无线网状网组网技术及实验研究

面对日益增长的高速无线因特网接入需求,传统的无线接入方式,如蜂窝网、无线局域网（WLAN）面临许多挑战,而无线网状网（WMN）作为因特网“最后一公里”接入方案,提供一种灵活而低成本的多跳通信,也将成为各种无线网络融合的主要技术。针对这一极具发展前途的网络结构,从WMN的两种典型应用出发,文章从网络配置、功率控制、移动性管理和接入控制以及路由协议设计等方面说明了WMN组网中的相关问题和技术,对WMN与移动自组织（Ad hoc）网路由协议的设计进行了对比,并给出了一种基于WLAN和第二层交换技术的WMN试验床实现方案。     

无线Mesh网络与IEEE802系列标准

无线宽带接入系统发展迅速,但带宽容量低、覆盖范围小等缺点限制了它的进一步发展。作为“最后一公里”宽带无线接入非常重要的技术之一。无线Mesh网络（WMN）可以和多种无线网络系统,如无线局域网（WLAN）、无线个域网（WPAN）以及无线城域网（WMAN）等相结合,改善无线网络的性能,提高网络的覆盖范围。随着无线Mesh网络技术的厂泛应用,IEEE802的相关标准组正在致力于推动WMN技术的发展,制订相关的技术标准。目前,WMN标准已经出现在IEEE802．11s、80215、802．16、802．20中。     

Wireless Mesh Network and IEEE 802 Standards

Although the wireless broadband access system is developing rapidly, its development is limited due to some disadvantages , such as small capacity of bandwidth and small coverage . The Wireless Mesh Network (WMN) is one of the important technologies for "last mile "broadband wireless access . The WMN can integrate with multiple wireless systems , such as Wireless Local Area Network (WLAN), Wireless Personal Area Network (WPAN), and Wireless Metropolitan Area Network (WMAN), to improve the performance of the wireless network and enlarge the coverage range . With the wide applications of the WMN, the IEEE 802 standard group is devoted to promoting the development of the WMN technology and establishing the related technical standards . At present, WMN standards have appeared in IEEE 802.11s , 802.15, 802.16, and 802.20.     

无线网格网关键技术及其应用

无线网格网(WirelessMeshNetwork,WMN)是一种新型的无线宽带接入网络,它融合了无线局域网(WirelessLAN,WLAN)和AdHoc网络的优势,是一种大容量、高速率、覆盖范围广的网络,成为宽带接入的一种有效手段。本文主要介绍了无线网格网的研究现状、结构、关键技术以及与其他通信网络的区别,最后介绍了两种无线网格网的技术方案以及应用前景。     

基于无线Mesh网络技术构建无线城市

无线Mesh网络(WMN)可以和多种无线网络系统,如无线局域网(WLAN)、无线城域网(WMAN)等相结合,改善无线网络的性能,提高网络的覆盖范围.以WMN网络技术在IEEE 802系列标准中的发展为基础,提出了一种无线城市的覆盖方案,最底层网络覆盖采用WiFi+wireless Mesh技术,WiMAX网络与WiFi...     

无线Mesh网网络层和MAC层相关研究

随着无线网络技术的发展,无线mesh网凭借其多跳通信能力为拓宽WiFi网络的覆盖率提供了有效的途径。利用低发射功率来提高覆盖率和容量的能力,使其在普遍存在的宽带接入中扮演重要角色。凭借其独特的优势,WMN发展非常迅速,并广泛应用于众多领域。为了更好的说明WMN领域存在的挑战,详细描述了无线mesh网的MAC层和网络层研究状况,并且提出了可能提高多跳网络吞吐量的新协议。     

无线Mesh技术和网络

无线网状网（WMN）是近年被高度重视和快速发展的新型网络技术,支持宽带高速多媒体业务服务。文章就无线Mesh网络技术和应用进行讨论,综述无线Mesh网络的发展由来、基本技术、典型应用和现在的发展。随着未来无线分布技术和无线分布网络的发展,无线Mesh技术和网络将会成为无线移动通信的基本网络技术和网络结构,渗透到各种无线网络中,发挥更大作用。     

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.     

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.     

Proportional bandwidth allocation with consideration of delay constraint over IEEE 802.11e-based wireless mesh networks

Wireless mesh networks (WMNs) extend the limited transmission coverage of wireless LANs by enabling users to connect to the Internet via a multi-hop relay service provided by wireless mesh routers. In such networks the quality of experience (QoE) depends on both the user location relative to the Internet gateway and the traffic load. Various channel access or queue management schemes have been proposed for achieving throughput fairness among WMN users. However, delay and bandwidth utilization efficiency of such schemes may be unacceptable for real-time applications. Accordingly, the present study proposes a proportional bandwidth allocation scheme with a delay constraint consideration for enhancing the QoE of users of WMNs based on the IEEE 802.11e standard. An analytical model of the proposed scheme is provided. Moreover, the performance of the proposed scheme is systematically compared with that of existing bandwidth allocation methods. The simulation results show that the proposed scheme outperforms previously proposed schemes in terms of both an improved throughput fairness among the WMN users and a smaller end-to-end transmission delay.     

新一代无线Mesh网络

无线Mesh网络是下一代无线网络的关键技术之一,近几年得到了人们的广泛关注和快速发展.为了以低成本的代价实现无处不在的高速Intemet,新一代无线Mesh网络的发展势在必行.新一代无线Mesh网络旨在能够提供高性能和高可靠性的服务.本文介绍了传统无线Me8h网络的优缺点,分析了研究现状,并阐诛了新一代无线Mesh网络面临的技术挑战.     

Wireless Mesh Architecture for IP-Based Base Stations

Combining the performance advantages of both Wireless Local Area Network (WLAN) and Ad hoc network, Wireless Mesh Network (WMN) is characterized by large capacity, high rate and wide coverage. It has become an effective means for broadband wireless access and can be applied flexibly in various wireless environments. The wired connections between base stations in traditional cellular mobile communications systems can no longer satisfy the requirements for flexible deployment, low cost, high scalability and good reliability. The wireless Mesh architecture for IP-based base stations is thus introduced as an optional solution to support the flat and simplified next generation mobile communications networks. The key technologies used to support self-organization of IP-based base stations involve several aspects, including on-demand self-organization of base stations, joint radio resource scheduling mechanism, routing, security and network management.     

Enhanced Active Queue Management for Multi-hop Networks

Wireless networks play a very important role in today’s modern world, convincingly surpassing the wired infrastructure in terms of popularity. Hence, it is important to ensure that services which access wired networks should also be accessible using a wireless network without any performance degradation. One of the most common variants in wireless communications is the Wireless Mesh Network (WMNs). WMNs exploit multi-hop wireless communications between wireless access points. Hence, the effective bandwidth decreases as the number of hops increases in a WMN, thus increasing latency and resulting in reduced performance. This may be due to spatial contention, multipath fading, interference or inefficient queuing mechanisms etc. Here we take queuing mechanisms into consideration and study the QMMN algorithm (Queue Management for Multi-hop Networks) which tends to improve throughput, fairness and reduce global synchronization problems. Based on our study, we implement a modified version of the QMMN algorithm, otherwise called the Enhanced QMMN (EQMMN) algorithm. EQMMN can be considered an effective algorithm which solves the problem of fairness between flows (either responsive or unresponsive) and eventually improves TCP throughput at wireless access points. Our experimental results prove that EQMMN algorithms have better performance characteristics such as throughput (TCP) and fairness index compared to QMMN algorithms.     

On Delay Performance and Burst Assembly for Wireless Mesh and Optical Burst Switching Converged Metro Area Network

Wireless Mesh Networks (WMN) have attracted increasing attention from the research community as a high-performance and low-cost solution to last-mile broadband Internet access. On the other side, Optical Burst Switching (OBS) is a promising access technology that uses optical fiber with burst switching paradigm. In this paper, we propose a novel Metropolitan Area Network (MAN) architecture, called Optical Burst Wireless Mesh Architecture (OBWMA) which integrates WMN at the user access side and OBS at the core of the MAN. OBWMA aims to combine advantages of both WMNs and OBS networks, such as large coverage at low cost and bandwidth availability. We specify the details of the interconnection and the internetworking of WMNs and the OBS network in OBWMA. Moreover, we develop an analytical model to compute the end-to-end delay in OBWMA in order to support flow requests with delay constraints. Furthermore, we propose a Control Bridge (CB) that ensures Quality of Service (QoS) mapping at the border between the WMN and the OBS parts. Also, we propose a burst assembly scheme, called Adaptive Hybrid Burst Assembly scheme (AHBA). Simulation results using ns-2 demonstrate the feasibility of OBWMA and the validity of our analytical model.     

基于HWMP的先应树状路由算法研究

无线网状网是一种新兴的宽带无线网络接入技术,支持不同应用场景的无线接入。IEEE802.11s标准定义了一种默认的路由选择算法,称为混合无线网状网协议(HWMP)。HWMP将把树状路由为基础的先应路由模式和按需路由模式相结合。对先应路由模式进行改进,以减小网络开销,增强网络性能。从仿真结果可以看出,改进后的算法在数据包到达率、平均端到端时延和吞吐量指标上达到了更佳的性能。     

Wireless Mesh Technology and Network

Wireless Mesh Network (WMN) has been actively researched and developed as a new network technology to support broadband high- speed multimedia services . This paper discusses WMN technology and applications , and introduces the basic technologies , typical applications and current development of the WMN. With the future development of wireless distribution technology and network, wireless Mesh technology and network will become the key networking technology and architecture of wireless mobile communications , and will be widely used in various wireless networks with more important roles .     

Reliability Strategies for Data Transmission in Wireless Mesh Network

Wireless Mesh Network (WMN) is a new-type wireless network. Its core idea is that any of its wireless equipment can act as both an Access Point (AP) and a router. Each node in the network can send and receive signals as well as directly communicate with one or several peer nodes. One important issue to be considered in wireless Mesh networks is how to secure reliable data transmission in multi-hop links. To solve the problem, the 3GPP system architecture proposes two functionalities: ARQ and HARQ. This paper presents two HARQ schemes, namely hop-by-hop and edge-to-edge, and three ARQ schemes: hop-by-hop, edge-to-edge, and last-hop. Moreover, it proposes three solutions for WMNs from the perspective of protocol stock design: layered cooperative mechanism, relay ARQ mechanism and multi-hop mechanism.     

IP化基站无线Mesh组网构架

无线网状网（WMN）融合了无线局域网（WLAN）和Ad Hoc网络的性能优势,具有容量大、速率高、覆盖范围广等特点,成为宽带无线接入的一种有效手段,可以灵活地应用于多种无线环境。目前,蜂窝移动通信系统中各基站间的有线连接,使得传统的蜂窝移动通信系统难以满足部署方便、成本低廉、高可扩展性、高可靠性等指标。为适应下一代移动通信网络扁平化、简单化的发展趋势,IP化基站的无线Mesh组网架构是可选方案之一。支持IP化基站自组织的关键技术包括按需的基站自组织技术、联合无线资源调度机制、路由技术、安全技术、网络管理技术等。     

Multi-hop Delay Performance in Wireless Mesh Networks

Wireless Mesh Network (WMN) technology is an attractive solution to meet the demand of broadband network access anywhere and anytime. In order to effectively support delay-sensitive applications such as video streaming and interactive gaming in a WMN, it is crucial to develop feasible methodologies and techniques for accurately analyzing, predicting and guaranteeing end-to-end delay performance over multi-hop wireless communication paths. In this paper, we extend the link-layer effective capacity model and derive a lower bound of delay-bound violation probability, or complementary cumulative distribution function, over multi-hop wireless connections. A fluid traffic model with cross traffic and a Rayleigh fading channel with additive Gaussian noise and Doppler spectrum are considered in our study. The average multi-hop delay and jitter performance bounds are also obtained. Analytical results are verified by extensive computer simulations under different traffic load and wireless channel conditions. We find that multi-hop delay performance is much more sensitive to traffic load and maximum Doppler rate than traffic correlation.     

Design and analysis of intrusion detection systems for wireless mesh networks

Intrusion is any unwanted activity that can disrupt the normal functions of wired or wireless networks. Wireless mesh networking technology has been pivotal in providing an affordable means to deploy a network and allow omnipresent access to users on the Internet. A multitude of emerging public services rely on the widespread, high-speed, and inexpensive connectivity provided by such networks. The absence of a centralized network infrastructure and open shared medium makes WMNs particularly susceptible to malevolent attacks, especially in multihop networks. Hence, it is becoming increasingly important to ensure privacy, security, and resilience when designing such networks. An effective method to detect possible internal and external attack vectors is to use an intrusion detection system. Although many Intrusion Detection Systems (IDSs) were proposed for Wireless Mesh Networks (WMNs), they can only detect intrusions in a particular layer. Because WMNs are vulnerable to multilayer security attacks, a cross-layer IDS are required to detect and respond to such attacks. In this study, we analyzed cross-layer IDS options in WMN environments. The main objective was to understand how such schemes detect security attacks at several OSI layers. The suggested IDS is verified in many scenarios, and the experimental results show its efficiency.