[Discuss] cell Network time no longer provided

[mark at buttery.org (Shirley Márquez Dúlcey)]

So far, US carriers are still using legacy protocols (GSM and CDMA)
for voice calls and text messages. Higher speed protocols (HSDPA,
HSPA+) are used for the data side by GSM carriers; CDMA carriers use
EVDO. Both use LTE for their latest data offerings. They are starting
to implement VoLTE (voice over LTE) as a replacement for legacy
protocols but it will be years until the switch is complete.

I don't know whether LTE includes any notion of time services; if not,
the current notion of carrier-provided time will go out the window
when LTE-only devices start to appear. But any LTE-capable device
could easily synchronize to an NTP server on the internet if the OS
includes that capability. So far as I know neither iOS nor Android
currently does, though you can get third party apps to add automatic
NTP synchronization to a rooted Android device.

On Mon, Mar 16, 2015 at 10:36 AM, Kent Borg <kentborg at borg.org> wrote:
> On 03/16/2015 09:46 AM, Shirley M?rquez D?lcey wrote:
>>
>> CDMA networks (Verizon, Sprint, and their MVNOs) are unlikely to make
>> that change because they MUST have accurate time sources available at
>> every cell site.
>
>
> They have to have precise timing to make CDMA soft-hand-off work, but does
> that necessarily translate into providing the civilian time information that
> the phone OS is looking for?
>
> "Time", in a physics sense, is pretty simple. Some cool relatively stuff,
> and questions about why it is unidirectional, not withstanding.
>
> But "time", in a civilian sense is complicated as hell: We want it to line
> up with contradictory celestial stuff and the changing whims of law makers
> on various levels of government and in various geographies.
>
> Providing precise phase information to CDMA isn't the same as knowing when
> daylight saving time begins. Might they have just dumped the civilian part?
> Remember, GPS time is now many seconds off of the seconds-portion of
> civilian time.
>
> Also, aren't the old GSM carriers now using updated protocols that are
> getting all spread spectrum on us? Do they need some of that precise timing
> coordination now, too?
>
> -kb
>
>
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