[srslte-users] Request for information on handoff support in srsLTE

[Soumyadeep Datta]

Hi Francisco,

Thank you so much for your insightful reply. However, I am really new to
this, hence I could not fully understand what you are suggesting.

I am working on the master branch, and as suggested by you, I checked the
code in ./srsue/src/upper/rrc.cc and a header file
./lib/include/srslte/asn1/rrc_asn1.h to see how the
RRCConnectionReconfiguration works in srsLTE. I could not find the exact
parameter in the "meas_cfg" structure where I can add the neighbour cell
index and recover its signal strength.

I shall be highly obliged if you could direct me to the correct file(s) I
may need to look at for this in case I am wrong with that, and the correct
parameters I might need to modify to be able to monitor the signal strength
to both the eNBs (I shall initially attempt to make the setup with 2 eNBs).

Yours sincerely,
Soumyadeep Datta.

On Fri, 21 Jun 2019 at 04:25, Francisco Paisana <
francisco.paisana at softwareradiosystems.com> wrote:

> Our srsUE already supports handover. Its signal strength measurement
> configuration is set by the RRCConnectionReconfiguration message. So, if
> you need to extract neighbour cells' signal strength, you could add the
> cells you need to the measCfg in the eNB
> RRCConnectionReconfiguration message.
>
> Making the actual S1 handover is much more complicated though. If you
> don't really mind extra latencies, you could just force the UE to establish
> a new cell selection and RRC connection once it finds a stronger target
> cell.
>
> Another issue you have to pay attention to is having the source and target
> cells well aligned in frequency. The way UEs perform signal strength
> measurement of neighbour cells assumes good inter-cell frequency
> synchronization. This can be achieved with an external clock reference
> (e.g. ettus octoclock).
>
> Regards,
> Francisco
>
> On Thu, Jun 20, 2019 at 4:43 PM Soumyadeep Datta <dsoumyadeep97 at gmail.com>
> wrote:
>
>> Hi Francisco,
>>
>> Thank you for your reply.
>>
>> I need to implement handoff dynamically, for example, in a mobility
>> situation where a UE moves from one BS's coverage region to another.
>>
>> To be able to do that in real time, I need a way to retrieve the received
>> signal strength or some other parameter which will help me decide in favour
>> of one BS over the other and thereafter implement the handoff.
>>
>> Yours sincerely,
>> Soumyadeep Datta.
>>
>>
>> On Thu 20 Jun, 2019, 5:00 AM Francisco Paisana, <
>> francisco.paisana at softwareradiosystems.com> wrote:
>>
>>> Hey Soumyadeep,
>>>
>>> Our eNB does not yet support S1 handover. Regarding your second
>>> question, do you want to set the UE's cell dynamically or just at startup?
>>>
>>> Regards,
>>> Francisco
>>>
>>> On Thu, Jun 20, 2019 at 9:04 AM Soumyadeep Datta <
>>> dsoumyadeep97 at gmail.com> wrote:
>>>
>>>> Hello,
>>>>
>>>> I am a new user of srsLTE platform. I wanted to know if the srsLTE
>>>> stack has support for handoff/mobility in the ePC/Core network. If not, is
>>>> there a provision to manually control the eNB to which the UE attaches? (I
>>>> was considering retrieving some suitable parameter, for instance, received
>>>> signal strength, to achieve this.)
>>>>
>>>> Yours sincerely,
>>>> Soumyadeep Datta
>>>> Final year Dual Degree student,
>>>> Department of Electrical Engineering,
>>>> IIT Kanpur.
>>>> _______________________________________________
>>>> srslte-users mailing list
>>>> srslte-users at lists.softwareradiosystems.com
>>>> http://www.softwareradiosystems.com/mailman/listinfo/srslte-users
>>>>
>>>
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