unit ia, evolution

8/12/2019 UNIT Ia, Evolution

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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

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