How to perform trouble shooting based on counters

1. Company Confidential
How to performtrouble shooting based on counters
• Pre-requisite: Capture ALL the measurement dumps (e.g.,
ServLev, CellRes, RRC, L3 signalling, etc)
• Calculated each PI with the breakdown on the failure
cause(s)

2. Company Confidential
RRC Connection Setup Phase
• RRC Connection Setup Phase is from RRC Connection
Request to RRC Connection Setup message
• In the RRC Connection Setup Phase, there are 8 possible
setup failure causes
• For each failure cause, we can look into analyzing (or
trouble shooting the Top-N cells) 8 failures causes

3. Company Confidential
1. RRC_CONN_STP_FAIL_AC
• For e.g, in the previous slide, we see that there were
1085 RRC Setup failure due to AC reason
• Then we zoom into Top-N cells for further analysis. For
instance, the worst cell is WBTS: 110B9WC, WCEL-3

4. Company Confidential
RRC_CONN_STP_FAIL_AC
• First check the alarm history is there any alarm
happened to this site/cell on that day
• Once confirmed there was alarm happened, you may skip
to analyze this site/cell. This is because when alarm
happened, no one can confirm it affects the way
counter is triggered or not
• Check any parameter(s) error.
• Failure due to AC has to be further analyzed is because
of UL or DL
• Next, we look into Cell Resource table on this WCEL (i.e.
110B9WC-3)
• For UL, then we will look into AVE_PRX_NOISE,
MAX_PRX_NOISE_VALUE, MIN_PRX_NOISE_VALUE, and
AVE_PRXTOT_CLASS_x, where x is from 0 to 4 (a sample
will be presented in next slide)
• For DL, then we will look into AVE_PTXTOTAL_CLASS_x

5. Company Confidential
Prxtotal Performance
• The Prxnoise look quite reasonable, i.e., no high noise. The
max. & min. noise is also quite alright. So the failure is
likely not in UL
• Next, look at Ptxtotal (DL) performance
Actual value=(value/100) then put a ve sign??–

6. Company Confidential
Ptxtotal Performance
• The sample in class 3 is quite high. Indicate there could
be DL power issue (AC rejection due to DL)
Some problem in term
of value here??

7. Company Confidential
RRC_CONN_STP_FAIL_AC
• Next, check the M1002 (Traffic table)
• Check M1002C1 DCH Request for Signalling Link Reject in UL
(DCH_REQ_LINK_REJ_UL_SRNC)
• Check M1002C2 DCH Request for Signalling Link Reject in DL
(DCH_REQ_LINK_REJ_DL_SRNC)
• From the traffic table, we can conclude that the AC reject
is due to DL (proven that the guessing in previous slide is“ ”
correct
• Suggestion: Try to tune Ptxtarget to a high value (if there is
still room to tune) and monitor the performance
• Note: It could be BTS problem as well (like WSP, BTS s/w
problem, etc). But this should be solved by the latest BTS s/w
release.

8. Company Confidential
AnotherExample on Failure Due To AC (UL Problem)
Suspect it is due to UL
Because there is Class_4
triggered
Confirmed from
Traffic measurement

9. Company Confidential
2. RRC_CONN_STP_FAIL_BTS
• The second failure cause for RRC Connection Setup is due to
BTS reason
• Check alarm history if there is any alarm happened to this
site/cell on that day
• Once confirmed there was alarm, you may skip to analyze this
site/cell. This is because when alarm happened, no one can
confirm it affects the way counter is triggered or not
• Check L3 Iub counter (M1005) for the followings
• M1005C10 RL Setup Fail for 1st
RL due to O&M intervention
(SETUP_FAIL_RL_O_M_INTERV)
• M1005C11 RL Setup Fail for 1st
RL due to already active
(SETUP_FAIL_RL_ALREADY_ACTIV)
• M1005C12 RL Setup Fail for 1st
RL due to HW resource not available
(SETUP_FAIL_FIRST_RL_HW_RES)
• M1005C13 RL Setup Fail for 1st
RL due to not enough resource
(SETUP_FAIL_RL_NOT_ENOUGH_RES)
• M1005C14 RL Setup Fail for 1st
RL due to BTS not responding
(SETUP_FAIL_RL_BTS_NOT_RESP)
• M1005C15 RL Setup Fail for 1st
RL due to BTS general reason
(SETUP_FAIL_RL_BTS_GEN_REA)
• Sometimes failure could be due to wrong configuration data in
BTS. If still fail due to not enough resource (no alarm), then
check configuration data

10. Company Confidential
RRC_CONN_STP_FAIL_BTS
May need to chec
BTS alarm!!!

11. Company Confidential
3. RRC_CONN_STP_FAIL_TRANS
• Check BTS/AXC/Transmission alarm history
• Check physical layer for ATM alarms and link error“
seconds”
• Normally happen to site with 2xE1 IMA links
• Check parameters setting (esp. COCO, TRS related) vs.
planned value
• Could be due to TRS capacity bottle neck. Need to
confirm will this trigger M1001C5 or C399?
• Check UNI measurement (M548)??
• See next slide for parameter mismatched case

12. Company Confidential
RRC_CONN_STP_FAIL_TRANS
2xE1 config here
But 1xE1 setting in
AAL2 UP

13. Company Confidential
4. RRC_CONN_STP_FAIL_HC
• Problem at initial link setup inside RNC handover program
block (HA3)
• Usually a data build issue, e.g. CellID (wcel does not exist)
• This counter shouldn t be triggered’
• Suggestion: Check RNC data build for failure cell

14. Company Confidential
5. RRC_CONN_STP_FAIL_RNC
• Check BTS & RNC alarm history
• Difficult to trouble shoot as this is likely due to some
RNC unit alarm
• Could be due to parameter mismatch (what
parameter???), timer expiry, L2 problem, etc

15. Company Confidential
6. RRC_CONN_STP_FAIL_FROZBS
• Check BTS alarm
• Based on counter description, this counter seems only
trigger when AC block call setup to ensure the setup
of emergency calls
• Never encounter this counter triggered yet. Likely to
observe it when there is high load in the system AND
also emergency calls initiated

16. Company Confidential
7. RRC_CONN_STP_FAIL_RNTI_ALLO
• Check RRMU loading
• Check RNC alarm??? (any RRMU unit restart, etc??)
• Never encounter this counter triggered yet

17. Company Confidential
8. SPARE_1_SERVICELEVEL
• This counter represents RRC Setup Fail due to Iub AAL2
Transmission reason
• Never encountered this counter triggered yet. Why?
Need to load the right OSS s/w & CD level??
• May have to cross check with M1001C5
RRC_CONN_STP_FAIL_TRANS (RRC Connection Setup Failure
due to Transmission reason) to determine which counter
is triggered
• Check BTS/AXC/TRS alarm
• Check AXC/TRS related parameter consistency (like the
case in failure due to TRS reason)

18. Company Confidential
RRC Connection Access Phase
• In RRC Connection Access Phase, there are 3 failures
causes
• M1001C9 RRC_CONN_ACC_FAIL_RADIO (RRC Connection Access Failure
due to radio interface synchronization)
• M1001C10 RRC_CONN_ACC_FAIL_MS (RRC Connection Access Failure due
to Uu interface)
• M1001C11 RRC_CONN_ACC_FAIL_RNC (RRC Acc Fail due to RNC Internal
Reason)

19. Company Confidential
1. RRC_CONN_ACC_FAIL_RADIO
• Check RRC Access failure per
establishment cause to
determine whether failure is
mainly due to inter-RAT cell
reselection or registration,
etc
• If there is high
attempts/failures on the
inter-RAT cell reselection or
registration, then likely to be
coverage issue
• May indicate the inter-RAT
cell reselection parameter
need to optimized in case
high inter-RAT cell reselection
attempts/failures
Distribution for Establishment Cause
36%
17%
12%
8%
7%
3%
2%
2%
2%
2%2%1%1%1%1%1%1%0%0%0%0%0%0%0%0%0%0%0%0%0%0%0%0%0%0%0%0%0%0%
intr_rat_cell_re_select_c
radio_interface_c
registration_c radio_interface_c
registration_c ms_c
intr_rat_cell_re_select_c ms_c
orig_conversational_call_c
radio_interface_c
orig_conversational_call_c ms_c
orig_high_prior_signal_c
radio_interface_c
term_conversational_call_c
radio_interface_c
term_conversational_call_c
ms_c
term_low_prior_signal_c ms_c
term_low_prior_signal_c
radio_interface_c
orig_low_prior_signal_c
radio_interface_c
orig_high_prior_signal_c ms_c
orig_interactive_call_c ms_c
orig_low_prior_signal_c ms_c
orig_interactive_call_c
radio_interface_c
detach_c radio_interface_c
call_re_establishment_c
radio_interface_c
term_interactive_call_c ms_c
detach_c ms_c
orig_background_call_c
radio_interface_c
term_interactive_call_c
radio_interface_c
call_re_establishment_c ms_c
term_background_call_c
radio_interface_c
term_cause_unknown_c
radio_interface_c
orig_background_call_c ms_c
Likely be coverage issue

20. Company Confidential
RRC_CONN_ACC_FAIL_RADIO
• Check any parameter inconsistent
• Check Prxnoise, and Ptxtot performance
• Probably can tune T312 to 6sec & N312=2 or 1 to see any
performance improvement
• Perform drive test to confirm any DL coverage problem.
It could be due to UE not receiving RRC Connection
Setup message (i.e., SCCPCH power not enough) -> Tune
SCCPCH power if required
• Failure could be UE model related. Reason: Some UE models
perform badly when the RF performance is no good (e.g.,
when Ec/No < -11dB). Need to use Traffica/ICSU log to
confirm UE model. This check is tedious and should be
done only after all checks and the problem still
occurring.
• In some projects, it has noticed that Sony Ericsson
Z1010 perform badly when RF is weak (similarly to other
models on EMP Ericsson Mobile Platform, eg. LG) see– –

21. Company Confidential
RRC_CONN_ACC_FAIL_RADIO
• Different UE performance vs. initial Ec/No
Success Rate for Initial Synch in RRC Access :
Nokia/LG
50.00
55.00
60.00
65.00
70.00
75.00
80.00
85.00
90.00
95.00
100.00 -25
-22
-20
-17
-15
-12
-9.5
-7
-4.5
-2EcNo
SuccessRate%
Nokia 6630, 6680
Nokia 7600
LG 8130, 8138, 8180,
8330
LG U8110, 8120

22. Company Confidential
2. RRC_CONN_ACC_FAIL_MS
• This failure should be much lesser than L1 synch problem
• It is triggered when RNC received NBAP: Synchronization
Indicator. BUT there is no RRC Connection Setup
Complete received
• Check any UL interference
• It indicates there is some problem with UL coverage.
Try to tune CPICH to have more balance between UL &
DL coverage (if it is not UL interference)
• Maybe due to BTS problem. Try to reset the WBTS to
see problem still exist
• May due to WSP problem (refer to John s WBTS trouble’
shooting for 35003WC)

23. Company Confidential
3. RRC_CONN_ACC_FAIL_RNC
• Normally this counter does not have high triggers
• If there is high failure due to RNC, pls check RNC alarm

24. Company Confidential
RRC Connection Active Phase
• RRC Active Phase has 8 failure causes
• M1001C15 RRC Active Fail due to Iu Interface–
(RRC_CONN_ACT_FAIL_IU)
• M1001C16 RRC Active Fail due to Radio Interface–
(RRC_CONN_ACT_FAIL_RADIO)
• M1001C17 RRC Active Fail due to BTS Reasons–
(RRC_CONN_ACT_FAIL_BTS)
• M1001C18 RRC Active Fail due to Iur Interface–
(RRC_CONN_ACT_FAIL_IUR)
• M1001C19 RRC Active Fail due to Ciphering Fail–
(RRC_CONN_ACT_FAIL_CIPH)
• M1001C20 RRC Active Fail due to Integrity Check–
(RRC_CONN_ACT_FAIL_I_CHK)
• M1001C21 RRC Active Fail due to RNC Internal Reasons–
(RRC_CONN_ACT_FAIL_RNC)
• M1001C391 RRC Active Fail due to UE–
(RRC_CONN_ACT_FAIL_UE)
• Majority of the failures seem to be:
• RNC Internal

25. Company Confidential
RRC Connection Active Phase
Majority of failures
This counter
is not triggere
Correctly in
RN2 GCD1.0

26. Company Confidential
RRC_CONN_ACT_FAIL_IU
• Generally is signaling connection fails between the RNC
and CN
• Next to check RNC & CN alarm. In case the problem
happen consecutively for many days (eg. 4 to 5 days)
and the same cells. Then some ICSU logs need to take
on the particular WBTS/WCEL to find out the root
cause
• Wrong parameter setting in MSC (INFO IN SCCP C-REF
MESSAGE SUPPORTED was enable), this counter was
incremented during the detach procedure nevertheless
the detach was successfully - Need confirmation???

27. Company Confidential
RRC_CONN_ACT_FAIL_RADIO
• In general, this is due to radio link failure because of loss of“ ”
L1 synchronization
• Need to check coverage
• This is the top 1 failure in most of the network
• Possible cause could also be due to some UE not responding to
Radio Bearer Reconfiguration message from RNC
• Check the Radio Bearer Reconfiguration Success Rate from
RRC (M1006) table: 100*(RB_RECONF_COMPLETE/RB_RECONF). If the
success rate is very low, this is very likely due to UE not
responding to RB Reconfiguration message. It could be either
UE problem or coverage issue
• CPICHToRefRABOffset is 0dB (new default) which give 2dB more
power than the old default value. Hopefully this can provide
more power to sustain a call in poor coverage area
• If the problem continuously happen to a WBTS/WCEL for many
days. Perform a drive test to check any coverage issue. Else,
ICSU log need to be taken and analyze the PMI ticket to see
the high failure cause

28. Company Confidential
RRC_CONN_ACT_FAIL_RNC
• Check RNC alarm
• Typically this is due to some timer expired in RNC
• Check is the failure also happen to WBTS/WCEL near to
RNC border
• For e.g., SRNC relocation failure may result in this
counter incremented (t_reloc_prep timer expired)
• It may be due to some timer value set too small in RNC.
For e.g., Iu-PS signaling cell delay variation time
• Check L3 SRNC relocation counter??? (additional
information need to be added here. Will be added in
future!!!)

29. Company Confidential
RRC_CONN_ACT_FAIL_BTS
• Normally this is failed due to BTS alarm
• So far this cause is not the majority

30. Company Confidential
RRC_CONN_ACT_FAIL_Iur
• No idea for trouble shooting yet
• Could be related to inter-RNC SHO or SRNC relocation or
anchoring problem

31. Company Confidential
RRC_CONN_ACT_FAIL_I_CHK
• No failure yet
• If failure occurred, likely to be some system or UE
issue??
• Integrity check is not RF issue

32. Company Confidential
RRC_CONN_ACT_FAIL_CIPH
• No failure yet
• If failure occurred, then likely to by system or UE
issue
• Ciphering is not RF issue

33. Company Confidential
RRC_CONN_ACT_FAIL_UE
• This counter is not trigger correctly in RAN04 GCD1.0
• GCD2.0 or 2.1 will have correction
• Currently this is due to no response of RRC message
from UE
• But Cell FACH <-> Cell DCH transition will also cause this
counter to be updated -> causing inaccuracy