دنیای فناوری

دنیای مجازی
شنبه 10 شهریور‌ماه سال 1386 :: 05:05 ق.ظ ::  نویسنده : محمدرضا گرامی

This figure shows how a GSM system can be upgraded to offer GPRS services. This diagram shows that an existing GSM channel is removed, replaced, or upgraded to have GPRS and EDGE/EGPRS modulation and transmission capability. This diagram shows that packet control unit (PCU) must be added to the base station controller (BSC) and packet data switching nodes and gateways must also be added to allow data packets to be routed between mobile devices and data networks (e.g. the Internet).

GPRS Addressing

This figure shows how a GPRS system uses multiple addresses to allow IP datagram packet to transfer between the end user an Internet web sites. This example shows that the end user mobile data device uses its IMSI to communicate with the SGSN. The SGSN links this IMSI to a private IP address that routes the data packets to a gateway router. When the data packets reach the GGSN, they are linked (mapped) to a public Internet address that allows the packet to reach its destination.

Table of Contents

Introduction to GPRS and EDGE

Global System for Mobile Communication (GSM)
General Packet Radio Service (GPRS)
Enhanced Data for Global Evolution (EDGE)
Enhanced GPRS (EGPRS)
Compact GPRS

Upgrading GSM to GPRS and EDGE

GPRS and EGPRS Industry Specifications

Packet Data Services

Mobile Services (M-Services)
Stream Prioritization
Enhanced Messaging Service (EMS)
Multicast Services
Asynchronous Channels
Asymmetric Channels
Quality of Service (QoS)
-Conversation Class
-Streaming Class
-Interactive Class
-Background Class

Short Messaging Services
Location Based Services (LBS)
Packet Data Service Measurement Types
-Data Throughput
-Packet Loss

GPRS and EGPRS Devices (Mobile Stations)

Mobile Device Classes
-Class A – Simultaneous Voice and Data
-Class B – Automatic Transfer of Voice and Data
-Class C – Single System Selection
-Dual Transfer Mode (DTM)
-Multi-slot Class

Subscriber Identity Module (SIM)
External Modems (USB or Ethernet)
PCMCIA Air Cards
Embedded Radio Modules
Mobile Telephones
Dual Mode Capability

GPRS and EGPRS Radio

RF Channel Types
Frequency Bands
Frequency Reuse
Frequency Hopping
RF Power Control
Dynamic Time Alignment
Channel Structure
Coding Schemes (CS)
Data Packet Encapsulation
Packet Data Channel Sharing


Physical Channels
-Packet Data Channel (PDCH)

Logical Channels
Traffic Channels
Control Channels
GSM Logical Channels
-Broadcast Channels (BCH)
-Common Control Channels (CCCH)
-Dedicated Control Channels
-General Logical to Physical Channel Mapping for GSM

GPRS Logical Channels
-Packet Broadcast Control Channel (PBCCH)
-Packet Common Control Channels (PCCCH)
-Packet Data Traffic Channel (PDTCH)
-Packet Dedicated Control Channels (PDCCH)
-Compact Mode of GPRS


Base Stations
-Packet Control Unit (PCU)
-Communication Links

Switching Centers
-Mobile Switching Centre (MSC)
-Serving General Packet Radio Service Support Node (SGSN)
-Gateway GPRS Support Node (GGSN)

Network Databases
-Home Location Register (HLR)
-Visitor Location Register (VLR)
-Equipment Identity Register (EIR)
-Charging Gateway (CG)
-Billing Center (BC)
-Authentication Center (AuC)
-SMS Service Center (SC)

Wireless Network System Interconnection
-Public Switched Telephone Network (PSTN)
-Public Packet Data Network (PPDN)
-Interworking Function (IWF)

IP Backbone Network
-GPRS Roaming Exchange (GRX)


Mobile Device
-Mobile Station ISDN (MSISDN)
-International Mobile Subscriber Identity (IMSI)
-International Mobile Equipment Identifier (IMEI)
-Temporary Mobile Subscriber Identity (TMSI)
-Temporary Block Flow (TBF)
-Temporary Flow Identifier (TFI)

Infrastructure Addressing
-Access Point Naming (APN)
-GPRS Tunneling Protocol (GTP)
-Tunneling End Point Identifier (TEID)

IP Addressing
-Static and Dynamic (DHCP) Addressing

GPRS and EDGE/EGPRS System Operation

Standby State
Initial Assignment/Access
Ready State (Connected Mode)
-Dynamic Allocation
-Extended Dynamic Allocation
-Fixed Allocation
-Packet Acknowledgement

Always-on Condition
Registration Area Updates
GPRS Roaming
Voice Call and Data Session Transfer Operation
Data to Voice (GPRS to GSM)
Transfer Between GPRS and IS-136

GPRS and EGPRS Radio Layers

Physical Layer
Medium Access Control (MAC) Layer
Radio Link Control (RLC) Layer
Logical Link Control (LLC) Layer
Subnetwork Dependent Convergence Protocol (SNDCP)

Future Evolution

Third Generation GSM (3GSM)

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