1、 A Survey on Wireless Mesh Networks IAN F. AKYILDIZ, GEORGIA INSTITUTE OF TECHNOLOGY XUDONG WANG, KIYON, INC. Abstract Wireless mesh networks (WMNs) have emerged as a key technology for next-generation wireless networking. Because of their advantages over other wireless networks, WMNs are undergoing
2、 rapid progress and inspiring numerous applications. However, many technical issues still exist in this field. In order to provide a better understanding of the research challenges of WMNs, this article presents a detailed investigation of current state-of-the-art protocols and algorithms for WMNs.
3、Open research issues in all protocol layers are also discussed, with an objective to spark new research interests in this field. Introduction Wireless mesh networks (WMNs) are dynamically self-organized and self-configured, with the nodes in the network automatically establishing an ad hoc network a
4、nd maintaining the mesh connectivity. WMNs are comprised of two types of nodes: mesh routers and mesh clients. Other than the routing capability for gateway/bridge functions as in a conventional wireless router, a mesh router contains additional routing functions to support mesh networking. Through
5、multi-hop communications, the same coverage can be achieved by a mesh router with much lower transmission power. To further improve the flexibility of mesh networking, a mesh router is usually equipped with multiple wireless interfaces built on either the same or different wireless access technologi
6、es. In spite of all these differences, mesh and conventional wireless routers are usually built based on a similar hardware platform. Mesh routers have minimal mobility and form the mesh backbone for mesh clients. Thus, although mesh clients can also work as a router for mesh networking, the hardwar
7、e platform and software for them can be much simpler than those for mesh routers. For example, communication protocols for mesh clients can be light-weight, gateway or bridge functions do not exist in mesh clients, only a single wireless interface is needed in a mesh client, and so on. In addition t
8、o mesh networking among mesh routers and mesh clients, the gateway/bridge functionalities in mesh routers enable the integration of WMNs with various other networks. Conventional nodes equipped with wireless network interface cards (NICs) can connect directly to WMNs through wireless mesh routers. C
9、ustomers without wireless NICs can access WMNs by connecting to wireless mesh routers through,for example, Ethernet. Thus, WMNs will greatly help users to be always-on-line anywhere, anytime. Consequently, instead of being another type of ad-hoc networking, WMNs diversify the capabilities of ad-hoc
10、networks.This feature brings many advantages to WMNs, such as low up-front cost, easy network maintenance, robustness, reliable service coverage, etc. Therefore, in addition to being widely accepted in the traditional application sectors of ad hoc networks, WMNs are undergoing rapid commercializatio
11、n in many other application scenarios such as broadband home networking, community networking, building automation, high speed metropolitan area networks, and enterprise networking. To date, several companies have already realized the potential of this technology and offer wireless mesh networking p
12、roducts. A few testbeds have been established in university research labs. However, for a WMN to be all it can be,considerable research efforts are still needed. For example,the available MAC and routing protocols are not scalable；throughput drops significantly as the number of nodes or hops in WMNs
13、 increases. Thus, existing protocols need to be enhanced or re-invented for WMNs. Researchers have started to revisit the protocol design of existing wireless networks,especially of IEEE 802.11 networks, ad hoc networks, and wireless sensor networks, from the perspective of wireless mesh networking.
14、 Industrial standards groups, such as IEEE 802.11, IEEE 802.15, and IEEE 802.16, are all actively working on new specifications for WMNs. In this article we present a survey of recent advances in protocols and algorithms for WMNs. Our aim is to provide a better understanding of research challenges o
15、f this emerging technology. The rest of this article is organized as follows. The network architectures of WMNs are first presented, with an objective to highlight the characteristics of WMNs and the critical factors influencing protocol design. A detailed study on recent advances of WMNs is then carried out, with an emphasis on open research issues. The article concludes with final remarks.
