ubuntu-phone team mailing list archive

[Tony Espy <espy@xxxxxxxxxxxxx>]

On 04/22/2015 09:10 AM, sturmflut wrote:
> Hey,
>
> On 22.04.2015 13:35, Michael Zanetti wrote:
> > On 22.04.2015 13:15, Wayne Ward wrote:
> > > Thats a relief its funny how it used to show 2g 3g on the nexus
> > > 5 im probably going to flash it when vivid becomes available
> > > instead of using reset phone option as im sure it resets the
> > > phone but not the mobile sim stuff ?
> >
> > If I understand correctly HSPA is actually better than 3G :) It is
> > 3G with some "High Speed" extensions. Similar as EDGE is "Enhanced
> > Data rates for GSM Evolution", an upgrade to 2G, also referred to
> > as 2.5G.
> >
> > Looking at the specs of the devices, it looks like the Nexus 5 has
> > "only" HSDPA, which would only offer the high speed extensions for
> > the down link, but not for the uplink while the bq claims to
> > support HSPA+, in both directions. That could well be the reason
> > why the indicator shows 3G on one, but H on the other.
> >
> > That said, I'm not a total expert on this field, so take it with a
> > grain of salt, but at least it would match with those:
> >
> > http://www.gsmarena.com/lg_nexus_5-5705.php
> > http://www.bq.com/gb/products/aquaris-e4-5.html
> >
> > https://en.wikipedia.org/wiki/2G
> > https://en.wikipedia.org/wiki/Enhanced_Data_Rates_for_GSM_Evolution
> https://en.wikipedia.org/wiki/3G
> > https://en.wikipedia.org/wiki/High_Speed_Packet_Access
>
>
> I think I can provide some clarification here:
>
> 2G ist standard GSM.
> 2.5G is EDGE, most devices display an "E" for this.
> 3G is UMTS, most devices display a "3G" for this.
> 3.5G is HSPA/HSPA+, most devices display an "H" for this.
> 4G is LTE, most devices display a "4G" for this.
>
>
> To the confusion surrounding 3.5G, or the "H" displayed by most
> devices: It actually consists of two parts, downstream acceleration
> (HSDPA) and upstream acceleration (HSUPA). If a device supports HSPA
> (which both the Nexus 5 and the bq do), then it has to implement both
> HSDPA and HSUPA in at least their minimum specifications of up to 14
> MBit/s downstream and 5.76 MBit/s upstream. There is an extension for
> HSPA called HSPA+, which increases the maximum bitrates, and there
> will likely be even more extensions in the future.
>
> So Michael is absolutely correct, "H" is better than "3G". Usually
> much better.

Simon --

Thanks for the super-clear explanation, it's one the best write-ups I've 
seen that explains all of the possible bearer technologies.

> Now back to the original question: The Nexus 5 actually has the better
> radio part because it also supports LTE, which the bq doesn't. So if
> both devices were tested with the same SIM card in about the same
> location, both should have switched to HSPA and displayed the "H"
> indicator.

As we never *fully* supported the Nexus5, there could multiple 
explantions for why this doesn't work.  Most likley the standard 
translation of RIL constants/messages ( ie. done by the ofono/rilmodem 
driver ) into ofono enums/events has issues when run on the Nexus5. 
This could be a difference in RIL enum values, a difference in RIL 
message semantics, ...

We'd gladly help anyone that wanted to debug this issue and work on a 
fix, but we can't really put cycles into fixing the issue ( if it still 
exists of course ).

Regards,
/tony