basic dt fundemental

5/21/2018 Basic DT Fundemental

1/20

2G vs3G Comparison EssentialsMultiwireless Sdn Bhd

Prepared by: Huzaini

Basic Fundamental

Course


2/20

BASIC CONCEPT

Multiwireless Sdn Bhd22 May 20102

2G - GSM 3G - WCDMA

Frequency

FDD

Code

CDMA

time

frequency

time

frequency

Time

TDD

Maxis WCDMA frequencies*:f1 10686 (DL) / 9712 (UL) - primary

f2 10637 (DL) / 9687 (UL)f3 10662 (DL) / 9736 (UL)

frequency

structure Network Element:

MSC

SGSN

RNC

NodeB

NodeB

NodeB

iubiuCS

iuPSUE

UEuu

* Note: Different operator have different frequencies and different strategy advice by Vendor (Huawei/Ericsson/NSN)

For CS

For PS

Bandwidth = 5MHzbandwidth

Chip rate = 3.84 Mchip/schip rate

Frame length = 10 msframe

Maxis GSM frequencies:900MHz, 1800MHz

frequency

Bandwidth = 200kHzbandwidth


3/20

SCRAMBLING CODES (SC)

Spreading Factor User DL Bit Rate (kbps) User UL Bit Rate (kbps)

8 384 128

16 128 64

32 64 32

64 32 16

128 16 8

3

SC: 1

SC: 17

Scrambling Code: Using pseudo noise (PN) codes

Used to differentiate cells in the downlink (DL)

Range is 0 - 512

SC

SC: 9, Service: CS Call

DL Channelization code: C128,5

Spreading factor: 128User bit rate: 12.2 kbps

SC: 9, Service: PS Download

DL Channelization code: C8,2Spreading Factor: 8

User bit rate: 384 kbps

Channelization Code: Using Orthogonal Variable Spreading Factor

(OVSF) codes

Fully orthogonal, i.e. do not interfere with

each other

Used to separate different users/cell

Limited codes per cell

Once a code is chosen, any codes on the

same branch above or below the used codecannot be used (refer diagram below)

SF

SC: 418

C8,2C16,3

C32,5

C32,6

C64,9

C64,10

C64,11

C64,11

used

SC: 9



4/20

HANDOVER (1)


2G

Cell1

3GCell1

f1

IRAT

Dedicatedorid

le

(reselection)

Idle(reselection)

3GCell2

f1

SOFT HANDOVERActive Set:Up to 3 cells in soft handover (sHO), i.e. 3 AS. This means

a UE can be served by up to 3 cells at the same time.

Note that 3 AS equals to using 3 cells resources at the

same time.

AS

Things to defineMotorola: inter_rat_enabled, 2g>3g neighbours1

Ericsson: qsi, 2g>3g neighbours

Parameter

2G vs 3G

RxLev = Signal strength = RSCPRxQual = Signal Quality = Ec/Io

BCCH/ARFCN = Frequency Channel / Code = Scrambling Code (SC)

Monitored Neigbour / Detected NeighbourMonitored Neighbour (MN): Neighbour already

defined2, can be added as an AS if criterion is met

Detected Neighbour (DN): Neighbour not defined in the

neighbour list, need to be added TWO-WAY if it is a

valid missing neighbour. A DN whose RSCP is tooclose to the strongest server and not added as a

neighbour will become an interferer.

MN/DN

Add

Dont Add

SOFT HANDOVER

IRAT

Dedicated

TEMS Snapshot

3G

Cell3

f2

HARD

HANDOVER

Dedicated

Inter-freq

uencyHO

Intra-frequency HO

HARD

HAN

DOVER


5/20

HANDOVER(2)

Parameter Meas. Q Eric NSN

e1a Ec/No 3 3

e1b Ec/No 5 6

e1c Ec/No 1 2e1d Ec/No 7.5 4

e2d rscp -104 -102

e2f rscp -101 -97

e3a rscp -95 -100

5

Event 1a -A Primary CPICH entersthe Reporting Range

e1a

Event 1b -A Primary CPICH leavesthe Reporting Range

e1b

Event 1c -A non-active primaryCPICH becomes better than an

Active Primary CPICH

e1c

Event 1d - Change of Best Celle1d

Event 2d - The estimated quality ofthe currently used frequency is

below a certain Threshold

e2d

Event 2f - The estimated quality ofthe currently used frequency is

above a certain threshold

e2f

Event 3a - The Estimated Quality ofthe Currently Used UTRAN

Frequency is below a Certain

Threshold and the Estimated

Quality of the Other System is

above a Certain Threshold

e3a

Maxis default values



6/20

OPTIMIZATION


TEMS Snapshot

RSCP = COVERAGEIt is equivalent to RxLev in GSM

Coverage

Ec/No = QUALITYIt is equivalent to RxQual in GSM. Very important to

optimize network to have good quality (>-12dB)

Quality

OPTIMIZATION CONCEPT To have best Ec/No (not necessarily RSCP) by

minimizing other cells interference. This means

optimizing a cells coverage with balancing between

RSCP and Ec/No.

Ideally, at one point in time, you should have only 1AS

only. But for practicality, it should be less than 3 cells

(including best server) within 6dB of the best servers

RSCP (above example would have 4 cells)

3G Opti METHODS OF OPTIMIZATION Tilting of overshooting site

Power down of overshooting site with max tilts

Neighbour addition of DNs

Reengineering, e.g. antenna swing

Methods

Common Pilot ChannelUse for channel estimation reference at the terminal;

scrambled with cell specific primary SC; DL channel with a

fixed rate of 30 kbps or SF256

CPICH


7/20

RESOURCES & CAPACITY


NODE B

E1 CAPACITYType: Site-level

Note: This resource is for

signaling and traffic between

Node B and RNC (highest priority

among all resources mentioned

here).

Congestion Resolution: E1

upgrade

IUB

CHANNEL ELEMENTType: Site-levelNote: This resource shared between

sectors within one NodeB. It is used to

process different type of services, e.g.

CS, PS, HSDPA, 1 CE = 1 Voice Call

Congestion Resolution: Channel card

activation or addition

CE/CHC

POWERType: Cell-level

Note: Output power on

the downlink is shared

between UEs.for their

respective traffic

Congestion Resolution:

Power upgrade or 2nd

Carrier

POWER

CODEType: Cell-levelNote: This is referring to the

channelization/OVSF code

resource which is one per

service (more codes for

HSDPA)

Congestion Resolution: 2nd

Carrier

CODE

RNC


8/20

RF Tools


TEMS Investigation

NEMO

Genex

Couei

ROMES

Rodge & Schwarz

SwissQual


9/209

Basic Tems Investigation 7.1.3 Overview

What to focus on 3G tems?

Line Chart WCDMA/GSMRadio Parameters WCDMA

Serving/ Active Set-

Neighbours WCDMA

Map

Layer 3

Layer 2

Radio Parameters GSM

Current Channel GSM

Serving Neighbors By

Band GSM


10/201

Line Chart WCDMA/GSM

CPICH RSCP

UM

TS

GS

M

RxLevSub

UE Tx Power/

SIR/ SIR

Target/ Ec/NoRxQualSub

IRAT from UMTS to

GSM network

SQI


11/20

11

Radio Parameters WCDMA

Tx Power- UE

transmit power in

dBm. Valid only in

connected mode.

This window presents a collection of information elements describing the status of the radio link and some

more general radio conditions.

UTRA Carrier RSSI-

Total energy

measured by the

UE in the 5 MHz

frequency band.

SIR-Signal-to-

interference ratio

measured by a UE

on the DPCH.

SQI- Speech Quality Index for

WCDMA. The range is different

depending on the AMR speech

codec mode. The maximum SQIvalues are as follows:

12.2 kbit/s: 30 dBQ

10.2 kbit/s: 28 dBQ

7.95 kbit/s: 28 dBQ

7.40 kbit/s: 27 dBQ

6.70 kbit/s: 27 dBQ

5.90 kbit/s: 24 dBQ

5.15 kbit/s: 21 dBQ

4.75 kbit/s: 19 dBQRSCP

Ec/No

!!RSSI =

!!Target SIR should lower

than SIR- UE will power down


12/2012

Serving/ Active Set- Neighbours WCDMA

Active Set

Monitored

Neighbours

DetectedNeighbours


13/20

13

Layer 3/ Layer 2

Layer 2 messages

Indicate the basic call event.

Example: Call setup, Handover, Dropped Call, Cell Reselection

etc.

Layer 3 messages

Indicates the system information & check the health of the call.


14/2014

Case Studies

1. Voice Call

IRAT

Coverage (Low RF)

Missing Neighbour (Detected Neighbour)/ Overshooting Cell

2G-3G Idle Mode Reselection

3G-2G Idle mode Reselection

2. Video Call

What different between Voice call and Video call?

What is MOC and MTC?

3. Packet Service (PS)

What is PS?

PS vs Car speed during drive test?


15/2015

IRAT

The IRAT threshold:

Base on Ec/No= -12

OR

Base on RSCP= -104 dBm


16/2016

Coverage (Low RF)

Low RF in 3G?

AS/ MN with average RSCP < -100 dBm for

outdoor & with average Ec/No


17/2017

Missing Neighbour (DN)/ Overshooting Cell

DN/ Overshooting Cell?

It will be captured as DN with good RSCP

& Ec/No.

Based on local knowledge, the RF is

needed or it is an overshooting cell.


18/2018


How?

Based on Ec/No threshold.


19/2019


How?

Inter_rat parameterhas to be enabled in 2G

cell.

A few parameters to be changed in 2G

system in order for reselection.


20/20

Video Call

How to differentiate between Voice Call/

Video Call?

DL Spreading Factor= 32 [ DL 64 kbps]

On video call, no IRAT.

Why? It is utilizing the CS64 RAB bearer.

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