iPhone 4S unable to turn off 3G?!

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.

boocy wrote:

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.

And 5.1 should provide that switch. On the other hand, I was reading recently that 2G will probably be phased out by ATT due to limited spectrum in favor of 4G services. I guess that will leave some people with a choice of upgrading to 3G, or being without service in large areas of the country where 2G is currently the only level of data and voice service.

I wasn't trying to insult your intelligence so please, don't insult mine. I was simply attempting to politely point out that your technical regurgitation is off subject and irrelevant and therefore does not contribute to the discussion in any manner that is helpful.

I thought that it was very relevant and I thank him for taking the time to lay it out in English that even I could understand.

The original conversation died after five folks said I want this and five others pointed out that it was likely in the future as the beta being tested included it. Everything else is superfluous frosting.

Well, I just updated my 4S to 5.1, and if there is a 2G toggle, I didn't find it. Not mentioned in release notes.

Sigh.

I got involved in this thread right at the start and I'm glad to say that it is back for me. iOS 5.1 iPhone 4S 32GB O2 network in UK. Woop!