Ee8315 Lecture8 Umts 2005 Pa1

8/8/2019 Ee8315 Lecture8 Umts 2005 Pa1

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UMTS

2005 H. Hmimy Lecture 9, Slide 1SMU EETS 8315 Advanced Topics in Wireless Communications - Spring05

Southern Methodist University

EETS 8315 / TC752-N

Advanced Topics in Wireless Communications

Spring 2005

http://www.seas.smu.edu/eets/8315

Lecture 8: UMTS: system and network

Instructor: Dr. Hossam Hmimy, Ericsson Inc.

[email protected](972) 583-0155

UMTS

2005 H. Hmim Lecture 9 Slide 2SMU EETS 8315 Advanced To ics in Wireless Communications - S rin 05

Announcement

Graduating Students please send me email

confirming that you are graduating this semester.


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UMTS


outline

UMTS History

UMTS spectrum

UMTS reference model and protocol stack UTRAN

Protocols and interfaces

components

Air interface (WCDMA)

Logical, transport and physical channels

...

UMTS


UMTS : History

Research Programs in Europe

RACE (Research in Advanced Communications Equipment)

Air interface

1988-1995

ACTS (Advanced Communications Technology and

Services)

1995-.

FRAMES (Future Radio Multiple Access Systems)

W-CDMA FDD

TDMA with and without spreading


3/31

UMTS


UMTS : WCDMA

Chip rate 3.84Mcps

Modulation QPSK

BW 5MHz

Frame length 10msec

Multiple access WCDMA/FDD, TD-CDMA/TDD

15 TS per frame

UMTS


UMTS Spectrum

In The US (?)

1700MHz / 2.2GHz

700MHz

1900MHz

W-CDMA

TDD

W-CDMA UL

FDD

W-CDMA

TDD

W-CDMA DL

FDD

MS MS

1900MHz

20 60 15 6030 3085

2200MHz


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UMTS


UMTS 3GPP

3GPP 99 introduction of UTRAN with separate CS & PS domains

no change in GPRS CN ( protocol stack)

New RAN

3GPP R4 (2001) Minor changes

3GPP R5 (2002) introduce GERAN. Traffic mainly PS,

change in CN ( Server and Media GW ) + IMS

signaling use IP based SIP session initiation protocol RFC 2543

HSDPA

3GPP R6 (2004) HSDPA UL Enhancement

Multimdia Broadcast Multicast Service (MBMS)

Super 3G

UMTS


UMTS Architecture

UTRAN UMTS Terrestrial Radio Access NetworkCN Core Network

UE User Equipment

CN

UTRAN

UE

Uu

Iu

CN : Enhanced GSM/GPRS CN

RN: UTRAN


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UMTS


UMTS reference model: R99

CSCF: responsible for call state control functions, serviceswitching function, address translation, vocoder negotiation

to support VoIP

3GSGSN 3GGGSN PSTN

GW

Roaming

GWHLR

CSCF

RAN

Applicationservices

2G network

IP

PSTNIu3G MSC

UMTS


UMTS Protocol Stack, user

Phy.

MAC

RLC

Phy.

IP

UDP

GTP-U

IP

Phy

L2

IP

Iu

SGSN GGSN

MS

IP

Phy.

MAC

RLC

PDCP

Phy.

L2

IP

UDP

GTP-U

IP relay

Phy.

ATM

AAL5/2

IP

UDP

GTP-U

L2

Phy.

ATM

AAL5/2

IP

UDP

GTP-U

IP relay

Node B + RNC

UTRAN

PDCP


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UMTS


UMTS Protocol Stack, control

Phy.

MAC

RLC

Iu

SGSN GGSNMS

Phy.

MAC

RLC

Phy.

ATM

AAL5/2

SCCP

Node B + RNC

UTRAN

RRC

Phy.

ATM

AAL5/2

SCCP

Phy.

ATM

AAL5/2

SCCP

Phy.

ATM

AAL5/2

SCCP

Phy.

ATM

AAL5/2

SCCP

Signaling connection control part

UMTS


UMTS CN

R99

R5

See section 5.7 of the textbook pp 95-97.


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UMTS


UTRAN Architecture

UTRAN consists of

RNCs (similar to BSCs)

Node Bs (similar to BTSs)

RNS

RNC

RNS

RNC

Core Network

Node B Node B Node B Node B

Iu Iu

Iur

Iub IubIub Iub

UMTS


Functions of UTRAN Components

RNC

Serving RNC (SRNC)

L2 functionality

Terminates RR control signaling and RANAP)

Uplink/downlink signal transfer, mobility, soft handoff, outerloop/ downlink power control,

Controlling RNC (CRNC)

Load and congestion control, admission and code allocation

Drift RNC (DRNC)

No L2 functionality.

Combining diversity

Routes the traffics from Iub to Iur transparently.


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UMTS


Functions of UTRAN Components

Node B:

logical node, maintains link with UE

responsible for radio transmission for one or more cells,

adds/removes radio links on demand, mapping logical resources to physical resources,

inner loop power control,

interconnecting UE from different manufacturers.

UMTS


Protocol Model for UTRAN Interfaces

UTRAN consists of

Radio Network Layer (specific to UTRAN itself)

Transport Network Layer (standard technology: ATM)

The UTRAN specific protocols include Radio Access Network Application Part: Radio Network Signalling

over the Iu.

Radio Network Subsystem Application Part: Radio Network

Signalling over the Iur.

Iub interface uses node B application protocol (NBAP).


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UMTS


UTRAN Interfaces

Iur Interface (RNC RNC)

point-to-point open interface,

macro-diversity support,

transport signalling for mobility and radio resource allocation.

Iub Interface (RNC Node B)

interconnection of equipment from different manufacturers,

allows Abis (GSM/GPRS transmission sharing),

transports DCH, RACH, FACH and DSCH data,

enables negotiation of radio resources between node B and

RNC

RNC

RNC

Node

B

Node

B

Node

B

Iur

Iub

Iu

UMTS



Signaling applications

NBAP

RNSAP

RANAP

Phy.

ATM

AAL5MTP3-B

SCCP

RANAP

Phy.

ATM

AAL5

MTP3

SCCP

RNSAP

Iu

Iur

SSCOPSCCF-NNI

Phy.

ATM

AAL5

NBAP

SSCOP

SCCF-NNI

IubSSCOP:Service specific Connection oriented protocolSSCF: service specific Convergence function

NNI: net to net interface


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UMTS



User Data (traffic)

Phy.

ATM

AAL2/5

IP

UDP

IP data

Phy.

ATM

AAL2/5

Iur Data

IuIur

Phy.

ATM

AAL2

Iub

Logical ch.

data

GTP-U

UMTS


Physical Layer

Physical layers consists of

physical channel

transport channel

Physical layer provides Encoding / decoding of transport channels

multiplexing/de-multiplexing of transport channels

mapping transport channels onto physical channels

RF Processing (modulation/demodulation, spreading/de-

spreading)

Closed loop power control

Macro-diversity Distribution/Combining


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UMTS


WCDMA Features

Soft Handoff

communicate with multiple base stations

Multipath Receptionrake receivers provide diversity gain

Fast Power Control

combats near-far problem

Frequency Reuse of 1

simplifies frequency planning

Soft Capacity

flexible coverage and capacity palnning

UMTS


Despreading

User

data

Code

Chip

sequence

0 1

1 1 0 0 1 1 0 0

+1

0

-1

+1

0

-1

+1

0

-1

Spreading1 1 0 0 1 1 0 0

+1

0

-1

+1

0

-1

+1

0

-1

Case 1

1 0 1 0 1 0 1 0

+1

0

-1

+1

0

-1

+1

0-1

Case 2


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UMTS


BS 1 BS 2

Fully loaded system

Unloaded system

Cell breathing

UMTS


Multipath Propagation

10

2

3

Time Dispersion

10 2 3

Radio Environment


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UMTS


C

O

M

B

I

N

E

R Power measurements

of neighbouring BS

Sum of individual

multipath components

Finger #1

Finger #2

Finger #3

Searcher Finger

Finger #N

Buffer/delay

CorrelatorsChannel

The RAKE-receiver principle

UMTS


Power Control

What?

The Transmitter adapts the output power according to Path

Loss

Why? Mainly to solve the Near-Far problem

Goal is that all users should experience the same SIR

No PC on pilot or some CCCH


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UMTS


Power Control ..

Open Loop Power control (Initially, No signaling)

UL

UE measure pilot,

read Interference level from BCH,

TX at calculated power,

Ramp up power

DL

BS calculate required power,

Tx at calculated power,

Ramp up Power

UMTS


Power Control ..

Inner Loop Power control UL/DL (fast)

For a fixed SIR target per service (RAB), UE or Node-B will

use:

Signaling channel, TCP, continuously @ rate 1500 times/s,

To relatively changes (up or down) the power to reach the

SIR target.

Outer loop Power control (Slow)

If the BLER measured (DL @ UE, UL@RNC) is below/

above the target,

UE/RNC increase/reduce SIR target.

Use the new target for the Inner loop PC.


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UMTS


Handover

Inter-Radio Access Technology (IRAT) Handover

Traffic and Control Channels are Disconnected and must be

Reconnected

Inter-frequency Handover Traffic and Control Channels are Disconnected and must be

Reconnected

Soft Handover

Unique to CDMA

During Handover, the MS has traffic connections with two BSs

Softer Handover

between two sectors of the same site, with identical timing

UMTS


Soft Handover Add/Drop/Replace

Thresholds

Soft Handover Measurement and Decision

Cell 1Connected

Add Cell 2Replace Cell 1

with Cell 3

time

Drop Cell 3

EC/ N0

Cell 1

Cell 2

Cell 3

T_ADD

T_REPLACE

t t t

T_DROP


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UMTS


Channelization and scrambling codes

Channelization code

UL: separation of data

(DPDCH) and control(DPCCH) in same UE

DL separation of DLconnection of differentusers

UL 4-256 chips, DL 4-512chips

# of codes under one SC=SF

OVSF Responsible for spreading

Scrambling codes SC

UL separation of Users

DL separation of sectors

UL 38400 or 256 chips, DL

38400 chips

UL Millions, DL 512

Long gold code

Does not do spreading.

UMTS


Unusable code

Channelization Code tree

Adapts user bit-rate to code length (figure 4-11)

C2.1 = {1 1}

C4.2 = {1 1-1-1}

C8.3 = {11-1-111-1-1}

C8.4 = {11-1-1-1-111}

SF = 2 SF = 4 SF = 8

Unusable codesC2.1 = {1 1}C4.1 = {1111}

UsingC4.1 C8.1 = {11111111}

C8.2 = {1111-1-1-1-1}

UsingC8.4


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UMTS


Complex SC

Complex SC (Downlink)

I

Q

SC-Q

SC-I

FIR

Filter

FIR

Filter

cos ( 2fRFt)

sin ( 2fRFt)

SC-I

RFOutput

( )QIS

QIS

SCISCQQ

SCQSCII

+=

=

Is

Qs

3GPP TS 25.212 53GPP TS 25.212 5

UMTS


WCDMA Code Types

Synchronization Codes

Primary Sync. Code: Fixed 256-bit code

Unmodulated fixed for all cells

Helps UE identify the presence of a WCDMA BS

Helps UE achieve Slot Synchronization Secondary Sync. Codes: 256-bit codes

Unmodulated different for different cells ( group 64)

Helps UE achieve Frame and slot Synchronization

Pilot Codes

Common (CPICH) provides coherent reference for UE

receiver

Pilot bits embedded into each time slot of the DCH


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UMTS


WCDMA Channels

Logical

Transport

Characterize how data is transmitted

Provide services to the upper layer

Mapped to physical channels

Common transport channel

Dedicated transport channels

Physical

Carry one or more transport channels

Responsible for transporting data over the air.

Identified by carrier frequency, orthogonal code, relative phase

A super frame consists of 72 radio frames.

One radio frame is

10 milliseconds in duration

divided into 15 time slots

each slot has a duration of 0.625 milliseconds

UMTS


Downlink Logical Channels Common Downlink Logical Channels

BCCH (Broadcast Control Channel)

Broadcasts cell site and system identification to all UE

PCCH (Paging Control Channel)

Transmits paging information to a UE when the UEs location is

unknown CCCH (Common Control Channel)

Transmits control information to a UE when there is no RRCConnection

CTCH (Common Traffic Channel)

Traffic channel for sending traffic to a group of UEs.

Dedicated Downlink Logical Channels

DCCH (Dedicated Control Channel)

Transmits control information to a UE when there is a RRCConnection

DTCH (Dedicated Traffic Channel)

Traffic channel dedicated to one UE

3GPP TS 25.301 5.3.1.13GPP TS 25.301 5.3.1.1


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UMTS


Uplink Logical Channels Common Uplink Logical Channels

CCCH (Common Control Channel)

Transmits control information to a UE when there is no RRC Connection

CTCH (Common Traffic Channel)

Traffic channel for sending traffic to a group of UEs.

Dedicated Uplink Logical Channels

DCCH (Dedicated Control Channel)

Transmits control information from a UE when there is a RRC Connection

DTCH (Dedicated Traffic Channel)

Traffic channel dedicated from one UE

3GPP TS 25.301 5.3.1.13GPP TS 25.301 5.3.1.1

UMTS


Downlink Transport Channels

Common Downlink Transport Channels BCH (Broadcast Channel)

Continuous transmission of system and cell information

PCH (Paging Channel)

Carries control information to UE when location is unknown

Pending activity indicated by the PICH (paging indication channel)

FACH (Forward Access Channel)

Used for transmission of idle-mode control information to a UE

No closed-loop power control

DSCH (Downlink Shared Channel)

Carries dedicated control and/or traffic data; shared by several UEs

Dedicated Downlink Transport Channels

DCH (Dedicated Channel) Carries dedicated traffic and control data to one UE

3GPP TS 25.301 5.2.1.13GPP TS 25.301 5.2.1.1


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UMTS


Uplink Transport Channels

Uplink Transport Channels

Common Uplink Transport Channels

RACH Random Access Channel

Carries access requests, control information, short data Uses only open-loop power control

Subject to random access collisions

CPCH Uplink Common Packet Channel

Carries connectionless packet data to PCPH

Dedicated Uplink Transport Channels

DCH Dedicated Channel

Carries dedicated traffic and control data from one UE

UMTS


Physical channels

PCCPCH

Fixed rate of 32 kpbs and SF=256

Transmitted continuously over an entire cell

No transmission during the 1st 256 chips within every slot of

radio frames

Secondary CCPCH

Variable rate

Discontinuous transmission

Supports narrow transmission with in a cell based on

configuration and use.

DPDCH ( Dedicated Phys. Data Channel)

DPCCH ( Dedicated Phys. Control channel)

CPICH (common pilot)


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UMTS


WCDMA Downlink Physical Channels

Common Downlink Physical Channels P-CCPCH Common Control Physical Channel (Primary)

Broadcasts cell site information

Broadcasts cell SFN; Timing reference for all DL

32kbps SF 256 continues transmission

SCH Synchronization Channel Fast Synch. P frame, S slot, time-multiplexed with P-CCPCH

S-CCPCH Common Control Physical Channel (Secondary)

Transmits idle-mode signaling and control information to UEs

Variable rate, with DTX

P-CPICH Common Pilot Channel

S-CPICH Secondary Common Pilot Channel (for sectored cells)

PDSCH Physical Downlink Shared Channel

Transmits high-speed data to multiple users

Dedicated Downlink Physical Channels DPDCH Dedicated Downlink Physical Data Channel

DPCCH Dedicated Downlink Physical Control Channel

Transmits connection-mode signaling and control to UEs

3GPP TS 25.2113GPP TS 25.211

UMTS


WCDMA Downlink Physical Channels

Downlink Indicator Channels

AICH (Acquisition Indicator Channel)

Acknowledges that BS has acquired a UE Random Access attempt

(Echoes the UEs Random Access signature)

PICH (Page Indicator Channel)

Informs a UE to monitor the next paging frame

AP-AICH (Access Preamble Indicator Channel

Acknowledges that BS has acquired a UE Packet Access attempt

(Echoes the UEs Packet Access signature)

CD/CA-ICH

Confirms that there is no ambiguity between UE in a Packet Access

attempt

(Echoes the UEs Packet Access Collision Detection signature)

Optionally provides available Packet channel assignments

CSICH

Broadcasts status information regarding packet channel availability

3GPP TS 25.2113GPP TS 25.211


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UMTS


WCDMA Uplink Physical Channels

Common Uplink Physical Channels

PRACH Physical Random Access Channel

Used by UE to initiate access to BS

PCPCH Physical Common Packet Channel

Used by UE to send connectionless packet data

Dedicated Uplink Physical Channels

DPDCH Dedicated Uplink Physical Data Channel

DPCCH Dedicated Uplink Physical Control Channel

Transmits connection-mode signaling and control to BS

3GPP TS 25.2113GPP TS 25.211

UMTS


Common Pilot Channel

Downlink CPICH (Common Pilot Channel) (C256,0)

Pilot Symbol Data (10 symbols per slot)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

1 Frame = 15 slots = 10 mSec

1 timeslot = 2560 Chips = 10 symbols = 20 bits = 666.667 uSec

A A A A A A A A A A A A A A A A A A A A A AA A A

-A A A -A A -A -A A A -A -A A A -A -A A A -A -A A A -AA A -A

Slot 0 Slot 1Slot 14

Antenna 1Symbols

Antenna 2Symbols

If transmit diversity is used, then the pilot symbols are as shown for each antenna:

3GPP TS 25.211 5.3.33GPP TS 25.211 5.3.3


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UMTS


Sync Channel /

Primary Common Control Channel Downlink SCH / P-CCPCH (C256,1 )

Broadcast Data (18 bits)SSCi

BCH Spreading Factor = 2561 Slot = 0.666 mSec = 18 BCH data bits / slot

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15


2304 Chips256 Chips

SCH BCH

3GPP TS 25.211 5.3.3.23GPP TS 25.211 5.3.3.2

PSC

UMTS


Secondary Common Control Channel

Downlink S-CCPCH

Spreading Factor = 256 to 41 Slot = 0.666 mSec = 2560 chips = 20 * 2k data bits; k = [0..6]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15


20 to 1256 bits0, 2, or 8 bits

3GPP TS 25.211 5.3.3.23GPP TS 25.211 5.3.3.2

DataTFCI or DTX Pilot

0, 8, or 16 bits


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UMTS


Dedicated Control/Data Channel

Downlink DPCCH/DPDCH Frame

Data 2TFCIData 1 TPC

1 Slot = 0.666 mSec = 2560 chips = 10 x 2^k bits, k = [0...7]SF = 512/2k = [512, 256, 128, 64, 32, 16, 8, 4]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15


DPDCH

Pilot

DPDCH DPCCH DPCCH

The DPDCH carries user traffic, layer 2 overhead bits, and layer 3 signaling data.

The DPCCH carries layer 1 control bits: Pilot, TPC, and TFCI

Downlink Closed-Loop Power Control steps of 1 dB, 0.5 dB

The DPDCH carries user traffic, layer 2 overhead bits, and layer 3 signaling data.

The DPCCH carries layer 1 control bits: Pilot, TPC, and TFCI

Downlink Closed-Loop Power Control steps of 1 dB, 0.5 dB

3GPP TS 25.211 5.3.23GPP TS 25.211 5.3.2

UMTS


Uplink DPDCH/DPCCH

Uplink DPDCH/DPCCH

Coded Data, 10 x 2^k bits, k=06 (10 to 640 bits)

Dedicated Physical Data Channel (DPDCH) Slot (0.666 mSec)

Pilot FBI TPC

Dedicated Physical Control Channel (DPCCH) Slot (0.666 mSec)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15


I

QTFCI

DPCCH: 15 kb/sec data rate, 10 total bits per DPCCH slot

PILOT: Fixed patterns (3, 4, 5, 6, 7, or 8 bits per DPCCH slot)

TFCI: Transmit Format Combination Indicator (0, 2, 3, or 4 bits)

FBI: Feedback Information (0, 1, or 2 bits)

TPC: Transmit Power Control bits (1 or 2 bits); power adjustment in steps of 1, 2, or 3 dB

3GPP TS 25.211 5.2.13GPP TS 25.211 5.2.1


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UMTS


Downlink Data Coding, Multiplexing

Conv. Coding R=1/3

304

304

#2 344

688

688

#1 344

420

344 76

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

Traffic data (122x2)per 20ms

Add CRC bits

Add Tail bits

2nd interleaving 420 420 420

344 76 344 76 344 76

#1 76 #2 76 #3 76 #4 76

804

260

244Tail 8

CRC16

360

112

Tail 896

96CRC 16

Rate matching

1st interleaving

Add CRC bits

Layer 3 Control data per 40ms

Add Tail bits

Conv. Coding R=1/3

#2 344#1 344Radio Frame

Segmentation

slot segmentation

30 ksps DPCH

Rate matching

1st interleaving

244

Traffic @ 12.2 kbpsTraffic @ 12.2 kbps L3 Data @ 2.4 kbpsL3 Data @ 2.4 kbps3GPP TS 25.101 App. A.3

3GPP TS 25.101 App. A.3

28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28 28

MUX: Pilot, TPC, TFCI 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12

600 bits (300 symbols) 600 bits (300 symbols) 600 bits (300 symbols) 600 bits (300 symbols)

Data from second 244-bit packet

UMTS


Uplink Data Coding, Multiplexing

Turbo Coding R=1/3

360

9525

23160

11580

9600

9525 75

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

Traffic data (3840x2)

2nd interleaving 9600 9600 9600

9525 75 9525 75 9525 75

75 75 75 75

11568

7712

3840

Termination

bits

CRC16

360

112

Tail 896

96

CRC 16

Rate matching

1st interleaving

Layer 3 Control data

Conv. Coding R=1/3

Frame Segmentation

slot segmentation

480 ksps DPDCH

1st interleaving

3840

Traffic @ 384 kbpsTraffic @ 384 kbps L3 Data @ 2.4 kbpsL3 Data @ 2.4 kbps3GPP TS 25.101 App. A.3

3GPP TS 25.101 App. A.3

9600 bits (9600 symb.) 9600 bits (9600 symb.) 9600 bits (9600 symb.) 9600 bits (9600 symb. )

3840

CRC16

3840

Concatenate Concatenate

Add CRC bits Add CRC bits

12 11568 12

Data from second 3840-bit packet

640 640 640 640 640 640 640 640 640 640 640 640

11580

9525 9525 9525

Frame Segmentation 90 90 90 90


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UMTS


Mapping DL Channels

BCCH CTCHPCCH CCCH DTCHDCCH Logical

BCH FACHPCH DCH DSCH transport

P-CCPCH DPDCHS-CCPCH DPCCH PDSCH Physical

UMTS


Mapping UL Channels

CCCH DTCH DCCH Logical

RACH DCH DSCH transport

DPDCH DPCCH PCPCH PhysicalPRACH


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UMTS


Acquisition

On Power-up, the mobile attempts to find a

channel.

Node B send s exactly the same 256 chip code in

same slot (Primary SCH)

Mobile achieves slot level synchronization

After that, Mobile looks for the 10 msec frame.

Now Secondary SCH is searched.

There are 512 possible cell specific scrambling

codes divided in to 32 groups.

Mobile tries 16 possible codes in parallel.

UMTS


Downlink spreading and modulation

cch: Channelization codes (OVSF code, 4-256 chips)

cscramb: Downlink scrambling code (Gold code, 40960 chips)

p(t)

IQ

MuxDPDCH/DPCCH

cos(t)

p(t)

sin(t)cch cscramb

16*2K kbps 3.86 Mcps

OVSF codes ensure DL orthogonality even with different rates and

spreading factors for different users

DPCCH - dedicated packet control channel DPDCH - dedicated packet data channel


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UMTS


Uplink Spreading and Modulation

cDPDCH

p(t)

IQ

Mux

I

I+jQ

Re { }

Q

DPDCH

DPCCH Im { }

cos(t)

p(t)

sin(t)

cscramb cscramb(optional)

cDPCCH

cDPDCH, cDPCCH: Channelization codes (OVSF codes, 4-256 chips)

cscramb: Primary scrambling code (VL Kasami code, 256 chips)

cscramb: Secondary scrambling code (Gold code, optional, 40960 chips)

16*2K kbps 3.86 Mcps

Additional DPDCHs may be added to either I or Q (multi-code transmission)

DPCCH - dedicated packet control channel DPDCH - dedicated packet data channel

UMTS


MODULATION

UTRA uses a base spreading rate of 3.84 Mcps in

5 MHz bandwidth

Variable data rates are provided

QPSK Modulation (I and Q components) Reverse-link Mapping DPDCH -> I and DPCCH ->

Q.

Forward-link: DPDCH & DPCCH are time

multiplexed into I & Q components.


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UMTS


FDD vs. TDD

FDD Option allows continuous transmission in

both directions requires a paired frequency band

suited for symmetric bandwidth needs

TDD Option same carrier frequency is utilized for

uplink/downlink transmission (using time

division) works with unpaired frequency band

suited for asymmetric applications

easier to obtain spectrum

UMTS


TDD Frame Structure

4.096

Mchi /s

time

frequency

625 s

10 ms

Figure 1: The TDD frame structure

10 ms

Single-switching-point configuration (symmetric DL/UL allocation)

10 ms

Single-switching-point configuration (asymmetric DL/UL allocation)

Figure 2: TDD frame structure examples


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UMTS


References

UMTS Networks by H. Kaaranen et al 2001 chapter 4, 5, 9

http://www.ericsson.com/review/1999_03/files/1999031.pdf

S. Nanda, et al, Adaptation techniques in wireless packet data servicesIEEE communications magazine, January 2000.

M. Zeng, et al, Harmonization of global third generation Mobile systems,

IEEE communications magazine, December 2000.

UMTS

Reading assignment

Chapter 5, 6 , 7

Ee8315 Lecture8 Umts 2005 Pa1

Documents

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