Re: is the LBT catgeory 4 in line with the 5GHz ELAN harmonised standard as of article 3.2 Directive 2014/43/EU?

[Biljana Bojovic]

Hi George, 

in the 5G-LENA NR-U module, the CW adaptation based on HARQ is implemented. The code is here: https://gitlab.com/cttc-lena/nr-u/-/blob/master/model/nr-lbt-access-manager.cc, NrCat4LbtAccessManager class. Also, you can see this paper: http://www.cttc.es/publication/nr-u-and-ieee-802-11-technologies-coexistence-in-unlicensed-mmwave-spectrum-models-and-evaluation/.

Kind, regards,

Biljana

On Wed, Mar 23, 2022 at 11:50 AM George <frangulea...@gmail.com> wrote:

  Hello, 

• I was wondering if someone know if the Listen Before Talk category 4 from ns-3 is in line with the 5GHz harmonised standard. 

I have attached the file with the standard and the flow chart that shows the flow of the LBT cat 4 is shown on page 109 (Annex F) Flowchart for Adaptivity (Initiating Device).

• Also would be very helpful is someone points me at the files where I could see how the LBT procedure works or any useful materials related to the ns-3 procedure. 

Thank you!

Kind regards,

George

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[George]

Hi Dr B. Bojović,

Thank you very much for the materials! I have read this paper in the past before I started to work in ns-3. So now I think this paper will give me more insights. Thank you!

• A question, are the changes such as WiFi (WIGig in the paper) being able to account for interference from other RATs, being integrated into the current modules that are available for the community? If not I guess I will have to start looking into it and find a way to achieve this. I should specify I am trying to build an indoor NR-WiFi at sub 7GHz coexistence scenario. 

Kind regards,

George

[Biljana Bojovic]

Hi George, 

you can find the working example with Wifi 802.11 ax https://gitlab.com/cttc-lena/nr-u/-/blob/master/examples/cttc-nr-wifi-interference.cc. With Wigig, we, unfortunately, don't have any working example, because we were not allowed at that time to share the Wigig code that we used, and now that code is obsolete.

To work with nr-u, you need to download ns-3, nr module, and nr-u module. Currently, you need to use ns-3.35 + nr 1.2 + nr-u 0.2. This is for you to know when you download the code with git clone, to know to check out correct branches. I am saying this because in past all versions of nr worked with almost any release of ns-3. After the release of ns-3.35, we started to notice compatibility issues.

Soon, I hope in the next weeks, will be released ns-3.36, then we will release also nr 2.0. Once this happens, if you decide to move to ns-3.36 + nr 2.0, you will need to test if nr-u can compile correctly with the latest nr, and probably upgrade nr-u to the latest nr (switch nr-u to use CMake instead of the waf build system, and adapt to some changes in nr PHY and MAC due to recent MIMO implementation). If you manage to upgrade nr-u to be compatible with the nr, that would be a great contribution.

Kind regards,

Biljana

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[George]

Hi Dr B. Bojović,

Thank you very much for the details of the proper use of the modules. I am going to use ns-3 for my PhD so hopefully, I will have some good contributions for this community.  

I already have a modified version of the nr-wigig-coexistence code where I implemented the WiFi module used in the nr-wifi-interference. I still have to figure out some things such as (always extremely low SINR at WiFi acquired through the SQL database) so I can make sure I produce accurate measurements and then further build up my study. 

At first, I will be looking at the interplay between Beam-based LBT and latency requirement for URLLC , grant-less scheduling in NR-U, LBT latency and blocking at different offered loads, so hopefully, I will have some good contributions during this journey and give something back to the community!

Thank you for the support!

Kind regards,

George

[Mohammadreza Fasihi]

Hi George,

I am working on coexistence of WiFi and NR-U as my PhD study too. I've implemented a WiFi version of nr-wigig-coexistence code and I have a problem. When I change the "gnbCamType" to "ns3::NrCat4LbtAccessManager" I receive this error:

Simulation Time: +0.001s real time: 21h, 48m, 58s.
Simulation Time: +0.101s real time: 21h, 49m, 1s.
Simulation Time: +0.201s real time: 21h, 49m, 5s.
Simulation Time: +0.301s real time: 21h, 49m, 6s.
Simulation Time: +0.401s real time: 21h, 49m, 7s.
Simulation Time: +0.501s real time: 21h, 49m, 9s.

msg="Cannot TX while RX.", +0.504428568s 14 file=../contrib/nr/model/nr-spectrum-phy.cc, line=566

Did you face this error?

Best,

Mohammadreza

[Patrick Jane]

Hi George,

I would like to express my appreciation for raising the question regarding the simulation challenges concerning the coexistence of WiGig and NR-U. 

You mentioned that you were working on the interplay between Beam-based LBT and latency requirements for URLLC. 

As I am currently conducting research on ns-3 simulations related to Beam-based LBT, I am curious to know if you have made any progress in your project.

If it is convenient for you, could you please share some information about your findings?

Best regards,
Zhongwei

[George]

Hi Zhongwei, 

A stable version of WiGig it is not been released yet for NS3 but you can use various WiFi standards for sub-7 GHz. 

The NR-U module made available from 5G-LENA does support analog beamforming (1-beam transmission at a time). However, even when using beam-based transmission, before a COT is acquired, the sensing involved in the LBT it is done omnidirectional. In order to do LBT sensing through the energy captured by directional means instead of omnidirectional you will need to modify the current implementation. 

I am currently working with omnidirectional - transmission and sensing following to test directional transmission with omnidirectional sensing. 

I think somewhere in September I will start looking into modifying the current LBT so that it allows for directional sensing followed by directional transmission. 

If you do want to do development work that would be much appreciated and we can talk more about that. Also, more details about what you would like top to achieve would be helpful. Should mention beam-based LBT it is standardised now so it must follow the new procedure. 

Kind regards,

George

[Patrick Jane]

Hi George,

Thank you very much for your detailed response. It has helped me gain a better understanding of the implementation details of LBT.

Yes, George, I am indeed interested in contributing to the development work related to beam-based LBT implementation, as it will be relevant to my research.

Regarding my research, it primarily focuses on investigating beam-based LBT and its different variants, including paired-LBT etc., and their impact on the fair coexistence of IAB networks operating in the unlicensed mmWave frequency bands with other RATs.

Furthermore, you mentioned that LBT has been standardized. Are you referring to the 3GPP standards? Could you share more information about this? 

Cause as I know the TR38.889 V16.0.0 (2018-12) has not mentioned any details about the implementation of beam-based LBT. It is the latest technical report version I can find related to the accees procedure  to unlicensed spectrum.

Best regards,
Zhongwei

[George]

I will email you in private so we don't spam the ns3 groups with information not related to the NS3. 

[Patrick Jane]

Hi George，

Thank you for your reply. I look forward to receiving your email and continuing our conversation.

Best,

Zhongwei

[Patrick Jane]

Hi George,

I have developed some beam-based LBT implementation in ns-3, but I have encountered some problems. 

I remembered you said that we can communicate in private so that we don't spam the ns3 group.

So how should I email you so that we can communicate about the beam-based LBT implementation problem?

Best,

Zhongwei

[George Frangulea]

Hi Patrik,

I am away at the moment and I will be back at work sometimes around 1st Sept. 

In the meantime you can describe to me what you did and what final goal you foresee for this implementation and I will have a look. I will email you back in about a week. 

Email:  gv...@Kent.ac.uk

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