gprs PACCH downlink assignment problem

Vladimir Rolbin vrolbin at gmail.com
Tue Oct 9 15:17:29 UTC 2012


Hi,

My set is openbts-p2.8-gprs-exp/osmo-pcu-jolly. I encounter the problem
with PACCH downlink assignment:

If the difference between FNs of DL_PACKET_DOWNLINK_ASSIGNMENT and
corresponding UL_PACKET_CONTROL_ACKNOWLEDGEMENT
is expected (RRBP = 0) 13 everything is OK (OpenBTS log):

1347379490.099008 3031505776: [ PCU -> BTS ] PACCH FN 2536893 FN52 21
CNTRL1 raw=(4f0800000c03400a0800802b2b2b2b2b2b2b2b2b2b2b2b)
DL_PACKET_DOWNLINK_ASSIGNMENT
1347379490.118500 3063704432: [ BTS -> PCU ] PhDataInd: FN 2536885 FN52 13
DATA raw=(100101cc741f3203c005650000014500003c00010000ff)
1347379490.136108 3063704432: [ BTS -> PCU ] PhDataInd: FN 2536889 FN52 17
DATA raw=(080105cc741f3228e2a8c8aa0100000100000000000003)
1347379490.154624 3063704432: [ BTS -> PCU ] PhDataInd: FN 2536893 FN52 21
DATA raw=(040107cc741f32777777066b616e6e656c036f72670000)
1347379490.215582 3063704432: [ BTS -> PCU ] PhDataInd: FN 2536906 FN52 34
CNTRL1
raw=(400731d07ccb2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b)UL_PACKET_CONTROL_ACKNOWLEDGEMENT


But it's not always the case

1349788219.582282 3043367792: [ PCU -> BTS ] PACCH FN 2189728 FN52 8 CNTRL1
raw=(4f0800000c02800a0d00802b2b2b2b2b2b2b2b2b2b2b2b)
DL_PACKET_DOWNLINK_ASSIGNMENT
1349788219.601978 3064179568: [ BTS -> PCU ] PhDataInd: FN 2189720 FN52 0
DATA raw=(040103ae3558373751f40103e800101773022a85464200)
1349788219.620378 3064179568: [ BTS -> PCU ] PhDataInd: FN 2189724 FN52 4
DATA raw=(0001042dae355837026a4e0432100000258ccc2b2b2b2b)
1349788219.638881 3064179568: [ BTS -> PCU ] PhDataInd: FN 2189728 FN52 8
DATA raw=(040103ae3558373751f40103e800101773022a85464200)
1349788219.680973 3064179568: [ BTS -> PCU ] PhDataInd: FN 2189737 FN52 17
CNTRL1 raw=(4006b8d560df2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b)
UL_PACKET_CONTROL_ACKNOWLEDGEMENT

diff FN = 9, that causes the following behaviour in pcu:

<0002> gprs_rlcmac_data.cpp:1753 TBF: START TFI: 0 TLLI: 0xae355837 Packet
Downlink Assignment (PACCH)
<0004> gprs_rlcmac_data.cpp:1442 Complete DL frame for TBF=0: len=9
<0002> gprs_rlcmac_data.cpp:281 PACKET CONTROL ACK with unknown FN=2163607
TLL=0xae355837 (TRX 0 TS 7)
<0002> gprs_rlcmac_data.cpp:100 Poll timeout for UL TBF=0
<0002> gprs_rlcmac_data.cpp:107 - Timeout for polling PACKET CONTROL ACK
for PACKET UPLINK ACK

Any ideas?  Is it the known issue?

Regards,
Vladimir Rolbin
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