Wireless Hacks

Hack 5 802.16: Long Distance Wireless Infrastructure

The long awaited Municipal Area Network protocol is on the way, but isn't here just yet.

Approved on December 6, 2001, 802.16 promises to be the answer to all of the shortcomings of long distance applications that people have encountered using 802.11 protocols. It should be pointed out that the 802.11 family was never intended to provide long distance, metropolitan-area coverage (although I'll show you some examples of people doing exactly that). The 802.16 specification is specifically designed for providing wireless infrastructure that will cover entire cities, with typical ranges measured in kilometers. It will use frequencies from 10 to 66 GHz to provide commercial quality services to stationary locations (i.e., buildings). In January 2003, a new extension (802.16a) was ratified, which will operate in the 2 to 11 GHz range. This should help significantly with line-of-sight requirements of the extremely short waves of 10 to 66 GHz. Realistically, actual equipment that implements 802.16 is just now coming to market, and will likely be priced well above the consumer-grade equipment of the 802.11 family.

Pros

• 802.16 is designed for long-range networking, likely providing ranges of 20 to 30 kilometers.

• Very high speed for fixed wireless, probably about 70 Mbps.

Cons

• Shorter wavelengths of 10 to 66 GHz are more susceptible to signal fade due to environmental conditions (such as rain).

• Many bands used by 802.16 and 802.16a are licensed spectrum.

• It's just not available yet.

Recommendation

It will be interesting to see the 802.16 MAN story as it evolves, but it's too early to tell how this technology will fare. Fujitsu is currently developing an 802.16a chipset that it expects to have ready sometime in 2004, and is currently targeting a price tag of about $300. 802.16 will certainly be a welcome technology for long distance point-to-multipoint applications, which are difficult to implement effectively using 802.11. But unfortunately, the hardware isn't available to play with yet.