3g message flow

[Type text] MOBILE APPLICATION DEVELOPMENT

WIRELESS COMMUNICATION CHIPSETS AND MOBILE DEVICES

DIGITAL SIGNAL PROCESSING AND DATA ACQUISTION

WIRELESS TEST AND MEASUREMENT

M2M COMMUNICATIONS

WIRELESS APPLICATIONS

3G





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Contents 1. Introduction to UMTS ............................................................................................................................... 4

1.1 UMTS Network Architecture ............................................................................................................... 5

1.1.1 Basic Structure of UMTS Network ............................................................................................... 5

1.1.2 Architecture Overview ................................................................................................................ 6

1.1.3 User Equipment ........................................................................................................................... 7

1.1.4 UMTS Radio Access network........................................................................................................ 7

2. UMTS Core Network ............................................................................................................................... 13

2.1 Structure of UMTS Core Network ..................................................................................................... 13

2.2 IP Multimedia Sub-System ............................................................................................................... 15

2.3 Home PLMN ...................................................................................................................................... 18

2.4 Home Location Register .................................................................................................................... 18

2.5 Authentication Center (AuC) ............................................................................................................. 19

2.6 Equipment Identity Register(EIR) ...................................................................................................... 19

2.7 Mobile Switching Center ................................................................................................................... 20

2.8 Visitor Location Register(VLR) ........................................................................................................... 20

2.9 Gateway Mobile Switching center (GMSC) ....................................................................................... 20

3. UMTS N/w Transaction ........................................................................................................................... 21

3.1 Iub – Node B Setup ........................................................................................................................... 22

3.2 Message Flow .................................................................................................................................... 23

3.3 Iub – Iu – Loaction Update ................................................................................................................ 24

4. UMTS Protocols ....................................................................................................................................... 25

4.1UMTS Related Signalling Protocols .................................................................................................... 25

4.1.1 Medium Access Control (MAC) protocol ....................................................................................... 26

4.1.2 Radio Link Controller protocol ....................................................................................................... 27

4.1.2.1 RLC Transparent Mode (TM) Entity ........................................................................................ 28

4.1.2.2 RLC Unacknowledged Mode Entity ......................................................................................... 29

4.1.2.3 RLC Acknowledged Mode Entity ............................................................................................. 31

4.1.3 Packet Data Convergence Protocol (PDCP) .................................................................................... 32

4.1.4 Broadcast Multicast Control (BMC) ............................................................................................... 33

4.1.5 Radio resource Control (RRC) ........................................................................................................ 34





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4.1.6 RRC States and States Transition including GSM ........................................................................... 35

4.2 ATM and ATM Adaptation Layers ............................................................................................... 37

4.2.1 Asynchronous Transfer Mode (ATM) ........................................................................................ 37

4.2.2 ATM Protocol Architecture ........................................................................................................ 38

4.2.2.1 ATM Adaptation Layer ............................................................................................................ 39

5. Application layer Protocol ....................................................................................................................... 42

5.1 Radio Access Network Application Part (RANAP) ............................................................................ 42

5.1.1 Introduction ............................................................................................................................... 42

5.1.2 Functions of RANAP ................................................................................................................... 43

6. UMTS Protocol Structure ........................................................................................................................ 45

6.1Transport Network Layer ................................................................................................................... 46

6.2 Radio Network layer ......................................................................................................................... 47

6.3 System Network layer ....................................................................................................................... 48

7. OSI Protocol Stack ................................................................................................................................... 49

8. Introduction to GSM .............................................................................................................................. 51

8.1 When Cell is Turned on ..................................................................................................................... 51

8.2 When Cell move from one cell site to another ................................................................................. 53

9. References .............................................................................................................................................. 54





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1. Introduction to UMTS

3G is referred as Universal Mobile Telecommunication system in Europe which is one of the mobile

phone technology.

UMTS is a Standardized by 3GPP and is European answer to the ITU IMT 2000 requirements.

For 3G cellular Radio System UMTS is an evolution of GSM technology UMTS, the 3G successor to GSM which utilizes the W – CDMA air interface and GSM infrastructure so it is called 3GSM.





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1.1 UMTS Network Architecture

1.1.1 Basic Structure of UMTS Network

User Equipment(UE)

Access Network(AN)

Core Network(CN)

Uu Interaface Iu Interaface

ToOther

Networks(e.g.PSTN)

Basic Structure of UMTS Network

User Equipment

The User Equipment is used to access services provided by network.

To connect to a network a UE interfaces with access network using WCDMA air interface which is referred to as Uu interface.

Access Network

Access Network performs functions specific to the radio access technique. Access Network has 2 entities – The Base transceiver station(BTS) that terminates the radio

connection with the UE and a Base Station Controller(BSC) that controls the resources of BTS. BSC interfaces with CN over Iu interface.

Core Network

Core Network performs the core functions of the network which includes mobility management, call control, switching and routing.

It also manages the subscription information of a subscriber and provides services based on the information.





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1.1.2 Architecture Overview

RNC(Radio

Network Contoller)

RNC(Radio

Network Controller)

MSC GMSC

SGSN GGSN

HSS(Home Subscriber

Server)

PSTN

IMS

RadioUu

Iu

UE

UTRAN CN

Node B

Node B

Node B

Node B

Iub

Iub

Iub

Iub

Iur

CS Domain

PS Domain

MSC : Mobile Switching Center

GMSC : Gateway MSC

SGSN : Serving GPRS support Node

GGSN :Serving GPRS Support Node

PSTN :Public Switched telephone Network IMS: IP Multimedia CN Subsystem

UMTS Architecture • UMTS system consists of number of logical network elements connected through open

interfaces or access points. • These elements are grouped into radio access network and the core network. • UTRAN handles all radio related functionality, radio resource and mobility management. • Core Network (CN) is responsible for switching and routing calls and data connections to

external n/w’s .





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1.1.3 User Equipment

MobileTermination(MT)

TerminalEquipment(TE)

User Equipment(UE)

Mobile Equipment(ME)

Structure of User Equipment

UniversalSubscriber

IdentityModule(USIM)

Universal Integrated

Circuit Card(UICC)

The User Equipment (UE) is a device used by user to access services provided by a network.

UE is divided into 2 parts – Mobile Equipment(ME) and Universal Integrated Circuit Card(UICC).

UICC is a smart card that contains an application called USIM. USIM contains the logic required to identify the user. USIM is user dependent part of UE.

USIM interoperates with UMTS Terminal to provide mobile user access to the UMTS services.

USIM Contains the permanent identity of user called IMSI(international Mobile Subscriber Identity), The shared secret key(used for authentication), the user phone book and a host of other information.

ME is user independent part of UE. It contains a slot to hold UICC which is required to access UMTS network.

ME is further divided into 2 parts – Mobile Termination(MT) and Terminal Equipment(TE).

MT is a part of ME that performs a functions like radio transmission termination, authentication and mobility management.

TE component of ME manages the Hardware and end user applications. TE interact with ME via Terminal adaptation (TA) function.

1.1.4 UMTS Radio Access network

UTRAN is subdivided into individual Radio N/w System(RNSs),where each one is controlled by radio network controller(RNC).

Within RNS, the RNC is connected to a set of Node B Elements, each of which can serve one or several cells.

UTRAN is located between two new open interface Uu and Iu.

The Uu interface is a WCDMA radio interface through which UE accesses the fixed part of the system.





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Uu Interface – Uu Interface is a WCDMA radio interface between mobile and Radio access n/w.

RLC

MAC

FDD Mode TDD Mode

PDCP BMC

RRC

Physical Layer

CS Domain PS Domain BC Domain

Control PlaneUser Plane

Uu Interface

L1

L2

L3

The protocol stack has 2 planes – the user plane carries data streams of interest to the user, while control plane carries the n/w’s signaling msgs.

The User plane is divided futher, to distinguish data streams to and from circuit switched, packet switched and broadcast control domains.

The protocol are as follows

Radio Resource Control (RRC) – This is the main signaling protocol in the Uu interface. It defines signaling messages that are exchanged between mobile and radio access n/w.

Broadcast Multicast Control (BMC) – This is an extra interface to the cell broadcast service. It distributes cell Broadcast messages from the n/w and collects them at the mobile.

Packet data convergence protocol (PDCP) –This is an extra interface for packet data. It carries out functions such as header compression of IP packets.

Radio Link control (RLC) – This manages the radio link between mobile and n/w, for example by optionally retransmitting data packets that have not e received correctly.

Medium access control (MAC) – This carries out low level manipulation and control of the physical layer, for example it prioritises the transmission of different data streams from mobile or Node B to ensure that each one has an appropriate data rate.

Physical layer – This carries out the low – level transmission and reception. It has 2 modes of operation, FDD and TDD.





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Iu Interface – Iu interface connects the UTRAN to the CN. The Packet switched data is transmitted through Iu-Ps interface and circuit switched data is transmitted over Iu-cs interface.

Physical layer

Signalling Transport Transport n/w signalling

RANAP

Data Transport

Frame Protocols SABP

Control Plane

CS Domain BC Domain

User PlaneTransport n/w Control Plane

Iu Interface

Radio n/w Layer

Transport n/w layer

Its protocol stack is divided into 2 layers

All UMTS related issues are in the radio n/w layer, while the transport n/w layer contains standard technology used for the underlying transport.

Stack is divided into 3 planes

User Plane handles data streams that eventually reach UE, control plane handles Iu signaling messages and transport n/w control plane manages the underlying transport.

RANAP – Defines the signaling messages exchanged over Iu Interface.

SABP – Defines the data streams used by the cell broadcast service, and the frame protocols define the CS and PS data streams.





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Iur Interface – Iur Interface is the Logical interface enables handling of RRM and eliminates the burden from CN.

Physical layer

Signalling Transport

Transport n/w signalling- Common Channels- Dedicated channels

RNSAP

Data Transport- Common Channels- Dedicated Channels

Frame Protocols- Common Channels - Dedicated Channels

Control PlaneUser PlaneTransport n/w Control Plane

Iur Interface

Radio n/w Layer

Transport n/w layer

Its Protocol Stack is divided into 2 layers

All UMTS related issues are in the radio n/w layer, while the transport n/w layer contains standard technology used for underlying transport.


User plane handles data streams that eventually reach UE, control plane handles Iur signaling messages and transport n/w control plane messages the underlying transport .

RNSAP – Defines the signaling messages exchanged over Iur Interface and frame protocols define data streams.





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Iub Interface – Iub Interface is the Interface between RNC and Base station. The Main task of UTRAN is to create and maintain Radio access bearers for communication between UE and CN.

Physical layer

Signalling Transport

Transport n/w signalling- Common Channels- Dedicated channels

NBAP

Data Transport- Common Channels- Dedicated Channels

Frame Protocols- Common Channels - Dedicated Channels

Control PlaneUser PlaneTransport n/w Control Plane

Iub Interface

Radio n/w Layer

Transport n/w layer

Its protocol stack is divided into 2 layers

All UMTS related issues are in the radio n/w layer, while transport n/w layer contains standard technology used for the underlying transport.


User plane handles data streams that eventually reach UE, control plane handles Iub signaling messages and transport n/w control plane messages the underlying transport.

Node B Application Part (NBAP) – Defines the signaling messages exchanged over Iub interface and Frame protocols defines data streams.





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Node B

Node B is a physical unit for radio transmission reception in cells. Node B connects with UE Via the WCDMA Uu radio interface and with RNC via the Iub asynchronous transfer mode(ATM) Based interface. RNC is where Radio resources are managed Radio Network Controller

Radio Network Controller is the switching and controlling element of the UTRAN located between

Iub and Iu interface. It also has a third interface called Iur for inter RNS connections the RNC interfaces the CN for both packet-switched and circuit-switched services domain and also

terminates the RRC protocol that defines the messages and procedures between mobile and UTRAN.





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2. UMTS Core Network

2.1 Structure of UMTS Core Network

SGSN GGSN

MSC/VLR GMSC

AuC HLR EIR

To Packet Network

ToAccess

Network

PS Domain

CS Domain

To PSTN Network

Core Network

HLR/AuC

SGSN: Serving GPRS Support Node GGSN : Gateway GPRS Support NodeHLR : Home Location Register AuC : Authentication CenterEIR : Equipment Identity Register VLR: Visitor Location Register

MSC : Mobile Switching Center GMSC : Gateway Mobile Switching Center

Structure of Core Network

Core Network Consists of entities that provide support for various network features and services and performs functions like mobility management, call control, switching, session management, routing, authentication and equipment identification.

The UMTS Core Network is divided into 2 domains : the Circuit switched (CS) domain and Packet Switched(PS) domain.





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The CS domain provides services related to voice transfer, the PS domain to those related to data transfer.

Circuit Switched CN

CS Domain refers to set of all CN entities offering a “CS type connection” the entities specific. To CS domain are

MSC – Mobile Switching Center Switch serves ME at its current location for circuit switch services.

MGW – Media Gateway performs actual switching for user data.

GMSC – Gateway MSC serves UMTS where it is connected to ext CS network.

Packet Switched CN

PS domain transports the user information using autonomous concatenation of bits called Packet CN PS domain in UMTS has 2 basic n/w elements.

SGSN – Serving GPRS support node serves ME for packet data.

GGSN – Gateway serving GPRS support node connects to packet switch n/w to internet.





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2.2 IP Multimedia Sub-System

MRFP MRFP

IMS-MGW

MGCF CSCFHSS

P-CSCF UE

BGCF

BGCF CSCF

PSTN

Legacy mobile Signalling N/w’s

IP Multimedia n/w’s

MbMb

Mb Mb Mb

MpMr

Mg

Mj Mi

Cx

Gm

C, DGc,Gr

Go

Mk

MmPSTN

Mw

Mw

PSTN

IM Subsystem

Mn

Mk

The IP Multimedia CN sub-system (IMS) includes the collection of signaling and bearer related network elements.

The IMS introduces three main logical network elements to the existing infrastructure: the Call Session Control Function (CSCF), the Media Gateway Control Function (MGCF) and the Media Gateway (MGW). The Home Subscriber Server (HSS) is also introduced providing user profile information.

Call Session Control Function o The Call Session Control Function (CSCF) is a SIP server that provides/controls multimedia

services for packet-switched IP terminals, both mobile and fixed. o It can act as Proxy CSCF (P-CSCF), Serving CSCF(S-CSCF), Interrogating CSCF (I-CSCF),

Breakout Gateway CF (BGCF) or Multimedia Resource Function (MRF).

Proxy-CSCF o The Proxy-CSCF (P-CSCF) is the first contact point for the UE within the IM CN subsystem

thus always located in the network where the UE resides. o Its address is discovered after or as a part of a successful PDP context activation. o The P-CSCF forwards SIP messages from UE to the specific I-CSCF or to the SIP server (S-

CSCF) acting as a SIP proxy.





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Serving-CSCF o The Serving-CSCF(S-CSCF) is always assigned in the home network. o It acts as a registrar making information available through the location server (HSS) and

subsequently performs the session control services. o As P-CSCF, the S-CSCF can also act as a SIP proxy server.

Interrogating-CSCF o The Interrogating-CSCF (I-CSCF) is mainly the contact point within an operator’s network for

all IMS connections destined to a subscriber of that network operator, or a roaming subscriber currently located within that network operator’s service area.

o As the contact point, it accesses the HSS to resolve the SIP server addresses involved in the session (ICSCF, BGCF or S-CSCF).

o It obtains the S-CSCF linked with the user in the registration procedure and the S-CSCF of the terminating counterpart in the session establishment.

Breakout Gateway Control Function o The Breakout Gateway Control Function (BGCF) selects the network in which PSTN/CS

Domain breakout is to occur forwarding the session signaling to another BGCF if it is a different one.

o Once in the network in which the inter-working with PSTN/CS domain is to occur, it selects a MGCF which is responsible for such inter-working.

o Therefore this logical entity acts as a signaling entity for call/session control.

Multimedia Resource Function o The Multimedia Resource Function (MRF) is split into Multimedia Resource Function

Controller (MRFC) and Multimedia Resource Function Processor (MRFP). o MRFP controls the bearer on the Mb reference point and provides media stream resources

to be controlled by the MRFC.

Media Gateway o The Media Gateway (MGW) terminates bearer channels from a circuit switched network

and media streams from a packet network.

Media Gateway Control Function o The Media Gateway Control Function (MGCF) entity controls the MGW and performs

translation at the call control signaling level between ISUP signaling, used in PSTN, and SIP signaling, used in the UMTS multimedia domain.





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Home Subscriber Server o The Home Subscriber Server (HSS) is the master database for 3G/UMTS Rel5/6 IP users. o It contains the subscription-related information to support the network entities handling the

IP session. o This entity also integrates the Home Location Register (HLR) functionality for both packet

and circuit domain, which is there on considered as a HSS Subset.

SubscriptionInformation

LocationInformation

SGSN GGSN R-SGW CSCF

Gr(MAP-Based)

Gc(MAP-Based)

Cx(IP based Interface)

Mh

HSS(HLR/UMS)





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2.3 Home PLMN

In UMTS the highest level of hierarchy is a public land mobile network (PLMN).

A PLMN is defined as a telecommunications network providing mobile cellular services.

A PLMN is uniquely identified by its PLMN identifier.

MCC(3 digits)

MNC(2/3 digits)

PLMN identifier

MCC: Mobile Country Code MNC: Mobile Network Code

PLMN: Public Land Mobile Network

Structure of PLMN identifier

The PLMN identifier comprises of Mobile Country Code(MCC) and Mobile Network Code(MNC).

The MCC is of 3 digits identifies the country to which the PLMN belongs.

The MNC of 2 or 3 digits identifies a particular PLMN within a country.

2.4 Home Location Register

Home location Register is a large database that permanently stores the data about subscribers.

The HLR maintains subscriber- specific information such as MSISDN, IMSI, current location of the Mobile station, roaming restrictions and subscriber supplement features.

There is a logically only one HLR in any given n/w, but generally speaking each n/w has multiple physical HLRs spread out across its n/w.





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2.5 Authentication Center (AuC)

VLR

MSC

AuC

EIR

HLR

Authentication Center(AuC)

Authentication Center holds Authentication Information .

This information is used for authentication and security related functions.

It is often depicted as a part of HLR.

Thus the term AuC/HLR is used to represent the entity that performs the functions of HLR and AuC.

The Interface between HLR and AuC is called H interface.

2.6 Equipment Identity Register(EIR)

VLR

MSC

EIR

HLR

Equipment Identity Register(EIR)

MSC

VLR

F Interface

B InterfaceD Interface

Equipment Identity Register(EIR) is a database that keeps tracks of handsets on the n/w using International Mobile Equipment Identity(IMEI).

The IMEI is used for identifying a user equipment.

There is only one EIR per n/w. It is composed of 3 lists.





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Black List – Is a list if IMEIs that are to be denied service by the n/w for some reason. Reasons include IMEI if handset is malfunctioning or doesn’t have the technical capabilities to operate on n/w.

Grey List – Is a list of IMEIs that are to be monitored for suspicious activity. This could include handsets that are behaving oddly or not performing as the n/w expects it to.

White List – Is an Unpopulated list. That means if an IMEI is not on the black list or on the grey list then it is considered good and is “on the white list”.

2.7 Mobile Switching Center

Mobile Switching Center is a heart of a network.

It handles call routing, call setup, and basic switching functions.

MSC is a node that interfaces between the Access network and the Core network.

It performs all functions necessary to handle the circuit switched services.

2.8 Visitor Location Register(VLR)

Visitor Location Register is a database that contains a subset of information located on HLR.

It contains a similar information as HLR, but only for subscribers currently in its location area.

There is VLR for every location area.

The VLR reduces the overall number of queries to HLR and thus reduces n/w traffic.

VLRs are often identified by location Area Code(LAC) for area they service.

2.9 Gateway Mobile Switching center (GMSC)

The Gateway MSC functions as a gateway between two n/w’s.

If a mobile subscriber wants to place a call to a regular land line, then call would have to go through a Gs GMSC order to switch to (PSTN).

It also provides the means for an incoming call to be delivered to the MSC where the MS is registered.

Eg – If a subscriber in a circular n/w wants to call a subscriber on T – mobile n/w, the call would have to go through GMSC.





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3. UMTS N/w Transaction

Node B RNC MSC SGSN

RRC Connection Setup

Iub Bearer Establishment

Transaction Reasoning

Authentication Security Control

Iu-CS/ PS Bearer EstablishmentRadio Bearer Establishment

End – to – End Connection

Iu -CS/PS Bearer Release

Iub Bearer Release

Clearing of RRC Connection

The procedures running between UE, Node B and RNC will exchange Access – Stratum messages

Whereas procedures going through to the CN, MSC,SGSN will exchange NON Access Stratum messages





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3.1 Iub – Node B Setup

Node B RNC

RACH

FACH

PCH

ATM STM - 1 Line

a b

c d

a b

c d

Common Transport Channels

ATM Virtual Path

(VPI =x)

Before Node B setup

After Node B setup

PCH:CID =8

FACH:CID =9

RACH :CID =10

ATM Virtual Chann

els

VCI =a->NBAPVCI =b->ALCAP

VCI =c,d->Reserved for AAL2

Node B setup against a RNC

Step 1 – The Node B requests to be audited by the RNC. During the audit, Node B informs the RNC of

How many cells belongs to Node B and which local cell identifiers they have.

Step 2 – For each cell, the RNC performs a cell setup. During cell setup, the physical(radio interface)

Channels are parameterized. These channels are mandatory in case of a UE initial access. In other words

If there channels are not available it is impossible for UE after it is switched on to get access to the n/w

Via the radio interface.

Step 3 – The common transport channel paging channel PCH, forward Access Channel and Random

access channel are setup and optionally parameterized in each cell of new Node B. On the Iub interface

There common transport channels are carried by AAL2 connections on ATM lines. ATM/AAL2 header

Values (VPI/VCI/CID) are important because without knowing them it is impossible to monitoring

Signaling and data transport on PCH,RACH and FACH. If there channels are monitored some of the most

Important message for call setup and mobility management procedures, such as paging messages and

RRC connection setup will be missed call traces. Once the AAL2 connection for a communication

Transport is installed during Node B setup it will not be released until Node B is taken Out of service.





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3.2 Message Flow

Node B RNC

NBAP UL initiating Message Id- audit required

NBAP DL initiating Message Id- audit start of audit

NBAP UL Successful Outcome id – audit, end of audit sequence”(Local cell -ids)

Opt. FP up – and Downlink Node sync(PCH between Node B and RNC)

NBAP UL successful Outcome id – cell setup

NBAP DL initiating Msg id – system information update(SiBs)

NBAP DL initiating Msg id – common transport channel setupCell-Id,ctrch -id+PCH TFS)

NBAP UL successful outcome id – common Transport channel setup(cTrcH-ID, bind ID =h)

NBAP DL initiating message id -cell setup (Cell-id, primary scrambling code, common physical channel IDs

ALCAP DL ERQ(Path-ID, Ch-ID, SUGR=h)

ALCAP UL ECF





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3.3 Iub – Iu – Loaction Update

RNC MSC

1) Setup DCCH/RRC Connection

2) DCCH/RRC Connection

LURECLUACC or LUREJ

3) SCCP/RANAP connection

5) DCCH/RCC Release4) SCCP/RANAP Release

SCCP CR(RANAP IM LUREQ)

LUACC or LUREJ

Step 1 – Set up the dedicated control channel (DCCH) for the RRC connection on the Iub interface.

Step 2 – MM/CC/SM(Mobility Management/ Call Control/Session Management) msgs are

transparently forwarded to the RNC on behalf of RRC direct transfer msgs in this case the location

Update request (LUREQ) msg.

Step 3 – The reception of the LUREQ message triggers the setup of a SCCP/RANAP connection

on the Iu-CS interface towards MSC/VLR. The LUREQ is embedded in a SCCP connection Request

The answer can be either location update accept (LUACC) or location update reject(LUREJ).

Step 4 – After tending the answer msg, the SCCP/RANAP connection on Iu-CS is released.

Step 5 – Triggered by the release messages from the Iu – CS the RRC connection and its DCCH

are also released.





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4. UMTS Protocols

4.1UMTS Related Signalling Protocols Access Stratum and Non Access Stratum protocols

RLC

MAC

Physical Layer

RRC

PDCPBMC

MM/GMM

CC SM SS SMSUser Plane Protocols

(eg.IP)

Control

Control Plane

Non – AccessStratum

Access Stratum

Structure of Access Stratum and Non access Stratum

Access Stratum are the protocols used on the radio interface between UE and UTRAN.

These protocols are used for the transfer of user and control data between UE and UTRAN.

The Access stratum protocols of UE are implemented in Radio termination (RT) component of Mobile Termination (MT).

These protocols include the following

Physical Layer – The Physical Layer is the lower-most layer of the UMTS radio interface stack. It is the layer that is responsible for actual transmission of higher layer data over the Physical.





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4.1.1 Medium Access Control (MAC) protocol

Medium Access Control (MAC) protocol - Medium Access Control (MAC) Layer is the lowest sub –layer of layer 2 of the protocol stack. The MAC communicates with the physical layer using the transport channels. The Main functionality of MAC layer is to map higher layer data on to appropriate transport channels of the physical layer.

MAC-bMAC – c/sh

MAC - d

BCCH PCCH BCCH CCCH CTCH DCCH DTCHMAC-

Control

BCH PCH FACH RACH CPCH DSCH DCH DCH

TransportChannels

LogicalChannels

MAC Layer Logical Architecture

MAC –b – This controls access to the Broadcast channel (BCH).

MAC –c/sh – It controls access to the common and shared channels.

MAC – d – The MAC –d control access to the Dedicated Channel (DCH).

MAC PDU Format

TCTF UE -IdType

UE-Id C/T MAC - SDU

MAC PDU

MAC Header MAC SDU

MAC Header Consists of

Target Channel Type Field (TCTF) – a flag that provides identification of logical channel class on FACH and RACH transport channels.





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C/T field – provides identification of the logicalk channels instance when multiple logical channels are carried on the same transport channels.

UE – id field – provides an identifier of UE on common transport channels.

UTRAN Radio N/w Temporary identity(U-RNTI) may be used in MAC header of DCCH when mapped onto common transport channels in downlink directions the U-RNTI is never used in uplink directions.

Cell Radio N/w Temporary Identity(C-RNTI) is used on DTCH and DCCCH in uplink, and may be used in DCCH in downlink and is used on DTCH in downlink when mapped onto common transport channels.

UE-Id to be used by MAC is configured through MAC control SAP.

UE-Id type field –is needed to ensure correct decoding of UE-Id field in MAC headers.

4.1.2 Radio Link Controller protocol

TransmittingTransparent

Entity

ReceivingTransparent

Entitiy

AcknowledgedModeEntity

Transmitting Unacknowledged

Entity

ReceivingUnacknowledged

Entity

RLC Control

Tr - SAP

BCCH/PCCH/CCCH/DCCH/DTCH DTCH/DCCH

AM - SAP UM - SAP

CCCH/CTCH/DTCH/DCCH

RLC Logical Architecture

Provides Segmentation/reassembly(payload units,PU) and retransmission service for both users and control data.

Transparent Mode (Tr) : no overhead is added to higher layer data.

Unacknowledged Mode (UM) : no retransmission protocol is used and data delivery is not guaranteed.

Acknowledged Mode (AM) – Automatic Repeat request (ARQ) m echanism is used for error correction.





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4.1.2.1 RLC Transparent Mode (TM) Entity

Radio Interface(Uu)

Transmissionbuffer

Segmentation

Reassembly

Reception Buffer

UE/UTRAN UTRAN/UE

TM-SAP TM-SAP

CCCH/DCCH/DTCH/SHCCH – UEBCCH/PCCH/DCCH/DTCH - UTRAN

CCCH/DCCH/DTCH/SHCCH – UTRANBCCH/PCCH/DCCH/DTCH - UE

Transmitting

TM-RLCEntity

ReceivingTM-RLC

Entity

RLC Transparent Mode Entity

Receiving TM-RLC Entity

The Receiving TM-RLC entity receives TMD PDUs through the configured logical channels from the lower layer.

If segmentation is configured by upper layer all TMD PDUs received within 1 TTI are reassembled to form the RLC SDU.

If segmentation is not configured by upper layers, each TMD PDUs is treated as a RLC SDU.

The receiving TM RLC entity delivers RLC SDUs to upper layers through the TM-SAP. Transmitting TM –RLC Entity

Transmitting TM-RLC entity receives RLC SDUs from upper layers through the TM – SAP.

All received RLC SDUs must be of a length that is multiple of one of the valid TMD PDUs lengths.

If segmentation has been configured by upper layers and a RLC SDU is larger than the TMD PDU size used by the lower layer for that TTI, the transmitting TM RLC entity segments RLC SDus to fit the TMD PDUs size without adding RLC headers.All the TMD PDUs carrying one RLC SDU are sent in the same TTI, and no segment from another RLC SDU are sent in this TTI.

If segmentation has not been configured by upper layers then more than one RLC SDU can be sent in one TTI by placing one RLC SDU in one TMD PDU . All TMD PDUs in one TTI must be of equal length.

When the processing of a RLC SDU is complete the resulting one or more TMD PDUs are is submitted to the lower layer through either a BCCH, DCCH, PCCH, CCCH, SHCCH or a DTCH logical channels.





M2M COMMUNICATIONS


4.1.2.2 RLC Unacknowledged Mode Entity

Radio Interface(Uu)

Transmissionbuffer

Segmentation &Concatenation

Reassembly

Removal RLC Header

UE/UTRAN UTRAN/UE

UM-SAP UM-SAP

CCH/DTCH – UECCH/SHCCH/DCCH/DTCH/CTCH - UTRAN

Transmitting

UM-RLCEntity

ReceivingUM-RLC

Entity

RLC Unacknowledged Mode Entity

Add RLC Header

Ciphering

Reception Buffer

Deciphering

DCCH/DTCH – UTRANCCCH/SHCCH/DCCH/DTCH/CTCH - UE





M2M COMMUNICATIONS


Receiving UM-RLC entity

The Receiving UM-RLC entity receives UMD PDUs through the configured logical channels from lower layer.

The Receiving UM RLC entity deciphers(if ciphering is configured and started) the received UMD PDUs. It removes RLC headers from received UMD PDUs and reassembles RLC SDUs.

RLC SDUs are delivered by the receiving UM RLC entity to the upper layers through the UM-SAP. Transmitting UM-RLC entity

Transmitting UM-RLC entity RLC SDUs from upper layers through the UM-SAP.

The transmitting UM-RLC entity segments the RLC SDU into UMD PDUs of appropriate size if the RLC SDU is larger than the length of available space in the UMD PDU. The UMD PDU may contain segmented and/or concatenated RLC SDUs. UMD PDU may also contain padding to ensure that it is of a valid length. Length Indicators are used to define boundaries between RLC SDUs within UMD PDUs length indicators are also used to define whether padding is included in the UMD PDU.

If Ciphering is configured and started an UMD PDU is ciphered before it is submitted to the lower layer.

The transmitted UM-RLC entity submits UMD PDUs to the lower layer through either a CCCH,SHCCH,DCCH,CTCH or a DTCH logical channel.





M2M COMMUNICATIONS


4.1.2.3 RLC Acknowledged Mode Entity

Segmentation and concatenation

Add RLC Header

Retx. Buffer and management

Transmission Buffer

Set fields in PDU header (eg set poll bits) and piggybacked STATUS PDU

Ciphering

RLC Control Unit

Reassembly

Remove RLC Header and extract piggybacked info

Reception buffer and management

De-Ciphering

Demux/Routing

MUX

Piggy Backed status

Acks

Acks

AM entity

RLC

MAC

RRC/BMC/PDCP/..

RLC Acknowledged Mode Entity

The Receiving side of the AM-RLC entity receives AMD and control PDUs through the configured logical channels from the lower layer.

AMD PDUs are routed to the deciphering unit and then delivered to the reception buffer.

The AMD PDUs are placed in the reception buffer until a complete RLC SDU has been received. The receiver acknowledges successful reception or requests retransmission of the missing AMD PDUs by sending one or more STATUS PDUs to the AM RLC peer entity through its transmitting side.

The associated AMD PDUs are reassembled by the reassembly unit and delivered to the upper layers through the AM-SAP.

RESET and RESET ACK PDUs are delivered to the RLC control unit for processing. If a response to the peer AM RLC entity is needed an appropriate control PDU is delivered by the RLC control unit to the transmitting side of the AM RLC entity. The transmitting side of the AM-RLC entity receives RLC SDUs from upper layers through the AM-SAP.

RLC SDUs are segmented and/or concatenated into AMD PDUs of a fixed length. o The segmentation is performed if the received RLC SDU is larger than the length of available

space in the AMD PDU. o The PDU size is set during AM-RLC establishment. o The packets could be segmented, concatenated, padded. o Boundaries between the packets are indicated by a length indicator.

After segmentation and/or concatenation are performed the AMD PDUs are placed in the retransmission buffer at the MUX.

AMD PDUs buffered in the retransmission buffer are deleted or retransmitted.





M2M COMMUNICATIONS


The MUX multiplexes AMD PDUs from the Retransmission buffer that need to be retransmitted and the newly generated AMD PDUs delivered from the segmentation/concatenation function.

The PDUs are delivered to the function that completes the AMD PDU header and potentially replaces padding with piggybacked status information . A Piggy backed STATUS PDUs can be of variable size in order to match the amount of free space in the AMD PDU.

The ciphering (if configured) is then applied to the AMD PDUs. o The AMD PDU header is not ciphered. o Control PDUs(i.e STATUS PDU, RESET PDU and RESET ACK PDU) are not ciphered.

4.1.3 Packet Data Convergence Protocol (PDCP)

The Packet Data Convergence protocol (PDCP) layer is used to carry user plane information for the PS domain.

PDCP carries data protocols like IP and PPP.

PDCP

RLC

Control(RRC)

PDCP SAPs

Radio Bearers(User Plane Information)

PDCP Layer Architecture

UM AM TM

PCDP Architecture provides means to transfer user plane information using one of the modes of RLC

layer (TM, UM or AM).

The RRC layer controls the behaviour of the PDCP layer.





M2M COMMUNICATIONS


4.1.4 Broadcast Multicast Control (BMC)

BMC Entity

BMC SAP

UM - SAP

RLC SAPs

BMC - Control

BMC Layer Architecture

The Broadcast Multicast Control (BMC) layer is used to carry user plane information in the downlink

direction.

Storage of cell broadcast messages.

Traffic volume monitoring and radio resource request for CBS.

Scheduling of BMC messages.

Transmission of BMC messages to UE.

Delivery of cell broadcast messages to upper layer.





M2M COMMUNICATIONS


4.1.5 Radio resource Control (RRC)

Used for setting up, reconfigured and reestablish radio bearers.

DCFEPNFE BCFE

Message Routing

AM-SAP AM-SAPAM-SAP UM-SAP Tr-SAP

BMC-Control

SAP

PDCP-Control

SAP

RLC-Control

SAP

MAC-Control

SAP

I1-Control

SAP

RLC SAPs

RLC Logical Structure

Dedicated Control Functional Entity (DCFE) – Handler functions and signaling specific to UE one DCFE entity for each UE.

Paging and Notification control functional Entity (PNFE) – Paging of idle mode UE. At least one PNFE in the RNC for each cell.

Broadcasting Control functional Entity (BCFE) – Handles the Broadcasting of system information. There is at least one BCFE for each cell in the RNC.





M2M COMMUNICATIONS


4.1.6 RRC States and States Transition including GSM

CELL_DCH

GSM Connected Mode

GPRS Packet Transfer Mode

Out of Servic

e

In service

Out of servic

e

In Servic

e

Out of Servic

e

In servic

e

URA_PCH CELL_PCH

UTRA RRC Connected Mode

CELL_FACH

Release RRC Connection

Establish RRC Connection

Release RRC Connection

Establish RRC Connection

UTRA Inter – RAT Handover

GSM Handover

Camping on a UTRAN cell

Idle Mode

GPRS Packet Idle Mode

Camping on a GSM/GPRS Cell

Call Reselection

Release of temporary block flow

Initiation of temporary block flow

Release RR Connection

Establish RR Connection

RRC States and States Transitions Including GSM

Idle Mode – o After UE in Switched on it will camp in a suitable cell. After Camping. o User is able to send and receive system and cell broadcasting information. o In the idle mode until it transmits request to establish RRC connection.

Cell_DCH o Entered from Idle Mode or by establishing a DCH from the cell_FACH state. o DPCH and physical downlink shared channel(PDSCH) is allowed to UE. o UE is in this mode until explicit signalling for Cell_FACH.

Cell_FACH o No dedicated channel allocated. Data transmitted through RACH and FACH. o UE listens BCH. o Cell reselection is performed (RNC is informed).





M2M COMMUNICATIONS


Cell_PCH o UE known at a cell level but can be reached via PCH. o Usel listens BCH, some terminals also BMC. o In case of Cell reselection automatically moved to Cell_FACH state.

URA_PCH o UE executes the cell update procedure only if the UTRAN Registration Area is changed. o DCCH cannot be used in this state, all the activities initiated by the network through the

PCCH or RACH.





M2M COMMUNICATIONS


4.2 ATM and ATM Adaptation Layers

4.2.1 Asynchronous Transfer Mode (ATM)

Asynchronous transfer Mode (ATM) is defined as a transfer mode in which the information is

organized into cells.

Transfer Mode – o Transfer Mode is used to transmit, switch and multiplex information. Transfer mode is

means of packaging, sending and receiving information on the n/w.

o Circuit switching and packet switching describe the two extremities of transfer mode. o In circuit switching it is sent in bit streams, while in packet switching the information is sent

as large frames.

Asynchronous Name – o ATM is Asynchronous in the sense that the recurrence of cells containing information is not

periodic. o The terms Synchronous and Asynchronous refer to the way the data is transmitted. o In the synchronous mode, the transmitter and receiver clocks are synchronized and frames

are sent/received periodically. o In asynchronous mode, timing information is derived from the data itself and the

transmitter is not compelled to send data periodically.

Cell –based transfer – o The Information in ATM is ‘organized into cells’, which means that lowest unit of

information in ATM is a cell. o A cell is fixed size frame of 53 bytes, with 5 bytes of header and 48 bytes of payload. o The header carries the information which is required to switch cells, while payload contains

the actual information to be exchanged.





M2M COMMUNICATIONS


4.2.2 ATM Protocol Architecture

Physical Layer

ATM Layer

ATM Adaptation Layer

Control plane User plane

Layer M

anage

me

nt

Plan

e M

anage

me

nt

Management Plane

ATM Protocol Architecture

Higher layers(ALCAP and SAAL)

Higher Layers(e.g. TCP/IP)

It is a 3 – dimensional model

User Plane – o The User Plane is concerned with the transfer of user information. o At transmitting side the plane is responsible for packing user information into cells and

transmitting cells using underlying physical medium. o At receiving side, it performs reverse operation and derives the higher layer information.

Control Plane – o The control plane is responsible for establishing and releasing connection between a given

source and destination. o When a new connection is established, the control plane establishes a mapping at the

intermediate switches between incoming VPI/VCI and outgoing VPI/VCI. o When a same connection is released, the control plane removes the mapping stored within

the intermediate nodes.

Management Plane – o It is responsible for mapping the individual layers in the protocol stack and providing

coordination between the layers. o It is divided into layer management and plane management. o Layer Management – Layer management is responsible for managing each of the layers,

including their administration, management and configuration. o Plane Management – Plane Management is responsible for coordination among different

planes.





M2M COMMUNICATIONS


4.2.2.1 ATM Adaptation Layer

ATM Adaptation Layer (AAL) allows existing n/w’s to connect to ATM facilities.

ATM Adaptation Layer resides over the ATM Layer.

It is responsible for handling different types of data and mapping the requirements of the applications to the services provided by the lower layer.

The AAL2 and AAL5 is used in UTRAN.

ATM Adaptation Layer (AAL2)

AAL2 resides over ATM layer.

Common Part Sublayer

Service Specific Convergence Sublayer (SSCS)(May be Null)

Upper Layers

AAL 2

Lower Layers

Structure of AAL2

AAL 2 Layer architecture is divided into 2 parts Common Part Sublayer (CPS) and Service Specific Convergence Sublayer (SSCS).

CPS provides the basic functionality of AAL2 which includes the packaging the variable payload into cells and providing error correction.

SSCS sublayer directly interacts with the user. This Layer is used to enhance the services provided by CPS.





M2M COMMUNICATIONS


Segmentation and reassembly functions of service specific convergence sublayer is divided into 3 parts.

Service Specific Segmentation and Reassembly Sublayerv(SSSAR) –This is the Basic function of SAR SSCS. It includes data transfer of SSSAR – SDUs of up to 65568 octets.

Service Specific Transmission Error Detection Sublayer (SSTED) - The Role of SSTED is to detect corrupted SSTED – SDUs.

Service Specific Assured Data Transfer Sublayer (SSADT) – To provide support for retransmission, the SSADT function may be used over and above the SSSAR and SSTED function.

ATM Adaptation layer 5 (AAL5)

Common Part Convergence Sublayer (CPCS)

Service Specific Convergence Sublayer (SSCS)(May be Null)

Upper Layers

AAL5

ATM

Structure of AAL5

Segmentation and Reassembly (SAR)

Convergence Sublayer

Common Part

The AAL5 Layer is divided into 2 Sublayers convergence Sublayer (CS) and the Segmentation and Reassembly Sublayer (SAR).

The CS itself is divided into 2 parts Common part Convergence Sublayer (CPCS) and Service Specific Convergence Sublayer (SSCS).

Segmentation and Reassembly (SAR) – o The segmentation and reassembly sublayer in AAL5 is very simple. o This layer does not add any header or trailer to the SAR – SDU. o It just breaks down the SAR – SDU into 48 bytes SAR –PDUs, which in turn form payload of

the cells.

Common Part Convergence Sublayer (CPCS) – o The CPCS of AAL5 provides 2 modes of data transfer, namely message mode and the

streaming mode.





M2M COMMUNICATIONS


o In message mode of data transfer an entire CPCS – SDU is received from the upper layer and only then transferred to the SAR Sublayer.

o In streaming mode allows the CPCS to start transferring data before it has received the complete CPCS – SDU from upper layer.





M2M COMMUNICATIONS


5. Application layer Protocol

5.1 Radio Access Network Application Part (RANAP)

5.1.1 Introduction

The Iu Interface connects RAN to core n/w.

The Radio Access n/w application part (RANAP) protocol is used over the Iu interface.

RANAP carries Non Access Stratum (NAS) messages, which are relayed between CN nodes and the Ues.

Iu interface is divided into 2 instances o The Iu Circuit switched (CS) to connect RAN to the MSC server. o The Iu Packet Switched (PS) to connect to the SGSN.

The Iu Interface is divided into o A Control plane o A User plane

RRC RANAP

RadioInterfaceprotocols

Iu transport (Signalling Bearers)

Radio Resource Management (RRM)

RRC Messages

ToMS

RNC

RANAP Messages

To Core Network

UuInterface

Iu Interface

Layer Architecture for RANAP





M2M COMMUNICATIONS


Node B RNC

MGW

SGSN

MSC/VLR

RANAP Signalling Over the Iu Interface

NAS Messages

NAS Messages

Uu

Iub

RANAP

RANAP

Iu UP

Iu UP

5.1.2 Functions of RANAP

RANAP supports functionalities that are implemented by various RANAP Elementary procedures (EPs) each function may require the execution of one or more EPs.

Three Kinds of EPs are used o Class 1 – EPs with response (success and/or failure) o Class 2 – Eps without response o Class 3 – EPs with possibility of multiple responses.

RANAP has following functions o Paging

This function provides the CN for capability to page the UE. o Common ID management

IMSI of the UE is sent from CN to RAN. o Transport of NAS information between UE and CN

provides transparent transfer of UE and CN signaling messages that are not interpreted by RAN.

o Security Mode Control Used to send the security users and algo.(ciphering and integrity protection) to RAN

and setting the operation mode for security functions. o Radio Access Bearers (RAB) management

Responsible for setting up, modifying and releasing RABs.





M2M COMMUNICATIONS


o In Release Releases all resources (control and user plane) from a given instance of Iu related to

the specified UE. o Relocating serving RNC (SRNC)

Handles both SRNS relocation and hard handover. In SRNC relocation the serving radio n/w subsystems (RNS) functionality is relocated

from 1 RNS to another without changing the radio resources and without interrupting the user data flow only when all radio links are already in the same DRNC that is target for the relocation.

o Management of Overload Controls the overload of Iu Interface.

o Reset Used to reset Iu Interface in error situations.

o Location Reporting Allows the CN to receive information on the location of given UE.

o Data volume reporting Responsible for reporting unsuccessful transmitted data.





M2M COMMUNICATIONS


6. UMTS Protocol Structure

Transport Network Layer

Radio Network Layer

System Network Layer

User Plane

Control Plane

User Plane

Control Plane

User Plane

Control Plane

UE Node RNC SGSN GGSN

Transport Network Layer o Responsible for providing the general – purpose transport services for all UMTS network

elements across the interfaces.

Radio Network Layer o It is on Top of Generic transport network protocol.

System Network Layer o It operates on top of Radio Network. o It creates the communication service to the users of those terminals.





M2M COMMUNICATIONS


6.1Transport Network Layer

WCDMA L1

MAC

RLC

RRC/PDCP

WCDMAL1

Transport

FP

RLC

MAC

FP

Transport

Transport

Layers

RRC/PDCP

RANAP/IuFP

RANAPIuFP

Transport

Layers

UE Node B SRNC CN

L1

L2

Uu IuB Iu

RadioInterface Terrestrial Interface

Transport Network layer

It is the Lowest Layer of UMTS protocol architecture which provides facilities to transport and route both control and user traffic across all UMTS network interfaces.

It is divided into two protocol layers physical layer (L1) and Data link layer (L2).

W-CDMA Physical Layer o Physical layer of UMTS radio interface is based on W – CDMA radio technology and

terrestrial interfaces are typically based on digital transmission technology such as ATM.

Uu Interface o Uu Interface L2 is defined into MAC and RLC. o MAC is responsible for mapping logical channels. o RLC provides segmentation/reassembly of variable length higher layer protocol PDUs into

smaller RLC Payload Units Pus.

Terrestrial Interface o It uses 2 protocols ATM protocol and TCP/UDP/IP protocol. o These are non specific UMTS protocols introduced in stack with adaptation protocols AAL,

for ATM and GPRS tunneling GTP in IP.





M2M COMMUNICATIONS


6.2 Radio Network layer

RRC NBAP NBAP RNSAPRNSAP

RRCRANAP

RANAP

Uu Iub Iur Iu

UE Node B DRNC SRNC CN

Radio Network Layer

It is Top of generic transport network protocol.

It extends from UE across the access network UTRAN and terminates at the edge nodes of CN.

Radio Network Control Plane o Radio Resource Control (RRC) protocol operates between UE and RNC. o The Main function of RRC protocol is to control radio bearers for user plane traffic RRM

using the signaling radio bearers. o Radio Access Network Application Part (RANAP) allows CN domain to access Services

provided by UTRAN. o It handles the control of the resources between RNC and the Core Network. o It is located at the top of Iu signaling transport layer. o RASAP maintain control plane signaling across UTRAN Iub and Iur Interfaces.

Radio Network Plane o It is used to transfer data along the radio access bearers established by control plane.





M2M COMMUNICATIONS


6.3 System Network layer

Signalling Connection

GPRS MM GPRS MM

SS SMS SM SS SMS SM

Uu Iu

UE RNC SGSN

Session

MM Content

System Network layer

It operate on Top of radio network through non access stratum and UMTS CN.

Non Access Stratum refers to group of control plane protocols which controls the communication between UEs and CN.

MM – Operates over signaling connection provided by radio network. On top of MM sublayer the service specific communication management (CM) protocols operate session management (SM) supplementary service (SS) and GPRS short message service GSMS for PS CN domain.





M2M COMMUNICATIONS


7. OSI Protocol Stack

Physical Layer

Data Link Layer

Network layer

Transport layer

Session Layer

Presentation Layer

Application Layer

Application Layer o The Application Layer is the end-user interface to the OSI system. o It is where the applications, such as electronic mail, USENET news readers, or database

display modules reside. o The application layer’s task is to display received information and send the user’s new data

to the lower layers. o In distributed applications, such as client/server systems, the application layer is where the

client application resides. o It communicates through the lower layers to the server.

Presentation Layer o The presentation layer’s task is to isolate the lower layers from the application’s data

format. o It converts the data from the application into a common format, often called the canonical

representation. o The presentation layer processes machine-dependent data from the application layer into a

machine-independent format for the lower layers machine has instructions for if data comes in without reformatting instructions, the information might not be assembled in the correct manner for the user’s application.

Session Layer o The Session Layer organizes and synchronizes the exchange of data between application

processes. o It works with the application layer to provide simple data sets called synchronization points

that let an application know how the transmission and reception of data are progressing. o In simplified terms, the session layer can be thought of as a timing and flow control layer.





M2M COMMUNICATIONS


Transport Layer o The Transport layer, as its name suggest, is designed to provide the “transparent transfer of

data from a source end open system to a destination end open system, ”according to the OSI reference model.

o The Transport layer establishes, maintains, and terminates communications between two machines.

o The Transport layer is responsible for ensuring that data sent matches the data received. o This verification role is important in ensuring that data is correctly sent, with a resend if an

error was detected. o The Transport layer manages the sending of data.

Network Layer o The network layer provides the physical routing of the data, determining the path between

the machines. o The network layer handles all these routing issues, relieving the higher layers from this

issue. o The network layer examines the network topology to determine the best route to send a

message as well as figuring out relay streams. o It is the only network layer that sends a message from source to target machine, managing

other chunks of data that pass through the system on their way to another machine.

Data Link Layer o The data link layer, according to the OSI reference paper, “provides for the control of the

physical layer, and detects and possibly corrects errors that can occur.

Physical Layer o The Physical layer is the lowest layer of the OSI model and deals with the “mechanical,

electrical, functional, and procedural means ”required for transmission of data, according to the OSI definition.





M2M COMMUNICATIONS


8. Introduction to GSM 8.1 When Cell is Turned on

Power OnScan Channels,

Monitor RF levelsSelect Channel With Highest RF level

Among Control Channels

Scan Channel for Frequency correctBurst (FCCH)

Select Channel with next highest RF level From control list

IS FCCH Detected?

Scan Channel for timing SynchronizationBurst (SCH)

Is SCH Detected?

Read data from BCCH channel and determine the channel is a control

Channel (BCCH)

Is the correct BCCH info

Camp on BCCH and start Decoding

From the Channel data Update the Control channel list

No

Yes

Yes

No

No

Yes





M2M COMMUNICATIONS


When Cell First turns on, it searches all 124 channels in the downlink for signals.

It will then order the channels by received signal strengths and check to determine if the channel was a BCH (Broadcast Channel).

Once Mobile station finds a BCH it adjusts internal frequency and timing for frequency correction channel (FCH) and synchronization channel (SCH) then checks to determine if the BCH is from its public land mobile network (PLMN).

This involves comparing the allowed n/w and country codes stored on the SIM card with the information encoded of BCCH.

The Mobile repeats this cycle until a good broadcast channel is found.

If the mobile recognizes that its in a difference cell from last time it was used it needs to tell the network where it is.

The n/w has to keep track of where every mobile is so that it can route calls to correct cell for the particular mobile this process is called location update.

Once the Mobile has synchronized to the base station.

Determine that its allowed to use the n/w land if a necessary done a location update its compared once camped the mobile is ready to send and receive calls.





M2M COMMUNICATIONS


8.2 When Cell move from one cell site to another

BTSBTS

BTS

RNC MSC

HLR

Public N/w

Mobile Phone

Mobile Phone

Within The Range Of Service area

Controlling The BTS

Switching Center

Cell

Controlling MobilePhone Location Information

BTS : Base Transceiver StationMSC: Mobile Switching Center

RNC : Radio N/w ControllerHLR : Home Location Resister

Service area is achieved by installing wireless BTS , which receive radio signals from mobile phone in numerous locations.

The range within which radio s/g’s from mobile phones can reach a BTS is referred to as a cell.

Even if mobile phone moves from 1 cell to another the call is handoff to the BTS that controls the next cell (handoff function) so that it can be continued without interruption BTS convert the radio s/g’s received from mobile phones to asynchronous transfer mode (ATM) protocol and then send them to a radio n/w controller that controls multiple BTS.

These s/g’s pass through a mobile services switching center(MSC) which controls mobile phone connections and various services and are then sent to an existing public telephone n/w.





M2M COMMUNICATIONS


9. References

3GPP TS 21.103 3rd Generation Mobile System Release 5 Specifications

3GPP TS 25.401 UTRAN Overall Description

3GPP TS 23.002 Network Architecture

3GPP TS 23.101 General UMTS Architecture

3GPP TS 25.301 Radio Interface Protocol Architecture

3GPP TS 25.331 Radio Resource Control (RRC) Protocol Specification

3GPP TS 23.228 IP Multimedia Subsystem

www.3gpp.org

www.3gpp2.org

www.itu.int

www.etsi.org

http://www.3gpp.org/

http://www.3gpp2.org/

http://www.itu.int/

http://www.etsi.org/

3g message flow

Documents