[srsran-users] Requesting RRC Reestablishment as 0x46. Cause: otherFailure

Tue Nov 23 12:30:39 UTC 2021

Hey,

On 22/11/21 17:41, Antonio Albanese wrote:
> from the knowledge I could gain browsing the mailing list, I believe 
> the problem is that I have quite a number of underruns or lates, which 
> should be a signal that my CPU can't keep up with the 100 PRB 
> configuration.
> I have less problems with 50 PRBs (but still experience disconnections) 
> while it is almost completely stable with 25 PRBs.

Yes, that is usually what you would observe, i.e. improving stability 
with decreasing bandwidth.

Can you explain "almost completely stable"? Of course you're running the 
eNB on general purpose CPU and OS so some glitches are just expected but 
25 PRB should be - DSP wise - ok for a machine that "almost" runs 100 PRB.

> 
> I played with srsLTE already in the past and, as far as I remember, with 
> previous versions of srsLTE I could get much better stability by setting 
> the expert option /pregenerate_signals./
> However, on srsRAN, though present in the enb.conf example, it leads to 
> /unrecognised//option "expert.pregenerate_signals"/.
> 
> I see that it's been removed from the enb parser indeed. Is it intentional?

Yes, we've removed that feature over the last release(s). We measured 
the performance gain and decided it's not worth the increase in RAM 
usage, extra code, etc. The DSP is optimized and you should not see a 
significant performance hit. Could you perhaps share your setup details 
and logs?

It seems we forgot to remove the entry in the enb.conf.example. We'll 
fix that. Thanks for the hint.

Thanks
Andre

> 
> Thanks a lot,
> Antonio
> ᐧ
> 
> On Sun, 21 Nov 2021 at 19:02, Antonio Albanese 
> <antonioalbanese15 at gmail.com <mailto:antonioalbanese15 at gmail.com>> wrote:
> 
>     Hi guys,
> 
>     I'm experiencing the behavior in subject while running srsRAN with a
>     USRP B210 and an off-the-shelf UE.
>     I tested it with a Galaxy Tab S2 and an iPhone 12 with no
>     discernible difference.
> 
>     In particular, especially with /n_prb = 100/, I get RRC failures now
>     and then. I attached the eNB log right before and right after such a
>     disconnection.
>     I'm working on an application that requires high radio stability and
>     high bandwidth to estimate the distance between the eNB and the UE
>     via DMRS. While experimenting I could see that the estimated
>     distance by the crosscorrelation lag between the received DMRS and
>     the local DMRS copy kind of drifted with time, which I would ascribe
>     to one party not being able to keep its TTI-level synchronization.
>     The host is an /Intel NUC7i7DNBE/ and is completely dedicated to the
>     task. The behavior is still there even with a clean version of
>     srsRAN without any source code edits.
> 
>     I also attach the eNB configuration. I tried playing with the
>     /device_args /setting it to /num_recv_frames=64,num_send_frames=64
>     /with no luck.
> 
>     Any help would be much appreciated.
> 
>     Thank you,
>     Antonio
> 
>     -----------------------------------------------------------------------------------------------------------------------------
> 
> 
>     linux; GNU C++ version 5.4.0 20160609; *Boost_105800*;
>     *UHD_003.009.007-6-g9ebbb8eb
>     *
>     ---  Software Radio Systems LTE eNodeB  ---
> 
>     Couldn't open , trying /home/nuc/.config/srsran/enb.conf
>     Reading configuration file /home/nuc/.config/srsran/enb.conf...
>     Couldn't open sib.conf, trying /home/nuc/.config/srsran/sib.conf
>     Couldn't open rr.conf, trying /home/nuc/.config/srsran/rr.conf
>     Couldn't open rb.conf, trying /home/nuc/.config/srsran/rb.conf
> 
>     Built in Release mode using commit 5275f33 on branch master.
> 
>     /home/nuc/srsRAN/srsenb/src/enb_cfg_parser.cc:1216: Force DL EARFCN
>     for cell PCI=1 to 1800
>     Opening 1 channels in RF device=default with args=default
>     Available RF device list: UHD  zmq
>     Trying to open RF device 'UHD'
>     Opening USRP channels=1, args: type=b200,master_clock_rate=23.04e6
>     -- Detected Device: B210
>     -- Operating over USB 3.
>     -- Initialize CODEC control...
>     -- Initialize Radio control...
>     -- Performing register loopback test... pass
>     -- Performing register loopback test... pass
>     -- Performing CODEC loopback test... pass
>     -- Performing CODEC loopback test... pass
>     -- Asking for clock rate 23.040000 MHz...
>     -- Actually got clock rate 23.040000 MHz.
>     -- Performing timer loopback test... pass
>     -- Performing timer loopback test... pass
>     RF device 'UHD' successfully opened
> 
>     ==== eNodeB started ===
>     Type <t> to view trace
>     Setting frequency: DL=1865.0 Mhz, UL=1770.0 MHz for cc_idx=0 nof_prb=100
>     RACH:  tti=10011, cc=0, preamble=44, offset=1, temp_crnti=0x46
>     User 0x46 connected
>     RACH:  tti=5421, cc=0, preamble=22, offset=1, temp_crnti=0x47
>     User 0x47 requesting RRC Reestablishment as 0x46. Cause: otherFailure
>     Disconnecting rnti=0x46
>     ᐧ
> 
> 
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-- 
Andre Puschmann

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

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