The prevailing view seems to be that wide-area wireless
devices need to be "mobile" in the sense that they are
able to move from one network to another. This is not
the case, and maybe not even desirable. I believe that
this view has led to easily avoidable delays in wireless
internet services.
There are a few wireless companies that provide proxied
web and email services over existing cellular telephone
networks. For example, Omnisky, popular with Palm users:
http://www.omnisky.com/images/newCoverageMap.jpg
Those coverage patterns are probably typical, and
suggest that it would be much easier for them to provide
a local gateway in each non-overlapping coverage area
than to implement protocols such as "Mobile IP" which
perform hand-offs from one subnet to another, without
any noticeable degradation in performance.
Of course, this can be taken too far. I've mentioned
that Metricom/Ricochet packets sent from California make
their next IP hop in New Jersey, with 0.75 s latency.
Is there any compelling reason why wireless IP needs to
be "mobile" in the sense of traversing networks?
Cheers,
James
