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From: chapman@alc.com (Brent Chapman)
Newsgroups: comp.dcom.telecom
Subject: Cellular Phone Signal Propagation Characteristics?
Message-ID: <15746@accuvax.nwu.edu>
Date: 1 Jan 91 23:00:18 GMT
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Organization: Ascent Logic Corporation; San Jose, CA
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X-Telecom-Digest: Volume 11, Issue 3, Message 2 of 5


On a drive from the San Francisco Bay Area to Northern Arizona and
back over the holidays, I was amazed by the extent of cellular service
coverage.  My phone was claiming there was at least intermittent
service almost the whole time I was in California.  The only place in
California where service got spotty was in the desert East and West of
Barstow, along California Highway 58 (between Bakersfield/Mojave
coverage and Barstow coverage) and Interstate 40 (between Barstow
coverage and Needles coverage); even there, though, I would estimate
that the phone showed coverage at least 75% of the time, and "No
Service" only 25% of the time.  I don't have a signal strength display
on my phone, so I'm not certain how good most of the coverage was, but
I successfully placed a few calls from these rather desolate areas,
and the quality didn't seem much worse than what I usually get in the
Bay Area.

What are the propagation characteristics of cellular service?  I was
under the impression that it was tuned to be strictly a short-range
(i.e., less than ten miles) system, and that in fact this short-range
characteristic is fundamental to making the system work (because
shorter range allows smaller cells, and thus more total callers by
reusing the same frequencies in more non-adjacent cells).  How, then,
was I receiving service when I'm sure I was at least 60 miles from the
nearest cell?

On a related topic, I've been told that cell size is not uniform, and
that it is a common practice in densely populated areas (like downtown
San Francisco, for instance) to reduce the power of each cell in order
to reduce the cell size to the absolute minimum and thereby increase
the total capacity of the system.  Is this true?


Thanks!

Brent Chapman                    Ascent Logic Corporation
Computer Operations Manager      180 Rose Orchard Way, Suite 200
chapman@alc.com                  San Jose, CA  95134
                                 Phone:  408/943-0630