Wcdma Umts-call Flow

8/13/2019 Wcdma Umts-call Flow

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UMTS - Call Life Cycle

Stas Shilkrut

July 2008

This Presentation based on

3G TR 25.922 version 2.0.0 paper


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Outline

WCDMA / UMTS basic WCDMA vs. CDMA2000

Air Interface (WCDMA)

3G Traffic Class QoS

Protocol Architecture

Network Architecture

Radio Resources Management Admission Control, Load Control, Packet Scheduler

Handover Control and Power Control

Call flow R99-call flow details

Reviewing UE Logs of various call services


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WCDMA vs. CDMA2000

Some of the

Major Differences

WCDMA CDMA 2000 Remarks

Spread Spectrum

Technique

5Mhz Wideband

DS-SS

Multicarrier,

3x1.25MHz

Narrowband DS-SS,

250kHz Guard Band

Multicarrier does not requires a contiguous

spectral band.

Both scheme can achieve similar

performance

Chip Rates 3.84Mcps 3.6864Mcps (1.2288

per carrier)

Chip Rate alone does not determine system

capacity

Frame Lengths 10ms 20ms for data, 5ms for

control,26ms for Sync

Response and efficiency tradeoff

Fast Power Control

Rate

1.5kHz 800Hz Higher gives better link performance

Base Station

Synchronization

Asynchronous Synchronized Asynchronous requires not timing reference

which is usually hard to acquire.

Synchronized operation usually gives better

performance


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Multiple Access Method DS-CDMA

Duplexing Method FDD/TDD

Base Station Synchronization Asynchronous Operation

Channel Separation 5MHz

Chip Rate 3.84 Mcps

Frame Length 10 ms

Service Multiplexing Multiple Services with different QoS

Requirements Multiplexed on one Connection

Multirate Concept Variable Spreading Factor and Multicode

Detection Coherent, using Pilot Symbols or Common Pilot

Multi-user Detection, Smart Antennas Supported by Standard, Optional in

Implementation

WCDMA Air Interface, Main Parameters


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DSSS - is a modulationtechnique. As with other spread spectrumtechnologies, the transmitted signaltakes up morebandwidththan the information signal that is being modulated. The name 'spread

spectrum' comes from the fact that the carrier signals occur over the full bandwidth (spectrum) ofa device's transmitting frequency.

The information signal is inherently narrowband, on the order of less than 10 KHz. The energy fromthis narrowband signal is spread over a much larger bandwidth by multiplying the informationsignal by a wideband spreading code. Direct sequence spread spectrum is the technique used inCDMA systems.

Frequency Hopped Spread Spectrum

Spreading can also be achieved by hopping the narrowband information signal over a set of

frequencies. This type of spreading can be classified as Fast or Slow depending on the rate of hoppingto the rate of information:

Fast hoppingthe hopping rate is larger than the bit rate.

Slow hoppingmore than one bit is hopped from one frequency to another.

Direct-sequence spread spectrum
http://en.wikipedia.org/wiki/Modulationhttp://en.wikipedia.org/wiki/Spread_spectrumhttp://en.wikipedia.org/wiki/Bandwidth_%28signal_processing%29http://en.wikipedia.org/wiki/Bandwidth_%28signal_processing%29http://en.wikipedia.org/wiki/Spread_spectrumhttp://en.wikipedia.org/wiki/Modulation


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UMTS FDD/TDD - radio transmission modes

UMTS FDD (Frequency Division Duplex)

190 MHz duplex distance

ca. 5MHz (variable) carrier spacing (DS CDMA Direct Sequence CDMA)

12 bands in uplink & downlink

UMTS TDD (Time Division Duplex)

5 carriers in total, 15 timeslots per frame

a user may use one or several timeslots

a timeslot can be assigned to either uplink or downlink


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UMTS Frame Structure

TPC: Transmit Power Control

FBI:Feedback Information

TFCI :Transport Format Combination Indicator

TFI: Transport Format Identifier

DPCCH: Dedicated Physical Control Channel

DPDCH: Dedicated Physical Data Channel

DPCH: Dedicated Physical Channel


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UMTS TDD Frame Structure

frame

W-TDMA/CDMA

2560 chips per slot

symmetric or asymmetric

slot assignment to up/downlink

tight synchronization needed

0 1 2 13 14 15...

data midample data

slot

625 s

10 ms

traffic burstGP

GP: Guard Period

1 radio frame (10 ms), 15*2560 chips (3.84 Mcps)

Slot iSlot 1 Slot 2 Slot 15time

In each time slot the contribution of each user, a so-called burst, is a combination of two data fields ,a

midamble and a guard period as shown in Fig. The midamble is a training sequence used particularly

for channel equalization. In terms of spectrum efficiency, this training sequence is considered as a

wasted data, which could represent up to 20% of the whole UMTS TDD physical channel


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UMTS Traffic Classes

Conversational real time traffic flows, greatest delay

sensitivity, e.g. voice or video telephony.

Streaming - real time traffic flows, medium delaysensitivity, e.g. one-way streaming media.

I nteractive - used for interactive but delay tolerant trafficflows which require smaller data error rates, e.g. webbrowsing or chat.

Background used for non-urgent, delay tolerant trafficflows that require smaller data error rates, e.g. large filedownload or email retrieval.


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3G Traffic Class QoS Requirements

Conversational

RT

Streaming

RT

Interactive

NRT

Background

NRT

Applications Audio/video

conference

Audio/video

streaming

Web browsing,

network games

File download,

emails

Reliability

control Guaranteed

no ARQ

Dynamic

unACK ARQ

Dynamic ACK

ARQ

Dynamic ACK

ARQ

Delay 100, 200, 400msec


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Standardization of WCDMA / UMTS

3GPP Release 4

3GPP Release 5-6All IP Vision

Source : Overview of UMTS, Guoyou He, Telecommunication Software and Multimedia Laboratory, Helsinki University of Technology


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HSDPA

High Speed Downlink Packet Access

Standardized in 3GPP Release 5

Improves System Capacity and User Data Rates in the Downlink Direction to 10Mbpsin a 5MHz Channel

Adaptive Modulation and Coding (AMC) Replaces Fast Power Control :

User farer from Base Station utilizes a coding and modulation that requires lower Bit Energyto Interference Ratio, leading to a lower throughput

Replaces Variable Spreading Factor :Use of more robust coding and fast Hybrid Automatic Repeat Request (HARQ, retransmitoccurs only between UE and BS)

HARQprovides Fast Retransmission with Soft Combining and IncrementalRedundancy Soft Combining : Identical Retransmissions

Incremental Redundancy : Retransmits Parity Bits only

Fast Scheduling Function which is Controlled in the Base Station rather than by the RNC


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P.S - UMTS Protocol Architecture

Node B

UE

Applic.

PDCP

PHY

IuUu

GTP-U

UDP

AAL5/ATM

IP

RNCIP

TCP GGSN

GTP-U

SGSN

IPIP routing

UDP/TCP

Gn/Gp

IPIP

IP

TCP

IPserver

IP

Gi

GTP-U

UDP

AAL5/ATM

IP

GTP-U

UDP/TCP

IP

GPRS

IP backbone

Gn

Application

RLC

MAC

Iu UP Iu UP

IP

PDCP

RLC

MAC

Iub

PHYAAL2/ATM

PHY

AAL2/ATM

FPFP

Radio Bearers

Logical channels

Transport channels

UTRAN Packet Switched Core Network

Physical channels

Radio Access Bearers

PDCP - Packet Data Convergence Protocol is used in UMTS to format the data into a suitable

structure prior to transfer over the air interface.

RLC - Radio Link Control A sub layer of the radio interface that provides reliability. RLC varies

depending on the communication system employed.


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Summary of Protocols (CS user plane)

RNCNode BUE MSC

WCDMAL1

RLC

MAC

PDH/SDH

ATM

AAL2

FP

Iub IuUu

RLC

MAC

PDH/SDH

ATM

AAL2

FP

WCDMAL1

CS

applicationandcoding

PDH/SDH

ATM

AAL2

Iu-UPprotocol

PDH/SDH

ATM

AAL2

CS

applicationand

coding

Iu-UPprotocol

FPFrame Protocol

AAL2 - ATM Adaptation layer 2 supports continuous bit rate transmissions, but also solves the problems ofpacketization delay and efficiency in the use of bandwidth resources.

ATM - Asynchronous Transfer Mode - network technology based on transferring data in cells or packets of a

fixed size. The small, constant cell size allows ATM equipment to transmit video, audio, and computer data over

the same network, and assure that no single type of data hogs the line. ATM creates a fixed channel, or route,

between two points whenever data transfer begins. This differs from TCP/IP , in which messages are divided into

packets and each packet can take a different route from source to destination. This difference makes it easier to

track and bill data usage across an ATM network, but it makes it less adaptable to sudden surges in networktraffic.


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Summary of Protocols (UE control plane)

PDH/SDH

ATM

AAL2

FP

RNCNode BUE CN

WCDMAL1

Iub IuUu

RRC

RLC

MAC

PDH/SDH

ATM

AAL2

FP

WCDMAL1

RRC

RLC

MAC

PDH/SDH

ATM

AAL5

SSCOP

RANAP

MTP3b

SCCP

PDH/SDH

ATM

AAL5

SSCF-NNI

RANAP

MTP3b

SCCP

SSCOP

SSCF-NNI

NAS NAS

Network Application Support

PDH - Plesiochronous Digital HierarchyThe (PDH) is a technology used in telecommunications networksto transport large quantities of data over

digital transport equipment such as fibre opticand microwave radiosystems. The term plesiochronousis

derived from Greek plesio, meaning near, and chronos, time, and refers to the fact that PDH networks run in

a state where different parts of the network are almost, but not quite perfectly, synchronised. Due to

limitations such as lack of flexibility and performance it has been superseded in some areas by SDH

(Synchronous Digital Hierarchy).
http://bword//!!ARV6FUJ2JP,telecommunications%20network/http://bword//!!ARV6FUJ2JP,fibre%20optic/http://bword//!!ARV6FUJ2JP,microwave%20radio/http://bword//!!ARV6FUJ2JP,plesiochronous/http://bword//!!ARV6FUJ2JP,synchronised/http://bword//!!ARV6FUJ2JP,synchronised/http://bword//!!ARV6FUJ2JP,plesiochronous/http://bword//!!ARV6FUJ2JP,microwave%20radio/http://bword//!!ARV6FUJ2JP,fibre%20optic/http://bword//!!ARV6FUJ2JP,telecommunications%20network/


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Radio Resources Management

Network Based Functions

Admission Control (AC) Handles all new incoming traffic. Check whether new connection can be admitted to the system and

generates parameters for it.

Load Control (LC) Manages situation when system load exceeds the threshold and some counter measures have to be taken to

get system back to a feasible load.

Packet Scheduler (PS) Handles all non real time traffic, (packet data users). It decides when a packet transmission is initiated and

the bit rate to be used.

Connection Based Functions

Handover Control (HC)

Handles and makes the handover decisions. Controls the active set of Base Stations of MS.

Power Control (PC) Maintains radio link quality.

Minimize and control the power used in radio interface, thus maximizing the call capacity.

Source : Lecture Notes of S-72 .238 Wideband CDMA systems, Communications Laboratory, Helsinki University of Technology


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Network Based Functions

RT / NRT : Real-time / Non-Real-time RAB : Radio Access Bearer

Source : Lecture Notes of S-72.238 Wideband CDMA systems, Communications Laboratory, Helsinki University of Technology

Only new RTPreventive

State


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Connection Based Function- Power Control

Power Control

Prevent Excessive Interference and Near-farEffect

Open-Loop Power Control

Rough estimation of path loss fromreceiving signal

Initial power setting, or when nofeedback channel is exist

Fast Close-Loop Power Control

Feedback loop with 1.5kHz cycle toadjust uplink / downlink power to its

minimum Even faster than the speed of Rayleigh

fading for moderate mobile speeds

Outer Loop Power Control

Adjust the target SIR setpoint in basestation according to the target BER

Commanded by RNC

Fast Power Control

If SIR < SIRTARGET,send power up

command to MS

Outer Loop Power Control

If quality < target, increases

SIRTARGET


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Connection Based Function- Handover

Hard Handover

Soft Handover Softer Handover

For UMTS the following types of handover are specified:

1.Handover 3G -3G (i.e. between UMTS and other 3G systems)

2.FDD soft/softer handover

3.FDD inter-frequency hard handover

4.FDD/TDD handover (change of cell)

5.TDD/FDD handover (change of cell)

6.TDD/TDD handover

7.Handover 3G - 2G (e.g. handover to GSM)

8.Handover 2G - 3G (e.g. handover from GSM)

Active Set

Monitored Set (Neighbor Set )Cells, which are not included in the active set, but areincluded in the CELL_INFO_LIST

Detected SetReporting of measurements of the detected set is only applicable to intra-frequency measurements made by UEs in CELL_DCHstate

Further reading:3GPP 25.331

Only UTRA FDD mode supports soft and softer handovers. Hard

and inter-system handovers are supported in both TDD and FDDmode.

Source - Study of soft handover in UMTS Stijn N. P. Van Cauwenberge


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Downlink code usage

-512 8192Scrambling CodesPrimary Code15Secondary Codes .8192/16=512

Channelization Codes.- .-SF=4256Spreading Factor


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UE Synchronization1.Slot synchronization

S-SCHFrame synchronizationUE. . UE -64

-Scrambling code identification Primary 512"scrambling codes -64 .8

Three UE Synch Stages1.Slot synchronization

2.Frame synchronization

3.Scrambling code identification

A S i i


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UTRAN SynchronizationDifferent UTRAN synchronization required in a 3G network:

Network synchronization

Node synchronization

Transport channel synchronization

Radio interface synchronization

Time alignment handling

Synchronization Issues Model


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Mapping of UE state to 3GPP Specifications

3rd Generation Partnership Project;

Technical Specification Group Radio Access Network;

Radio Resource Management Strategies

(3G TR 25.922 version 2.0.0)


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MT CallMO Call

RRCConnection

Establishment

Radio AccessBearer

Establishment

PagingUser PlaneData Flow

Overview of WCDMA Call SetupUE modes and RRC states

In both the Cell PCH and the URA PCH state

Nouplink activity is possible. The only

difference between both states is that in the Cell

PCH state the location is known on cell level

according to the last cell update made while in

the URA PCH state the location is known only

to UTRAN Registration Area (URA8) level

according to the last URA update made in the

Cell FACH state.


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I iti l ti t t k


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Initial connection to network


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Basic Mobile Originating

Call Diagram

Further reading:3GPP TS 25.303, 25.331

http://www.umtsworld.com/technology/moc.htm

RRC i bli h (DCH)


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RRC connection establishment (DCH)

1. RRC CONNECTION REQUEST

UE RNCNode B

2. AdmissionControl

4. Start RX

9. Start TX

3. RADIO LINK SETUP REQUEST

5. RADIO LINK SETUP RESPONSE

10. RRC CONNECTION SETUP

11. L1 SYNCH

13. RRC CONNECTION SETUP COMPLETE

RRC RRC

C-NBAP C-NBAP

C-NBAP C-NBAP

ALCAP ALCAP6. ESTABLISH REQUEST

ALCAP ALCAP7. ESTABLISH CONFIRM

RRC RRC

12. RL RESTORE INDICATIOND-NBAP D-NBAP

RRC RRC

8. UPLINK & DOWNLINK SYNCFPFP

Phase - 1

Access Link Control Application PartAAL2 signalling protocol

FPFrame Protocol


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Phase 2


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Phase - 3

ISDN User Part is part of the SS7


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Phase - 4

Phase 5


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Phase - 5


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WCDMA Ai I t f


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WCDMA Air Interface UE UTRAN CN

Mapping of Transport Channels and Physical Channels

Broadcast Channel (BCH)

Forward Access Channel (FACH)

Paging Channel (PCH)

Random Access Channel (RACH)

Dedicated Channel (DCH)

Downlink Shared Channel (DSCH)

Common Packet Channel (CPCH)

Primary Common Control Physical Channel (PCCPCH)

Secondary Common Control Physical Channel (SCCPCH)

Physical Random Access Channel (PRACH)

Dedicated Physical Data Channel (DPDCH)

Dedicated Physical Control Channel (DPCCH)

Physical Downlink Shared Channel (PDSCH)

Physical Common Packet Channel (PCPCH)

Synchronization Channel (SCH)

Common Pilot Channel (CPICH)

Acquisition Indication Channel (AICH)

Paging Indication Channel (PICH)

CPCH Status Indication Channel (CSICH)

Collision Detection/Channel Assignment Indicator

Channel (CD/CA-ICH)

Highly Differentiated Types ofChannels enable best combinationof Interference Reduction, QoSand Energy Efficiency,

WCDMA Ai I t f


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Common Channels - RACH (uplink) and FACH (downlink)

Random Access, No Scheduling

Low Setup Time

No Feedback Channel, No Fast Power Control, Use Fixed Transmission Power

Poor Link-level Performance and Higher Interference

Suitable for Short, Discontinuous Packet Data

Common Channel - CPCH (uplink)

Extension for RACH

Reservation across Multiple Frames

Can Utilize Fast Power Control, Higher Bit Rate

Suitable for Short to Medium Sized Packet Data

RACH

FACH 1 2 1 3

3P3 1P

1

CPCH1P

1

2P2

WCDMA Ai I t f


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Dedicated Channel - DCH (uplink & downlink)

Dedicated, Requires Long Channel Setup Procedure

Utilizes Fast Power Control

Better Link Performance and Smaller Interference

Suitable for Large and Continuous Blocks of Data, up to 2Mbps

Variable Bitrate in a Frame-by-Frame Basis

Shared Channel - DSCH (downlink)

Time Division Multiplexed, Fast Allocation

Utilizes Fast Power Control Better Link Performance and Smaller Interference

Suitable for Large and Bursty Data, up to 2Mbps

Variable Bitrate in a Frame-by-Frame Basis

DCH (User 1)

DCH (User 2)

DSCH 1 2 3 1 2 31

2 31 2

WCDMA Air Interface


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Summary

5 MHz Bandwidth -> High Capacity, Multipath Diversity Variable Spreading Factor -> Bandwidth on Demand

RACH

CPCH

DCH (User 1)

DCH (User 2)

DSCH

FACH 1 2 1 3

3P3 1P

1

1P1

2P2

1 2 3 1 2 31

2 31 2


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UTRAN


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UTRAN UE UTRAN CN

Node B

Node B

RNC

Logical Roles of the RNC

Controlling RNC (CRNC)Responsible for the load andcongestion control of its own cells

CRNC

Node B

Node B

SRNCServing RNC (SRNC)Terminates : Iu link of user data,Radio Resource Control Signalling

Performs : L2 processing of datato/from the radio interface, RRMoperations (Handover, Outer Loop

Power Control)

Drift RNC (DRNC)

Performs : MacrodiversityCombining and splitting

Node B

Node B

DRNC

Node B

Node B

SRNC

Node B

Node B

DRNC

UE

UE

Iu

Iu

Iu

Iu

Iur

Iur

Core Network UE UTRAN CN


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MSC/

VLR GMSC

SGSN GGSN

HLR

Ex

ternalNetworks

Iu-cs

Core Network, Release 99

CS Domain :

Mobile Switching Centre (MSC) Switching CS transactions

Visitor Location Register (VLR) Holds a copy of the visiting users

service profile, and the precise info

of the UEs location

Gateway MSC (GMSC) The switch that connects to

external networks

PS Domain : Serving GPRS Support Node (SGSN)

Similar function as MSC/VLR

Gateway GPRS Support Node (GGSN) Similar function as GMSC

Register : Home Location Register (HLR)

Stores master copies ofusers service profiles

Stores UE location on thelevel of MSC/VLR/SGSN

Iu-ps



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MSG MGW

SGSN GGSNExternalNetworks

Iu-cs

Core Network, R5

1st

Phase of the IP MultimediaSubsystem (IMS)

Enable standardized approach for IPbased service provision

Media Resource Function (MRF) Call Session Control Function (CSCF) Media Gateway Control Function (MGCF)

CS Domain :

MSC and GMSC Control Function, can control multiple

MGW, hence scalable

MSG Replaces MSC for the actual switching

and routing

PS Domain :

Very similar to R99 with someenhancements

Iu-ps

MSC GMSCIu-cs

MRF CSCF

HSS

MGCF

Services & Applications

Services & ApplicationsIMSFunction

IP

Multimedia

Subsystem

Example -QoS Requirement for Web Browsing


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Example -QoS Requirement for Web Browsing

A User Data Session

Log on

Session

begins

1st Packet Call

Inactivity timer

expired,call tear

down, resources

released

Data Transaction

inter-arrival time

Log out

Session

Ends

Data

Transactions

User Thinking Time

2nd

Packet

Call

Nth Packet Call

Inactivity timer

expired,call tear

down, resources

released

Inactivity

timer period

Call SetupCall SetupCall Setup

Inactivity

timer period

User tears

down the

call

Packets

Packet inter-

arrival time

Uplink

DownlinkUplink

Downlink DownlinkDownlink

Packet

Data

Calls

Dormant

mode

UMTS Bearer Services


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UMTS Bearer Services

TE MT UTRANCN IuEDGE

NODE

CNGateway TE

End-to-End Service

External Bearer

Service

Radio Access Bearer

Service

BackboneNetwork Service

UTRA

FDD/TDD

Service

TE/MT Local

Bearer ServiceUMTS Bearer Service

CN Bearer

Service

Radio BearerService

Iu BearerService

Physical Bearer

Service

UMTS

IP Multimedia Subsystem


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IP Multimedia Subsystem

The IMS provides the control of applications,control of sessions, and media conversion. session control services including subscription,

registration, routing and roaming

combination of several different media bearerper session

central service based charging

quality of service support

New applications Push-to-Talk over Cellular (PoC),

Presence and Instant Messaging

Voice and Video over IP.

UTRAN UE UTRAN CN


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UTRAN UE UTRAN CN

Protocol Model for UTRAN Terrestrial Interfaces

Application

Protocol

Data

Stream(s)

ALCAP(s)

Transport

Network

Layer

Physical Layer

Signaling

Bearer(s)

Transport

User

Network

Plane

Control Plane User Plane

Transport

User

Network

PlaneTransport Network

Control Plane

RadioNetwork

Layer

Signaling

Bearer(s)

Data

Bearer(s)

Derivatives :

Iur1, Iur2, Iur3, Iur4

Iub

Iu CS

Iu PS

Uu

Functions of Node B (Base Station)-Physical layer generator

Air Interface L1 Processing (Channel Coding, Interleaving, Rate Adaptation,Spreading, etc.)

Basic RRM, e.g. Inner Loop Power Control

References


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References

[3] 3GPP TS 23.009 version 5.0.0, Handover Procedures, December 2001.

[4] 3GPP TS 22.129 version 5.1.0, Service aspects; Handover Requirements between UTRAN and GERAN or other RadioSystems, December 2001.

Carl Andren A Comparison Of Frequency Hopping And Direct Sequence

Spread Spectrum Modulation, A Comparison For IEEE 802.11 Applications

[2] 3rd Generation Partnership Project, Technical Specification Group RAN,Working Group 4 (TSG RAN WG4), UE Radio

transmission and reception

(FDD), 3G TS 25.103, V2.0.0, September 1999

[6] http://www.umtsworld.com/technology/UMTSChannels.htm

[10] http://www.iec.org/

IEC online tutorials, UMTS

[11] Riku Jntti Lecture material WCDMA course, University of Vaasa, Finland,spring 2003.

http://www.uwasa.fi/~riku/opetus/wcdma.htm

[ [15] 3rd Generation Partnership Project, Technical Specification Group RAN,

Working Group 2 (TSG RAN WG2), Radio Resource Control (RRC)

protocol specification, 3G TR 25.331, V3.14.0, Release 99, March 2003

[16] http://www.umtsworld.com/technology/RCC_states.htm

Wcdma Umts-call Flow

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