01_mn3530eu35mn_0001_introduction.pdf

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Introduction Siemens/NEC

MN3530EU35MN_0001 2003 Siemens AG/NEC Corporation

1

Contents

1 Network elements 3

1.1 User equipment 4

1.2 Access network 6

1.3 Serving, drifting and controlling RNC 10

2 Geographical and UTRAN entity identifiers 17

2.1 Geographical identifier 18

2.2 UE identifiers 20

3 ATM basic 23

3.1 Introduction 24

3.2 ATM composite 50

3.3 SS7 over ATM 52

3.4 IP over ATM 58

4 UTRAN FDD measurement abilities 67

4.1 Introduction 68

4.2 Types of measurement items 70

Introduction


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Siemens/NEC Introduction

MN3530EU35MN_0001

2003 Siemens AG/NEC Corporation

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3

1 Network elements

3GMSC

SGSN

RNC

RNC

NodeB

NodeB

NodeB

NodeB

Uu

Uu

IuCS

IuPSIuB

IuB

IuR

GSM

UMTS

UMTS

Fig. 1 Network Overview


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1.1 User equipment

The User Equipment includes the mobile equipment i.e. the terminal equipment onthe one hand and the USIM or SIM on the other hand.

USIM

The USIM functions to save data and procedures in the terminal equipment. Itsupports call handling, contains security parameters, user-specific data, e.g.telephone directory entries, etc. The installed USIM is made available to thecustomer by the network operator and can be updated e.g. via SMS or cellbroadcasting.

Examples of USIM data and procedures

Data:International Mobile Subscriber Identity

Packet Switched Location Information

Security Information for authentication and ciphering for circuit and packetswitched applications

PLMN selector and HPLMN search period

Call meters

Display Languages

Telephone Directory

Forbidden PLMNsEmergency Call Codes etc.

Procedures:

Application related procedures

Security related procedures

Subscription related procedures

Mobile Equipment

The Mobile Equipment represents the partner of the Node B and of the RNC. I.e. it is

responsible for serving the radio interface. Some of the tasks of the MobileEquipment:

CDMA coding and encoding

Modulation demodulation on the carrier

Power control

Quality and field strength measurements

Ciphering and authorization

Mobility management and equipment identification


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UMTS Subscriber

identity module

Mobile Equipment

85298155

597868

*V0179

CDMA coding und encoding

Modulation Demodulation

Power control

Quality and Strength Measurement

Ciphering and Authorisation

Mobility Management

Equipment Identification

CDMA coding und encoding

Modulation Demodulation

Power control

Quality and Strength Measurement

Ciphering and Authorisation

Mobility Management

Equipment Identification

Data:Preferred Language

International Mobile subscriber identity

Call MeterAuthentication and ciphering

Forbidden PLMNs

Packet switched Location Information

Procedurers:Security related

Subscripton Related

Data Download

Image Download

Data:Preferred Language

International Mobile subscriber identity

Call Meter

Authentication and cipheringForbidden PLMNs

Packet switched Location Information

Procedurers:Security related

Subscripton Related

Data Download

Image Download

Fig. 2 User Equipment functions


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1.2 Access network

1.2.1 Node BA Node B is a physical unit for implementing a UMTS radio transmission. Dependingon the sectoring of the cells, one (omni) cell or multiple (sector) cells can be servicedby a Node B. Generally, up to six (60) cells are serviced by a Node B in UMTS. TheUMTS system is however also open for the use of so-called intelligent antennae thatallow particular UE to be pursued, thereby providing even greater system capacity(Space Division Multiple Access SDMA).

A Node B can be used for Frequency Division Duplex (Uplink and Downlinkseparated by different frequency bands), Time division Duplex (Uplink and Downlinkin different time slots) or dual mode operation.

A Node B converts user and signaling information received from the RNC fortransport via the radio interface, and in the opposite direction. This activity includessafeguarding the information against loss in addition to preparing it for CDMAtransmission and Radio Frequency handling.

Node Bs are involved in power control. The Node B also measures the signal noiseratio of the User Equipment, compares the value with a predefined one and instructsthe User Equipment to control its transmission power.

The Node B also measures the quality and strength of the links and determines theFrame Error Rate.


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Node B

Uplink Downlink control by:

FDD or TDD

Up to six cells are served

Power control

Signalling convertion

Error Correction

CDMA Transmission

Quality and Strenght

measurement

Softer Handover (Intra NB)

Uplink Downlink control by:

FDD or TDD

Up to six cells are served

Power control

Signalling convertionError Correction

CDMA Transmission

Quality and Strenght

measurement

Softer Handover (Intra NB)

FDD Frequency division duplex

TDD Time division duplex

CDMA Code division multiple access

Fig. 3 NodeB functions


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1.2.2 RNC

The RNC is the central control unit in the Radio Network Subsystem for a flexible

number of Node B's. The RNC is linked with the Core Network (CN), the Node Bs orother RNC's via the Iu, Iub and Iur interfaces.

The RNC's are independently responsible for Radio Resource Management (RRM) i.e., independent of the CN. RRM is taken to mean functions required for assigningresources and maintaining links.

The following are examples of RNC functions:

Power Control

Handover Control

Ciphering/deciphering

Protocol conversion

Admission Control

Congestion Control

Macro Diversity

geogr. Coordinates


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Radio Network Control

(RNC)

Node B

Node B

RNC

RNC

Core

Network

Power Control

Handover Control

Cipering/deciphering

Protocol conversion

Admission Control

Congestion Control

Macro Diversity

geogr. Coordinates

Power Control

Handover Control

Cipering/deciphering

Protocol conversion

Admission Control

Congestion Control

Macro Diversity

geogr. Coordinates

Node B

Fig. 4 RNC function


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1.3 Serving, drifting and controlling RNC

The RNC (Radio Network Controller) is the network element responsible for UTRANradio resource control. There is a very strict management principle in UTRAN.Together with these principles three terms, indicating the RNC functionality, areconnected to. Every RNC can support all three different functionalities. It depends onthe situation, which functionality has to be applied.

Controlling RNC

The first term, that is going to be discussed, is the controlling RNC (C-RNC). Everycell has one and only one C-RNC. The C-RNC of a cell is exactly the RNC that isconnected with the Node B serving the cell. The tasks of the controlling RNC coversthe following areas:

admission control based on UL interference level and DL transmission power,

system information broadcasting,

allocation / de-allocation of radio bearers,

data transmission and reception.

congestion control in its own cell

Power control and

Resource allocation and admission control for new radio links to be establishedin those cells

Summary:

The CRNC is the RNC controlling a Node B (i.e. terminating the Iub interface towardsthe Node B).

This means the controlling RNC of a cell is responsible for all lower layer functionsrelated to the radio technology.


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cell

Node B

cRNC

Iub

Controlling RNC

-admission control

- system information broadcasting

- radio bearer allocation / release

( code allocation / release)

- data transmission and reception

Fig. 5 Controlling RNC functionality

RNS

CRNC

NodeB

NodeB

Fig. 6 Controlling RNC


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Serving RNC

For UTRAN the following principle is applied. An UE that is attached to an UTRAN isserved by one and only one RNC. This RNC is called the serving RNC (S-RNC). The

existence of a serving RNC does not imply that the UE is camped on a cell belongingto the S-RNC. The serving RNC handles all higher layer functions related to radioaccess and information transport through UTRAN. In detail the S-RNC performs thefollowing functions:

the S-RNC handles the Iu interface towards the CN for this UE,

the S-RNC handles the complete radio resource control for this UE,

location / mobility handling

ciphering,

backward error correction (layer 2 functionality).

Radio bearer control,

Handover decision,

Power control.

Summary:

The SRNC for one mobile is the RNC that terminates both the Iu link for the transportof user data and the corresponding RANAP signaling to/from the core network per

mobile.The SRNC terminates the RRC signaling (signaling protocol between UE andUTRAN).

It performs the data L2 processing to/from the radio interface and establishes theconnection between UE and the core network.

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Node B

sRNC

Iub

Serving RNC

-Iu interface controlling

- radio resource control

- location / mobility handling

- encryption / integrity check

- backward error correction

- combining / splitting of data

streams

Node B

dRNC

Iub

CN

Iur

Iu

UE

Fig. 7 Serving RNC functionality

NodeB CN

RNS

SRNC

Iu userdata link

Iu signalinglink

NodeB

Fig. 8 Serving RNC


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Drift RNC

In UMTS it is possible that one UE is connected to more than one cell, or connectedto a cell, that does not belong to the S-RNC. This means the UE is connected with a

cell controlled by a RNC different to the S-RNC. This foreign RNC is called drift RNC(D-RNC). In principle the D-RNC is the C-RNC of a cell the UE is connected to, butits not the S-RNC. Therefore the D-RNC performs the C-RNC functions for the cellsnot controlled by the S-RNC.

When a D-RNC is involved for a UE, then the data streams between UE and UTRANand UE-CN always pass the S-RNC. In the downlink the S-RNC sends the data toown cells and to the D-RNC (soft handover), this is called splitting. The UE receivesall the data streams from the cells, it is connected to, and adds them together (RAKEreceiver). In the uplink the S-RNC receives data from the own cells and from the D-

RNC. Here the S-RNC combines the data streams. This combination is performed bythe S-RNC in the following way : the S-RNC takes only the data frame with thesmallest bit error rate, all other data frames will be discarded.

The usage of a D-RNC requires a Iur interface between D-RNC and S-RNC.Because the implementation of an Iur interface is optional, it is a matter of networkplanning, whether the usage of D-RNCs is allowed or not. The interface itself doesnot need to be a physical line, it can be implemented via virtual paths or virtualchannels.

Summary:

It is any RNC, other than SRNC that controls cells used by the mobile. The DRNCperforms macro-diversity combining and splitting, if necessary. The DRNC does notperform user plane data L2 processing, but routes the data transparently between theIub and Iur interfaces. The UE can be connected to zero, one or more DRNCs.

Macro diversity is an operation state in which a UE simultaneously has radio linkswith two or more UTRAN access points.


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NodeB

NodeB

NodeB

CN

RNS

RNS

DRNC

SRNC

Iuinterface

Iur interface:User data andsignaling

NodeB

Fig. 9 Drift RNC


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2 Geographical and UTRAN entity identifiers


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2.1 Geographical identifier

As in GSM there is a need to address different physical, geographical or logicalentities within UMTS. Here first of all the geographical and physical entities ofUTRAN will be described.

PLMN Id =MCC + MNC:

The PLMN-ID is used to address a PLMN in a world wide unique manner. As in GSMthe PLMN-ID consist of a MCC (mobile country code) and a MNC (mobile networkcode). MCC and MNC are allocated by ITU-T and are specified within ITU-T E.212.

CN-Domain Ids :

CS- and PS core network introduce their own regional area concept. This is theconcept of Location Area for CS and the concept of Routing Area for PS. This exactlythe same as in GSM/GPRS. We have:

LAI = PLMN-ID + LAC (Location Area Identity/Code)

RAI = PLMN-ID + LAC + RAC (Routing Area Identity/Code)

RNC Id:

Every RNC node has to be uniquely identified within UTRAN. Therefore every RNCgets a RNC-ID. Together with the PLMN-ID the RNC-ID is unique world wide. TheRNC-ID will be used to address a RNC via Iu, Iur and Iub interface. For the servingRNC the identifier is called S-RNC-ID, for the drift RNC it is denoted as D-RNC-IDand the controlling RNC has a C-RNC-ID. For one RNC node these identifiers arealways the same. The RNC identifier itself is allocated by O&M.

Global RNC-ID = PLMN-ID + RNC-ID

Cell Id and UTRAN Cell Id:

The cell ID C-ID is used to address a cell within a RNS. The cell ID is set by O&M inthe C-RNC. Together with the RNC-ID the cell ID forms the UTRAN cell ID UC-Id.

UC-ID = RNC-ID + C-ID


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Local Cell Identifier

The local cell identifier is used in the Node B to identify resources. There is a uniquerelation UC-Id to local cell identifier.

Service Area Id :

Several cells of one location area can be defined to form a service area. Such aservice area is identified with a SAI (service area id):

SAI = PLMN-ID + LAC + SAC

It can be used to support location based services.

URA ID :

The UTRAN introduces its own are concept next to LA and RA. This is the UTRANregistration area

LAIPLMN-ID LAC (2byte)

RAIPLMN-ID LAC (2byte)RAC (1byte)

Global

RNC-IDPLMN-ID RNC-ID (12 bit)

UC-IDCRNC-ID (12 bit) C-ID (28 bit)

SAIPLMN-ID LAC SAC (2 byte)

URA-IDURA ID (2 byte)

Location Area

Routing Area

RNC

UTRAN cell ID

Service Area

UTRAN registration

area

Fig. 10 UTRAN geographical and UTRAN entity identifier


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2.2 UE identifiers

The UE and the subscriber can have several identifiers for the PLMN. Typically wecan distinguish two types of identifiers according to the point of generation of theidentifier:

2.2.1 Core network identifiers

NAS (non access stratum) identifiers: These identifiers are allocated by the corenetwork. In detail there are IMSI, TMSI and P-TMSI (and IMEI).

2.2.2 UTRAN identifiersUTRAN identifiersare always temporary. This means they are allocated to the UEfor the time of the need. After the last procedure the identifiers are released.

In this chapter only the UTRAN identifier are of interest. It is a typical principle incommunication and computing systems that every entity working on a specific task,allocates its own identifier and handler. This is also the case for UTRAN. EveryUTRAN entity like RNCs and Node Bs will provide their special identifier for the UE.These identifiers are called Radio Network Temporary Identifier (RNTI). There arefour types of RNTIs:

s-RNTI: The s-RNTI is allocated by the serving RNC. The S-RNC uses the s-RNTI toaddress the UE. The D-RNC uses the s-RNTI to identify the UE to the S-RNC. ThesRNTI uniquely addresses the UE in the S-RNC.

d-RNTI: The d-RNTI is allocated by a D-RNC, but the d-RNTI is never used on theair interface Uu. Instead the S-RNC uses the d-RNTI to identify the UE to the D-RNC.The d-RNTI uniquely identifies the UE in the D-RNC.

c-RNTI: The c-RNTI is allocated by a controlling RNC when the UE accesses a newcell of this C-RNC. The c-RNTI is unique in the cell. The corresponding C-RNC shallbe able to translate the c-RNTI into sRNTI (if C-RNC=S-RNC) or into d-RNTI (if C-RNC=D-RNC). The c-RNTI is used by UE to identify itself to the C-RNC, and is usedby the C-RNC to address the UE.

u-RNTI: The u-RNTI (UTRAN RNTI) consist of RNC-Id and s-RNTI

u-RNTI = RNC-ID + s-RNTI.

So the u-RNTI is unique world wide. The u-RNTI will be used by UE and S-RNC toidentify the UE on common radio channels and during paging and cell access.


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u-RNTI or

c-RNTI B, C

Node B

sRNC

Iub

Node B

dRNC

Iub

CN

Iur

Iu

UE

s-RNTI

d-RNTIs-RNTId-RNTI

c-RNTI B, Cd-RNTIs-RNTI

c-RNTI A

u-RNTI or

c-RNTI A

RNTI

-allocated by RNCs

- 16 bit length

(u-RNTI 32 bit)

-used within UTRAN

and on Uu only

Fig. 11 RNTIs and their usage within UTRAN


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3 ATM basic


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3.1 Introduction

In the W-CDMA (Wide Band Code Division Multiple Access) system, ATM(Asynchronous Transfer Mode) is used as transport technology to carry voice anddata between Node-B, RNC and Core Network.

ATM technology is based on the efforts of the International Telecommunication UnionTelecommunication (ITU-T) to develop Broadband Integrated Services DigitalNetwork (B-ISDN) at high speed.


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GMSC : Gateway MSC MSC : Mobile Service Switching Center

GGSN : Gateway GPRS Support Node SGSN: Serving GPRS Support Node

CN : Core Network RNC : Radio Network Controller

RNS : Radio Network Subsystem UE : User Equipment

USIM : UMTS Subscriber Ident ity Module ME : Mobile Equipment

UTRAN : UMTS Terrestrial Radio Access Network VLR : Visitor Location Register

HLR :Home Location Register

CN

USIM

ME

UE

RNS

Uu

Cu

RNC

RNS

Iur

IuCS

IuPS

Iub

HLR

PSTN

ISDNMSC

/VLRGMSC

GGSN

NodeB

Node

B

RNC SGSN

Internet

Node

B

Node

BATM

ATM

A

T

M

ATM ATM

SS7

SS7

IP

S

S

7

Fig. 12 ATM interfaces


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3.1.1 ATM main points

The definition of ATM is as follows:

Information streams from various media (analog or digital) are segmented intoheaded fix length packets called cells.

The cells are multiplexed and transmitted through an ATM switch. In otherwords, different speeds information from various media is transmitted throughthe same switch.

The cells are routed through the switch in accordance to their routing bits,allocated in their cell header.

Cells are generated only when there is information to be sent. Otherwise idle ornull cells are inserted in the cell stream.

The cells arrive at the destination in the same sequence as it was sent from thesource terminal.


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VOICE

DATA

VIDEO

ATM CellATM Cell

constant

variable

ATM

SWITCHVOICE

DATA

constant

variable

CELLDEASSEMBLING

CELLASSEMBLING

VIDEO

ATM Cell HeaderATM Cell Header

Fig. 13 ATM Function


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3.1.2 ATM and STM

3.1.2.1 STM (Synchronous Transfer Mode)

STM is the standard technique that, assign time slots or channels, which areperiodically multiplexed. The interval between cells (time slots), which have the samedestination is synchronous. Furthermore, the time slots are distributed in accordancewith its position in the frame of 125us.

The next figure illustrates the STM multiplexing function. For each user a fixed lengthtime slot is assigned and transmitted through the STM switch. The switching is timeslot by time slot (8 bit per time slot).


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The capacity of each

channel is fixedCh

1

Ch2

Ch3

Ch4

SynchronizationConstant time slots

Frames(125us) Frames

Fig. 14 STM Multiplexing


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3.1.2.2 ATM (Asynchronous Transfer Mode)

Supports constant and variable traffic, which is put into 53 bytes fixed length cells

and multiplexed. A header (H) with destination information is added to each cell to bedistributed according to this header address information. The interval between cells,which have the same destination, is asynchronous.

The next figure illustrates the ATM multiplexing function. For each user a virtualchannel is assigned (in this example 4). The virtual channel has differenttransmission capacity depending on type of service requested by the user. The cellsare transmitted trough the ATM switch, where is switched cell by cell.


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Idle cell

1

2

3

Virtual

Ch. 4

Fixed length cells are transmittedasynchronously

Header

The capacity of each path is

different

Fig. 15 ATM Multiplexing


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3.1.3 ATM cell structure

ATM cell is 53 bytes fix length, consisting of 48 bytes information payload and 5

bytes header. The header is used to route the cells into appropriate virtual paths(VP) and virtual channels (VC) preserving cell sequence integrity per virtual channel.

Basically there are two types of interfaces:

User Network Interface (UNI) : Interface between user and the node

Network Node Interface (NNI) : Interface between node to node

The difference among them is the Virtual Path Identifier (VPI). UNI interface uses 8bits to identify the virtual path, while NNI uses 12 bits. In W-CDMA both interfaces

UNI and NNI are used.


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User Information

User Information

Node-B

R

NC

CNUNI NNI

Header5B

Payload

48B

GFC VPI

VPI

VCI

VCI

HEC

VCI

VCI

PT CLP

VPI VPI

VPI

VCI

VCI

HEC

VCI

VCI

PT CLP

Fig. 16 ATM Cell Structure


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Cell Header Parameters

GFC (Generic Flow Control): 4 bits (Not used for W-CDMA system). Originallydesigned for terminal racing control in the bus-type connection, GFC is under

research to be used as flow control in the star-type connection.

VPI (Virtual Path Identifier) & VCI (Virtual Channel Identifier) VPI 8 bits (at UNI),12 bits (at NNI) VCI 16 bits

The VCI and VPI are used to route information between switches. VCI and VPI arenot addressed. They are explicitly assigned at each segment within a network.

PT (Payload Type): 3 bits (Not used for W-CDMA system) PT discriminatesbetween user data or control data. Also, indicates congestion status or last cellin a single AAL5 frame data cell series.

CLP (Cell Loss Priority): 1 bit (Not used for W-CDMA system) Indicates discardcell priority.

HEC (Header Error Check): 8 bits Header field error detection or 1-bit errorcorrection. Error detection mode: Two bits Error in the header will be discarded.Error correction mode: Header's one bit error is corrected.


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3.1.4 Virtual Path Identifier (VPI) and Virtual Channel Identifier(VCI)

The VCI and VPI are used to route information from one switch to another. VCI andVPI are not addresses. They are explicitly assigned at each segment within anetwork.

The VCI label is used to identify a connection between two ATM switches. The VCIlabel in an ATM cell may change at intermediate nodes within a route. This is due tothe fact that network nodes have their own VCI label. The user has no way ofchoosing a particular VCI label, because it is assigned to the user from the ATMnode. The 16 bits VCI label is randomly assigned to the user at the ATM node toidentify connection between two points.

A physical link can have one or more virtual paths and a virtual path includes one ormore virtual channels.

32

Virtual Path

Connection

Pre-assigned VC

ForUser

VC

Virtual ChannelConnection

0 Unassigned Cell (VPI=0)

1

2

3

4

5

6

7

.

31

Meta-signaling

Broadcast Signaling

OAM Cell (segment)

OAM Cell (end to end)

Signaling

VP Resource

Reserved

Reserved

Users and OAM cells

(For WCDMA)

VC

VC

VC

VC

VC

VC

DefaultVCAllocation

Physical CablePhysical CablePhysical CableVP

Fig. 17 VPI/VCI Assignment


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3.1.5 Mechanism of VPI and VCI

The ATM switches use the headers VPI and VCI fields to identify the routing for each

cell. To illustrate the switching mechanism the next figure shows three elements thephysical port, VPI and VCI relationship.

3.1.6 Connection types

To establish the signaling path and the traffic path, WCDMA system uses two typesof connections: Permanent Virtual Connection and Switched Virtual Connection.

3.1.6.1 Permanent Virtual Connection (PVC)

PVC is a connection type between two nodes. Both of the endpoint VCs is manuallyassigned in advance at ATM switch. The link-by-link route through the network is alsomanually provisioned. If any equipment fails, the PVC is down. So PVC is a VC,which is statically mapped at every point in the ATM network.

3.1.6.2 Switched Virtual Connection (SVC)

SVC is established by UNI/NNI signaling methods and it is a demand connection.The connection is set up by interchanging signals between nodes, through signalingchannels. The CPU receives the signals and controls the channel switching by the

ATM switch.


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Input Data

Port VPI VCI

1 1 80

1 4 40

Output Data

Port VPI VCI

5032

4053

1

2

ATM Switch

Port 2

2

Port 1 Port 3

1

VC80 VC50

V

P

5

VC40

VC50

VP3

V

P4

VP1

VC40

VC80

Fig. 18 Mechanism of VPI/VCI

Node 1

Node1

control

Node2

Node2

control

SVC SVC

PVC PVC

CPU CPU

Fig. 19 PVC and SVC Connection


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The next figure illustrates the PVC and SVC connection for the RNC. The RNC PVCconnection is used for the signaling link between Node B and MSC. On the otherhand the SVC connection is for the traffic path.

The PVC is established once by the maintenance people and remain connected .TheSVC connection is established by the processor according to the signalinginformation coming from Node B or MSC. The processor after receiving the signalinginformation changes the routing table of the ATM switch in order to connect the cellsto the specific destination. After the call disconnection the processor releases thetraffic path.


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y

M

SC

ATM SW

ATM SW

Signaling

N

OD

E

B

VPIm

VCIn

VPIp

VCIqVCIr

SignalingCPU

RNC

SVC

PVC

Signaling path

Traffic path

VCIm

VCIn

V

Pl

m

VP

lm

VCIn

VCIq

VCIr

V

Pl

n

V

P

lp

Fig. 20 PVC and SVC connection in RNC


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3.1.7 ATM cell flow in RNC

The RNC interfaces the Core Network, Node-B and other RNC to send/receive ATM

cells. These cells are not standard format as usual ATM systems but they arecomposed of several user information in one cell, called Composite Cell.

The composite cells arriving from different interfaces are decomposed inside theCMP (Composite/De-composite) unit into standard cell format to be processed.After the information is processed, the cells are composed again and transmitted tonext node.


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RNC

ATM

SW

Trunk

CMP

Composite ATMCell

StandardATMcell

CN

Node-BCMP

StandardATMcell

Composite ATM

Cell

Fig. 21 ATM Cell Flow


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3.1.8 ATM protocol stack

The ATM architecture uses a logical model to describe the functionality it supports.

The reference model illustrated in next figure is composed basically of the followingplanes and layers.

3.1.8.1 ATM planes

User Plane:

Responsible for transfer, flow control and recovery operation of user information

Control Plane:

Responsible for setting up, releasing and managing network connections. Needed forSVC (Switched Virtual Connection) set up.

Management Plane:

This plane has two functions

Plane Management: Responsible for coordination of all planes. Also managesthe whole system and has the function to interchange information betweenControl Plane and User Plane.

Layer Management: This plane monitors the normal function of each layer andperforms operation, administration and maintenance service.


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L3

OSI Layer

L2

L1

PHYSICAL LAYER

ATM LAYER

AAL LAYER

Upper LAYER

AAL LAYER

Upper LAYER

MANAGEMENT PLANE

Control

Plane

User

Plane

Layer

Management

Plane

Management

Fig. 22 ATM Protocol Stack


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3.1.8.2 ATM layers

The ATM system can be divided into four layers (Physical Layer, ATM Layer, ATM

adaptation Layer and upper layer).

Physical Layer (PHY):

This layer transports ATM cell from one point to another using a physical medium(metallic cable, optical cable etc). Moreover, controls bit flow and cellsynchronization.

ATM Layer:

This layer provides the switching and routing of the ATM packets according to theirVCI and VPI information. It also generates the cell header information and extracts it

from received data.

ATM Adaptation Layer (AAL):

This layer maps various types of traffic into and out of ATM cells. There are differenttypes of adaptation layers according to the traffic type.

Upper Layer:

Controls the signaling protocol as well as user and specific application protocols forthe data to be transmitted.


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User data to be transmitted

Request

Request

Request

ATMLayer

AAL

Layer

Upper

Layer

53 B 53 B 53 B

Payload H Payload H Payload H

PHY

Layer

48 bytes 48 bytes 48 bytes

Transmit cells using

metallic or optical cable

5B header is added toeach 48B segment

User data is divided into

48B segment

Edit user data

VP (2 Mbps, 155 Mbps, etc.)Physical Cable

Fig. 23 ATM Layer Function


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3.1.9 ATM Adaptation Layers (AAL) types

RNC system uses different kind of AAL depending on voice or control data

information to be transmitted. Mainly AAL2 and AAL5 are used in W-CDMA betweenNode-B, RNC and Core network and also AAL3/4 type is used for internal process inthe RNC.

Definition of service categories of AAL

CBR (Constant Bit Rate):

This service is used by connections that request a static amount of bandwidth that iscontinuously available during the connection lifetime. This amount of bandwidth is

defined by a Peak Cell Rate (PCR) value. CBR supports real time applicationsrequiring tightly constraint delay variation (e.g. voice, video etc).

VBR (Variable Bit Rate):

This category is for real time applications requiring tightly constraint delay and delayvariation; its appropriate for voice and video applications. Real time VBRconnections are characterized in terms of a Peak Cell Rate (PCR), Sustainable CellRate (SCR) and Maximum Burst Size (MBS) values.

UBR (Unspecified Bit Rate):Used for non-real-time applications not requiring tightly constraint delay and delayvariation. Traditional computer communications applications such as file transfer andemail are some examples.

ABR (Available Bit Rate):

The networks transfer characteristic may change after connection establishment.Source rate change and ATM layer characteristic change are controlled by a flowmechanism. On the establishment of an ABR connection, the end system shallspecify to the network both a maximum required bandwidth and a minimum usable

bandwidth.


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3.1.10 AAL2 and AAL5 layer difference

AAL2:

Used for circuit switched user data (Voice) in Iu interface and user data (Voice andPacket Data) in Iub interface.

AAL5:

Used for transport control information in Iu and Iub interface and packet switcheduser data (Packet Data) in Iu interface.


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Voice ControlVoiceControl

AAL2 Cell Format AAL5 Cell Format

C

RC

L

I

P

AD

Control signals

Included sequence number

N (S)

Information CID

U

UI

L

I

H

EC

Node-B

R

N

C

MS

C

CID : Channel Identifier LI : Length Indicator

HEC: Header Error Contro l UUI : User to User Ind icator N(S) : Sequence number CRC : Cyc lic redundancy check

Fig. 25 AAL2 and AAL5 payload


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3.2 ATM composite

3.2.1 ATM composite functionThe purpose of composite cell is to transmit efficiently the information of severalusers in one cell. In standard ATM system, users transmit voice or data in a cell, butnot all bytes carry information .By these method unnecessary bytes in a cell areremoved and replaced by another users valid information achieving low packet delayand high bandwidth efficiency. The composite cell in WCDMA is the AAL2.

3.2.2 Composite cell structure

The composite cell is composed of different users information in a cell. The cellbegins with the ATM header (5 bytes) for routing, followed the STF (Start Field) 1byte field for user-to-user information discrimination and 3 bytes for users headerfield.

The STF is composed of:

OSF (Off Set):This skips prior remained packet information and points the beginningof new first AAL2 packet that starts transmission inside the current composite ATMcell(6bits).If there is no user data indicates the starting point of PAD

SN (Sequence Number):Identifies cell loss (1 bit)

P (Parity):Detects bit error (1 bit)

The user header is composed of:

CID (Channel Identifier):Identifies individual connections

LI (Length Indicator):Indicates number of bytes in payload

UUI (User to User Indicator):Transparently conveys information at upper layers

HEC (Header Error Control):Detects headers errors


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N

O

D

E

B

N

OD

E

B

53 bytes

(

p)

(

h

)

ATM Composite Cells

53 bytes

User

B (l)

User

D

ATM Composite Cells

MS

C

H

ea

de

r

H

e

a

de

r

H

e

a

de

r

H

ea

de

r

User

AUser

C

User

CUser

D

User

AUser

B

User A

User C

User B

User D

RN

C

Fig. 26 Composite Cell Function

R

N

C

User header

CID

(8b)

LI

(6b)

UUI

(5b)

HEC

(5b)

Start Field

OSF

(6b)

SN

(1b)

P

(1b)

ATM

Header(5B)

S

TF

UserData

AHe

a

der

(3b)

UserData

BHe

a

der

(3b)

PA

D

Fig. 27 Composite Cell Structure


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3.3 SS7 over ATM

3.3.1 Idea of SS7 (Signaling System No.7)The SS7 is a type of common channel signaling system that permits to transferringsignaling information of many calls in the form of data via a separate signalingchannel. Using a separate data link we can transmit signal data at high speed andlarge volume of information.

Advantages of common channel signaling system:

Allows more different kind of signals to be transferred in larger volumes.

Allows signals to be transferred at high speed (64 Kbps).

Allows transfer of information other than call connection information.

The common channel signaling system is divided into four levels named as level 1, 2,3 and 4:

LV1:Defines the physical, electrical and functional characteristics of a signalinglink.

LV2:Mainly provides error detection and error correction by retransmission.Functions are: Flag(F),Forward sequence number(FSN),Backward sequencenumber (BSN),error check (CK)

LV3:Provides signaling message handling function and signaling networkmanagement. Function of this level is the Routing Label. This is composed ofthe Service Information Octet (SIO), Destination Point Code (DPC), Orig9inatingPoint Code (OPC) and Signaling Link Code (SLC).

LV4:Consist of different user parts that define the functions and procedures ofthe signaling system.

Next figure shows the SS7 signaling message format and function per each level.The thick dark field means the function of the respective level.


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F FCK User part data

ROUTING

LABEL FSN BSN

F

I

B

B

I

B

FUser part data ROUTING

LABELFSN BSNF

I

B

BI

B

FUser part data

ROUTING LABEL

FSN BSNFI

B

BI

B

ROUTING

LABEL

FCK

F CKS

LC

O

PC

D

PC

SI

O

L

V

1

FFSN BSNF

IB

B

IB

F

CK

L

V

2

L

V3

L

V

4

User Part Data

S

I

O

S

I

O

S

IO

Fig. 28 SS7 Level Structure

BIB: Backward Indicator BitFSN: Forward Sequence NumberBSN: Backward Sequence NumberOPC: Origination Point CodeCK: Check BitSIO: Signal Information OctetDPC: Destination Point Code

SLC: Signaling Link CodeF: FlagSLS: Signaling Link SelectionFIB: Forward Indicator Bit

Fig. 29 Abbreviation


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3.3.2 Point codes

In the common channel signaling system, nodes are identified by unique number. It is

called point code (PC).

There are two types of point code:

OPC (Originating point code):To identify the originating office

DPC (Destination point code):To identify the destination office

Moreover, each switching is identified according to the type of signaling office:

SP (Signaling point): Originates and terminates the signaling information used forthe call connection.

STP (Signaling transfer point): Its describes, transfer signaling information to thefinal destination according to the DPC in the routing label field


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SP1

STP

A

STP

B

PC= OPC PC= DPC

SP2

Link group

Link group

Max. 16

links

Link group

Link group

Voice

SignalingInformation

DTI DTI

Fig. 30 Basic Signaling No.7 Network


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3.3.3 Signaling System No.7 over ATM

The signaling information on the Iu (MSC-RNC) and Iur (RNC-RNC) is called SS7

over ATM. So it means that ATM physical layer acts as SS7 level 2 function (not LV2hardware is necessary in RNC).

In RNC, LV3 and LV4 fields of SS7 are transmitted on the ATM cells. But SS7 LV2fields are not transmitted since there is not LV2 hardware. AAL layer segments theLV3 and LV4 information into 48 bytes, place it in the payload of each cell andtransmitted to the next node by the physical layer at 155 Mbps.


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M

S

C

R

N

C

F CKUser Part Data F

S

N

B

S

N

F

I

B

B

I

B

FROUTING

LABEL

53 bytes 53 bytes53 bytes

SS7

A

T

M

PAYLOAD

H

PAYLOAD

H

PAYLOAD

H

Fig. 31 Idea of SS7 over ATM


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3.4 IP over ATM

3.4.1 Idea of IP (Internet Protocol)Communication between computers needs common language to establish aconnection. Internet protocol is like a language that computers speak .It is a set ofrules that defines how two computers can send data to each other. This set of rules iscalled a protocol and multiple protocols that are grouped together form a protocolstack.

3.4.2 Feature of IP

Widely published open standard:It is not proprietary or owned by any corporation. Because it is a standard publishedprotocol.

Compatible with different computer systems:

It is like a universal language that would enable people from any country tocommunicate effectively with people from any other country

Works on different hardware and network configurations

Routable protocol

Reliable and efficient data delivery Single addressing scheme:

IP uses a single and relatively simple addressing scheme.


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NETWORK

DataData

e-mail

Source

IP address

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IP address

Internet Protocol

User Data

Trailer

Hea

der

TX Port No.RX Port No.

IP Header

TCP/ UDP

Header

Fig. 32 Idea of IP


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3.4.3 IP protocol stack

The IP protocol is on base of OSI (Open Standard Interconnection) model.

OSI model has seven layers as follows:

Application layer: The purpose of the application layer is to managecommunications between applications. Supports applications for communicatingover the network

Presentation layer: Formats data so that it is recognizable by the receiver.

Session layer: Establishes connections, and then terminates them after all thedata has been sent.

Transport layer: Provides flow control acknowledgments and retransmission ofdata when necessary.

Network layer: Adds the appropriate network addresses to packets.

Data Link layer: Adds the MAC addressee to packets

Physical layer: Transmits data on the wire

3.4.4 Interrelation of each layer

The purpose of each layer in the OSI model is to provide services to the layer aboveit while shielding the upper level from what happens below. The higher layers do not

need to know how the data got there or what happened at the lower layers.The following figure shows how data moves through the seven layers of the OSImodel from two hosts. Host A is transmitting data onto router. As the data movesdown from the seven layers toward the router, each layer puts a little bit ofinformation called header on the packet. The exact contents of each header dependon the protocols enabled at each layer.


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Physical

Data Link

Network

Transport

Session

Presentation

Application

Wire, Coaxial cable, Radio signals, Optical cable

LLC (Logical Link Control)

MAC (Media Access Control)

IP (Internet protocol)

ARP (Address Resolution Protocol)

TCP (Transmission Control Protocol)

UDP (User Datagram Protocol)

FTP (File Transfer Protocol)SMTP (Simple Mail Transfer Protocol)

SNMP (Simple Network Management)

DNS (Domain Name System)HTTP (Hypertext Markup Language Transfer Protocol)

TELNET

OSI Model

L1

L2

L3

L4

L5

L6

L7

Fig. 33 IP Protocol Stack

Physical

Data Link

Network

Transport

Session

Presentation

Application

Data

Data

Data

Data

Data

Data

Data

Host BHost A

Data

Header

Physical

Data Link

Network

Transport

Session

Presentation

Application

Data

Data

Data

Data

Data

Data

Data

Physical

Data Link

Network

Data

Data

Data

Router

Fig. 34 Interrelation of each Layer


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3.4.5 IP over ATM

Unlike SS7, all IP information is transmitted over ATM cells. The next figure illustrates

the IP message format and how it is transmitted over ATM.

IP header and TCP/UDP header are mainly composed of following data:

IP Header

SA (Source Address): Sets IP address (32 bit: IPv4) for sending terminal

DA (Destination Address): Sets IP address (32 bit: IPv4) for receiving terminal

TCP Header

TX (Transmit) port No.: Set port number for transmit side

RX (Receive) port No.: Set port number for receive side

3.4.6 IP address

IP address is used for IP Datagram routing process through a network.

Each host on a TCP/IP network is assigned a unique 32-bit logical address that isdivided into two main parts: the network number and the host number.

The 32-bits IP address are divided in groups of eight bits, separated by a dot and

expressed in decimal format. Each of the eight bits has its binary weight (128, 64, 32,16, 8, 4, 2, 1). The minimum value expressed by one octet (8 bits) is zero and themaximum value is 255.


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53 bytes 53 bytes 53 bytes

RN

C

SG

S

N

HPAYLOADPAYLOAD H PAYLOAD H

TCP/UDP Header

(8B)

TX

Port No.

RX

Port No.

IP Header

(24B)

Other DA SA

User Data

Session LayerPresentation Layer

Application Layer

Fig. 35 IP over ATM

IP Address=129.2.2.70IP Address=128.2.2.60

Source Address Destination Address

Computer NetworkComputer Network

(Internet)(Internet)

host

NetworkNetwork=128 Network=129

Fig. 36 IP Address


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3.4.7 IP address classes

IP address is divided into five classes: Class A, Class B, Class C, Class D and Class

E. All addresses are placed in a particular class based on the decimal values of theirfirst octet (1 to 255)

Class A: For this class 7 bits are assigned to network and 24 bits for host address.The range is from 0.0.0.0 to 127.255.255.255.

Class B:For this class 14 bits are assigned t network and 16 bits for host address.

Class C:For this class 21 bits are assigned to network and 8 for host address.

Class D:Not used.

Class E: Not used

3.4.8 Port no.

Port number identifies upper-layer applications during data transmission betweensource and destination. Port number 0 ~ 1023 are fixed for specific service (Well-known Port Number).

Next figure illustrates the port number assigned for TCP protocol:

Port =80 for HTTP (World Wide Web HTTP)

Port =23 for Telnet

Port =25 for SMTP (Simple Mail Transfer Protocol)

Port =110 for POP3 (Post Office Protocol-Version 3)


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0 Network 7 bits Host 24 bits

Network 14 bits Host 16 bits

Network 21 bits Host 8 bits

1 0

01 1

Class A ( 0.0.0.0 ~ 127.255.255.255 )

Class B ( 128.0.0.0 ~ 191.255.255.255 )

Class C ( 192.0.0.0 ~ 223.255.255.255 )

Class D ( 224.0.0.1 ~ 239.255.255.255 )

Class E ( 240.0.0.0 ~ 255.255.255.255 )

Not defined (for experiment use)11 1 1

For multicast address (invalid for any workstation or host)11 1 0

Fig. 37 IP Address Class

Upper layer Applications

Layer 1

Layer 2

Layer 3

Layer 4

HTTP SMTPTelnet

80 23 25 110

GTPUPOP3

2152

Fig. 38 Port Number

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