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MANs to Go Walkabout

The Institute of Electrical and Electronics Engineers Inc. (IEEE) is working on a new iteration of the 802.16 wireless metropolitan area network (MAN) standard that will enable base stations to connect with mobile as well as stationary devices (see IEEE Extends 802.16 Standard).

Current 802.16 standards define only how base stations can connect to stationary wireless modems. This "mobile" version, called 802.16e, will specify how devices equipped with compliant modems may wander about among base stations without losing their wireless connection.

Why does this matter? For one thing it would allow service providers to offer wireless "last mile" services to homes and offices at speeds up to 10 Mbit/s -- with the added bonus of mobility within the coverage area. (For instance, someone could access the Internet from their laptop from home, then take the device into White Castle for a steamed burger, then pop into the office for a dump -- all the while enjoying uninterrupted high-speed service).

For another, it means that carriers would have an alternative to 802.11 for large-scale public access rollouts: university campuses, city centers, sports arenas, and the like.

802.16e will be backwards compatible with the existing standard, allowing vendors to add mobility features to their existing fixed wireless network products, according to Dr. Roger Marks, chair of the IEEE 802.16 working group on broadband wireless access.

While the "mobile" version is still under development, the IEEE has just ratified the 802.16a version of the wireless MAN standard. Unlike the original 802.16 standard (for wireless line-of-sight deployments), this version supports fixed, non-line-of-sight usage for use in the 2GHz to 11GHz bands, although Marks says the "prime unlicensed bands for 802.16a are at 5 to 6 GHz."

Unstrung wondered (mused, really) if there could be interference issues if operators deploy both 802.11a wireless LAN and 802.16a wireless MAN systems in the same vicinity. "You could run into interference issues between 5 GHz 802.16 and 802.11a," says Marks. "This is one of the problems of unlicensed bands. However, there are several 5GHz bands, and with different preferences for indoor versus outdoor use. So, even in the 5GHz case, there are compatible scenarios." However, there is currently no standard capability for 802.11 access points and 802.16 base stations to hand off to each other, so combining WLAN/MAN systems could prove to be tricky.

Marks says there were discussions at the IEEE in November about creating a generic 802. interface. This would enable handoff among wired Ethernet networks, wireless MAN, wireless LAN, and Bluetooth personal area networks (PANs). He expects more discussions on this topic this year.

The 802.16 specification is backed by equipment vendors such as Nokia Corp. (NYSE: NOK) -- a company that is actually based in Finland, believe it or not -- as well as chipmakers such as Intel Corp. (Nasdaq: INTC). "Intel has expressed very strong enthusiasm and support for the standard during the last few weeks," Marks comments.

So when will products using the standard arrive? "I'm not exactly sure," Marks clarifies. "They could be available by the end of 2003."

Marks expects typical implementations of the specification to provide data transfer rates of 10 Mbit/s and a coverage range of three to five miles. However, he stresses there are a lot of different variables with potential 802.16a rollouts, so the data transfer speeds and range offered by 802.16a networks may vary widely.

— Dan Jones, Senior Editor, Unstrung
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