Chapter 1_ 3G Technology Funamentals

Copyright All rights reserved TA -TC 6250 E01TECHCOM Consulting

Content

3G Technology Fundamentals

Parameter Optimization Overview

3G Optimization Technique

Drive Test Post Processing & issue Analysis

3G Drive-test and Optimization


Content

WCDMA Basic Theory

Radio Resource Management

HSPA Overview

3G Technology Fundamental

Copyright All rights reserved TA -TC 6120 01/2005TECHCOM ConsultingCopyright All rights reserved TA -TC 6250 E01TECHCOM Consulting

TECHCOM ConsultingUMTS Air interface is built based on two technological

solutions:

1. WCDMA- FDD

2. WCDMA- TDD

WCDMA FDD is more widely used solution

FDD: Separate UL & DL Frequency band

WCDMA TDD technology is used in limited number of

Networks

TDD: UL & DL separated by time, utilizing

same frequency

Both technologies have own dedicated frequency bands.

This Course concentrate on design principles of WCDMA-

FDD solution.

WCDMA Basic Theory

UMTS FDD

Uplink 1920MHz-1980MHzDownlink 2110MHz-2170MHz


WCDMA Modes


TECHCOM ConsultingMultiple access technology is Wideband

CDMA (WCDMA):

All cells at same carrier frequency

Spreading Codes used to separate cells and

users

Signal Bandwidth 3.84MHz

Multiple Carrier can be used to increase the

capacity:

Inter-Frequency functionality to support mobility

between frequencies

Compatibility with GSM Technology:

Inter-System Functionality to support mobility

between GSM and UMTS

WCDMA FDD Technology


WCDMA FDD frame Structure

f

t

Middlepoint ofWCDMA carrier

WCDMA frame 10 ms

15 slots, each of them 2/3 ms


Differences between WCDMA & GSM

WCDMA GSM

Carrier spacing 5 MHz 200 kHz

Frequency reuse factor 1 118

Power controlfrequency

1500 Hz 2 Hz or lower

Quality control Radio resourcemanagement algorithms

Network planning(frequency planning)

Frequency diversity 5 MHz bandwidth givesmultipath diversity with

Rake receiver

Frequency hopping

Packet data Load-based packetscheduling

Timeslot basedscheduling with GPRS

Downlink transmitdiversity

Supported forimproving downlink

capacity

Not supported by thestandard, but can be

applied


UMTS & GSM Network Planning

GSM900/1800: 3G (WCDMA):


WCDMA basic Theory

FrequencyBand

SpreadingFactor

Power

WCDMAOriginating Bit Received Bit


Transmission Power

Frequency

5MHz

Power density

Time

High bit rate user

Low bit rate user

Capacity/Interference/Load/Power


WCDMA Technology

5 MHz

3.84 MHz

f

5+5 MHz in FDD mode5 MHz in TDD mode

Fre

qu

ency

TimeDirect Sequence (DS) CDMA

WCDMA Carrier

WCDMA

5 MHz, 1 carrier

TDMA (GSM)

5 MHz, 25 carriers

Users share same time and frequency


CDMA Principle- Chip, Bits & Symbol

Spreading Code

Spread Signal

Data

Air Interface

Bits (In this drawing, 1 bit = 8 Chips SF=8)

Baseband Data

-1

+1

+1

+1

+1

+1

-1

-1

-1

-1

ChipChip


Spreading Principle

Direct Sequence Spreading - Code Division Multiple Access (DS-CDMA)

Separates users through different codes Codes are used for two purposes:

Differentiate channels/users Spreading the data over the entire bandwidth

f

Code

t

MS 1

MS 2

MS 3

5 MHz

WCDMA (5 MHz)

IS-95 (1.25 MHz)

CDMA2000 (1.25, 3.75 MHz)


TECHCOM Consulting

Spreading code = Scrambling code + Channelization

code

Scrambling codes (Repeat period 10 ms=38400 chips)

Separates different mobiles (in uplink)

Separates different cells (in downlink)

Channelization codes

Separates different channels that are transmitted on the

same scrambling code

Orthogonal Variable Spreading Factor (OVSF) codes

Period depends on data rate

512 DL Primary SCs: separates cells in same carrier frequency

16.7 million UL SCs: separates users

Spreading Principle


Scrambling and Channelization Codes


DL Spreading and Multiplexing in WCDMA

User 3

User 2

User 1

BCCH

Pilot X

CODE 1

X

CODE 2

X

CODE 3

X

CODE 4

X

CODE 5

+

X

SCRAMBLING

CODE

RF

SUM

User 2

User 1

BCCH

Pilot

Radio frame = 15 time slots

Time

User 3

3.84 MHz

RF carrier

3.84 MHz bandwidth

CHANNELISATION codes:


TECHCOM ConsultingWalsh-Hadamard codes: orthogonal variable spreading

factor codes (OVSF codes)

SF for the DL transmission in FDD mode = {4, 8, 16,

32, 64, 128, 256, 512}

SF for the UL transmission in FDD mode = {4, 8, 16,

32, 64, 128, 256}

Good orthogonality properties: cross correlation

value for each code pair in the code set equals 0

In theoretical environment users of one cell do not

interfere each other in DL

In practical multipath environment orthogonality is

partly lost Interference between users of same cell

DL & UL Channelization Codes

Orthogonal codes are suited for channel separation,

where synchronisation between different channels

can be guaranteed

Downlink channels under one cell

Uplink channels from a single user

Orthogonal codes have bad auto correlation

properties and thus not suited in an asynchronous

environment

Scrambling code required to separate signals between

cells in DL and users in UL


Channelisation Code Tree

Spreading Factors in a subtree

Channelization Codes (CCn,m) = Orthogonal variable SF Codes OVSF (for UL & DL)

CC1,0 = (1)

CC2,1 = (1,-1)

CC2,0 = (1,1)

CC4,0 = (1,1,1,1)

CC4,1 = (1,1,-1,-1)

CC4,2 = (1,-1,1,-1)

CC4,3 = (1,-1,-1,1)

CC256,0CC256,1CC256,2

CC256,255

CC256,254

SF = 1 SF = 2 SF = 4 SF = 256

CC1 = (1) CC2 =1 1

1 -1CCn =

CCn/2 CCn/2CCn/2 -CCn/2

CCn,m generation:

(SF = 512)

Walsh

Matrix


TECHCOM ConsultingDL Scrambling Codes:

Pseudo noise codes used for cell separation

512 Primary Scrambling Codes

UL Scrambling Codes

Two different types of UL scrambling codes are

generated

Long scrambling codes of length of 38 400 chips = 10

ms radio frame

Short scrambling codes of length of 256 chips are

periodically repeated to get the scrambling code of

the frame length

Short codes enable advanced receiver structures in

future

DL & UL Scrambling Codes


Scrambling Code Set


Channelisation & Scrambling Codes


Channelisation & Scrambling Codes

Channelisation code Scrambling code

Usage Uplink: Separation of physical data

(DPDCH) and control channels

(DPCCH) from same terminal

Downlink: Separation of downlink

connections to different users within one

cell

Uplink: Separation of mobile

Downlink: Separation of sectors (cells)

Length 4256 chips (1.066.7 s)

Downlink also 512 chips

Different bit rates by changing the length

of the code

Uplink: (1) 10 ms = 38400 chips or (2)

66.7 s = 256 chips

Option (2) can be used with advanced

base station receivers

Downlink: 10 ms = 38400 chips

Number of codes Number of codes under one scrambling

code = spreading factor

Uplink: 16.8 million

Downlink: 512

Code family Orthogonal Variable Spreading Factor Long 10 ms code: Gold code

Short code: Extended S(2) code family

Spreading Yes, increases transmission bandwidth No, does not affect transmission

bandwidth


Spreading & Processing Gain

FrequencyPow

er

density

(Watts/H

z)

Unspread narrowband signal

Spread wideband signal

Bandwidth W (3.84 Mchip/sec)

User bit rate

R

sec84.3

MchipconstW

Processing gain:

R

WdBGp


Processing Gain Example

Voice user (R=12,2 kbit/s)

Packet data user (R=384 kbit/s)

Pow

er

density

(W/H

z)

R

Frequency (Hz)

Gp=W/R=24.98dB

Pow

er

density

(W/H

z)

R

Gp=W/R=10 dB

Spreading sequences have a different length

Processing gaindepends on the user

data rate


QPSK Modulation

The basic idea with QPSK modulation, which is used in WCDMA


UMTS Protocol Stack

Layer-1

Layer-2L

Layer-2U

Layer-3

OSI


TECHCOM ConsultingPhysical Layer Functions (Layer-1)

-Forward error correction, coding, interleaving

-Measurements

-Soft handover execution

-Multiplexing/mapping of services on dedicated physical

code channels

-Modulation, spreading, demodulation, dispreading of

physical channels

-Frequency and time synchronization

-Fast closed-loop power control

-RF processing

MAC Layer Function (Layer-2L)

-Selection of appropriate transport format

-Service multiplexing on RACH, FACH and dedicated

channels

-Scheduling

-Access resolution on RACH

-Contention resolution on RACH etc..

Radio Protocol Stack Functions

RLC Functions (Layer-2U):

-Segmentation and assembly

-Transfer of user data

-Error correction through retransmission optimized for

physical layer

-Sequence integrity

-Flow control

PDCP Function (Layer-2U)

-Service specific. Exists only in the User Plane and only

for services from PS domain. Contains compression

methods needed for better spectral efficiency

RRC Functions:

-Broadcast of system information

-Radio Resource handling

-Control of requested QOS

-UE measurements reporting and control of the reporting


Channels Overview


UMTS Radio interface Channels


TECHCOM ConsultingTraffic Channels

Dedicated Traffic Channel (DTCH)

Common Traffic Channel (CTCH)

Control Channels

Dedicated Control Channel (DCCH)

Common Control Channel (CCCH)

Broadcast Control Channel (BCCH)

Paging Control Channel (PCCH)

Logical Channels


TECHCOM ConsultingDedicated Channels

Dedicated Channel (DCH)

Common Channels

Random Access Channel (RACH)

Forward Access Channel (FACH)

Broadcast Channel (BCH)

Paging Channel (PCH)

Common Packet Channel (CPCH)

Downlink Shared Channel (DSCH)

Transport Channel


TECHCOM ConsultingDedicated Channel

DPDCH (Dedicated Physical Data Channel)

PDSCH ( Physical Downlink Shared Channel)

Common Channel

DPCCH (Dedicated Physical Control Channel)

PRACH (Physical Random Access Channel)

PCPCH (Physical Common Packet Channel )

DPCCH (Dedicated Physical Control Channel)

PCCPCH (Primary Common Control Physical Channel)

SCCPCH (Secondary Common Control Physical

Channel)

CPICH (Common Pilot Channel )

Physical Channel

PICH (Paging Indicator Channel)

AICH (Acquisition Indicator Channel)

CSICH (CPICH Status Indicator Channel)


UMTS Radio Channel Mapping

BCCH

PCCH

CCCH

DCCH

DTCH

CTCH

BCH

CPCH

DSCH

DCH

RACH

FACH

PCH

P-CCPCH

S-CCPCH

P-CPICH

PRACH

DPDCH

DPCCH

PDSCH

PICH

P-SCH

S-SCH

AICH

S-CPICH

PCPCH

Logical Channels Transport Channels Physical Channels

DPCHKey: Uplink

Downlink

Bidirectional

Data Transfer

Association

Control Ch

Traffic Ch

Common Ch (no FPC)

Common Ch (FPC)

Dedicated Ch (FPC)

Info Channels

Assoc Channels

Fixed Channels


Cell Breathing

NodeB 1 NodeB 2

Fully loaded system

Unloaded system

The more traffic, the more interference and the shorter the distance must be between the NodeB and the UE

The traffic load changes in the system causes the cells to grow and shrink with time.


UL/DL Capacity Limitation

Scenario 1: Capacity limitation due to UL interference

The cell cant serve UE1 because the increase in UL interference by adding the new user would be too high, resulting in a high risk of drops

Scenario 2: Capacity limitation due to DL power

The cell cant serve UE2 because its using all its available power to maintain the connections to the other UEs

UE2

Scenario 1 Scenario 2

UE1


Code Blocking


Base band processing units general

Base band units of Flexi and Ultra BTS product line:

Flexi WCDMA System Module (FSM)

Used in Flexi Node B

2 FSMs are allowed in maximum in the NodeB

Consists of FSP cards (Functional Signal Processing unit)

CE (Channel Element) is basic processing capacity unit

Wideband Signal Processing unit (WSP)

Used in UltraSite and MetroSite NodeB

Max No of WSPs per NodeB depends on its type (18 WSPs in maximum)

CE is basic processing capacity unit

Both base band units provide Rx and Tx channel processing (scrambling and descrambling,

interleaving UL/DL, spreading and despreading, channel coding and decoding)


Channel Element & Spreading Factor Requirement

Rel1 HW (FSMB)

User data CE UL/minSF

CE DL/minSF

AMR (voice) 1/ SF64 1/ SF128

WB-AMR 1 / SF64 1 / SF128

PS 16 kbps 1 / SF64 1 / SF128

PS 32 kbps 2 / SF32 2 / SF64

PS 64 kbps 4 / SF16 4 / SF32

PS 128 kbps 4 / SF8 4 / SF16

PS 256 kbps 8 / SF4 8 / SF8

PS 384 kbps 16 / SF4 16 / SF8

CS 64 kbps 4 / SF16 4 / SF32

CS 14.4 kbps 1 / SF64 1 / SF128


Maximum Ratio Combining

Multiple paths possibly cause destructive interference between different replica of the desired signal

Multiple path should be at 1 chip delay to make it usable

Multipath Propagation

Time Dispersion

10 2 3


TECHCOM ConsultingConcept :

Each Multipath component is called a Finger

Estimation of radio channel properties (Dealy, Amplitude

& Phase) for each finger

The RAKE receiver combines multi path components by

coherent combining of multi patch components belonging

to respective user.

The RAKE Receiver


Maximum Ratio Combining- RAKE

Each finger tracks a different multipath component and other cells during Soft Handover

A maximum ratio combining produces the output

Search Finger is used to determine whne to perform handovers

C

O

M

B

I

N

E

R

Power measurements of neighbouring NodeBs

Sum of individual multipath components

Finger #1

Finger #2

Finger #3

Finger #N

Buffer/delay

Correlators

Channel

Searcher Finger


Power Control- Introduction

Signal is blocked by signal

from UE near base stationOne UE can block

the whole cell

Near & Far Effect in Uplink

In the downlink, the capacity is determined by the transmit code power for each

connection. Therefore, it is essential to keep the transmission power at a minimum level

while ensuring adequate signal quality at the receiving end.


TECHCOM ConsultingConcept :

Power is a common resource in WCDMA

Goal :

Ensure sufficient received energy per information bit for

all communication links

Strategy :

Power control on COMMON CHANNELS ensures there is

sufficient coverage to establish connections and transfer

date on common transport channels

Power control on DEDICATED CHANNELS (DCH)

ensures sufficient connection quality while minimizing

impact on other connections.

Power Control or Rate Control

Power control strategy (R99): adjust transmitted power

while keeping the data rate constant

Rate control strategy (HSDPA): adjust the data rate while

keeping the transmitted power constant

Power Control


Power Control

Open loop power Control

Initial power setting

Outer Loop (RNC)

Adjust quality target dependent on performance

Inner Loop (fast power control-Node B)

compensates for fading channels

needs dedicated control channel for power control commands

Without power control

PTX

tfading

channel

t

PRX

fadingchannel

t

PTX

t

PRX

With power control


Power Control

Quality New SIR target

Quality(BLER) target

Send TPC(up/down)

to UEAdjust powerAccording toReceived TPC

Measure received SIR

Measure qualitye.g. CRC Error

RNC Node-B UE

Outer loop Inner loop


Soft/Softer Handover

Soft/softer handover is important for efficient power control. Without soft/softer handover there would be near- far

scenarios of a UE penetrating from one cell deeply into an adjacent cell without being power controlled by the latter.

Soft Handover: UE connected to two or more NodeB at the same time

Softer Handover: UE connected to two or more sector of the same NodeB


Soft/Softer Handover & Power Control

Uplink Power is based on information (TPC bits) from both RBSs to which the UE is connected. The UE will

decrease its output power in all cases except when both RBSs send increase power commands.

Downlink Power control for both RBSs is based on one signal (TPC bits) from the UE (it does not distinguish

between RBSs and the decision is base on the combined output from the RAKE receiver

UL Power control DL Power control


Soft/Softer Handover & Power Control


Neighbour list Combination procedure

Active Set may contain cells, which are not necessary adjacencies with each other.

The list of cells to be measured is send by the RNC in a MEASUREMENT CONTROL message and is changed at every Active Set Update. The RNC then combines the

Neighbour lists according to the following rules:

1. Active set cells are included

2. Neighbour cells which are common to three active set cells are included

3. Neighbours which are common to the controlling cell and a second active set cell are included.

(cell, other than the controlling cell, which has the highest CPICH Ec/Io)

4. Neighbour cells which are common to two active set cells are included

5. Neighbour cells which are defined for only one active set cell are included

6. Neighbours which are defined only for the second ranked cell are included

7. Neighbours which are defined only for the third ranked cell are included

If the total number of cells to be measured exceeds the maximum value of 32 during any step then handover control stops the Neighbour list generation


Neighbour list Combination procedure

Because of the combination explained in the previous slide, it is possible to measure handover activity between 2 cells which do not have an adjacency defined between them.

In this example intra-frequency adjacencies exist between cells 2-6 and 6-7, but not between 2-7. Activity is measured when the lists of cells 2 and 6 are combined and 7 can be added,

while 2 is still the best cell in the Active Set. The same effect applies for Inter-System list

combining

Neighboured

Not neighboured

1

23 4

5

6

7

89

UE path

Neighboured

Not neighboured

1

23 4

5

6

7

89

UE path


Hard Handover

UE move

Target BSSource BS

time

Data UE received/

sent

GAP of communication

Features of hard handover:

HHO causes a temporary disconnection for RT radio access bearer and is lossless for Non Real

Time bearers (NRT).

The UE must either be equipped with a second receiver or support compressed mode to execute

inter-system/inter-RAT measurement.


Content

WCDMA Basic Theory


HSPA Overview



TECHCOM ConsultingRRM is responsible for optimal utilisation of the radio

resources:

Transmission power and interference

Logical codes

The trade-off between capacity, coverage & quality is

done all the time

Minimum required quality for each user (nothing less

and nothing more)

Maximum number of users

The radio resources are continuously monitored and

optimised by several RRM functionalities



RRM Functionality

PC

HC

For each connection/user

LC

AC

For each cell

PS

RM

LC Load Control

AC Admission Control

PS Packet Scheduler

RM Resource Manager

PC Power Control

HC HO Control


TECHCOM ConsultingAdmission Control checks that admitting a new user

will not sacrifice planned coverage or quality of

existing connections

Admission control handles main tasks

-Admission decision of new connections

-Take into account current load conditions (from LC)

and load increase by the new connection

-Real-time higher priority than non-real time

-In overload conditions no new connections admitted

Connection QoS definition

-Bit rate, BER target etc.

-Connection specific power allocation (Initial,

maximum and minimum power)

Admission Control (AC)

AC is used to decide whether a new RAB can be

admitted or a current RAB can be modified.

Admission control is done in uplink and downlink

separately.

The strategy is that a new bearer is admitted only if the

total load after admittance stays below the thresholds

defined by RNP.


Admission Control Strategy

Ltotal old + I < L threshold

P totalold + Ptotal < P threshold


TECHCOM ConsultingTechnical classification of load control:

-Call Admission Control

-Load Balance between cells

- Congestion Control

Classification of Load Control

Definition of Air interface Load:

-Wideband power-based uplink loading:

-Wideband power-based downlink loading:

rxTotal

othownUL

P

II

maxtx

txTotalDL

P

P


TECHCOM ConsultingPS allocates available capacity after real-time (RT)

connections to non-real time (NRT) connections

-Each cell separately

-In overload conditions bit rates of NRT connections

decreased

PS selects allocated channel type (common or

dedicated)

PS relies on up-to-date information from AC and LC

Capacity allocated on a needs basis using best effort approach

-RT higher priority

Packet Scheduler (PS)


Resource Manager (RM)

Responsible for managing the logical radio resources of the RNC in co-operation with AC and PS

On request for resources, from either AC(RT) or PS(NRT), RM allocates:DL Channelization codeUL Scrambling code

Code Type Uplink Downlink

Scrambling codes

Spreading codes

User separation Cell separation

Data & control channels from same UE Users within one cell

Code Tree Management:

Code selection Code Tree re-arrangement


TECHCOM ConsultingFast, accurate power control is of utmost importance

particularly in UL -UEs transmit continuously on same frequency Always interference between users

-Poor PC leads to increased interference reduced capacity

Every UE accessing network increase

interference

-PC target to minimise the interference Minimize transmit power of each link while still maintaining the

link quality (BER)

Mitigates 'near far effect in UL by providing minimum required power for each connection

Power control has to be fast enough to follow

changes in propagation conditions (Slow & Fast

Fading)

-Step up/down 1500 times/second

Power Control in WCDMA (PC)

In HSDPA transmit the power is constant

Channel conditions are taken into account by changing the

signal modulation and coding (Link Adaptation) Higher bit rates in better conditions


Classification of Power Control

Power Control

Uplink power control

Open loop power control

Inner loop power control

Outer loop power control

Downlink power control

Open loop power control

Inner loop power control

Outer loop power control

Compared with open loop

power control, inner loop and

outer loop power control are

called closed loop power

control


TECHCOM ConsultingThe uplink and downlink frequencies of WCDMA are

within the same frequency band.

Uplink open-loop power control

-Based on the calculation of the open-loop power control,

the UE sets the initial powers for the first PRACH

preamble and for the uplink DPCCH before starting the

inner-loop power control.

Downlink open-loop power control

In the down link, the open-loop power control is used to

set the initial power of the downlink channels based on the

downlink measurement reports from the UE.

Open Loop Power Control


Open Loop Power Control

Convergence of inner loop

power control

time

power

time

power Accurately calculate initial transmitting power of inner

loop needed to minimize the

time of convergence

Reduce the impact on system load


Inner Loop Power Control

Objective of power control:

balance the received energy

per bit of different UEs at base

station

NodeB UE

Power Control

Measure and compare SIR of received signal

Inner loop

Set SIRtar

1500Hz

Each UE has its

own power control

loop


BLER-SIR

The aim of the outer-loop PC algorithm is to maintain the quality of the connection at the level defined by the quality requirements of the bearer

service.

According to principles of wireless communication, BLER may change with the wireless environment under fixed SIR.

BLE

R

BLER

Different curves

correspond with

different multi-path

environment.

SIR


Outer Loop Power Control

NodeB UE

Power Control

Measure & compare

SIR of received signal

Inner loop

Set SIRtar

Traffic data with

steady BLER can

be acquired

Measure BLER of

transport channel

Outer loop

RNC

Measure & compare

BLER of received data

Set BLERtar

10-100Hz


Downlink Power Control

NodeB

Set SIRtar

Power Control

Measure and compare SIR

Measure and compare BLER

Outer

loop

Inner loop UE physical layer

UE Layer 3

Downlink inner loop and outer loop power control

10-100Hz1500Hz


TECHCOM ConsultingHC is responsible for:

-Managing the mobility aspects of an RRC

connection as UE moves around the network

coverage area

-Maintaining high capacity by ensuring UE is always

served by strongest cell

Handover Control

Classification of Handover:

-Softer Handover

-Soft Handover

-Hard Handover

-Intra-Frequency hard handover

-Inter-Frequency hard handover

- Inter RAT handover (Between WCDMA & GSM

Intra-frequency hard handover includes two instances:

(1)handover between two RNCs without IUR interface

(2)code handover in the cell


TECHCOM ConsultingFor soft handover, the combination of multiple RL uses

maximum ratio combination (RAKE combination) in

downlink and selection combination in uplink.

When the two cells in soft handover belong to the

same NodeB, maximum ratio combination could be

used in uplink. In this case the handover is softer

handover.

Softer handover has higher priority in handover

schemes because maximum ratio combination has

larger gain than selection combination.

For soft handover, selection combination in uplink

completes in RNC.

Soft/Softer Handover

Soft Handover Measurement:

Active Set: Including all cells currently participating in a

SHO connection of a terminal.

Neighbour Set/Monitored Set: This set includes all cells

being continuously monitored/measured by the UE and

which are not currently included in the active set.


Soft Handover Measurement


TECHCOM ConsultingFeatures of hard handover:

-HHO causes a temporary disconnection for RT radio

access bearer and is lossless for Non Real Time bearers

(NRT).

-The UE must either be equipped with a second receiver

or support compressed mode to execute inter-

system/inter-RAT measurement.

Application of Hard Handover in 3G:

Intra-frequency hard handover: When inter-RNC SHO

cant be executed or is not allowed.

Inter-frequency hard handover: Load balance between

frequencies

Inter-RAT handover

-2G-3G smooth evolution

-The finite coverage range of initial phase of 3G

Hard handover

Selection of Handover Scheme

Handover scheme should be selected based on the traffic

QoS

-Soft handover can provide better service quality.

-Soft handover uses more system resource.

-Different sizes of active set and soft handover area use

different system resource and provide different QoSs.

-Hard handover would bring gap during calls.-Hard handover uses less system resource.

Consider both the QoS requirement and the occupation of

system resource by handover.

Make a tradeoff between occupation of system resource

and QoS


Compressed Mode

Objective of compressed mode: for UE to realize measurement and

synchronization to target cell when inter-frequency handover and

inter-RAT handover is required.


TECHCOM ConsultingCompressed Mode:

Intra-frequency neighbors can be measured

simultaneously with normal transmission by UE using a

RAKE receiver.

Inter-frequency or inter-RAT neighbors measurements

require the UE measuring on a different frequency, this

has either to be done with multiple receivers in the UE or

in the compressed mode (CM).

CM is to stop the normal transmission and reception for a

certain period of time, enable the UE to measure on the

other frequency.

The usage of compressed mode would reduce the system

performance

Complex algorithm is needed to decide when to enter

compressed mode.

Compressed Mode


Content

WCDMA Basic Theory


HSPA Overview



TECHCOM ConsultingProvide telecommunication professionals with the

basic understanding of HSPA, the high speed packet

access technologies (HSDPA, HSUPA), and related

applications, network architecture, and deployments.

The talk will present:

-the market drivers for UMTS HSPA

-the basic enabling techniques and terminology associated

with HSPA

- the basic operations of HSPA

- the HSPA implementation and performances

HSPA Objective


3G Enables Wider Options of Services


3G Enables Advanced Data Services


HSPA for Higher Speed


UMTS Data Rate Evolution


Applications Benefiting from HSPA


Release 99 Principles


DCH/FACH Comparison Summary


What will HSDPA Address?


HSDPA Enabling Technologies


Physical Layer Bit Rates (DL) - HSDPA

3GPP Release 5 standards introduced enhanced DL bit rates with High Speed Downlink Packet Access (HSDPA) technology

Shared high bit rate channel between users High peak bit rates

Simultaneous usage of up to 15 DL channelisation codes (In HSDPA SF=16)

Higher order modulation scheme (16-QAM) Higher bit rate in same band

16-QAM provides 4 bits per symbol 960 kbit/s / code physical channel peak rate

Coding rate

QPSK

Coding rate

1/4

2/4

3/4

5 codes 10 codes 15 codes

600 kbps 1.2 Mbps 1.8 Mbps

1.2 Mbps 2.4 Mbps 3.6 Mbps


16QAM

2/4

3/4

4/4




HSDPA


Common Channel for Data


Multi-Code Operation


Adaptive Modulation and Coding


Link Adaptation versus Power Control


Scheduling Comparison


HSDPA Scheduling and Retransmissions


Hybrid Automatic Repeat Request (HARQ)


HARQ Illustration


Comparison Summary


HSDPA Protocol Stack


HSDPA Channels


HSDPA Channels (continued)


HSDPA Operation Overview


HSDPA Channel Operation Timeline


HS-PDSCH


HS-DPCCH


HS-SCCH


Data Rate Example


Theoretical HSDPA Maximum Data Rate


Multi-code Transmission


Consecutive Assignments


Hybrid Automatic Repeat Request (HARQ)


Lower Coding Gain


Lower Coding Gain (continued)


16-QAM


Theoretical HSDPA Maximum Data Rate


Inter-TTI Interval


Retransmissions


ACK/NAK Repetitions


Node B Implementation Considerations


OVSF Allocation


Node B Transmit Power Allocation


CQI Report Processing


Node B Scheduler


HSDPA Cell Re-pointing Procedure


HSUPA Performance


Physical Layer Bit Rates (UL) - HSUPA

3GPP Release 6 standards introduced enhanced UL bit rates with High Speed Downlink Packet Access (HSUPA) technology

Fast allocation of available UL capacity for users High peak bit rates

Simultaneous usage of up to 2+2 UL channelisation codes (In HSUPA SF=2 4)

Coding rate

1/2

3/4

4/4

1 x SF4 2 x SF4 2 x SF22 x SF2 + 2 x SF4

480 kbps 960 kbps 1.92 Mbps 2.88 Mbps

720 kbps 1.46 Mbps 2.88 Mbps 4.32 Mbps

960 kbps 1.92 Mbps 3.84 Mbps 5.76 Mbps


Release 99 Uplink Packet Data


Release 99 Uplink Limitations


High Speed Uplink Packet Access (HSUPA)


Enhancements Provided by HSUPA


How are Enhancements Achieved?


HSUPA vs. HSDPA


Rise-over-Thermal Noise


Node B Scheduler for HSUPA


Rise-over-Thermal Loading


HSUPA Channel Operation


HSUPA Channel Operation (continued)


HSUPA Protocol Stack


HSUPA Uplink Channels


HSUPA Downlink Channels


HSUPA Channel Mapping


Uplink Channels


Downlink Channels


HSUPA Channel Timing


HSUPA Features (continued)


E-DCH Active Set and Mobility Support


HSUPA Serving Cell Change


Active Set Composition with HSUPA


Theoretical HSUPA Maximum Data Rate


E-DPDCH with SF4 and Puncturing


Lower Spreading Factor SF2


Multi-code Transmission


HSUPA UE Capabilities


HSPA Technology

HSPA technology

Channel types

Physical Channels

Principle of HSPA


HSxPA Motivation and General Principle

Improved performance and spectral efficiency in DL and UL by introducing a shared channel principle:

Significant enhancement with peak rates up to 14.4 Mbps (28 Mbps in Rel7) in DL, and 2 Mbps (11.5 Mbps with 16QAM) in UL

Huge capacity increase per site; no site pre-planning necessary

Improved end user experience: reduced delay/latency, high response time

HSDPA (3GPP Rel5)

Fast pipe is shared among UEs

HSUPA (3GPP Rel6)

Dedicated pipe for every UE in UL

Pipe (codes and grants) changing

with time

E-DCH scheduling

Rel. 99

Dedicated pipe for every UE


HSDPA Overview

15 Code

Shared

transmission

16QAM

Modulation

TTI = 2 ms Hybrid ARQ

with incr. redundancy

Fast Link

Adaptation

Advanced

Scheduling

Benefit

Higher Downlink Peak rates: 14 Mbps

Higher Capacity: +100-200%

Reduced Latency: ~75 ms


HSDPA power is limited by the PtxMaxHSDPAparameter

Cell maximum TX

power

Common chs

HSDPA

Maximum

HSDPA power

(PtxMaxHSDPA)

Non-

HSDPA

power

Ptx

Time

Cell maximum TX power

Common chs

HSDPA

Non-HSDPA

power

Ptx

Time

HSDPA power is not limited, all available power can be allocated to HSDPA

Still PtxMaxHSDPA can be used to limit

HS-PDSCH Transmit power

The Packet Scheduler is responsible for determining the transmission power on the HS-PDSCH channels

Dynamic HSDPA power allocation is always used in BTS HSDPA power can be limited with PtxMaxHSDPA

HSDPA Dynamic Resource Allocation feature is activated with RNC parameter HSDPADynamicResourceAllocation

Disabled: PtxMaxHSDPA sent to BTS and used to limit the maximum HSDPA power Enabled: No power limitation sent to BTS, all available power allocated to HSDPA


Maximum code allocation for HSDPA

SF=1

SF=2

SF=4

SF=8

SF=16

SF=32

SF=64

SF=128

SF=256

15 HS-PDSCH codes

Up to three HS-SCCH codes

Codes for common

channels in the cell

Codes for associated DCHs and

non-HSDPA users

Used by 2 HSDPA UEs no SF256 available for the 3rd UE for

associated DCH

Used by AMR user only one SF128 code remains for associated

DCH

Used by HSDPA UE as associated DCH and HS-SCCH

Case1:

Case2:

Case1+2:

Code tree limitation makes it hard to have 15 codes allocated for HSDPA Still commonly 14 or 12 or lower amounts are easily available Note that current terminals support only 10 codes so 15 codes means more than 1 users per TTI

15 codes is available but not commonly for cells where has reasonable high traffic (noticing terminal limitation 10 codes, thus fully utilise 15 codes needs minimum 2 HSDPA users)

Case 1: Allocation of 15 is not possible when more than 2 HSDPA users are active (i.e. 3 HSDPA users) Case 2: Allocation of 15 is not possible (with two HSDPA users) when 1 AMR12.2 user exists in the cell


HSDPA - UE Categories

QPSK and 16QAM modulation with multi code transmission used to achieve high data rates

12 different UE categories defined, categories are characterized by

Number of parallel codes supported

Minimum inter-TTI interval

Theoretical peak bit rate up to 14.4 Mbps for category 10 UE using 15 codes and 16QAM


HSDPA Code Multiplexing

With Code Multiplexing, maximum of three UEs can be scheduled during one TTI from single

cell

Multiple HS-SCCH channels (max 3 in RAS06)

One for each simultaneously receiving UE

Available HS-PDSCH codes and HS-PDSCH power of cell are divided between UEs

HS-PDSCH codes actually used depends on the channel conditions of a UE

Important when cell supports more codes than UEs do

Cell supports 15 HS-PDSCH codes, Cat6 and Cat8 UEs => 3 users can be

scheduled on TTI

BTS must also be capable of 10/15 codes in order to dynamically adjust HS-PDSCH codes

HS-PDSCH

HS-PDSCHHS-PDSCH

HS-PDSCH

HS-PDSCH

cat 6

HS-PDSCH

HS-PDSCH

HS-PDSCH

HS-PDSCH

HS-PDSCH

HS-SCCH

HS-SCCH

cat 6 cat 6 cat 6cat 8

HS-SCCH

HS-PDSCH

HS-PDSCH

HS-PDSCH

HS-PDSCH

HS-PDSCH


HSUPA Overview

TTI = 10 ms1-4 Code

Multi-Code

transmission

Fast

Power ControlHybrid ARQ

with incr. redundancy

NodeB

Controlled

Scheduling

Benefit

Higher Uplink Peak rates: 2.0 Mbps

Higher Capacity: +50-100%

Reduced Latency: ~50-75 ms


HSUPA - UE Categories

BPSK modulation with multi-code transmission used to achieve high data rates

6 different UE categories defined, categories are characterized by

Number of parallel codes supported

Support of 2ms TTI - 10ms TTI supported by all the HSUPA UEs

Theoretical peak bit rate up to 5.74 Mbps for category 6 UE using 2 ms TTI

No coding and no retransmissions - all bits must be delivered correctly over the air

11484

20000

20000

5772

20000

14484

2798

14484

7110

Transport Block size

2 Mbps102 x SF24

2.89 Mbps22 x SF24

1.45 Mbps102 x SF42

1.40 Mbps22 x SF42

2 Mbps102xSF2 + 2xSF46

6

5

3

1

HSUPACategory

2

10

10

10

TTI

2xSF2 + 2xSF4

2 x SF2

2 x SF4

1 x SF4

Codes x Spreading

5.74 Mbps

2 Mbps

1.45 Mbps

0.71 Mbps

Data rate


Thank You

Chapter 1_ 3G Technology Funamentals

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Transcript of Chapter 1_ 3G Technology Funamentals