[srsran-users] [EXTERNAL] Re: eMBMS throughput limit?

Wed Sep 7 22:45:10 UTC 2022

Hey Ron,

I can see from the confs that you are using an older version of SRSRAN, so
the first thing I would do is get the latest version of the code.

The parameters you are referencing here are PDSCH and PUSCH which are
unicast channels, there is another parameter to set the MCS of MBMS which
was added a few years ago, it is not present in the code you are running at
the moment and is fixed to MCS=10 which is why you see this low throughput
for MBMS.

If you grab the latest code you will be able to set a higher MCS for
MBMS in the config file!
Hope this helps!

Regards,
Justin

Justin Tallon

Engineering Manager

Software Radio Systems
justin at srs.io
www.srs.io
Barcelona, Spain
[image: twitter] <https://twitter.com/srssystems>
[image: linkedin] <https://www.linkedin.com/in/justin-tallon-71807136/>

On Tue, Sep 6, 2022 at 11:27 PM Sackman (US), Ronald W <
ronald.w.sackman at boeing.com> wrote:

> Hi Justin,
>
>
>
> Thank you for the reply, this is helpful.  I am using the iperf client and
> server commands exactly
>
> as shown on this link:
>
> https://docs.srsran.com/en/latest/app_notes/source/embms/source/index.html
>
>
>
> Regarding setting the MCS limit, I see the following in enb.conf:
>
> #pdsch_max_mcs    = -1
>
> #pusch_mcs        = -1
>
> pusch_max_mcs    = 16
>
>
>
> Using the ENB console, I verified that the uplink MCS tops out at 16.  The
> downlink MCS appears to
>
> top out at 27.8.  Should I uncomment pdsch_max_mcs and set it to 24?
>
>
>
> From your note, it sounds like the best course of action on my end would
> be to upgrade to Ubuntu 20.04
>
> and retest for a higher value of p_nrb.  Does this sound reasonable?
>
>
>
> Ron
>
>
>
> *From:* Justin Tallon <justin.tallon at srs.io>
> *Sent:* Tuesday, September 6, 2022 7:08 AM
> *To:* J Giovatto <jgiovatto at adjacentlink.com>; Sackman (US), Ronald W <
> ronald.w.sackman at boeing.com>
> *Cc:* srsran-users at lists.srsran.com
> *Subject:* [EXTERNAL] Re: [srsran-users] eMBMS throughput limit?
>
>
>
> EXT email: be mindful of links/attachments.
>
>
>
>
> Hey Joe & Ron,
>
>
>
> Apologies for the delayed response, I have just now seen your emails.
>
> With the default configuration, you should be able to get 11MS/s over the
> MBMS. This is using  PRB=50 and embms.mcs=20, as well as the maximum
> assignment of subframes (6/10).
>
> If you increase the MCS=24(maximum allowable for eMBMS, due to the greater
> number of REs dedicated to reference signals) and set PRB=50, you should
> get 16MS/s.
>
> I have tested this using ZMQ on Ubuntu 21.04. I have noticed an issue with
> 100prbs, not the crashing as you described but some PHY layer KOs, I will
> investigate this and have a fix for the next release.
>
>
>
> Ron, can you share the iperf command you are using? It's possible you are
> flooding the buffers in the RLC which can throw off the eMBMS scheduler,
> causing a drop in performance.
>
>
>
> Joe, I will investigate the issue you have created and get back to you.
>
>
>
> Thanks!
>
> Justin
>
>
> Justin Tallon
>
> Engineering Manager
>
> Software Radio Systems
>
> [image: Image removed by sender.]
>
> justin at srs.io
>
> [image: Image removed by sender.]
>
> www.srs.io
>
> [image: Image removed by sender.]
>
> Barcelona, Spain
>
> [image: Image removed by sender.]
>
> [image: Image removed by sender. twitter] <https://twitter.com/srssystems>
>
> [image: Image removed by sender. linkedin]
> <https://www.linkedin.com/in/justin-tallon-71807136/>
>
>
>
>
>
> On Thu, Jul 28, 2022 at 4:16 PM J Giovatto <jgiovatto at adjacentlink.com>
> wrote:
>
> Hi Ron,
>
>
>
> This question probably belongs on the srsRAN-emane page but with that
> being said maybe the kind folks from srs can chime in and
>
>
>
> report back any thruput testing they may have done with multicast.
>
>
>
> One thing you might want to try is the zmg rf and see if you get different
> results vs emane to help determine if this is an srs or emane porblem.
>
>
>
> Also note there is an issue related to multicast here:
> https://github.com/srsran/srsRAN/issues/936
>
>
>
> Lastly your versions are looking out of date, we are on 21.10 and only
> supporting Ubuntu 20.04 so any testing will not be a true apples to apples.
>
>
>
> Joe
>
>
>
>
>
> On 7/27/22 19:25, Sackman (US), Ronald W wrote:
>
> Hello,
>
>
>
> I am running SRSRAN version 19.9.0 in EMANE, running on Ubuntu 18.04.  I
> followed the
>
> instructions in the user manual section 5.12 “eMBMS End-to-end” and (with
> a few modifications)
>
> was able to get it working.  Testing with iperf or MGEN, I am finding that
> the multicast throughput
>
> is limited to 6Mbps, with an additional 6Mbps of throughput allowed for
> unicast.  If I
>
> attempt to increase throughput by increasing the enb.conf/p_nrb parameter
> above
>
> 25 (e.g. to 50 or 100), the receiving srsue interface crashes as soon as
> it receives the
>
> first packet.
>
>
>
> Using the following calculator with SRSRAN MCS=26.5 (256QAM), n_prb=25,
> and 1X1 SiSo, I am
>
> expecting a total of 24.48Mbps downlink bandwidth, out of which I assume
> multicast would
>
> consume some carve out without reducing the total cell bandwidth.
> However, the cell maxes
>
> out at 6Mbps multicast + 6Mbps unicast.
>
> https://www.cellmapper.net/4G-speed
>
>
>
> Is this the expected throughput performance?  Am I missing a step to
> achieve the calculated
>
> throughput for the cell?  I have attached the ENB and UE config files.
>
>
>
> Thank you,
>
> Ron
>
>
>
> =======================================
> Ron Sackman
>
> Technical Fellow
> Principal Network Security Architect
> Boeing Autonomous Systems / Critical Systems Security
>
> Mountain View CA
> Office: 650-316-3749 Cell: 408-930-7358
> ronald.w.sackman at boeing.com
>
> *Psalm 19:1*
>
>
>
>
>
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>
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>
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>
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