Download - Alcatel WCDMA KPI Evaluation 3G WCDMA

Krishna K Jayachandran

KPI evaluation 3G WCDMA

All Rights Reserved © Alcatel-Lucent 2008

Source: Huawei


KPI Structure


CS Call set up diagram

Source: T Mobile documentation ( Public)


PS Call set up diagram

Source: T Mobile documentation ( Public)


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


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


Sample formula


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.


Example # 1 ( Accessibility)

Alarm: System dynamic traffic exceeding licensed limit


Remedial action

Congestion- EDT/MDT, CPICH ( only when absolutely necessary) for power, addition of HW for codes, checking SW licenses for Channel elements.


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.


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


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%.


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:


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.


Sample formula


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.


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??


Sample formula


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.


PS Counter example


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.


Chandigarh example- CQI


Availability

Measures the availability of resources. Main KPIs: Radio Network Unavailability Ratio, Worst Cell Ratio

Formula:


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


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


Daily 3G NQI report


Gsmart Tool Level 2 layout


Thank Q

Download - Alcatel WCDMA KPI Evaluation 3G WCDMA

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