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ALTHOSSimpl if ying Know l edge(t m)
Introduction to GSM
This slideshow describes the basic components, technologies used, and operation of Global System for Mobile Communication - GSM -
systems. You will discover the evolution of GSM; 1st generation analog systems, 2nd generation GSM systems (digital voice), 3rd generation multimedia, and 4th generation wideband ultra broadband systems.
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Introduction to GSM © Althos, 2009-2013 page 2
Introduction to GSM
Lawrence [email protected]:
www.linkedin.com/in/lharte/
Lawrence Harte is a mobile communication expert who has developed, designed, and managed many types of communication products and services since 1985.
Mr. Harte is the publisher and editor of Mobile Video magazine and author of over 112 books with over 53 on wireless communication. As a magazine editor, he has interviewed over 2100 companies in the mobile communication industry to discover the key issues and solutions of the wireless industry.
Mr. Harte has worked for Ericsson/General Electric, Audiovox/Toshiba and Westinghouse and has consulted for hundreds of other companies. He is the inventor of several patents on communication technology.
Mr. Harte Holds many degrees and certificates including an Executive MBA and a BSET.
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GSM Topics
Global System for Mobile Communication GSM Services GSM Products (Mobile Devices) GSM Radio Technology Digital Audio and Baseband Radio Channels Logical Channels GSM Network GSM System Operation GSM Evolution
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What is GSM?
Mobile Communication System
Digital Media Formats
Functional Sections- Mobile Stations (MS)- Base Station Subsystem (BSS)- Network and Switching System (NSS)
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GSM Services
Voice Services - Circuit Switched Data Services - Low to Medium Speed Short Messaging Services - Location Multicast Service
- Group Call - Voice Broadcast
Packet Data - Internet Browsing
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GSM Devices
Subscriber Identity Module (SIM)
Mobile Telephones PCMCIA Air Cards Embedded Radio
Modules External Radio Modems
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Subscriber Identity Module (SIM)
Holds User Identification Data
Microprocessor Memory Software
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GSM Radio Technology
Frequency Reuse Time Division
Multiple Access (TDMA)
RF Power Control
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Digital Audio and Baseband
Analog to Digital Conversion Digital Speech Compression Channel Coding
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Analog to Digital Conversion
Voice Coding- 13 kbps Full Rate- 6.5 kbps Half Rate
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Digital Speech Compression
Analyze Voice
Use Code Book to Identify Human Sounds
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Channel Coding
Error Protection- CRC- Block- Convolutional
Signaling Commands- Fast- Slow
Time Slot Allocation
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Echo Cancellation
Audio Analysis Time Shifting Echo Modeling
- delay- amplitude
Signal Subtraction
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GSM Radio Channels
Radio Channel Structure
Time Slot Structure Frame Structure Dynamic Time
Alignment
A GSM radio channel is a 200 kHz communications channel that transfer digital information from a source to a destination. The GSM radio channel is
divided into time slots and frames to allow multiple communication paths (logical channels) to share a single radio transmission channel.
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Radio Channel Structure
200 kHz RF Channel Bandwidth
Frequency Duplex Channels- Downlink- Uplink
Time Offset
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Time Slot Structure
Normal Burst Random Access Burst (Shortened Burst) Frequency Correction Burst Synchronization Burst
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Frame Structure
GSM Frame- 4.615 msec
Multiframes- Traffic- Control
Superframes
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Logical Channels
Traffic Channels - User Data Control Channels - Signaling
- Broadcast - System Information- Common Control - Paging and Access- Dedicated Control - On an Assigned Channel
The GSM system divides up the RF communications channel into logical channels that serve different purposes. Traffic channels carry user data (voice
and data). Control channel transport signaling messages.
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Traffic Channels
Full Rate (TCH/F) Half Rate (TCH/H) Eighth Rate (TCH/8)
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Control Channels
Beacon (Broadcast) Channels (BCH) Common Control Channels (CCCH) Dedicated Control Chanels
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GSM Network
Base Stations Repeaters Switching Centers Network Databases Wireless Network
System Interconnection
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Base Stations
Radio Antenna Towers
Radio Equipment- Transmitters- Combiners- Multicouplers- Receivers- Controllers
Communication Links Power Supplies
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GSM Switching Systems
Mobile Switching Center (MSC)- circuit switching
Packet Nodes (SGSN)- packet data
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Network Databases
Home Location Register (HLR)- Registered with Operator
Visitor Location Register (VLR)- Operating in System (including home subscribers)
Equipment Identity Register (EIR)- Identifies Stolen Equipment
Authentication Center (AuC)- Security Validation
SMS Center (SMSC)- Message Reception and Routing
Group Call Register (GCR)- Dispatch Type Services
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GSM System Operation
Mobile Telephone Initialization
Updating Location Waiting for Calls (Idle) Cell Reselection System Access Mobile Call Origination Mobile Assisted Handoff
Transferring Calls Between Call Sites
Receiving a Call on a Mobile Telephone
Conversation Mode Connected Mode Authentication
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System Access
Randomly Attempt Access
Receive RF Channel and Time Slot Assignment
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Mobile Call Origination
Request Access- random attempts
Assign Traffic Channel- frequency- time slot
Setup Audio Connection
Open Audio Path- hear ringing
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Receiving a Call
Send Page Alert Message to Last Known Mobile Location- start ringing
Mobile Request Access
Assign Traffic Channel
Open Audio Path
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Mobile Assisted Handoff (MAHO)
Signal Quality Fall Below Allowable Level
System Sends List of Channels for Mobile to Monitor
Mobile Periodically Returns Measurements
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GSM Evolution
General Packet Radio Service (GPRS) Enhanced Data for Global Evolution (EDGE) Wideband Code Division Multiple Access (WCDMA) UMTS Long Term Evolution (UMTS LTE)
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Wireless Resources
Wireless Dictionary (17,000+ Definitions) – www.WirelessDictionary.com
Intro to GSM Book (by Lawrence Harte) – http://www.althosbooks.com/intogsm.html - Also Available from Amazon and Barnes & Noble
Mobile Video Magazine – www.mVideoMagazine.com
Wireless Trade Shows - http://www.mvideomagazine.com/events.asp
More Detailed GSM Tutorial (with notes):
http://www.tvdictionary.com/tutorial/gsm-tutorial-title-slide.html
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Summary
GSM Continues to Evolve over Time
GSM - Worldwide Mobile Wireless System Can Provide, Voice, Messaging, and Data Services Many Types of Mobile Devices - Voice, Data Only 200 kHz Digital RF Channel - 8 Slots per Frame Mix of Logical Channels - Traffic and Control GSM Network - Base Stations, Switches, and Databases Evolved into GPRS, EDGE, WCDMA, UMTS LTE