itcf parameter tc drops
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8/10/2019 ITCF Parameter TC Drops
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NOKIA Presentation_Name.PPT / DD-MM-YYYY / Initials Company Confidential
ITCF parameterNUMBER OF IGNORED TRANSCODER FAILURE (ITCF)
This Parameter is used to check how many Transcoder Failure the systemwill receive before it Releases the calls.
Explanation:
After a speech path connection has been established between the BTS and the TC,they try to align with each other to enable speech coding both in uplink and downlinkdirections. If the alignment procedure fails, speech decoding also fails and speech isno longer audible. In this case, the BTS sends CONNECTION_FAILURE_INDICATIONmessage to the BSC. The BSC requests for a clearing and then releases the resourcesconnected to the call. The cause field in this failure indication message is "REMOTETRANSCODER FAIL”
When more aggressive HR is introduced, due to the interference in the air interfaceand signaling messages can be lost. Re-sending the messages one or more times canlengthen the call establishment dramatically and this might lead to trigger of REMOTETRANSCODE FAIL counters.
If parameter ITCF is set to 0 (default), the call clearing procedure will be triggeredimmediately when CONNECTION_FAILURE_INDICATION message (with causetranscoder failure) is received from BTS. Otherwise, BSC will not release the ongoingcall until the number of CONNECTION_FAILURE_INDICATION messages (with causetranscoder failure) received exceeds ITCF. BTS repeats the message at one-secondintervals. If the frame synchronization is obtained again or the call is released, thecounting of remote transcoder failure causes begins from zero again.
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ITCF parameter
Advantage & Disadvantage if ITCF
[ ITCF=4 ]
• If the circuit is really faulty the call will be released after the BSC receives the fourCONNECTION_FAILURE_INDICATION message from the TC. So in this case call willcontinue on the Time slot for some time ( till 4 messages are not received) even if theBSC knows that the circuit is faulty.
• Secondly if the circuit is affected by a short term disturbance ( eg. short termtransmission disturbance) which causes a loss of TRAU frame synchronization the callwill NOT be released by the system.
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ITCF parameter
ITCF testing results on Mumbai Network
Settings in all the BSCs, ITCF = 0 On 13/02/06 ITCF settings were changed to 2 for all BSC in Mumbai Network.
Observation: Drop in no of Tr_Fail and Tch drop have improved.
Nokia Recommend to change the settings to 2 on all BSCs where we have aggressive HR.
Reduced Tr_Fail
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2 / 6 / 2 0
0 6
2 / 7 / 2 0
0 6
2 / 8 / 2 0
0 6
2 / 9 / 2 0
0 6
2 / 1 0 / 2 0 0
6
2 / 1 1 / 2 0 0
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2 / 1 2 / 2 0 0
6
2 / 1 3 / 2 0 0
6
2 / 1 4 / 2 0 0
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2 / 1 5 / 2 0 0
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2 / 1 6 / 2 0 0
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Date
N o . o
f T r a n s c o d e r F a i l u r e s
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Date BSC
Tch
drp
tr_
fail BSC
Tch_
drp
tr_
fail BSC
Tch_
drp
tr_
fail BSC
Tch_
drp
tr_
fail
04/02/2006 BSC33KRT 1.20 1923 BSC29SPT 0.93 217 BSC28SLA 0.96 917 BSC31TRI 1.14 806
05/02/2006 BSC33KRT 1.21 2063 BSC29SPT 0.90 312 BSC28SLA 0.75 116 BSC31TRI 1.01 873
06/02/2006 BSC33KRT 1.30 2314 BSC29SPT 0.93 266 BSC28SLA 1.03 862 BSC31TRI 1.11 857
07/02/2006 BSC33KRT 1.22 2431 BSC29SPT 0.93 543 BSC28SLA 0.95 1360 BSC31TRI 1.25 1148
08/02/2006 BSC33KRT 1.29 3684 BSC29SPT 0.93 314 BSC28SLA 0.85 860 BSC31TRI 1.24 778
09/02/2006 BSC33KRT 1.23 3263 BSC29SPT 0.93 492 BSC28SLA 0.78 452 BSC31TRI 1.10 899
10/02/2006 BSC33KRT 1.04 1603 BSC29SPT 0.93 368 BSC28SLA 0.82 1055 BSC31TRI 1.10 1430
11/02/2006 BSC33KRT 0.95 605 BSC29SPT 0.88 424 BSC28SLA 0.79 312 BSC31TRI 1.16 715
12/02/2006 BSC33KRT 1.00 572 BSC29SPT 0.86 327 BSC28SLA 0.66 45 BSC31TRI 0.93 666
13/02/2006 BSC33KRT 0.96 519 BSC29SPT 0.89 48 BSC28SLA 0.82 248 BSC31TRI 1.12 102
14/02/2006 BSC33KRT 1.05 520 BSC29SPT 0.95 27 BSC28SLA 0.89 34 BSC31TRI 1.15 18
15/02/2006 BSC33KRT 0.98 481 BSC29SPT 0.89 15 BSC28SLA 0.81 26 BSC31TRI 1.07 85
16/02/2006 BSC33KRT 0.90 9 BSC29SPT 0.85 11 BSC28SLA 0.78 19 BSC31TRI 1.04 17