MMDS, LMDS: A boon to local loop competition

One of the most promising "great equalizers" in the access network is wireless local loop technology, also known as broadband wireless access. Think about it: New competitive carriers can deploy wireless networks in a fraction of the time it takes to build wired infrastructures. And the availability limitations of DSL and cable modem services aren't an issue in wireless networks. BWA holds the promise of getting high-speed, competitively priced services to enterprise sites, remote offices, and, well, just about anybody really fast.

Two primary technologies are being rolled out to enable BWA:

• Local multipoint distribution services (LMDS), a line-of-sight technology running in the 28 GHz band. LMDS is most suited for densely populated urban areas where it is difficult and expensive to deploy additional or new wired infrastructures. Typical speeds are 45M bit/sec downstream in a point-to-multipoint configuration. However, LMDS has the potential to exceed OC-3 (155M bit/sec) speeds. Distances between sites are limited to 4 kilometers.

• Multichannel multipoint distribution service (MMDS) operates in the 2 GHz to 3 GHz band, is less susceptible to interference than LMDS, and has no line-of-sight requirements. MMDS can support greater distances than LMDS - up to 30 miles between sites. The tradeoff is that MMDS is slower, delivering downstream speeds in the neighborhood of 10M bit/sec.

With both technologies, an antenna and radio are installed on the roof of a business' site and are connected by coaxial cable to customer premises equipment in the LAN wiring closet.

Commercial service availability is imminent. WorldCom has been conducting MMDS service trials with schools, residential and business customers in Boston; Dallas; Jackson, Miss.; Baton Rouge, La.; and Memphis, Tenn., using equipment from Cisco and Motorola. Meanwhile, Cisco has said it plans to begin commercially shipping LMDS and MMDS interfaces for its routers by midyear - which sounds like any day now. The move could prove to be a major stepping stone for service provider deployments.

Joanie Wexler is an independent networking technology writer/editor in Campbell, Calif., who has spent most of her career analyzing trends and news in the computer networking industry. She welcomes your comments on the articles published in this newsletter, as well as your ideas for future article topics. Reach her at joanie@jwexler.com.

Network World Wireless archive
Past newsletters.

Statistics and surveys
from the Cellular Telecommunications Industry Association

Cisco MMDS press release

Sprint is bringing its fixed wireless services online
Network World, 05/10/00.

MCI WorldCom prepping fixed wireless service
Network World, 03/08/00.

Archive of Network World on Wireless newsletters