unit ia, evolution
TRANSCRIPT
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Wireless & Mobile
Communications-1a
Inderdeep Kaur AulakhAsst. Prof. (IT)
UIET, P.U.
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Wireless Communication has evolved since Guglielmo Marconi
has sent radio signal across the Atlantic
The evolution of the wireless communications over the years islike this:
1847 Marconi sent radio signal across the Atlantic
1946 First in-car mobile phone service
1947 Bell Labs presents Cellular concepts
Evolution of Mobile Radio
Communications
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1978 CEPT (Europe Radio Club) reserve frequency
in the 900MHz Band
1981 First Cellular system-Saudi Arabia
1982 CEPT created GSM (Global System for Mobile), it is a
representative body in wireless communications
1987 GSM MoU (Memorandum of Understanding) has beenwritten there are 210 paid up bodies and 105 countries belong to
GSM main governing body
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Growth of Mobile telephony as compared to other popular invention
Fig
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Mobile Radiotelephone in the U.S
The first public mobile telephone in US was introduced in 1946.
It had a high power transmitter and a large tower to cover a distance
of over 50 km . It used 120kHz RF bandwidth in a half-duplex
mode
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During 1950s, AT&T Bell Laboratories introduced cellular radio
telephony-the concept of breaking a coverage zone into small cells
each of which reuse the portion of the spectrum
In 1983 FCC ( Federal Communications Commission) allocated 666
full-duplex channels for the U.S. - Advanced Mobile Phone System
(AMPS). This system operated in analog mode using FM or FDMA
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In 1991 U.S Digital Cellular (USDC) system hardware was installed,
thereby AMPS phased out as more users accepted digital phones.
The capacity improvement offered by USDC is three times that ofAMPS, because digital modulation, speech coding, and TDMA
are used in place of analog FM and FDMA
Later CDMA ( Code Division Multiple Access) has been developed
by Qualcomm, Inc. and has been standardized by the
Telecommunication Industry Association (TIA) as an interim
standard (IS-95)
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In 1990s, a new specialized mobile radio service (SMR) was
developed. By purchasing small groups of radio system licenses
from a large number of independent radio service providers
Motorola and Nextel has formed an extended SMR (E-SMR) in800 MHz band that could provide capacity and services similar
to cellular.
There are more than 50 Million cellular users in US today
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Mobile Radio Systems Around the World
Many mobile radio standards have been developed for wireless
systems. Some of the most common paging, cordless and cellular
standards of the world are as below.
Paging:The worlds most common paging system is the Post Office
Code Standards Advisory Group (POCSAG). This was developed
byBritish Post Office. It supports binary frequency shift keying(FSK) signaling at 512 bps, 1200 bps and 2400bps.
The new paging system FLEX and ERMES provides up to 6400bps
transmission by using 4-level modulation.
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Cordless:
CT2 and Digital European Cordless Telephone (DECT)
are the most popular cordless telephone standards throughout
Europe and Asia
CT2 systems makes use of microcells, which covers smalldistance using base stations with antenna mounted. This
system uses FSK along with 32 kbps adaptive differential
pulse code modulation (ADPCM).
DECT system accommodates data and voice system for
office and business users
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Cellular:The worlds first cellular system was implemented by the
Nippon Telephone and Telegraph company (NTT) in Japan
in 1979.
600 FM duplex channels
25kHz for each one-way link in 800MHz band
In Europe the Nordic Mobile Telephone system (NMT 450) was
developed in 1981
450 MHz Band25kHz channels
European Total Access Cellular System (ETACS) was used in1985
U.S followed USDC (U.S Digital Cellular)
Japan: used Pacific Digital Cellular (PDC) standardsGermany: used C-450 cellular standards in 1985
1990 onwards almost all of the European countries use GSM (Global
System for Mobile)- 900 MHz band. GSM has gained worldwide
acceptance as the universal standard
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Thank You