GSM: The European Standard for Mobile Telephony

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GSM The European Standard for Mobile Telephony

• Presented by
• Rattan Muradia
• Requirement for course CSI 5171

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Presentation Objective

• No discussion of mobile network concepts already
  covered (MSC, BSC, HLR, VLR, registration, call
  setup, roaming, handover, OSS etc..)
• GSM Architecture
• Focus on features specific to GSM
• Provide basic information required for
  presentations on CAMEL, GPRS and UMTS

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Evolution of Digital Mobile Systems

• 1st Generation, Analogue Cellular - AMPS,
  ETACS, NMT, C-NET...
• 2nd Generation, Digital Cellular - GSM, PDC,
  DAMPS, CDMA...
• 2nd Generation Cordless - DECT, PHS...
• 2nd Generation Satellite - Iridium, Globalstar..
• 2.5 Generation GPRS...
• 3rd Generation Universal - IMT-2000, UMTS

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Digital Mobile Systems
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GSM Overview

• Developed in Europe
• One of first intelligent networks with
  distributed processing
• International roaming
• 174 countries, 647 million subscribers
• 67 of world wireless market share

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GSM Network

• Mobile Station (MS)
• Base Station Subsystem (BSS)
• Network and Switching Subsystem (NSS)
• Operation and Support Subsystem (OSS)

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GSM Network Architecture
INTERFACE TO LANDTELEPHONE NETWORKS
STOLEN, BROKEN CELLPHONE LIST
LIST OF ROAMINGVISITORS
ENCRYPTION, AUTHENTICATION
LIST OF SUBSCRIBERS IN THIS AREA
SOURCE UWC
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GSM Reference Model
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GSM Protocol Stack
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GSM Address and Identifiers

• International Mobile Subscriber Identity (IMSI)
• 3 digit Mobile Country Code 2 digit Mobile
  Network Code 10 digit Mobile Subscriber
  Identification Number
• International Mobile Equipment Identity (IMEI)
• 19 digit unique ID, used by air interface, stored
  in EIR
• Mobile Subscriber ISDN Number (MSISDN)
• upto 3 digit Country Code 2-3 digit national
  Destination Code max 10 digit Subscriber Number
  
• mapped to MSRN by HLR
• Mobile Station Roaming Number (MSRN)
• temporary ISDN number assigned by VLR

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GSM Mobile Station

• Each MS identified by IMEI
• In addition to the physical equipment common to
  most MS, GSM equipment includes a SIM.
• Subscriber Identity Module (SIM) provides true
  mobility. Access to subscribed services
• regardless of location of the terminal
• regardless of use of specific terminal
• SIM contains IMSI, secret key for authentication
  more information

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GSM Databases

• Equipment Identity Register (EIR)
• contains list of valid mobile equipment (IMEI)
• an IMEI can be marked invalid if MS is stolen,
  unauthorized or defective
• Authentication Center (AuC)
• protected database that stores authentication and
  encryption parameters
• used to verify user identity and ensure
  confidentiality of each call

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GSM Call Delivery
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GSM Services

• Patterned after ISDN
• Bearer Services
• sync, async data transport, represent layers 1-3
• also used by higher layers to offer teleservices
• Teleservices
• voice, SMS, FAX, Teletext etc..
• Supplementary Services
• modify or supplement teleservices

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GSM Services - Phase 1
Offered by all operators in 1991.
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GSM Services - Phase 2
Introduced in 1996. Major rework of standards.
Backward compatible. More supplementary services.
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GSM Phase 2

• Increased globalization using SIM, multiband
  systems and terminals
• Phase 2
• increase network capacity via spectral efficiency
• improve voice quality
• group call (party line)
• integration of packet services (on air interface)
  and higher data speeds (GPRS)
• expand supplementary services (SMS Forwarding,
  Multiple Subscriber profile, Call Xfer etc..)

(see GPRS presentation by Miao Lu and Nancy
Samaan on April 5th).
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GSM Phase 2

• No complete revision of standards in Phase 2
• Each subject area treated separate, allowed to
  implement and introduce independently
• Standardize mechanisms for service introduction,
  not complete services
• Reduce time-to-market, allow differentiation
• GSM already has similarities with IN (MSCSSP,
  HLRSCP, SS7 signaling)
• Convergence of GSM and IN - CAMEL

(see CAMEL presentation by Tina Deng and Yinyan
Zhou on April 2th).
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Beyond GSM - 3GRoad to UMTS/IMT2000

• New generation of mobile systems based on IP
• Must support large number of subscribers
• Wide range of voice and data services
• Build on existing GSM infrastructure as much as
  possible.
• Higher bandwidth for multimedia applications
• new radio interface
• better use of spectrum

(see IMT2000 presentation by Mingdi Zhao and Wei
Lin on April 9th).
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Questions?
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GSM/GPRS/UMTS
Backup slide 1
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GSM Network Architecturebackup slide
Backup slide 2
SOURCE UWC
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GSM Protocol Stack
Backup slide 3