[srslte-users] S1 handover

[Francisco Paisana]

Hey,

I would suggest following the configuration indication in the docs and skip
the parts relative to zmq. I would also suggest to start with the simplest
setup possible (e.g. intra-frequency and intra-enb handover) and complicate
the setup gradually. I would highlight the following considerations for
each type of handover:
- intra-enb handover - avoids any synchronization issues across eNBs (no
GPS or external reference needed) and any complications associated with the
configuration of the MME. You can use srsEPC and srsUE for this, and
leverage the logging and pcap of these two applications.
- S1 Handover - you will need an MME that supports S1 Handover like
Open5GS. You will need to add the target cells for the UE to measure in the
rr.conf. You can try to get it working without a GPS or common reference,
but no guarantees. Last time I checked, the COTS UE worked better than the
srsUE in this scenario without sycnhronization.
- intra-frequency handover - this simplifies the RRC measurement
configuration, and you can use srsUE without any problems.
- inter-frequency handover - to use the srsUE, you will have to activate
Carrier Aggregation in both srsENB and srsUE at the moment. If you don't
want CA, you will have to rely only on COTS UEs and set a measurement gap
period in the rr.conf to activate out-of-band measurements of neighbour
cells.

Let me know if you run into problems.

Regards,
Francisco

On Sun, Jun 13, 2021 at 9:13 PM Philipp Schach <s0564590 at htw-berlin.de>
wrote:

> Hey,
>
> I would also like to try an S1 handover. My setup includes two PCs and two
> B210. PC1 is EPC (Open5GS) and eNodeB (srsRAN) with one B210. The second PC
> is my 2nd eNodeB with 2nd B210. As COTS UE I use a Nexus 5x. The setup is
> currently working now, but without handover. Has anyone tried this setup
> before? Are there any specific things to consider here? Or can I follow the
> instructions in docs for S1 Handover? I will see if I can find a GPS for
> synchronization.
>
> Regards,
> Philipp
>
> Am 10.06.2021 um 13:57 schrieb Francisco Paisana <francisco at srs.io>:
>
> Hey,
>
> Using the same clock source for both eNBs is helpful to avoid that any
> frequency offset affects the UE cell measurements. This is the sort of
> synchronization that is hard to achieve via network signaling. So, I would
> definitely suggest using a GPS or external device as a reference.
>
> I never experimented with handover between B210 and LimeSDR, so I would be
> interested in hearing about your results. At the moment, I don't see any
> reason why it wouldn't work.
>
> Regards,
> Francisco
>
> On Wed, Jun 9, 2021 at 8:23 PM Modyngs <mobilebackup95 at gmail.com> wrote:
>
>> Thanks for the replay
>>
>> Can we also use B210 as master eNB and limesdr as slave eNB to do s1
>> handover?
>>
>> Also I think they should be sync to each other! If yes do we need some
>> GPS signal or some external device to be placed in order to Handover
>> between two eNBs while using COTS UE, or they will sync using EPC signals?
>>
>>
>> P.S : I'm gonna use 3 PCs. One for EPC, one for master eNB using B210 and
>> the other slave eNB using limesdr. COTS would be a samsung S series!
>>
>> Is this setup theoretically work?
>>
>> Thanks
>> Best regards
>>
>> On Wed, 9 Jun 2021, 01:07 Francisco Paisana, <francisco at srs.io> wrote:
>>
>>> Hey,
>>>
>>> The S1 and intra-eNB handover should work with COTS UEs. For the S1
>>> Handover, you will need two RF front-ends to run as source and target enbs.
>>> We support both intra-frequency and inter-frequency handover. For the
>>> latter, you will have to set up the measurement gap period in the rr.conf
>>> file.
>>>
>>> Regards,
>>> Francisco
>>>
>>> On Tue, Jun 8, 2021 at 8:21 PM Modyngs <mobilebackup95 at gmail.com> wrote:
>>>
>>>>
>>>>
>>>> Hi, I was reading the Handover application Note of SRS docs.
>>>>
>>>> Saw that the S1 Handover needs ZMQ( GRC Broker) to manage the gain and
>>>> Handover procedure
>>>>
>>>>
>>>> But is it possible not to use the ZMQ when you are testing with COTS UE?
>>>>
>>>> I can confirm that the procedure works with srsUE and GRC together, So
>>>> can we just omit the srsUE & GRC and replace them with real UE and test the
>>>> S1 Handover without the GRC BROKER?
>>>>
>>>> Thanks
>>>> _______________________________________________
>>>> srslte-users mailing list
>>>> srslte-users at lists.softwareradiosystems.com
>>>> https://lists.softwareradiosystems.com/mailman/listinfo/srslte-users
>>>>
>>> _______________________________________________
> srslte-users mailing list
> srslte-users at lists.softwareradiosystems.com
> https://lists.softwareradiosystems.com/mailman/listinfo/srslte-users
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.srsran.com/pipermail/srsran-users/attachments/20210614/43c89a61/attachment.htm>