Number of bars - an explanation

I finally found an explanation why the number of bars doesn't matter
with SPCS - http://tinyurl.com/bemg5.

"Now, with GSM, the signal strength indicator is exactly that, a signal
strength meter. So, the more bars you have, the stronger the signal you
get from the tower is. You can rely on this to evaluate the signal
penetration in a given building.

For CDMA though, it's different. The system is designed so that you can
always add another phone on the tower, "talking" and "listening" on the
frequency, but in the process adding "noise" to all other phones. So
signal strength is not really important. The signal strength on CDMA
cell phones indicates the signal to noise ratio (SNR), in other words,
the signal quality. That means that you can stand in one spot for say,
one hour, and see the indicator on your phone fluctuate between 0 and 4
bars constantly. The quality of the signal depends on how much signal
is getting in the building, but also how many phones are in your
vicinity. The more phones are present, the worse the signal is."

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Junior Samples wrote:
> http://tinyurl.com/bemg5.
> "The signal strength on CDMA
> cell phones indicates the signal to noise ratio (SNR), in other words,
> the signal quality. That means that you can stand in one spot for say,
> one hour, and see the indicator on your phone fluctuate between 0 and 4
> bars constantly. The quality of the signal depends on how much signal
> is getting in the building, but also how many phones are in your
> vicinity. The more phones are present, the worse the signal is."

That's not believable. I live not far from the intersection of two
major highways. A _huge_ amount of traffic goes in both directions
on both highways at all hours. According to this (since some major
fraction of those drivers are Sprint customers), I should see the
bars on my phone going up and down -- going to zero according to
this article -- and I don't. Just four steady bars, since there is
a tower very near that intersection.

BTW, there is a (corporate) Sprint store in a shopping center
right next to that intersection. Steady, four bar reception
when I visit that store.

ll wrote:
> Junior Samples wrote:
>
>>http://tinyurl.com/bemg5.
>>"The signal strength on CDMA
>>cell phones indicates the signal to noise ratio (SNR), in other words,
>>the signal quality. That means that you can stand in one spot for say,
>>one hour, and see the indicator on your phone fluctuate between 0 and 4
>>bars constantly. The quality of the signal depends on how much signal
>>is getting in the building, but also how many phones are in your
>>vicinity. The more phones are present, the worse the signal is."
>
>
> That's not believable.

I guess to someone who is unaware of how CDMA works, that would be a
resonable response. But it is not only believeable, it is correct.

> I live not far from the intersection of two
> major highways. A _huge_ amount of traffic goes in both directions
> on both highways at all hours. According to this (since some major
> fraction of those drivers are Sprint customers), I should see the
> bars on my phone going up and down -- going to zero according to
> this article -- and I don't. Just four steady bars, since there is
> a tower very near that intersection.

You are basing your assumptions on empirical analysis, and not factual
data. You SEE a tower, but are you 100% sure that a. it's a Sprint
tower, and b. it's the ONLY Sprint tower that serves that area? In a
well-deployed region, a CDMA handset will have two or three cell sites
overlapping the same sector, facilitating soft handoff and greatly
improving ec/Io (and ensuring those four bars that you keep seeing).

A major interstate or highway is likely to be well covered, as that is
where Sprint typically focuses its buildout first. In a fringe area,
however, you're likely to see pilot pollution and cell breathing on a
much more visible scale.

Additionally, you are presuming that all Sprint cell phones in the
vicnity are going to be in use. If the phones are not active in calls,
then they do not contribute to pilot pollution. Not everyone likes to
talk while they drive (personally, I WANT my insurance rates to stay
relatively low), so I and a lot of other people I know tend to avoid
yakking on their phones while actively driving unless its absolutely
necessary to do so. The situation might change somewhat if the traffic
was in a gridlock state, and people were anxious to inform others of a
travel delay (I remember that it was nearly impossible to get a call
through on Sprint on Memorial day weekend while stuck on I-95, while on
most other days, coverage is just fine).

> BTW, there is a (corporate) Sprint store in a shopping center
> right next to that intersection. Steady, four bar reception
> when I visit that store.

I wouldn't be surprised if that was another reason for having multiple
cell coverage there. The Sprint store may even have its own microcell
(common practice among coprorate stores for all major carriers).

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