Download - Alcatel WCDMA KPI Evaluation 3G WCDMA
Krishna K Jayachandran
KPI evaluation 3G WCDMA
All Rights Reserved © Alcatel-Lucent 2008
Source: Huawei
All Rights Reserved © Alcatel-Lucent 2008
KPI Structure
All Rights Reserved © Alcatel-Lucent 2008
CS Call set up diagram
Source: T Mobile documentation ( Public)
All Rights Reserved © Alcatel-Lucent 2008
PS Call set up diagram
Source: T Mobile documentation ( Public)
All Rights Reserved © Alcatel-Lucent 2008
Accessibility
Ability of user to obtain the requested service from the system. RRC ( Radio Resource Control) RAB ( Radio Access Bearer)- defines type of service Main KPIs CSV Access Failure Rate, CSD Access Failure Rate, PS Access Failure
Rate, HSDPA Access Failure Rate, HSUPA Access Failure Rate, CS RAB set up success ratio, PS RAB set up success ratio, RRC Congestion Ratio
All Rights Reserved © Alcatel-Lucent 2008
Voice Access Failure
CS Voice RRC Failure
Voice RAB Failure
CS RRC Setup or
RRC Access?
RRC or RAB?
CS RRC Setup Failure
CS RRC Access Failure
Voice RAB Setup Failure
Voice RAB Access Failure
Voice RAB Setup or RAB Access?
RRC Failure / Adm Contro
l
RRC Failure
/ Licens
e
RAB Failure
/ DL Code
RRC&RAB
Failure / TN
Blocking
RAB Failure
/ DL Pwr
RAB Failure
/ Hardwa
re Resour
ce
RRC&RAB Setup Failure Cause
Analysis RRC Access Failures are mostly due to radio reasons. RAB Access
Failures are due to both radio and core network reasons.
Troubleshooting flow chart
All Rights Reserved © Alcatel-Lucent 2008
Sample formula
All Rights Reserved © Alcatel-Lucent 2008
Failure causes
RRC failures causes: Admission control. Uplink issues.
RAB failures. Admission control: Main causes : power, codes, Channel elements. Example of Mumbai circle with wrong test license loaded on 2 cells.
CE capacity increased from 30 to 192.
All Rights Reserved © Alcatel-Lucent 2008
Example # 1 ( Accessibility)
Alarm: System dynamic traffic exceeding licensed limit
All Rights Reserved © Alcatel-Lucent 2008
Remedial action
Congestion- EDT/MDT, CPICH ( only when absolutely necessary) for power, addition of HW for codes, checking SW licenses for Channel elements.
All Rights Reserved © Alcatel-Lucent 2008
Retainability
Ability of a user to retain its requested service for the desired duration once connected.
Key issues are missing neighbors, low quality, Hw issues and alarms, Transport issues.
Main KPIs: CSV Drop Rate, CSD Drop Rate, HSDPA Call drop ratio, HSUPA call
drop ratio, PS R99 call drop ratio.
All Rights Reserved © Alcatel-Lucent 2008
Drop Cause
Voice Drop
Missing Neigh
RL Add Failure UL Sych IRAT
DropIur Drop
Other Drop
Analyze existing
neighbors with 3G-3G cell relation reportAnalyze
cell coverage
by RF Planning tool or
DrivetestDown tilts or other physical
optimization
Check BTS HW Alarms
Check Transmission Errors
Check Cell Availabilit
y
Investigating the UE TxPwr by
using Drivetest
Analyze cell
coverage by RF
Planning tool or
Drivetestdetermine the
number of Event 6a
or number of Event
2d
Neighbor List
cleaning/ deletion
GSM coverage
area verification for IRAT neighborsRe-prioritizati
on the neighbor list based on usage
Transport Issue
RBS / RNC HW issue
RF issues outside of provided counters
UE issues
Check Iur drop per Iur link
Check neighbor
cell availability
All Rights Reserved © Alcatel-Lucent 2008
All Rights Reserved © Alcatel-Lucent 2008
Sample formula:
CS service drop ratio= Number of CS RAB abnormal releases/Total no. of CS RAB releases * 100%.
VP Call drop ratio= Number of VP RAB abnormal releases/Total no. of VP RAB releases * 100%.
All Rights Reserved © Alcatel-Lucent 2008
Example # 2 ( Retainability)
Due to RF causes ( RL synchronous failure)
Cell W_DL_Delhi_240_10@1 with CSV failure rate of 19% and voice traffic of 0.53 E
Drill down:
All Rights Reserved © Alcatel-Lucent 2008
Mobility
Monitor different kinds of handovers. Soft handover- defining the right neighbors. Missing neighbors, New site turn ups IRAT ( 3G/2G) HO issues. Check 3G/2G neighbor relations- external cell definition
BCCH/BSIC to match with internal cell values. Look for issues in the target 2G cell. Main KPIs: CSV IRAT failure rate, Soft handover success ratio,
AMR soft handover success ratio, PS soft handover success ratio.
All Rights Reserved © Alcatel-Lucent 2008
Sample formula
All Rights Reserved © Alcatel-Lucent 2008
Example # 3 ( mobility) CSV IRAT
Cell ( W_DL_Delhi_351_10@) high IRAT HO failure rate with AMR traffic of 0.25 ErlDrill down:
Iu release from core. Preparation failure. Need to check for resource issues.
All Rights Reserved © Alcatel-Lucent 2008
Coverage
Used for monitoring cell interference status and soft handover gain in a RNC or cluster.
Main KPIs: SHO overhead, UL Interference Cell Ratio SHO overhead -Used to evaluate the consumption of resources
due to soft handover. Trade off between resource consumption and soft handover
benefits. UL Interference cell ratio= (No. of cells with mean RTWP >-98
dbm/ Total No. of Cells). RTWP high/ low? Significance??
All Rights Reserved © Alcatel-Lucent 2008
Sample formula
All Rights Reserved © Alcatel-Lucent 2008
Service Integrity
Indicates the service capabilities for PS/HSDPA throughput on busy hour in each cell and for evaluating the UL BLER values for each cell.
Main KPIs: Average UL Throughput for R99 services. Average DL Throughput for R99 services. HSDPA throughput. HSUPA throughput.
All Rights Reserved © Alcatel-Lucent 2008
PS Counter example
All Rights Reserved © Alcatel-Lucent 2008
CQI
• Channel Quality Index (CQI) is a measure of the quality of DL radio interface measured at the handset ( between 0 and 30)
• The Node B uses this information in the evaluation and assignment of the downlink air interface throughput for the handset every 2ms, the higher the reported CQI, the higher the achievable throughput.
• CQI is not the only factor in the evaluation, however it is the only factor that can be readily improved through optimization.
• CQI is a function of Ec/No.
All Rights Reserved © Alcatel-Lucent 2008
Chandigarh example- CQI
All Rights Reserved © Alcatel-Lucent 2008
Availability
Measures the availability of resources. Main KPIs: Radio Network Unavailability Ratio, Worst Cell Ratio
Formula:
All Rights Reserved © Alcatel-Lucent 2008
Traffic
Used to evaluate the circulated traffic such as CS Erlangs, PS Traffic, Mean UE number for various kind of services.
Key KPIs: No. of CS users, No. of PS R99 users, No. of HSDPA users, No. of HSUPA users, HSDPA traffic volume, HSUPA traffic volume.
Example: CS Equivalent Erlang of RNC VS.CSLoad.Erlang.Equiv.RNC:
This KPI provides the equivalent Erlang values of all the services in the CS domain in the RNC
All Rights Reserved © Alcatel-Lucent 2008
Sample formula
No. of CS users=
(VS.RB.AMR.DL.12.2+VS.RB.AMR.DL.10.2+VS.RB.AMR.DL.7.95+VS.RB.AMR.DL.7.4+VS.RB.AM
R.DL.6.7+VS.RB.AMR.DL.5.9+VS.RB.AMR.DL.5.15+VS.RB.AMR.DL.4.75)
No. of HSDPA users= VS.HSDPA.UE.Mean.Cell,VS.HSDPA.UE.Max.Cell.
HSDPA Traffic volume= VS.HSDPA.MeanChThroughput.TotalBytes
All Rights Reserved © Alcatel-Lucent 2008
Daily 3G NQI report
All Rights Reserved © Alcatel-Lucent 2008
Gsmart Tool Level 2 layout
All Rights Reserved © Alcatel-Lucent 2008
All Rights Reserved © Alcatel-Lucent 2008
All Rights Reserved © Alcatel-Lucent 2008
All Rights Reserved © Alcatel-Lucent 2008
Thank Q