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WCDMA for UMTS


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All Rights Reserved Alcatel-Lucent @@YEAR

9300 W-CDMA UA06 R99 Radio PrinciplesWCDMA for UMTS

2 3

1 Context

1.1 Historical

Early 70s

CDMA developed for military field for its great qualities of privacy (lowprobability interception, interference rejection)

1996CDMA commercial launch in the US

This system called IS-95 or cdmaOne was developed by Qualcomm and has

reached 50 million subscribers worldwide

2000IMT-2000 has selected three CDMA radio interfaces:

- WCDMA (UTRA FDD)

- TD-CDMA (UTRA TDD)

- CDMA 2000

In the following material we will only refer to WCDMA (UTRA FDD)


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2 4

1 Context

1.2 Advantages & Disadvantages

CDMA is very attractive:

Better spectrum efficiency than 2G systems

Suitable for all type of services (circuit, packet) and for multi-services

Enhanced privacy

Evolutionary (linked with progress in signal processing field)

BUT:

Complex system: not easy to configure and to manage

Unstable in case of congestion


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2 5

1 Context

1.3 3GPP

The 3GPP is the organization in charge of the standardization of the

UMTS.It is made of standardization organization (ETSI in Europe, T1 in USA,ARIB in Japan or CTWS in China ), member of manufacturers andoperators.

The UMTS frequency allocations are :

TDD FDD MSS TDD

1900 1980 2010 20251920

MSSFDD

2110 2170 2200

FDD: Frequency Division Duplex

TDD: Time Division Duplex

MSS: Mobile Satellite SystemUplink Downlink


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2 6

2 Analogy


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2 7

Cell

Restaurant room

2 Analogy

2.1 WCDMA and Restaurant

WCDMA Restaurant Room

UE

People at table

Code

Language

Enjoy yourmeal !

Code 1

Code 2

Gutenappetite !

Bon appetit!

Bomapetite !

Ues, like people, sendand receive on thesame time and thesame frequency. Theyare separeted by:

For a table, the conversations of the neighbours

are noise, for a UE it is the same principle:

neighbour conversations are interference


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2 8

2 Analogy

2.1 WCDMA and Restaurant [cont.]


Node B

Steward

Downlink

Who have orderthis cake ?

????

???Impacts:

Power Control in DL

Control Admission

Very important !

Interference level in DL

problem:

If some UE use too muchpower

If there are too manyusers in the cell

Enjoy yourmeal !

COMOESTAS ?


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2 9

2 Analogy

2.1 WCDMA and Restaurant [cont.]


It is for me!

Who have orderthis cake ?

QUIERO LATARTA!!

Es istmeine

Uplink

Cest la

pomme ?

????

At the Node B level:

If a UE, close to the NB,speak too loud

If there are too manyusers

Problem of interferencelevel too high.

The NB cant decode any

users anymore.

Impacts:

Power Control in UL

Admission Control

Very important


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2 10

3 Spread Spectrum Modulation


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2 11


3.1 A Code as a Shell against Noise

The letter A represents the signal to transmit over the radio interface.

At the transmitter the height (ie the power) ofA is spread, while a color

(i.e a code) is added to A to identify the message .

At the receiver A can be retrieved with knowledge of the code, even if

the power of the received signal is below the power of noise due to theradio channel.

ReceiverTransmitter

Spreading

Noise

DespreadingRadio Channel


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2 12


3.2 Spectrum spreading

At the transmitter the signal is multiplied by a code which spreads thesignal over a wide bandwidth while decreasing the power (per unit of

spectrum).

At the receiver it is possible to retrieve the wanted signal by multiplying

the received signal by the same code: you get a peak of correlation,while the noise level due to the radio channel remains the same, because

this is not correlated with the code.

But the interference level is too high, it is not possible to decode any

message.

???

f

P

Spreading

Radio channel

Despreading

Interference Level

f

P

f

P

f

P


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2 13


3.3 Transmission Chain

Air Interface

The narrowband data signal is multiplied bit per bit by a code sequence:

it is known as chipping.

The chip rate (fixed) of this code sequence is much higher than the bit

rate of the data signal: it produces a wideband signal, also called spread

signal.

At the receiver the same code sequence in phase should be used toretrieve the original data signal.

Modulator Demodulator

Code Sequence

Data Data

Code sequence

NB-Signal WB-Signal NB-SignalWB-Signal


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2 14


3.4 Code & Spreading factor

The code is applied on each bit of the user data.

The Spreading Factor, called SF, is the length of this code.

Example: Data to transmit: 1 0 , SF=8.

1

-1

1

-1

Spread data

Code

Coded data

Tr

ansmission

Reception

Received data,

without error

1

-1

A chip

Chip rate fixed at 3.84 Mchip/s

Code applied

1

-1

1

-1

1

-1


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2 15


3.5 Spreading factor & Data Rate

The chip rate is fixed, 3.84 Mchip/s.

If the SF is divided by 2, the data rate is multiplied by 2 !


Spread data

Code

Coded data

Tr

ansmission

Reception

Received data,

without error

Code applied

Received

data

Small SF = High data rate

High SF = Small data rate

1

-1

1

-1

1

-1

1

-1

1

-1

1

-1


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2 16


3.6 Spreading factor & Error at reception

When an error occurs at the reception, the determination of the bit value is less trivial.


1

-1

1

-1

Signal sent onthe air

Signal receivedwith error

Code

SF=8

Zoom

onthedecoded

signal

Decoded data

1

-1

0

The

determination ofthe bit value is

based on the area

of the received

signal.

Here is 6 areaunits over 8


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2 17


3.6 Spreading factor & Error at reception [cont.]

1

-1

1

-1

Signal sent onthe air

Signal receivedwith error

Code

SF=4

Zoomonthe

decodedsignal

Decoded data

1

-1

0

The

determination ofthe bit value is

based on the area

of the received

signal.

Here is 2 areaunits over 4

With a small SF, the signal is more sensitive to errors.So to have the same error ratio you use more power

If you need a high data rate(video downloading), you

will use a small SF. You willhave more errors on your

message. So if you want to

keep the same error ratio,

you will use more power totransmit your message

To keep in mind


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2 18


3.7 Exercise: Orthogonal Code

Here, there is a received signal and two orthogonal codes

Could you apply these codes on the received signal and determinate whichcode has been used to spread the signal? What could you conclude about theorthogonality?

Received signal

Code 1

Decoded signal

1

Code1

Code2

Code 2

1

-1

1

-1

1

-1

1

-1

1

-1

1

-1

Received signal

Decoded signal

2


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2 19


3.7 WCDMA, Power Density & Processing Gain

RSSI: Received Signal Strength IndicatorTotal received wideband power over 5

MHz including thermal noise

ISCP (No): Interference Signal CodePower

Interference on the received signal

RSCP (Ec): Received Signal Code Power

Unbiaised measurement on the received

signal on one channelization code

Eb : energy per useful bit

PG : Processing Gain = Eb-Ec (in dB)

Power Gain after despreading. PG= 20 log (SF) f

P

RSSI or Io

ISCP or NoSIR

PG

Eb

RSCP or Ec

At Node B reception level

Wss

Ws


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2 20

Depending on the service, more or less

errors are allowed. UTRAN computesthe error ratio and then set the SIR

required for the service.

What are the modifications on the

diagram if:

The number of users increases ?The SF decreases ?

SIR: Signal Interference Ratio

No

RSCPSFSIR

.


3.7 WCDMA, Power Density & Processing Gain [cont.]

f

P

RSSI or Io

ISCP or NoSIR

PG

Eb

RSCP or Ec


Wss

Ws


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2 21

4 Code Division Multiple Access

4 C d Di i i M l i l A


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2 22


4.1 One-cell reuse

The area is divided into cells, but the entirebandwidth is reused in each cell (frequency

reuse of one)

> Inter-cell interference

> Cell orthogonality is achieved by codes

The entire bandwidth is used by each user at the

same time

> Intra-cell interference

> User orthogonality is achieved by codes

4 C d Di i i M lti l A


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2 23


4.2 Multiple access

All the users transmit on the same 5 MHz carrier at the same time and

interfere with each other.

At the receiver the users can be separated by means of (quasi-

)orthogonal codes.

Transmitter 2

Spreading 1

Spreading1

Spreading 2 Receiver

Radio ChannelTransmitter 1

The receiver aims at receiving Transmitter 1 only.



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2 24


4.2 Multiple access [cont.]

If a user transmits with a very high power, it will be impossible for the

receiver to decode the wanted signal (despite use of quasi-orthogonalcodes)

CDMA is unstable by nature and requires accurate power control.

Transmitter 2

Receiver

Radio ChannelTransmitter 1

The receiver aims at receiving Transmitter 1 only.

Spreading 1

Spreading1

Spreading 2



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2 25


4.3 Spreading: Channelization and Scrambling

2chc

3chc

1chc

scramblingc

The channelization code (or spreading code) is signal-specific: the codelength is chosen according to the bit rate of the signal.

The scrambling code is equipment-specific.

air

interfaceModulator



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2 26


4.4 Channelization Codes (Spreading Codes)

The channelization codes are OVSF (Orthogonal Variable Spreading Factor)codes:

their length is equal to the spreading factor of the signal: they can

match variable bit rates on a frame-by-frame basis. orthogonality enables to separate physical channels:

UL: separation of physical channels from the same terminal

DL: separation of physical channels to different users within one cell

SF = 1

C ch,1,0 = (1)

C ch,2,0 = (1,1)

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

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

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

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

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

SF = 4SF = 2 SF = 8

The code tree is shared by severalusers (usually one code tree per

cell)



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2 27


4.5 Scrambling codes

The scrambling codes provide separation between equipment:

UL: separation of terminalsNo need for code planning (millions of codes!)

There are 224 long and 224 short scrambling codes in uplink

DL: separation of cells

Need for code planning between cells (but trivial task)There are only long scrambling codes in downlink

(512 to limit the code identification during cell search procedure)

The long scrambling codes are truncated to the 10 ms frame length.

Only one DL scrambling code should be used within a cell.

Another scrambling code may be introduced in one cell if necessary

(example : shortage of channelization code), but orthogonality between

users will be degraded.


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2 28

5 Soft Handover

5 Soft Handover


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2 29

5 Soft Handover

5.1 Introduction

Principle: As the UEs are separated by codes, they send and receive data at the

same time and on the same frequency and one frequency is used in a set of adjacentcells, the soft handover is possible.

A UE is in case ofSoft Handover when it is linked to several cells at the same time.

So , in downlink, the UE receives several time the same data and combine them to

increase the quality. In Uplink, a Node B can receive the same message from several

cells and combines them to increase the quality.

Soft Handover doesnt exist in GSM, it is not possible because there are

different frequencies in a set of adjacent cells.

Interest: Asthe quality of the signal is increased afterthe reception, it is possible to use less power. That

allows to save the interference level.If thisinterference level is too high, it is not possible to

decode the data and the call is drop.

5 Soft Handover


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2 30

5 Soft Handover

5.2 Scenarios: Softer Handover

Iu

Core Network

Iubs Iubs

Iur

Iu

Serving RNC

5 Soft Handover


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9300 W-CDMA UA06 R99 Radio PrinciplesWCDMA for UMTS2 31

5 Soft Handover

5.3 Scenarios: Soft Handover

Iu

Core Network

Iubs Iubs

Iur

Iu

Serving RNC

5 Soft Handover


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5 Soft Handover

5.4 Scenarios: Soft Handover inter RNC

Iu

Core Network

Iubs Iubs

Iu

Serving RNC Drift RNCIur

5 Soft Handover


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5 Soft Handover

5.5 Scenarios: SRNC Relocation

Iu

Core Network

Iubs Iubs

Iu

Serving RNC Drift RNCServing RNCIur

5 Soft Handover


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In Downlink,

Scrambling Code

One DL SC per Cell

Channelization Code

One DL CC per radio link to avoid having the

same code sequence on 2 radio links

In Uplink, Scrambling Code

One UL SC per UE

Channelization Code

One UL CC per service (per physical

channel).

The UE sends one signal which can be

received by several cells.

The UE receives several signals

Conclusion:

5 Soft Handover

5.6 Soft Handover & Code Management

Iu

Core Network

Iubs

Serving RNC

CellA Cell B

DL SC cellA

DL CC1 user 1

DL SC cellB

DL CC2 user 1

UL SC eqUL CC user

5 Soft Handover


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Why do we need soft HO?Imagine that a UE penetrates from one cell deeply into an adjacent cell:

it may cause near-far effect

hard HO is not a good solution, due to the hysteresis mechanism

Better spatial repartition of the power, so lower interference level

Additional resources due to soft HO:- Additional rake receiver in Node-B

- Additional Rake Fingers in UE

- Additional transmission links between Node-Bs and RNCs

Soft HO provides Diversity (also called Macro-Diversity), but requiresmore network resource.

5.7 Cost & Benefit

5 Soft Handover


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Soft Handover execution:

Soft Handover is executed by means of the following procedures Radio Link Addition (FDD soft-add);

Radio Link Removal (FDD soft-drop);

Combined Radio Link Addition and Removal.

The cell to be added to the active set needs to have information forwardedby the RNC:

Connection parameters (coding scheme, layer 2 information, )

UE ID and uplink scrambling code,

Timing information from UE

The UE needs to get the following information

Channelization & scrambling codes to be used

Relative timing information (Timing offset based on CPICH synchro)

5.7 Cost & Benefit [cont.]


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6 Rake Receiver

6 Rake Receiver


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6.1 Rake Receiver principle

In a CDMA system there is a single carrier which contains all user signals.

Decoding of all these signals by one receiver is only a question of signal

processing capacity.

A Rake receiver is capable to decode several signals simultaneously in

the so called fingers and to combine them in order to improve thequality of the signal or to get several services at the same time.

A Rake receiver is implemented in mobile phones and in base stations.

A Rake receiver can provide:

- multi-service (via handling of multiple physical channels that arecarrying the services)

- soft handover- path diversity

6 Rake Receiver


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6.1 Rake Receiver principle [cont.]

The components of the multi-code signal are demodulated in parallel each

in one finger of the Rake Receiver.

The outputs of the fingers:

can provide independent data signals

can be combined to provide a better data signal(s)

Delay 1Code Sequence 1

Code Sequence 2 or 3

Code Sequence 2Delay 2

Delay 3

Data 2

1st

Finger

2nd

Finger

3rd

Finger

Data 1

Multi-codesignal

Delay Adjustment

6 Rake Receiver


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6.2 Rake Receiver and Multi-Service

As a first approach, we can say:

One service, one code! (*)

Multimedia receiverTransmitter

Spreading 1 Despreading 1

Radio ChannelSpreading 2

Despreading 2

>> Which codes make it possible to

separate the two signals at the

receiver?

6 Rake Receiver

6 3 R k R i d f h d


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6.3 Rake Receiver and soft handover

Soft handover is possible, because the two mobile stations use the same

frequency band. The mobile phone need only one transmission chain to

decode both simultaneously.

Base Station 2

Spreading 1

Despreading 1&2

Spreading 2 Mobile phone

Radio ChannelBase station 1

>> Which codes make it possible to

separate the two signals at the

receiver?

6 Rake Receiver

6 4 R k R i d P h Di i


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6.4 Rake Receiver and Path Diversity

Natural obstacles (buildings, hills) cause reflections, diffractions and

scattering and consequently multipath propagation.

The delay dispersion depends on the environment and is typically:

1 s (300 m) in urban areas 20 s (6000 m) in hilly areas

The delay dispersion should be compared with the chip duration 0,26 s (78 m)

of the CDMA system.

If the delay dispersion is greater than the chip duration, the multipathcomponents of the signal can be separated by a Rake Receiver.

In this case, CDMA can take advantage of multipath propagation.

6 Rake Receiver

6 4 R k R i d P th Di it [ t ]


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6.4 Rake Receiver and Path Diversity [cont.]

Dispersion > Chip duration

The Rake Receiver can provide path diversity to improve the quality of the signal.

ReceiverTransmitter

Spreading

Direct path

Reflected path

ReceiverTransmitter

Spreading Despreading

Direct path

Reflected path

Dispersion > Which codes make it

possible to separate the two

signals at the receiver?

Despreading


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7 Power Control

7 Power Control

7 1 Wh ?


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SIR

7.1 Why ?

Iub

Serving RNC

Main Problem : If the interference level is to high, it is not possible to decode the signal.

f

P

ISCP or No

PG

Eb

RSCP or Ec


SIR

7 Power Control

7 2 Diff t ki d f P C t l


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Physical channels:

Not associated with transport channels

(Physical signaling)

Associated with transport channels

Dedicated channels

Common channels

7.2 Different kinds of Power Control

Channel power fixed and set by the

operator

Channel power fixed and set by theoperator

Open Loop Power Control

Closed & Open Loop power control

7 Power Control

7 3 O L P C t l


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7.3 Open Loop Power Control

The Open Loop Power Control is used to set the initial transmit power when: The UE requests a RRC Connection,

The UE sends the first dedicated radio frame,

The Node B sends the first dedicated radio frame.

Based on CPICH measurements

Based on UE measurement reports

CPICH

Initial Access

First dedicated Radio Frame

Measurement reports

First dedicated Radio Frame

7 Power Control

7 4 Closed Loop Power Control: Principle


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Iub

RNC

Outer Closed LoopInner Closed Loop

SIR Estimation

Comparison

between SIRest andSIRtarget

Generation of a TCP

command: increaseor decrease

On each Time slot !

(1500 Hz)...

Power down

Power up

Power down

Power ...

***

***

SIR target

Errormeasurements

The Node-B controls the power of the UE (and vice versa) by performing a SIR estimation (inner loop) andby generating TPC command for each time slot of the radio frame.

The RNC controls parameters of the SIR estimation (outer loop) and set the initial SIR target, defined bythe operator and modify it according to the error measurement reports.

Closed Loop Power Control

7.4 Closed Loop Power Control: Principle

***

***

***

***

7 Power Control

7 4 Closed Loop Power Control: Power Density


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Iub

Assuming a user using a service.

It is initial SIR target is 3dB.

The error ratio required is 0.01 .

Several error ratio reports are between 0.002

and 0.007

How do the SIR target evolve ?

What is the impact on the user or on thesystem if the estimated SIR is too high ? Toosmall ?

7.4 Closed Loop Power Control: Power Density

RNC...

Power up

Power ...

SIR target

Errormeasurement

s

ISCP or No

f

P

SIRest

Eb

RSCP or Ec


SIRTarget

7 Power Control

7 5 UL Closed Loop PC in case of Soft Handover


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What is the behavior of the UE in UL in case ofsoft handover ?

The UE takes in to account all the command

according to the 3GPP

P(t)=P(t-1) + F(TPC1(t) + TPC2(t))

The function F(TPC(t)) is implemented by the UE

manufacturer.

F(TPC(t))=min(TCP1(t), , TPCi(t))

With i= number of involved Node B

7.5 UL Closed Loop PC, in case of Soft Handover

Iub

Power up !!!

TPC=1

Power down !!!

TPC=-1

???

1 2

7 Power Control

7 5 DL Closed Loop PC in case of Soft Handover


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Iub

What is the behaviour of the Node B involed

in the call in DL in case of soft handover ?

The UE sends the same command for all

the Node B involved.

Node Bs must transmit data with the same

power for a user

Due to reception errors their power can

shift themselves

A mechanism, the DL Power Balancing,allows to readjust the transmission power of

the Node B.

The SRNC selects the best radio link, andreadjust, step by step, the transmission

power.

P(t) = P(t-1) + Ptpc(t) + Pbal(t)

Power up !!!TPC=1

Power

up

Power

up

7.5 DL Closed Loop PC, in case of Soft Handover


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8 Capacity, Coverage & Quality

8 Coverage, Capacity & Quality

8 1 Links between Coverage Capacity and Quality


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8.1 Links between Coverage, Capacity and Quality

Example: Increase the quality in UL

How to do ?

Decrease the error ratio at the Node B level

So increase the SIR at the Node B level

So the UEs use more power

Impacts !

Increase the UL Interference level

So decrease of the cell size

And decrease the capacity of the cell.

RNC

Node B

Iub

f

P

SIR

SIR


8 2 Improvement Ways


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8.2 Improvement Ways

AMR speech Codecit enables to switch to a lower bit rate if the mobile is moving out of thecell coverage area: it is a trade-off between quality and coverage.

Multipath diversityit consists of combining the different paths of a signal (due to reflections,

diffractions or scattering) by using a Rake Receiver.

Multipath diversity is very efficient with W-CDMA.

Soft(er) handoverthe transmission from the mobile is received by two or more base stations.

Receive antenna diversitythe base station collects the signal on two uncorrelated branches. It can be

obtained by space or polarization diversity.

Base stations algorithmse.g. accuracy of SIR estimation in power control process


8 3 Typical Values


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8.3 Typical Values

Quality: The quality is measured with the Block Error Ratio (BLER). Here some example according

different services.

Coverage:

Dense Urban Cell: about 300 meters

SubUrban Cell: about 1 km

Rural Cell: 3 km

Capacity:The main limitation is the interference level due to the WCDMA technology.

But the system is also limited by capacity processing of the Node B and the RNC, by the codes, and by

the transmission capacity.

AMR CS64 PS64 PS128 PS384 DCCH

TargetBLER

0.001 0.01 0.001 0.01 0.1 0.01 0.01 0.01 0.01


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1 Logical Architecture


1 1 UTRAN Situation & Core Network in 3GPP R4


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1.1 UTRAN Situation & Core Network in 3GPP R4

Core Network

PS-CN

Access Network

Iu-PS

External Networks

HLR

PSTN

IN network

UTRAN

RNC

Node B

PDN

CS Links

PS Links

Gb

Backbone

iGGS

N

SGSNGSM

BSS

BSC

BTSPCU

CS-CN

MSC Server

MGWGMSC

Iu-CS


1 2 UTRAN Logical Architecture


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1.2 UTRAN Logical Architecture

Core Network

UTRAN

UE

Iub Iub

Iu-CS Iu-PS

Iur

Uu Interface

RNS

CS-CN PS-CN

RNC RNC

Node B Node B

UEs


1 3 Interfaces


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1.3 Interfaces

Open Interfaces:

The function of the Network Elements have been clearly specified by the

3GPP.

Their internal implementation issues are open for the manufacturer

All the interfaces have been defined in such a detailed level that the

equipment at the endpoints can be from different manufacturers.Open Interfaces aim at motivating competition between manufacturers.

Physical implementation of Iu interfaces

Each Iu Interface may be implemented on any physical connection using

any transport technology, mainly on E1 (cable), STM1 (Optic fiber) andmicro-waves.

ATM will be provided in the 3GPP R4 release and IP is for the 3GPP R6


1 4 Network Element Function


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1.4 Network Element Function

RNC: Radio Network ControllerIt is the intelligent part of the UTRAN:

- Radio resource management (code allocation, Power Control, congestion

control, admission control)

- Call management for the users

- Connection to CS and PS Core Network- Radio mobility management

Iub IubIur

RNS

Node B Node B

RNC RNC


1 4 Network Element Function [cont ]


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1.4 Network Element Function [cont.]

Node-B

A Node-B can be considered, as first approximation, like a transcoder

between the data received by antennas and the data in the ATM cell on the

Iub.

- Radio transmission and reception handling

- Involved in the mobility management

- Involved in the power control

Iub

RNC

Node B

ATM Transport

Technology


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2 Network Protocols

2 Network Protocols

2.1 Protocols in UTRAN


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2.1 Protocols in UTRAN

Uu Interface

Core Network

RNC RNC

Node B

Iub

Iu

Iur

Iu Protocols

The Iu protocols Used to exchange data (traffic

and signaling) between RNCs,Node Bs and the Core Network.

Radio Protocols

The Radio protocols Used to process the data sent on

the air and for the signalingbetween UTRAN and the UEs

NAS Signaling Signaling between a UE and

the Core Network. Typically, the Authentification

and the Location

NAS Signaling

2 Network Protocols

2.2 Protocol Stack on the Interfaces based on ATM


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Iub

Iub

Iur

Iu- PS

Iu- CS

Node B

RNC

RNC

RNSAP

RANAP

RANAP

Iu UP

Voice

Iur FP

Iu UP

Data

Control plane User plane

Iub

Node B

CS-CN

PS-CN

RadioSig Voice

NBAPIub FP

Radio

Sig Voice Data

AAL5 AAL2

ATM

AAL5 AAL2

ATM

AAL5 AAL2

ATM

AAL5 AAL5

ATM

Data

Node B


2.2.1 General model


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The same general protocol model is applied for all Iu interfaces:

Application Protocols:

Radio

Network

Layer

Transport

Network

Layer

Physical Layer

Signaling

Bearer(s)

Signaling

Bearer(s)

Data

Bearer(s)

ALCAP

Application

ProtocolData

Stream(s)

Transport Network

Control PlaneTransport Network

User Plane

Transport Network

User Plane

Control

PlaneUser Plane

- NBAP for Iub interface

- RNSAP for Iur interface

- RANAP for Iu-CS and Iu-PS interfaces

1. What is the

purpose of the

separation between

the Radio Network

Layer and the

Transport Network

Layer?

2. Why is ALCAP

protocol

necessary?

2.2.1 General model


2.2.2 Iub protocols


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ATM

Radio

Network

Layer

Transport

Network

Layer

Physical Layer

AAL5 AAL2

ALCAP

NBAPFrame

Protocols

(IubFP)

Control Plane User Plane

AAL5

RRC Connection

Establishment*

Radio Link

Establishment

RABs* NAS signalling*

Transport Network

Control Plane

Transport Network

User Plane

Transport Network User

Plane

2.2.2 Iub protocols


2.2.3 Iur Protocols


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ATM

Radio

Network

Layer

Transport

Network

Layer

Physical Layer

...

AAL5 AAL2

ALCAP

RNSAPFrame

Protocols

(Iur FP)

Control Plane User Plane

AAL5

RRC Connection

Establishment*

Establishment of an

additional radio link

to an UE

(for soft HO)

RABs* NAS signalling*

Transport Network

Control Plane

Transport Network

User Plane

Transport Network User

Plane

2 Network Protocols

2.3 Protocol Stack on the Interfaces based on IP


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Characteristics

Optimized HSPA Offload Hybrid Iub

RNC

Node B

R99 over ATM

E1 Leased

Lines

Ethernet

HSPA over

IPLow CostBackhaul

GigE

STM

E1/T1andEth

SGSN

MSC Server

CS over ATM

PS over Eth

IP Evolution in UA06


UTRAN Interfaces Based on IP (User Plane)


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( )

Voice

AAL2

ATM

Physical

Data

UDP / IP

ETH

Physical

GTP-uVoice

AAL2

ATM

Physical

Data

UDP / IP

ETH

Physical



UTRAN Interfaces Based on IP (Control Plane)


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( )

RANAP

IP

ETH

Physical

M3UA

SCTP

SCCP

NBAP

AAL5

ATM

Physical

ALCAP

AAL5



70/149



3 Radio Channels

3 Radio Channels

3.1 Global Situation


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UTRAN SGSN GGSN PDNInternet

UMTS Bearer Service External BearerService

UMTS Bearer Service

Radio Access Bearer Service(RAB) CN BearerService

BackboneBearer Service

Iu BearerService

Radio BearerService

Uu Iu

Teleservice

UE

Logical

Channel

TransportChannel

Physical

Channel

3 Radio Channels

3.2 RAB Presentation


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2 73

The RAB provides confidential transport of signaling and user data

between UE and CN with the appropriate QoS.

UTRAN

UE UMTS Bearer

UMTS Bearers

RABs (mapped on Radio & Iu Bearers)

CN-CS

CN-PS

Radio Bearers Iu Bearers

UMTS Bearer

UMTS bearer

services

3 Radio Channels

3.3 Radio Channels, Protocols & Network Elements


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2 74

RRC

RLC

MAC

BMCPDCP

Physical Layer Physical Layer

NAS

Signaling

RRC

Sig.

VoiceWeb

BrowsingSMS Cell

Broadcast

RadioBearers

Traffic

Logical Ch.

Transport

Channels

Uu Interface

RNC Node B UE

Physical Channels

MAC

Transport

Channels

Control

Logical Ch.

3 Radio Channels

3.4 Radio Bearers


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2 75

Signaling Radio Bearers (SRB)

SRBs can carry:

- layer 3 signaling (e.g. RRC connection establishment)

- NAS signaling (e.g location update)

There can be up to 4 SRBs per RRC connection (one UE has one RRC

connection when connected to the UTRAN).

User Plane Radio Bearers

RABs are mapped on user plane RBs.

One RAB can be divided on RAB sub-flows and each sub-flow is mapped on

one user plane RB.

e.g the AMR codec encodes/decodes speech into/from three sub-flows; each

sub-flow can have its own channel coding.

3 Radio Channels

3.5 Logical Channels


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2 76

Control Channels (CCH)

Broadcast Control Channel (BCCH)

Traffic Channels (TCH)

Paging Control Channel (PCCH)

Dedicated Control Channel (DCCH)

Common Control Channel (CCCH)

Dedicated Traffic Channel (DTCH)

Common Traffic Channel (CTCH)

UTRAN UELogical Channels

3 Radio Channels

3.5 Logical Channels [cont.]


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2 77

UL ( )

/DL ( )

What type of information?

BCCH System control information

e.g cell identity, uplink interference level

PCCH Paging information

e.g CN originated call when the network does not know the

location cell of the UECCCH Control information

e.g initial access (RRC connection request), cell update

DCCH Control information (but the UE must have a RRC connection)

e.g radio bearer setup, measurement reports, HO

DTCH Traffic information dedicated to one UE

e.g speech, fax, web browsing

CTCH Traffic information to all or a group of UEs

e.g SMS-Cell Broadcast

3 Radio Channels

3.6 Why Transport Channels?


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2 78

A transport channel offers a flexible pattern to arrange information on any

service-specific rate, delay or coding before mapping it on a physical

channel:

it provides flexibility in traffic variation

it enables multiplexing of transport channels on the same physical channel

Transport channels provide an efficient and fast flexibility in radio

resource management.

Time

Traffic

Time Interval

Transport

Channel

3 Radio Channels

3.7 Structure of a Transport Channel


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2 79

168

168

168

168

168

168

168 bits

20 ms

Time Transmission

Interval (TTI): periodicityat which a Transport Block

Set is transferred by the

physical layer on the radio

interface

20 ms

Transport Block: basic

unit exchanged over

transport channels.

Transport Format (TF): it may be changed every TTI. Each

TF must belong to the Transport Format Set (TFS) of the

transport channel

168

168

>> The system delivers one Transport Block Set to thephysical layer every TTI: what is the delivery bit rate of the

transport blocks to the physical layer during the first TTI?

20 ms 20 ms

3 Radio Channels

3.7 Structure of a Transport Channel [cont.]


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2 80

Transport Format (TF)

Semi-static part (can be changed, but long process)

Transmission Time Interval (TTI),

Coding scheme...

Dynamic part (may be changed easily)

Size of transport block,

Number of transport blocks per TTI

Transport Format Set (TFS)

It is the set of allowed Transport Formats for a transport channel, which is

assigned by RRC protocol entity to MAC protocol entity.

MAC chooses TF among TFS.MAC may choose another TF every TTI without interchanging with RRC

protocol (fast radio resource control).

3 Radio Channels

3.8 Transport Channels: Example


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2 81

576

576

576

576

576

576

576 bits

576

576

40 ms

3. How many Transport Format(s) may be chosen for this transport channel?

4. Can you imagine why the transfer has been interrupted during the third TTI?

Static Part

TTI ?

Coding scheme Turbo coding, coding rate= 1/3

CRC 16 bits

Dynamic Part

Transport Block Size ?

Transport Block Size Set 576*B (B= 0,1,2,3,4)

1. Complete the table

2. What is the delivery

bit rate of the transport

blocks to the physical

layer during the first TTI?

3 Radio Channels

3.9 Transport Channels


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2 82

Common Channels

Broadcast Channel (BCH)

Dedicated Channels

Paging Channel (PCH)

Random Access Channel (RACH)

Forward Access Channel (FACH)

Dedicated Channel (DCH)

Common Packet Channel (CPCH)

Downlink Shared Channel (DSCH)

UTRAN Transport Channels UE

3 Radio Channels

3.10 Common Transport Channels


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2 83

BCH: Broadcast Channel

A downlink transport channel that is used to carry BCCH. The BCH is

always transmitted with high power over the entire cell with a low fixed bit

rate.

>> The BCH is the only transport channel with a single transport format (no

flexibility). Can you explain why?

PCH: Paging Channel

A downlink transport channel that is used to carry PCCH. It is always

transmitted over the entire cell.

>> Is it possible to carry all types of information on the PCH?

3 Radio Channels

3.10 Common Transport Channels [cont.]


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2 84

FACH: Forward Access Channel

A downlink transport channel that is used to carry control information. It may alsocarry short users packets. The FACH is transmitted over the entire cell or over only a

part of the cell using beam-forming antennas. The FACH uses open loop power

control (slow power control).

>> In which case is it interesting to use beam-forming antennas? would it also be

relevant to implement this feature for PCH?

RACH: Random Access Channel

An uplink transport channel that is used to carry control information from the mobile

especially at the initial access. It may also carry short user packets. The RACH is

always received from the entire cell and is characterized by a limited size data field,

a collision risk and by the use of open loop power control (slow power control).

>> Why is it interesting to carry short user packets on RACH in spite of limited data

field and collision risk (instead of using a dedicated channel)?

3 Radio Channels

3.10 Common Transport Channels [cont.]


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2 85

DSCH: Downlink Shared Channel

A downlink transport channel shared by several UEs to carry dedicated

control or user information. When a UE is using the DSCH, it always has

an associated DCH, which provides power control.

CPCH: Common Packet Channel

An uplink transport channel that is used to carry long user data packetsand control packets. It is a contention based random access channel. It is

always associated with a dedicated channel on the downlink, which

provides power control.

Transfer of signalling and traffic on a shared basis

3 Radio Channels

3.11 Dedicated Transport Channels


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2 86

DCH: Dedicated Channel

A downlink or uplink transport channel that is used to carry user or control

information. It is characterized by features such as fast rate change (on a

frame-by-frame basis), fast power control, use of beam-forming and

support of soft HO.

3 Radio Channels

3.12 Mapping Logical / Transport Channels


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2 87

Control Logical Channels

BCCH PCCH CCCH DCCH

Traffic Logical Channels

DTCH CTCH

BCH PCH RACH FACH DSCH CPCH DCH

Common Transport Channels Dedicated

Transport

Channels

3 Radio Channels

3.12 Mapping Logical / Transport Channels [cont.]


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2 88

Control Logical Channels

BCCH PCCH CCCH DCCH

Traffic Logical Channels

DTCH CTCH

BCH PCH RACH FACH DSCH CPCH DCH

Common Transport Channels Dedicated

Transport

Channels

3 Radio Channels

3.13 Physical Channels


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2 89

RNC

Node B

IubTransport

Channels

For the UE point of view, the network is just the physical channels.

There are several kinds of physical channels. Channel associated with transport channel

UTRAN Signaling (mobility management)

Core Network Signaling (authentication)

User Traffic (voice)

There are common and dedicated channels

Channels not associated with transport channel, the physical

signaling.

Cell Search Selection

System Information Collection

Connection Request and Paging Surveillance

These channels and resources allowing the UE to share these

channels with other users are the radio resources

We will see later how data from transport channel are processed to be

mapped on the physical channels and how a UE uses these channels.

3 Radio Channels

3.14 Physical Channel List


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2 90

Not associated with transport channels

CPICH: Common Pilot Channel

PICH: Page Indicator Channel

P-SCH & S-SCH: Primary & Secondary Synchronization Channel

AICH:Acquisition Indicator Channel

Common Physical Channels, associated with transport channels

P-CCPCH & S-CCPCH: Primary & Secondary Common Control Channel

PRACH: Physical Random Access Channel

PDSCH: Physical Downlink Shared Channel

PCPCH: Physical Common Packet Channel

Dedicated Physical Channels, associated with transport channels

DPDCH: Dedicated Physical Data Channel

DPCCH: Dedicated Physical Control Channel

3 Radio Channels

3.15 Downlink


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2 91

Logical Ch

Transport Ch

Physical Ch

AICHNot associated with

transport channels PICH CPICH P-SCHS-SCH

PDSCH S-CCPCH P-CCPCHDPDCH

+

DPCCH

DTCH, DCCH CCCH, CTCH

DCH BCHPCHFACHDSCH

Not implemented

yet in Alactel-Lucent

Solution

PCCH BCCH

DPDCH and DPCCH

multiplexed by time

Common Physical ChDedicated

Physical Ch

3 Radio Channels

3.16 Uplink


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2 92

Logical Ch

Transport Ch

Physical Ch

PRACH PCPCHDPDCH

+DPCCH

DTCH, DCCH CCCH

DCH1 RACHDCH2

CCTrCH

CPCH

DPDCH and DPCCH

multiplexed bymodulation

Dedicated Physical Ch Common Physical Ch

3 Radio Channels

3.17 Physical Channels: Structure


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2 93

A physical channel is defined by:

A carrier Some codes (see 4.3 and 4.4 part)

A start and stop instant

Physical channels are sent continuously on the air interface between start and stop instants.

15 Time

Slots

RadioFrame =10 ms

N bits

(according to the bit rate)

.

1 Time slot =

0.666 ms


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2 94

4 UTRAN Radio Protocols


4.1 Radio protocol stack


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2 95

Layer 3

Control plane User plane

Layer 2/MAC

Layer 1

Transport Channels

Bearers (called

RAB in user plane)Access Stratum

SAP

Non Access Stratum

control

cont

rol

control

PHY

MAC

RRC

Logical Channels

Layer 2/RLC

Radio Bearers

RLC RLCRLC

RLCRLC

RLCRLCRLC

PDCPPDC

P

BMCcontrol

control

Layer 2/PDCP

Layer 2/BMC

Physical Channels


4.2 Radio Resource Control (RRC)


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2 96

control

control

control

PHY

MAC

RRC

RLC

BearersCall management

Radio mobility management

Measurement control and reporting

Outer loop power controlRadio Bearers(control plane)

RRC is the brain of the radio interface protocol stack.

Layer 3

control

control

PDCP

BMC


4.3 PDCP and BMC Protocols


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2 97

PDCP (Packet Data Convergence Protocol)

- in the user plane, only for services from the PS domain

- it contains compression methods

In R99 only a header compression method is mentioned (RFC2507).

Why is header compression valuable?

e.g a combined RTP/UDP/IP headers is at least 60 bytes for IPv6, when IPvoice service header can be about 20 bytes or less.

BMC (Broadcast/Multicast Services)

- in the user plane

- to adapt broadcast and multicast services from NAS on the radio interface

In R99 the only service using this protocol is SMS Cell Broadcast Service

(directly taken from GSM).


4.4 Radio Link Control (RLC)


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2 98

Traffic

Logical

Channels

Radio Bearers

(user plane)Radio Bearers

(control plane)

RLC RLC

RLCRLCRLC

RLCRLCRLC

Control

Logical

Channels

Segmentation

Buffering

Data transfer with 3

configuration modes:- Transparent (TM)

- Unacknowledged (UM)

- Acknowledged (AM)

Ciphering

RLC provides segmentation and (in AM mode) reliable data transfer.

Layer 2/

upper part


4.5 Medium Access Control (MAC)


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2 99

TransportChannels

(common and

dedicated)

Basic data transfer

Multiplexing of logical channels

Priority handling/Scheduling

(TFC selection)

Reporting of measurements

Ciphering

MAC can switch a common channel into a dedicated channel if higher bit rate

is required (on request of L3-level).

MAC can change dynamically Transport Format (bit rate) of each transport

channel on a frame basis (each 10 ms) without interchanging with L3-level.

MAC provides flexible data transfer.

TrafficLogical

Channels

ControlLogical

Channels

MACLayer 2/

lower part


4.6 The Physical Layer


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2 100

Dedicated

Physical

Channels

Multiplexing of transport ch.

Spreading/modulation

RF processing

Power control

Measurements

Physical layer

Dedicated

Transport

Channels

The physical layer provides multiplexing and radio frequency

processing with a CDMA method.

Air Interface

Common

Transport

Channels

Common

Physical

Channels

Layer 1


100/149



2 101

1 Introduction to UTRAN Scenarios


1.1 Introduction


101/149



2 102

Iub

Serving RNC

CN

Collection of System Information

System

InformationRRC

Connection

RRC Connection

IMSI Attachment

IMSI

Attachment

Paging

Paging

The UE is switched on !

How can it retrieve network

parameters to request a service?


1.1 Introduction [cont.]


102/149



2 103

Iub

Serving RNC

CN

The UE requests a service.

How and in which conditions are the

resources required setup ?

Admission Control

? RAB Establishment

RAB


1.1 Introduction [cont.]


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2 104

Iub

Serving RNC

CN

The UE uses a service and moves !How UTRAN can provide the service despite

the mobility ?

A new radio link is added

Hard Handover on another FDD carrier

Inter RAT Handover

BSCBTS


104/149



2 105

2 Radio Channels Mapping


2.1 Downlink


105/149



2 106

Logical Ch.

Transport Ch.

Physical Ch.

AICHNot associated withtransport channels PICH CPICH P-SCH

S-SCH

PDSCH S-CCPCH P-CCPCHDPDCH +

DPCCH

DTCH, DCCH CCCH, CTCH

DCH BCHPCHFACHDSCH

Not implemented

yet in EvoliumTM

Solution

PCCH BCCH

DPDCH and DPCCH

multiplexed bytime

Common Physical Ch.DedicatedPhysical Ch.


2.2 Uplink


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2 107

Logical Ch.

Transport Ch.

Physical Ch.

PRACH PCPCHDPDCH +

DPCCH

DTCH, DCCH CCCH

DCH1 RACHDCH2

CCTrCH

CPCH

DPDCH and DPCCH

multiplexed bymodulation

DedicatedPhysical Ch.

CommonPhysical Ch.


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2 108

3 Service Request

3 Service Request

3.1 System Information Collection


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2 109

Principles

The UE synchronize itself at the

slot on the P-SCH

UE synchronize itself at the

frame level on the S-SCH andretrieve a group of 8 Scrambling

codes.

The UE test the 8 SC on the

CPICH to find the SC of the cell

The UE decode theBCH

channel

to read the system information

The UE select the best cell

Iub

Serving RNC

CN

???


3.1.1 P-SCH & S-SCH


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2 110

P-CCPCH Radio Frame 10 ms

Slot #0 Slot #1 Slot #14

acpP-SCH

S-SCH acs0

acp acp

acs2 acs14

The SCH is time-multiplexed with the P-CCPCH (which carries the BCH) and consists of 2 sub-channels.

The Primary SCH (P-SCH) made of always the slot on all the FDD Cells. The UE uses it to acquire the

slot synchronization to a cell.

The Secondary SCH (S-SCH) contains a sequence of 15 codes which identifies the Code Group of the

Downlink Scrambling Code (DL SC) of the cell. The UE uses it to acquire the frame synchronization to acell and to identify the Code Group of the DL SC.

256 chips


3.1.2 CPICH


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2 111

CPICH (Common Pilot CHannel)

The pilot carries a pre-defined symbol sequence at a fixed rate.

It is a reference:

To aid the channel estimation at the terminal (time or phase reference)

To perform handover measurements and cell selection/reselection (power reference)

The UE tests the 8 DL SC of the Group Code. The DL SC which allows to retrieve the pre-define

sequence is the DL SC of the cell.

Slot #0 Slot #1 Slot #14

Pre-defined symbol sequenceSF=256 Tslot=2560

chips 20 bits


3.1.3 System Information Broadcast


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2 112

The broadcast system information:

May come from CN, RNC or Node-B.

Contains static parameters (Cell identity, supported PLMN types...) and dynamic

parameters (UL interference level...).

Is arranged in System Information Blocks (SIB), which group together elements of

the same nature.

Some exemple:

SIB1: Core Network Information

SIB3: Cell Selection, Access Restriction

SIB7: UL Interference

SIB11: Measurement

CN

LA, RA

DL SC, Power Control info

UL interference level


3.1.3 System Information Broadcast [cont.]


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2 113

The broadcast system information can be carried on BCH which is transmitted permanently over

the entire cell.

Transport Ch.

Logical Ch.

Physical Ch.

BCCH

BCH

P-CCPCH

The broadcast system information is made of 128 periodic radio frame. So its period is 1280 ms.

There are a Master SIB or MIB and several SIB (System Information Block) organised by domain.

Frame #0 Frame #1 Frame #2

Frame #i-1 Frame #i Frame #i+1

Frame #125 Frame #126 Frame #127

MIB SIB3 SIB11

SIB5 SIB7 MIB

SIB5SIB11 SIB7

Thanks to this channel, the UE is able to retrieve information allowing the request of aRRC connection like the Channelization code used on the uplink common channel


3.1.4 Procedure


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2 114

System InformationUpdate Request

Master/Segment InfoBlock(s), BCCH

modification time

Master/Segment Info Block(s)

System Information (BCCH:BCH)

UE Node-B RNC

RRC RRC

NBAP

CN


System Information (BCCH:BCH)RRC RRC


System Information (BCCH:BCH)RRC RRC

System Information

Update ResponseNBAP NBAP

>> Why does RRC protocolterminate at Node-B for

BCH (not at RNC)?

NBAP


3.1.5 Radio Channel Mapping: P-CCPCH


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2 115

The Primary CCPCH carries the BCH, which provides system- and cell-specific information (e.g set of uplink scrambling codes)

The P-CCPCH is a fixed rate 30 kbps DL physical channel, which provide atiming reference for all physical channels (directly for DL, indirectly for

UL).

CCPCH is scrambled under the Primary Scrambling code.

Slot #0 Slot #1 Slot #13 Slot #14Slot #i

SCH

Tslot=2560 chips

20 bits

256 chips

Payload of 18 bits


3.1.6 Cell Selection Principle


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2 116

Now, the UE can read the BCH of one cell.

But this cell is not necessary the best becausethe SCH has been chosen randomly.

The UE compares the cells to be camped on thebest one.

There are 2 criterion:

QRxLev, from the CPICH RSCP, to estimate the

reception level.

Qqual, from the CPICH Ec/No, to estimate thequality of reception. It takes in account the

interference level.

When a UE is not connected, like here, and is

moving, it has to reselect regularly the best cellfor itself. To protect some cells, it is possible to

facilitate or not the selection of one cell.

Iub

RNC

CN

???

3 Service Request

3.2 RRC Connection


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2 117

Why?The UE is switched on and has selected a cell.

The UE is in idle mode.

UTRAN doesnt know anything about this UE.

The UE has neither UTRAN identifier nor

Scrambling and Channelization code.

The UE cant exchange any data with UTRAN.

To be known by UTRAN and to use dedicated radio

resources, the UE has to be RRC connected.

After, the UE can attach its IMSI or update its

location to the Core Network and can request a

service

Iub

RNC

CN

RRC Connected

3.2 RRC Connection

3.2.1 UE Status


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2 118

UE

detached

UE

in idle mode

UE

in connected

mode

RRC Connection Release

RRC Connection Establishment

out of coverage

just after switch on process

Including Cell search procedure

Just after the switch on, the UE has to attach its IMSI. Thanks to his procedure the Core Network

knows, the UE is on the network and where it is located at the Location or routing area level.

Several sub-status in theconnected

mode

To attach its IMSI and update its location the UE has to be in connected mode, so it

has to request a RRC Connection

3.2 RRC Connection

3.2.1 UE Status [cont.]


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2 119

Cell DCH

Cell FACH

URA PCH

Cell PCH

UE

in idle

mode

UE in connectedmode

Cell_DCH state

Signalling and traffic data

dedicated to the UE (mapped

on DCCH and DTCH

respectively) are carried on

DCH transport channel

Cell_FACH state

Signalling and traffic data

dedicated to the UE (mapped

on DCCH and DTCH

respectively) are carried onRACH (uplink) and FACH

(downlink) transport channels

Cell_DCH Cell_FACHNo traffic UL/DL at expiry of timer

Cell_FACH Cell_DCHTraffic volume UL/DL too large

3.2 RRC Connection

3.2.1 UE Status [cont.]


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2 120

Cell_PCH state

No transmission of signalling andtraffic data dedicated to the UE

(no DCCH and no DTCH)

But the RRC connection is still

active (UTRAN keeps RNTI for UE)

and UE location at a cell level.

- a DCCH (and possibly a DTCH) canbe reestablished very quickly (this

procedure is initiated by sending a

paging signal PCH)

URA_PCH state

Very similar to cell_PCH state

UTRAN keeps the location of the UE at

the URA level (set of UMTS cells)

Cell_PCH

Cell_FACH

URA_PCHToo many cell reselections

Cell_FACHCell_PCHNo traffic UL/DL at expiry of timer 2

Cell/URA_PCH Cell_FACHIncoming DL or UL traffic

Cell DCH

Cell FACH

URA PCH

Cell PCH

UE

in idle

mode

UE in connectedmode

3.2 RRC Connection

3.2.2 Procedure: RRC Connection Establishment


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2 121

Initial UE identity, Establishment cause, Initial UE capability

1. RRC Connection Request (CCCH:RACH)

UE

RRC RRC

3. Radio Link Establishment

Initial UE identity, RNTI, capability update requirement, TFS, TFCS, frequency, UL

scrambling code, power control info

4. RRC Connection Setup (CCCH:FACH)RRC RRC

Integrity information, ciphering information

5. RRC Connection Setup Complete (DCCH:RACH or DCH)RRC RRC

2. Allocate RNTI, Select Level

1 and Level 2 parameters

(e.g. TFCS, scrambling code)

>> Can the UE send user information (e.g voice call) after completing this stage?

Node-B RNC

3.2 RRC Connection

3.2.3 Procedure: RRC Connection: RRC Connection Release


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2 122

Node-B(DRNC)

SRNCDRNCNode-B(SRNC)

RRC RRC4. RRC Connection Release (DCCH:DCH )

Cause

RANAP RANAP

1. Iu Release

Command

Cause

RANAP RANAP

2. Iu Release

Complete

-

3. ALCAP Iu Bearer Release

RRC RRC5. RRC Connection Release Complete (DCCH:DCH )

-

6. Radio Link Deletion



UE CN


122/149


123/149

3 Service Request

3.3 IMSI Attachment & Location Update


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2 125

HLRSGSNMSC/VLR

MSC/VLR SGSN

Iub

RNCThe UE has selected a cell.

It had to declared its identity and its

location (LA & RA) to the Core Network.

So, it requests a RRC connection to send to

the Core Network information about its

situation.

The parameters are mainly the LA, the RAand its IMSI

Initial Attachment

3.3 IMSI Attachment & Location Update3.3.1 Principles


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2 126

When camping on a cell, the terminal must register its LA and/or its RA.

When the terminal moves across the network, it must update its LA (RA) which is stored in VLR

(SGSN) in the Core Network.

LA (RA) Update is performed periodically or when entering a new LA (RA).

HLRSGSNMSC/VLR

Location Area

(LA)Routing Area (RA)MSC/VLR SGSN

3.3 IMSI Attachment & Location Update3.3.2 Procedure: Direct Transfer


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RANAP RANAP1. Direct Transfer

CN Domain Indicator,NAS PDU

RRC RRC

2. Downlink Direct Transfer

(DCCH:FACH or DCH)

NAS message

UE Node-B SRNC CN

Use mainly for the IMSI attachment, location update and the authentification between the UE and

the Core Network

RANAP RANAP2. Direct Transfer

CN Domain Indicator,NAS PDU

RRC RRC

1. Uplink Direct Transfer

(DCCH:RACH or DCH)

CN node indicator, NAS message

3 Service Request3.4 Paging


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Core Network

Called number

HLRMSC/VLR MSC/VLR

Location Area

Some one is calling

me, I request a RRC

connection

Principle

Paging messagewith the IMSI of the

called UE

Iub

RNC

Iub

RNC

Iub

RNC

3.4 Paging3.4.1 Procedure 1: UE in Connected Mode


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RANAP RANAP1. Paging

CN Domain Indicator, UEidentity, Paging cause

RRC RRC2. Paging Type 2 (DCCH:FACH or DCH)

In this case the UE is already connected and is using a service (voice call, web-browsing ).

The Core Network knows the situation of the UE and mainly its Serving RNC. The CN

contacts directly the Serving RNC.

The RNC doesnt use the PCCH and the PCH but the channel used for the UE, dedicated or

common, according to the status of the UE.

UE Node-B SRNC CN

3.4 Paging3.4.2 Procedure 2: UE in Idle Mode


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RRC RRC2. Paging Type 1 (PCCH:PCH)

RRC RRC2. Paging Type1 (PCCH:PCH)


CN Domain Indicator, UEidentity, Paging cause


Idem

When the is in idle mode, UTRAN doesnt know where it is located and the Core Network

knows its location at the LA or RA level. UTRAN uses the PCCH and the PCH radio channels.

UE 1 Node-B1UE 2 Node-B2 RNC1 RNC2 CN

3.4 Paging3.4.3 Paging: PICH & PCH Radio Channels


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The UE doesnt watch the S-CCPCH.

It watches the PICH (Page Indicator

Channel) at regular and defined

interval and look for its PI, for

Paging Indicator.

The PI is based on the IMSI. Several

UEs can have the same PI.

When the UE find its PI on the

PICH, it watches the S-CCPCH to

check if it is for it and what is the

cause.

Then it requests on RRC connection

to have a RAB.

Transport Ch

Iub

RNC

PICHS-CCPCH

PCH

PCCH Logical Ch

Physical Ch

MAC

Physical

layer

In RNC

In Node B

PICHS-CCPCH

Paging

message

PI

PI

PI

...


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4 RAB Establishment

4 RAB Establishment4.1 Admission Control


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According to the previous part WCDMA in UMTS, if the interference level at the Node B level is

too high, the Node B cant decode all the signal. The size of the cell decreases. The interferences

are due to several causes:

The radio environment and the load of the adjacent cells,

Some users use too much power, the power control manages this problem,

There are too many users on the the cells

UTRAN has to check if there is enough UL radio resource

Iub

RNC

f

P

ISCP = NoSIR

PG

Eb

RSCP = Ec


SIR too small to

retrieve the message

2 others questions before adding a new user : Is there sufficient DL radio resource and

sufficient processing resources ?

4 RAB Establishment4.1 Admission Control [cont.]


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Is there sufficient UL Radio Resource -> Rx RAC

2 3jk10656aa Wcdma for Umts Aircel

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