Part 1 fundamentals of 3 g

Part 1Fundamentals of 3G

AMPS (Advanced

Mobile Phone

Systems

North American Standard in

cellular band (800 MHz)

TACS (Total Access

Communication

System)

UK originated standards based on AMPS in 900

MHz band

NMT (Nordic Mobile

Telephony System)

Scandinavian standard in

450 MHz and 900 MHz band

C-450

German standard in

450 MHz band

JTACS (Japanese

Total Access Communica

tion System)

Japanese standard in

900 MHz Band

1st Generation Standards

30 KHz30 KHz30 KHz30 KHz30 KHz30 KHz30 KHz30 KHzFr

eque

ncy

FDMA — Frequency Division Multiple Access

IS-136 ( D-AMPS ) PDC (Japan)

IS-95 CDMA

(cdmaOne)

GSM

1st Generation Standards

Freq

uenc

y

Time

200 KHz

200 KHz

200 KHz

200 KHz

One timeslot = 0.577 ms One TDMA frame = 8 timeslots

Except IS-95 all are TDMA based

1990’s• 1st system to use Digital modulation

• Variety of Multiple Access strategies

• Voice and low rate circuit switched data

• Same technology allows international roaming

• Secure air interface

The Second Generation

www.escsl.com

http://www.escsl.com/

UMTS Evolution / 3GPP Releases

Year1999 2001

matured GSM/GPRS CN+ UTRAN+ WCDMA Air Interfaceup to 384 kbps (2 Mbps)

• Bearer independent CS CN

• HSDPA (14 Mbps)• IMS Phase 1

• HSUPA (5.76 Mbps)• IMS Phase 2

Release 99 Release 99

Release 4Release 99

Release 4

Release 5

Release 99

Release 4

Release 5

Release 6

2002/03 2005

UMTS Evolution / 3GPP Releases

Year2007 2008/09

Release 99

Release 4

Release 5

Release 6

Release 7

Release 99

Release 4

Release 5

Release 6

Release 7

Release 8

Release 99

Release 4

Release 5

Release 6

Release 7

Release 8

Release 9

2009/10

Release 99

Release 4

Release 5

Release 6

Release 7

Release 8

Release 9

Release 10

2010/11

HSPA + or eHSPA

UMTS Architecture [1]

CN

UTRAN

UE

Uu

Iu

UTRAN UMTS Terrestrial Radio Access NetworkCN Core NetworkUE User Equipment

RNS

Iub


Node BNode B

RNC

RNS

Iub

Node BNode B

RNC

Core Network

Iur

Iu Iu

GMSC AUC

SGSN

GGSN

VLR MSC

HLR

RNC RNC

EIR

Node B Node

B

NodeB Node

B

To PSTN

Core Network

UTRAN

C

DF

Gs

Gf

Gr

Gc

Iu-CS Iu-PS

Iur

Lu-CS

GI

Gp

To IP Network

Other PLMN

Iub

Iub

AUC Authentication centre

EIR Equipment Identity Register

GGSN Gateway GPRS Support NodeHLR Home Location RegisterMSC Mobile Switching Centre

PLMN Public Land Mobile Network

RNC Radio Network Controller

RNS Radio Network Subsystem

SGSN Service GPRS Support Node

UTRAN (UMTS Terrestrial Radio Access Network

VLR Visitor Location Register

RNSRNS

Gn


UMTS Architecture [4] R99 Network Architecture

Network Nodes

1. User Equipment

• Consist of ME and USIM• The Mobile Equipment (ME) is the radio terminal used for

radio communication over the Uu interface• The UMTS Subscriber Identity Module (USIM) is a smartcard

that holds:– the subscriber identity, – performs authentication algorithms, – stores authentication and encryption keys – subscription information that is needed at the terminal

Core Network [1]

1. Home Location Register – HLR• is a database located in the user’s home system that stores

the master copy of the user’s service profile• It is created when a new user subscribes to the system, and

remains stored as long as the subscription is active2. Mobile Switching Centre/Visitor Location Register –

MSC/VLR• It is the switch (MSC) and database (VLR) that serves the UE in

its current location for Circuit Switched (CS) services• MSC switches the CS transactions• VLR holds a copy of the visiting user’s service profile and more

precise information on the UE’s location within the serving system

Core Network [2]

3. Gateway MSC – GMSC• It is the switch at the point where UMTS PLMN is connected

to external CS networks• All incoming and outgoing CS connections go through GMSC

4. Serving GPRS Support Node – SGSN• Its functionality is similar to that of MSC/VLR but is typically

used for Packet Switched (PS) services

5. Gateway GSN – GGSN• functionality is close to that of GMSC but is in relation to PS

services

Interfaces1. Cu interface• This is the electrical interface between the USIM smartcard

and the ME.• The interface follows a standard format for smartcards.2. Uu interface• It is the WCDMA radio interface• The UE accesses the fixed part of the system through this

interface3. Iu interface• It connects UTRAN to the CN• the open Iu interface gives UMTS operators the possibility of

acquiring UTRAN and CN from different manufacturers

4. Iur interface• The open Iur interface allows soft handover between RNCs

5. Iub interface• It connects a Node B and an RNC• UMTS is the first commercial mobile telephony system where

the Controller–Base Station interface is standardised as a fully open interface

Interfaces

Radio Access Network [1]

Radio Access Network [1]1. Radio Network Controller• It is responsible for control of the radio resources in its area• One RNC can control multiple Node Bs• Its functionality is equivalent to BSC in GSM/GPRS• RNCs can autonomously handles handovers without involving MSCs and SGSNs

Admission Control

Radio Resource Control (RRC)

Radio Bearer Set-up / Release

Code Allocation (Outer Loop) Power Control

Congestion Control (Packet

Scheduling)

Handover Control

(incl. Combining /

Splitting)

S-RNS Relocation (S-RNC/D-RNC)

Ciphering and Deciphering

Protocol conversion (Iu

« Iub, Iur)

ATM switching and

multiplexingO&M tasks

Radio Resource Management functions of RNC

PC

HC connection basedfunctions

LC

AC network basedfunctions

PS

RM

· Packet Scheduler - PS· Resource Manager - RM· Admission Control - AC· Load Control - LC

· Power Control - PC· Handover Control - HC

Radio Access Network [1]1. Node B• It is responsible for air interface L1 processing• Also performs some RRM function such as inner loop power control• It is equivalent to BTS in GSM/GPRS• Node Bs are typically collocated with GSM BTSs• The enigmatic term ‘Node B’ was initially adopted as a temporary term during the

standardization process, but then never changed

Spreading Scrambling Channel Coding Interleaving Modulation

Fast Power Control

Measurement reports to RNC

ATM transmission

Micro-diversity Combining (in

Softer HO)

3GPP Rel-4 Network ArchitectureMSC

ServerGMSC Server

The 3GPP R4 introduces separation of connection, its control, and services for CN CS domain.• Media Gateway (MGW): an element for maintaining the connection and performing switching function when required.• MSC server: an element controlling MGW.

UMTS - Hierarchy of Bearers

3GPP TS 23.107, QoS Concept and Architecture

TETE MTMT UTRANUTRANCN Iuedgenode

CN Iuedgenode

CNGateway

CNGateway

TETE

UMTS

End-to-End Service

TE/MT Local Bearer Service

External Bearer Service

UMTS Bearer Service

Radio Access Bearer Service CN Bearer Service

Backbone Bearer Service

Iu Bearer Service

Radio Bearer Service

UTRA FDD/TDD Service

Physical Bearer ServiceRAB

RABs

Multi-Access Radio Techniques

UMTS is designed to work in both TDD and FDD mode

But FDD option has been preferred by majority of 3G operators

Multiple Access Approaches

Frequency Division Multiple Access

Each User has a unique frequency

(1 voice channel per user)

All users transmit at the same time

AMPS, NMT, TACS

Use

r 1

Use

r 2

Use

r 3

Frequency

Each Transmitter has a unique spreading code

Each Data Channel has a unique orthogonal code

Many users share the same frequency and time

IS-95, cdma2000, WCDMA

Frequency

Code Division Multiple Access

SpreadSpectrumMultipleAccess

Multiple Transmitters

and

Multiple Data Channels

Each User has a unique time slot

Each Data Channel has a uniqueposition within the time slot

Several users share the same frequency

IS-136, GSM, PDC

Time Division Multiple Access

Use

r 1

Use

r 2

Use

r 3

Use

r N

Time

UMTS Core Band ( or 2.1 GHz Band or Band I )

DECT UMTS MSS UMTS UMTS MSSTDD FDD

1880 1900 1920 1980 2010 2025 2110 2170 2200

TDD FDD

TDD Bands : _ _ _ _ _ _ to _ _ _ _ _ _ _ _ MHz

&

_ _ _ _ _ _ to _ _ _ _ _ _ _ _ MHz

FDD Bands : Uplink : _ _ _ _ _ to _ _ _ _ _ _ _ _ MHz

&

Downlink: _ _ _ _ _ _ to _ _ _ _ _ _ _ _ MHz

Wideband CDMA Specifications• Wide band CDMAMultiple access

• FDD Transmission mode

• 3.84 Mcps Chip rate

• 5 MHz Carrier spacing

• 10 msFrame size

• Variable-spreading factorSpreading technique

• ½ & 1/3 rate convolutional coding and 1/3 Turbo CodingChannel Coding

• QPSK (DL ) and BPSK (UL)Modulation

Main Parameters [1]

• WCDMA is a wideband Direct-Sequence Code Division Multiple Access (DS-CDMA) system

• user information bits are spread over a wide bandwidth by multiplying the user data with quasi-random bits (called chips)

• to support very high bit rates (up to 2 Mbps), the use of a variable spreading factor and multi-code connections is supported

• The chip rate of 3.84 Mcps leads to a carrier bandwidth of approximately 5 MHz

Main Parameters [2]

GuardPeriod

f

t

Uplink

Downlink

Bandwidth 5MHz

Uplink Downlink

Bandwidth 5MHz

Separation 190MHzf

t Bandwidth 5MHz

UMTS-TDD(Time Division Duplex)

• Preparing the Data and Signaling for the UMTS Air Interface

Overview of the UMTS Air Interface (Uu)

Channel Coding

TxRAKE

Signalling Data

Channels

Radio Framing

Spreading &Channelisation

Scrambling

Modulation

Air interface

SMSSMSdefine the UE actions

The user data is coded,depending on the

applicationThe specifications

1Different channels carrydifferent information

2

Data is coded, framed,spread and channelised

The signal is nowscrambled

3

The signal is modulated on a frequency to

represent binary values4The UE uses a special

receiver to RAKE throughthe air interface

5

Error Correction Code Parameter

Transport Channel Type

Coding Scheme Coding Rate

BCH

Convolutional code1/2

PCH

RACH

DCH,FACH

1/3, 1/2

Turbo coding 1/3

• 1/2 and 1/3 rate convolutional channel coding and turbo coding will be implemented.

• Rate matching is used to "fit" the data bit rate so that itcorresponds to the pre-defined fixed bit rates of the air interface. Also puncturing can be used.

Channel coding, rate matching

RateMatching

- Convolutional coding- Interleaving

Baseband data (n kb/s)

- 30 kb/s- 60 kb/s- 120 kb/s- 240 kb/s- 480 kb/s- 960 kb/s

3.84 Mcps

1. 15 ksps2. 30 ksps3. 60 ksps4. 120 ksps5. 240 ksps6. 480 ksps7. 960 ksps

31 © 2005 Nokia V1-Filename.ppt /

yyyy-mm-dd / Initials

WCDMA frame structure

Slot # 0 Slot #14Slot# iSlot # 1

1 radio frame : Tf = 10 ms

Variable Bit Rate

Frequency

5MHz

Power

Time

Users Separated byCodes

High bit rate user

Low bit rate user

33 © 2005 Nokia V1-Filename.ppt /

yyyy-mm-dd / Initials

Channelisation and scrambling

SF = 1 SF = 2 SF = 4

ch,1,0 = (1)

ch,2,0 = (1,1)

ch,2,1 = (1,-1)

ch,4,0 =(1,1, 1, 1)

ch,4,1 = (1,1,-1,-1)

ch,4,2 = (1,-1,1,-1)

ch,4,3 = (1,-1,-1,1)

Data (Baseband, Channel Coded & Rate-Matched)

Spread and Combined with Channelisation Code

Data is Spread...

…by a certain factor. The channelisation codeis selected based upon how much the data is

spread

Data

Channelisation CodeScrambling Code

Downlink Example

Bit rate Chip rate Chip rate

Page 22

Spreading Principles

User 1

User 2

User 3

Narrow-band data signals

Spread Spectrum signals

1

2

3

Users transmit their spread spectrum signals simultaneously

1&2&3

Output of user 2’s receiver

2

1 &3

Spreading and Despreading [1]

Code Usage

In the Uplink (UE BTS), the user's data and signalling information is separated by Channelisation Codes

datasignalling

In the Downlink (BTSUE), cells are

seperated by Scrambling Codes

In the Uplink

(UE BTS), terminals are separated by Scrambling Codes

In the Downlink (BTS UE), user connections are separated by Channelisation Codes

Dedicated User Channel

channelization Codes

CC1, CC2CC3, CC4

CC5, CC6, CC7

CC1 , CC2, CC3CC1, CC2

CC1, CC2, CC3, CC4

Uplink: Channelization Codes used to distinguish data (and control) channels coming from each UE

Downlink: Channelization Codes used to distinguish data (and control) channels coming from each cell

(Also called Walsh codes or spreading codes)

o o o o o oSF = 1

Cch,1,0 =1

SF = 2

Cch,2,1 =10

Cch,2,0 =11

SF = 4

Cch,4,0 =1111

Cch,4,2 =1010

Cch,4,1 =1100

Cch,4,3 =1001

channelization Code tree

• Adapts user bit-rate to code length• In reality, multipath, small timing errors diminish

the usable code spaceChip Rate = 3.840 Mcps

480 kb/s 480 kb/s 480 kb/s 480 kb/s 480 kb/s 480 kb/s 480 kb/s 480 kb/s

1

1-1 11

1-11-1 1-1-11 11-1-1 1111

1-11-11-11-11-11-1-11-11 1-1-111-1-111-1-11-111-1 11-1-111-1-111-1-1-1-111 1111-1-1-1-1 11111111

Example: 8 users; one 8-bit code per user

channelization Codes

Scrambling 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)

Downlink Scrambling Codes

• Downlink Scrambling Codes– Each Cell is assigned one and only one Primary Scrambling Code (of 512)– Secondary Scrambling Codes may be used over part of a cell, or for other data

channels

Primary SC0

Secondary Scrambling

Codes

(15)


Codes

(15)


Codes

(15)


Codes

(15)

Code Group #1 Code Group #64

8192 Downlink Scrambling CodesEach code is 38,400 chips of a 218 - 1 (262,143 chip) Gold Sequence

Primary SC7 Primary SC504 Primary SC511

SymbolData

1-1

1-1

1-1

1-1

1-1

Chip Spreading

Spread Signal =Data * Code

Spreading code

Spreading code

Data=Spread signal * Code

Despreading


1-1

-11

-1 1

8

-8

-88

-11

Desired SignalDesired Spread Signal

Spreading code

Data after Despreading

Data after Integration

Other user’s DataOther Spread signal

Other signal after despreading

Other signal after Integration


• In WCDMA, the terminal employs a RAKE receiver to handle Multipath propagation. The RAKE consists of receivers), adjustable-by-system delay functionality, code generator, and gain and phase tuning equipment. One Multipath component that the RAKE recognizes is called a finger. Typically, RAKE is able to handle several fingers. One of these fingers receives the signal from the Uu interface and tries to open it with the code used for the connection.

• The second finger receives the same signal from the Uu interface, and the code used for this connection is inserted to the receiver after a short, adjustable delay. When the signal is demodulated and regenerated, the outcomes of the fingers can be summed together.

RAKE receiver

CDMA Rake Receiver• Each RAKE finger tracks a different multipath component

– Sliding correlator used to obtain a correlation peak for each multipath component

– Also used to track other cells during soft handover• Searcher finger is used to measure other cells (for handover)

Finger #1

Finger #2

Finger #3

Finger #N

Buffer/delayCorrelatorsChannel

C

O

M

B

I

N

E

RPower measurements of neighbouring BS

Sum of individual multipath components:- maximum ratio- strongest select- equal gain

Searcher Finger

• Simplified Block Diagram of the RAKE Receiver

Modulation

Split real&

ImageParts

tcsin

tccos

Complex-valuedchip sequencefrom spreadingoperations

S

Re(S)

Im(S)

DL HSDPA

QPSK 16QAM

64QAM

DCH

QPSK

UL

HSUPA

BPSK 4PAM

DCH

BPSK

Logical, Transport & Physical Channels

Definition of Channels

The MAC sub-layer is responsible for

mapping logical channels onto transport channels.

The physical layer is responsible for

mapping transport channels onto physical channels.

Logical Channel

• Type of information to be transmitted e.g., traffic or control logical channels.

Transport Channel

• How and with what format data is transmitted through physical links.

Physical Channel

• Unit of radio resource of a radio system e.g., frequency band, time slot, code, etc.

Logical Channels in UL and DL

Abbr. Channel’s Name

1 BCCH Broadcast Control Channel

2 PCCH Paging Control Channel

3 CCCH Common Control Channel

4 DCCH Dedicated Control Channel

5 DTCH Dedicated Traffic Channel

6 CTCH Common Traffic Channel

Abbr. Channel’s Name

1 CCCH Common Control Channel

2 DCCH Dedicated Control Channel

3 DTCH Dedicated Traffic Channel

DL UL

Mapping of Transport Channels onto Phy. ChannelsTransport Channels

PRACH

RACH

DPCCH

DPDCH

DCH

Physical channels

P-CCPCH S-CCPCH Physical

channelsAICH PICH P-SCH

DPDCH CPICH

Transport Channels

BCH FACH PCH DCH

S-SCH

Dedicated Transport Channel

1. DCH – Dedicated Channel• Downlink/uplink Transport channel• A point-to-point channel allocated to a specific user• Carries information intended for the given user including data

and higher layer control information• Characterised by features such as

– fast power control – fast data rate change on a frame-by-frame basis– possibility of transmission to a certain part of the cell

Transport Channels [2]

Common Transport Channels

1. BCH – Broadcast Channel• It is a downlink channel• Used to broadcast system and cell-specific information over the

entire cell• The terminal cannot register to the cell without the possibility

of decoding the broadcast channel– transmit with relatively high power– low and fixed data rate


2. FACH – Forward Access Channel• It is a downlink channel • Used to carry control information to a mobile station when

the system knows the location cell of the mobile station• May also carry short user packets

3. PCH - Paging Channel• It is a downlink channel• Used to carry control information to a mobile station when

the system does not know the location cell of the mobile station

• It is used to inform the mobile station of incoming calls


4. RACH – Random Access Channel• It is an uplink channel • Used to carry control information• It is used for initiating a call (initial access to the serving BS)• It may also carry short user packets• must be heard from the whole desired cell coverage area


Uplink Physical channels

Dedicated Physical Data Channels

(Uplink DPDCH)

Dedicated Physical Control Channel

(Uplink DPCCH))

Physical Random Access Channel (PRACH)

Common Physical ChannelsDedicated Physical Channels

Uplink Physical Channels [1]

1. PRACH - Physical Random Access Channel• It is used to carry RACH• Its transmission is based on Slotted ALOHA approach with

fast acquisition indication• A UE can start the transmission at a number of well-defined

time-slots called access slots• Consist of one or several preambles of length 4096 chips and

a message of length 10 or 20 ms

Common Uplink Physical Channel [1]PRACH

Radio frame: 10ms Radio frame: 10ms5120 Chips

Random Access TransmissionAccess Slot #0




Access Slot #14

#0 #1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13 #14

RACH access slot numbers and their spacing

Common Uplink Physical Channel [2]PRACH

Access Preamble

Control Part

Data Part

Message Part0P 1P

jP

1,2)(N msec 10*N 4096 chips

Structure of the random access transmission

Common Uplink Physical Channel [3]

PRACH


Dedicated Uplink Physical Channel1. DPDCH - Dedicated Physical Data Channel• Used to carry dedicated data i.e. the dedicated transport channel (DCH)• There may be zero, one, or several uplink DPDCHs

2. DPCCH – Dedicated Physical Control Channel• Used to carry control information consists of:

– pilot bits to support channel estimation– transmit power-control (TPC) commands– feedback information (FBI)– an optional transport-format combination indicator (TFCI)

• One DPCCH and up to six parallel DPDCHs can be transmitted simultaneously

ONE

DPDCH &

DPCCH


K determines the number of bits per uplink DPDCH/DPCCH slot

spreading factor SF:

SF = 256/2k

DPDCH spreading factor may thus range from 256 down to 4

Slot #0 Slot #1 Slot # i Slot #14

1 Radio Frame: Tf= 10ms

DPDCH &

DPCCH


DPDCH &

DPCCH

Uplink Channelization CodesDPDCH

& DPCCH

Spreading for uplink DPCCH and DPDCH

I+jQ

Slong, n or Sshort,n

Q

j

DPDCH

DPCCH

DPDCH– Cch,SF,k (k = SF/4)

DPCCH – Cch,256,0

I

Dedicated Physical Channel (Downlink DPCH)A time multiplex of a downlink DPDCH and a downlink DPCCH

Primary Common ControlPhysical Channel(P-CCPCH)

Secondary Common ControlPhysical Channel (S-CCPCH)

SynchronisationChannel(P-SCH & S-SCH )

Acquisition IndicationChannel(AICH)

Page IndicationChannel(PICH)

Common Pilot Channel(CPICH)

Common Physical Channels

Downlink Physical Channels [1]


Dedicated Downlink Physical Channels1. DPCH - Dedicated Physical Channel• Time multiplexing of the DPDCH and DPCCH is used in the downlink.• spreading factor SF:

SF = 512/2k

• In the downlink the spreading factors range from 4 to 512, with some restrictions on the use of spreading factor 512 in the case of soft handover.

• The downlink DPDCH consists of QPSK symbols. Each symbol consists of two bits while in the case of uplink the DPDCH consists of BPSK symbol (one symbol corresponds to one bit).

Slot #0 Slot #1 Slot #i Slot #14

1 Radio Frame Tf= 10ms

Frame structure for downlink DPCH

Data Ndata1 bits

Pilot Npilot bits

TFCI NTFCI bits

TPCNTpc bits

Data 2 Ndata 2 bits

DPCCH DPDCH DPCCH DPDCH DPCCH



SF Channel Bit Rate ( ksps)

Channel Bit Rate(kbps)

256 15 30

128 30 60

64 60 120

32 120 240

16 240 480

8 480 960

4 960 1920

QPSK modulation

1. CPICH - Common Pilot Channel• It is a fixed rate channel carries a pre-defined bit/symbol sequence• Aids in channel estimation to the terminal


Pre-defined symbol sequence

Tslot = 2560 chips, 20 bits = 10 symbols


Common Downlink Physical Channels [1]

Primary CPICHSame channelization code always usedScrambled using primary scrambling codeOne per cellBroadcast over entire cell

2. P-CCPCH - Primary Common Control Physical Channel• Used to carry BCH• SF=256• P-CCPCH is not transmitted during first 256 chips

Frame structure for Primary Common Control Physical Channel

(Tx OFF)


Tslot = 2560 chips, 20 bits

256 chips

Data 18 Bits



3. S-CCPCH - Secondary Common Control Physical Channel• Used to carry FACH and PCH• SF = 256/2K • FACH and PCH can be mapped to same secondary CCPCH• Primary CCPCH has fixed pre-defined rate while secondary CCPCH has

variable rate• Primary CCPCH is continuously transmitted over entire cell while

secondary CCPCH is only transmitted only when there is data available 4. P-SCH Primary Synchronisation Channel

– Carries a unique code (Primary Synchronization Code PSC) which is used in all UMTS cells around the world.

5. S-SCH Secondary Synchronization Channel– Carries a “sequence of 15 secondary synchronization codes which depends on the

Scrambling Code Group of the cell.


6. AICH – Acquisition Indicator Channel• Used to carry Acquisition Indicators (AI) in response to PRACH Preamble

7. PICH – Page Indicator Channel• Used to carry Page Indicator (PI)• PICH is always associated with a S-CCPCH to which PCH is mapped


Cell Search and Initial Access

The initial Cell Search is carried out in three steps:

Step 1: Slot synchronisation - using the primary synchronisation channel.

Step 2: Frame synchronisation and code-group identification using the secondary synchronisation channel.

Step 3: Scrambling-code identification-identified through symbol-by-symbol correlation over the primary CCPCH with all the scrambling codes within the code group.

Structure of Primary and SecondarySynchronisation Channels (SCH)

cp Primary Synchronisation Code ( It is the same for every cell in the system)

cs i,k Secondary Synchronisation Codes ( Where i=0,1….63 is the number of the scrambling

code group, and k= 0,1,…14 is the slot number. Each code is chosen from a set of 16 different codes of length 256).

2560 chips

One 10 ms SCH radio frame

acsi,1

acp

Slot #0 Slot #1 Slot #14

acp

acsi,14

PrimarySCH

acp

acsi,0Secondary

SCH 256 Chips

Fast Cell Search

Downlink primary scrambling codes

Scrambling Code Group 0• SC 0• ----• SC7

Find the Exact SC of cell

Only 8 Possibilities Using P-CPICH

Find Out the SC group #

Only 64 possibilities Using S-SCH

Initial Cell Search

15

15

scramblingcode group

group 00

group 01

group 02

group 03

group 05

group 04

group 62

group 63

1 1 2 8 9 10 15 8 10 16 2 7 15 7 16

1 1 5 16 7 3 14 16 3 10 5 12 14 12 10

1 2 1 15 5 5 12 16 6 11 2 16 11 12

1 2 3 1 8 6 5 2 5 8 4 4 6 3 7

1 2 16 6 6 11 5 12 1 15 12 16 11 2

1 3 4 7 4 1 5 5 3 6 2 8 7 6 8

9 11 12 15 12 9 13 13 11 14 10 16 15 14 16

9 12 10 15 13 14 9 14 15 11 11 13 12 16 10

slot number0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

11

11 11

11 11

11 11

11 11

15

15

15

15 15

15

15

15 15

15 15

5

5

I monitor the S-SCH

Power Control

Power Control [1] 3. Open loop power control

The open loop power control is used to adjusts the transmit

power of the Physical Random Access Channel.

Power Control [2]

Downlink Power control1. Inner loop power control

The downlink inner loop power control adjusts the base station transmit power in order to keep the received downlink SIR at a given SIR target.

2. Outer loop

The outer loop adjusts the SIR target used by the inner loop power control. The SIR target is independently adjusted for each connection based on the estimated quality of the connection. Typically a combination of estimated bit error rate and frame error rate is used for the quality estimate.

UE2

UE1

Power Control [3]

Uplink Power control1. Inner loop power control

The uplink inner loop power control adjusts the MS transmit in order to keep the received uplink SIR at a given SIR target.

Power Control Commands to the mobiles

P1

P2

Keep Received Power Level P1 and P2 Equal

RNC

Power Control [4]

UE

Power Control [5]

2. Outer loopThe outer loop adjusts the SIR target used by the inner loop power control. The SIR target is independently adjusted for each connection based on the estimated quality of the connection.

Outer Loop Power ControlIf quality<target. Increase SIR Target

Frame Reliability info

SIR Target Adjustments Commands

BS Fast Power ControlIf SIR < SIR Target. Send *Power Up* Command

RNC

Mobile stand still

SIR target

Time

Mobility & Handover

Handovers [1]

1. Intra-frequency HO

2. Inter-frequency HO

3. Inter System HO

•Soft•Softer•Hard

•Hard

•Hard

Handover TypesSoft Handover

• In DCH mode, MS has concurrent traffic connections with two BS’s

Softer Handover• Similar to Soft Handover, but between two sectors of the same cell

Inter-Radio Access Technology (IRAT) Handover• CS Handover from a WCDMA system to another system• Traffic and Control Channels are Disconnected and must be Reconnected (hard handover)

Inter-frequency Handover (IFHO)• When the MS must change WCDMA carrier frequency during the Handover• Traffic and Control Channels are Disconnected and must be Reconnected (hard handover)

Inter-RAT Cell Change• Manages PS UE mobility between cells using WCDMA RAN and cells using GSM/GPRS

Cell Reselection• Manages UE mobility between WCDMA cells with same frequency, different frequency and between WCDMA cells and

GSM/GPRS cells, when the UE is in idle mode or CELL_FACH state

WCDMA Handover Scenarios

RNS

RNC

RNS

RNC

Node B Node B Node B Node B

Iu Iu

Iur

Iub IubIub Iub

Inter-Node(Soft)

Intra-Node(Softer)

Inter-RNS(Soft with Iur;

Hard with no Iur)

UTRAN

Core Network

Soft Handover Key Points

• When fast power control is used, soft handover is essential– Allows MS to operate in most conservative power

control mode

• Soft handover provides performance benefits– “Seamless” coverage at cell fringes– Handover may be less noticeable to the user

• Soft handover also degrades system capacity– Uses redundant physical layer resources from adjacent

or overlapping cells

Handover

WCDMA With and Without SHO

time

Trouble zone: Prior to Hard Handover, the MS causes excessive interference to BS2

BS2 Receive Power Target

UE responding to BS1power control bits

UE responding to BS2power control bits

time

BS1 Receive Power Target

Handover

Measurement Handling

MeasurementHandling

RNC

MeasurementControl

Message• List of cells to measure on• Measurement criteria

• Active set (SHO)• Monitored set (cells measured by UE but which does

not belong to active set (Intra/Inter frequency and Inter-RAT frequencies)

MeasurementReport with EVENT

Handover

Measurement Reporting

1. Measure2. Filter3. Apply quality offsets to cells individualOffset4. Compare with measurement criterion5. Send measurement report with EVENT (if occurred)

f1 f1f2

Handover

WCDMA Soft Handover Process

• One finger of the RAKE receiver is constantly scanning neighboring Pilot Channels.

• When a neighboring Pilot Channel reaches the t_add threshold, the new BS is added to the active set

• When the original Base Station reaches the t_drop threshold, originating Base Station is dropped from the active set

Monitor Neighbor BS Pilots Add Destination BS Drop Originating BS

Handover

Soft Handover Add/Drop/Replace• Soft Handover Measurement and Decision

Cell 1 Connected

Add Cell 2Replace Cell 1

with Cell 3

time

Drop Cell 3

EC / N0

Cell 1

Cell 2

Cell 3

T_ADD

T_REPLACE

t t t

T_DROP

Handover

Event 1a, Primary CPICH enters Reporting Range

Event cause:Radio Link addition / replacement due to measurements related to best cell in Active Set

Event 1a and 1b

reportingRange1ahysteresis1atimeToTrigger1a

UE sends Measurement Report message for EVENT 1a and the cell is added to AS. If AS is full maxActiveSet, the cell will replace the worst cell in the current AS, provided the reported cell has better quality

Handover

http://cpi.al.sw.ericsson.se/alexserv?UZ=cpi.al.sw:9230&ID=17173&DB=4697-rancpip2_1ga.alx&ac=image&fn=75_1551-HSD10102_1Uen.B1-u0000046B.pdf

Event 1b, Primary CPICH leaves Reporting Range

Event cause:Radio Link removal from due to measurements related to best cell in Active Set

Event 1a and 1b

reportingRange1bhysteresis1btimeToTrigger1b

UE sends Measurement Report message for EVENT 1b and the cell is removed from the AS (one cell is always kept in AS to maintain connection).

Handover


Event 1c, non-active Primary CPICH becomes better than active Primary CPICH

Event cause:Radio Link substitution due to measurements related to least good cell in AS while the AS is full

hysteresis1ctimeToTrigger1c

UE sends Measurement Report message for EVENT 1c and the cell replaces the least good cell in the AS.

Event 1c

Handover


Event 1d, Change of Best Cell

Event cause:ANY cell (AS or monitored) becomes better than the current best cell in the AS.

hysteresis1dtimeToTrigger1d

UE sends Measurement Report message for EVENT 1d. If the cell already belongs to AS, no action is taken by RNC. Else, the cell will be added to the AS, and if the AS is full, the least good cell will be replaced.

Event 1d

Handover


SRNCSRNC” Measurement Control”

” Measurement Report”

(BCCH/DCCH)

(DCCH)

RNCEvaluation

Perform Measurement

UE Evaluation

Execution

Radio LinkAdd/Removal/Replace

”Active Set Update” (DCCH)

Radio Link Add/Removal/Replace

”Active Set Update Complete” (DCCH)

Radio LinkAdd/Removal/Replace

RNCEvaluation

”Measurement Control” (DCCH)

Signaling Flow in SHO

Handover

Compressed Mode• The physical channel is reconfigured to create transmission and

reception gaps.• UE then tunes to other frequencies (GSM) to conduct measurements• Signaling required to prepare for the measurements

– Additional UE and network processing load• Recommendation:

– Minimise time in compressed mode– Avoid going in and out of compressed mode

Handover

Decreasing the Spreading Factor by

2:1

• Increases Data Rate so bits get through twice as fast!

Puncturing bits

• weakens FEC coding

Higher layer scheduling

• Reduces available timeslots for user traffic

Data compression can be accomplished by:

Instantaneous Rate/Power

Downlink slotted transmission

Tf

Normal transmission Slotted transmission

Idle period available forinterfrequency measurement

Compressed Mode

Compressed Mode

• Using slotted downlink transmission mode, a single-receiver mobile station can carry out measurements on other frequencies without affecting its normal data flow.

• The information normally transmitted during a 10ms frame is compressed in time, either by code puncturing or by reducing the spreading factor by a factor of 2.

• As a result, an idle time period of 5ms is created within each frame. During this time, the MS receiver is idle and can be used for inter-frequency measurements.

HO Triggering Thresholds set in RNCHO Triggering Thresholds set in RNC

Event Triggered HOreasons fulfilled in RNC

Event Triggered HOreasons fulfilled in RNC

RNC commands selected UE(s) to startIF/IS measurements

RNC commands selected UE(s) to startIF/IS measurements

Measurements are done in Compressed Mode (CM)

Measurements are done in Compressed Mode (CM)

UE reports best GSM cells (RSSI) to RNCUE reports best GSM cells (RSSI) to RNC

RNC makes HO decision andcommands UE to target cellv

RNC makes HO decision andcommands UE to target cellv

BSIC verification for GSM cellsBSIC verification for GSM cells

UE reports best UMTS cells (Ec/Io; RSCP) to RNC

UE reports best UMTS cells (Ec/Io; RSCP) to RNC

Compressed Mode (for IFHO and ISHO)

Steps during

Inter Frequency Handoverand

Inter-system Handovers

Only in ISHOOnly in ISHO

Both IFHO and ISHOBoth IFHO and ISHO

High Speed Downlink Packet Access(HSDPA)

Introduction

• In order to meet the increasing demand for high data-rate multimedia services, the 3rd Generation Partnership Project (3GPP) has released a new high-speed data transfer feature named High-Speed Downlink Packet Access (HSDPA).

• It offers peak data rates of up to 14 Mbps, resulting in a better end-user experience for downlink data applications, with shorter connection and response times.

• HSDPA improves the use of streaming applications and Web browsing applications.

Key Features

Short physical layer frames

Adaptive Modulation and Coding (AMC)

Fast Hybrid-ARQ Fast scheduling Fixed SF =16

HSDPA can be seen as an extension of the DSCH with new features such as:

HSDPA Operation

New Channel Structure

1. HS-DSCH – High Speed Downlink Shared Channel

• It is the primary radio bearer• HS-DSCH can be shared between users in the time domain• Transmission Time Interval consists of three time slots (2ms)

to shorten round trip delays• Constant spreading factor of 16• Maximum of 15 parallel codes allocated

2. HS-SCCH – High Speed Shared Control Channel• Carry download signaling information in the downlink direction• Transmitted before each scheduled TTI• Has a duration of 3 time slots• Multiple HS-SCCH can be configured to support parallel HS-DSCH

transmissions• A UE can be allocated a maximum of 4 HS-SCCH

UE-ID (H-RNTI) Channelization Code Set

Modulation Scheme

TB Size Redundancy Version

HARQ Process Indicator

Figure : HS-SCCH and HS-DSCH timing relationship

Part 1 Part 2

Downlink DCH (DPCCH/DPDCH)

1 Slot

1 Slot

Codes to receive

HS-SCCH

HS-DSCH

3. HS-DPCCH – High Speed Dedicated Physical Control Channel

• Carry ACK/NACK information and link quality information in the uplink direction

• This information is used by Node B scheduler to determine the destination terminal and transmission data rates to be used

• Consist of two parts:• Part I: ACK/NACK transmission• Part II: Downlink Channel Quality Indicator (CQI) to indicate;

– estimated transport block size– modulation type– number of parallel codes

CQI (N) ACK

Figure: HSDPA Channel operation

HS-DPCCH: CQI

HS-SCCH: DL Transfer Information

HS-DSCH: Data Transfer

HS-DPCCH: ACK / NACK UE

Summary of HSDPA Channels

Adaptive Modulation and Coding• Continuously optimizing

– the code rate– modulation scheme– number of codes employed – transmit power

• QPSK and 16 QAM• Code rates: ¼ to ¾ • Based on channel quality reported on CQI• Users experiencing favorable channel conditions will be allocated higher

data rates• A single user can receive up to 10.8 Mbps peak data rates• Maximum data rate specified in HSDPA is 14.4 Mbps

QPSK16 QAM


Adaptive Modulation and CodingAdaptive

Modulation and Coding (AMC)

Modulation coding

rate

Data rate

(1 code)

Data rate

(5 codes)

Data rate

(15 codes)

QPSK 1/4 120kbps 600kbps 1.8Mbps

QPSK 1/2 240kbps 1.2Mbps 3.6Mbps

QPSK 3/4 360kbps 1.8Mbps 5.4Mbps

16QAM 1/2 480kbps 2.4Mbps 7.2Mbps

16QAM 3/4 720kbps 3.6Mbps 10.8Mbps

Hybrid ARQ Fast Hybrid-ARQ

Advantage: improve transferring reliabilityDisadvantage: lower utilization in bad channel state

Advantage: good performance in lower Bit Error Rate (BER)Disadvantage: bad performance in high BER

FECARQ

HARQ

Combine FEC and ARQ, each sending packet includes error detection bit and error correction bit

Packet A confirm

Packet A confirm

Error packet A

Packet A

Packet A

Error packet A

Packet A

Packet A missing data

Packet A missing data

HARQ phase I（ Resending is in RNC， R99）

HARQ phase II, III（ Resending is in Node B, HSDPA）

Packet A

Discard Reserve

Resend whole packet Resend data

Soft combination

Resend requirement

Resend requirement

Packet BPacket B

Send SendReceive Receive

Lower efficiencyLonger time delay

Higher efficiencyShorter time delay

Hybrid ARQ• Hybrid Automatic Repeat request• Stop and Wait (SAW) protocol• HARQ allows the UE to request retransmission• HARQ is implemented at MAC-hs (Media Access Control high

speed) terminated at Node B• With HARQ UE does not discard the erroneous energy• UE stores it and later combines with retransmission (Soft

Combining)

Fast Hybrid-ARQ

Chase Combining

• Retransmitting same information

Incremental Redundancy

• Different redundancy information can be send during re-transmission

Fast Packet Scheduling (1)

• the scheduler is located at the Node B as opposed to the RNC• this enables the scheduler to quickly track the UE channel condition and

adapt the data rate allocation accordingly• Several algorithms can be used for the scheduler such as:

1. Round Robin (RR)• a first-in first-out approach• provides a high degree of fairness• users can be served even when they are experiencing weak signal

lowering the overall system throughput

Fast scheduling

2. Maximum Carrier to Interference (C/I)• schedules users with the highest C/I during the current TTI• highest system throughput• no effort to maintain any kind of fairness

3. Proportional Fair• Good trade-off between RR and maximum C/I• schedules users according to the ratio between their

instantaneous achievable data rate and their average served data rate

Fast Packet Scheduling (2) Fast scheduling

Physical Layer Procedures

STEP I: Scheduler at Node B evaluates for different users:– the channel conditions– Pending data in buffer– Time elapsed since last served– Pending retransmissions

STEP II: Once a terminal is selected, Node B checks for:– The available codes– Type of modulation can be used– Terminal capability limitations

STEP III: Node B starts to transmit HS-SCCH two slots before HS-DSCH TTISTEP IV: MS monitors HS-SCCH and decodes Part I and Part II of HS-SCCHSTEP V: MS then use this buffered information to decode HS-DSCHSTEP VI: Upon detecting this combined data, MS send ACK/NACK in the uplink

direction depending on the CRC results

Figure: Terminal timing with respect to one HARQ process

HS-SCCH

HS-DSCH

HS-SCCH

N Slots7.5 slots (approx)

Downlink transmission

Uplink transmissionHS-DPCCH (ACK / NACK + Feedback )

CRC result

HSDPA device categories

CQI Table (for category 1 to 6)CQI value Transport

Block SizeNumber of HS-PDSCH Modulation

Reference power adjustment

NIR XRV

0 N/A Out of range1 137 1 QPSK 0 9600 0

2 173 1 QPSK 0

3 233 1 QPSK 0

4 317 1 QPSK 0

5 377 1 QPSK 0

6 461 1 QPSK 0

7 650 2 QPSK 0

8 792 2 QPSK 0

9 931 2 QPSK 0

10 1262 3 QPSK 0

11 1483 3 QPSK 0

12 1742 3 QPSK 0

13 2279 4 QPSK 0

14 2583 4 QPSK 0

15 3319 5 QPSK 0

16 3565 5 16-QAM 0

17 4189 5 16-QAM 0

18 4664 5 16-QAM 0

19 5287 5 16-QAM 0

20 5887 5 16-QAM 0

21 6554 5 16-QAM 0

22 7168 5 16-QAM 0

23 7168 5 16-QAM -1

24 7168 5 16-QAM -2

25 7168 5 16-QAM -3

26 7168 5 16-QAM -4

27 7168 5 16-QAM -5

28 7168 5 16-QAM -6

29 7168 5 16-QAM -7

30 7168 5 16-QAM -8

CQI Table (for category 11 & 12)CQI value Transport Block

SizeNumber of HS-PDSCH Modulation

Reference power adjustment

NIR XRV

0 N/A Out of range1 137 1 QPSK 0 4800 0

2 173 1 QPSK 0

3 233 1 QPSK 0

4 317 1 QPSK 0

5 377 1 QPSK 0

6 461 1 QPSK 0

7 650 2 QPSK 0

8 792 2 QPSK 0

9 931 2 QPSK 0

10 1262 3 QPSK 0

11 1483 3 QPSK 0

12 1742 3 QPSK 0

13 2279 4 QPSK 0

14 2583 4 QPSK 0

15 3319 5 QPSK 0

16 3319 5 QPSK -1

17 3319 5 QPSK -2

18 3319 5 QPSK -3

19 3319 5 QPSK -4

20 3319 5 QPSK -5

21 3319 5 QPSK -6

22 3319 5 QPSK -7

23 3319 5 QPSK -8

24 3319 5 QPSK -9

25 3319 5 QPSK -10

26 3319 5 QPSK -11

27 3319 5 QPSK -12

28 3319 5 QPSK -13

29 3319 5 QPSK -14

30 3319 5 QPSK -15

HSDPA Protocols

Mobility

• UTRAN determines the serving HS-DSCH cell for an HSDPA-capable UE• A new measurement event is defined• measurement basically reports the best serving HS-DSCH cell to the

serving RNC based on a measurement of the P-CPICH Ec/I0• serving RNC sends a synchronised radio link reconfiguration prepare

message to the Node B• At a specified time index, the source cell stops transmitting to the

user• MAC-hs packet scheduler in the target cell is thereafter allowed to

control transmission to the user• PDUs for the user are moved from the MAC-hs in the source cell to

the MAC-hs in the target cell during the HS-DSCH handover

High Speed Uplink Packet Access(HSUPA)

Key Features

• Fast HARQ terminated at Node B

• Fast Node B based uplink scheduling

• Higher order modulation

UE

Fast Hybrid ARQ• Fast HARQ is to allow the Node B to ask for the UE to retransmit the uplink packet if it

was not received correctly• One Node B received a packet correctly but other didn’t.• Due to limited UE power the UE may not be able to transmit at the same data rate

incase of retransmission

RNC

Node B

UE

PacketRLC ACK/NACK

Retransmission

Rel ‘99 Uplink DCH

RNC

Node B

Packet

Retransmission

L1 ACK/NACK

Uplink E-DCH

Correctly Received Packet

Combining of Packets

Fast Packet Scheduling• The uplink scheduling is Node B based• Node B gives UE a set of data rates based on uplink load measurements

RNC

Node B

Traffic volume measurement

TFC Control

Data transmission

Rel ‘99 Uplink DCH

RNC

Node B

UE

Scheduling info

Data transmission

Scheduling Assignment

Uplink E-DCH

UE

HSUPA device categories

Physical Channels1. E-DPDCH – Enhanced Dedicated Physical Data Channel

• used to carry the E-DCH user data• There may be zero, 1, 2 or 4 E-DPDCH on each radio link• SF = 256 , 128, 64 , 32 , 16 , 8 , 4, 2

2. E-DPCCH – Enhanced Dedicated Physical Control Channel• used to transmit control information associated with the E-

DCH• There is at most one E-DPCCH on each radio link• E-DPDCH and E-DPCCH are always transmitted

simultaneously

Slot #0 Slot #1 Slot # i Slot #14

E-DPDCH Frame Structure

Data Slot #2

1 Sub frame = 2 ms

Message part Radio Frame TRACH Tf = 10msControl

Data Ndata bits

10 Bits

E-DPDCH

E-DPCCH

Tslot = 2560 chips, Ndata = 10*2k bits (k = 0...7)

Tslot = 2560 chips

3. E-RGCH – E-DCH Relative Grant Channel• It is a fixed rate (SF=128) dedicated downlink physical channel• Indicates to the UE whether to increase, decrease or keep unchanged the

transmit power level of the E-DCH • UP , DOWN or HOLD commands

4. E-HICH - E-DCH Hybrid ARQ Indicator Channel• It is a fixed rate (SF=128) dedicated downlink physical channel• carry the uplink E-DCH hybrid ARQ acknowledgement indicator

5. E-AGCH - E–DCH Absolute Grant Channel• It is a fixed rate (30 kbps, SF=256) downlink physical channel• Provides an absolute power level above the level for the DPDCH

(associated with a DCH) that the UE should adopt

Figure: New physical channels introduced by HSUPA

E-HICH

E-RGCH, E-AGCH

E-DPCCH

E-DPDCH

HARQ

Uplink Scheduling

C-Plane

U-PlaneUE

HSUPA Protocols

Comparing HSDPA and HSUPAFeature HSDPA HSUPA

Peak Data Rate 14.4 Mbps 5.6 Mbps

Modulation Scheme (s) QPSK, 16QAM QPSK

TTI 2ms 2ms (optional) / 10ms

Transport Channel Type Shared Dedicated


Yes No

HARQ HARQ with incremental redundancy; Feedback in HS-DPCCH

HARQ with incremental redundancy; Feedback in dedicated

physical channel ( E-HICH)

Packet Scheduling Downlink Scheduling (for capacity allocation)

Uplink Scheduling (for power control )

Soft Handover Support ( U-Plane) No(in the Downlink

Yes

Part 1 fundamentals of 3 g

Engineering

Transcript of Part 1 fundamentals of 3 g