Q: iPhone 4S unable to turn off 3G?!

There, there... All is forgiven

Wow this topic has really taken off since I was last on here....  Here I am eagerly, but patiently awaiting the next update to come and this whole thread is doing cirle after circle.....  Do people not read the stuff that is already written in here without people like Allan Sampson and others having to repeat themselves like every 2 posts....  :-)

I was a little confused in the begining, but I understand alot more now.  Allan and the others that have had to actually say stuff multiple times, great work.  I would have gotten frustrated explaining things by about the 3rd time.  

Thank you for all guys who contributed to the discussion!  All we have to do is waiting for the next patch to fix the settings.

As I allready said in 5.1 beta 3 the 2g/3g switch is again implemented, tested and worked fine. So I think in the 5.1 final version the switch will be there. So, yes, we have to wait for the final release of the 5.1 software and to hope the switch will be there. Good day to you all!

laurentiufrompitesti wrote:

 

As I allready said in 5.1 beta 3 the 2g/3g switch is again implemented, tested and worked fine. So I think in the 5.1 final version the switch will be there. So, yes, we have to wait for the final release of the 5.1 software and to hope the switch will be there. Good day to you all!

I hope, that, in addition to returning the switch, they also make the switching to 2G a bit more 'sticky'.  The technical term is hysteresis.  It means that if it switches, it will remain switched for a time before checking again, and not try to change during  a call.

They can't add any hysteresis of their own choosing actually.

As I was explaining way back when this galactic topic began, the network is responsible for all such configuration. The phone dutifully follows protocol.

For idle mode reselection (change serving cell while idle), the phone actively does this based on the thresholds indicated in the broadcast information of the current serving cell.

For dedicated mode handover (while in a call), the phone can only send measurement reports for the set of cells that the current cell tells it to measure, and the network decides when to trigger a handover.

The only way the phone could influence the decision is by lying about its measurements to the network. This would represent a non-conformance to the 3GPP specifications.

if you question my expertise, I will tell you that I have 12 years of experience in this exact area. My world has been DSP coding for equalisers, channel coders and also radio resource management for GSM and UMTS. So I would say that I know more than a little of the subject!!!

What the HE$%^^ is wrong with people who cant understand that 2G is available via 5.1 beta and/or SBSettings......why do people keep disputing the availability of 2G on this chip????!!!!!

And what is wrong with people who don't bother to read what someone has written to understand the point that they are making before making a snap judgement and replying with a a denal of a point that was never actually made?

I NEVER SAID ANYTHING ABOUT 2G NOT BEING POSSIBLE, I WAS JUST RESPONDING TO RPHUNTE42'S POINT ABOUT HYSTERESIS. UNDERSTAND NOW MORON?

jameswbuk wrote:

 

They can't add any hysteresis of their own choosing actually.

 

As I was explaining way back when this galactic topic began, the network is responsible for all such configuration. The phone dutifully follows protocol.

 

For idle mode reselection (change serving cell while idle), the phone actively does this based on the thresholds indicated in the broadcast information of the current serving cell.

 

For dedicated mode handover (while in a call), the phone can only send measurement reports for the set of cells that the current cell tells it to measure, and the network decides when to trigger a handover.

 

The only way the phone could influence the decision is by lying about its measurements to the network. This would represent a non-conformance to the 3GPP specifications.

 

if you question my expertise, I will tell you that I have 12 years of experience in this exact area. My world has been DSP coding for equalisers, channel coders and also radio resource management for GSM and UMTS. So I would say that I know more than a little of the subject!!!

Thanks for the information.  I guess there is not much Apple can do about this issue, then, except turn off 3G to force 2G mode.  Seems to me that the control is on the wrong end, since the phone is better able to evaluate the signal it sees than the cell, but they didn't ask me.  I appreciate the more detailed information.

The control needs to be defined by the network, as they need to define their cell planning - with regard to traffic shaping etc. The phone has no idea of this detail.

Cellular standards are in place so that we have a fairly defined behaviour that all brands of mobile device conform to. Imagine the chaos if they all made decisions differently (because they think they know better) - and how you would go about inter-operability testing across multiple basestation manufacturers / multiple handset manufacturers...

The phone definitely cannot decide on it's own that it wants to handover it's call to cell X, as that cell might be at full capacity, or being cleared of traffic for some reason,..... It can only report what it measures to the network and let the network decide where to send it.

Basically the network owns the 'radio resource', and is the manager of this resource. It decides who goes where (within the scope of the mobile device's reported device capabilities).

jameswbuk wrote:

 

The control needs to be defined by the network, as they need to define their cell planning - with regard to traffic shaping etc. The phone has no idea of this detail.

 

Cellular standards are in place so that we have a fairly defined behaviour that all brands of mobile device conform to. Imagine the chaos if they all made decisions differently (because they think they know better) - and how you would go about inter-operability testing across multiple basestation manufacturers / multiple handset manufacturers...

 

The phone definitely cannot decide on it's own that it wants to handover it's call to cell X, as that cell might be at full capacity, or being cleared of traffic for some reason,..... It can only report what it measures to the network and let the network decide where to send it.

 

Basically the network owns the 'radio resource', and is the manager of this resource. It decides who goes where (within the scope of the mobile device's reported device capabilities).

I guess that is why, even though there are closer tower to me, I sometimes get a lousy signal.  Seems like the network is run from the top down, rather than the bottom up.  Still, I am sure it isn't likely to change.  I understand that load balancing isn't something the phone can manage.

Plus you have to imagine how it could even work for a phone to decide when/where to handover to...

The target cell may have available timeslots (GSM example), but understand that there are lots of call setups, handovers etc happening all of the time. A phone can't decide to take a slot without the arbitration that is done by a central controller (the network radio resource manager). There would be collisions.

Also a cell usually has many carriers (multiple frequency channels - each with 8 timeslots), and the phone has no knowledge of these.

The only entity in possession of all the knowledge, and is able to command the phone to move to a specified target frequency/timeslot is the network.

There are actually even more reasons that this. There are sub-timeslots for half rate, and even orthogonal channel timeslot sharing where received power at the basestation needs to be carefully balanced between two mobiles. All of this stuff can only be managed by a central entity.

In UMTS, there is also a very careful power balance that happens between all mobiles that are on a particular frequency. I could go on! The complexity is endless!

All we want is to have the ability to switch between 2G or 3G ourselves rather than relying on the mobile to make a poor decision.

We know it is possible to do because previous iPhone versions have that ability and apparently those who have jailbroken phones have that ability with the 4S.

With respect to your years of experince with radio resource management, talk of the phone having the ability to decide which cell tower to use, traffic shaping, networks managing radio resource and so on - is really outside the scope of this discussion.

I am just trying to educate those who are interested in how the technology actually works. Sorry if you prefer to live in ignorance - just don't read it if your brain can't keep up.

The topic has on many occasions made reference to how people think the phone 'should' behave... I am just telling everyone what is possible.

jameswbuk wrote:

 

Plus you have to imagine how it could even work for a phone to decide when/where to handover to...

 

The target cell may have available timeslots (GSM example), but understand that there are lots of call setups, handovers etc happening all of the time. A phone can't decide to take a slot without the arbitration that is done by a central controller (the network radio resource manager). There would be collisions.

 

Also a cell usually has many carriers (multiple frequency channels - each with 8 timeslots), and the phone has no knowledge of these.

 

The only entity in possession of all the knowledge, and is able to command the phone to move to a specified target frequency/timeslot is the network.

 

There are actually even more reasons that this. There are sub-timeslots for half rate, and even orthogonal channel timeslot sharing where received power at the basestation needs to be carefully balanced between two mobiles. All of this stuff can only be managed by a central entity.

 

In UMTS, there is also a very careful power balance that happens between all mobiles that are on a particular frequency. I could go on! The complexity is endless!

Sound so complex it's a wonder it works at all.  And people complain if they get a call dropped....  More education always improves understanding.

Thanks for elaborating.