Wireless mesh networks: a survey
Ian F. Akyildiz a, Xudong Wang
, Weilin Wang
Broadband and Wireless Networking (BWN) Lab, School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA b Kiyon, Inc., 4225 Executive Square, Suite 290, La Jolla, CA 92037, USA Received1 June 2004; received in revised form 1 November 2004; accepted 20 December 2004 Available online 1 January 2005
Abstract Wireless mesh networks (WMNs) consist of mesh routers and mesh clients, where mesh routers have minimal mobility and form the backbone of WMNs. They provide network access for both mesh and conventional clients. The integration of WMNs with other networks such as theInternet, cellular, IEEE 802.11, IEEE 802.15, IEEE 802.16, sensor networks, etc., can be accomplished through the gateway and bridging functions in the mesh routers. Mesh clients can be either stationary or mobile, and can form a client mesh network among themselves and with mesh routers. WMNs are anticipated to resolve the limitations and to signiﬁcantly improve the performance of ad hoc networks,wireless local area networks (WLANs), wireless personal area networks (WPANs), and wireless metropolitan area networks (WMANs). They are undergoing rapid progress and inspiring numerous deployments. WMNs will deliver wireless services for a large variety of applications in personal, local, campus, and metropolitan areas. Despite recent advances in wireless mesh networking, many research challengesremain in all protocol layers. This paper presents a detailed study on recent advances and open research issues in WMNs. System architectures and applications of WMNs are described, followed by discussing the critical factors inﬂuencing protocol design. Theoretical network capacity and the state-ofthe-art protocols for WMNs are explored with an objective to point out a number of open research issues.Finally, testbeds, industrial practice, and current standard activities related to WMNs are highlighted. Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Wireless mesh networks; Ad hoc networks; Wireless sensor networks; Medium access control; Routing protocol; Transport protocol; Scalability; Security; Power management and control; Timing synchronization
Corresponding author. Tel.:+1 425 442 5039. E-mail addresses: firstname.lastname@example.org (I.F. Akyildiz), email@example.com (X. Wang).
1389-1286/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.comnet.2004.12.001
I.F. Akyildiz et al. / Computer Networks 47 (2005) 445–487
1. Introduction As various wireless networks evolve into the next generation to provide better services, a keytechnology, wireless mesh networks (WMNs), has emerged recently. In WMNs, nodes are comprised of mesh routers and mesh clients. Each node operates not only as a host but also as a router, forwarding packets on behalf of other nodes that may not be within direct wireless transmission range of their destinations. A WMN is dynamically self-organized and self-conﬁgured, with the nodes in the networkautomatically establishing and maintaining mesh connectivity among themselves (creating, in eﬀect, an ad hoc network). This feature brings many advantages to WMNs such as low up-front cost, easy network maintenance, robustness, and reliable service coverage. Conventional nodes (e.g., desktops, laptops, PDAs, PocketPCs, phones, etc.) equipped with wireless network interface cards (NICs) can connect directlyto wireless mesh routers. Customers without wireless NICs can access WMNs by connecting to wireless mesh routers through, for example, Ethernet. Thus, WMNs will greatly help the users to be always-on-line anywhere anytime. Moreover, the gateway/bridge functionalities in mesh routers enable the integration of WMNs with various existing wireless networks such as cellular, wireless sensor,...