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Bug #4955

closed

CSN1 Error observed: NEED_MORE BITS TO UNPACK (-5) at DL_DualCarrierForDTM

Added by keith 11 months ago. Updated about 1 month ago.

Status:
Closed
Priority:
Normal
Assignee:
Target version:
-
Start date:
01/18/2021
Due date:
% Done:

0%

Spec Reference:

Description

Repeats 4 times. Also no newline at the end of this log line:

DCSN1 <0000> ../../git/src/csn1.c:1468 csnStreamDecoder: error NEED_MORE BITS TO UNPACK (-5) at DL_DualCarrierForDTM (idx 71)DCSN1 <0000> ../../git/src/csn1.c:1468 csnStreamDecoder: error NEED_MORE BITS TO UNPACK (-5) at DL_DualCarrierForDTM (idx 71)DCSN1 <0000> ../../git/src/csn1.c:1468 csnStreamDecoder: error NEED_MORE BITS TO UNPACK (-5) at DL_DualCarrierForDTM (idx 71)DCSN1 <0000> ../../git/src/csn1.c:1468 csnStreamDecoder: error NEED_MORE BITS TO UNPACK (-5) at DL_DualCarrierForDTM (idx 71)

Assigning to myself at least until I add a pcap.


Files

QPSK_MEAN_BEP.pcap QPSK_MEAN_BEP.pcap 65.4 KB frame #228 keith, 01/24/2021 09:14 PM
p32QAM_HSR_CV_BEP.pcap p32QAM_HSR_CV_BEP.pcap 261 KB keith, 01/24/2021 10:57 PM
DL_DualCarrierForDTM.pcap DL_DualCarrierForDTM.pcap 797 KB keith, 01/24/2021 11:49 PM

Related issues

Related to OsmoPCU - Bug #5250: osmo-pcu: CSN.1 decoder failure parsing specific RAcapResolvedpespin10/07/2021

Actions
Actions #1

Updated by keith 10 months ago

Another CSN Error observed. Need to try to grab a pcap of this one too.

DCSN1 <0000> ../../git/src/csn1.c:252 csnStreamDecoder: error NEED_MORE BITS TO UNPACK (-5) at p32QAM_HSR_CV_BEP (idx 182)
DRLCMACUL <0005> ../../git/src/pdch.cpp:712 Dropping Uplink Control Block with invalid content, decode failed: -5)
Actions #2

Updated by keith 10 months ago

and:

csnStreamDecoder: error NEED_MORE BITS TO UNPACK (-5) at QPSK_MEAN_BEP (idx 181)DRLCMACUL
Actions #6

Updated by fixeria 10 months ago

  • Status changed from New to In Progress
  • Assignee changed from keith to fixeria

It looks pretty much like a mistake in TS 44.060:

The payload is: '4017e5b2cd5a2eca68655e44aec84880139300412b2b2b'O.

Actions #7

Updated by keith 10 months ago

Another Payload observed is

x2f x83 x61 xfa x14 x14 x26 x86 x56 x4b x2c xcc x00 x40 x01 x70 x0b x2b x2b x2b x2b x2b

(formatted for pasting into http://lte-3gpp.info/decode_ts44060.php)

This is the case of the DL_DualCarrierForDTM Error, is observed regularly and is an MS RAC IE.

While the other errors are always followed in the log with "Dropping Uplink Control Block with invalid content...", this one is not. Wireshark decodes the payload correctly. An example payload can be found in the pcap, towards the end.

Actions #8

Updated by fixeria 10 months ago

  • Status changed from In Progress to Feedback
  • Assignee changed from fixeria to keith

Here is my attempt to fix 'QPSK_MEAN_BEP' related decoding errors: https://gerrit.osmocom.org/c/osmo-pcu/+/22524.

Unfortunately, I don't have time to work on this anymore :/

Best regards,
Vadim.

Actions #9

Updated by keith about 2 months ago

I'm not sure if @fixeria's patch got implemented elsewhere.

The most commonly seen CSN error now is

<0000> ../../git/src/csn1.c:252 csnStreamDecoder: error 
NEED_MORE BITS TO UNPACK (-5) at MultislotCapabilityReductionForDL_DualCarrier (idx 64)
Actions #10

Updated by pespin about 2 months ago

  • Related to Bug #5250: osmo-pcu: CSN.1 decoder failure parsing specific RAcap added
Actions #11

Updated by pespin about 1 month ago

Similar issues should be fixed by these commits:
https://gerrit.osmocom.org/c/osmo-pcu/+/25716 csn1: Add unit test showing RadioAccess Capability decoding failure
https://gerrit.osmocom.org/c/osmo-pcu/+/25830 csn1: Avoid failing if optional DownlinkDualCarrierCapability_r7 is missing
https://gerrit.osmocom.org/c/osmo-pcu/+/25831 csn1: Avoid storing existance bit as true if content was actually NULL

Please keith , if after merging it you still see problems, report a pcap file containing the relevant packets. We'll then probably need to change the CSN1 description for a few more fields in RAcap as we see we need it.

Actions #12

Updated by keith about 1 month ago

  • Status changed from Feedback to Closed

This issue looks most likely fixed with the above patches.
Let continue if needed in #5250

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