handoff / handover indicator

[Tomcsanyi, Domonkos]

Hi Ravid,

Not that I know of, no. Sorry.
Without libqmi by directly getting radio traces from the diag port of the modem you could probably observe it, however you must check its contents, because this message is used for a lot of purposes, not only handover. Tools for extracting radio traces include diag-parser, scat, qcsuper (all on github).

Cheers,
Domi

Az iPhone-omról küldve

> 31.08.2021 dátummal, 7:29 időpontban Ravid Cohen <ravidc at ottopia.tech> írta:
> 
> 
> Hi Domi
> 
> Is there a way to get an indication when a RRC Connection Reconfiguration is received using libqmi?
> 
> Best regards,
> Ravid
> 
>> On Mon, Aug 30, 2021 at 11:05 AM Ravid Cohen <ravidc at ottopia.tech> wrote:
>> Hi Domi
>> 
>> Thank you for the clarification.
>> 
>> Best regards,
>> Ravid
>> 
>>> On Sun, Aug 29, 2021 at 8:51 PM Tomcsanyi, Domonkos <domi at tomcsanyi.net> wrote:
>>> Hi Ravid,
>>> 
>>> Correct, the network continously receives measurement reports from the modem, and then in case the threshold is below a certain signal-noise-ratio or similar KPI then the basesatation instructs the modem to change. This is usually where some “magic” could happen, vendors could introduce custom KPIs that will affect if and how a handover will happen.
>>> 
>>> To be more concrete in a specific scenario let’s take LTE. There the actual handover happens by using the RRC Connection Reconfiguration message. Beforehand the source eNodeB aligns the handover with the target eNodeB (e.g. sharing required security keys, checking if even the target eNodeB would be able to accept this new user etc.) then after the ACK from the other side it sends the Reconfiguration. In the background the UE’s user plane (data) tunnels between the eNodeB and the core network are switched as well to the new eNodeB.
>>> In case you have access to the Qualcomm diag port of your modem that could be made to stream out the over-the-air signaling messages to a client program then you could potentially observe this happen, however there is usually no way to easily know before it happens that it is about to happen. Not all thresholds are advertised by the network, in fact most of them are in the eNodeB’s configuration only.
>>> However, if you are just willing to see if there was a handover lately maybe you could query the current cell ID from the modem and see if it changes. If you were doing a data transmission and during it the cell ID changed you could be quite sure there was a handover imho.
>>> 
>>> Cheers,
>>> Domi
>>> 
>>>> 29.08.2021 dátummal, 19:22 időpontban Ravid Cohen <ravidc at ottopia.tech> írta:
>>>> 
>>>> 
>>>> Hi Domi,
>>>> 
>>>> Thank you for the quick and detailed response.
>>>> I'm interested in the first scenario you described (ongoing service, espaclly data).
>>>> 
>>>> If I understand you correctly, the change is triggered by the network provider but the actual switch is made by the modem itself (according to the operator instructions)?
>>>> If that is the case, maybe there's a way to catch this event/s?
>>>> 
>>>> Thanks you again,
>>>> Ravid
>>>> 
>>>> 
>>>>> On Sun, Aug 29, 2021 at 8:08 PM Tomcsanyi, Domonkos <domi at tomcsanyi.net> wrote:
>>>>> Hi Ravid,
>>>>> 
>>>>> Firstly I think the most important is to get the terms correctly: so by handover do you mean handing over an ongoing service (voice or data) from one cell to another, or do you mean cell reselection in idle mode because of moving or change of radio conditions?
>>>>> 
>>>>> The first one is actively triggered by the network to maintain continuity in the service as much as possible, the other happens autonomously by the baseband. Sadly both of them are quite hard to detect, because even though certain events are fired and thresholds are crossed these remain internal to the baseband firmware as far as I know.
>>>>> 
>>>>> Kind regards,
>>>>> Domi
>>>>> 
>>>>> > 29.08.2021 dátummal, 16:30 időpontban Ravid Cohen <ravidc at ottopia.tech> írta:
>>>>> > 
>>>>> > 
>>>>> > Hey
>>>>> > 
>>>>> > I'm not sure this is the right place for such questions, if not please refer me to the right place.
>>>>> > 
>>>>> > I'm using a Sierra modem (em7565).
>>>>> > Is there a way to get notification before the handover process between two cells begins? 
>>>>> > 
>>>>> > Best regards,
>>>>> > Ravid
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