WiMax Operator's Manual

56 CHAPTER 3 ■ STRATEGIC PLANNING OF SPECTRUM AND SERVICES
Figure 3-4 provides an example of a popular storage network element, the Sanrad Ethernet
storage switch.
Figure 3-4. The Sanrad Ethernet storage switch. Sanrad is a major manufacturer of Ethernetbased
storage network products. (Courtesy of Sanrad)
Entertainment Services
Broadband wireless, at least in the United States, began as a purveyor of entertainment fare,
principally video programming, and at least one broadband wireless commercial service,
Digital Video Broadcast (DVB), is still striving to compete with cable and direct satellite in this
market, though scarcely at all in North America as yet. I wish them luck, but the prior history of
broadband wireless operators in this marketplace is not encouraging.
For the lower microwave operator to attempt to provide the same type of video programming
emanating from the cable networks and satellite broadcasters is generally a mistake.
Even with digital compression, the network will have difficulty supporting even 100 channels
in most instances and is likely to have to content itself with far fewer. Remember, cable operators
have potentially several gigahertz with which to work, of which most systems today utilize
at least 750MHz. The broadband wireless operator is lucky to have 200MHz and is more likely
to have 100MHz or less. If the network operator is committed to the notion of converged
services, which is probably the only business model that will succeed in the long run, then that
100MHz or less must be divided among several other services—basic access, VPNs, LAN extension,
telephony, conferencing, telemetry, and so on—and the decision to do video will leave
little bandwidth for anything else. To date, few subscribers to broadband services have signed
on primarily to get video, and very high bit rate DSL (VDSL), the one new two-way access
technology specifically designed to support video, has enjoyed at best limited success in the
marketplace.
At the same time, VDSL could provide a model for a video service with the potential for
success, one that would avoid the inherent constraints in the old MMDS model.
All broadband wireless video networks to date have resembled cable networks to the
extent that all channels were sent to all viewers simultaneously in just the same manner as traditional
over-the-air UHF and VHF television broadcasts, and, in a strictly one-way network
where the viewer cannot signal back to the studio, that is practically the only way to distribute
the content. But in a two-way network where each user is assigned some portion of the spectrum
for exclusive use, then the viewer need not tune up and down the spectrum at the
premises in order to select a program, and the program itself need not be assigned to any
particular channel. Instead, the tuning function could occur at the base station, and the
selected program would then be sent down a channel assigned to the subscriber rather than
to the program itself.