钥方案

在充分考虑无线传感器网络自身特点的基础上,针对现有无线传感器网络密钥管理中存在的问题,利用Blom矩阵,提出了一个基于部署信息的无线传感器网络密钥管理方案(KPSBM),并从该方案的安全性、连通性、可扩展性、有效性等方面进行分析,并与现有的一些常用方案进行了分析比较,结果表明,KPSBM在这些方面有较好的性能。     

Route Maintenance in IEEE 802.11 wireless mesh networks

In this paper, we propose a novel Route Maintenance scheme for IEEE 802.11 wireless mesh networks. Despite lack of mobility and energy constraints, reactive routing protocols such as AODV and DSR suffer from frequent route breakages in 802.11 based infrastructure wireless mesh networks. In these networks, if any intermediate node fails to successfully transmit a packet to the next hop node after a certain number of retransmissions, the link layer reports a transmission problem to the network layer. Reactive routing protocols systematically consider this as a link breakage (and therefore a route breakage). Transmission failures can be caused by a number of factors e.g. interference or noise and can be transient in nature. Frequent route breakages result in significant performance degradation. The proposed mechanism considers multiple factors to differentiate between links with transient transmission problems from those links which have permanent transmission problems and takes a coherent decision on link breakage. The proposed mechanism is implemented in AODV for single-radio single-channel mesh network and an extension is incorporated in multi-radio multi-channel scenarios. Simulation results show substantial performance improvement compared to classical AODV and local route repair schemes.     

On the credit evolution of credit-based incentive protocols in wireless mesh networks

In designing wireless mesh networks (WMNs), incentive mechanisms are often needed so to encourage nodes to relay or forward packets for other nodes. However, there is a lack of fundamental understanding on the interactions between the incentive mechanisms and the underlying protocols (e.g., shortest-path routing, ETX routing or back-pressure scheduling), and whether integration of these protocols will lead to a robust network, i.e., networks can sustain a given traffic workload. The objective of this paper is to present a general mathematical framework via stochastic difference equations to model the interaction of incentive mechanisms and various underlying protocols. We first present a credit evolution model to quantify the expected credit variation of each node in WMN, then use the norm of the expected credits variation to quantify the credit disparity. We also propose the use of differentiated pricing and show how it can achieve credit equality among nodes, resulting in a more robust network under different traffic loading. Our analytical framework can help researchers to model other incentive/routing protocols so to analyze the robustness of the underlying networks.     

基于遗传算法的无线网状网QoS多播路由算法

探讨了基于遗传算法的无线网状网QoS多播路由算法,选用边集表示方式对多播树进行编码,其空间复杂度为O(N),给出了该编码方式下的初始种群生成算法RandWalkMT,同时对传统的遗传操作进行改进使子代个体中不会产生非法多播树,从而避免了复杂的惩罚机制或多播树修复算法。实验表明该算法收敛快且性能较好。     

Zero-Degree algorithm for Internet GateWay placement in backbone wireless mesh networks

Internet GateWays (IGWs) are responsible for connecting the backbone wireless mesh networks (BWMNs) to the Internet/wired backbone. An IGW has more capabilities than a simple wireless mesh router (WMR) but is more expensive. Strategically placing the IGWs in a BWMN is critical to the Wireless Mesh Network (WMN) architecture. In order to solve the problem of IGWs placement in BWMNs, a novel algorithm is proposed in this paper. The new algorithm is involved in placing a minimum number of IGWs so that the Quality of Service (QoS) requirements are satisfied. Different from existing algorithms, this new algorithm incrementally identifies IGWs and prioritively assigns wireless mesh routers (WMRs) based on the computed degree of WMRs to identified IGWs. Performance evaluation results show that proposed algorithm outperforms other alternative algorithms by comparing the number of gateways placed in different scenarios. Furthermore, having control of the distribution of IGWs in order to locate them closest to available Internet/wired network connection points is an added advantage of this algorithm.     

Hierarchical agent-based secure and reliable multicast in wireless mesh networks

We propose and analyze a hierarchical agent-based secure and reliable multicast (HASRM) algorithm for efficiently supporting secure and reliable mobile multicast in wireless mesh networks, with design considerations given to minimize the overall network cost incurred by reliable multicast packet delivery, mobility management, security key management, and group membership maintenance. HASRM dynamically maintains a group of multicast agents running on mesh routers for integrated mobility and multicast service management and leverages a hierarchical multicast structure for secure and reliable multicast data delivery. The regional service size of each multicast agent is a key design parameter. We show via model-based performance analysis and simulation validation that there exists an optimal regional service size that minimizes the overall communication cost and the optimal regional service size can be dynamically determined. We demonstrate that HASRM under optimal settings significantly outperforms traditional algorithms based on shortest-path multicast trees extended with user mobility, security, and reliability support. We also show that a variant of HASRM is superior to a recently proposed multicast algorithm for secure group communication in wireless mesh networks.     

A CDMA/TDD approach for wireless mesh networks

Wide band mesh or star oriented networks have recently become a subject of greater interest. Providing wideband multimedia access for a variety of applications has led to the inception of mesh networks. Classic access techniques such as FDMA and TDMA have been the norm for such networks. CDMA maximum transmitter power is much less than TDMA and FDMA counter parts, which is an important asset for mobile operation. In this paper we introduce a code division multiple access/time division duplex technique CDMA/TDD for such networks. The CDMA approach is an almost play and plug technology for wireless access, making it amenable for implementation by the mesh network service station, SS. Further it inherently allows mesh network service stations to use a combination of turbo coding and dynamic parallel orthogonal transmission to improve network efficiency. We outline briefly the new transmitter and receiver structures then evaluate the efficiency, delay and delay jitter. By analysis we show the advantages over classic counter parts with respect to the total network efficiency achievable especially for larger number of hops.