Slide thông tin di động đại học bách khoa hà nội chương 6 general packet radio service

2/17/2014

Trường Đại học Bách Khoa Hà Nội
Khoa Điện tử Viễn thông

Thông tin di động

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Mobile Communications

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TS. Đỗ Trọng Tuấn
Bộ môn Kỹ thuật thông tin

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Hà Nội, 9-2010

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(GPRS)

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General Packet Radio Service

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General Packet Radio Service

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(GPRS)

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RF air
interface

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GPRS Network Architecture

BSC

BTS

MSC/VLR

SMSC

HLR

Packet
Control Unit
(PCU)

SGSN

SGSN

GGSN
Charging
Gateway
Function

PDN

Billing

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GPRS system architecture

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How is GPRS seen by external networks and
GPRS users?
HOST

155.222.33.55

GPRS
SUBNETWORK
SUBNETWORK
155.222.33.XXX
"Router"
SUBNETWORK
131.44.15.XXX

SUBNETWORK
191.200.44.XXX

Corporate 1
Router

HOST
191.200.44.21

Local
area
network

Packet
Data
network
network

Router

Corporate 2

(Internet)

Local
area
network

HOST
131.44.15.3

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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

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procedures.

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Advantage of GPRS

Use of packet-switching technology

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Enables multiple users to share air interface

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resources


Users feel their services to be “always on”

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GPRS is primarily for data communication and
not for voice communication.



GPRS communicates using TCP/IP protocol
similar to the internet.

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GPRS
Tốc độ truy nhập

Không truy
nhập

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Tốc độ truy nhập

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Applications

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Standard data network protocol based

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 IP based applications
• WWW, FTP, Telnet, ...
• Any conventional TCP/IP based applications

 X.25 based applications
• Packet Assembly/Disassembly (PAD) type approach

GPRS specific protocol based

 Point-to-point applications
• Toll road system, UIC train control system
 Point-to-multipoint applications
• Weather info, road traffic info, news, fleet management

SMS delivery (GPRS as a bearer for SMS)

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Mobility Management state model in GPRS

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QoS Profile for GPRS Bearers

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Describes applications characteristics and QoS
requirements

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4 parameters:
• Service precedence


3 classes

• Reliability parameter


3 classes

• Delay parameters


4 classes

• Throughput parameter


Maximum and mean bit rates

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QoS Precedence classes (from [GSM 03.60])

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Reliability classes (from [GSM 02.60])

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SDU (Service Data Unit)

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Delay classes (from [GSM 02.60])

Peak throughput classes (from [GSM 03.60])

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Mean throughput classes (from [GSM 03.60])

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PDP and PDF contexts

PDP : Packet Data Protocol

PDF : Packet Data Flow

NSAPI : Network layer Service Access Point Identifier

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Channel coding schemes applied per time slot

• The Packet Data Traffic Channels (PDTCHs) use four different channel
coding schemes, described in [GSM 04.60] to transfer the packet data
traffic. Above table lists the used channel coding schemes and the data

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rates that can be obtained by using these coding schemes per time slot.
• The maximum data rate that can be obtained on PDTCH channels is
8*21.4 kb/s = 171.2 kb/s

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i.e., (8 time slots) * (Maximum data rate for CS-4 for a time slot).

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PDP Context

PDP: Packet Data Protocol (PDP) is a network protocol

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used by an external packet data network interfacing to
GPRS.


PDP Context: Information sets held in MS and GSNs
for a PDP address

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NSAPI: Network Service Access Point Identifier. An
integer value in the range [0; 15], identifying a certain
PDP Context.

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PDP Context Activation Procedure

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+ IP assignment
+ Roaming

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SIM300

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

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Features

Tri or Quad-Band GSM/GPRS
40x33x2.85mm 60-pin ENTERY board to board connector
Support sleep mode(about 3mA)
Embeded TCP/IP protocol
Autobauding
Support RTC function
Over-temperature automatic shutdown
Operation temperature -20~55Ԩ
Supply voltage 3.4-4.5V
Support FAX and USSD

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SIM508 and SIM548
Features
Tri or quad-band GSM/GPRS+GPS

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80PIN CONNECTOR

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GSM part based on SIM300C



GPS receiver with SiRFstar III GSC3f chip set

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Processor type ARM7/TDMI

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Software version: SiRF GSW3

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Two serial GPS interfaces

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Size: 55±0.15 x 34±0.15 x 2.9±0.3 mm

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

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SIM508 and SIM548

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Application


PND (Personal Navigation Device)



AVL (Auto Vehicle Location)



Tracing

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