What’s up with wireless mesh networking?

Q: I’m considering providing Wi-Fi coverage over a large area that doesn’t have existing cabling. I’ve heard that mesh networks are good in these situations, but I don’t know much about them. What are they, and their associated benefits? Andrew, White River Junction, Vermont.

A: Mesh networks are a great wireless technology for situations where it is hard or costly to pull cables.

The most common mesh architecture for the commercial market consists of routing packets over wireless links to a central wired network. This architecture is an excellent choice for wireless ISPs (WISP) that want to create a wireless broadband pico cell network, such as 802.11 hot spots, over a large geographic area. Leveraging the unlicensed bands of 802.11, mesh technology can deliver high bandwidth at an order of magnitude lower cost than existing cellular technologies.

As a result, the cost of future mobile Internet access will be at a price point that the average person can afford, giving way to a whole new market for wireless devices and services, such as streaming video over handheld media players.

In the enterprise market, the mesh architecture lets IT departments extend wireless coverage to areas that do not have cabling infrastructure. In these situations, mesh access points integrate with existing WLAN access points to extend Wi-Fi coverage to areas not readily accessible by cables.

It is important to point out, however, that the addition of mesh access points can increase network latency. In an 802.11 environment, each wireless hop created when a packet travels between a client device and the wired network adds 1-2 milliseconds of delay.

As a result, careful design considerations need to be given to the size of the mesh network and the types of applications deployed.

One of the other concerns to date has been that mesh networks were proprietary. But recently, we have begun to see increasing efforts to standardize, with some vendors developing systems based on current 802.11 technologies. In fact, at the IEEE 802.11 Working Group meeting held January 11-16, a study group was formed to explore establishing an industry-recognized standard for wireless mesh networking. This is a significant step forward, as this wizard believes the use of mesh networks will grow considerably as standards take form. By expanding wireless coverage beyond today’s existing physical boundaries, mesh technology will provide a nice complement to existing 802.11 WLAN systems.