1. Traffic/Signaling

2. Traffic/Signaling
 The network can carry two types of information:
 Traffic: it concerns all the «user to user»
information. It can be voice as well as data.
 Signaling: the network also requires to carry
information for its own working. Their
purposes are numerous: traffic data routing,
maintenance, security... These data are
usually not visible from user’s point of view.

3. Before GSM: Mobile Telephony
Milestones

4. Before GSM: Mobile Telephony
Milestones
 1876: The telephone was introduced to the public at the Centennial
Exposition of the United States in Philadelphia. Alexander Graham Bell was
able to transmit speech electrically, in one direction only, over a copper wire
circuit of several hundred feet in length. This “speaking telegraph” was quickly
perfected for adequate two-way communication and was offered for business
and residential service the following years. Within a short time there were
thousands, then tens of thousand, and soon hundreds of thousand of paying
customers.
 End of the 19th century: While the struggle to search for the ways to
utilize the copper wire transmission facility more and more efficiently, a young
German scientist named Heinrich Rudolf Hertz discovered a strange and
wonderful phenomenon: from an electric spark there seemed to emanate
invisible waves of force which could be captured at a distant location by a
suitably constructed receiving device. Hertz’s own experiments extended only
a few yards.
 1897: Guglielmo Marconi shows the first wireless transmission over 15 km in
Bristol. A few years later(1901), G. Marconi transmitted these waves
overseas, and began to call it Radio.

5. Before GSM: Mobile Telephony
Milestones
 1946: The first public mobile telephone service was introduced in
twenty five American cities. Each system used a single, high-powered
transmitter and large tower in order to cover distances of over 50 km in
a particular market. Nevertheless these early FM push-to-talk
telephone systems of the late 1940s used 120 kHz of RF bandwidth in
a half duplex mode (only one person on the telephone call could talk at
a time), even though the actual telephone-grade speech because of
the kHz of baseband spectrum. The large RF bandwidth was needed
because of the difficulty in mass producing tight RF filters and low-
noise, front-end receiver amplifiers.
 1970: A.Pinet introduced in France the first digital switch.
 1982: The first commercial cellular system was turned on in Chicago.
 1992: GSM, the first fully digital cellular system, was introduced on in
Germany and in France.

6. Analog Cellular Systems Around the
World

7. Analog Cellular Systems Around the
World
There are several different types of analog cellular
systems:
 NMT450 and NMT900: Scandinavia, Benelux, Spain,
Austria, France, Switzerland

AMPS (Advanced Mobile Phone System ) in more 34
countries: U.S.A., Canada, Argentine, Chile, Indonesia,
Brazil
 Australia, Republic of Congo
 TACS (Total Access Communication System) in UK
Ireland and Italy
 R2000: France
 C450: Germany
 NTT (1979) cellular and JTACS (1988) in Japan
 RTMS: Italy.

8. AMPS

AMPS is a first-generation cellular technology
 This cellular service operates in the 800 MHz Cellular FM
band. For each market area
 Its is the analog mobile phone system standard
developed by Bell Labs, and officially introduced in the
Americas in 1983 and Australia in 1987
 As of February 18, 2008, Carriers in the United States
were no longer required to support AMPS and companies
such as AT&T and Verizon have discontinued this service
permanently. AMPS was discontinued in Australia in
September 2000

9. AMPS
 AMPS pioneers fathered the term "cellular" because of its
use of small hexagonal "cells" within a system.
 This allowed a larger number of phones to be supported
over a geographical area
 It suffered from some weaknesses when compared to
today's digital technologies
 Very susceptible to static and noise
 No protection from eavesdropping
 Later, many AMPS networks were partially converted to
D-AMPS

D-AMPS is a digital, 2G standard

10. Development of the GSM
Standard
 1991: First system-trial are running at
Telecom 91 exhibition. The GSM
Recommendations comprise:
 1992: Official commercial launch
of GSM service in Europe.

11. Development of the GSM
Standard
 1993: Aside the GSM has 62 members
(signatories) in 39 countries worldwide; and in
addition 32 potential members (observers,
applicants) in 19 other countries. GSM networks
are operational in Denmark, Finland, France,
Greece, Ireland, Italy, Luxembourg, Norway,
Portugal, Sweden, Switzerland, United kingdom.
 The end of 1993 shows one millions
subscribers to GSM networks, however more
than 80% of them are to be found in Germany
alone.

12. GSM (short statistics, 2004)
 No. of Countries/Areas with GSM System: 199
 Worldwide GSM Subscribers as
at end of 2007 = 2,685,060,046

Ratified Operator and Regulator Members = 585
 SMS messages sent per month: 24 Billion
 GSM accounts for 73 % of the World's digital market and
72% of the World's wireless market

13. GSM (statistics, end of 2007)

14. GSM Benefits

15. GSM Benefits
The features and benefits expected in the GSM
 Superior speech quality (equal to or better than
the existing analog cellular technology),
 Low terminal and services costs,
 A high level of security (confidentiality and fraud
prevention),
 International roaming (under one subscriber
directory number),
 Support of low power hand-portable terminals,
 Variety of new services and network facilities.

16. GSM Benefits
 It was a logical consequence of the prevailing
reality that a measure of Inter-working
compatibility with the services offered by other
existing telecommunication networks was
sought. In particular, the basis for the services
in GSM standard can be found in the ISDN
concept.

17. GSM: System Architecture

18. GSM: System Architecture

19. Mobile Station

20. Mobile Station
 The Mobile Station (MS) is composed of three
parts:
 The handset includes the radio equipment
(receiver-transmitter) and the Man-Machine Interface
(MMI),
 The SIM card (Subscriber Identity Module-card):
this smart card allows the identification of any
subscriber (not only of his equipment) by the
network. In particular, he can borrow any mobile
without changing anything from the network point of
view since he keeps the same SIM-card,
 The battery.

21. Mobile Station (MS)
 Mobile Subscriber Identity Module (SIM)
 Removable plastic card
 Stores Network Specific Data such as list of carrier
frequencies and current LAI (Location Area
Identifier).
 Stores International Mobile Subscriber Identity
(IMSI) + ISDN
 Stores Personal Identification Number (PIN) &
Authentication Keys.
 Also stores short messages, telephone book etc.

22. SIM-Card and GSM Mobile Equipment

23. SIM-Card and GSM Mobile Equipment
 The subscriber is identified within the system when he
inserts the SIM-Card in the mobile equipment and
switches it on. This provide a considerable amount of
flexibility to the subscribers since they can use any GSM-
specified mobile equipment.
 With the SIM-Card the idea of "personal
communication" is already realized: the user only
needs to take his smart card on a trip. You can rent a
mobile equipment unit at the destination, even in other
country, and insert your own SIM-Card. Any call you
make will be charged to your home GSM account. Also
the GSM system is able to reach you at the mobile unit
you are currently using.

24. The SIM-Card Functions

25. The SIM-Card Functions
 The SIM-Card is a removable smart card, the size of a
credit card, and contains an integrated circuit chip with a
microprocessor, random access memory, and read-only
memory.
 When a mobile users want to make a call, they insert
their SIM-Card and provide their Personal Identity
Number (PIN), which is compared with a PIN stored
within the SIM-CARD.
 The PIN can also be permanently bypassed by the
subscribers if authorized by the service provider.
Disabling the PIN code simplifies the call setup but
reduces the protection of the user's account in the event
of a stolen SIM-CARD.

26. Subscriber Identification
 The International Mobile Subscriber
Identity (IMSI) is the primary identification of
the subscriber within the GSM network and is
permanently assigned to him.
 The Mobile Subscriber ISDN Number
(MSISDN) is the number that the calling party
dials in order to reach the GSM subscriber. It is
used by the land networks to route calls toward
an appropriate GSM network. MSISDN is stored
in HLR.

27. GSM Mobile Equipment
 The Mobile Station (MS ) includes radio equipment and the man
machine interface (MMI) that a subscriber needs in order to access
the services provided by the GSM network.
 Mobile Stations can be installed in vehicles or can be portable or
hand-held stations. The mobile station includes provisions for data
communication as well as voice.
 Mobile Stations transmit and receive messages to and from the GSM
over the air interface to establish and continue connection through the
system.
 Each mobile station has an International Mobile Equipment
Identity (IMEI) that is permanently stored in the mobile unit. Upon
request, the MS sends this number over the signaling channel to the
network. The IMEI is used to identify mobile units that are reported
stolen or operating incorrectly.

28. Mobile Identification
 Stored inside the Mobile Equipment.
 Some time can work without SIM card (example:
Emergency calls without SIM-Card) or when required by
the network (for maintenance).
 Can be used for EIR (Equipment Identification Register)
database updating (when existing):
 TAC = 6 digits describing the type of equipment,
 FAC = 2 digits for identification of the factory,
 SNR = 6 digits for the serial number of the device.
 The type of MS must be given to the NSS at the
beginning of each new connection, because this type
can change between calls. The subscriber may insert
this SIM-Card into another Mobile Equipment (ME).

29. Trends in Mobile Station
 Trends for MS are:
 Hands-free (2 W + booster 5 W).
 Increasing independence:
 idle mode: 40 hours to 140 hours,
 communication mode: 4 hours to 15 hours,
 Supplementary features (e.g. display of calling number).
 Additional features (e.g. voice recognition).
 Connection with terminals for data transmission:
 Modem on PCMCIA board for Laptop PC.

Modem integrated.
 Dual-band terminal (GSM 900/1800 MHz).
 Radio organizer (Nokia 9000).
 Versatile terminal (under JAVA software's): fax, internet, pager,
organizer.

30. Base Transceiver Station (BTS)
 One per cell
 Consists of high speed transmitter and receiver
 Function of BTS
 Controls several transmitters
 Provides two channels
 Signalling and Data Channel
 Performs error protection coding for the radio
channel

31. Base Station Controller (BSC)
 Controls multiple BTS
 Functions of BSC
 Performs radio resource management
 Assigns and releases frequencies and time slots for all the
MSs in its area
 Reallocation of frequencies among cells
 Hand over protocol is executed here
 Time and frequency synchronization signals to BTSs
 Knows which mobile stations are within the cell and
informs the MSC/VLR about this
 Power Management of BTS and MS
 know the exact location of a MS before a call is made

32. Mobile Switching Centre
(MSC)
 Switching node of a PLMN (Public Land
Mobile Network)
 Allocation of radio resource (RR)
 Handover
 Mobility of subscribers
 Location registration of subscriber
 There can be several MSCs in a PLMN

33. Gateway MSC (GMSC)
 Connects mobile network to a fixed network
 Entry point to a PLMN
 Usually one per PLMN
 Request routing information from the HLR and
routes the connection to the local MSC

34. HLR/VLR
 HLR - Home Location Register
 For all users registered with the network, HLR keeps
user profile
 MSCs exchange information with HLR
 When MS registers with a new GMSC, the HLR sends
the user profile to the new MSC
 VLR - Visitor Location Register
 VLR is responsible for a group of location areas,
typically associated with an MSC
 Contains the location of the active Mobile Stations

35. AuC/EIR/OSS
 AuC: Authentication Center
 is accessed by HLR to authenticate a user for service
 Contains authentication and encryption keys for
subscribers
 EIR: Equipment Identity Register
 International Mobile Station Equipment Identity (IMEI)
codes
 allows stolen or fraudulent mobile stations to be
identified
 Operation subsystem (OSS):
 Operations and maintenance center (OMC), network
management center (NMC), and administration center
(ADC) work together to monitor, control, maintain, and
manage the network

36. GSM identifiers
 International mobile subscriber identity (IMSI):
 unique 15 digits assigned by service provider = home country code +
home GSM network code + mobile subscriber ID + national mobile
subscriber ID
 International mobile station equipment identity (IMEI):
 unique 14 digits assigned by equipment manufacturer = type
approval code + final assembly code + serial number + spare digit
 Temporary mobile subscriber identity (TMSI):
 32-bit number assigned by VLR to uniquely identify a mobile station
within a VLR’s area

37. Explosive Growth in Wireless Data

38. Motivations

Growing demand of data services due to Internet
 PSTN/ISDN tends to become local islands
connected with the IP backbone
Solution:
 To associate the traditional GSM (Circuit
switched ) network with Packet switched, all IP
network
 No hardware/software change is requires in BTSs and
BSCs.
 Same radio interface
 GPRS uses the same Radio Access Network (RAN) as
GSM

A Packet Control Unit is added to the BSS

39. Basic characteristics
 Using from 1 to 8 time slots on the same carrier
 max bit rate 171.2 kb/s, 8*21.4 kb/s
 User charging based on the amount of data
transmission …
 Thus allowing, Always-On-Connections
 Interact with IP
 Supports various level of QoS

40. General Packet Radio
Service

41. Important elements
 Serving GPRS Support Node (SGSN)
 Tracks the location of the MS
 Provides routing and mobility management
 Authenticates the MS
 Manages the session
 Collects billing data
 IP packets from the MS are treated as IP packets first
time here
 Gateway GPRS Support Node (GGSN)
 Connects the GPRS network to other networks, e.g. the
Internet
 GSM VLR and HLR are used

42. GPRS Handovers
 There are no GPRS handovers as such
 Since there is no circuit to hand over
 The MS requests a cell reselection and the
packets are routed to the new cell
 Requires dynamic routing

43. General Packet Radio
Service
 GPRS is the first major revolution in GSM data, providing
speeds over 100 kbit/s on a pseudo-packet switched
radio interface and a real packet switched NSS. This will
encourage users to connect to high-speed applications
across the wireless network and optimizes the network
resources for data transmission. There are however some
limitations and the first implementations will have mobility
constraints. However, it is likely to attract users to internet
type services and provides operators with a natural
migration path towards 3G systems.

44. Universal Mobile Telecommunication
System
 UMTS, or more precisely IMT2000, will at first provide a
capacity advantage for wireless data networks that
become overcrowded.
 But it has to provide more than that.
 The higher data rates will allow applications such as
video and multimedia (support 2mb/s).
 Open architecture will provide a service environment
allowing a wide range of services to be developed by
operators and service specialists.
 Total global roaming is one of the objectives of the
specifications.

45. UMTS
 Handover
 Seamless handover between cells of one operator
 Efficient handover between UMTS and 2nd generation
 Compatibility with fixed network services
 ATM an ISDN services
 GSM services
 IP based services
 Facilities for quality of service provision
 Private and residential operators
 High spectrum efficiency
 Asymmetric band usage
 Reasonable network cost and complexity

46. Enhanced Data rate for GSM
Evolution
 GSM Enhanced Data rate for GSM Evolution or EDGE is often
referred to in GPRS context as the combination of the two
technologies is seen by some groups in the mobile industry as an
alternative for UMTS. This makes EDGE an alternative for
operators without an UMTS license who wish to offer medium-
speed mobile data services.
 EDGE is being defined for both GPRS and GSM data services.
EDGE is a redefinition of the GSM modulation and coding scheme
from GMSK to 8-PSK. It gives up to three times higher throughput
compared to GSM, using the same bandwidth. This will enable
end-user data rates of maximum 48 kbps per Time Slot for GPRS
and 28.8 kbps per TS for GSM services.
 By combining multiple TSs as with GPRS, data rates of 384 kbps
can be achieved.