4.3: MMDS and LMDS

While WiFi is a Local Area Network (LAN) technology, meant to cover a house or office, a number of Metropolitan Area Networks (MAN), which can cover a whole community or large rural area, are also in operation. A cell phone tower is actually a MAN because its signal has a radius in the tens of kilometres, which can provide network access to a large area. A number of other wireless MANs also live on Canada's antenna towers, the most significant of which are MMDS, LMDS, and proprietary systems like Motorola Canopy.

Multichannel Multipoint Distribution Service (MMDS, or sometimes MDS) has been around for at least a couple of decades and, until recently, was used exclusively for wireless distribution of cable television. MMDS operates over licensed frequencies at 2.1 GHz and from 2.5 to 2.69 GHz [72: 135-136]. The fact that it is licensed means that it's a lot more difficult for a company to go into an area and set up an MMDS network than it is to set up an unlicensed network. Often, a couple of years dealing with Industry Canada and the CRTC is required and license fees must be paid. In 1998, MMDS was opened up for bidirectional data services by the FCC and Industry Canada, but the technology is still used primarily in niche television distribution installations. Look Communications, Inc. launched an MMDS network in Southern Ontario Figure 27: Coverage area of Look MMDS Network [21]and Quebec in 1997, one of the first and one of the only in existence in Canada. Look installed 25km-range MMDS antennas on towers and tall buildings throughout Milton, Barrie, Aurora, Oshawa, Hamilton, Ottawa, Quebec City and Montreal, reaching many of the under-served homes and businesses in the rural areas surrounding those cities [27]. As we have seen previously, in order for Internet service to be offered through one of these towers, it must be connected to a high-capacity Internet backbone. At the customer premises, a parabolic antenna not unlike a satellite dish is installed on the roof with a line of sight to the nearest tower. Inside, a set-top receiver similar to a digital cable box is hooked up to a Figure 28: MMDS Modem [55]television, providing several digital TV channels. An MMDS modem, similar to a cable modem, can be hooked up to a computer to provide a high-speed, 1.5 Mbps connection to the Internet. The monthly cost of this Internet service is in the same range as cable and DSL, at $38/mo. Hardware is also quite affordable at about $100 for the modem and $200 for the antenna, TV equipment and installation [27]. Because MMDS technology is not standardized and has such a small market, especially in North America, numbers on deployment cost are very hard to come by. Judging by the fact that MMDS has existed in Ontario for almost ten years but has not reached beyond moderately populated areas, it is probable that the deployment cost for an MMDS base station makes it unfeasible for areas with a low population density. The upcoming WiMAX standard is posed to take over at least part of the frequency band used by MMDS [87], so this technology is likely not far away from becoming deprecated.

Local Multipoint Distribution/Communication Service (LMDS or LMCS) is a broadband wireless service that uses licensed microwave frequencies between 26 and 29 GHz. Because of the wide frequency band available, LMDS has an impressive downlink throughput of 1.5 Gbps and an uplink throughput of 200 Mbps [72: 135-136]. This high microwave frequency Figure 29: LMDS Antenna [37]means, however, that range is limited to about 8km, line of sight is required, and rain, fog and snow will interrupt the signal. LMDS can be used as point-to-multipoint (last mile) infrastructure, or as a point-to-point (pipeline) link using parabolic antennas and microwave transmitters. The equipment needed for the 26 to 29 GHz frequency band is difficult to manufacture and is not manufactured in any great quantity, and therefore it is very expensive. A base station costs about $100,000 to deploy while a client station costs about $4,000 [83]. Like MMDS, licensing is also required for this technology, which adds to the deployment cost. The support behind LMDS has been waning in recent years because of greater fibre optic market penetration and the new WiMAX standard. Indeed, the fact that the most recent articles on LMDS were written between 1999 and 2001 should serve as evidence of this technology's lack of manufacturer and market support.

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© Jake Cormier, 2006 [jake (at) stormcloudstudios.com]
Completed as a partial requirement for the degree of Bachelor of Science (specialized)
Department of Computer Science :: Algoma University College :: Sault Ste. Marie, Ontario :: Spring 2006