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Rio De Janeiro October 2006

UMTS OVERVIEW Maria Stella Iacobucci

The UMTS radiomobile system

Maria Stella Iacobucci

2 Rio De Janeiro October 2006


I’m grateful to TELECOMITALIA colleagues for havingprovided some of the slides of this presentation





Divertissement



Timeline

Standardization aspects

UTRAN: UMTS Terrestrial Radio Access Network

The Code Division Multiple Access

Handover

UMTS Radio Interface

Logical, Physical and Transport Channels

An Introduction to UMTS Radio Protocols

An Introduction to Radio Access Bearers Physical Level Procedures

UMTS Security

The UMTS Evolution: HSDPA





Standardization Aspects



“UMTS will be a mobile communications system that can offer

significant user benefits including high-quality wireless multimedia

services to a convergent network of fixed, cellular and satellite

components.

It will deliver information directly to users and provide them with

access to new and innovative services and applications.

It will offer mobile personalised communications to the mass market

regardless of location, network and terminal used”.

UMTS Forum 1997





UMTS/IMT-2000 systems had to be truly innovative interms of performances and offered services

UMTS/IMT-2000 GOALS

Reflections on radio access and networks choices



Standardization bodies

In 1995, ETSI starts the activity on 3G systemsIn January 1998, the radio interface was :

W-CDMA in the “paired bands” (FDD Mode)

TD-CDMA in the “unpaired bands” (TDD Mode)

In Decemberer 1998, the standardization bodies of Europe, Japan, Koreaand USA create the 3GPP (3rd Generation Partnership Project); later even thechinese CWTS reached the 3GPP

Inside the ITU, the 3G system is called IMT-2000; IMT-2000 includes MC-CDMA, EDGE and UMTS.





3G Variants

PDC Advanced GSMNSS and packetcore

WCDMA 3G (Japan)

GSM 900/1800 Advanced GSMNSS and packetcore

WCDMA, GSM,EDGE

3G (Europe)

IS-95,GSM1900,TDMA

IS-41WCDMA, EDGE,WCDMA2000

3G (US)

2G basisSwitchingRadio Access

Variant



UMTS Frequency Allocation

The CEPT/ERC recommendation n° 07/1997 allocates to

terrestrial UMTS the bandwidths of 1900-1980 MHz, 2010-

2025 MHz and 2110-2170 MHz

Inside the ERC recommendation n° 25/1999, the usage of

each band is specified as follows:• FDD bandwidths: 1920-1980 MHz e 2110-2170 MHz

• TDD bandwidths: 1900-1920 MHz e 2010-2025 MHz

An “unlicensed” bandwidth for “Self provided applicationsoperating in a self-coordinating mode in shared spectrum” is

2010-2020 MHz





1900 1980 2010 2025 2110 2170 22001920

T

D D

F

D D

S A T

F

D D

S A T

T

D D

UMTS bandwidths: European Situation

215 MHz assigned

• 155 MHz terrestrial component:

• FDD 60 + 60 MHz

• TDD 35 MHz

• 60 MHz satellite component

T D D

T D D (private usage)

FDD

SAT



The migration towards UMTS

GSMGSM

HSCSDHSCSD

GPRSGPRS

EDGEEDGE

UMTSUMTS

NONO

UMTSUMTS





UMTS: general aspects

Iu

UTRAN

UE

Uu

UTRAN UMTS Terrestrial Radio

Access Network

CN Core Network

UE User Equipemet

CN



UTRAN Architecture





UTRAN: UMTS Terrestrial Radio Access Network



Network Elements are grouped in:

• UTRAN, that controls radio interface functionalities

• Core Network (CN), that routes the traffic

• User Equipment (UE) is divided in:

• Mobile Equipment (ME), which principal functions are:

• UMTS Subscriber Identity Module, a smartcard that

•Contains the user identity and a copy of the service profile

•Stores the authentication algorithms, authentication and

encryption keys

UTRAN elements: User Equipment





UTRAN elements: Node B

Node B (Radio Base Station) groups one or more Base Transceiver

Stations and plays the following functions:

• Radio Interface Processing (channel coding, interleaving,

spreading, mo-demodulation, transmission and reception)

• downlink parameters measurements (BER, received power) and

transmission to the node B

• Execution of access, authentication, hand-over procedures



UTRAN elements: RNC

Radio Network Controller (RNC) principal functionalities are:

• Node B Radio Resource Control

• Codes allocation and radio link setup

•Packet scheduling and retransmission

•Admission Control and congestion monitoring

•Signalling and user data processing

•Handover decision

•Outer loop power control





UTRAN elements: Iub, Iur and Iu interfaces

• Iub is a proprietary interface and connects a node B to

an RNC

• Iur has special functions fo handover and macro-

diversity; is a standard interface

•Iu, which connects the RNC with the Core Network is an

“open multivendor” interface

•The protocols on such interfaces are ATM based



Code Division Multiple Access





Radio Access Techniques

P Power

T TimeF Frequency

PP

TT

PP

TT

FF

PP

TT

FF

FDMA (TACS)FDMA (TACS)

TDMA (GSM, DECT)TDMA (GSM, DECT)

CDMA (UMTS)CDMA (UMTS)

FF

TDMA/CDMA (UMTS)TDMA/CDMA (UMTS)



Code Division Multiple Access

The separation among different users that share the same radio resourceis based on the use of orthogonal codes

It is not a slotted access technique!

Three variants:

Direct Sequence (DS): is based on the direct modulation of datasthrough a given code sequence

Frequency Hopping (FH): is based on hops of the carrier which follows a

given hop sequence Time Hopping (TH): is based on hops of the pulses in time following a

given time hopping sequence





A beautiful mind

Two pages from Lamarr and Antheil patent, 1942



The actress and composer invention





Code division multiple access

Λαλοι συ την

Ηλλενικην

γλωσσαν?

Esta es la tierra

nadàl de mi

hermano

Sagunto...

Je suis Ivorien…

est-ce que voi

connaissez mon

pays?



frequency

code

time

DS-CDMADirect Sequence - Code Division Multiple Access

Wide spectral occupation

Complex receiver to recover the information

Stringent power control

No frequency planning (reuse factor = 1)





Spreading and despreadingNarrowband interfering signal

f

f

f

f

f

S(f)

Information signal of Bnbandwidth

Information signal of expanded

bandwidth Bw

expanded information signalplus narrowband interferingsignal at the receiver input

Signals after the despreading

Signals at the receiver output



Spreading and despreadingBroadband interfering signal

f

f

f

f

f

S(f)

Information signal of Bnbandwidth

Information signal of expanded

bandwidth Bw

expanded information signalplus broadband interferingsignal at the receiver input

Signals after the despreading

Signals at the receiver output



29 UMTS OVERVIEW Maria Stella Iacobucci

Chip sequence

t

t

t

Informationsequence

Transmittedsequence

x

Single Transmission

b(t)

x(t)b(t)c(t)

c(t)

x(t)


Chip sequence

t

Receivedsequence

Decodedsequence

Single Reception

t

b(t)

c(t)c(t)x b(t)z(t)

c(t)

t

z(t)=x(t)





Orthogonal Sequences

t

c1(t)

Chip sequence1

c1(t) ·c2(t)

t

c2(t)

Chip sequence2

t∑

chip N

chip N 1

1 = 0

Nchip=8



t

Multiple transmission

c1(t)

x1(t)

tb1(t)

t

x2(t)

tb2 (t)

c2(t)





Multiple Access

t

x1(t)+x2(t)

x1(t)x2(t)



Multiple reception

t

z(t)=x1(t)+x2(t)

t

c1(t)

z(t) ·c1(t)

t

b1(t)

t

∑chip

N

chip N 1

1





In formulas

[ ] [ ]

[ ] [ ]

[ ] [ ]

[ ] [ ]

[ ] [ ] )()()()()()()(

)()()()()()()()(

)()()()()()()(

)()()()()()()()(

Decoding

)()()(

AccessMultiple

)()()(

)()()(

Coding

0)()(;1)()(

Property

2222211

2222112

1122111

1221111

21

222

111

21

t xt ct c E t xt ct c E t x

t ct ct xt ct ct x E t ct z E

t xt ct c E t xt ct c E t x

t ct ct xt ct ct x E t ct z E

t xt xt z

t ct bt x

t ct bt x

t ct c E t ct c E

bb

bb

bb

bb

bb

T T

T T

T T

T T

T T ii

=⋅⋅+⋅⋅=

=⋅⋅+⋅⋅=⋅

=⋅⋅+⋅⋅=

=⋅⋅+⋅⋅=⋅

+=

⋅=

⋅=

=⋅=⋅



Spreading Sequences

The more used families for spreading sequences are:

• pseudo noise sequences, PN, with pseudo-noise caracteristics but notperfectly orhtogonality

• In UMTS Gold and Kasami codes are used, with good cross-correlation properties

• In UMTS are used for scrambling codes

• Perfect orthogonal sequences, with no good spectral and cross-correlationproperties, but with perfect orthogonality

• In UMTS are used for spreading codes





Spreading codes

SF = 1 SF = 2 SF = 4

C2,1 = (1,1)

C2,2 = (1,-1)

C1,1 = (1)

C4,1 = (1,1,1,1)

C4,2 = (1,1,-1,-1)

C4,3 = (1,-1,1,-1)

C4,4 = (1,-1,-1,1)



Spreading and Scrambling

In UMTS, a code assigned to a user is given by the product of a scramblingand a spreading code

Uplink Scrambling codes distinguish different users

Spreading codes distinguish different communications associated to the sameuser

Separation of data and control channels

No code planning: in uplink there are millions of available codes

Downlink Scrambling codes distinguish different cells

The number of downlink scrambling codes is 512

Spreading codes are associated to different users into the same cell





Spreading and scrambling codes

No, do not increases the

bandwidth

Yes, increases the

bandwidthSpreading

Downlink: 512 codes of 10ms: Gold Codes

OVSFCode family

Downlink: 10ms=38400chips

Uplink: millions

Number of codes related toa scrambling code =spreading factor

Number of codes

Uplink: (1)10ms=38400chips o (2) 66.7µs=256chips

4-256 chips (1.0-66.7µs)for the downlink even 512chips

length

Scrambling codeSpreading code



Principles of Wideband CDMA transmission

Spreading with a code of 256 chip (SF=256)

Spreading with a code of 256 chip

(SF=256)

Spreading with a code of

4 chip (SF=4)

38400 chip ogni 10 ms



Voice source

(8-13 kbit/s)

Packet data: WEB

Browsing and

streaming

(64-144 kbit/s)

High Speed data: videoconference,

videotelephony

(≥ 384 kbit/s)

80 bit

640 bit

3840 bit

Error

correction

coding

Error

correctioncoding

Error

correctioncoding

150 bit

2400 bit

9600 bit





Example: data at 64 kbit/s

64+3,4=67,4 kbit/s

202 kbit/s

240 kbit/s

3,84 Mchip/s

User bit rate + associate signalling

Signal in input at the RF modulator

Convolutional codingRate = 1/3

Rate matching (Bit Stuffing)

Moltilication for the OVSF code of

length (Spreading Factor) = 16



Multimedia in UMTS

38400 chip in 10 ms

(80 voice bits + coding)

38400 chip in 10 ms

(640 data bits + coding)

38400 chip in 10 ms

(3840 bit High Speed + cod.)

The input signals

are distinguished by

codes of different

length

3,840 Mchip/s

Multiple

Access

MultipleAccess

MultipleAccess





CDMA Transmission and reception

DATA

0 f 0 0

BACKGROUNDNOISE

f 0

EXTERNALINTERFERENCE

f 0

OTHER CELL

INTERFERENCE

f 0

OTHER USER

INTERFERENCE

f 0

ENCODING &INTERLEAVINGDATA

CARRIER

PN SOURCE

CARRIER

DIGITALFILTER

PN SOURCE

CORRELATOR

DEINTERLEAVING& DECODING

DATA

WIDEBAND

SPECTRUM

f 0



Propagation channel

The chip duration at 3.84 Mchip/s is 0.26 µs

The delay profile varies, in urban environment, from 1 to 2 µs, even if inhilly zones delays of 20 µs have been observed

If the multipath components do not overlap, the CDMA receiver is ableto coherently recombine the different echoes





Propagation channel effects

In a narrowband system the pulses are long and multipathcomponents overlap

f

t t

τ2τ3τ1

τ1

τ2

τ3



Propagation channel effects

In a broadband system the pulses are shortand multipath components do not overlap.

Because of that, they can be recombined.

f

tt

τ2τ3τ1

τ1

τ2

τ3

τ0

τ0 −τ1

τ0 −τ2

τ0 −τ3

+

t





Spreadingcodes

Σ

Channelestimation

Receiver

Phaserecovery

Rake Receiver

Matchedfilter

Channelestimation

Phaserecovery

∆τ1

∆τnDespreading

Despreading

*baseband

To thedecodingcircuit

Identifies the

correlation

peack and

distributes the

timing

Radio channel

estimationthrough a pilot

sequence

Propagation

delay

compensation

Somma le

componenti

riallineate (MaximalRatio Combining)

Signal S2(t)*from RF



Rake receiver

Rake receiver uses many basebandcorrelators to elaborate and recombinedifferent multipath signal components

Two possible algorithms:equal-gain combining, which assigns thesame weight to each rake finger

maximal-ratio combining, which elaboratesthe finger outputs to estimate the weights thatmaximize the SNR

It is possible to show that if the n multipaths are not correlated, then

Price and Green, 1958

( ) ( )1

i

i

n S S

N N output i =

= ∑





Capacity

For N users, the signal to interference ratio is:

( )

( ) 1 / 1

/

1

1

1

0 −=

−=

−=

−=

N

G

f P N

f P

n

E

N P N

PSNR

c

bb

0 /

1

n E

G N

b

+=



Near-far problem

In general:

If the power is the same for eachsignal, then:

When the user k power is higher,then:

∑=

=+++

= N

i

i N I

C

I I I

C

I

C

1

21 ...

N

G

G

C N

C

I N

C

I

C

i

=

⋅

=⋅

=

( ) ( ) ( )

G

KC I

K N G

I G

C N

C I I N

C I C

k

k k

≡

+−=

+

⋅−

=+⋅−

=1

11




0

5

10

15

20

25

30

35

40

45

50

55

60

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Mobile station power (W)

C a p a c i t y ( c h a n n e l s / M H z / s i t e )

ρ=0

ρ=1, 2

CDMA

ρ=0

ρ=1

ρ=2

GSM half rate (TCH/HS)

GSM full rate (TCH/FS)

ρ = power control errorstandard deviation

Power control effect on capacity



Power Control algorithms

The outer Loop Power Control executes a “fine tuning” of the Inner Loop PowerControl

UE BTS RNC

OPEN LOOP POWER CONTROL

INNER LOOP (FAST) POWER CONTROL (SIR Target) 1.5 KHz

OUTER LOOP POWER CONTROL (BLER Target) 10-100 Hz





Power Control algorithms

• The open loop power control establishes, during set-up, the mobiletransmission power from the path attenuation

• Because UMTS is an FDD system, then uplink and downlink fading processes arenot correlated and therefore the open loop power control is not able tocompensate the downlink fading

• Therefore a closed loop power control algorithm must be established betweenthe MS and the BTS, in order to determine, from the received SNR, the goodtransmission power

• The outer loop power control has the goal to adjust the SNR target value onwhich the closed loop power control is based by measuring the BLER at the RNC



“Closed Loop Power Control” gain

-2

-1

0

1

2

3

4

5

6

7

8

9

0 50 100 150 200 250 300

Mobile speed [km/h]

G a i n

E b

/ n 0

[ d B ]

Canale voce a 8kbps





6 7 8

91011

1213141516 17

1 10 100 1000

velocità del mobile (km/h)

E b / N o [ d B ] @ B

E R = 0 . 1 % Outdoor to indoor A

Outdoor to indoor B

Vehicular A

Vehicular B

Link performances

W-CDMA: voice service (8 kbit/s) - downlink

The “outdoor to indoor” and “vehicular” (A o B) are referred to different

propagation models



1,E-06

1,E-05

1,E-04

1,E-03

1,E-02

1,E-01

1,E+00

4 4,5 5 5,5 6 6,5 7 7,5

Eb/No [dB]

B E R

it. #1

it. #2

it. #3

it. #4

it. #5

it. #6

it. #7

it. #8

TPC Hard

TPC Soft

BLER

Link PerformancesLCD data at 144 kbit/s with turbo code, function of the number of

iteration at the decoder side - Downlink (Vehicular A - 120 km/h)





Cell breathing

C/I @ 1/N

Cell with radius R and N users

Increases the user density:

Cell with radius R and (N+X) users

(C/I)’@ 1/(N+X) < C/I

In the new situation the cell radius must be reduced

to come back to the new C/I

N

N

N+X



Admission Control

During network planning, the target SIR is defined

Each UE that has an active communication consumes a part of the target SIR

The Admission Control decides if new communications can be setup without degrading the existing ones

Without varying the assigned resources

varying the assigned resources





Handover



Handover

GSM

SIST.

TYPE

HardHard

HandoverHandover

BEFORE DURING AFTER

DECT

SeamlessSeamless

HandoverHandover

UMTS

SoftSoft

HandoverHandover

MSC

RNC

F1

BS#1

RFP#1

CCFP

BSS#1

F2

F2

BS#2

RFP#2

BSS#2BSS#2

MSC

F1

BS#2

RNC

F1BS#1

BSS#1BSS#2

MSC

F1

BS#2

RNC

F1

BS#1

RFP#1 RFP#2

CCFP

F1

BSS#1

RFP#2

CCFP

F2

RFP#1

F1





Soft Handover and macrodiversity

CELLA A CELLA B

CELL C

Signal margin

Soft Handover region

“ADD” threshold

Time margin

Ec/No

TIME

“DROP” threshold



Macrodiversity

Macrodiversity consists in having more that one signal belonging to the

same connection, sent to and received from different cells

In uplink, macrodiversity can be handled:

in the node B (softer handover), where the Maximum Ratio Combining (MRC)

technique is used

In the RNC (soft handover), which makes a packet selection, that is packets from

different links carry link quality informations (i.e. C/I) and the RNC chooses each time

the best

In downlink, macrodiversity is always handled with the method of

Maximum Ratio Combining





Spreadingcodes

Σ

Channelestimation

Receiver

Phaserecovery

Rake Receiver

Matchedfilter

Channelestimation

Phaserecovery

∆τ1

∆τnDespreading

Despreading

*baseband


Identifies the

correlation

peack and

distributes the

timing

Radio channel

estimationthrough a pilot

sequence

Propagation

delay

compensation

Somma le

componenti





Rake receiver in macrodiversity

In macrodiversity, the fingers must generate different codes, corresponding to different sectors

Spreadingcodes

Σ

Channelestimation

Receiver

Phaserecovery

Matchedfilter

Channelestimation

Phaserecovery

∆τ1

∆τnDespreading

Despreading

*baseband


Identifies the

correlation

peack and

distributes the

timing

Radio channel

estimation

through a pilot

sequence

Propagation

delay

compensation

Somma le

componenti







Different RNC roles

RNC takes different roles to support macrodiversity:

RNC Serving

RNC Controlling

RNC Drift



RNC roles

RNSRNC Serving and

Controlling

for ARNC

RNS

RNC

Core Network

Node B Node B Node B Node B

Iu Iu

Iur

Iub IubIub Iub

A connection B connection

RNC Drift andControlling

for B





Handover

The UMTS handover is “mobile assisted”, that is:

the MU periodically makes measurements on the downlink channel

Sends such measurements to the RNC, which handles the add-drop of BTSs

If the handover is inter-RNC, one is Serving, and handles the add-drop of BTSs

The serving RNC can change through the SRNS (Serving Radio Network System

Relocation) procedure



RNCRNC

The mobile is connected totwo cells belonging todifferent BTSs

BTS 1BTS 1

BTS 2BTS 2

LC=X

LC=Y

LC = Long Code

Soft Handover





The mobile is connected totwo cells belonging to thesame BTS

LC=X

Sector 1Sector 1

Sector 2Sector 2BTSBTS

LC=Y

LC = Long Code

Softer Handover

RNCRNC



Totally, 10 users in SHOV

• Total number of calls (1 call/user): 30

• Busy channels for each cell: 20

• Total number busy channels : 40

• Percentage of soft handover calls: 10/30 = 33%

• Busy channels/call: 40/30 = 1.33

Cell 1: 10 active link

to Cell 1, plus 5 utenti

in Soft Handover

Cell 2: 10 active link

to Cell 1, plus 5 utenti

in Soft Handover

Soft Handover and channels occupation





Macrodiversity and radio independence

Legacy GSM/GPRS: possibility to re-use the CORE NETWORK architecture

Access

Network

Core networkCore networkUMTSUMTS

Radio Protocols

Radio indipendence

Radio dipendence BTS BTS BTS

RNC RNC



S-RNS Relocation

MSC

Before handover

RNS RNS BSC

MSC

During s-handover

RNS RNS

MSC

After S-RNS relocation

RNS RNSBSC

MSC

after s-handover

RNS RNS

the Serving Radio Network System Relocation procedure moves the Iu interface fromthe old RNS to the new RNS





Handover

Handover types:

intra-system intra-frequency Handover (Soft handover)

intra-system inter-frequency Handover (Hard handover)

Inter-system Handover (i.e. GSM-UMTS)

GSM/GPRS GSM/GPRS GSM/GPRS GSM/GPRS

UMTSMacro F1

UMTSMicro F2

Soft HO

Soft HO

Hard HO

Inter-System HO

UMTSMacro F1

UMTSMacro F1



Inter Radio Access Technology (RAT)Handover

Allows the user to continue a conversation from UMTS to GSM coverage and viceversa

The Handover procedure is handled at the network side on the basis of themeasurement reports sent from the mobile

In the GSM network, the measurement reports are sent every 480 ms

In UMTS is the l’RNC which communicates to the mobile – with a measurement control message – the type of measures and the cell list

In UMTS the reporting is event triggered , to reduce the signaling load





Inter RAT Handover: events

2d event : measurement activation on the GSM/GPRS network

2f event : measurement disactivation on the GSM/GPRS network

3a event : handover evaluation algorithm activation

QualityMeasurement

Event 2d

CPICH A(Quality)

Event 3a Event 2f

GSM Carrier Power(Quality)

Start inter-frequencymeasurement

Handover is triggered Stop inter-frequencymeasurement

Time



Inter-Frequency measurements

•The handover among iso-frequency signals is executed throughmacrodiversity

•In the CDMA transmission and reception are continuous, and there is notime to make measurements

•Therefore, silence must be introduced to make measurements

•Silences are introduced through the Compressed Mode technique

•Alternatively, two receivers at frequencies can be used





Downlink compressed Transmission

Tf = 10 ms Tempo di silenzio per

misure

SF=SF0

SF=SF0/2

SF=SF0

The two “Threshold_2d” and “Threshold_2f” sign the start and the end of compressed mode



Handover FDD → GSM: Compressed Mode

10 ms radio frame

SF = 128SF = 64 SF = 64

SF = 128

SF = 128

For an intersystem Handover, the Mobile Terminal must make measurements on the GSM(GSM carrier Received Signal Strength Indicator , RSSI, e Path Loss); moreover, the mobileacquires frame synchronization and BSIC on BCCH frequencies. Terminals with onereceiver need intervals on the DL radio frame to make measurements (Compressed Mode,CM).

The CM implementation is based on SF reduction, always network initiated. TheCM is necessary even in UL for measurements on DCS 1800 MHz, in order to avoidinterferences from UMTS transmitter to DCS receiver

Gap for measurements

10 ms radio frame





Measurements and Pattern in Compressed Mode

A typical Compressed Mode pattern shows 1 gap of 7 slot every 3

frames;

Six measurements on RRSI per each gap of 4,7 ms can be done

(approximately the duration of a GSM frame)

Three samples each measure on max. 32 declared adjacent cells = 96

samples

The duration of RSSI measurements is of 480 ms per 32 adjacent cells

frame10 ms

Gap4,7 ms

The BSIC identification of the three best adjacent cells can last up to 5s

with this pattern



SF = 32 SF = 64 SF = 128

C64,2

C64,3

C32,1

C128,4

C128,5

C128,6

C128,7

SF = 256

Specifications indicate that the code assigned to the connection in

the frames in Compressed Mode is _in UL and in DL – the one with

SF/2 of the upper hierarchical level

Codes allocation in Compressed Mode

O

The voice call with AMR codec

uses, in Downlink, a code withSF 128 when CM is not used

X

Assigned to the voice call

Blocked from the call

O

X

XX

X

O





n o d e

n o d e

n o d e

b t s

b t s

b t s

B S C B S C - - B B

C N R N

S

B S S

I U c s

A I U B

A B I S

Inter-MSC HO from UMTS to GSM

M S C M S C - - B B

UE

R N C R N C - - A A

3 G 3 G M S C M S C - - A A



n o d e

n o d e

n o d e

b t s

b t s

b t s

3 G 3 G M S C M S C - - A A

R N C R N C - - A A C N

R N S

B S S

I U c s

A I U B

A B I S

Inter-MSC HO from UMTS to GSM

UE

M S C M S C - - B B

B S C B S C - - B B





UE Node-B RNC CN 3G

83

Handover execution procedures

CN 2G BSS

HO evaluation

Relocation required

GSM: HO request

GSM: HO request ACK

HO from UTRAN command

GSM: HO access + HO complete

GSM: HO complete

Relocation command



Inter RAT handover in the packet domain

Mobility procedures in the packet domain are :

Cell reselection:The mobile decides on the target cell and the reselection procedure: the network isonly informed of the cell change

Is used from the mobiles with an assigned packet service and that are sending datathrough common channels

Cell change:Is the network that, on the basis of the received measures, decides the target celland drives the cell change

Is used from the mobiles with an assigned packet service and that are sending datathrough dedicated channels





UE Node-B RNC 3G PS CN

85

Cell reselection procedure

2G PS CN

PS RAB

Routing area update request

Context request

SRNS Context Request

SRNS Context Response

Context response

Context ack

Iu Release Command

Iu Release Complete

Deletion procedure

Routing area update accept



UE Node-B RNC 3G PS CN

86

Cell change procedure2G PS CN

PS RAB

Routing area update request

Context request

SRNS Context Request

SRNS Context Response

Context response

Context ack

Iu Release Command

Iu Release Complete

Deletion procedure

Routing area update accept

UE state= Cell DCH

RRC Measurement Report

Cell change order from UTRAN





UMTS Handover

The handover can be used even for:

Load balancing: the connections are distributed on more carriers or moresystems

Service Based Handover: is the possibility to optimally serve a connection,with the GSM or UMTS network on the service basis (i.e. voice on GSM,high speed on UMTS)



UMTS radio interface




Principal parameters

UTRA/FDD UTRA/TDD

Multiple access WCDMA Ibrido WCDMA+TDMA

Chip rate

Carrier spacing 5 MHz

3.84x2 Mcps (SF FDD:4-256, TDD 1-16)

Frame duration 10 ms

N. slot per frame 15

BTS synchronizationNot necessary Not necessary

but better

modulation DL: QPSKUL: Dual-code BPSK UL: QPSK

Coherent reception Uplink and downlink

Multi-rate Variabile SF + Multi-code + Multi-slot (TDD only)

DL: QPSK



FDD and TDD

FDD

Has been standardized for public macro and micro cellular environmentwith data rates up to 384kbps and high mobility

TDD

Allows and efficient usage of the “unpaired” spectrum and supports datarates up to 2 Mbps

Is useful in environments with high traffic density and indoor coverage,where applications require high highly asymmetric data rates





TDD (TD-CDMA) component

F r e q

u e n c

y

8 TCH

per time

slot

One Time Slot

3. 8 4

M c h

i p / s

0. 2 2

r 1 2 3 . . . 14 15

Codes

1-16

Energy

Time

frame with

15 time slots

WB-TDMA/CDMA


TDD frame

3.84

Mchip/s

time

frequency

666 µs

10 ms

10 ms

10 ms





Logical, physical and transport channels



Logical Channels

Logical channels are services offered from the MAC (Medium Access Control ) tothe higher levels and are characterized from the Information Content :

Broadcast Control Common Channel (BCCH): brings the System Info and network configuration parameters

Common Control Channel (CCCH): carries bidirectional control information for themobiles that are not in Connected Mode*

Paging Common Channel (PCCH): used from the network to set up a connection withthe MT

Dedicated Control Channel (DCCH): carries control information for the MTs in “Connected Mode”

Dedicated Traffic Channel (DTCH): carries user information for the MTs in “Connected Mode” ( payload ).

*are in Idle Mode and there is no signalling connection between UTRAN and MT





Transport channels

Transport channels are the resources offered from the physical layer to higherlevel protocol; the channels can be Common (l’UE* must be explicitlyaddressed through a MAC identifier) or Dedicated .

Dedicated Channel (DCH), Downlink o Uplink; carries user plane or signaling planeinformation

Broadcast Channel (BCH), downlink transport channel which carries system or cellinformation

Forward Access Channel (FACH), DL, used to carry control or data packetinformation

Paging Channel (PCH), DL, used from the network to initiate a communication

Random Access Channel (RACH), used from the MS in UL to access the system orsending data packets

* UE= User Equipment



Logical and transport channels mapping

CCCH DCCH/DTCH

RACH DCH

PCCH BCCH

PCH BCH

CCCH DCCH/DTCH

FACH DCH

Level 2

Level 1

Uplink Downlink

Logical

channels

Transport

channels





Physical channels and indicators

Physical channels are the resources used for radio transmission: are defined bya spreading code , a carrier , a scrambling code

The correspondence between physical and transport channels is that level 2(MAC) protocols transfer elementary data units (Radio or Transport Blocks ) tothe physical layer that are elaborated (i.e. error correction coding) and sent tothe physical channels

All the physical channels (indicators, preambles, and synchronization channels )are sent in all Time Slots of the FDD frame

Indicators are signaling entities with Boolean value and are not connected totransport channels

An example of indicators are: AICH, Acquisition Indicator Channel , for the ack

to the PRACH preamble; PICH, Paging Indicator Channel, which indicates to theUE in Sleep Mode* to listen to the paging channel in a subsequent frame

* Discontinuous reception mode for energy saving



Physical and transport channels mapping

RACH

DPCH (DPDCH)PRACH

DCH PCH FACH

S-CCPCH

BCH DCH

P-CCPCH

Uplink Downlink

Physical

channels

Transport

channels

DPCH (DPDCH)





[CCCH:RACH] RRC CONNECTION REQUEST

UE UTRAN

On physical channel PRACH

[CCCH:FACH] RRC CONNECTION SETUP

On physical channel S-CCPCH

[DCCH:DCH] RRC CONNECTION SETUP COMPLETE

Example: connection establishment

On physical channel DPCH



Livello RLC

RLC SDU 1(DTCH)

RLC SDU N(DTCH)

H H

Payload – data block (i.e. TCP/IPpacket)

Header RLC adding

Segmentation and user data transmission

Application

level*

* An intermediate level can exist (PDCP, Packet Data Convergence Protocol)

to compress TCP/IP headers

Segmentation in Ninformation units

SDU= Service Data Unit

RLC= Radio Link Control





MAC PDU 1(Transport Block)

Transport

Channel (DCH)

MAC PDU N(Transport Block)

RLC Level

MAC Level

Elementary unit exchanged

between MAC and PHY

RLC SDU 1(DTCH)

RLC SDU N(DTCH)

H H

MAC SDU 1 MAC SDU NH H

Header MAC addition

RLC Blocks to send in a TTI (Transmission Time Interval)

which lasts one or more frames

PDU= Protocol Data Unit




MAC PDU 1

(Transport Block)

Transport

channel (DCH)

MAC PDU N

(Transport Block)

Elementary unit

exchanged between MAC

and PHY Transport Format*

calculation

Radio BlocksMultiplation and

Coding

TFCIelaboration

MAC

PHY

To the physical channel

DPCH (DPDCH)To the physical DPCH

(DPCCH)

* Transport Format is calculated from the number and the dimension of the

Transport Block; the whole of possible Transport Format is the Transport

Format Set.






A) In the simplest cases, like in the previous example, to a transportchannel corresponds one logical channel

B) In general, it is possible to multiply more than one logical channel on onetransport channel (MAC multiplation )

C) Finally, more transport channels can be multiplied on one physicalchannel

In this case, the whole of Transport Format is the Transport Format Combination

Follows an example of a bearer service incuded in the 3GPPspecifications




Example: 144 kbps (DL) service

Rate Matching (RM) can reach NRM bit per repetition, or remove some bits (Code Puncturing) according to a

puncturing mask

Turbo code R=1/3

R ad io fr am e FN =4 N+ 1 R adi o f ra me FN= 4N +2 R ad io fr am e F N= 4N+ 3Radio frame FN=4N

Informationdata

(TransportBlock)

CRC Attachment

2nd interleaving

4320

4232 88 4232 88 4232 88 4232

#1 4232 #2 4232 #1 88 #2 88 #3 88 # 4 88

4320 4320 4320

8464

8688

2896

CRC16 bit2880

2880

88

352

360

100

CRC12 bit

Rate matching

1st interleaving

CRC Attachment

DTCH (Payload ) DCCH (signaling)

8464

#1 4232 #2 4232

352

100

Radio Frame

Segmentation

slot segmentation

240ksps DPCH(including DPCCH bits)

Rate matching

1st interleaving

0 1 14• • • •

288 2880 1

288• • • •

14

0 1 14• • • •

288 2880 1

288• • • •

14

0 1 14• • • •

288 2880 1

288• • • •

14

0 1 14• • • •

288 2880 1

288• • • •

14

Termination 12 bit112

Tail8 bit

Convol. Coding R=1/3

TTI is 4frames long

(40 ms)

Informationdata

(TransportBlock)2880

DCH #1 DCH #2





480kbpsDPDCH

Turbo Coding R=1/3

Radio frame FN=4N+1 Radio frame FN=4N+2 Radio frame FN=4N+3Radio frame FN=4N

Informationdata

(Transport Block)

CRC attachment

2nd interleaving

4800

4702 98 4702 98 4702 98 4702

SMU#1 4702 SMU#2 4702 SMU#198

SMU#298

SMU#398

SMU#498

4800 4800 4800

4350

8688

2896Termination12 bit

2880

2880

98

360

360

112

Tail8 bit100

1st interleaving

CRC attachment

Tailbit attachment

Conv. Coding R=1/3

Rate matching

1st interleaving8700

4350

SMU#1 4702 SMU#2 4702

90 90 90 90

15kbpsDPCCH

Rate matching

Radio Frame Segmentation

100

CRC16 bit

CRC12 bit

TTI di 4trame (40ms)

Informationdata(Transport Block)

2880

DTCH (Payload )DCCH (signaling)

Example: 144 kbps (DL) service

CRC: Cyclic Redundancy Check DCH multiplation at physical level



Transport channels coding and multiplation (DL)

Radio blocks are elaborated in a TTI interval; for example the output of the AMR

voice coder is of 20 ms (TTI) duration

Frame Segmentation

Multiplexing

2nd Interleaving

Mapping to

Physical channelsAdd CRC perTr. block

Add CRC perTr. block

Channelcoding

Channelcoding

TransportChannel 1

Rate Matching Rate Matching

1st Interleaving 1st Interleaving

TransportChannel N





Il CRC (Cyclic Redundancy Check)

Logical circuitwith generatorpolinomial

Data Block(Transport

Block)

Error correction

coding (Rate 1/3)

Data block + CRC Coded

CRCData Block(Transport

Block)

Trasmission

CRC

Decoded

Data block

Reception Logical

circuit

CRC

CRCrecalculate

d

CRC decoded

Channel decoder

Block + CRC Revealed

Radio

channel

M a t c h

i n g ?

Typical lengths of CRC in UMTS are 12 or 16 bit



DL dedicated channel: frame structure

Tslot = 2560 chip , 10x2k bit (k=0..7); SF = (512/2k)

Tframe = 10 ms

Slot #iSlot #0 Slot #1 Slot #14

Tslot =0,667 ms

Tframe = 10 ms

Powercontrol

NTPC bit Ndata2 bit

DPDCH

N TFCIbit

Pilot

Npilot bitNdata1 bit

DPDCH DPCCH DPCCH

Formatindicator

(DPCH, Dedicated Physical Channel) in DL:

-DPDCH (Dedicated Physical Data Channel)

-DPCCH (Dedicated Physical Control Channel)

Every TS of the frame isassigned to the samecommunication

Data channels carry payload andcontrol messages of higher levelprotocols

DataData






Tframe = 10 ms


Tslot =0,667 ms

Tframe = 10 ms

Powercontrol

NTPC bit Ndata2 bit

DPDCH

N TFCIbit

Pilot


DPDCH DPCCH DPCCH

Formatindicator

Indicates data blockstransmission format:

channels coding,discontinuous transmissionpresence, silencedescriptor, etc.

DPDCH e il DPCCH are sentwith the same SF, variablefrom 4 and 512

DL dedicated channel: frame structure

(DPCH, Dedicated Physical Channel) in DL:-DPDCH (Dedicated Physical Data Channel)


DataData




Tframe = 10 ms


Tslot =0,667 ms

Tframe = 10 ms

Powercontrol

NTPC bit Ndata2 bit

DPDCH

N TFCIbit

Pilot


DPDCH DPCCH DPCCH

Formatindicator Data

Carries a command to

indicate to increase ordecrease the transmittedpower (es. 1 dB)

Carries a known sequenceused from the receiver forchannel estimation

DL dedicated channel: frame structure(DPCH, Dedicated Physical Channel) in DL:

-DPDCH (Dedicated Physical Data Channel)


Data





Radio interface: modulations

QPSK: 2 bit per symbol, 4 symbols in

the constellation, DPDCH and DPCCHare time multiplied

FDD DL e TDD: QPSK

Q-Branch

I-Branch

Each symbol carries DPCCH or

DPDCH

BPSK= Binary Phase Shift Keying, QPSK= Quad Phase Shift Keying

Dual BPSK: 2 symbols perconstellation, 1 bit per symbol perDPDCH e DPCCH

FDD UL: Dual BPSK

Q-Branch

I-Branch

DPDCH

DPCCH



Example: DPCH DL structure (Spec. 3GPP)

DPDCHBits/Slot

DPCCHBits/Slot

Slot Format#i

Channel BitRate (kbps)

Channel SymbolRate (ksps)

SF Bits/ Slot

NData1 NData2 NTPC NTFCI NPilot

0 15 7.5 512 10 0 4 2 0 41 15 7.5 512 10 0 2 2 2 42 30 15 256 20 2 14 2 0 23 30 15 256 20 2 12 2 2 2

4 30 15 256 20 2 12 2 0 45 30 15 256 20 2 10 2 2 46 30 15 256 20 2 8 2 0 87 30 15 256 20 2 6 2 2 8

8 60 30 128 40 6 28 2 0 4

9 60 30 128 40 6 26 2 2 410 60 30 128 40 6 24 2 0 811 60 30 128 40 6 22 2 2 8

12 120 60 64 80 12 48 4 8 813 240 120 32 160 28 112 4 8 8

14 480 240 16 320 56 232 8 8 1615 960 480 8 640 120 488 8 8 16

16 1920 960 4 1280 248 1000 8 8 16

Useful for data transmission at 384

kbit/s (coding rate 1/3: ∼950 kbit/s)Useful for voice coding

at 12,2 kbit/s (coding

rate 1/3: ∼40 kbit/s)





SF = 32 SF = 64 SF = 128

C64,0

C64,1

C32,0

C128,0

C128,1

C128,2

C128,3

SF = 256

XX

XX

X

The code CSF,0 is always blocked for common channels In each cell no more than (128-4) codes with SF 128 for voice and (8-1)

codes with SF 8 for data connections at 384 kbit/s.

OVSF code allocation

XX

X Used for common channel

signaling (BCCH, Pilot,

Paging, FACH, PICH, AICH)

X

X

Assigned to common channels

X

XX

XX

X

X

Blocked from common channels



cos(ωωωωt)

I

Q

c scrambS P cch sin(ωωωωt)DPCHDownlink

cCh : Spreading code

c scramb: Scrambling code

Downlink modulation (Single Signal)

DPDCH and DPCCH use the same OVSF code, different for each user; it is

possible the multicode transmission with DPDCH assigned to the UE (howeveronly one DPCCH per UE is transmitted)

Scrambling codes are pseudonoise sequences interrupted at 38400 chip,

extracted from a whole of (218-1) codes and grouped in 512 subset including 1

primary and 15 secondary codes; each cell uses a different subset univocally

identified from the primary scrambling code

Filter with Roll-off = 0,22





cos(ωωωωt)

I

Q

C scrambS P C spread1

sin(ωωωωt)

DPCH n°1

Downlink Modulation (all the DPCH)

I

Q

C scrambS P C spreadNDPCH n°N GN

G1

ΣΣΣΣ

ΣΣΣΣ

Gi: amplitude signal which definesthe transmitted power

adder: baseband signalscombining

Filter with Roll-off 0,22



(Tx OFF)

256 chip

CPICH (20 bits, SF=256)

P-CCPCH (18 bit, SF = 256)

Tslot = 2560 chip (0,667 ms)

Ttrama = 10 ms


Campo DatiNdata bit

NTFCI bit NPilot bit


S-CCPCHDL common channels: frame structure

P-CCPCH (Primary Common Control Physical Channel): broadcasts system infos. In the initial gapprimary and secondary SCH are sent

S-CCPCH (Secondary CCPCH ): is of variable SF. Carries the paging, signaling channels or small traffic

volumes (max 32 kbit/s). More than one S-CCPCH per cell can be configures (es. 1 S-CCPCH perpaging, 1 per dati e segnalazione)

CPICH (Common Pilot Channel): used for channel estimation and cell scrambling code research





Data fieldNdatabit


Tframe = 10 ms

DPDCH(modulator branch I)


Pilot

Npilot

bit NTPC bitNFBI bit

Format indicator

N TFCI bit

Tslot = 2560 chip, 10 bit (SF=256)

0,667 ms

Feedbackinformation

Power controlDPCCH(modulator branch Q)

DPCH UL: frame structure

Feedback field carries physical layer signaling, used for antenna diversitytechniques

DPCCH control field has fixed SF and equal to 256, while the SF of data

field DPDCH is variable (4-256).



Data fieldNdata bit


Ttrama = 10 ms

Message Part


Pilot

Npilot bit

FormatoIndicatorNTFCI bit

0,667 ms

Control Part

Tslot = 2560 chips, 10 bits (SF=256)

PRACH channel in UL: frame structure

PRACH (Physical Random Access Channel) is a common channel with contentionaccess, anticipated by preambles transmitted with increasing power*

Is used both for network access, and for signaling messages and traffic data (up to32 kbit/s).

* PRACH transmission is done only if preamble is network acknowledged





Uplink modulation

OVSF codes are the same for each UE and depend on the used SF

The network sends to the UE the eventual power offset (βC and βD factors)

DPCCH is sent even during inactivity data periods

Scrambling codes are complex pseudonoise sequences different per each UE, chosen in awhole of 224 Gold codes of length 225-2 and interrupted at 38400 chip

Spreading codes (OVSF)

cD, cC : Spreading Codes

c’ scramb: Scrambling Codes

DPDCH

cD

DPCCH

cC

Q∗∗∗∗ j

I+jQ

c’scramb

cos(ωωωωt)

Real

Imag

sin(ωωωωt)

βD

I

βC

Filter with Roll-off 0,22



Uplink Variable Rate

1-rate

Rate variabile

1/2-rate

1/4-rate

0-rate

10 ms

: DPCCH (Pilot+TPC+RI)

: DPDCH (Data)

R = 1 R = 1/2 R = 0 R = 0 R = 1/2





Example: DPCH UL (Spec. 3GPP) structure

Useful for voice codingat12,2 kbit/s (coding rate1/3: ∼40 kbit/s)

Useful for data transmissionat a 64 kbit/s (coding rate

1/3: ∼200 kbit/s)DPDCH Uplink

Slot Format #i Channel Bit Rate(kbps)


SF Bits/Frame

Bits/Slot

Ndata

0 15 15 256 150 10 10

1 30 30 128 300 20 20

2 60 60 64 600 40 40

3 120 120 32 1200 80 80

4 240 240 16 2400 160 160

5 480 480 8 4800 320 320

6 960 960 4 9600 640 640

DPCCH Uplink

SlotFormat #i

ChannelBit Rate(kbps)


SF Bits/Frame

Bits/Slot

Npilot NTPC NTFCI NFBI

0 15 15 256 150 10 6 2 2 01 15 15 256 150 10 8 2 0 02 15 15 256 150 10 5 2 2 13 15 15 256 150 10 7 2 0 1

4 15 15 256 150 10 6 2 0 2

5 15 15 256 150 10 5 1 2 2



Example: 144 kbit/s data service

144+15=159 kbit/s

477 kbit/s

480 kbit/s

3,84 Mchip/s

User bit rate + associated signaling

Signal in input at RF modulator

Rate Matching (Bit Repetition)

Multiplication for OVSF

Code of length (Spreading Factor) = 8

Error correction coding,

Rate = 1/3





Variable Bit Rate on DPCH

The transmission at variable bit rate in Uplink uses variable SF for the DPDCH; thecontrol field (and therefore the TFCI) is sent at fixed SF

In Downlink the SF of data and control fields is the same; the variable bit ratetransmission is obtained using DTX

It is possible to change transmission speed with channel reconfigurationprocedures

R = 1

R = 1/4

R = 0

Downlink DPCCH (Pilot+TPC+TFCI) Downlink DPDCH (Data)

0.667 ms

variableBit Rate (R)

Uplink DPCCH (Pilot+TPC+TFCI)

R = 1 R = 1/2 R = 0 R = 0 R = 1/2

Uplink DPDCH (Data)

10 ms



An introduction to UMTS radio protocols





UMTS network architecture

Packet domain

RNCRNC

RNC areacell

RNCRNC

Iub

Circuit domain

RNCRNC

MSCMSC

VLR

MSCMSC

HLRHLRPLMN, ISDN, PSTN...

GatewayMSC

GatewayMSC

HLR

Iu (CS)

Iu (CS)

Node B

UE

SGSNSGSNGGSNGGSN

Public packet

network

Iu (PS)Gn

Gi

Uu

Iur

Iu (CS)

Iur



Control and user plane

MAC

RRC

Control Plane User Plane

RLCRLC

RLC

PDCPPDCP

PDCP

Signaling

messages

handling and

transportation

over control

channels

Control and traffic channels are logical channels, defined on the basis of carried

information

Logical channels

Physical layer (Transmission) L1 (PHY)

L2/RLC

L2/MAC

L3

payload handling

and transportation

over control

channels

Transport channels





Functionalities of UMTS radio protocols

MAC

RRC

Control Plane User Plane

RLCRLC

RLC

PDCPPDCP

PDCP

Canali logici

Physical layer (Transmission) L1 (PHY)

L2/RLC

L2/MAC

L3

Canali di trasporto

Radio Resource ControlRadio resources

assignment and release,

admission and congestion

control, handover

Radio Link Control

Flow control,

segmentation, error

and sequence control,retransmissions

Medium Access Control

Packet queuing , users

priority handling Physical Layer: Power Control, modulation, channel

coding, synchronization, multiplexing, measurements

Packet Data ConvergenceProtocol: IP header

compression for radio

transmission



UMTS Protocols termination

UTRAN

Iu

Iur

Iub

VLR HLR

GSN+

MSC+

UMTS Core Network

PCM

Packet Switched

Circuit Switched

Uu

Node B

Node B RNC

Node B

Node B

RNC

RRC RRC

MAC MAC

RLC RLC

PHY

PHY

IP/GTP

ATM/AAL2

CMM

CC

CCMM CMM

SM

SMPMM

Level 2 e 3 ( AccessStratum) protocols are

terminated ar the RNC

The radio physical levelis node B terminated

Session protocols are (Non- Access Stratum) terminated inCore Network





Utran: access procedures

UE

RRC connection request

UE capabilities

CNRAB assignment

QoS RAB parameters

RAB parameters

UE capabilities

RRM strategies

Iu parameters

RB parameters

UTRAN



RRC Protocol States Idle mode:

No dedicated radio resource isallocated

the UE has to perform neighborcell monitoring, cell reselection,paging channel observation,broadcast message receptionand decoding

Connected mode: A duplex radio connection exists

A differentiation has to be madewith respect to dedicated andshared connections

Idle

Mode

Connected

mode

Established dedicated connection

Release connection

Established

shared connection

Release logical connection





An introduction to Radio Access Bearer (RAB)



Is the transport service offered from UTRAN to the ent-to-end

architecure of UMTS system

TE MT UTRAN CNIuEDGENODE

CNGateway

TE

End-to-End Service

TE/MT LocalBearer Service

UMTS Bearer Service External BearerService

UMTS Bearer Service

Radio Access Bearer Service CN BearerService

Backbone

Bearer Service

Iu Bearer

Service

Radio Bearer

Service

UTRAFDD/TDD

Service

PhysicalBearer Service

For each RAB aredefined: traffic class(i.e. conversational or

interactive), maximumbit rate , tolerated

delay, CS or PS domain,supported service or

application (i.e. voice)

RAB is mapped on a Radio Bearer

by configuring parameters of

radio (PHY) and layer 2 protocols

(MAC and RLC)

Radio Access Bearer (RAB)





Radio Access Bearer (RAB)

* High Speed DL Shared Channel, used only with HSDPA (High Speed Downlink Packet Access) introduced with UMTS Release 5

RAB is the bearer service offered from UTRAN; RAB are distinguished from peak bit rate,allowed delay, residual error rate, and are grouped into four service classes

PacketHS-DCHModerately sensitive todelay

10-41200-14400Interactive orbackground

PacketDCHSensitivity to jitter10-464Streaming

CircuitDCHSensitivity to jitter10-457,6Streaming

CircuitDCHSensitivity to delay and jitter

10-664;128;384Conversational(ISDN,videocall)

PacketDCHModerately sensitive todelay

10-464-384Interactive orbackground

CircuitDCHSensitivity to delay and jitter

10-34,75-12,2Conversational (voicewith adaptivecoding)

domainTransportchannel

Delay sensitivityResidualBER

Peak bit rate(kb/s)

Service class



RAB and Signaling Radio BearerFor some services more RAB subflows are identified, for example the ones

that carry least significant bits of the voice coder. Different subflows can be

treated differently from level 2 protocols (i.e. channel coding and CRC can

be different)

Signaling Radio Bearer (SRB) are bearers of the control plane; they

autonomously subsist if no payload is exchanged (i.e. paging or call setup)

or they are associated to a (look at the table) Radio Bearer and with it

multiplied. SRB bring signaling of the radio RRC protocol or of the Non

Access Stratum (CM, MM) protocols.

Service Class Peak Bit Rate (kbit/s) SRB Bit Rate (kbit/s) domain

Conversational(voice AMR)

12,2 UL/DL 3,4 UL/DL Circuit

Conversational(ISDN, Videoconference)

64 UL/DL 3,4 UL/DL Circuit

Interactive or Background 64 UL/ 384 DL 3,4 UL/DL Packet





TTI: Transmission Time Interval

TTI is the minimum interval for transmission resourcesassignment, and can be one or more frames

Typically TTI is equal to 20ms for the voice call like in the GSM system

In the case of data transmission, TTI can be extended up to 40ms



Layer RAB/Signalling RB RAB subflow #1 RAB subflow #2 RAB subflow #3

Logical channel type DTCH

RLC mode TM TM TMPayload sizes, bit 39, 81 103 60

RLC

Max data rate, bps 12200

MAC header, bit 0MAC

MAC multiplexing N/A

TrCH type DCH DCH DCHTB sizes, bit 39, 81 103 60

TF0, bits 0 0 0TF1, bits 39 103 60

TFS

TF2, bits 81 - -TTI, ms 20 20 20

Coding type CC 1/3 CC 1/3 CC 1/2

Layer 1

CRC, bit 12 N/A N/A

The DTCH is mapped on three DCH (DTCH:DCH ) corresponding to three

subflows

Transport channel Logical channelTransport

Block

dimension

Information unit

Payload

Transmission Interval

Example: voice RAB at 12,2 kbit/s+SRB at 3,4 kbit/s





For each DCH three transmission format exist: per DTX (inactive source), perSID (Silence Descriptor of background noise), per voice frame


Layer RAB/Signalling RB RAB subflow #1 RAB subflow #2 RAB subflow #3


RLC mode TM TM TMPayload sizes, bit 39, 81 103 60

RLC




TrCH type DCH DCH DCHTB sizes, bit 39, 81 103 60

TF0, bits 0 0 0TF1, bits 39 103 60

TFS

TF2, bits 81 - -TTI, ms 20 20 20

Coding type CC 1/3 CC 1/3 CC 1/2

Layer 1

CRC, bit 12 N/A N/A

Posible Transport FormatTransport Format (TFS)



RAB/signalling RB SRB#1 SRB#2 SRB#3 SRB#4Layer

User of Radio Bearer RRC RRC NASHigh prio

NASLow prio

Logical channel type DCCH DCCH DCCH DCCH

RLC mode UM AM AM AMPayload sizes, bit 136 128 128 128

Max data rate, bps 3400 3200 3200 3200

RLC

AMD/UMD PDU header, bit 8 16 16 16

MAC header, bit 4 4 4 4MAC

MAC multiplexing 4 logical channel multiplexing

TrCH type DCH

TB sizes, bit 0, 148 (alt 0, 148)TF0, bits 0TFS

TF1, bits 148TTI, ms 40Coding type CC 1/3

Layer 1

CRC, bit 16

Transport channel Logical channelSignaling type

Possible Transport Format

Example: voice RAB at 12,2 kbit/s+SRB at 3,4 kbit/sControl plane SRB; DCCH are 4, and are MAC multiplexed on a DCH (DCCH:DCH )

NAS = Non Access Stratum (protocols terminated out of the UTRAN, i.e. in CN)





TFCS size 6TFCS (RAB subflow#1, RAB subflow#2, RAB subflow#3,DCCH)=

(TF0, TF0, TF0, TF0), (TF1, TF0, TF0, TF0), (TF2, TF1, TF1, TF0),(TF0, TF0, TF0, TF1), (TF1, TF0, TF0, TF1), (TF2, TF1, TF1, TF1)

All possible Transport Format combinations

for voice and signaling

The whole of 6 combinations (TFC, Transport Format Combination) is the

TFCS (Transport Format Combination Set)

the TFC is coded each TTI in the Transport Format Combination Indicator (TFCI), send on the DPCCH

At different Transport Format correspond different instantaneous bit rate

because the Transport Blocks have different dimensions


Six possible Transport Format combinations for the RAB: DTX, SID and

voice frame, with or without associated SRB (DCCH)

DTX SID Voice



RAB differences: Examples (1)Characteristics of a Conversational RAB CS, 64 kbit/s

Layer RAB/Signalling RB RAB


RLC mode TMPayload sizes, bit 640


RLC

TrD PDU header, bit 0



TrCH type DCH

TB sizes, bit 640TF0, bits 0x640TFS

TF1, bits 2x640

TTI, ms 20

Coding type TC

CRC, bit 16

Layer 1

Max number of bits/TTI after channel coding 3948

Requirements of a Conversational RAB :

Limited delay and jitter

CBR source or of “On-Off” type

No acknowledged transmission







RLC mode TMPayload sizes, bit 640


RLC




TrCH type DCH

TB sizes, bit 640TF0, bits 0x640TFS

TF1, bits 2x640

TTI, ms 20

Coding type TCCRC, bit 16

Layer 1


RLC in Transparent Mode: RLCdata units are notacknowledged

TTI of 20 ms

Transport Formats correspond toistantaneous bit rates 0 and 64

kbit/s

RAB differences: Examples (2)

Characteristics of a Conversational RAB CS, 64 kbit/s



RAB Streaming CS, 57,6 kbit/s

RAB Streaming requirements:

Limited Jitter

No acknowledgment/retransmission of received data units

VBR souces



RLC mode TM

Payload sizes, bit 576


RLC


MAC header, bit 0MACMAC multiplexing N/A

TrCH type DCH

TB sizes, bit 576

TF0, bits 0x576TF1, bits 1x576TF2, bits 2x576TF3, bits 3x576

TFS

TF4, bits 4x576TTI, ms 40


Layer 1







RAB Streaming CS, 57,6 kbit/sLayer RAB/Signalling RB RAB


RLC mode TM

Payload sizes, bit 576


RLC


MAC header, bit 0MACMAC multiplexing N/A

TrCH type DCH

TB sizes, bit 576

TF0, bits 0x576TF1, bits 1x576TF2, bits 2x576

TF3, bits 3x576

TFS

TF4, bits 4x576TTI, ms 40

Coding type TC

CRC, bit 16

Layer 1


Transparent RLC : RLC dataunits are not acknowledged

TTI of 40 ms

Transport Formats correspond toinstantaneous bit rate 0; 14,4;28,8; 43,2 e 57,6 kbit/s




Interactive/Background PS RAB, 64 kbit/s


Logical channel type DTCHRLC mode AM

Payload sizes, bit 320Max data rate, bps 64000

RLC

AMD PDU header, bit 16



TrCH type DCH

TB sizes, bit 336TF0, bits 0x336

TF1, bits 1x336

TF2, bits 2x336TF3, bits 3x336

TFS

TF4, bits 4x336

TTI, ms 20


Layer 1


RLC operates in Acknowledged ModeTransport Formats correspond toinstantaneous bit rates 0, 16, 32, 48 and64 kbit/s






Physical Level Procedures



Open Loop Power Control on PRACHThe mobile sends the PRACH with the minimum power necessary ho

have at the receiver side an adequate C/I

Node B

RNC

Configurationparameters: power ofl

CPICH, P-CCPCH and S-

CCPCH, offset tocommunicate to the

mobiles

Iub

UE is informed on the BCCH

System Info del BCCH of CPICH power, on the

interference at Node B side

and on the offset* to apply

UE measures the power received onCPICH and calculates path

attenuation; the power on PRACH

preamble [dB] is: P_Tx_UE=Path_Att+Inteference+offset_PRACH

C/I at Node B [dB] = P_Tx_UE − Path_Att − Interference

* offset [dB] can have

a positive or

negative value

depending on therequired C/I





Instantaneously controls the UE transmission power to maintain the required

C/I (SIR in 3GPP terminology).

Node B

RNC

Configuration parameters: step

∆TPC of Power Control (es. 1 dB),C/I target for the DCH

Iub

L’UE, according to the

command received in the

previous Time Slot, increases

or decreases the transmission

power of ±∆TPC

Measures thel C/I on the DPCCH UL

(campo pilota): if C/I_DPCCH<C/I_Target,

is sent the “UP” (1) command on DPCCH

DL. If C/I_DPCCH>C/I_Target, the sentcommand is “DOWN”(-1)

Closed Loop Power Control on DPCH: Uplink



Instantaneously controls the node B transmission power to limit the

interference and maintaining the connection quality requirements in term of

Block Error Rate

Node B

RNC

Configuration parameters:

step ∆TPC of Power Control(i.e. 1 dB), BLER target forRAB, initial power on DPCH DL

Iub

L’UE is informedthrough the

Information Element

“Quality Target” of the

BLER Target

Closed Loop Power Control on DPCH: Downlink

The UE, through an internal table

terminal dependent, maps a

C/I_Target to the BLER_Target

network indicated

* The algorithm allows the UE to operate at lower C/I





Node B

RNC

Iub

The node B, according with

the command received theprevious time slot,

increases or decreases the

±∆TPC

L’UE measures the C/I on DPCCH DL (pilot

field): if C/I_DPCCH<C/I_Target, sends to

Node B the “UP” (1) command on the

DPCCH UL. If C/I_DPCCH>C/I_Target, the

generated command is “DOWN”(-1)

3GPP specifications handle faulty terminals by limiting the transmitted power

to one UE and by containing the consecutive (+ DTPC) increments

Closed Loop Power Control on DPCH: Downlink



Tslot =0.667 ms

Powercontrol

NTPC bit Ndata2 bit

DPDCH

N TFCIbit

Pilot

Npilot bit

Datafield 1

Ndata1 bit

DPDCH DPCCH DPCCH

Formatindicator

Datafield 2

DPCCH Downlink

Indicates to increase or decrease the transmittedpower

Known sequence used forchannel estimation

Closed Loop Power Control on DPCH

Pilot

N pilot bit NTPC bitNFBI bit

Format indicator

N TFCI bit

Feedbackinformation

Powercontrol

DPCCH UplinkTslot =0.667 ms

Indicates to increase or decrease thetransmitted power

Known sequence used for

channel estimation





Outer Loop Power Control on DPCH

Nodo B

RNC

RNC calculates the BLER from CRC* on DCH UL

radio blocks. If the BLER is lower than RABrequirements, indicates to Node B to decrease the

C/I_Target (i.e. of 0,2 dB); in the opposite case,

indicates to increase thel C/I_Target

Iub

L’UE calculates the BLER of

DCH DL through the CRC* and,

following the corresponding

table BLER and C/I, changes the

C/I_Target of the Closed Loop

Downlink procedure

Uses the C/I_Target recalculatedon the basis of RNC in the Closed

Loop Uplink procedure

Updates the C/I_Target (Node B side) and BLER_Target (UE side) used in the

Closed Loop procedure. Outer Loop algorithms, that operate on a scale of centsof ms, are manufacturer dependent



-20 -19 -18 -17 -16 -150,000

0,025

0,050

0,075

0,100

0,125

Fitting: Gauss

µgauss

= -18.2 dB

σgauss

= 0.41 dB

PDF of C/I ratio at Node B - System Load: 74.4 kbps/MHz/cell

[email protected] kbps, Perfect Power Control

P r o b a b i l i t y D e n s i t y F u n c t i o n

Carrier to Interference Ratio at receiver side (dB)

Power Control Uplink: C/I PDF at the Node B

C/I PDF function is very narrow because the power control algorithm

points to the C/I_Target.

F o n t : C o R i T e l ( P a c e A . – M a z z e n g a F .

)





Power Control Uplink: PDF of UE transmitted power

Dynamic of transmitted power is wide: path attenuation varies in function of

distance and fading

F o n t : C o R i T e l ( P a c e A . – M a z z e n g a F .

)

-70 -60 -50 -40 -30 -20 -10

0,00

0,01

0,02

PDF of UE Tx Power - [email protected] kbps, System Load: 61.6 kbps/MHz/cell

Perfect Power Control - Max. UE Tx power: 24 dBm (-6 dB)

P r o b a b i l i t y D e n s i t y F u n c t i o n

UE Transmit Power (dB)



Primary

SCHSecondarySCH

2560 chips

cp cp cp

Slot #0 Slot #1 Slot #14

(Tx OFF)

256 chip

P-CCPCH (18 bit, SF = 256)

Time Slot (2560 chip, 0,667 ms)

frame (10 ms)


Trama (10 ms)

cs(i,0) cs(i,1) cs(i,j) cs(i,14)

Synchronization channels structure





Synchronization channels characteristics Primary SCH: is a modulated sequence 256 chip long, unique for each

cell, used to acquire slot synchronization

A matched filter with sliding window is used

Matchedfilter

Identifies thecorrelation

peck and

distributes the

timing

Baseband (Rc

chip/s) P-SCH sequence

Secondary SCH: is a sequence of 15 words (1 per Time Slot) of 256 chip,

taken from a family of 16 known words

16 correlators are used and a sequence of 15 words identifies:

1. The group of 8 primary scrambling codes (64 possible), to which theprimary code of the cell belongs

2. The Time Slot (index from 0 to 14), to acquire frame and Time Slot

synchronism



Frame and slot synchronism acquisition1. The UE searches the primary synchronization code of 256 chips, sent on the

primary SCH, through a matched filter; a peak at the output indicates slot

synchronization

2. The secondary code Csi,j indicates both the group of 8 primary scrambling codes

(index i, with value from 0 and 0 e 63) to which the primary cell code belongs,

both the Time Slot (index j from 0 and 14). The secondary codewords are only 16

and their particular sequence (known from the correlation) indicates group and

slot

3. A third correlation process with the CPICH allows the primary scrambling code

identification among the 8 indicated Csi,j and to decode the P-CCPCH

Primary

SCHSecondarySCH

2560 chips

cp cp cp


frame (10 ms)

cs(i,0) cs(i,1) cs(i,j) cs(i,14)





Network Access Procedure

Contention access, with collisions In Uplink the PRACH channel is used, with preambles at increasing

power and a final part, the message

Only PRACH message brings signaling or data

The message is transmitted only if the preamble is acknowledged from

the downlink channel AICH ( Acquisition Indicator Channel)

For preambles and AICH, the time is divided into Access Slot:

The Access Slot are grouped into 12 non overlapping ensembles, out of phased of an integer number of frames (SFN, System Frame Number )

The mobile randomly selects one of the available ensembles, and an

Access Slot in it

The preamble is a sequence of 4096 chip, that the mobile randomly

selects in 16 possible sequences (signature).



Access Procedure - Evolution

t

Reception at UE side

t

Transmission at UE side

1° Pre-amble

Access Slot AICH(2 Time Slot, 5120 chip)

Access Slot RACH(2 Time Slot, 5120 chip)

4096 chip

2° Pre-

amble

AICH

Message

PRACH

10 o 20 ms

TP-P (3 o 4 Access Slot) TP-M (3 o 4 Access Slot)

TP-A (3 o 4 Time Slot)

4096 chip





UMTS security



Network Access Security - Network Domain Security

RNC

RNCNode B

Node B

Node B

Node B

UTRAN

Iu

Iur

Iub3GMSC

VLR

HLR

SGSN GGSN

Iu CS

Iu PS Gn

Gs

3GGMSC

Gr Gc

Network Access Security Network Domain Security





2G Security brainstorming

Main 2G Security features

• User identity confidentiality (IMSI TMSI)

• 2G AKA procedure

• Ciphering

Due to the closed nature of SS7 networks, 2G does not expect

Network Domain Security features.



2G Security brainstorming2G AKA procedure AuC/HLR

(triplets generation)

RANDKiKi

A3 A8

RAND SRES Kc

Kc (to the BTS, CS only)

Visited VLR/SGSN

RAND SRES Kc

=??

Y

S u c c e s

s ! !Kc (to the MS)

SRESuser

RANDKiKi

A3A8

Kc

SIM card





2G Security brainstorming -Ciphering

“Ciphered text”

Frame

number

(22bits)

Kc

(64bits)

A5/GEA

“Clear text”

Frame

number

(22bits)

Kc

(64bits)

A5/GEA

“Clear text”

MS BTS (CS) / SGSN (PS)



3G Security (Rel-99)Main 3G Security features

• User identity confidentiality (IMSI TMSI)

• Confidentiality

• Data integrity

• 3G AKA procedure





3G Security (Rel-99) -

User identity confidentiality

• IMSI confidentiality

• User Location confidentiality

• User untraceability

TMSI/P-TMSI allocation/re-allocation + Ciphering



N E W ! !

N E W ! !

3G Security (Rel-99) -3G AKA procedure

• User authentication

• Network authentication

3G AKA procedure provides:

• Cipher key generation

• Integrity key generation






CK, IK (to the serving RNC)

Visited VLR/SGSN

S u c c e s s !

!

=??

Y

RAND XRES CK IK AUTN

X R E S

AuC/HLR

RAND, K,

SQN, AMF

A V s

g e n e r a t i o

n

RAND X RES CK IK AUTN

CK, IK (to the UE)

USIM

K

N e t w o r k

A u t h e n t i c

a t i o n

C K, I K, X R

E S u s e r

c a l c u l a t i o

n XRESuser

RAND, AUTN




• As for 2G, the 3G AKA procedure is a “Challenge-Response”

mechanism.

• As for 2G, the corner stone of the whole security is a

Subscriber-specific 128bits-long secret key, named “K”. It is

securely stored on the USIM card and in the HPLMN (in the

AuC). Nobody can access the “K” key and it is never

transmitted, neither within the HPLMN.

• As for 2G, 3G AKA procedure is based on pre-calculated

Subscriber-specific authentication vectors (AVs).

• The main differences between 2G and 3G AKA procedures are

the “IK generation” and the “Network Authentication”

features.






3G AKA procedure AuC/HLR

AK

f1 f2 f3 f4 f5

R A N D

KSQN

AMF

IKMAC

AUTN

CKX R E S


3G AVs generation.

INPUTs:

• K = Subscriber-specific secret key

(128 bits), stored in the AuC.

• RAND = random-like data (128 bits)

generated by the AuC.

• SQN = sequence number, generated

by the AuC.

• AMF = Authentication and key

Management Field.




AuC/HLR

AK

f1 f2 f3 f4 f5

R A N D

KSQN

AMF

IKMAC

AUTN

CKX R E S


3G AVs generation.

OUTPUT: Subscriber-specific

Authentication Vectors (AVs or simply

“Quintets”).

• RAND = cfr. INPUTs

• XRES = Expected signed Response

(32-128 bits).

• CK = Ciphering Key (128 bits).

• IK = Integrity Key (128 bits).

• AUTN = Authentication Token (it

allows the Network Authentication).






AuC/HLR

AK

f1 f2 f3 f4 f5

R A N D

KSQN

AMF

IKMAC

AUTN

CKX R E S


3G AVs generation.

• f1 = 4-inputs message authentication

function.

• f2 = 2-inputs message authentication

function. It is the “equivalent” of

the 2G “A3” algorithm).

• f3, f4, f5 = 2-inputs key generation

functions. f3 is the “equivalent” of

the 2G “A8” algorithm.

Note: f1, …, f5 are Operator-specificone-way functions, securely stored

on the USIM and in the AuC.



USIM

AK

f4 f3 f2

f5SQN

K MACAMFSQN xor AK AUTN, RAND

from VLR/SGSN

f1

RAND

XMAC =??

MA C

IK (to the UE)

Y S U C C E S

S F U L

N e t w o

r k

A u t h

e n t i c a

t i o n

CK (to the UE)

AUTN

RES (to VLR/SGSN)







Confidentiality

• Cipher algorithm agreement

• Cipher key agreement

• Confidentiality of user/signalling data

The following features are provided:

Security mode negotiation mechanism + 3G AKA procedure

+ Ciphering over radio access interface.



3G Security (Rel-99) -Confidentiality

• 3G ciphering is based on the same principle of the 2G

one (stream cipher concept).

• It occurs between UE and RNC, where “f8” is located.

• 2G “A5” 3G “f8”.

Main aspects:

• As “A5”, in order to allow roaming, “f8” is “standard”.

• Kc (64bits) CK (128bits).






Data integrity

• Integrity algorithm agreement

• Integrity key agreement

• Data integrity and origin authentication of signalling data

The following features are provided:

Security mode negotiation mechanism + 3G AKA procedure

+ Integrity over radio access interface.



3G Security (Rel-99) -Data integrity

• Data integrity provides individual control message.

• It occurs between UE and RNC, where “f9” is located.

Main aspects:

• Similarly to “f8” , in order to allow roaming, “f9” has to

be “standard”.

• It is based on the “traditional” MAC concept, by using the

128bits-long IK, generated by the 3G AKA procedure.





2G-3G Security interoperability

R e l e as e 9 9 + V L R / S G S N Release 98-

V L R / S G S N

R e l e a s e 9 9 +

H L R / A u C

U S I M

R A N D

A U T N

R E S

C KIK

C K , I KK c

U T R A N

R 9 9 + M E c a p a b le o f

U M T S A K A

R A N D

A U T N

R E S

[ K c ]

C K , I KK c

G S M B S S

C K , I K K c

R E S S R E S

C K , I K K c

R 9 9 + M E n o tc a p a b l e o f U M T S

A K A

o r R 9 8 - M E

C K , I K K c

C K , I K K c

R E S S R E S

R A N D

[ A U T N ]

S R E S

[ K c ]

K c

R A N DS R E S

[ K c ]

K c

M E

C K , I K K c

R E S S R E S

Q u in tet s T riple t s

C K , I K K c

R E S S R E S

U M T S secu r ity c on te x t G SM secu r ity con tex t

C K , I K K c



The UMTS evolution: HSDPA





What is HSDPA?

HSDPA is a whole of radio functionalities for

Optimization of asymmetric packet transmission

(Streaming, interactive, FTP/e-mail)

Intermittent transmissions handling with high peak bit

rate

Increase of UMTS spectral efficiency

Lower latency



HSDPA positioning

100 m 1000 m 10 km

100 kbit/s

1 Mbit/s

10 Mbit/s

U MT S R e le as e 9 9

H S D P A ( U M T S R e l e a s e 5 )

WLAN (802.11b)

EDGE

GPRS

Transmission

speed

Cell radius





HSDPA innovations

Intoduction of a transmission channel shared among different

users for the downlink

Scheduling of the transmission queues demanded to the base

station: the MAC level has been decentralized

Multiplation on the time domain using subframes (TTI) of 2ms

Hybrid ARQ techniques for corrupted radio blocks handled from

the node B

Adaptive modulation and coding

Use of QAM modulation to increase spectral efficiency

Peak speed up to 14 Mb/s



16-QAM modulationAverage power equal to

peak power

Non constant

envelop

QPSK: 4 symbols, 2 bit per symbol 16 QAM: 16 symbols, 4 bit per symbol





Intermittent service handling in R99

Data on DCH Tinact (1 -3 s)

Signaling onFACH

Source inactivity (empty transmission buffers)

Source activity

Tact (1 -3 s)

Synchronization

Data on DCH

t

DPCCH (control channel)

DCH release

DPCCH

Transition on common channels

Transition on dedicated channels

The DL code is busy even in inactive intervals (at least DPCCH is

sent)

Code allocation and code deallocation handled by timers: the

units are one or more frames Synchronization need

Scarce efficiency for intermittent services



HSDPA:

Code and Time multiplexing

The idea of the HSDPA is to allocate resources for lower time

intervals

A new transport channel named HS-DSCH (High Speed Downlink

Shared Channel) is used On the HS-DSCH the TTI is reduced to 2 ms (3 Time Slot), even

if the frame organization is the same

Different users can be multiplexed on adjacent TTI of the same

frame

HS-DSCH

user 1HS-DSCH

user 2HS-DSCH 1

Utente1

time

c o d e s

time

DCH – user 3

DCH - user 4

HS-DSCH 1

Utente 2

HS-DSCH 2

Utente1HS-DSCH 2

Utente 3

DCH - user 5

C o d i c iDedicated channels:

Users multiplexed only oncode basis

Shared channels: users

Multiplexd on code

and time basis





HS-DSCH assignment and release

For Power Control and signalling, each user uses a DL associated dedicated

channel at low bit rate (i.e. 3,4 kbit/s and SF 256)

The scheduling information is carried on a shared control channel, the HS-SCCH

(High Speed Shared Control Channel).

DCH at low bit rate, mobile 1

time

DCH at low bit rate, mobile 2

data on HS-DSCH

(mobile 1)signallingonHS-SCCH

signallingonHS-SCCH

Data on HS-DSCH

(mobile 2)

signallingonHS-SCCH

signallingonHS-SCCH

Dati on HS-DSCH

(mobile 1)

Data onHS-DSCH

(mobile 1)

1 TTI 1 TTI

1 frame



Physical channel HS-PDSCH

Spreading factor equal to 16

Up to 15 codes to the same user in the same TTI

In each TTI only one Transport Block is sent

subframe HS-DSCH (2 ms)


HS Physical DSCH , Tslot = 0,667 ms

Ndata bit (2560chip , 320/640*bit, SF = 16)

* 320 bit if QPSK, 640 if 16QAM





DCH and HS-DSCH differences

Prestazione DCH Downlink HS-DSCH

Variable Spreading Factor yes (4÷ 256) No (16)

Closed loop power control yes No

modulation QPSK QPSK e 16-QAM

Modulation and adaptive coding No yes

H-ARQ - No yes

Multicode modality No yes ÷

TTI duration minimum 10 ms 2 ms

Soft Handover yes No

Maximum Bit Rate 384 kbit/s 1÷14 Mbit/s

RNC Nodo BScheduler



New channels in HSDPA

Scheduling information is carried in a shared control channel, the

HS-SCCH

It is possible to transmit up to 4 users in the same TTI on groups

of codes with SF 16

One HS-SCCH can address one user

In Uplink, the radio block Ack/Nack is carried on a physical

control channel, the HS-DPCCH

Even for the HS-DPCCH a structure with three time slots is used:

the first for Ack/Nack, in the other two the CQI

In Uplink, traffic and signaling are carried on a dedicated

associated channel corresponding to R99 (i.e. 64 kbit/s payload +

3,4 kbit/s for signaling).





Transmission

∼19200 chip (5ms)

HS-DSCH

Reception at UE

time

Transmission at UE HS-DPCCH

Reception at Node B

Block 1

Block 2

Block 3

Block 4

Block 5 Block 6 Block 1

Block 7

TTI (3 TimeSlot, 2 ms)

Elaboration

∆TNACK ACK ACK ACKACKCQI CQI CQI CQI CQI



Temporal relationship among DL channels

PCCPCHReception at the UE

1 frame = 15 Time Slot = 10 ms

HS-SCCH

1 TTI = 3 Time Slot = 2 ms

HS-DSCH

1 TTI = 3 Time Slot = 2 ms

2 Time Slot = 1,33 ms

Part 1: MS,CCS, UE ID

Part 2: TBS,HARQ, UE ID

Each HS-SCCH (up to 4) uses a code with SF 128 and is organized in subframes of

2 ms (3 Time Slot) In part1 (1 TS) the information necessary to demodulate the HS-DSCH is sent:

modulation (MS), MAC UE identifier, number and position of used OVSF (CCS,

Channelization Code Set)

Part 2, overlapping to the HS-DSCH, allows the decoding: HARQ informations and

block dimentions (TBS)





HSDPA Channels

HS-DPCCH is sent on the UL Dual-BPSKmodulator, together with the

dedicated associated DPCCH

The table has been taken on RAB HSDPA proposed in 3GPP.

Downlink SF codes Net Bit Rate [kbit/s]

HS-DSCH 16 1 ÷ 15 900 ÷ 14400 ( payload )

DCH - 256 1 3,4 (signaling)

HS-SCCH 128 1 ÷ 4 - (control channels forscheduling)

Uplink SF codes Net Bit Rate [kbit/s]

DCH - 8 ÷16 1 64 ÷ 128 ( payload ) + 3,4(signaling)

HS-DPCCH 256 1 - (Ack/Nack and CQI)

(associated to HS-DSCH)

(associated to HS-DSCH)



Hybrid ARQ and Incremental RedundancyRadio block

Coded block (Rate 1/3)

1st transmission (Self Decodable)

ritransmission(Non-self Decodable)

Coder Rate 1/3

puncturing

Node B

Mobile Terminal

Failed decoding

NACK

Combination anddecoding OK

ACK

X

X





Fast Scheduling and CQI

Nodo B

Mobile 1

Mobile 2

C Q I : g o

o d c h

a n n e l q

u a l i t y C

Q I : s c a r c e c h a n n e l q u a l i t y

Decision on scheduling e AMC*

CQI is a metric calculated each 2 ms basing on the pilot channel, and indicates

the transmission format (power, modulation, coding scheme) that the mobilecan receive in the subsequent TTI with Block Error Rate (BLER) lower than 10%

* Adaptive Modulation & Coding



Example: CQI and transmission formats CQI is a 5 bit information word (32 values)

The correspondence among CQI values and transmission formats is

different for each class of MTs; follows the case of class 10 UE

CQI

(0 ÷ ÷÷ ÷ 31)

modulation Transport Block [bit]

Coding Rate Number of codes

4 QPSK 317 1/3 1

6 QPSK 461 1/2 1

9 QPSK 931 1/2 2

11 QPSK 1483 1/2 4

13 QPSK 2279 1/2 5

15 QPSK 3319 ∼0,7 5

16 16-QAM 3565 ∼0,4 5

18 16-QAM 4664 1/2 5

25 16-QAM 14411 3/4 10

30 16-QAM 25558 ∼0,9 15

i.





Orthogonal codes : coexistence with R99

In each cell where HSDPA is active, it is necessary to keep:

From 1 to 15 codes with SF 16 for HS-PDSCH channels

From 1 to 4 codes with SF 128 for HS-SCCH

Many codes with SF 256 associated to the dedicated channels per each

HSDPA session

A portion of the transmission power for HS-PDSCH e HS-SCCH

The coexistence HSDPA and R99 services on the same carrier must

provide dinamic mechanisms for resource allocation to HSDPA

A basic configuration to verify the coexistence is:

5 codes with SF 16 for HS-PDSCH, and 1 for HS-SCCH

20-30% of the allocated power to HSDPA.



OVSF codes assignment (CCS field of the HS-SCCH)

SF = 32 SF = 64 SF = 128

C64,0

C64,1

C32,0

C128,0

C128,1

C 128,2

C128,3

SF = 256

C16,0

C16,1

C32,1

C16,14

C16,15

SF = 16 SF = 32 SF = 64 SF = 128

C64,0

C64,1

C32,0

C128,0

C128,1

C 128,2

C128,3

SF = 256

C16,0

C16,1

C32,1

C16,14

C16,15

SF = 16

Group of codesposition forHS-DSCH -(Starting Node )

15 codes

Blocked code for

Signallingchannels





Transmission formats

Transmission formats are defined on the basis of:1) The number of codes assigned in the TTI for the HS-PDSCH

2) the modulation, QPSK or 16-QAM

3) The radio block dimension, which can assume 64 values per each

combination of codes and modulation

The number of transmission formats is

2 modulations x 15 codes x 64 block dimensions = 1920

The code rates different from 1/3 (or 1/2) are obtained with

puncturing

with 15 codes, 16-QAM modulation and lower error protection, the

peak bit rate is 14 Mbit/s



Transmission formats

0,25 0,50 0,75 1,00

0,1

1

10

V e l o

c i t à d i T r a s m i s s i o n e [ M b i t / s ]

Rate di Codifica

1 Codice

2 Codici5 Codici

10 Codici

15 CodiciQPSK

16-QAM

0,25 0,50 0,75 1,00

0,1

1

10

V e l o


Rate di Codifica

1 Codice

2 Codici5 Codici

10 Codici

15 Codici

0,25 0,50 0,75 1,00

0,1

1

10

V e l o


Rate di Codifica

1 Codice

2 Codici5 Codici

10 Codici

15 Codici

0,25 0,50 0,75 1,00

0,1

1

10

V e l o


Rate di Codifica

1 Codice

2 Codici5 Codici

10 Codici

15 CodiciQPSK

16-QAM





Example of transmission formats

Modulation Transport block dimension

Block [bit]

TTI [ms] Coding

Rate

Bit Rate [Mbit/s] Number of codes

QPSK (R99) 3840 (12 blocchi di 320 bit) 10 1/3 0,384 1 (SF=8)

QPSK (R99) 20480 (32 blocchi di 640 bit) 10 1/3 2 3 (SF=4)

QPSK 317 2 1/3 0,16 1 (SF=16)

QPSK 461 2 1/2 0,23 1 (SF=16)

QPSK 931 2 1/2 0,46 2 (SF=16)

QPSK 1483 2 1/2 0,74 4 (SF=16)

QPSK 2279 2 1/2 1,14 5 (SF=16)

QPSK 3319 2 ∼0,7 1,65 5 (SF=16)

16-QAM 3565 2 ∼0,4 1,8 5 (SF=16)

16-QAM 4664 2 1/2 2,3 5 (SF=16)

16-QAM 7168 2 3/4 3,6 5 (SF=16)

16-QAM 11418 2 3/4 5,7 8 (SF=16)

16-QAM 14411 2 3/4 7,2 10 (SF=16)

16-QAM 17237 2 3/4 8,6 12 (SF=16)

16-QAM 21754 2 3/4 10,9 15 (SF=16)

16-QAM 25558 2 ∼0,9 12,8 15 (SF=16)

16-QAM 28776 2 1 14,4 15 (SF=16)

i.



Classes of terminals

The classes of terminals are defined basing on:

1) The number of codes that can be elaborated per each TTI

2) The maximum sustained bit rate, calculated on the whole

frame

3) The minimum interval between two subsequent TTI,

expressed in TTI

4) Handled modulations (only QPSK, or QPSK and 16-QAM)

3) Dimension of memory for HARQ





HSDPA – mobility handling

The mobile can stay in Cell_DCH state, applying Soft Handover

at the associated DCH

NodoBNodoB

Cell 1NodoBNodoB

Cell 2

HS-DSCH

DCH associatedDCH associated

Radio connections at instat T



HSDPA – mobility handling

The mobility procedure that transfers the connection on the HS-DSCH to the target cell iscalled Serving HS-DSCH Cell Change

It is activated from the RNC on the basis of terminal measurements

NodoBNodoB

Cella 1NodoBNodoB

Cella 2

HS-DSCHDCH Associato

DCH Associato

Radio connections at instant T+T 0





HSDPA – Network impact

Adaptive resource allocation algorithms for HSDPA

HW on Node B: new baseband elaboration to handle new coding

schemes and modulation (Channel Card, RAXB e TXB)

HW on RNC: new radio protocols elaboration algorithms and Iub

interface

Amplifiers: necessary a back-off of 1,5-2 dB for 16-QAM

New capacity on Iub, Iu

1 UMTS Ms Radio1

Documents

Transcript of 1 UMTS Ms Radio1