Why Wireless Mesh Networks?

In recent years, wireless networks became widely accepted as an alternative to wired networks for connecting enduser devices. Standardization and decreasing costs enabled their success in the mass-market and lately the wide-spread deployment in private households. However, such systems usually only bridge the distance between a base station and the end-user device wirelessly. Behind the base station, there is a more or less complex infrastructure based on traditional wired network technology. For example, the access points (AP) of a wireless local area network (WLAN) are generally interconnected by Ethernet cables.

Over the past years, an approach has received a great deal of attention that consistently adopts wireless network technology: mobile ad-hoc networks (MANET). MANETs are spontaneously formed by wireless mobile nodes having no need for a preexisting infrastructure like the wireless APs. Here, nodes communicate directly with other nodes within their wireless transmission range. In order to communicate with the remaining nodes, they use intermediate nodes as relays. In other words, every node acts as a host as well as a router and, therefore, contributes both to the network architecture and to the routing. MANETs are decentralized networks, there are no special nodes whose failure might tear down the network completely. Thus, it is possible to establish MANETs in situations where traditional wired infrastructure is damaged, or does not even exist, and cannot be (re-)established in a timely manner. Typical application scenarios are the deployment of relief units in disaster areas or of combat units in battlefields.

Despite intensive research effort, MANETs have not become widely accepted by the mass market, yet. This is comprehensible insofar as the above and frequently mentioned application scenarios are very specific and mainly either military-driven or solely applicable in special cases. However, the masses demand versatile networks providing them high bandwidth and access to the Internet [RufStuCla+05] .

There is a new class of networks fulfilling these requirements, the so-called wireless mesh networks (WMN) [AkyWanWan05]. Even though MANETs and WMNs share the same idea, the latter do not have the aim to establish utterly self-sufficient, isolated networks without any pre-existing infrastructure. In contrast, WMNs can be integrated into wired networks and can easily extend them at low cost without losing the mobility or flexibility of MANETs.