Reflections of CVUS
Thanks Bernard,
Tried looking for the information that says what most of us already know, CVUS works fine in driving rain storms, could not locate it.
Although it is possible to get LMDS service to work
under good weather conditions by using reflections
off buildings, it seems that the service deteriorates
under rain conditions. On the other hand, by installing
reflectors, the service is fine.
Also, for tall buildings n Manhattan, LMDS service
can probably best offered by securing roof rights and
installing an antenna on top of the building instead
of using dish antennas in windows.
finally, NY has a much higher density than Denver, so that
even if more cells are needed, the population per cell
will be at least just as large, so the LOS argument does
not explain the high per pop bids for Denver.
I add this to your comments:
Bossard's innovation: The super-high frequency end of the radio
spectrum has never been put to commercial use because its signals tend
to break up in bad weather. The inventor says he eliminated that
problem by using repeaters to strengthen the signal.
Once that difficulty was eliminated, Bossard says the high-frequency
radio waves had several advantages over the lower ranges used for
television, satellite and wireless phone services. The high-frequency
range wasn't overcrowded, so there was enough room to carry huge
amounts of information. "It's like a fiber-optic cable in the sky," says Shant Hovnanian.
High-frequency waves also can be bounced off walls, eliminating the
need for a direct line of sight between the transmitter and receiver,"
Hovnanian says. Bell Atlantic and Nynex canceled their relationship
with CAI Wireless, which used a similar technology known as MMDS,
over that issue.
usatoday.com
Smart move on BA and Nynex part, lets check the Spectrum difference
again:
cellularvision.com
CellularVision signals do not require direct line of sight between
the receive antenna and the transmitter, which is necessary
multipoint distribution systems ("MMDS"). By transmitting using the
FM band, the signal assumes certain characteristics that are unique
to the CellularVision system. CellularVision signals are able to bounce, or reflect off virtually any surface, thus increasing the coverage area and reducing engineering costs. Unlike MMDS technology, interference, multipath and "ghosting" pose no problem and are non-existent with the CellularVision system.
(snip)
he technology is best described as broadband, bi-directional equivalent of a "fiberoptic cable in the air". Cellular Vision is a 'green' product that delivers the entire band width of either 1 GHz or 2GHz to the entire cell using RF power levels that are the equivalent of about 12 watts per television channel. Assuming the delivery of 50 channels, this would mean that the frontier at the center of each cell would use RF power levels of approximately 600 watts. Regular over-the-air television operates at 1,000,000 watts per channel for low band and at 1,000,000 watts per channel for UHF signals.
(snip)
5. Advanced Television (ATV) Current plans in the U.S. call for conventional broadcasters to begin delivering ATV or High Definition Television (HDTV) signals be duplicating their existing transmissions on a second 6 MHz allocation of spectrum in the UHF band. After a fifteen hear period, the original transmissions would cease and the original broadcast spectrum would be reallocated for other uses.
This plan presents a number of challenges for both broadcasters and government departments responsible for spectrum management. Conversion of broadcaster studio and origination equipment will preclude any significant advertiser revenue.
The use by each broadcaster of a dedicated UHF transmitter (that is very expensive both to purchase and operate) to provide a digital, ATV duplicate of the primary signal will magnify these challenges. In Canada/U.S. border areas, where numerous licensees broadcast on both sides of the border, it may be difficult to find sufficient UHF spectrum to serve all existing licensees.
One possible solution to this dilemma would be for the ATV signals of all broadcasting licensees in urban areas to be delivered only via a single CellularVision system. Commercial advertising revenue for broadcasters who choose to offer ATV signals will likely be small to non-existent until a sufficient number of households obtain ATV receivers or display devices.
Offering ATV conversion costs until consumer penetration builds top the point where commercial revenue begins to flow.
"Early adopters" who believe in the added value of ATV programming would undoubtedly pay a premium in the initial phases. However, market forces would eventually drive subscription fees down as broadcasters to entice more people to adopt the ATV technology in order to build the critical mass of households to view clients' ATV commercials. As such, CellularVision would solve the ATV spectrum congestion problem and provide a less expensive transmission alternative and a solution to broadcaster's ATV revenue conundrum.
cellularvision.com
Recent News
Posted: 3:00 p.m. EST, 3/3/98
Millitech, Stanford Telecom win contracts for Denver's LMDS trial
By Loring Wirbel
DENVER -- Millitech Corp. and Stanford Telecommunications Inc. will
provide equipment to establish a local multipoint-distribution service
(LMDS) broadband pilot system here, under contracts from Formus
International Inc.
The contracts will integrate Millitech's 28-GHz broadband wireless local loop hub and transceivers for point-to-multipoint radio, along with wireless ATM equipment from Stanford Telecom (Sunnyvale, Calif.).
Formus has an FCC experimental license to demonstrate a two-way
broadband Internet-access system using LMDS radio. Millitech (South
Deerfield, Mass.) has deployed LMDS and WLL systems in other
countries, but the Formus pilot represents the first significant U.S.
installation. Formus has developed similar millimeter-wave systems in
Poland, New Zealand, and Ecuador.
Regards,
JW@KSC |
