It's likely you've accessed the Internet via WLAN (wireless local area network) at an airport, or in your office. While the device you're using, such as a laptop or PDA, is wirelessly connecting to one of many APs (access points) on the WLAN, each AP must have a physical, wired connection to a network. The difference in a wireless mesh network, shown in Figure A, is the majority of the APs don't have a hard-wired connection.

FIGURE A

A wireless mesh network. Click picture for a larger image.

Instead, they route traffic wirelessly, and are connected to the network through a few, select, wired nodes.

Why is this important? In a large city, hundreds or even thousands of nodes would be needed. Think about the significant amount of time and expense involved in installing all the cabling to create a wired connection for each of the APs, let alone the challenges and disruption to businesses and residents given the congested confines of city landscapes.

Conversely, all that's needed for a mesh network is installation of the AP. In most cases, they're quickly and easily mounted on light poles or traffic signals, which have ready supplies of power. The ease of installation and low cost make wireless mesh networks an attractive choice; however, the ultimate success of these installations lies in the planning and design of the network.

Target markets
Generally, wireless mesh networks are best suited for large open areas, both indoors and outdoors, and where network cabling doesn't exist and is costly to install. As mentioned earlier, a number of local governments are implementing wireless mesh networks, and most are initially focused on providing high speed voice and data communication services to police, fire, medical emergency teams, and other government employees. In essence, the mesh network brings the office to the field. Cities are also evaluating the benefits of providing residents and visitors with Internet access in their homes or public areas.

Additional outdoor uses include university settings, to provide campus-wide coverage for faculty and students, or temporary settings, such as music festivals or disaster recovery situations. Potential indoor implementations include large manufacturing operations, distribution facilities, and healthcare operations. Wireless mesh networks are ideal for these situations because the large size of the facilities makes installing cable costly.