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GPRS WELCOME TO THE WORLD OF INTERNETUnit – 3

Vipul joshi

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CONTENTS OF PRESENTATION

A) GPRS and packet data network,B) GPRS network architecture, C) GPRS network operation, D) Data services in GPRS, E) Applications of GPRS, F) Billing and charging in GPRS

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“ GPRS “

GPRS- General Packet Radio Service provides a direct link into the Internet from a GSM phone

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INTRODUCTION TO GPRS

GPRS will undoubtedly speed up a handset's Internet connection - but it remains to be seen exactly how much speed can be achieved out of the system

GPRS works by aggregating a number of separate data channels. This is possible because data is being broken down into small 'packets' which are re-assembled by the receiving handset back into their original format.

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INTRODUCTION (CONT…)

GPRS stands for General Packet Radio Service , and is a relatively low cost technology that offers packet-based radio service and allows data or information to be sent and received across mobile telephone networks.

GPRS provides a permanent connection where information can be sent or received immediately as the need arises, subject to radio coverage.

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CONSTRAINTS WITH EXISTING NETWORK

• Data Rates too slow – about 9.6 kbps• Connection setup time too long • Inefficient resource utilization for bursty

traffic• Proves expensive for bursty traffic

utilization• No efficient method for packet transfers

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COMPARISON OF GSM & GPRS

GSM GPRSData Rates 9.6 Kbps 14.4 to 115.2

KbpsModulation Technique

GMSK GMSK

Billing Duration of connection

Amount of data

transferred Type of Connection

Circuit – Switched Technology

Packet - Switched

Technology

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GPRS IN INDIA

BPL MobileBharti CellularHutchison MaxHutchison EssarIdea Cellular

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A) GPRS AND PACKET DATA N/W Capacity and other end user aspects : It has ability to

offer data speeds of 14.1 Kbps to 171.2 Kbps, which allow easy Internet access.

QoS (Quality of Service) : Service precedence : is the priority of a service in relation to

another service. High , normal and low

Reliability : loss, duplication and mis- sequencing

Delay : end to end transfer time

Throughput : Maximum bit rate

Integral Part of the future 3G Systems : the use of GPRS in GSM n/w is known as 2.5G with limited Internet accessibility speed.

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B) GPRS ARCHITECTURE & N/W ENHANCEMENT

GPRS Subscriber Terminals GPRS BSS GPRS Networks Node GPRS Mobility Management

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GPRS SYSTEM ARCHITECTURE

BSC

SGSN

MS

BTS

BTS

Other GPRS

PLMN

GGSN

PDN

Gb

GdGp

Gn

Gf

Gs

Gc

GGSN

EIRHLR+GPRS

Register

MSC/VLR

D

SMS-GMSCSMS-INMSC

Gi

Gr

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INTERFACES Gb – Connects BSC with SGSN Gn – SGSN – SGSN/GGSN (in the same

network) Gp – SGSN –GGSN (in different networks) Gf – For equipment querying at

registering time Gi – Connects PLMN with external Packet

Data Networks (PDNs) Gr – To exchange User profile between

HLR & SGSN Gs – To exchange Database between

SGSN & MSC Gd – Interface between SMS & GPRS

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GPRS NETWORKS NODE

In the core network, the existing MSCs are based upon circuit-switched central-office technology, and they cannot handle packet traffic. Thus two new components, called GPRS Support Nodes, are added:

Serving GPRS Support Node (SGSN) Gateway GPRS Support Node (GGSN)

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1) Gateway GPRS support node (GGSN):

The Gateway GPRS Support Node acts as an interface and a router to external networks.

The GGSN contains routing information for GPRS mobiles, which is used to tunnel packets through the IP based internal backbone to the correct Serving GPRS Support Node.

The GGSN also collects charging information

connected to the use of the external data networks and can act as a packet filter for incoming traffic.

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2) Serving GPRS support node (SGSN):

The Serving GPRS Support Node is responsible for authentication of GPRS mobiles, registration of mobiles in the network, mobility management, and collecting information for charging for the use of the air interface.

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GPRS BSS

Each BSC will require the installation of one or more PCUs and a software upgrade. The PCU provides a physical and logical data interface out of the base station system (BSS) for packet data traffic.

The BTS may also require a software upgrade, but typically will not require hardware enhancement.

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TRANSMISSION PLANE & PROTOCOL ARCHITECTURE

RFL Physical RF Layer

SNDCP Subnetwork Dependent Convergence Protocol

BSSGP Base Station System GPRS Protocol

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PROTOCOL STACK

GSM RF

SNDCP

IP / X.25

Application

Um GnGb

MAC

RLC

LLC

IP / X.25

GTP

L1

L2

LLC

GSM RF

FrameRelay

MAC

RLC BSSGP

L1bis

BSSGPFrameRelay

LLC

SNDCP GTP

L1bis L1

L2

IP

MS BSS (PCU) SGSN GGSN Gi

IP

UDP/TCP

UDP/TCP

TRANSMISSION PLANE & PROTOCOL ARCHITECTURE

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Information transfer control procedures (e.g., flow control, error detection, error correction and error recovery), see Figure . The needed protocols are

SNDCP Subnetwork Dependent Convergence Protocol

LLC Logical Link Control RLC Radio Link Control MAC Medium Access Control PLL Physical Link Layer RFL Physical RF Layer BSSGP Base Station System GPRS Protocol IP Internet Protocol TCP Transmission Control Protocol UDP User Datagram Protocol GTP GPRS Tunneling Protocol

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1) SNDCP - SUB NETWORK DEPENDENT CONVERGENCE PROTOCOL

Used to transfer data packets between SGSN and MS

Multiplexing of several connections of network layer onto one logical connection of underlying LLC layer

Compression and decompression of user data and header information

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2) BSSGP-(BSS GPRS APPLICATION PROTOCOL)

Delivers routing & Quality of Service related information between BSS and SGSN

LLC

N/W Service.

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3) DATA LINK LAYER Divided into two sub layers :

• LLC layer (between MS-SGSN)

• RLC/MAC (between MS-BSS)

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LLC-LOGICAL LINK CONTROL

Establishes highly reliable logical link between MS & its assigned SGSN

Works either in acknowledged or unacknowledged modes

Data confidentiality is ensured by ciphering functions

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RLC/MAC LAYER Radio Link Control(RLC)

Establish a reliable link between MS & BSS Segmentation and reassembly of LLC frames

into RLC data blocks

Medium Access Control(MAC) Controls access attempts of an MS on radio

channels shared by several MSs Employs algos. for contention resolution,

multiuser multiplexing on PDTCH

Both ack and unack. Modes of operation are supported in RLC/MAC layer

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4) PHYSICAL LAYER

Divided into two sub layers : Physical Link Layer (PLL) Physical RF Layer (RFL)

PLL – Provides a physical channel between MS and BSS

Channel coding, interleaving, detection of physical link congestion

RFL - Operates below PLL

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C) GPRS NETWORK OPERATIONS

Attachment and De-attachment procedure APN- Access Point Name Mobility Management Routing Communicating with IP N/W

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1.ATTACHMENT AND DE-ATTACHMENT PROCEDURE

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ATTACHMENT & DETACHMENT PROCEDURE

GPRS attach- User is registered in SGSN, after authentication

check from HLR- SGSN assigns P-TMSI to MS

•GPRS detach- Disconnection of MS from GPRS network is called

GPRS detach- It can be initiated by MS or by network(SGSN or

HLR)

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SESSION MANAGEMENT IN ATTACHMENT PROCEDURE

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PDP CONTEXT ACTIVATION

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2. ACCESS POINT NAME Access Point Name (APN) is a configurable

network identifier used by a mobile device when connecting to a GSM carrier.

The carrier will then examine this identifier to determine what type of network connection should be created.

for example: what IP addresses should be

assigned to the wireless device, what security methods should be used, and how or if, it should be connected to some private customer network.

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STRUCTURE OF APN Network Identifier: Defines the external network

to which the Gateway GPRS Support Node (GGSN) is connected. Optionally, it may also include the service requested by the user. This part of the APN is mandatory

Operator Identifier: Defines the specific operator’s packet domain network in which the GGSN is located. This part of the APN is optional. The MCC is the Mobile Country Code and the MNC is the Mobile Network Code which together uniquely identify a mobile network operator.

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3. MOBILITY MANAGEMENT GPRS Mobility Management (GMM) is a GPRS

signaling protocol that handles mobility issues such as roaming, authentication, and selection of encryption algorithms.

GPRS Mobility Management, together with Session Management (GMM/SM) protocol support the mobility of user terminal so that the SGSN can know the location of a mobile station (MS) at any time and to activate, modify and deactivate the PDP sessions required by the MS for the user data transfer.

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If the MS moves to a new Location Area, it also moves to a new Routing Area. Each RA is identified by a routing area identifier (RAI). This is made up of a location area identifier (LAI) and a routing area code (RAC).

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4.ROUTINGThere are three important routing schemes: Mobile-originated message: This path begins at

the GPRS mobile and ends at the host

Network-initiated message when the MS is in its home network: This path begins at the host and ends at the GPRS mobile.

Network-initiated message when the MS roams to another GPRS network: This path begins at the host of visited network and ends at the GPRS mobile

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D) DATA SERVICES IN GPRS

1. Application Mode

Delivers routing & Quality of Service related information between BSS and SGSN

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2.GTP – GPRS TUNNELING PROTOCOL GTP tunnels user data packets and related

signaling information between GSNs

Signaling is used to create, modify and delete tunnels

Defined both at Gn and Gp interface

Below GTP, TCP or UDP are employed to transport the GTP Packets within backbone network

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INTER WORKING WITH IP NETWORKS

GPRS n/w can be interconnected with an IP-based packet data network

GPRS supports both IPv4 and IPv6 GPRS n/w looks like IP sub network and

GGSN looks like a IP router DHCP, DNS servers are installed

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GPRS –INTERNET CONNECTION

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WORKING OF GPRS Each voice circuit in GSM transmits the

speech on a secure 14kbps digital radio link between the mobile phone and a nearby GSM transceiver station.

The GPRS service joins together multiple speech channels to provide higher bandwidth data connections for GPRS data users. The radio bandwidth remains the same, it is just shared between the voice users and the data users.

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GPRS HANDSETS

The key use for GPRS is to send and receive data to a computer application such as Email, web browsing or even telemetry.

To use GPRS the service is 'dialed' in a similar manner to a standard data call at which point the user is 'attached' and an IP address is allocated.

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GPRS MOBILE DEVICES(CONT…) The three standard methods to connect

your computer to GPRS mobile phone are:

1… Infrared 2… Data-cable3… Bluetooth

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BEARERS IN GPRS

GPRS supports following types of data services:

1) SMS2) WAP3) MMS

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GPRS ROAMING

In the short term don't expect to be able to roam to many countries with GPRS, many networks are still negotiating to set up roaming agreements. Technically there are two type of GPRS Roaming

1… Home Network Roaming 2… Local Network Roaming

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GPRS SECURITY

The radio interface is considered to be relatively secure being controlled by the GSM network's security - (SIM card + HLR). Security issues arise when data needs to leave the GPRS network to be delivered to either the Internet or a company LAN.

Internet connectivity is the cheapest and most common - and here you can take charge of security by encrypting sensitive data.

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E) GENERAL APPLICATIONS OF GPRS Communications—E-mail and fax; Intranet/Internet access Value-added services (VAS)—Information services;

games E-commerce—Retail; ticket purchasing; banking;

financial trading Location-based applications—Navigation; traffic

conditions; airline/rail schedules; location finder Vertical applications—Freight delivery; fleet

management; sales-force automation Advertising

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APPLICATIONS OF GPRS Web browsing Corporate & Internet Email Vehicle Positioning Remote LAN Access Home Automation Document Sharing/Collaborative working E-Commerce Banking Financial Trading Unified Messaging

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LIMITATIONS OF GPRS Limited Cell Capacity for All Users Speeds Much Lower in Reality Support of GPRS Mobile Terminate by

Terminals is Not Ensured Suboptimal Modulation Transit Delays No Store and Forward

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ADVANTAGES OF GPRS GPRS will enable a variety of new and unique services

to the mobile wireless subscriber. These mobile applications contain several unique characteristics that enhance the value to the customers.

First among them is mobility—the ability to maintain constant voice and data communications while on the move.

Second is immediacy, which allows subscribers to obtain connectivity when needed, regardless of location and without a lengthy login session.

Finally, localization allows subscribers to obtain information relevant to their current location

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F) BILLING AND CHARGING IN GPRS “Data sells, voice pays” Saying in the wireless business community.For voice NW teriffs are based on distance and time.

Billing: The GPRS specification charging information that

must be collected. Destination and source address. Usage of radio interface. Usage of external packet data networks GPRS resources and mobile location.

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BILLING

GGSN

MSC

PSTN

BSC

SGSN

GPRS Network

Charging Gateway

Mediation

MSC

Billing

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SALIENT FEATURES OF GPRS Important step on the path to 3G Standardized by ETSI GPRS is an overlay network over the GSM Provides Data Packet delivery service Support for leading internet

communication protocols Billing based on volume of data

transferred Utilizes existing GSM authentication and

privacy procedures.

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THANK YOU