A look at WiMax, problems and pluses
<http://www.computerworld.com.au/index.php/id;748240611;fp;2;fpid;3>

But the version of WiMax that is capturing everyone's attention is
mobile WiMax. The spec for this technology doesn't yet exist, but it
will be based on the very new IEEE 802.16e-2005 standard. The idea
here is simple: a metro-scale, broadband, all-IP service with full
support for time-bounded traffic like VoIP.

Mobile systems are much tougher to engineer than fixed systems for a
number of reasons. First, while we'd like to keep the number of base
stations to a minimum because they're expensive, the nature of a
given radio connection changes as the mobile end moves. Specifically,
fading comes into play, and at times the signal may fade so much that
a connection can't be maintained.

We may also have problems with capacity as lots of users attempt to
access the relatively limited number of channels available. The
solution here is simple in one respect -- just add more base
stations. Cellular carriers have to deal with this problem on a daily
basis, but, again, the expense involved is one of the reasons that
cellular systems still feature dropped calls, occasional gaps in
service and (often) slow data throughput.

In fact, comparisons with cellular are quite appropriate here, since
the challenges faced by cellular and mobile WiMax are almost
identical. And therein lies the biggest challenge -- can mobile WiMax
really compete with cellular? Cellular-based wireless broadband
services like 1xEV-DO, available from Sprint and Verizon, and HSDPA
(High-Speed Downlink Packet Access), available from Cingular, will
eventually offer multimegabit data services -- exactly the territory
mobile WiMax is targeting. While it's been theorized that the cost of
mobile WiMax base stations will be less than that of corresponding
cellular equipment, the real costs in operating any wireless network
are in spectrum (it's auctioned to the highest bidder), real estate
and customer-related functions like marketing, sales and support.
WiMax won't have any advantage in these.

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Best regards, FAQ FOR CINGULAR WIRELESS:
John Navas <http://en.wikibooks.org/wiki/Cingular_Wireless_FAQ>