The IEEE 802.16 (10GHz+ licensed flavor) and 802.16a (<10GHz unlicensed spectrum flavor) broadband wireless access standards are headed toward market, but won't really launch until the second half of this year. Intel and Fujitsu have announced silicon, and Intel has specifically said it will be shipping in 2H04, so they should be sampling now. Of the various vendors supporting the WiMax Forum 802.16 industry group, Alvarion and Airspan have specifically said they would be building systems on the Intel silicon, and Airspan has (pre)announced its product.
Other notable vendors that have generally indicated they will do 802.16/a products include Aperto, Beamreach,Vyyo and Wi-LAN. Generally their public endorsements of the standard are very short on specifics: All of these companies face the possibility that customers may delay purchase of current products while waiting for 802.16 to arrive. The one company claiming to be shipping '802.16 interoperable' products right now is Redline Communications:
"Announced in October 2003, the AN-100 is an IEEE 802.16(a) standards based fixed wireless system that is a high performance carrier class solution designed to support high capacity backhaul and access connections through point to point and point to multipoint deployments."The compatibility claim should probably be treated with some caution, since I believe the Redline system was built on their own silicon, and interoperability testing with the larger vendors is not likely to have occurred yet.
The original 802.16 specification did not specifically support mobility of client devices. It does have an adaptive PHY layer that can shift modulation schemes on a client-by-client and frame-by-frame basis, from 64QAM down to QPSK, based on RF propagation characteristics. Given low ground speeds, this adaptation alone might be sufficient to sustain some mobility. However, there is no provision at all for cell-like handoff in the 802.16/a specs; a single base station is assumed at all times. Ranges up to 40km have been discussed for 802.16, but obviously there hasn't been much stress testing of this claim.
There is a new subcommittee in progress, 802.16e, which will add a mobility specification, including base-station handoff. Depending on who you believe, this might be mostly aimed at walking speed individual users, or might also include handoff at normal vehicular speeds - which seems more sensible if one is to do it at all. One reason for the ambiguity in the 802.16e design space is a perceived conflict with another IEEE BWA group, 802.20. This was from the start intended to be an OFDM-based system designed for mobility, to compete with 3G (W-CDMA, CDMA2000) cellular carrier systems. Particularly, Flarion with its flashOFDM technology was associated with the creation of this group, and is one of the few existing BWA startups that has managed to avoid having its proprietary offering obsoleted (in the eyes of the market) by 802.16. That said, the amount of support behind 802.20 is modest compared with WiMax. The notable vendors pushing this group are Flarion, ArrayComm, and Navini, all private companies. While it's worth keeping an eye on this group, it is likely to come to market later and have more modest vendor support.
A few relevant articles may found in Wireless Week, ISP Planet, and X-Change.