Bug #3370

osmo-bts "substituting all-zero burst" and osmo-pcu "Link quality (0dB) left window [5, 8], modifying uplink CS levels: CS-2 -> CS-1"

Added by rlehm over 2 years ago. Updated about 1 year ago.

Target version:
Start date:
Due date:
% Done:


Spec Reference:


Running newest versions of LimeSuite, osmo-nitb, osmo-bts-trx, osmo-trx-lms, osmo-pcu, osmo-sgsn, and osmo-ggsn on a LimeSDR-USB. GSM capabilities work as normal, but once osmo-bts-trx connects to osmo-pcu the bts outputs:

20/16 Substituting all-zero burst (current_fn=1527981, elapsed=2
<0007> scheduler.c:917 1528136/1152/12/23/20 Substituting all-zero burst (current_fn=1528137, elapsed=2
<0007> scheduler.c:917 1528162/1152/12/49/46 Substituting all-zero burst (current_fn=1528163, elapsed=2
<0007> scheduler.c:917 1528188/1152/12/24/20 Substituting all-zero burst (current_fn=1528189, elapsed=2

and pcu outputs:
<0001> pcu_l1_if.cpp:390 RACH request received: sapi=1 qta=0, ra=123, fn=1528801, cur_fn=1528804, is_11bit=0
<0008> tbf.cpp:977 Allocating UL TBF: MS_CLASS=0/0
<0008> tbf.cpp:538 TBF(TFI=0 TLLI=0x00000000 DIR=UL STATE=NULL) Setting Control TS 5
<0008> tbf.cpp:923 TBF(TFI=0 TLLI=0x00000000 DIR=UL STATE=NULL) Allocated: trx = 0, ul_slots = 20, dl_slots = 00
<0008> bts.cpp:746 TBF(TFI=0 TLLI=0x00000000 DIR=UL STATE=FLOW) set ass. type CCCH [prev CCCH:0, PACCH:0]
<0008> bts.cpp:754 TBF(TFI=0 TLLI=0x00000000 DIR=UL STATE=FLOW) TX: START Immediate Assignment Uplink (AGCH)
<0008> tbf.cpp:647 TBF(TFI=0 TLLI=0xe70c9306 DIR=DL STATE=WAIT RELEASE) T3193 timeout expired, freeing TBF
<0008> tbf.cpp:482 TBF(TFI=0 TLLI=0xe70c9306 DIR=DL STATE=RELEASING) free
<0007> gprs_ms.cpp:672 MS (IMSI ): Link quality 0dB (0dB) left window [5, 8], modifying uplink CS level: CS-2 -> CS-1
<000a> tbf_ul.cpp:295 TBF(TFI=0 TLLI=0x00000000 DIR=UL STATE=FLOW) Decoded premier TLLI=0x00000000 of UL DATA TFI=0.
<000c> tbf_ul.cpp:392 LLC [PCU -> SGSN] TBF(TFI=0 TLLI=0xd274c680 DIR=UL STATE=FLOW) len=78
PayloadType = 1 | spare = 0 | R = 0 | MESSAGE_TYPE = 1 | TLLI = 0xd274c680 | CTRL_ACK = 3 | Exist_AdditionsR5 = 0 | Padding = 43|43|43|43|43|43|43|43|43|43|43|43|43|43|43|43|43|
<0007> gprs_rlcmac_meas.cpp:106 UL RSSI of TLLI=0xd274c680: -40 dBm

over and over again (with some payload data in between). The SGSN and GGSN server don't appear to be receiving any packets and the phone does not have data.

I'm using the default .cfg files provided by myriadrf and have set all the necessary iptables rules for forwarding traffic through the GGSN tunnel.

Related issues

Related to OsmoBTS - Feature #3428: Implement handling of NOPE / IDLE indications from TransceiverResolved07/28/2018


#1 Updated by laforge over 2 years ago

#2 Updated by fixeria over 2 years ago

  • Related to Feature #3428: Implement handling of NOPE / IDLE indications from Transceiver added

#3 Updated by laforge over 1 year ago

  • Project changed from Cellular Network Infrastructure to OsmoPCU
  • Assignee set to lynxis
  • Priority changed from Normal to Low

#4 Updated by fixeria over 1 year ago

  • Project changed from OsmoPCU to OsmoBTS
  • Category set to osmo-bts-trx
  • Status changed from New to Feedback

Hi @rlehm,

could you please test with the recent versions?

I while ago I've merged a patch for OsmoBTS that disables burst substituting on PDCH time-slots. This is not really needed (and moreover was not implemented properly).

#5 Updated by fixeria about 1 year ago

  • Status changed from Feedback to Closed

Closing due to the lack of feedback. I am pretty sure the problem has been fixed. Please reopen otherwise.

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