A more aggressive strategy than MMDS is a delivery
service called Local Multipoint Distribution Service (LMDS), also known
in Canada as Local Multipoint Communication Service (LMCS). The major
disadvantages of MMDS are the lack of an inband return path and the lack
of sufficient bandwidth to surpass cable channel capacity (by offering
superior interactive data services). A strong Internet access network
must have two-way service and enough bandwidth to compete with data and
cable.
LMDS is a two-way, high-bit-rate, wireless service
under development by a variety of carriers to solve the return-path
problem and vastly increase bandwidth. If significant technological
hurdles can be overcome, LMDS offers the greatest two-way bit rate of
any residential service, wired or wireless, at surprisingly low
infrastructure costs.
No restrictions exist as to how carriers use their
bandwidth, so bandwidth can be subdivided in any manner carriers see
fit. If an LMDS carrier had 1150 MHz of bandwidth, for example, it would
be possible to use 500 MHz for broadcast TV, 50 MHz for local broadcast,
300 MHz for forward data services, and 300 MHz for upstream data. Using
only the relatively robust QPSK modulation, this bandwidth can provide
the following:
- All the broadcast channels of DBS (500 MHz)
- All local over-the-air channels (50 MHz)
- Up to 1 Gb of full-duplex data service (600 MHz)
In other words, the potential exists to offer more TV
than satellite and more data than cable. This frequency plan is just one
example of how a carrier could choose to offer service. Other carriers
might choose to segment their frequencies differently and would be
permitted to do so under FCC rules.
For businesses in cities, LMDS is a very
cost-effective broadband wireless alternative to land-lines for multiple
services. LMDS operates at higher frequencies where more spectrum is
available (bandwidths currently range up to 155 Mbps) and smaller,
cheaper antennas are possible.