02 UMTS Overview

Slide titleIn CAPITALS

50 pt

Slide subtitle 32 pt

UMTS OVERVIEWPraveen Chandrasekaran

Sr Systems Engineer

Top right corner for field-mark, customer or partner logotypes. See Best practice for example.

Slide title 40 pt


Text 24 pt

Bullets level 2-520 pt

Commercial in confidence 2007-01-102

POP Quiz

RSCP

Node BRNC

SC Ec/NoIub

MgW

BLER

Eb/No

IRATUE

RAB


Slide title 40 pt


Text 24 pt



How Does My Network Topology Look Today ?

SGSN

IP BackboneGGSN

SGSNGGSN

Internet

GPRS - Network Baseline

GSM - Network Baseline

BSC

BSC

GSM RAN

BSC

BSC

GSM RAN

TDM BackboneMSC MSC

HLR/AUC


Slide title 40 pt


Text 24 pt



TDM/IP/ATM

How Would this look with WCDMA

SGSN

WCDMA Introduction

BSC

BSC

GSM RAN

BSC

BSC

GSM RAN

MSC MSC

GGSNSGSN

GGSN

Internet

MGw MGw

MSC-S MSC-S

RNC

RNC

WCDMA RAN

RNC

RNC

WCDMA RAN

HLR/AUC


Slide title 40 pt


Text 24 pt



GSM Radio Access Network

Core Network

BSC

BSC

A/Gb

Abis

UmBTS BTS

BTS

MS


Slide title 40 pt


Text 24 pt



WCDMA Radio Access Network

Iu= Iu PS - Gb Iu CS - A

Core NWUTRAN


Slide title 40 pt


Text 24 pt



f

Code

t

MS 1MS 2MS 3

5 MHz

Access Technology Comparison

frequency

Time-Division Multiple Access

TDMA

frequency

Time-Division Multiple Access

TDMA


Slide title 40 pt


Text 24 pt



GSM and WCDMA Comparison

Separate users through different codes

Continuous transmission and reception

Code planning – No Frequency Planning

Variable Cell Radius: Cell Breathing

Radio Link: 1 UE <-> Many Node-B’s

Power is Capacity

Scrambling Code Planning

Soft/Softer Handover

Hard Handover

Orthogonal in time within a cell

Time Slot Synchronization in time

Frequency planning

“Fixed” Cell Radius

Radio Link: 1 MS <-> 1 RBS

# of Frequencies limit capacity

BSIC Planning

Hard Handover

GSM WCDMABTS NodeBBSC RNCMS UE


Slide title 40 pt


Text 24 pt



What is Radio Access Bearer (RAB) ? RAB

– Controlled by the core network (CN)– CN determines traffic class and QoS

– Real-Time Applications Streaming Class: Preserve time relation between

entities (packets) in a data stream Conversational Class: Preserve time relation

between entities within a certain delay– Non-Real Time Applications

Background Class: Destination is not expecting data. Preserve Payload

Interactive Class: Request / Response Pattern with preserved payload


Slide title 40 pt


Text 24 pt



Conversational Speech 12.2 kbps Circuit switched

Conversational CS Data 64 kbps Circuit switched

Streaming 128/128 PS

Interactive Variable rate Packet switched

Multi-RABCombination of Conversational Speech and Interactive 64/64

RAB Examples


Slide title 40 pt


Text 24 pt



RAB Attributes

• Transfer delay

RAB Service Attributes

• Traffic Class

• Maximum bit rate [kbps]

• Delivery order

• Maximum SDU size

• SDU format information

• SDU error ratio

• Residual bit error ratio

• Delivery of erroneous SDUs

• Guaranteed bit rate

• Traffic handling priority

• Allocation/retention priority

• Source statistics descriptor

• Relocation requirement•RAB asymmetry indicator

RAB

UE RBS RNC CN


Slide title 40 pt


Text 24 pt



What is High Speed Downlink Packet Access (HSDPA)

STANDARDIZED Integral part of WCDMA (3GPP Release 5)

REDUCED DELAY Reduced round trip time

CAPACITY 2 – 3 times improved system throughput

SPEED Higher bit rates: up to 14 Mbps

Smooth Upgrade Short time to market with existing sites


Slide title 40 pt


Text 24 pt



Future proof WCDMA RAN

2004 2005 2006 2007

MBMSWCDMA MIMO2x2

HSDPAPhase 2

HSDPAPhase 1

2008

Enhanced ULPhase 1

Enhanced ULPhase 2

Latency (ms)

14

1.8

~50

28

5.8

~30

14

5.8

~30

3.6

0.384

~75

0.384

0.064

~150

UL Mbps

DL Mbps

LTE20 MHz

2009

100

50

~10

Continuous improvement of data capabilities, also after HSPA


Slide title 40 pt


Text 24 pt



HSDPA Basic Principles

Shared Channel TransmissionDynamically shared in time & code

domain

Higher-order Modulation16QAM in complement to QPSK for

higher peak bit rates

2 ms

Short TTI (2 ms)Reduced round trip delay

Fast Hybrid ARQ with Soft Combining

Reduced round trip delay

Fast Radio Channel Dependent Scheduling

Scheduling of users on 2 ms time basis

Fast Link AdaptationData rate adapted to radio

conditions on 2 ms time basis

t

P

Dynamic Power AllocationEfficient power &

spectrum utilisation

Slide titleIn CAPITALS

50 pt


RF OVERVIEW


Slide title 40 pt


Text 24 pt



Outline Pilot Coverage Capacity Cell Breathing Concepts Radio Network Design Strategies

– Securing coverage– Achieving confined cells– Selecting strategic sites– Code planning– Power planning– Neighbour planning– Micro-Cell Design Considerations

Combining GSM and WCDMA– Using IRAT to enhance service area


Slide title 40 pt


Text 24 pt



What is Coverage in WCDMA Signal does not mean “Coverage” in WCDMA

Pilot Signal - RSCPPilot Ec/NoService Coverage

Pilot RSCPPilot Ec/No


Slide title 40 pt


Text 24 pt



Eb/No and Sensitivity

The required Erequired Ebb/N/N00 is the minimum ratio to achieve a given QoS (BER or BLER) for a specific service.

The RBS sensitivityRBS sensitivity is the required minimum signal level at the reference point that satisfies the Eb/N0 requirement of the related service.

NNff is the effective noise figure at reference point.

PGNoEb

NoEc

IC

reqbfthrefsens NENNRBS 0, PG -


Slide title 40 pt


Text 24 pt



Properties of WCDMA Link BudgetProcessing Gain - Downlink receiver sensitivity

Thermal noise = - 108 [email protected] MHz

Pro

cesi

ng g

ain

UE Noise Figure

Eb/No

Sensitivity – minimum code powerrequired

-110 dBm

-120 dBm

-130 dBm

Speech

Packet 64

Packet 128

Packet 384GSM Speech

(Thermal noise – Process Gain)

Sensitivity = Pthm – 10log(Rchip/Rinfo) + Nf + Eb/No

Processing Gain = Rchip/Rinfo

Speech

PS 64

CS 64PS 384

Plan for a service


Slide title 40 pt


Text 24 pt



Properties of WCDMA Link BudgetShared power resources in downlink

Mobiles share the available power in the cell

The power usage depends on– Distance to cell– Radio environment– Interference– Service type

High power usage far from cell or with high data rate service

Low power usage close to site in good radio condition

Sensitivity levels are different for different services Different services will have different coverage levels

Link budgets for the RABs consider coverage as well as capacity.


Slide title 40 pt


Text 24 pt



PRx

UL sensitivity

Properties of WCDMA Link Budget Noise rise - single cell

-110 dBm

-120 dBm

-130 dBm

WCDMA ULPint,own

Own cell interference

Each new user decreases the cell size – cell “breathes” with load


Slide title 40 pt


Text 24 pt



PRx

UL sensitivity

Properties of WCDMA Link Budget Noise rise - multi cell

-110 dBm

-120 dBm

-130 dBm

WCDMA ULPint,own

Own cell interference

Pinter,othe

r

Other cell cell interference

The anticipated load must be taken into account in the cell planning process


Slide title 40 pt


Text 24 pt



Capacity Considerations Effect of different user distribution

High power usageLow capacity

Low power usageHigh code usage

Code limited scenario

Power limited scenario


Slide title 40 pt


Text 24 pt



Radio Network Design Strategies

Inputs Securing coverage Achieving confined cells Selecting strategic sites Parameter planning Using IRAT Indoor and microcells


Slide title 40 pt


Text 24 pt



Securing Coverage

High gain antennas (15-18 dBi)

Use TMAs– Indoor coverage– With Enhanced UL this

will be even more important

Plan for network load Consider service coverage

15 dBi 18 dBi

CPICH RSCP

CPICH Ec/Io

Service Coverage

Design is built up by considering the basics first.


Slide title 40 pt


Text 24 pt



Designing for LoadRAB Coverage

Unloaded

RAB Coverage High Load

Coverage shrinks with load due to cell breathing.

Coverage and capacity evaluation should be performed early in the design.

Capacity per sector is specified, then coverage is evaluated under corresponding load.

Coverage and capacity can be traded off.

– Large coverage footprint, low capacity.

– Smaller coverage footprint, high capacity.


Slide title 40 pt


Text 24 pt



Service CoverageAMR 12.2k

Voice

PS 64k I/B

Coverage footprint for all services (RABs) will not match.

Specify coverage target for a particular service under particular load.

Speech

PS 64

CS 64PS 384

Plan for a service


Slide title 40 pt


Text 24 pt



Controlling Interference – Confining Cells Electrical Antenna tilt. Use RET.

– For efficient capacity tuning.

High Gain antennas (small vertical BW).

– To achieve maximum benefit of tilt.

Separate antenna systems recommended.

– GSM and UMTS may require different tilt.

0%2%4%6%8%

10%12%14%16%18%20%

0 1 2 3 4 5 6 7Tilt

Cap

acity

gai

n

Example of capacity gain vs tilt

Ideal capacity when –3 dB point at cell border


Slide title 40 pt


Text 24 pt



Selecting Strategic Sites Avoid boomers

– Harder to confine coverage.– Generate interference far

away from service area.

High sites generate interference outside the planned coverage area

Placing sites close to traffic ensures high capacity

Place sites close to traffic

– Ensures high air interface capacity

Sectorize Omni sites


Slide title 40 pt


Text 24 pt



Scrambling Codes (Also called PN, long or gold codes)

SC3 SC4

SC5 SC6

SC1 SC1

Cell “1” transmits using SC1

SC2 SC2

Cell “2” transmits using SC2

Downlink: Scrambling Code used to distinguish each cell (assigned by operator – SC planning)

Uplink: Scrambling Code used to distinguish each UE (assigned by network)


Slide title 40 pt


Text 24 pt



Handovers

Soft/Softer handover– HO between cells using same UMTS carrier

frequency

IRAT handover/Cell change– HO/cell changes between UMTS and GSM

Inter-frequency handover– HO between different UMTS carrier frequencies


Slide title 40 pt


Text 24 pt



Concept of Soft/Softer Handover

Cell A

Cell B

Cell C

Single Link

The UE measured the CPICH Signal strenght (RSCP) and quality (Ec/No) to determine which cell to add in the active set

Add and remove from active set is based on relative measurments

Softer handover-two cells within the same RBS in Active Set

Soft handover-two cells from different RBS in Active Set

Soft/Softer handover-three cells in Active Set


Slide title 40 pt


Text 24 pt



Parameter Planning - Neighbors

Good neighbor planning is essential

Typically more neighbors per cell in UMTS– Neighbor Set

Maximum = 32 Typical = 20

– Active Set Maximum = 4 Typical = 3


Slide title 40 pt


Text 24 pt



WCDMA Coverage GSM CoverageRoad

Using the WCDMA Frequency

Using the GSM Frequency

Inter RAT Handover

Inter Radio Access Technology (IRAT) handover


Slide title 40 pt


Text 24 pt



Planning IRAT – What are the Options ? IRAT everywhere during initial

deployment– Allows immediate service coverage

IRAT in mature networks– IRAT handover allowed only in

border areas or selected sites

GSM network

WCDMA


Slide title 40 pt


Text 24 pt



IRAT Strategies If GSM has better coverage it can be advantageous to terminate the

call (speech) in GSM. (Operator Defined Strategy)– In order to minimize handover.

This can be achieved by:– Not allowing GSMUMTS.– Only allow handover when there is significant load in GSM.

Strategy only possible for CS services.– PS services use cell reselection mechanism moves to 3G where

possible. Packet handovers to GPRS/EDGE result in degradation of user

experience.


Slide title 40 pt


Text 24 pt



Micro-Cells Design Considerations

Smaller coverage area close to site

Large coverage area

Higher interference limits coverage area close to site

Primary application for micro is hotspot areas.

– Essential to place site close to traffic.

Micro cell coverage area depends on distance to macro base station.


Slide title 40 pt


Text 24 pt



High load

Cell breathing

Low loadHigh load

Cell breathing

Low load

Cell reduction due to capacity load.

The Indoor solution will provide up to 4 times the capacity in the macro cell network! Penetrating buildings with outdoor cells is wasteful of resources for high-rate WCDMA users since high power is needed.

Network Design – Indoor Coverage


Slide title 40 pt


Text 24 pt



Consider all aspects (technical and business) as design inputs

Different RABs have different service coverage

Load impacts Service coverage area (Cell Breathing)

Secure coverage and contain interference

Indoor coverage design considerations

IRAT Strategies

Conclusions


Slide title 40 pt


Text 24 pt



02 UMTS Overview

Documents

preserve time

active set

cell interference

scrambling

reference

cell breathing

wcdma ul

wcdma ran