| Thomas T. Veldhouse 2006-05-19, 5:48 pm |
| In alt.cellular.sprintpcs John Navas < spamfilter0@navasgro
up.com> wrote:
>
> I think it's more a case of being realistic.
>
Reading your comments below ... you are clearly the real Thomas and I am an
imposter ... I do not hold the doubt and cynacism so close to my heart.
>
> Bias is hard to avoid even when there isn't a vested interest in the outcome.
>
You have aggressively post editted my quote and removed all references to the
fact that I am talking about Verizon here. Verizon is doing QC work with
those mobile vans. The data has its marketting uses obviously, and they are
using it. They do not hide the fact that they are the company gathering the
information. As an informed consumer, I am surprised you take such a negative
opinion of it.
>
> My own experience is that very few companies are that objective.
>
It is their own QC data ... there is no point in doing QC work if you don't do
it objectively.
>
> Looks like a big budget ad campaign to me, which pretty much eviscerates the
> case for objectivity.
Cynic. Cynic ... cynic!
>
>
> That's the only safe assumption that can be made.
>
Cynic! Why don't you try and find out if you want to know?
>
> All too many don't.
Again, that is not a problem with the statistics, that is a problem with the
people reading them. Period. It is NOT a problem with the company quoting
them.
>
> That only applies to CDMA -- TDMA (which includes GSM) uses dedicated time
> slots.
>
Of course they have dedicated time slots (that is what T stands for in TDMA
.... GSM just has more of them and they number of slots varies during a call).
The only way to overlap TDMA/GSM zones are to put them on different bands.
CDMA does not have to worry about it. The interference caused by overlapping
GSM/TDMA is absolute, so deployment is much more problematic.
>
> CDMA also requires hand-offs, just differently.
A phone can talk with two or three towers at the same time ... where one tower
is dominant. Then, as the phone moves, tower dominance moves and eventually
one tower ceases to communicate with the phone, at some point another tower is
reached ... and the phone begins talking with it as well ... until the whole
cycle starts again .. there is no *direct* handoff per se ... unless one were
to cross a carrier boundry (not sure if that is even supported these days).
>
>
> As I wrote, the difference (as measured in Erlangs) is relatively small. From
> one of my past posts:
>
<snip<snip<snip<snip<snip<snip<snip<snip<snip>
I challenge you to get real statistics on the call density of urban towers
using CDMA. I have seen it widely reported that CDMA towers are getting
higher call density. Verizon is known to limit the number of calls to a cap
to avoid the severe call degradation that the snipped text mentions. At times
though, it is better to make the call with a little lower voice quality than
it is to not be able to make the call at all. Think about the performance of
phones in Manhattan on 9/11.
> Some time ago, Chris Pearson, Executive Vice President, 3G Americas, wrote:
>
> Many CDMA operators are currently in the midst of deploying 1XRTT, AN
> INTERIM STEP TOWARDS 3G that promises to use spectrum more
> efficiently. Time will tell whether that is the truth but the fact is
> that, based on best-case data from CDMA vendors, 1XRTT with EVRC
> handles up to 156 Erlangs per sector. Bearing in mind that GSM with
> AMR handles 142 Erlangs, it is a great stretch to argue that 1XRTT
> has a major advantage over GSM. GSM operators also can deploy dynamic
> frequency and channel allocation (DFCA), which assigns calls to
> channels based on conditions such as signal and interference. With
> AMR and DFCA, GSM can handle 170 Erlangs per sector - an improvement
> on 1XRTT?s 156. [emphasis added]
>
1xRtt has been out for many years now. Now, what are the field results ...
today, not at the time of that old text.
> In the near future, 1XRTT operators will probably be able to deploy a
> technology called selective mode vocoder (SMV), which could provide
> 20% more capacity over EVRC. The catch is that SMV-like methods can
> be applied to GSM to produce almost identical capacity gains. Thus,
> while one technology may have slightly higher capacity gains at one
> point in time, another technology is always preparing to leap-frog
> over it.
>
Indeed ... so what are the real world results again?
>
> Time slots.
Pardon me ... that is what I am referring too. Actually, CDMA allocates
channels, but it can be several thousand in a minute where CDMA spreads its
packets accross the entire available spectrum allocated at a given location.
>
>
> CDMA is actually quite different from IP packets, which is why cell
> "breathing" is an issue.
I understand perfectly why breathing occurs. The analogy is best described as
noise ... as SNR drops the cell shrinks. The only way to make a call in this
case is to increase signal (power) or to get closer (effectively increasing
power). The IP packets I refer to have nothing to do with breathing. Voice
is broken up into small "packets" and then the phone looks for an available
channel and sends the "packet". The "breathing" you refer to is a result of
spread spectrum and not the protocol directly. The protocol is only relavent
in the fact that is is capable of working in a spread spectrum scenario ... it
should be possible for the protocol to work fine over a different air
interface, such as the timeslots used with GSM and TDMA.
>
>
> Essentially correct.
>
>
> Again, time slots.
Agreed.
>
>
> That's not the actual difference, but again, the difference in capacity is
> relatively small, and irrelevant to subscribers.
Actually, it is the difference. The "packet" of data sent in CDMA is smaller
than that in GSM, thus, one can approach the theoretical limit more closely.
>
> Sure, but the CDMA connection can be horribly unusable, making the difference
> moot. (I speak from considerable personal experience. Since network busy
> isn't a significant problem, I'd personally rather have dedicated time slot,
> but as always, YMMV.)
>
Yes, but the horribly unusable really occurs after the same situation applied
to GSM would result in no call at all. My point is that CDMA can get higher
capacity.
>
> See above for the first part. The second part is patently clear.
Again, what you posted is several years old. Still, having said that I would
like to see real world statistics as to real capacities at real sites. I have
read over and over that CDMA has been offering better capacity, which is major
(but not only) reason why Vodofone(?) has not forced Verizon to convert to GSM
like the rest of its companies use.
>
>
> Doesn't work that way -- roaming is only permitted in areas where there is no
> native network coverage, not as a matter of capacity in native coverage areas.
>
Sure it does. If you ask a user, are you happy and that user answers yes,
then they are doing something correctly. If they are doing it by making an
agreement with local provider XYZ to offer seamless coverage ... then it is
effective.
>
> [shrug]
>
Shrug if you like. GSM doesn't mean SIM. GSM CAN be implemented without SIMs
and CDMA CAN be implemented with SIMs. They are independent technologies that
are traditionally used together.
>
> Cingular is doing well by any reasonable measure.
>
>
> Nonsense. You only discredit your own argument by claiming that facts
> contrary to your point of view much be biased. 'Those who have evidence will
> present their evidence, whereas those who do not have evidence will attack the
> man.' Not only that, but arguments over which is the "best" technology are
> pretty pointless from a subscriber point of view. All that matters is what
> works, and both technologies work quite well.
>
Hehe ... I will leave that to the audience .. but I have watched you respond
here over the last couple of days, to me and to others, and it is nearly
always in support of Cingular in an argument against them ... except perhaps
for their claim of the lowest number of dropped calls.
--
Thomas T. Veldhouse
Key Fingerprint: 2DB9 813F F510 82C2 E1AE 34D0 D69D 1EDC D5EC AED1
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