The Truth About Omnis

[BackatchaBandit]

I found an interesting and well written article that outlines some of the problems inherent in WiFi, particularly regarding meshing / Community Area Networks:

At first glance omni-directional antenna seem to be the obvious choice for wireless mesh networks, they allow a single wireless interface to simultaneously communicate with many neighbours, expanding the mesh coverage. Obviously all the devices are on the same wireless channel as they need to communicate with one another. However using omnis will lead to very poor throughput in the network...

The Truth About Omnis (SOWN - UK)

[Thorn]

The Hidden Node problem has long been known to those who have radio experience. Part of the problem is exactly what the author states: "It's very easy to think of 802.11b as ethernet, especially if you're a network oriented person like me(as opposed to a radio oriented one)." He and many others are attempting to do something with radios when they don't fully understand how the media itself works. In addition, the 802.11/a/b/g standard was never designed for much of what people have tried to do with it over the last few years. While there's nothing wrong with that (and alot that's right!) somethings are not going to work.

Many so-called "mesh" networks aren't really a mesh at all. In many cases they tend to be a loose collection of 802.11 APs at best, and unfortunately some are little more than a bunch of co-interefering APs. It can be done to a certain extent using proper cell design as shown on the linked "Topology" page, but again, it's not really what 802.11 was designed for, and the logistics can be a nightmare.

Some true radio network meshs exist in the ISM band, but the controllers in the AP have different firmware which is meant to address this issue. Most tend to be proprientary, costly or both.