[srsran-users] Implementing V2X sidelink over srsRAN

[Andre Puschmann]

Hey Andrea,

On 9/11/21 0:22, Andrea Lacava wrote:
> I am currently working on a project involving the use of V2X and LTE 
> sidelink.
> I have found the introduction guide on the official documentation 
> (https://docs.srsran.com/en/latest/app_notes/source/cv2x/source/index.html 
> <https://docs.srsran.com/en/latest/app_notes/source/cv2x/source/index.html>) 
> and read the code in lib/examples/pssch_ue.c and I have some questions 
> about it:
> 
>   *
> 
>     In 3GPP TR 21.914 V14.0.0 Section 7, the V2X for LTE is introduced,
>     presenting two different communication interfaces for it: LTE-PC5
>     and LTE-Uu. What interface is used in the example proposed?

The srsRAN C-V2X example implements the PC5 interface, i.e. direct 
communication between two UEs.

> 
>   *
> 
>     In the example proposed it seems that only the physical channel is
>     being taken into account. Is there a way to use the pssch code with
>     the enb code and the ue code?

No. The normal eNB and UE code isn't touched. Also note again that we 
only targeted the PC5 interface, not the Uu part.

But building the upper layers of the UE is not too difficult as 
MAC/RLC/PDCP are only slightly modified for V2X. Also adding a 
third-party ITS-G5 stack, like Vanetza [1], should be quite 
straight-forward.


[1] https://www.vanetza.org/

> 
>   *
> 
>     I have seen the pssch(.h / .c) implementation, but I can not find
>     any API reference or guide in the code nor in the official
>     documentation. Is there another way to understand how these
>     functions work?

No, as always the code is a best documentation.

> 
> 
> My final goal consists in creating an LTE eNB and a UE capable of 
> sending and receiving data using the sidelink using both the 
> communication interfaces reported above. Do you have any suggestions on 
> where to start?

Adding support for Uu is quite a bit of a task as it involves RRC and 
many more layers. But as I explained above, extending the PHY layer 
examples and building demo UE with a third-party ITS stack on top of the 
PHY/MAC/RLC/PDCP is quite doable.


Cheer
Andre

> 
> 
> Thanks for your attention,
> 
> Best Regards
> 
> *
> 
> -----------------------------------------------------
> *Andrea Lacava*
> **Ph.D. student [at] Northeastern University, Boston, MA USA
>          Ph.D. student [at] Sapienza, University of Rome, Italy
>          www dot andrealacava dot com
> 
> 
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-- 
Andre Puschmann

Software Radio Systems (SRS)
https://www.srs.io
andre at srs.io

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