无线网格网的跨层安全架构研究

概要介绍了无线网格网(WMN:wireless mesh networks)的发展状况、网络结构及主要优缺点,指出其是构建大规模无线宽带接入网络的一种经济、可行的理想方案;探讨了其安全服务的需求,在重点分析当前链路层和网络层安全协议的基础上,提出基于多信任域的跨层安全架构,来确保无线网格网中灵活高效的安全无线通信。     

Stochastic Traffic Engineering in Multihop Cognitive Wireless Mesh Networks

In this work, the stochastic traffic engineering problem in multihop cognitive wireless mesh networks is addressed. The challenges induced by the random behaviors of the primary users are investigated in a stochastic network utility maximization framework. For the convex stochastic traffic engineering problem, we propose a fully distributed algorithmic solution which provably converges to the global optimum with probability one. We next extend our framework to the cognitive wireless mesh networks with nonconvex utility functions, where a decentralized algorithmic solution, based on learning automata techniques, is proposed. We show that the decentralized solution converges to the global optimum solution asymptotically.     

Cross-Layer Optimized Video Streaming Over Wireless Multihop Mesh Networks

The proliferation of wireless multihop communication infrastructures in office or residential environments depends on their ability to support a variety of emerging applications requiring real-time video transmission between stations located across the network. We propose an integrated cross-layer optimization algorithm aimed at maximizing the decoded video quality of delay-constrained streaming in a multihop wireless mesh network that supports quality-of-service. The key principle of our algorithm lays in the synergistic optimization of different control parameters at each node of the multihop network, across the protocol layers-application, network, medium access control, and physical layers, as well as end-to-end, across the various nodes. To drive this optimization, we assume an overlay network infrastructure, which is able to convey information on the conditions of each link. Various scenarios that perform the integrated optimization using different levels ("horizons") of information about the network status are examined. The differences between several optimization scenarios in terms of decoded video quality and required streaming complexity are quantified. Our results demonstrate the merits and the need for cross-layer optimization in order to provide an efficient solution for real-time video transmission using existing protocols and infrastructures. In addition, they provide important insights for future protocol and system design targeted at enhanced video streaming support across wireless mesh networks     

A Cross-Layer Optimization Framework for Multihop Multicast in Wireless Mesh Networks

The optimal and distributed provisioning of high throughput in mesh networks is known as a fundamental but hard problem. The situation is exacerbated in a wireless setting due to the interference among local wireless transmissions. In this paper, we propose a cross-layer optimization framework for throughput maximization in wireless mesh networks, in which the data routing problem and the wireless medium contention problem are jointly optimized for multihop multicast. We show that the throughput maximization problem can be decomposed into two subproblems: a data routing subproblem at the network layer, and a power control subproblem at the physical layer with a set of Lagrangian dual variables coordinating interlayer coupling. Various effective solutions are discussed for each subproblem. We emphasize the network coding technique for multicast routing and a game theoretic method for interference management, for which efficient and distributed solutions are derived and illustrated. Finally, we show that the proposed framework can be extended to take into account physical-layer wireless multicast in mesh networks     

一种多跳无线网扩频码分配算法

在多跳分组无线网中使用码分多址(CDMA)技术可以明显地降低隐终端问题对网络造成的影响.码分配是多跳无线网中使用CDMA的基本问题.码分配的目的在于提高扩频码的空间重用、降低分组冲突以及反映网络的动态变化.本文提出了一种多跳无线网扩频码分配算法,证明了其正确性并与其它算法比较了复杂度.与以往的算法追求降低码的数目不同,本算法是假设扩频码的数目有一定的冗余,寻求算法的方便、快捷和低通信开销.     

无线网状网络路由安全协议综述

无线网状网络(Wireless Mesh Networks,WMN)是近年来得到长足发展的一项新兴技术。它是一种分布式的无线网络,并将Ad hoc以及WLAN的优势结合起来,因此具有很广阔的应用前景。然而,目前的WMN技术还不够成熟,存在诸多安全问题,如何完善网络中的安全机制就成了目前研究的重点之一。本文从介绍WMN的基本结构开始,逐步介绍其安全性所面临的问题,以及各种安全的路由协议,最后对一些路由安全协议进行对比分析。     

无线Ad hoc网络的安全体系

在敌对环境下,Ad hoc网络易受攻击,尤其来自网络内部的攻击更具威胁性。针对这种情况,本文介绍了一种无线Ad hoc网络安全体系模型,并着重介绍了利用不完全信任管理机制来防止网络内部的攻击。     

无线Mesh网络安全研究

无线Mesh网络（Wireless Mesh Networks,WMN）是下一代网络中的新型技术,和传统网络不同,它可以不依赖任何固定的设施,主机可以相互依赖保持网络连接。WISP可以利用它提供快速、简单、低廉的网络部署,然而存在一个主要的挑战就是易于遭受攻击。文中介绍了无线Mesh网络的体系机构以及特点,分析并研究其存在的安全性威胁以及现有的关键安全解决机制。     

Energy-Efficient SINR-Based Routing for Multihop Wireless Networks

In this paper, we develop an energy-efficient routing scheme that takes into account the interference created by existing flows in the network. The routing scheme chooses a route such that the network expends the minimum energy satisfying with the minimum constraints of flows. Unlike previous works, we explicitly study the impact of routing a new flow on the energy consumption of the network. Under certain assumptions on how links are scheduled, we can show that our proposed algorithm is asymptotically (in time) optimal in terms of minimizing the average energy consumption. We also develop a distributed version of the algorithm. Our algorithm automatically detours around a congested area in the network, which helps mitigate network congestion and improve overall network performance. Using simulations, we show that the routes chosen by our algorithm (centralized and distributed) are more energy efficient than the state of the art.     

A Distributed and Collaborative Intrusion Detection Architecture for Wireless Mesh Networks

Wireless Mesh Network (WMN) is an emerging heterogeneous network architecture that is growing in importance among traditional wireless communication systems as a cost-effective way of providing Internet services. However, WMNs are particularly vulnerable to malicious nodes given their inherent attributes such as decentralized infrastructure and high dependence of node cooperation. We then propose a distributed and Collaborative Intrusion Detection System (CIDS) architecture for detecting insider attacks at real-time, which comprises: i) a Routing Protocol Analyzer (RPA) to analyze the collected routing traffic and generate respective Routing Events; ii) a Distributed Intrusion Detection Engine (DIDE) that treats the Routing Events by applying Routing Constraints and calculate related Misbehaving Metrics; iii) a Cooperative Consensus Mechanism (CCM) to check the Misbehaving Metrics using a proposed threshold scheme and to track down the source of intrusion. The entire CIDS solution is implemented in a virtualized mesh network platform. The experimental results show the proposed CIDS architecture efficiently detects message fabrication attacks with good precision and low resource consumption.     

无线Mesh网络跨层优化及其安全机制研究

新兴的无线Mesh网络作为无线宽带接入网具有巨大的应用价值。基于最新无线通信技术标准,结合无线Mesh网络的特点,以网络性能及资源最大化利用为优化目标,提出对无线Mesh网络中物理层、媒体接入/数据链层、网络层各层间进行联合优化,并对无线Mesh网络相关的网络安全机制架构关键技术进行前瞻性的应用基础研究,为无线Mesh网络的组网与应用提供理论支持和技术保障。     

An Effective QoS Differentiation Scheme for Wireless Mesh Networks

Wireless mesh networking is emerging as an important architecture for future-generation wireless communications systems. Quality of service provisioning is a challenging issue in WMNs. In this article we study an effective QoS differentiation scheme for IEEE 802.16 WiMAX mesh networks. Both collocated and general topologies are exploited. Illustrative numerical examples are presented to demonstrate the effectiveness of the proposed strategy. The impact of key parameters on performance is discussed for differentiating various services. Moreover, with the proposed scheme, WMN scalability can be greatly improved. The challenges with respect to the integration of WMN and cooperative transmission are discussed, and the fairness problem is addressed with potential solutions.     

Efficient and Resilient Backbones for Multihop Wireless Networks

We consider the problem of finding "backbones" in wireless networks. The backbone provides end-to-end connectivity, allowing non-backbone nodes to save energy since they do not route or forward non-local data. Ideally, such a backbone would be small, consist primarily of high capacity nodes, and remain connected even when nodes move or fail. Unfortunately, it is often infeasible to construct a backbone that has all of these properties, e.g., a small optimal backbone is often too sparse to handle node failures or high mobility. We present a parameterized backbone construction algorithm that permits explicit tradeoffs between backbone size, resilience to node movement and failure, energy consumption, and path lengths. We prove that our scheme can construct essentially best possible backbones (with respect to energy consumption and backbone size) when the network is relatively static. We generalize our scheme to build more robust structures better suited to high-mobility scenarios. We present a distributed protocol based upon our algorithm and show that this protocol builds and maintains a connected backbone in dynamic networks. Finally, we present detailed packet-level simulations to evaluate and compare our scheme against existing energy-saving techniques. Depending on the network environment, our scheme increases network lifetimes by 20—220% without adversely affecting network performance.     

Cross-Layer Design for QoS Support in Multihop Wireless Networks

Due to such features as low cost, ease of deployment, increased coverage, and enhanced capacity, multihop wireless networks such as ad hoc networks, mesh networks, and sensor networks that form the network in a self-organized manner without relying on fixed infrastructure is touted as the new frontier of wireless networking. Providing efficient quality of service (QoS) support is essential for such networks, as they need to deliver real-time services like video, audio, and voice over IP besides the traditional data service. Various solutions have been proposed to provide soft QoS over multihop wireless networks from different layers in the network protocol stack. However, the layered concept was primarily created for wired networks, and multihop wireless networks oppose strict layered design because of their dynamic nature, infrastructureless architecture, and time-varying unstable links and topology. The concept of cross-layer design is based on architecture where different layers can exchange information in order to improve the overall network performance. Promising results achieved by cross-layer optimizations initiated significant research activity in this area. This paper aims to review the present study on the cross-layer paradigm for QoS support in multihop wireless networks. Several examples of evolutionary and revolutionary cross-layer approaches are presented in detail. Realizing the new trends for wireless networking, such as cooperative communication and networking, opportunistic transmission, real system performance evaluation, etc., several open issues related to cross-layer design for QoS support over multihop wireless networks are also discussed in the paper.     

WMN中一种基于干扰感知的负载均衡路由协议

无线信道干扰和负载分布的不均衡严重影响无线Mesh网络吞吐量、端到端延时和资源利用率。在已有基于信噪比和邻居节点个数的干扰模型基础上,进一步研究了无线Mesh网络的链路干扰。在综合考虑了无线Mesh网络流间干扰和和流内干扰的基础上,提出路由判据PIL（Path Interfer-ence Level）。在此基础上,提出一种新的基于干扰感知的负载均衡路由协议IA-DSR（Interference-Aware DSR）。IA-DSR考虑无线网络拥塞并选择受到干扰最小的路径。仿真结果表明,在不显著增加开销的情况下,IA-DSR可以有效地提高网络的整体吞吐量,降低网络端到端时延和丢包率。     

Scalability Technologies for Wireless Mesh Networks

The continuous increase of data transmission density in wireless mobile communications has posed a challenge to the system performance of Wireless Mesh Networks (WMNs ). There is a rule for wireless Ad hoc networks that the average node capacity decreases while the number of nodes increases , so it is hard to establish a large - scale wireless Mesh network. Network scalability is very important for enhancing the adaptive networking capability of the wireless Mesh network. This article discusses key scalability technologies for Mesh Base Stations (BSs ) and Mesh Mobile Stations (MSs ), such as channel allocation, intelligent routing , multi- antenna , node classification, Quality of Service (QoS) differentiation and cooperative transmission.     

A Smart TCP Acknowledgment Approach for Multihop Wireless Networks

Reliable data transfer is one of the most difficult tasks to be accomplished in multihop wireless networks. Traditional transport protocols like TCP face severe performance degradation over multihop networks given the noisy nature of wireless media as well as unstable connectivity conditions in place. The success of TCP in wired networks motivates its extension to wireless networks. A crucial challenge faced by TCP over these networks is how to operate smoothly with the 802.11 wireless MAC protocol which also implements a retransmission mechanism at link level in addition to short RTS/CTS control frames for avoiding collisions. These features render TCP acknowledgments (ACK) transmission quite costly. Data and ACK packets cause similar medium access overheads despite the much smaller size of the ACKs. In this paper, we further evaluate our dynamic adaptive strategy for reducing ACK-induced overhead and consequent collisions. Our approach resembles the sender side's congestion control. The receiver is self-adaptive by delaying more ACKs under nonconstrained channels and less otherwise. This improves not only throughput but also power consumption. Simulation evaluations exhibit significant improvement in several scenarios     

Profit-Based Routing for Multihop Coverage Extension in Wireless Networks

In future wireless systems, the coverage of a base station will decrease due to the characteristics of the channel at high-frequency bands. To expand the service coverage, a hybrid network that combines an ad hoc network with a cellular (or wireless LAN) network, appears to have great potential. In such systems, some mobile users outside the service area can access the network with the aid of other intermediate mobiles. However, this method incurs energy consumption in routing users, which could be a serious obstacle for wide-spread deployment of multihop wireless networks. Therefore we consider a revenue-cost model and propose a profit-based routing strategy that encourages routing users to actively participate in the relaying service because they are compensated for their energy consumption cost. Our strategy enables each mobile node to find an appropriate multihop path to a base station (or access point) that satisfies the interests of the service provider and the users. Numerical results show that our model successfully expands the network coverage area while ensuring the profit of each system involved.     

Time-Driven Access and Forwarding for Industrial Wireless Multihop Networks

The deployment of wireless technologies in industrial networks is very promising mainly due to their inherent flexibility. However, current wireless solutions lack the capability to provide the deterministic, low delay service required by many industrial applications. Moreover, the high level of interference generated by industrial equipment limits the coverage that ensures acceptable performance. Multihop solutions, when combining frame forwarding with higher node density, have the potential to provide the needed coverage while keeping radio communication range short. However, in multihop solutions, the medium access time at each of the nodes traversed additively contributes to the end-to-end delay and the forwarding delay (i.e., the time required for packets to be processed, switched, and queued) at each node is to be added as well. This paper describes time-driven access and forwarding, a solution for guaranteeing deterministic delay, at both the access and forwarding level, in wireless multihop networks, analyzes its properties, and assesses its performance in industrial scenarios.