RAN550 device configuration

[irrenhaus]

Hello,

since the communication with the RAN550 now seems to work on our side I'd like to ask if there is a possibility to get the configuration / configuration changes from default of the RAN550 you used with the example configs given in the repository.

Right now the RAN550 is getting the C/U traffic from srsRAN, however, srsRAN is not getting any valid packets back from the RAN550.
Since the Benetel configuration is rather confusing with many options for specific FlexRAN compatibility I'd simply like to make sure that things are configured as intended.

Specifically:
Currently the type of the RU is set to set_ru_config_RAN550_A_2x2_Ant1_3_FlexRAN which results in the script /usr/sbin/radio_setup_ran550_1_a_2x2_ant1_3.sh being executed.
However, this still sets the number of TXs to 4:

LOG_INFO "Set the Number of Tx's to 4 (C0300)"
/usr/bin/registercontrol -w C0300 -x 0x01010101

This also enables the udCompHdr option for PRACH (register c0352) while disabling PRACH compression (C0353 is set to 0).

It does stay at a long form PRACH.

The PRACH configuration index is originally set to 0xE, which srsRAN does not work, so we switched that to 7 as defined in the example configuration.

Then there are these two configurations:

LOG_INFO "Aligning TDD switching relative to downlink and uplink data and with respect to PPS (C0366)"
/usr/bin/registercontrol -w C0366 -x 0x1225
LOG_INFO "Aligning FPGA uplink timing to arrival of uplink frame(C0303)"
/usr/bin/registercontrol -w c0303 -x 0x24

and I'm really not sure what the correct setting for working with srsRAN would be here.

The TDD configuration /etc/tdd.xml was changed to

    <tdd-config version="1.0">
            <description>DDDDDDUUU</description>
                        <pattern index="1">
                                <slots>DDDDDDUUU</slots>
                                <numerology>1</numerology>
                                <periodicity>10</periodicity>
                                <special-slot-symbols></special-slot-symbols>
                        </pattern>
                        <pattern index="2">
                                <slots>DDDDDDUUU</slots>
                                <numerology>1</numerology>
                                <periodicity>10</periodicity>
                                <special-slot-symbols></special-slot-symbols>
                        </pattern>
    </tdd-config>

to match the 6-3 configuration given in the tutorial.

I'm aware that you're not the support for the RAN550 and I don't want you to give me support for the configuration, I'd just like to ask you to confirm if this is the same configuration you used when creating the example srsRAN configurations so that I can be sure that I'm matching that.

Thanks a lot for your time!

[ismagom]

In addition to this, please read amd follow RAN550 User Manual carefully. If in doubt, best would be to contact Benetel directly.

Thanks

[irrenhaus]

Hello again,

first, thanks for you help so far!

As discussed with Andre, here are the configurations we're currently using for trying to getting this to work.
For the core network we're using open5gs with its default configuration (might have changed the MCC/MNC/TAC to 001/01/1).

The behaviour currently is:

• srsRAN is connecting to the AMF without problems

• srsRAN is sending C/U plane packets to the RU and according to the kpi tool on the RU they're received on-time

• According to the tcpdump of these packets (
  enp177s0f0.pcap.txt, might have to rename due to file extension limitations) all IQ samples are all-0.

• The RU is not sending any packets to srsRAN (if is_prach_cp_enabled is set to true we're seeing ~2k4 packets/second on-time from the RU to srsRAN)

• We're having a look at the RF spectrum using a BladeRF SDR. According to that there is noise, a peak at the center frequency of the RU which is not related to starting/stopping traffic/srsRAN but only to the RF startup state of the RU and from time to time (not regular, roughly 5-10 seconds interval) there is a peak in activity over the whole bandwidth which does not look like there could be meaningful data in there, it looks more like there are peaks in noise coming from the RU. Example:
  

• The UE cannot see the network (quite obviously I guess)

In addition to the TDD pattern that is the default on the Benetel RU and documented as matching the PRACH configuration index 159 we've also tried using configuration index 7 and the 6-3 pattern as in your example configurations - see the benetel_tdd.6-3.xml.txt file attached. There was a difference in behaviour: If that configuration index was chosen, the RU was sending ~400 packets / second to the DU MAC as soon as it booted. srsRAN was receiving and marking them as too late and warned about them being not the correct size of IQ packets and being unable to decode them correctly. It seems these packets were due to a bug in the Benetel firmware.

If you have any ideas how we could continue to hopefully get this running it would be greatly appreciated!

Thanks
Nils / Xelera

benetel_config.sh.txt
gnb_ru_ran550_tdd_n78_100mhz_2x2.yml.txt
benetel_tdd.xml.txt
benetel_tdd-6.3.xml.txt
benetel_eaxc.xml.txt

[irrenhaus]

Hello again,

thanks a lot @ismagom, I did in fact set the affinities earlier, but it seems I chose the wrong NUMA node. Choosing the NUMA node where the NIC is connected to and upping the number up threads to the numbers you posted resolved the timing issues again.

However, this did not make any difference in terms of the RU.

I tried using a 20MHz 1x1, a 100MHz 1x1 and a 2x2 config, none of these result in the UE seeing any messages from the GNB while all parts of the system happily continue without any errors. The kpi counters in the RU still go up and say all messages are on-time.

Could you post the actual configuration of your RAN550?

The user documentation says only PRACH configuration indices 151, 156 and 159 are supported, so I'm using 151 with the 6-3 TDD pattern without a special slot.
But here the user documentation fails me: It says the prach configuration indices supported are defined by the TDD pattern being used, but what is written there does not actually work since srsRAN says that for these configs the slot indixes used for PRACH fall outside of the TDD UL slots. Also it only talks about a DDDDDDSUU configuration.

I'd like to have the setup as close as possible to what worked for you, so I'd be grateful if you could provide the tdd.xml & init script of your RU.

Thanks a lot!

[andrepuschmann]

Hey @irrenhaus - we've just done a small update to the appnote https://docs.srsran.com/projects/project/en/latest/tutorials/source/oranRU/source/index.html. Have a look at the RU section that now contains the configs we use for our device here.

[khooi8913]

Hi @irrenhaus,

Did you eventually manage to get things working with the RAN550 O-RU?
We are somewhat facing a similar issue too.
Thanks!

[ismagom]

Hi @khooi8913 , what issues are you facing exactly?

[pgawlowicz]

@irrenhaus Any update/feedback on this issue?

[khooi8913]

Hi @khooi8913 , what issues are you facing exactly?

Hi @ismagom , I have filed my issue in a separate discussion: #389.