Drive Test Analysis

(1)

Mobile

Comm

Technologies India Pvt. Ltd.

Dallas

.

Atlanta Atlanta

.

Washington Washington

.

LA LA

.

Sao PauloSao Paulo

.

New Delhi New Delhi

.

TorontoToronto

.

Muscat Muscat

.

SydneySydney

Drive T

(2)

MobileCommComm is is committed to providing our customers with quality instructor ledcommitted to providing our customers with quality instructor led Telecommunications Training.

Telecommunications Training.

This documentation is protected by copyright. No part of

This documentation is protected by copyright. No part of the contents of thisthe contents of this documentation may be reproduced in any form, or

documentation may be reproduced in any form, or by any means, without the prior by any means, without the prior written consent ofwritten consent of Mobile

MobileCommComm Technologies .Technologies .

Document Number: RK/CT/3/2010 Document Number: RK/CT/3/2010 This manual prepared by: Mobile

This manual prepared by: MobileCommComm TechnologiesTechnologies

MobileComm Technologies

MobileComm Technologies(India)Pvt. (India)Pvt. Ltd.Ltd. 424, First Floor, Udyog Vihar Phase -4, 424, First Floor, Udyog Vihar Phase -4,

Gurgaon-122002 Gurgaon-122002 Headquarter: Headquarter:

MobileComm Professionals Inc. MobileComm Professionals Inc. 1255 West 15th Street, Suite 440 1255 West 15th Street, Suite 440 Plano, TX, 75075 Plano, TX, 75075 Tel: (972) 633-5100 Tel: (972) 633-5100 Fax: (972) 633-5106 Fax: (972) 633-5106

www.mcpsinc.com

(3)

MobileCommComm is is committed to providing our customers with quality instructor ledcommitted to providing our customers with quality instructor led Telecommunications Training.

Telecommunications Training.

This documentation is protected by copyright. No part of

This documentation is protected by copyright. No part of the contents of thisthe contents of this documentation may be reproduced in any form, or

documentation may be reproduced in any form, or by any means, without the prior by any means, without the prior written consent ofwritten consent of Mobile

MobileCommComm Technologies .Technologies .

Document Number: RK/CT/3/2010 Document Number: RK/CT/3/2010 This manual prepared by: Mobile

This manual prepared by: MobileCommComm TechnologiesTechnologies

MobileComm Technologies

MobileComm Technologies(India)Pvt. (India)Pvt. Ltd.Ltd. 424, First Floor, Udyog Vihar Phase -4, 424, First Floor, Udyog Vihar Phase -4,

Gurgaon-122002 Gurgaon-122002 Headquarter: Headquarter:

MobileComm Professionals Inc. MobileComm Professionals Inc. 1255 West 15th Street, Suite 440 1255 West 15th Street, Suite 440 Plano, TX, 75075 Plano, TX, 75075 Tel: (972) 633-5100 Tel: (972) 633-5100 Fax: (972) 633-5106 Fax: (972) 633-5106

www.mcpsinc.com

(4)

UMTS Call Flow

3

(5)

Soft/Softer

Handover/Clear

Call to a MS

Paging

Call from a MS

RRC

Connection

RAB

Assignment

Supervision

on on PICH/ PICH/ SCCPCH SCCPCH on FACH/ on FACH/ SCCPCH

SCCPCH

Predefined Signaling

RAB Selected

on FACH/ on FACH/ SCCPCH SCCPCH on on DPDCH DPDCH

Assignment of DPDCH

on on RACH RACH

Activate

Algorithms

Power Ctrl.

Code Ctrl.

Admission Ctr

l.

RAB Selection RAB Selection MEASUREMENTS MEASUREMENTS •

•Directed RetryDirected Retry

•

•Load SharingLoad Sharing

Soft Handover

•

•Inter cell/BSCInter cell/BSC

•

•Intra cell/BSCIntra cell/BSC

•

•OL/ULOL/UL

•

•Bad QualityBad Quality

• •UrgencyUrgency HCS HCS

I

n

e

r

L

o

p

/

O

u

t

e

r

L

o

p

P

o

w

e

r

C

o

n

t

r

o

l

(RRC Connect. Perform.) (RRC Connect. Perform.) (Random Access) (Random Access)

(RAB Establish. Fail.) (RAB Establish. Fail.)

(Traffic Erlangs) (Traffic Erlangs) (Call Quality) (Call Quality) (Handover Perf.) (Handover Perf.) (Dropped Calls) (Dropped Calls) (Available TCH) (Available TCH) (Paging Perf.) (Paging Perf.)

UMTS Call Flow

Open Loop Open Loop Power Control Power Control (Throughput) (Throughput)

4

(6)

UMTS Call Flow

(7)

•

_{TEMS Investigation for WCDMA (Software)}

•

_{TEMS Scanner (Software + HW)}

•

_{External GPS}

•

_{User Equipment (UE)}

•

_{TEMS DeskCat for post processing}

•

_{MCOM3g/Mapinfo/MIPT}

•

_{MS Access/Excel based tools}

Tools For Tuning/Optimization & Data Post Processing

Active measurement needed due to lack of statistics

(8)

(9)

(10)

(11)

(12)

(13)

(14)

USB2 USB1

Com 1

scanner

Short call Long Call

USB1 CS64

GPS

USB1 PS

Drive Test Equipments for Voice, CS64 & PS call

(15)

(16)

The basic measurements of scanner are

•

_{CPICH_RSCP (received signal code power)}

•

_{CPICH_Ec/No (received energy per chip divided by the power density in the}

band)

•

_{RSSI (received signal strength indicator)}

What can you achieve with scanner?

•

_{Crossed feeder issues (DL)}

•

_{Coverage verification}

•

_{Interference problems (overshooting cell, pilot pollution)}

•

_{Missing neighbours}

(17)

COVERAGE VERIFICATION - Primary Common

Pilot Channel

Verify P-CPICH detection to minimize coverage holes

• P-CPICH RSCP

• P-CPICH Ec/No

Coverage level RSCP _[dBm] E

c /N 0 [dB]

Sufficient

RSCP

_{ }

₁₀₀

E

c

/N

0  

14 Poor



115



RSCP

<



100



16



E

c

/N

0

<



14 No coverage

RSCP

_<

_

₁₁₅

E

(18)

•

_{Yellow is good}

•

_{Blue can generate}

problems

•

_{Grey is bad}

(19)

•

_{Green is good}

•

_{Blue can}

generate

problems

•

_{Orange is bad}

(20)

INTERFERNECE

-100 -90 -80 -70 -60 -50 -40 -30 -25 -20 -15 -10 -5 0 5 Ec/Io [dB] R S C P [ d B m ] High interference

By correlating low Ec/No with high RSCP, areas with high

interference can be detected

(21)

(22)

Primary Common Pilot Channel (P-CPICH)

_–

OVERSHOOTING

(23)

OVERSHOOTING

(24)

Primary Common Pilot Channel (P-CPICH)

_–

PILOT POLLUTION

• P-CPICH RSCP

• P-CPICH Ec/No

High CPICH reception levels from many

Cells, (more than MAX_ACTIVE_SET)

size serving c c

_threshold

_AS

N

E

N

E

count

Pilot

(





)



0 0

(25)

(26)

(27)

PILOT POLLUTION

Change Proposals

Site

Name

Sector

Number

SC of

Pilot

Height of

Antenna

(meters)

Antenna

Tilts

(degree)

Proposed

Antenna

Tilts

(degree)

A

1

173

38

2

5 A

2

76

38

2

4 D

1

485

47.3

2

8 C

2

24

39.2

3

5 B

3

79

27

2

3

(28)

0 5 10 15 20 25 30 35 Numbers of Samples 173 76 485 79 24 SC of Pilots 0 5 10 15 20 25 30 35 40 Number of Samples 173 76 79 24 SC of Pilots

PILOT POLLUTION

Initial Drive Test (before tuning)

(29)

UE TUNING

•

_{Voice /Video/PS calls}

–

_{Long calls}

–

_{short calls}

•

_{Identify problem areas}

–

_{Blocked calls}

–

_{Dropped calls}

(30)

Short Calls Analysis

Set-up a call and maintain it for a pre-defined time duration

(for 15-60 s)

Call set-up failure and drops during short calls can be mainly

used to analysis Accessibility failure due to:

•

_{UE Failure}

•

_{Unsuitable Parameters Setting}

•

_{Coverage Problem}

•

_Interference

(31)

Long Calls Analysis

Drops during long call can be used to identify:

•

_{Missing Neighbor Relation}

•

_{Coverage Problem}

•

_{UE Problems}

•

_{Network Characteristics}

•

_{Best Parameter Setting}

•

_Others

Set-up a call and maintain it until it is drop (used for

the analysis of Retainability performace)

(32)

KEY PERFORMANCE INDICATORS

Accessability (Call set-up success rate)

Retainability (Dropped calls)

Mobility (Handover success rate)

Integrity (BLER and throughput)

(33)

Case 1: Drop due to missing neighbor

Problem: Detected Nighbor (DN)

•

_{UE sends a Measurement Report that contains an event1a means adding a}

new RL (cell) to Active Set

•

_{If the reported cell is not in the current neighbor cell list and the reported}

Ec/No is better than the best serving cell Ec/No in AS by some dBs (set by a

RNC parameter)

(34)

Case 1: Drop due to missing neighbor

“DN” cell better than the serving cell

DL BLER gets worse

“DN” cell better than the serving cell

(35)

Case 2: Drop due to Poor Coverage (low RSCP)

Problem: Poor DL coverage

When UE gets to an area with low RSCP ( < -105 dBm)

regardless Ec/No values there is high risk for drop.

UE will likely ramp up the transmitted power and reach its

max power. The DL BLER will probably increase and SIR

target cannot maintain anymore, finally the call drops.

(36)

Case 2: Drop due to DL Poor Coverage

Very bad RSCP

UE max Tx power

and

high DL BLER

Very bad RSCP

UE max Tx power

and

high DL BLER

(37)

Case 3:

PS: Session Error due to Poor DL Coverage

UE enters a very low coverage area (RSCP <

–

_{105 dBm).}

The packet connection is carried on a 64/64 DCH Channel

as consequence of the low coverage conditions.

The UE will likely ramp up its power to the maximum, goes

to Idle Mode and the Application and RLC throughputs go

to zero.

At this point the RAS application will start the Session

Timeout timer, if the throughput is not resumed the Session

(38)

PS: Session Error due to Poor DL Coverage

App throughput ~64kbps

Very low RSCP

App throughput ~64kbps

(39)

FINAL WORDS

• _{For network tuning, we need to relay on field measurements which require extensive}

drive tests

• _{Finding the best possible configuration for antenna heights, tilts, azimuths and}

parameter setting for all the present cells/sectors in the network and also for any new sites that might be needed to improve coverage

• _{Power adjustment can also be used for network tuning but can become complicated and}

result in poor network performance

• _{Use of Remote Electrical Tilt (RET) Antenna is preferred over mechanical tilt antenna} • _{Neighbour definition is of prime importance in UMTS network (Soft handover gain and}

interference reduction). Keep neighbour list upto 20.

• _{Automated tools are needed that could suggest the best possible neighbour relations,}

antenna heights and tilts by using both the field measurements and the propagation models & simulations

• _{Skilled people, right methods and advanced tools are needed to perform 3G tuning and}