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Part 3 Wireless Broadband Networks Handbook: 3G, LMDS & Wireless Internet Chapter 7: Local Multipoint Distribution Service (LMDS) Design Technology December 3, 2001 Brought to you by:
LMDS By comparison, initial tests by Hewlett Packard (HP, Palo Alto, CA) suggest that average residential users of LMDS will be able to receive data rates of 35 to 58 Mbps downstream, whereas commercial users will be able to attain rates of 51.84 to 155.52 Mbps (Sonet OC-1 to OC-3). Only a fiberoptic link to the home has greater capacity than LMDS, and deployment of that technology is unfeasible in the short term. At peak capacity, each subscriber to an LMDS system is expected to obtain results of at least 7 Mbps downstream and 1 Mbps upstream. Actual performance will be lower than quoted because these tests were based on full use of the 1300-MHz spectrum, but holders of A-block licenses (1150 MHz) will still be able to provide blistering data rates, CATV service, and telephony to their customers. LMDS will be relatively inexpensive to install at a cost of about $150 per premise passed, but infrastructure must be built from scratch, and attractive sites for towers may be difficult to come by. Basic CPE is expected to cost about $900 initially.
Evaluation Industry support has flooded behind cable modem and ADSL technologies. Low-cost chipsets and ASICs are available for platforms, and the technologies boast an impressive list of supporters, including Lucent Technologies (Murray Hill, NJ), 3Com (Santa Clara, CA), Analog Devices (Norwood, MA), Compaq (Houston, TX), Intel (Santa Clara, CA), Microsoft (Redmond, WA), Motorola (Schaumburg, IL), Ericsson (Sweden), NEC (Japan), and so on. Members of the computing industry in particular seem to be supporting ADSL, and to a lesser extent cable modems, as a means of delivering multimedia content to homes and businesses (a vehicle to justify the purchase of faster processors, greater storage capacity, and new software). This multibillion dollar industry has a lot to gain from the success of broadband delivery, and logic suggests that its members will go to great lengths to bring the most probable broadband technologies to the mass market. ADSL seems to be that technology. LMDS is not as fortunate. Only a few companies have publicly committed to supporting the platform, and those which have, with the exception of HP, lack the distribution, name-brand awareness, and financing that supporters of ASDL and cable modems possess. The difference is likely to result in LMDS CPE that cost more than and lacks the distribution of cable and ADSL modems. In addition, there will be lower visibility for LMDS. Time also could be an issue. If cable modem and ADSL services become widely accessible within the next 2 years, then deployment of LMDS could prove unattractive in areas that already possess other alternatives. The cost per actual subscriber of LMDS infrastructure would shoot to over $3000 if penetration falls below 17 percent, and high levels of penetration could be tough to come by if 38-GHz radio, ADSL, fiberoptic links, satellite systems, and cable modems are already in place. Thus, what will happen to LMDS? Only time can really tell. There are a number of variables that could drastically alter the market and the fortunes of LMDS providers. ADSL and cable modem deployment could lag considerably behind expectations, and satellite and many LMDS operators may not even build out their networks. However, developments in the market today suggest that leading LMDS auction winners will deploy networks and that these service providers will concentrate their efforts on business and well-to-do residential customers. The high cost of CPE will preclude deployment to other residential areas, at least initially. LMDS will face stiff competition from established and incipient technologies. And this is anticipated to cause LMDS to fall considerably short of the FCC's vision of it as a universal high-powered competitor to existing cable operators and ILECs. It is unlikely that LMDS will come close to the FCC's mandate for significant coverage of operating areas in the short term, and this decree could prove to be unfeasible even in the long term. Yet, despite this, LMDS operators could be very successful in their own right. It is not LMDS's ability to succeed that really needs to be questioned but rather its ability to live up to the hype that surrounds it. In all, the technology's greatest shortcoming could prove to be the unrealistic expectations that have been cast on it.
Competing Technologies Two primary technologies are being rolled out to enable BWA. The first has been discussed in this chapter quite extensively: 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 45 Mbps downstream in a point-to-multipoint configuration. However, LMDS has the potential to exceed OC-3 (155 Mbps) speeds. Distances between sites are limited to 4 km. The second primary technology—multichannel multipoint distribution service (MMDS)—operates in the 2- 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 10 Mbps. 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. Also, commercial service availability is imminent. WorldCom has been conducting MMDS service trials with schools and residential and business customers in Boston, Dallas, Jackson, Mississippi, Baton Rouge, and, Memphis 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.
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