A Hybrid Centralized Routing Protocol for 802.11s WMNs

Wireless mesh networks (WMNs) are being widely accepted as a critical wireless access solution for various applications. Due to minimal mobility in mesh nodes, a backbone topology can be effectively maintained in WMN using a proactive routing protocol. In IEEE 802.11s standard, a tree-based routing (TBR) protocol is adopted as a viable proactive routing protocol for a WMN with user traffic flowing to/from a wired network through a root (i.e., a mesh portal). However, the performance of the TBR protocol degrades rapidly as the user traffic becomes dominated by intra-mesh traffic. The reason is that the routing path through the root even for intra-mesh traffic unnecessarily overloads the root. Furthermore, the TBR performance becomes more severe when the network size of WMN is large, which could lead to the huge amount of intra-mesh traffic towards the root. To overcome these problems, we propose a new routing mechanism, root driven routing (RDR) protocol, for the root to quickly determine the best-metric route for any source-destination pair of intra-mesh traffic. For inter-mesh traffic, the original TBR protocol is employed. Thus, the hybrid centralized routing protocol that combines TBR and RDR and is adaptive to all traffic scenarios. Our simulation results reveal that the proposed RDR protocol outperforms the TBR protocol with much lower average end-to-end delay and much higher packet delivery ratio for intra-mesh traffic. The simulation results also provide some insight into the right tradeoff between the TBR protocol and the RDR protocol to achieve the best performance of the hybrid centralized routing protocol for WMNs.     

WMN多路径路由算法安全性分析与仿真

高效、安全的路由机制是保证无线网状网络(WMN)正常工作的一个重要因素。对WMN中的多径路由(MPR)算法进行了研究。由于MPR算法存在路由分离性约束,提出了一种基于转移概率的随机路由(SR)算法,并对这两种算法进行了仿真。仿真结果表明:在节点转发次数的标准方差和最高截获率两个性能指标方面,SR算法均优于MPR算法,这说明与MPR算法相比,所提算法进一步增强了WMN网络的路由安全性。     

光无线混合宽带接入网的路由技术研究

文章研究了光无线混合宽带接入网(HOW BAN)后端无源光网络(PON)采用的多点控制协议以及前端无线网状网(WMN)中的各种路由机制,重点研究了几种适用于HOW BAN前端WMN的路由算法:最小跳路由算法、最短路径路由算法、风险和时延感知的路由算法、感知时延路由算法、预测吞吐量路由算法、容量和时延感知的路由算法、能量感知的路由算法、流量限制路由算法、时延区分路由算法。对HOW BAN中的传输协议,文章指出保持服务公平性、保证健壮性、提高服务质量(QoS)、节约能源、保障安全性、适应多频道网络等问题值得深入研究。     

Predictability of Aggregated Traffic of Gateways in Wireless Mesh Network with AODV and DSDV Routing Protocols and RWP Mobility Model

When evaluating the performance of routing protocols in wireless mesh network (WMN), we need deeper analysis from the aspect of network traffic complexity to show how traffic characteristics are influenced by routing protocols and node mobility. The predictability of network traffic can be used as one metric of complexity and can be analyzed by multi-scale entropy (MSE) method. With 20 different random waypoint (RWP) mobility scenarios and with destination sequenced distance vector (DSDV), a typical proactive protocol, and Ad hoc on-demand distance vector (AODV), a typical reactive protocol, the predictabilities of aggregated traffic of gateway in WMN are analyzed using MSE method to show how different routing protocols bear different mobility scenarios. The MSE results show that the aggregated traffic of gateway with DSDV is more difficult to be predicted than that with AODV for different mobility scenarios. The maxspeed parameter of RWP dominates the traffic predictability for AODV. Both of the pause time and the maxspeed parameters, have great influence on the traffic predictability for DSDV. The reasons lie in the behaviors of routing protocols, i.e., AODV has up-to-date paths while DSDV does not.     

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。     

Design and Performance Study for a Mobility Management Mechanism (WMM) Using Location Cache for Wireless Mesh Networks

Wireless mesh networks (WMNs) have emerged as one of the major technologies for 4G high-speed mobile networks. In a WMN, a mesh backhaul connects the WMN with the Internet, and mesh access points (MAPs) provide wireless network access service to mobile stations (MSs). The MAPs are stationary and connected through the wireless mesh links. Due to MS mobility in WMNs, mobility management (MM) is required to efficiently and correctly route the packets to MSs. We propose an MM mechanism named Wireless mesh Mobility Management (WMM). The WMM adopts the location cache approach, where mesh backhaul and MAPs (referred to as mesh nodes (MNs)) cache the MS's location information while routing the data for the MS. The MM is exercised when MNs route the packets. We implement the WMM and conduct an analytical model and simulation experiments to investigate the performance of WMM. We compare the signaling and routing cost between WMM and other existing MM protocols. Our study shows that WMM has light signaling overhead and low implementation cost.     

Interference and traffic aware channel assignment in WiFi-based wireless mesh networks

Wireless mesh networks (WMN) typically employ mesh routers that are equipped with multiple radio interfaces to improve network capacity. The key aspect is to cleverly assign different channels (i.e., frequency bands) to each radio interface to form a WMN with minimum interference. The channel assignment must obey the constraints that the number of different channels assigned to a mesh router is at most the number of interfaces on the router, and the resultant mesh network is connected. This problem is known to be NP-hard. In this paper we propose a hybrid, interference and traffic aware channel assignment (ITACA) scheme that achieves good multi-hop path performance between every node and the designated gateway nodes in a multi-radio WMN network. ITACA addresses the scalability issue by routing traffic over low-interference, high-capacity links and by assigning operating channels in such a way to reduce both intra-flow and inter-flow interference. The proposed solution has been evaluated by means of both simulations and by implementing it over a real-world WMN testbed. Results demonstrate the validity of the proposed approach with performance increase as high as 111%.     

Way-Point Multicast Routing Framework for improving QoS in hybrid wireless mesh networks

Since internet access is used by billions of people worldwide and the number of internet user is also increasing every day, a new technology called as wireless mesh network (WMN) is becoming popular. This is because it has some desirable characteristic, but it has some limitation for multi-hop routing, bandwidth, and many more. In order to overcome these issues, we proposed Way-Point Multicast Routing Framework (WPMRF) for improving the quality of service (QoS) in Hybrid WMN. Initially, the multicast framework is established based on the minimum load factor. The route established with least load factor is considered, as it avoids any kind of congestion in the network. After that, segmentation of route is done, and the way-point nodes are selected to join the multicast session. After that, the transmission is performed using MAODV and ODMRP protocol. In addition, an estimated route disconnection parameter is used for fast route recovery process and helps to select more reliable route path. The advantage of the proposed work is that it provides more reliable routing path to increase the quality of service (QoS) with fast route recovery process.     

无线Mesh网络路由协议研究

无线Mesh网络WMN（wireless mesh networks）是一种新型的无线网络,它融合了无线局域网（WLAN）和Ad Hoc网络的优势,成为宽带接入的一种有效手段。首先介绍了无线Mesh网的网络结构和特点．并在此基础上讨论了无线Mesh网络对路由协议的要求。无线Mesh网络的路由算法是Mesh领域的研究难点,通过分析比较4种针对WMN的路由协议,总结了现有的路由协议的优缺点,并对今后的研究方向做出了展望。     

WMN中基于免疫算法的QoS路由研究

无线Mesh网络的路由技术是影响网络性能的一个关键问题。针对无线Mesh网络的QoS多约束路由算法难于找到最优路径的问题,提出了一种基于免疫算法的路由算法,利用免疫算法的寻优能力,实现了无线Mesh网络QoS多约束条件下的最优路径选择,并与基于遗传算法的路由算法进行了比较。实验结果表明,利用免疫算法获得满足QoS要求的最佳路径时,不容易陷入局部最优,且收敛速度快,性能优越,更符合无线通信实时性的要求。     

基于WMN变节节点多径检测的Petri网模型分析

针对WMN中出现的安全问题,提出了利用WMN多径特性的密钥协商模型,可以在防止中间人攻击的同时发现网络中的变节节点。采用Petri网理论对模型结构特性及安全性进行形式化分析,对发现的漏洞给出解决方案。通过引入新的变节节点的检测安全模型和算法,使WMN的安全性得到增强。     

Hybrid QoS based routing protocol for inter and intra wireless mesh infrastructure communications

Quality of service (QoS) in wireless mesh networks is an active area of research, which is driven by the increasing demand for real-time and multimedia applications, such as Voice over IP and Video on Demand. In this paper, we propose a novel QoS based routing protocol for wireless mesh infrastructure, called Hybrid QoS Mesh Routing (HQMR). It is composed of two QoS based routing sub-protocols: a reactive multi-metric routing protocol for intra-infrastructure communications and a proactive multi-tree based routing protocol for communications with external networks. The proposed routing protocol enables forwarding real-time and streaming applications with QoS guarantee in a mesh wireless environment, by assigning a specific routing path for each defined service class. To this end, three different QoS service classes are defined, depending on the applications requirements. We analyze in this paper the simulation results of different scenarios conducted on the network simulator ns-3 to demonstrate the effectiveness of the HQMR protocol and to compare it to other routing protocols while forwarding real-time applications with QoS guarantee.     

Oblivious routing in wireless mesh networks

As new network applications have arisen rapidly in recent years, it is becoming more difficult to predict the exact traffic pattern of a network. In consequence, a routing scheme based on a single traffic demand matrix often leads to a poor performance. Oblivious routing (Racke in Proceedings of the 43rd annual IEEE symposium on foundations of computer science 43–52, 2002) is a technique for tackling the traffic demand uncertainty problem. A routing scheme derived from this principle intends to achieve a predicable performance for a set of traffic matrixes. Oblivious routing can certainly be an effective tool to handle traffic demand uncertainty in a wireless mesh network (WMN). However, a WMN has an additional tool that a wireline network does not have: dynamic bandwidth allocation. A router in a WMN can dynamically assign bandwidth to its attached links. This capability has never been exploited previously in works on oblivious routing for a spatial time division multiple access (STDMA) based WMN. Another useful insight is that although it is impossible to know the exact traffic matrix, it is relatively easy to estimate the amount of the traffic routed through a link when the routing scheme is given. Based on these two insights, we propose a new oblivious routing framework for STDMA WMNs. Both analytical models and simulation results are presented in this paper to prove that the performance—in terms of throughput, queue lengths, and fairness—of the proposed scheme can achieve significant gains over conventional oblivious routing schemes for STDMA based WMNs.     

Implementation of enhanced forward pointer-based mobility management scheme for handling internet and intranet traffic in wireless mesh network

To implement WMN, IEEE 802.11s has been developed. The routing protocol for selecting a path between two mesh stations in IEEE 802.11s is hybrid wireless mesh protocol (HWMP). But mobility of external stations has not been considered in IEEE 802.11s. For handling movement of clients, many mobility management schemes have been proposed. Some of such schemes are: ANT, Mesh Mobility Management (M\(^{3})\), Infrastructure Mesh (iMesh), SMesh, MEsh networks with MObility management (MEMO), Wireless mesh Mobility Management (WMM), Static Anchor Scheme, Dynamic Anchor Scheme, LMMesh, Session-to-Mobility-Ratio based Scheme and Forward Pointer-Based Mobility Management Scheme (FPBR). But none of the schemes except FPBR have been integrated with IEEE 802.11s for providing mobility support to the external stations. FPBR has been proposed to enhance IEEE 802.11s for providing mobility support to external stations, but it can support internet traffic only. In WMN both internet and intranet traffic to and from the external station is important. In this paper, an improved version of FPBR named Enhanced FPBR (EFPBR) Scheme has been introduced to handle both internet and intranet traffic. Both EFPBR and HWMP have been numerically analyzed. HWMP and EFPBR schemes are simulated and the performances are compared. From the performance comparison, it can be observed that EFPBR performs better than that of IEEE 802.11s concerning throughput, end-to-end delay, routing overhead and average handoff cost. The number of route management packets transferred per handoff measured from numerical analysis and simulation has also been compared.     

无线Mesh网络组播研究分析

介绍了无线Mesh网络(WMN)中的组播协议,并分析了为WMN设计组播协议时要注意的一些因素,如Mesh路由器的有效性、多信道和信道分配的影响、负载均衡、组播路由性能指标的选择、保证QoS的影响和跨层优化.最后,分析了目前研究中存在的问题,并对未来的研究提出了自己的看法.     

无线网格网中一种基于树的先验式路由协议

Wireless Mesh Network (WMN) is seen as an effective Internet access solution for dynamic wireless applications . For the low mobility of mesh routers in WMN, the backbone topography can be effectively maintained by proactive routing protocol. Preproposals like Tree Based Routing (TBR) protocol and Root Driven Routing (RDR) protocol are so centralized that they make the gateway become a bottleneck which severely restricts the network performance. We proposed an Optimized Tree-based Routing (OTR) protocol that logically separated the proactive tree into pieces. Route is partly computed by the branches instead of root. We also discussed the operation of multiple Internet gateways which is a main issue in WMN. The new proposal lightens the load in root, reduces the overhead and improves the throughput. Numerical analysis and simulation results confirm that the performance of WMN is improved and OTR is more suitable for large scale WMN.     

A kind of novel VPF‐based energy‐balanced routing strategy for wireless mesh network

Wireless mesh network (WMN) can sense information and realize end‐network transmission. It consists of numerous wireless sensors, the energy and communication ability of which are limited. A kind of novel VPF‐based energy‐balanced routing strategy for WMN has been presented in this paper. Most of the existing energy‐efficient routing strategy always forwards packets along the minimum energy path to the sink to merely minimize energy consumption, which causes an unbalanced distribution of residual energy among sensor nodes, and eventually results in a network partition. We design the energy‐balanced routing strategy by setting up a mixed virtual potential field in terms of depth and energy by using the physical potential concept. The strategy can force packets to move toward the sink through the dense energy area and protect the nodes, which has relatively low residual energy. By comparing to the other energy‐efficient routing strategy in our designed scenarios, the experimental results show that energy balance and throughput can be improved. Copyright © 2014 John Wiley & Sons, Ltd.     

A flow-based network monitoring framework for wireless mesh networks

As an extension of wireless ad hoc and sensor networks, wireless mesh networks recently were developed as a key solution to provide high-quality multimedia services and applications, such as voice, data, and video, over wireless personal area networks, wireless local area networks, and wireless metropolitan area networks. A WMN has a hybrid network infrastructure with a backbone and an access network and usually is operated in both ad hoc and infrastructure modes with self-configuration and self-organization capabilities. In this article, we review security challenges, attacks, and countermeasures in the physical, medium access control (MAC), and network layers of wireless mesh backbone and access networks. We then extend the concept of traffic flow from IP networks and define meshflow in wireless mesh networks. Based on this new concept, we propose a comprehensive framework to realize network monitoring, user and router profiling, application and service balancing, and security protection in wireless mesh backbone networks. Practical issues and design trade-offs for implementing the proposed framework in real systems also are discussed.     

无线网状网路由判据研究

无线网状网(WMN)相关技术的研究非常活跃,路由判据的设计是提高其性能的关键。WMN具有同时拥有移动节点和静态节点及每个节点可能配置多信道等特点。对路由判据的设计提出了特别的要求:必须保证网络的稳定性;保证最小权重路由有最佳性能;该路由可以通过多项式复杂度算法得到;得到的路由中无转发环路。研究了几种现有的路由判据,包括HOP、ETX、ETT、WC-ETT、MIC、mETX、ENT。MIC能较好适应WMN,但需要在自由因子的设定及网络中加入移动节点后的性能方面做改进。对路由判据的跨层、多准则设计是以后的研究方向,基于此文中也对几个改进方案进行分析。     

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。