Contents

1) Introduction

2) Main KPI’s

3) SDCCH congestion

4) TCH congestion

5) CSSR

6) HOSR

7) CDR

8) Useful information

Introduction

Firstly, we must differentiate between 4 words:

Counter KPI

Parameter Algorithm

1) Counter:

It is the counters in the BSC that counts every

event in the layer 3 messages.

Such as : K3012B Call Drops in TCH Handovers (Traffic Channel),

(ET02) TCH CDR Per Cell & K3016:Configured TCHs

Introduction

2) KPI:

It is the combination of some counters in a

certain formula to help in judging the network

performance .

Such as: CDR, HOSR & TCH congestion

Introduction

3) Parameter:

It is the item in the BSC to be adjusted to have a

switch, threshold or an interval

Such as: CRO, Concentric circles HO allowed & UtoO traffic HO

allowed.

Introduction

4) Algorithm:

It is a group of commands controlling a certain

process.

Such as: HO algorithm, Power control algorithm & Direct retry

algorithm.

Introduction

To judge a network we have 5 main KPI’s:

Main KPI’s

SDCCH congestion TCH congestion CSSR

HOSR CDR

SDCCH Congestion

1) SDCCH congestion:

SDCCH congestion

Total No. of SDCCH assignment failures(Due to congestion)

Total No. of SDCCH requests

SDCCH congestion may be due to:

No. of required SDCCHs > Configured SDCCHSA) Capacity

B) Availability No. of Available SDCCHs ≠ Configured SDCCHS

SDCCH congestion

Incase of Capacity problem & TCH congestion=0 the solution will be:

Expansion(Static or Dynamic SDCCH)

Load sharing

Static SD: Traffic in BH > Available capacity

Dynamic SD: Congestion is due to sudden increase in SD requests

Sharing the load with neighboring cells using both CRO & PBGT parameters

SDCCH congestion

Incase of Capacity problem & TCH congestion≠0 the solution will be:

Expansion

Load sharing

Enabling Dynamic SDCCH if TCH & SD congestion are not in the same time

Physical expansion is needed if TCH & SD congestion are in the same time

Sharing the load with neighboring cells using both CRO & PBGT parameters

SDCCH congestion

Incase of availability :

Checking alarms on the cell

Checking alarms on neighboring cells

SDCCH congestion

TCH Congestion

TCH congestion

No. of TCH assignment failures due to congestion(Stable state + HO)

No. of TCH assignment requests(Stable state + HO)

TCH congestion

SDCCH congestion may be due to:

No. of required TCHs > Configured TCHSA) Capacity

B) Availability No. of Available TCHs ≠ Configured TCHS

TCH congestion

Incase of Capacity problem the solution will be:

Expansion(Static or Dynamic SDCCH)

Load sharing

Enabling HR

Remove useless SDs & Packet TSs

Add new TRX

Idle mode: CRO & Direct Retry(DR)

Dedicated mode: Incoming & outgoing PBGT HO & load HO

TCH congestion

Incase of availability :

Checking alarms on the cell

With sudden increase in traffic then check alarms on neighboring cells

Available = Configured

Available ≠ Configured

CSSR

CSSR

Total No. of TCH assignment failures

Total No. of TCH assignment requests1 - ( )

Total No. of SDCCH failures

Total No. of SDCCH requests1 - ( )×

× (1 - SDCCH call drop)

CSSR

For TCH assignment failure, it includes:

1) Radio problems

2) BSS problems

3) Congestion problems

CSSR

For SD drop rate, it is affected by:

1) Poor coverage

2) UL-DL imbalance

3) High Interference (Internal or External)

4) Cross connection

For SD congestion, it was discussed in the previous slides

HOSR

HOSR

Total No. of successful HOs(Incoming + Outgoing + Intracell)

Total No. of HO requests(Incoming + Outgoing + Intracell)

HOSR

HO purposes:

Mobility

Save MS & BTS power

Sustain calls

HOSR

We may classify HOs according to:

Network Architecture

Intra BSC:• Intra-cell• Inter-cell• Intra-site• Inter-site

Synchronization

• Synchronous•Asynchronous

Radio

• Normal (Better cell/PBGT)• Emergency (BQ/Edge/TA/ Interference/Sudden level drop)• Performance (Load/Layer/ Level/ Fast moving)•Concentric (UtoO/OtoU)

HOSR

For PBGT HO:

Max of (PBGT HO threshold, PBGT HO hystersis)

RxLevel (serving)

RxLevel (neighbour)

≥ +

For BQ HO:

PBGT HO threshold

RxLevel (serving)

RxLevel (neighbour)

≥ + BQ HO threshold

-

For Interference HO:

RxLevel thresholdRxLevel (serving) ≥BQ thresholdQuality (serving) ≥

Interference HO has lower priority than BQ HO because there is no condition on the target cell level

HOSR

For Layer HO:

HystersisLayer HOthreshold

RxLevel (Higher priority)

≥ +

•This level is the min. level required for the higher priority cell to trigger layer HO

•There is no PBGT HO between 2 cells in different layers

•Entering higher layer cell is by layer HO & exiting is by Edge HO

(4) Umbrella

(3) Macro

(2) Micro

(1) Pico

For Edge HO:

If UL Edge HO RxLevel threshold OR DL Edge HO RxLevel threshold is satisfied

HOSR

For Load HO:

If Load HO threshold on source AND Load HO threshold on target cells are satisfied

For TA HO:

TA HO thresholdTA (serving) ≥

It is the logical way to overcome overshooting

HOSR

For MS fast moving HO:

It is done by increasing the ranking of higher layer & prevent HO to lower layer

For Sudden power drop HO:

It is done in the BSC by comparing values of successive measurement reports.

It is disabled in Huawei network

For Level HO:

It is disabled in Huawei network

HOSR

HO Algorithm:

MR

MR preprocessing

Penalty application

Basic ranking (16-Bit)

HO decision

HOSR

HO Priorities:

TA H

O

BQ

HO

Sud

den

R

xLev

el d

rop

H

O

Inte

rfer

ence

H

O

Load

HO

Edge

HO

Laye

r/Le

vel

HO

PB

GT

HO

Con

cen

tric

HO

MS

fast

mov

ing

HO

1 2 3 54 76 8 9 10

HOSR

To Analyze HOSR it is divided to:

Intra cell HO failures

Outgoing HO failures

Incoming HO failures

HOSR

Intracell HO failures may be

OtoU

•Congestion on underlaid•Underlaid Interference•Alarms•Faulty EGSM TRXs or DDPUs•Path Imbalance

UtoO

•Congestion on overlaid•Faulty DCS TRXs or DDPUs•Path Imbalance•Alarms•Wrong DCS electric tilt

HOSR

Incoming HO failures may be due to

Congestion

Failed TCH seizures due to busy TCHs ≈ Failed Incoming HO failures

Radio

• External Interference• Internal Interference•Configuration problem

BSS

• Alarms• Faulty TRXs or combiners

• Path imbalance

Outgoing HO failures may be due to

To one cell

Problem in the neighbour cell

To all cells

Revise counters requests

HOSR

HOSR

To analysze outgoing HO requests:

1) Quality requests >>> Level requests

UL Quality requests >>> DL Quality requests External

Interference

DL Quality requests >>> UL Quality requests Internal

Interference

2) Strenth requests >>> Remaining counters

Path Imbalance (UL limited)UL Strenth requests >>> Remaining counters

DL Strenth requests >>> Remaining countersPath Imbalance (DL limited) or

HW problem

HOSR

3) UL, DL quality & strenth requests >>> PBGT requests

Poor coverage area

Ideally, the majority of requests must be PBGT requests

CDR

CDR

Total No. of dropped calls (Stable state + HO)

No. of successful TCH assignments (Stable state + HO)

CDR

Call drops may be due to

Error indication

Incase of bad radio conditions if the BTS does not receive the correct frame & T200 timer expired N200+1 times the call drops

Release Indication

The MS send a disconnection message to the BTS

Connection Failure

Incase MS does not decode SACCH or the BTS does not decode MR until RLT expires(=32 in DL & 24 in UL) the call drops

CDR

Call drop reasons:

1) Poor coverage

2) Interference

3) Missing neighbors

4) Outgoing HO failures

5) Congestion on underlaid

6) Overshooting

7) Path imbalance

8) Configuration problems

9) Alarms

Thank You