The document summarizes the evolution of mobile phones from early two-way radios used in vehicles to modern smartphones. It traces important developments from the first mobile radio telephone services in the 1940s-1950s to early mobile phones permanently installed in vehicles. It then covers the transition to portable bag phones and the invention of the first handheld mobile phone by Motorola in 1973. The document concludes with an overview of the four generations of cellular network technology: 1G analog, 2G digital, 2.5G packet-based data, and 3G supporting high-speed data applications.

1. DECLARATION
I, Mr. Kumar Gaurav hereby declare that this paper is the record of authentic
study carried out by me during the First semester of my MCA and has not been
submitted to any other University or Institute for the award of any degree etc.
Signature
KUMAR GAURAV
Date
1

2. ACKNOWLEDGEMENT
The successful completion of a research all incomplete without mentioning the
people who make it possible and whose guidance helped lot for the success of it.
I hereby express my gratitude and sincere thanks to Dr. M S Prasad
(Director, MCA, I.M.E.D, Bharti VidyaPeeth, Pune )for providing me all opportunity
to do this opportunity for studying this topic.
I also express my sincere thanks to Mrs. Baljeet kaur my guide,
for her timely and invaluable help and suggestion and encouragement until completion
of this study.
Signature
KUMAR GAURAV
2

3. Evolution of Mobile Phones
KUMAR GAURAV
MCA 1st sem Roll No.26 Email Id-gauravsitu@gmail.com
______________________________________________________
Statement of the problem:-
The problem is to study Evolution and development of Mobile phones .
The problem is subdivided further into following topics.
 1. Introduction to Mobile phones.
 2. History of Mobile phones.
 3. Course of development.
 4. Generations.
i. 1G
ii. 2G
iii. 2.5G
iv. 3G
v. 4G
 5. Cellular networks
 Technologies used in cellular network.
i. GSM
ii. CDMA
iii. OFDMA
iv. 3G
3

4. Table of Content
.
Content Page No.
Introduction to Mobile phones. 4
History of Mobile phones. 4
Course of development. 5
First Generations. 10
Second Generations. 10
Third generation. 11
Forth generation 13
Cellular networks 15
Technologies used in cellular network. 16
GSM 17
CDMA 24
OFDMA 26
3G 30
Summary 32
Conclusion 34
4

5. History
This history of mobile phones chronicles the development of radio telephone
technology from two-way radios in vehicles to handheld cellular communicating
devices.
In the beginning, two-way radios (known as mobile rigs) were used in vehicles such as
taxicabs, police cruisers, ambulances, and the like, but were not mobile phones because
they were not normally connected to the telephone network. Users could not dial phone
numbers from their vehicles. A large community of mobile radio users, known as the
mobileers, popularized the technology that would eventually give way to the mobile
phone. Originally, mobile phones were permanently installed in vehicles, but later
versions such as the so-called transportables or "bag phones" were equipped with a
cigarette lighter plug so that they could also be carried, and thus could be used as either
mobile or as portable two-way radios. During the early 1940s, Motorola developed a
backpacked two-way radio, the Walkie-Talkie and later developed a large hand-held
two-way radio for the US military. This battery powered "Handie-Talkie" (HT) was
about the size of a man's forearm.
 In 1866
 The first trans-Atlantic telegraph is built (not much to do with cell phones,
but a major advancement in communication nonetheless.
 In 1910
 Lars Magnus Ericsson installed a telephone in his car, although this was
not a radio telephone. While travelling across the country, he would stop at
a place where telephone lines were accessible and using a pair of long
electric wires he could connect to the national telephone network.
 In 1921
 The Police Department in Detroit, Mich. begins installing mobile radios,
operating around 2 MHz, in their squad cars. They encounter many
problems such as overcrowding on the channels and terrible interference.
5

6.  In 1934
 The U.S. Congress creates the Federal Communications Commission. They
decide who gets to use certain radio frequencies. Most channels are
reserved for emergency use and for the government. Radio is still a baby.
 In 1940’s
 the mobile radios are able to operate at 30 to 40 MHz and become much
more common between police departments, and the wealthy. Several
private companies and organizations begin using these same radios for
personal gain.
 In1945
 The first mobile-radio-telephone service is established in St. Louis, Miss.
The system is comprised of six channels that add up to 150 MHz. The
project is approved by the FCC, but due to massive interference, the
equipment barely works.
 In 1946
soviet engineers G. Shapiro and I. Zaharchenko successfully tested their
version of a radio mobile phone mounted inside a car. The device could
connect to local telephone network on a range up to 20 kilometers.
 In 1947
 Douglas H. Ring and W. Rae Young, Bell Labs engineers, proposed
hexagonal cells for mobile phones in vehicles. Philip T. Porter, also of
Bell Labs, proposed that the cell towers be at the corners of the hexagons
rather than the centers and have directional antennas that would
transmit/receive in 3 directions into 3 adjacent hexagon cells AT&T comes
out with the first radio-car-phones that can be used only on the highway
between New York and Boston; they are known as push-to-talk phones.
The system operates at frequencies of about 35 to 44 MHz, but once again
there is a massive amount of interference in the system. AT&T declares the
project a failure.
6

7.  In 1949
 The FCC authorizes the widespread use of many separate radio channels to
other carriers. They are know as Radio Common Carriers (RCC) and are
the first link between mobile phones and the telephone, rather than just
radio to radio. The RCC's are the first step toward the cellular phone
industry, which is were designed more for profit than for the general public.
 In 1956
 The first real car phones, not car radios, come into play accross the United
States. Although, the system is still using push-to-talk phones, it is an
improved version that acctually works. However, the units are big and
bulky, and require a personal radio operator to switch the calls. A simular
system appeared in Sweden a few years earlier.
 In 1964
 A new operating system is developed that operates on a single channel at
150 MHz. In essence, this removes the need for push-to-talk operators.
Now customers can dial phone numbers directly from their cars. RCC's are
finally taken seriously by the FCC as ligitimate competitors to the land-line
phone companies.
 In 1966
 Bulgaria presented the pocket mobile automatic phone RAT-0,5 combined
with a base station RATZ-10 (RATC-10) on Interorgtechnika-66
international exhibition. One base station, connected to one telephone wire
line, could serve up to 6 customers.
 In 1967
 each mobile phone had to stay within the cell area serviced by one base
station throughout the phone call. This did not provide continuity of
automatic telephone service to mobile phones moving through several cell
areas. In 1970 Amos E. Joel, Jr., another Bell Labs engineer, invented an
automatic "call handoff" system to allow mobile phones to move through
several cell areas during a single conversation without loss of conversation.
7

8.  In 1969
 The self-dialing capability is now upgraded to 450 MHz and becomes
standard in the United States. This new service is known as (IMTS)
Improved mobile telephone service.
 In 1970
 Cell phone lobbyists finally win with the FCC and get a window of 75 MHz
in the 800 MHz region, which allocated specifically for cell phones. The
FCC realizes the potential of the industry and can’t ignore it any longer.
 In 1971
 AT&T is the first company to propose a modern-day mobile-phone system
to the FCC. It involves dividing cities into “cells”. It is the first company to
do so.
 In 1973
 Dr. Martin Cooper invents the first personal handset while working for
Motorola. He takes his new invention, the Motorola Dyna-Tac., to New
York City and shows it to the public. His is credited with being the first
person to make a call on a portable mobile-phone.
Top of cellular telephone tower Dr. Martin Cooper of Motorola, made the first
US analogue mobile phone call on a larger
prototype model in 1973.
8

9. One of the first successful public commercial mobile phone networks was the ARP
network in Finland, launched in 1971. Posthumously, ARP is sometimes viewed as a
zero generation (0G) cellular network, being slightly above previous proprietary and
limited coverage networks.
The First Mobile Phone:
Motorola DynaTAC 8000X
(1983)
Motorola's DynaTAC 8000X
wasn't commercially available
until 1983, but its beginnings
can be tracked back to 1973
when the company showed off a
prototype of what would
become the world's first mobile
phone. The DynaTAC weighed
almost a kilogram, provided one
hour of battery life and stored 30
phone numbers in its
phonebook. The Motorola
DynaTAC is best known for
bring used in the 1987 movie
Wall Street, starring Michael
Douglas as corporate raider
Gordon Gecko.
 In 1975
 AT&T adapts its own cellular plan for the city of Chicago, but the FCC is
still uneasy about putting the plan into action. They have concerns about its
success.
9

10.  In 1977
 Finally cell phone testing is permitted by the FCC in Chicago. The Bell
Telephone Company gets the license; they are in a partnership with AT&T
which is a gerneral effort to battle the stubborn FCC.
 In 1981
 The FCC makes firm rules about the growing cell phone industry in
dealing with manufactures. It finally rules that Western Electric can
manufacture products for both cellular and terminal use. (Basically
they admit that they put the phone companies about 7 years behind)
First Car Phone: Nokia
Mobira Senator (1982)
In the early 1980's, the
mobile phone was best
known for its in-car use.
Nokia's Mobira Senator,
released in 1982, was the
first of its kind. A car
phone that weighed
almost 10 kilograms, the
Nokia Mobira Senator
resembled a large radio
rather than a
conventional mobile
phone.
 In 1988
 One of the most important years in cell phone evolution. The Cellular
Technology Industry Association is created and helps to make the
industry into an empire. One of its biggest contributions is when it
helped create TDMA phone technology, the most evolved cell phone
yet. It becomes available to the public in 1991
10

11. GENERATIONS OF MOBILE PHONES
First generation(1G)
1G (First Generation) is the name given to the first generation of mobile
telephone networks. These systems used analogue circuit-switched
technology, with FDMA (Frequency Division Multiple Access), and worked
mainly in the 800-900 MHz frequency bands. The networks had a low traffic
capacity, unreliable handover, poor voice quality, and poor security.
First Generation mobile phone networks were the earliest cellular systems to develop,
and they relied on a network of distributed transceivers to communicate with the mobile
phones. First Generation phones were also analogue, used for voice calls only, and their
signals were transmitted by the method of frequency modulation. These systems
typically allocated one 25 MHz frequency band for the signals to be sent from the cell
base station to the handset, and a second different 25 MHz band for signals being
returned from the handset to the base station. These bands were then split into a number
of communications channels, each of which would be used by a particular caller.
Second Generation(2G)
2G - Second Generation mobile telephone networks were
the logical next stage in the development of wireless
systems after 1G, and they introduced for the first time a
mobile phone system that used purely digital technology.
The demands placed on the networks, particularly in the
densely populated areas within cities, meant that
increasingly sophisticated methods had to be employed to
handle the large number of calls, and so avoid the risks of
interference and dropped calls at handoffs. Although many
of the principles involved in a 1G system also apply to 2G -
they both use the same cell structure - there are also differences in the way that the
signals are handled, and the 1G networks are not capable of providing the more
advanced features of the 2G systems, such as caller identity and text messaging.
11

12. In GSM 900, for example, two frequency bands of 25 MHz bandwidth are used. The
band 890-915 MHz is dedicated to uplink communications from the mobile station to
the base station, and the band 935-960 MHz is used for the downlink communications
from the base station to the mobile station. Each band is divided into 124 carrier
frequencies, spaced 200 kHz apart, in a similar fashion to the FDMA method used in 1G
systems. Then, each carrier frequency is further divided using TDMA into eight 577 uS
long "time slots", every one of which represents one communication channel - the total
number of possible channels available is therefore 124 x 8, producing a theoretical
maximum of 992 simultaneous conversations. In the USA, a different form of TDMA is
used in the system known as IS-136 D-AMPS, and there is another US system called
IS-95 (CDMAone), which is a spread spectrum code division multiple access (CDMA)
system. CDMA is the technique used in 3G systems.
2.5G
2.5G (Second Generation Enhanced) is a generic term used to
refer to a standard of wireless mobile telephone networks that
lies somewhere between 2G and 3G. The development of 2.5G
has been viewed as a stepping-stone towards 3G, which was
prompted by the demand for better data services and access to
the Internet. In the evolution of mobile communications, each
generation provides a higher data rate and additional
capabilities, and 2.5G is no exception as it is provides faster
services than 2G, but not as fast or as advanced as the newer 3G systems.
Some observers have seen 2.5G as an alternative route to 3G, but this appears to be
short-sighted as 2.5G is several times slower than the full 3G service. In technical terms
2.5G extends the capabilities of 2G systems by providing additional features, such as a
packet-switched connection (GPRS) in the TDMA-based GSM system, and enhanced
data rates (HSCSD and EDGE).
These enhancements in 2.5G systems permit data speeds of 64-144 kbps, which enables
these phones to feature web browsing, the use of navigation and navigational maps,
voice mail, fax, and the sending and receiving of large email messages.
12

13. Third Generation (3G)
3G - Third Generation mobile telephone networks are the latest stage in the development
of wireless communications technology. Significant features of 3G systems are that they
support much higher data transmission rates and offer increased capacity, which makes
them suitable for high-speed data applications as well as for the traditional voice calls.
In fact, 3G systems are designed to process data, and since voice signals are converted to
digital data, this results in speech being dealt with in much the same way as any other
form of data. Third Generation systems use packet-switching technology, which is more
efficient and faster than the traditional circuit-switched systems, but they do require a
somewhat different infrastructure to the 2G systems.
Compared to earlier mobile phones a 3G handset provides many new features, and the
possibilities for new services are almost limitless, including many popular applications
such as TV streaming, multimedia, videoconferencing, Web browsing, e-mail, paging,
fax, and navigational maps.
Japan was the first country to introduce a 3G system, which was largely because the
Japanese PDC networks were under severe pressure from the vast appetite in Japan for
digital mobile phones. Unlike the GSM systems, which developed various ways to deal
with demand for improved services, Japan had no 2.5G enhancement stage to bridge the
gap between 2G and 3G, and so the move into the new standard was seen as a solution
to their capacity problems.
It is generally accepted that CDMA is a superior transmission technology, when it is
compared to the old techniques used in GSM/TDMA. WCDMA systems make more
efficient use of the available spectrum, because the CDMA technique enables all base
stations to use the same frequency. In the WCDMA system, the data is split into separate
packets, which are then transmitted using packet switching technology, and the packets
are reassembled in the correct sequence at the receiver end by using the code that is sent
with each packet. WCDMA has a potential problem, caused by the fact that, as more
users simultaneously communicate with a base station, then a phenomenon known as
“cell breathing” can occur. This effect means that the users will compete for the finite
power of the base station’s transmitter, which can reduce the cell’s range – W-CDMA
and cdma2000 have been designed to alleviate this problem.
13

14. The operating frequencies of many 3G systems will typically use parts of the radio
spectrum in the region of approximately 2GHz (the IMT-2000 core band), which were
not available to operators of 2G systems, and so are away from the crowded frequency
bands currently being used for 2G and 2.5G networks. UMTS systems are designed to
provide a range of data rates, depending on the user’s circumstances, providing up to
144 kbps for moving vehicles (macrocellular environments), up to 384 kbps for
pedestrians (microcellular environments) and up to 2 Mbps for indoor or stationary users
(picocellular environments). In contrast, the data rates supported by the basic 2G
networks were only 9.6 kbps, such as in GSM, which was inadequate to provide any
sophisticated digital services.
Forth generation (4G)
As the limitation of the 3G, people are try to make new generation of mobile
communication, this is the 4th generation. This 4G system is more reliable,
Nowadays, some companies have started developing the 4G communication system, this
technology can have a high uplink rate up to 200Mbps, more data can transfer in the
mobile phone. So the 4G mobile can have more function such as work as the television.
Some telecommunication companies claimed that they would applied this 4G system to
the business and it will bring more convenience to people.
14

15. Technology 1G 2G 2.5G 3G 4G 5G
Beyond 4G will be 5G with incredible transmission speed with no limitation for access and zone size1
Design Begin 1970 1980 1985 1990 2000
Implementat 1984 1991 1999 2002 2010
ion
Service Analog voice, Digital voice, Higher Higher CompletelyIP
synchronous data short messages capacity, capacity, oriented,
9.6 kbps packetized broadband multimedia,
data data up to 2 Data to hundreds
Mbps of megabits
Standards AMPS, TACS, TDMA, CDMA, GPRS, WCDMA, Single standard
NMT, etc. GSM, PDC EDGE, CDMA2000
1xRTT
Data Bandwidth 1.9 kbps 14.4 kbps 384 kbps 2 Mbps 200 Mbps
Multiplexing FDMA TDMA, CDMA TDMA,CD CDMA CDMA?
MA
Core Network PSTN PSTN PSTN, Packet Internet
Packet network
Network
15

16. Cellular network Mobile phone networks
The most common example of a cellular network is a mobile phone (cell phone)
network. A mobile phone is a portable telephone which receives or makes calls through
a cell site (base station), or transmitting tower. Radio waves are used to transfer signals
to and from the cell phone. Large geographic areas (representing the coverage range of a
service provider) may be split into smaller cells to avoid line-of-sight signal loss and the
large number of active phones in an area. In cities, each cell site has a range of up to
approximately ½ mile, while in rural areas, the range is approximately 5 miles. Many
times in clear open areas, a user may receive signals from a cellsite 25 miles away. All
of the cell sites are connected to cellular telephone exchanges "switches", which connect
to a public telephone network or to another switch of the cellular company.
As the phone user moves from one cell area to another cell, the switch automatically
commands the handset and a cell site with a stronger signal (reported by each handset)
to switch to a new radio channel (frequency). When the handset responds through the
new cell site, the exchange switches the connection to the new cell site.
With CDMA, multiple CDMA handsets share a specific radio channel. The signals are
separated by using a pseudonoise code (PN code) specific to each phone. As the user
moves from one cell to another, the handset sets up radio links with multiple cell sites
(or sectors of the same site) simultaneously. This is known as "soft handoff" because,
unlike with traditional cellular technology, there is no one defined point where the phone
switches to the new cell.
Modern mobile phone networks use cells because radio frequencies are a limited, shared
resource. Cell-sites and handsets change frequency under computer control and use low
power transmitters so that a limited number of radio frequencies can be simultaneously
used by many callers with less interference.
Since almost all mobile phones use cellular technology, including GSM, CDMA, and
AMPS (analog), the term "cell phone" is used interchangeably with "mobile phone".
However, satellite phones are mobile phones that do not communicate directly with a
ground-based cellular tower, but may do so indirectly by way of a satellite.
Old systems predating the cellular principle may still be in use in places. The most
notable real hold-out is used by many amateur radio operators who maintain phone
patches in their clubs' VHF repeaters.
16

17. There are a number of different digital cellular technologies, including:
Global System for Mobile Communications (GSM), General Packet Radio Service
(GPRS), Code Division Multiple Access (CDMA), Evolution-Data Optimized (EV-
DO), Enhanced Data Rates for GSM Evolution (EDGE), 3GSM, Digital Enhanced
Cordless Telecommunications (DECT), Digital AMPS (IS-136/TDMA), and Integrated
Digital Enhanced Network (iDEN).
17

18. GSM
GSM (Global System for Mobile communications: originally from Groupe Spécial
Mobile) is the most popular standard for mobile phones in the world. Its promoter, the
GSM Association, estimates that 80% of the global mobile market uses the standard.
GSM is used by over 3 billion people across more than 212 countries and territories. Its
ubiquity makes international roaming very common between mobile phone operators,
enabling subscribers to use their phones in many parts of the world. GSM differs from
its predecessors in that both signaling and speech channels are digital, and thus is
considered a second generation (2G) mobile phone system. This has also meant that data
communication was easy to build into the system.
The ubiquity of the GSM standard has been an advantage to both consumers (who
benefit from the ability to roam and switch carriers without switching phones) and also
to network operators (who can choose equipment from any of the many vendors
implementing GSM). GSM also pioneered a low-cost (to the network carrier) alternative
to voice calls, the short message service (SMS, also called "text messaging"), which is
now supported on other mobile standards as well. Another advantage is that the standard
includes one worldwide emergency telephone number, 112. This makes it easier for
international travellers to connect to emergency services without knowing the local
emergency number.
Newer versions of the standard were backward-compatible with the original GSM
phones. For example, Release '97 of the standard added packet data capabilities, by
means of General Packet Radio Service (GPRS). Release '99 introduced higher speed
data transmission using Enhanced Data Rates for GSM Evolution (EDGE).
18

19. History
In 1982, the European Conference of Postal and Telecommunications Administrations
(CEPT) created the Groupe Spécial Mobile (GSM) to develop a standard for a mobile
telephone system that could be used across Europe.[6] In 1987, a memorandum of
understanding was signed by 13 countries to develop a common cellular telephone
system across Europe. Finally the system created by SINTEF lead by Torleiv Maseng
was selected.
In 1989, GSM responsibility was transferred to the European Telecommunications
Standards Institute (ETSI) and phase I of the GSM specifications were published in
1990. The first GSM network was launched in 1991 by Radiolinja in Finland with joint
First GSM Phone: Nokia 101 technical infrastructure maintenance from
(1992) Ericsson. By the end of 1993, over a million
subscribers were using GSM phone networks
Nokia's 101 was the world's first being operated by 70 carriers across 48 countries.
commercially available GSM
mobile phone. Paving the way for
future "candy-bar" designs, the
101 had a monochrome display, an
extendable antenna and a
phonebook that could store 99
phone numbers. It did however
lack Nokia's famous "Nokia tune"
ringtone — this wasn't introduced
until the next model in 1994.
19

20. Technical details
Cellular radio network
GSM is a cellular network, which means that mobile phones connect to it by searching
for cells in the immediate vicinity.
There are five different cell sizes in a GSM network—macro, micro, pico, femto and
umbrella cells. The coverage area of each cell varies according to the implementation
environment. Macro cells can be regarded as cells where the base station antenna is
installed on a mast or a building above average roof top level. Micro cells are cells
whose antenna height is under average roof top level; they are typically used in urban
areas. Picocells are small cells whose coverage diameter is a few dozen metres; they are
mainly used indoors. Femtocells are cells designed for use in residential or small
business environments and connect to the service provider’s network via a broadband
internet connection. Umbrella cells are used to cover shadowed regions of smaller cells
and fill in gaps in coverage between those cells.
Cell horizontal radius varies depending on antenna height, antenna gain and propagation
conditions from a couple of hundred meters to several tens of kilometres. The longest
distance the GSM specification supports in practical use is 35 kilometres (22 mi). There
are also several implementations of the concept of an extended cell, where the cell
radius could be double or even more, depending on the antenna system, the type of
terrain and the timing advance.
Indoor coverage is also supported by GSM and may be achieved by using an indoor
picocell base station, or an indoor repeater with distributed indoor antennas fed through
power splitters, to deliver the radio signals from an antenna outdoors to the separate
indoor distributed antenna system. These are typically deployed when a lot of call
capacity is needed indoors; for example, in shopping centers or airports. However, this is
not a prerequisite, since indoor coverage is also provided by in-building penetration of
the radio signals from any nearby cell.
20

21. The modulation used in GSM is Gaussian minimum-shift keying (GMSK), a kind of
continuous-phase frequency shift keying. In GMSK, the signal to be modulated onto the
carrier is first smoothed with a Gaussian low-pass filter prior to being fed to a frequency
modulator, which greatly reduces the interference to neighboring channels (adjacent
channel interference).
Interference with audio devices
Some audio devices are susceptible to radio frequency interference (RFI), which could
be mitigated or eliminated by use of additional shielding and/or bypass capacitors in
these audio devices. However, the increased cost of doing so is difficult for a designer to
justify.
It is a common occurrence for a nearby GSM handset to induce a "dit, dit di-dit, dit di-
dit, dit di-dit" audio output on PAs, wireless microphones, home stereo systems,
televisions, computers, cordless phones, and personal music devices. When these audio
devices are in the near field of the GSM handset, the radio signal is strong enough that
the solid state amplifiers in the audio chain act as a detector. The clicking noise itself
represents the power bursts that carry the TDMA signal. These signals have been known
to interfere with other electronic devices, such as car stereos and portable audio players.
This also depends on the handset's design, and its conformance to strict rules and
regulations allocated by the US body, the FCC, in part 15 of its rules and regulations
pertaining to interference with electronic devices.
GSM frequencies
GSM networks operate in a number of different frequency ranges (separated into GSM
frequency ranges for 2G and UMTS frequency bands for 3G). Most 2G GSM networks
operate in the 900 MHz or 1800 MHz bands. Some countries in the Americas (including
Canada and the United States) use the 850 MHz and 1900 MHz bands because the 900
and 1800 MHz frequency bands were already allocated. Most 3G GSM networks in
Europe operate in the 2100 MHz frequency band.
The rarer 400 and 450 MHz frequency bands are assigned in some countries where these
frequencies were previously used for first-generation systems.
21

22. GSM-900 uses 890–915 MHz to send information from the mobile station to the base
station (uplink) and 935–960 MHz for the other direction (downlink), providing 125 RF
channels (channel numbers 0 to 124) spaced at 200 kHz. Duplex spacing of 45 MHz is
used.
In some countries the GSM-900 band has been extended to cover a larger frequency
range. This 'extended GSM', E-GSM, uses 880–915 MHz (uplink) and 925–960 MHz
(downlink), adding 50 channels (channel numbers 975 to 1023 and 0) to the original
GSM-900 band. Time division multiplexing is used to allow eight full-rate or sixteen
half-rate speech channels per radio frequency channel. There are eight radio timeslots
(giving eight burst periods) grouped into what is called a TDMA frame. Half rate
channels use alternate frames in the same timeslot. The channel data rate for all 8
channels is 270.833 kbit/s, and the frame duration is 4.615 ms.
The transmission power in the handset is limited to a maximum of 2 watts in
GSM850/900 and 1 watt in GSM1800/1900.
.
Network structure
22

23. The structure of a GSM network
The network behind the GSM seen by the customer is large and complicated in order to
provide all of the services which are required. It is divided into a number of sections and
these are each covered in separate articles.
• the Base Station Subsystem (the base stations and their controllers).
• the Network and Switching Subsystem (the part of the network most similar to a
fixed network). This is sometimes also just called the core network.
• the GPRS Core Network (the optional part which allows packet based Internet
connections).
• all of the elements in the system combine to produce many GSM services such as
voice calls and SMS.
Subscriber Identity Module (SIM)
One of the key features of GSM is the Subscriber Identity Module, commonly known as
a SIM card. The SIM is a detachable smart card containing the user's subscription
information and phone book. This allows the user to retain his or her information after
switching handsets. Alternatively, the user can also change operators while retaining the
handset simply by changing the SIM. Some operators will block this by allowing the
phone to use only a single SIM, or only a SIM issued by them; this practice is known as
SIM locking, and is illegal in some countries.
In Australia, North America and Europe many operators lock the mobiles they sell. This
is done because the price of the mobile phone is typically subsidised with revenue from
subscriptions, and operators want to try to avoid subsidising competitor's mobiles. A
subscriber can usually contact the provider to remove the lock for a fee, utilize private
services to remove the lock, or make use of ample software and websites available on
the Internet to unlock the handset themselves. While most web sites offer the unlocking
for a fee, some do it for free. The locking applies to the handset, identified by its
International Mobile Equipment Identity (IMEI) number, not to the account (which is
identified by the SIM card).
In some countries such as Bangladesh, Belgium, Costa Rica, Indonesia, Malaysia, Hong
Kong and Pakistan, all phones are sold unlocked. However, in Belgium, it is unlawful
for operators there to offer any form of subsidy on the phone's price. This was also the
case in Finland until April 1, 2006, when selling subsidized combinations of handsets
and accounts became legal, though operators have to unlock phones free of charge after
a certain period (at most 24 months).
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24. GSM security
GSM was designed with a moderate level of security. The system was designed to
authenticate the subscriber using a pre-shared key and challenge-response.
Communications between the subscriber and the base station can be encrypted. The
development of UMTS introduces an optional USIM, that uses a longer authentication
key to give greater security, as well as mutually authenticating the network and the user
- whereas GSM only authenticates the user to the network (and not vice versa). The
security model therefore offers confidentiality and authentication, but limited
authorization capabilities, and no non-repudiation. GSM uses several cryptographic
algorithms for security. The A5/1 and A5/2 stream ciphers are used for ensuring over-
the-air voice privacy. A5/1 was developed first and is a stronger algorithm used within
Europe and the United States; A5/2 is weaker and used in other countries. Serious
weaknesses have been found in both algorithms: it is possible to break A5/2 in real-time
with a ciphertext-only attack, and in February 2008, Pico Computing, Inc revealed its
ability and plans to commercialize FPGAs that allow A5/1 to be broken with a rainbow
table attack. The system supports multiple algorithms so operators may replace that
cipher with a stronger one…
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25. CDMA
Code division multiple access (CDMA) is a channel access method utilized by various
radio communication technologies. It should not be confused with the mobile phone
standards called cdmaOne and CDMA2000 (which are often referred to as simply
"CDMA"), which use CDMA as an underlying channel access method.
One of the basic concepts in data communication is the idea of allowing several
transmitters to send information simultaneously over a single communication channel.
This allows several users to share a bandwidth of different frequencies. This concept is
called multiplexing. CDMA employs spread-spectrum technology and a special coding
scheme (where each transmitter is assigned a code) to allow multiple users to be
multiplexed over the same physical channel. By contrast, time division multiple access
(TDMA) divides access by time, while frequency-division multiple access (FDMA)
divides it by frequency. CDMA is a form of "spread-spectrum" signaling, since the
modulated coded signal has a much higher data bandwidth than the data being
communicated.
An analogy to the problem of multiple access is a room (channel) in which people wish
to communicate with each other. To avoid confusion, people could take turns speaking
(time division), speak at different pitches (frequency division), or speak in different
languages (code division). CDMA is analogous to the last example where people
speaking the same language can understand each other, but not other people. Similarly,
in radio CDMA, each group of users is given a shared code. Many codes occupy the
same channel, but only users associated with a particular code can understand each
other.
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26. Uses
A CDMA mobile phone
• One of the early applications for code division multiplexing—predating, and
distinct from cdmaOne—is in GPS.
• The Qualcomm standard IS-95, marketed as cdmaOne.
• The Qualcomm standard IS-2000, known as CDMA2000. This standard is used
by several mobile phone companies, including the Globalstar satellite phone
network.
• CDMA has been used in the OmniTRACS satellite system for transportation
logistics.
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27. OFDMA
Orthogonal Frequency-Division Multiple Access (OFDMA) is a multi-user version of
the popular Orthogonal frequency-division multiplexing (OFDM) digital modulation
scheme. Multiple access is achieved in OFDMA by assigning subsets of subcarriers to
individual users as shown in the illustration below. This allows simultaneous low data
rate transmission from several users.
Claimed advantages over CDMA
• OFDM can combat multipath interference with more robustness and less
complexity.
• OFDMA can achieve a higher MIMO spectral efficiency due to providing flatter
frequency channels than a CDMA RAKE receiver can.
• No Cell size breathing as more users connect
Claimed OFDMA Advantages
• Flexibility of deployment across various frequency bands with little needed
modification to the air interface.
• Averaging interferences from neighboring cells, by using different basic carrier
permutations between users in different cells.
• Interferences within the cell are averaged by using allocation with cyclic
permutations.
• Enables orthogonality in the uplink by synchronizing users in time and frequency
Enables Single Frequency Network coverage, where coverage problem exists and gives
excellent coverage
• Enables adaptive carrier allocation in multiplication of 23 carriers = nX23 carriers
up to 1587 carriers (all data carriers).
• Offers Frequency diversity by spreading the carriers all over the used spectrum.
• Offers Time diversity by optional interleaving of carrier groups in time.
• Using the cell capacity to the utmost by adaptively using the highest modulation a
user can use, this is allowed by the gain added when less carriers are allocated (up
to 18dB gain for 23 carrier allocation instead of 1587 carriers), therefore gaining
in overall cell capacity.
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28. Recognised disadvantages of OFDMA
• Higher sensitivity to frequency offsets and phase noise.
• Asynchronous data communication services such as web access are characterized
by short communication bursts at high data rate. Few users in a base station cell
are transferring data simultaneously at low constant data rate.
• The complex OFDM electronics, including the FFT algorithm and forward error
correction, is constantly active independent of the data rate, which is inefficient
from power consumption point of view, while OFDM combined with data packet
scheduling may allow that the FFT algorithm hibernates during certain time
intervals.
• The OFDM diversity gain, and resistance to frequency-selective fading, may
partly be lost if very few sub-carriers are assigned to each user, and if the same
carrier is used in every OFDM symbol. Adaptive sub-carrier assignment based on
fast feedback information about the channel, or sub-carrier frequency hopping, is
therefore desirable.
• Dealing with co-channel interference from nearby cells is more complex in
OFDM than in CDMA. It would require dynamic channel allocation with
advanced coordination among adjacent base stations.
• The fast channel feedback information and adaptive sub-carrier assignment is
more complex than CDMA fast power control.
Characteristics and principles of operation
• Based on feedback information about the channel conditions, adaptive user-to-
subcarrier assignment can be achieved. If the assignment is done sufficiently fast,
this further improves the OFDM robustness to fast fading and narrow-band
cochannel interference, and makes it possible to achieve even better system
spectral efficiency.
• Different number of sub-carriers can be assigned to different users, in view to
support differentiated Quality of Service (QoS), i.e. to control the data rate and
error probability individually for each user.
• OFDMA resembles code division multiple access (CDMA) spread spectrum,
where users can achieve different data rates by assigning a different code
spreading factor or a different number of spreading codes to each user.
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29. • OFDMA can be seen as an alternative to combining OFDM with time division
multiple access (TDMA) or time-domain statistical multiplexing, i.e. packet mode
communication. Low-data-rate users can send continuously with low transmission
power instead of using a "pulsed" high-power carrier. Constant delay, and shorter
delay, can be achieved.
• OFDMA can also be described as a combination of frequency domain and time
domain multiple access, where the resources are partitioned in the time-frequency
space, and slots are assigned along the OFDM symbol index as well as OFDM
sub-carrier index.
• OFDMA is considered as highly suitable for broadband wireless networks, due to
advantages including scalability and MIMO-friendliness, and ability to take
advantage of channel frequency selectivity.[1]
• In spectrum sensing cognitive radio, OFDMA is a possible approach to filling free
radio frequency bands adaptively. Timo A. Weiss and Friedrich K. Jondral of the
University of Karlsruhe proposed a spectrum Pooling system in which free bands
sensed by nodes were immediately filled by OFDMA subbands.
Usage
OFDMA is used in:
• the mobility mode of the IEEE 802.16 Wireless MAN standard, commonly
referred to as WiMAX,
• the IEEE 802.20 mobile Wireless MAN standard, commonly referred to as
MBWA,
• the downlink of the 3GPP Long Term Evolution (LTE) fourth generation mobile
broadband standard. The radio interface was formerly named High Speed OFDM
Packet Access (HSOPA), now named Evolved UMTS Terrestrial Radio Access
(E-UTRA).
• the Qualcomm Flarion Technologies Mobile Flash-OFDM
• the now defunct Qualcomm/3GPP2 Ultra Mobile Broadband (UMB) project,
intended as a successor of CDMA2000, but replaced by LTE.
OFDMA is also a candidate access method for the IEEE 802.22 Wireless Regional Area
Networks (WRAN). The project aims at designing the first cognitive radio based
standard operating in the VHF-low UHF spectrum (TV spectrum).
The term "OFDMA" is claimed to be a registered trademark by Runcom Technologies
Ltd., with various other claimants to the underlying technologies through patents.
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30. 3G
International Mobile Telecommunications-2000 (IMT-2000), better known as 3G or 3rd
Generation, is a family of standards for mobile telecommunications defined by the
International Telecommunication Union, which includes GSM, EDGE, UMTS, and
CDMA2000 as well as DECT and WiMAX. Services include wide-area wireless voice
telephone, video calls, and wireless data, all in a mobile environment. Compared to 2G
and 2.5G services, 3G allows simultaneous use of speech and data services and higher
data rates (up to 14.0 Mbit/s on the downlink and 5.8 Mbit/s on the uplink with HSPA+).
Thus, 3G networks enable network operators to offer users a wider range of more
advanced services while achieving greater network capacity through improved spectral
efficiency.
The International Telecommunication Union (ITU) defined the third generation (3G) of
mobile telephony standards – IMT-2000 – to facilitate growth, increase bandwidth, and
support more diverse applications. For example, GSM (the current most popular cellular
phone standard) could deliver not only voice, but also circuit-switched data at download
rates up to 14.4 kbps. But to support mobile multimedia applications, 3G had to deliver
packet-switched data with better spectral efficiency, at far greater bandwidths
The first pre-commercial 3G network was launched by NTT DoCoMo in Japan branded
FOMA, in May 2001 on a pre-release of W-CDMA technology. The first commercial
launch of 3G was also by NTT DoCoMo in Japan on October 1, 2001, although it was
initially somewhat limited in scope; broader availability was delayed by apparent
concerns over reliability. The second network to go commercially live was by SK
Telecom in South Korea on the 1xEV-DO technology in January 2002. By May 2002
the second South Korean 3G network was by KTF on EV-DO and thus the Koreans
were the first to see competition among 3G operators.
The first commercial United States 3G network was by Monet Mobile Networks, on
CDMA2000 1x EV-DO technology, but this network provider later shut down
operations. The second 3G network operator in the USA was Verizon Wireless in
October 2003 also on CDMA2000 1x EV-DO. AT&T Mobility is also a true 3G
network, having completed its upgrade of the 3G network to HSUPA.
In December 2007, 190 3G networks were operating in 40 countries and 154 HSDPA
networks were operating in 71 countries, according to the Global Mobile Suppliers
Association (GSA). In Asia, Europe, Canada and the USA, telecommunication
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31. companies use W-CDMA technology with the support of around 100 terminal designs to
operate 3G mobile networks.
In Europe, mass market commercial 3G services were introduced starting in March 2003
by 3 (Part of Hutchison Whampoa) in the UK and Italy. The European Union Council
suggested that the 3G operators should cover 80% of the European national populations
by the end of 2005.
Roll-out of 3G networks was delayed in some countries by the enormous costs of
additional spectrum licensing fees. In many countries, 3G networks do not use the same
radio frequencies as 2G, so mobile operators must build entirely new networks and
license entirely new frequencies; an exception is the United States where carriers operate
3G service in the same frequencies as other services. The license fees in some European
countries were particularly high, bolstered by government auctions of a limited number
of licenses and sealed bid auctions, and initial excitement over 3G's potential. Other
delays were due to the expenses of upgrading equipment for the new systems.
China announced in May 2008, that the telecoms sector was re-organized and three 3G
networks would be allocated so that the largest mobile operator, China Mobile, would
retain its GSM customer base. China Unicom would retain its GSM customer base but
relinquish its CDMA2000 customer base, and launch 3G on the globally leading
WCDMA (UMTS) standard. The CDMA2000 customers of China Unicom would go to
China Telecom, which would then launch 3G on the CDMA 1x EV-DO standard. This
meant that China would have all three main cellular technology 3G standards in
commercial use. Finally in January 2009, Ministry of industry and Information
Technology of China has awarded licenses of all three standards.TD-SCDMA to China
Mobile, WCDMA to China Unicom and CDMA2000 to China Telecom.
Still, several developing countries have not awarded 3G licenses and customers await
3G services. China delayed its decisions on 3G for many years, mainly because of their
Government's delay in establishing well defined standards.[12]
The first African use of 3G technology was a 3G videocall made in Johannesburg on the
Vodacom network in November 2004. The first commercial launch of 3G in Africa was
by EMTEL in Mauritius on the W-CDMA standard. In north African Morocco in late
March 2006, a 3G service was provided by the new company Wana.
T-Mobile, a major Telecommunication services provider has recently rolled out a list of
over 120 U.S. cities which will be provided with 3G Network coverage in the year 2009.
In 2008, India entered into 3G Mobile arena with the launch of 3G enabled Mobile
services by Mahanagar Telephone Nigam Limited (MTNL). MTNL is the first Mobile
operator in India to launch 3G services.
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32. With so much ease it is surely a desirable possession. But ever since it was launched,
every country faced similar problems in introducing it as India does today – its
installation being the main one. It requires humungous amounts to set up infrastructure
for 3G technology. Not many telecom companies have the ability to incur such huge
expenditures to lay up its networks across the nation. India faces this problem
currently/today. Even if they decide to set up networks, it may not be far reaching and
located everywhere. Then, how will it serve to be better than laptop enabled broadband?
How will it help one stay connected when traveling? And how will it offer continued
facility at all times and places? Apart from this, licensing a 3G technology remains an
impediment. So, it’s not just the expenditure on infrastructure but also on license, which
sums up/amounts to be undesirably mammoth.
Talking for the benefit of users, even if one or two of the telecom companies
successfully launch 3G technology, its growth and usage will still remain minimal. That
is because, its strongest feature, video conferencing can be undertaken only when the
others too are using smart phones. If even one of the persons participating in the
interaction does not possess it, it will not be possible to interact with him. This will be
the weakest point as not everybody would want to take up connections of the companies
that are offering 3G technology. To make things tougher, a 3G enabled handset is
different from the other handsets available in the market and it’s more expensive than a
normal 2G enabled one. So, to enjoy the benefits of 3G technology, one will first have to
condemn the older handset and then incur huge amounts of losses to buy a smartphone.
Not just this, its mobile services are also very highly priced. Internet access is pretty
expensive too.
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33. Summary
The Mobile phone which we used today is a result of long course of development .as we
know that “Rome was not built in a day.” Likewise the Mobile phone, its technology
and cellular networking has a glorious course of continuous research work and
development. History of mobile phone include the first Two-way radios (known as
mobile rigs) which were used in vehicle to the present scenario in which we have touch
screen phones .
Cellular Networking includes the development from the first car phone to the
series which include generations of mobile phones. And the technologies like GSM,
CDMA, and 3G.
First Generation mobile phone networks includes FDMA technology. Analog system
designed for voice only communication. 1G system is almost extinct now.
Second Generation (2G) Use GSM and IS-95 CDMA technologies and they introduced
for the first time a mobile phone system that used purely digital technology.
Third Generation mobile telephone networks are the latest stage in the development of
wireless communications technology.
4G communication system is still under development. It will Combined the technologies
of Wireless local area network (will be introduced soon) and 3G.
Then comes the Different digital cellular technologies like GSM, CDMA and OFDMA.
GSM (Global System for Mobile communications) is a second generation cellular
standard developed to cater voice services and data delivery using digital modulation.
CDMA (Code division multiple access) is a high-speed wireless data and voice network
solution for low-cost, easy to deploy, high-performance services, that address the needs
of governments, operators and subscribers.
Orthogonal Frequency-Division Multiple Access (OFDMA) is a multi-user version of
the popular Orthogonal frequency-division multiplexing (OFDM) digital modulation
scheme. Multiple accesses are achieved in OFDMA by assigning subsets of subcarriers
to individual users as shown in the illustration below. This allows simultaneous low data
rate transmission from several users.
33

34. International Mobile Telecommunications-2000 (IMT-2000), better known as 3G or 3rd
Generation, is a family of standards for mobile telecommunications defined by the
International Telecommunication Union,3G Wireless Systems are the new generation of
systems that offer high bandwidth and support digital voice along with multimedia and
global roaming. It remains to be seen how much of the promised features and
applications are actually implemented in today’s economy.
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35. Conclusion
3G cellular wireless technologies provide much greater levels of functionality and
flexibility than previous generations. 3G offers improved RF spectral efficiency and
higher bit rates. While the focus for the first 3G systems appears to be voice and
limited data services, 3G is also expected to become a significant Internet access
technology. As always, equipment manufacturers that are early to market will gain a
big jump on the competition. However, performance of 3G systems will be just as
important as a competitive differentiator. The only way to achieve both objectives
will be through a carefully planned and streamlined test and verification strategy.
Understanding, these pros and cons, India still remains incompetent to grow in terms
of 3G technology. Progress is on and companies have started to introduce 3G in
India. However, it does only when every communication company decides to take
this up then its success can be identified. For the time being, this service does not
seem suitable for all the income groups and remains confined only to high-earning
persons due to its expensive handsets and services. Nonetheless, prices will be
lowered once competition is increased by more and more companies introducing it.
We are waiting for the same to happen.
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