ram shanti vidya mandir

7/31/2019 Ram Shanti Vidya Mandir

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RAM SHANTI VIDYA MANDIR

PANDHURNA

Subject teacher :

Mrs. Tanvi madam

MADE BY PRITAM DIGARSE

CLASS XII

SUBJECT Computer science


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This file contains information about :-

3G

2G

gsm

cdma SIM card


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(Code-Division Multiple Access)

Code division multiple access (CDMA) is achannel access method used by various radiocommunication technologies. It should not be confusedwith themobile phone standards calledcdmaOne,

CDMA2000(the 3G evolution of cdmaOne) andWCDMA (the 3G standard used byGSM carriers),which are often referred to as simply CDMA, and useCDMA as an underlying channel access method.

One of the concepts in data communication is the ideaof allowing several transmitters to send information

simultaneously over a single communication channel.This allows several users to share a band offrequencies (seebandwidth). This concept is calledmultiple access. CDMA employsspread-spectrumtechnology and a special coding scheme (where eachtransmitter is assigned a code) to allow multiple users

to be multiplexed over the same physical channel. Bycontrast, time division multiple access(TDMA) dividesaccess bytime, whilefrequency-division multipleaccess (FDMA) divides it byfrequency. CDMA is aform ofspread-spectrum signalling, since the
http://en.wikipedia.org/wiki/Channel_access_methodhttp://en.wikipedia.org/wiki/List_of_mobile_phone_standardshttp://en.wikipedia.org/wiki/List_of_mobile_phone_standardshttp://en.wikipedia.org/wiki/IS-95http://en.wikipedia.org/wiki/IS-95http://en.wikipedia.org/wiki/CDMA2000http://en.wikipedia.org/wiki/CDMA2000http://en.wikipedia.org/wiki/3Ghttp://en.wikipedia.org/wiki/WCDMAhttp://en.wikipedia.org/wiki/GSMhttp://en.wikipedia.org/wiki/GSMhttp://en.wikipedia.org/wiki/Bandwidth_(signal_processing)http://en.wikipedia.org/wiki/Bandwidth_(signal_processing)http://en.wikipedia.org/wiki/Multiple_accesshttp://en.wikipedia.org/wiki/Spread-spectrumhttp://en.wikipedia.org/wiki/Spread-spectrumhttp://en.wikipedia.org/wiki/Spread-spectrumhttp://en.wikipedia.org/wiki/Time_division_multiple_accesshttp://en.wikipedia.org/wiki/Time_division_multiple_accesshttp://en.wikipedia.org/wiki/Timehttp://en.wikipedia.org/wiki/Timehttp://en.wikipedia.org/wiki/Frequency-division_multiple_accesshttp://en.wikipedia.org/wiki/Frequency-division_multiple_accesshttp://en.wikipedia.org/wiki/Frequency-division_multiple_accesshttp://en.wikipedia.org/wiki/Frequencyhttp://en.wikipedia.org/wiki/Frequencyhttp://en.wikipedia.org/wiki/Spread_spectrumhttp://en.wikipedia.org/wiki/Spread_spectrumhttp://en.wikipedia.org/wiki/Spread_spectrumhttp://en.wikipedia.org/wiki/Frequencyhttp://en.wikipedia.org/wiki/Frequency-division_multiple_accesshttp://en.wikipedia.org/wiki/Frequency-division_multiple_accesshttp://en.wikipedia.org/wiki/Timehttp://en.wikipedia.org/wiki/Time_division_multiple_accesshttp://en.wikipedia.org/wiki/Spread-spectrumhttp://en.wikipedia.org/wiki/Multiple_accesshttp://en.wikipedia.org/wiki/Bandwidth_(signal_processing)http://en.wikipedia.org/wiki/GSMhttp://en.wikipedia.org/wiki/WCDMAhttp://en.wikipedia.org/wiki/3Ghttp://en.wikipedia.org/wiki/CDMA2000http://en.wikipedia.org/wiki/IS-95http://en.wikipedia.org/wiki/List_of_mobile_phone_standardshttp://en.wikipedia.org/wiki/Channel_access_method


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modulated coded signal has a much higherdatabandwidth than the data being communicated.

An analogy to the problem of multiple access is a room(channel) in which people wish to talk to each othersimultaneously. To avoid confusion, people could taketurns speaking (time division), speak at differentpitches (frequency division), or speak in differentlanguages (code division). CDMA is analogous to thelast example where people speaking the same

language can understand each other, but otherlanguages are perceived as noise and rejected.Similarly, in radio CDMA, each group of users is givena shared code. Many codes occupy the same channel,but only users associated with a particular code cancommunicate.

The technology of code division multiple accesschannels has long been known. In the USSR, the first

work devoted to this subject was published in 1935 by

professor Dmitriy V. Ageev.[1]

It was shown that

through the use of linear methods, there are three

types of signal separation: frequency, time and

compensatory. The technology of CDMA was used in1957, when the young military radio engineer Leonid

Kupriyanovich in Moscow, made an experimental

model of a wearable automatic mobile phone, called
http://en.wikipedia.org/wiki/Bandwidth_(computing)http://en.wikipedia.org/wiki/Bandwidth_(computing)http://en.wikipedia.org/wiki/Noisehttp://ru.wikipedia.org/wiki/%D0%90%D0%B3%D0%B5%D0%B5%D0%B2,_%D0%94%D0%BC%D0%B8%D1%82%D1%80%D0%B8%D0%B9_%D0%92%D0%B0%D1%81%D0%B8%D0%BB%D1%8C%D0%B5%D0%B2%D0%B8%D1%87http://ru.wikipedia.org/wiki/%D0%90%D0%B3%D0%B5%D0%B5%D0%B2,_%D0%94%D0%BC%D0%B8%D1%82%D1%80%D0%B8%D0%B9_%D0%92%D0%B0%D1%81%D0%B8%D0%BB%D1%8C%D0%B5%D0%B2%D0%B8%D1%87http://en.wikipedia.org/wiki/Code_division_multiple_access#cite_note-0http://en.wikipedia.org/wiki/Code_division_multiple_access#cite_note-0http://en.wikipedia.org/wiki/Code_division_multiple_access#cite_note-0http://ru.wikipedia.org/wiki/%D0%90%D0%B3%D0%B5%D0%B5%D0%B2,_%D0%94%D0%BC%D0%B8%D1%82%D1%80%D0%B8%D0%B9_%D0%92%D0%B0%D1%81%D0%B8%D0%BB%D1%8C%D0%B5%D0%B2%D0%B8%D1%87http://en.wikipedia.org/wiki/Noisehttp://en.wikipedia.org/wiki/Bandwidth_(computing)http://en.wikipedia.org/wiki/Bandwidth_(computing)


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LK-1 by him, with a base station. LK-1 has a weight of

3 kg, 2030 km operating distance, and 2030 hours of

battery life.[2][3]

The base station, as described by the

author, could serve several customers. In 1958,

Kupriyanovich made the new experimental "pocket"

model of mobile phone. This phone weighed 0.5 kg. To

serve more customers, Kupriyanovich proposed the

device, named by him as correllator.[4][5]

In 1958, the

USSR also started the development of the "Altai"national civil mobile phone service for cars, based on

the Soviet MRT-1327 standard. The phone system

weighed 11 kg and was approximately 3 cubic meters

in size[dubious discuss]

. It was placed in the trunk of the

vehicles of high-ranking officials and used a standard

handset in the passenger compartment. The maindevelopers of the Altai system were VNIIS (Voronezh

Science Research Institute of Communications) and

GSPI (State Specialized Project Institute). In 1963 this

service started in Moscow and in 1970 Altai service

was used in 30 USSR cities
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. Individual conversations are

encoded with a pseudo-random digital sequence. CDMA

consistently provides better capacity for voice and data

communications than other commercial mobile technologies,

allowing more subscribers to connect at any given time, and it

is the common platform on which 3G technologies are built.CDMA is a form of spread spectrum, which simply means

that data is sent in small pieces over a number of the discrete

frequencies available for use at any time in the specified

range. All of the users transmit in the same wide-band chunk

of spectrum. Each users signal is spread over entire

bandwidth by a unique spreading code.

CDMA is a military technology first used

during World War II by English allies to foil German

attempts at jamming transmissions. The allies decided to


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transmit over several frequencies, instead of one, making it

difficult for the Germans to pick up the complete signal.

Because Qualcomm created communications chips for

CDMA technology, it was privy to the classified information.

Once the information became public, Qualcomm claimed

patents on the technology and became the first to

commercialize it.

CDMA (Code-Division Multiple Access) refers to any of

several protocols used in so-called second-generation (2G)and third-generation (3G) wireless communications. As the

term implies, CDMA is a form of multiplexing, which allows

numerous signals to occupy a single transmission channel,

optimizing the use of available bandwidth. The technology

isused in ultra-high-frequency (UHF) cellular telephone

systems in the 800-MHz and 1.9-GHz bands.

CDMA employs analog-

to-digital conversion (ADC) in combination with spread

spectrum technology. Audio input is first digitized into binary

elements. The frequency of the transmitted signal is then

made to vary according to a defined pattern (code), so it canbe intercepted only by a receiver whose frequency response is

programmed with the same code, so it follows exactly along

with the transmitter frequency. There are trillions of possible


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frequency-sequencing codes, which enhance privacy and

makes cloning difficult.

Third Generation

3G or 3rd generation mobile telecommunications is a

generation of standards for mobile phones andmobile

telecommunication services fulfilling the InternationalMobile Telecommunications-2000 (IMT-2000)

specifications by theInternational Telecommunication

Union.[1] Application services include wide-area wireless

voicetelephone,mobile Internetaccess, video calls and

mobile TV, all in a mobile environment.

Several telecommunications companies market wirelessmobile Internet services as 3G, indicating that the advertised

service is provided over a 3G wireless network. Services

advertised as 3G are required to meet IMT-2000 technical

standards, including standards for reliability and speed (data

transfer rates). To meet the IMT-2000 standards, a system is

required to provide peak data rates of at least 200kbit/s

(about 0.2Mbit/s). However, many services advertised as

3G provide higher speed than the minimum technical

requirements for a 3G service. Recent 3G releases, often

denoted3.5Gand3.75G, also providemobile broadband
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access of severalMbit/stosmartphones andmobile modems

in laptop computers.

The following standards are typically branded 3G: theUMTS system, first offered in 2001, standardized by

3GPP, used primarily in Europe, Japan, China (however

with a different radio interface) and other regions

predominated by GSM2Gsystem infrastructure. The

cell phones are typically UMTS and GSM hybrids.

Several radio interfaces are offered, sharing the sameinfrastructure:

o The original and most widespread radio interface is

calledW-CDMA.

o TheTD-SCDMAradio interface was

commercialised in 2009 and is only offered in

China.

o The latest UMTS release,HSPA+, can providepeak data rates up to 56 Mbit/s in the downlink in

theory (28 Mbit/s in existing services) and 22

Mbit/s in the uplink.

theCDMA2000system, first offered in 2002,

standardized by 3GPP2, used especially in North

America and South Korea, sharing infrastructure withtheIS-952G standard. The cell phones are typically

CDMA2000 and IS-95 hybrids. The latest release

EVDORev B offers peak rates of 14.7 Mbit/s

downstream.
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The above systems and radio interfaces are based onspread

spectrum radio transmission technology. While theGSM

EDGE standard ("2.9G"),DECTcordless phones and

Mobile WiMAXstandards formally also fulfill the IMT-2000 requirements and are approved as 3G standards by

ITU, these are typically not branded 3G, and are based on

completely different technologies.

A new generation of cellular standards has appeared

approximately every tenth year since1Gsystems were

introduced in 1981/1982. Each generation is characterizedby new frequency bands, higher data rates and non

backwards compatible transmission technology. The first

release of the3GPP Long Term Evolution(LTE) standard

does not completely fulfill the ITU 4G requirements called

IMT-Advanced. First release LTE is not backwards

compatible with 3G, but is a pre-4G or3.9Gtechnology,

however sometimes branded "4G" by the service providers.

Its evolutionLTE Advanced is a4G technology.WiMAX is

another technology verging on or marketed as4G.
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3G or 3rd generation mobile

telecommunications is a generation of standards for

mobile phones and mobile telecommunication services

fulfilling the International Mobile Telecommunications-

2000 (IMT-2000) specifications by the InternationalTelecommunication Union. 3G promises increased

bandwidth, up to 384 Kbps when a device is stationary of

moving at pedestrian speed.

Several telecommunications

companies market wireless mobile Internet services as 3G,

indicating that the advertised service is provided over a 3Gwireless network. Services advertised as 3G are required to

meet IMT-2000 technical standards, including standards for

reliability and speed (data transfer rates). To meet the IMT-


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2000 standards, a system is required to provide peak data

rates of at least 200 kbit/s (about 0.2 Mbit/s). However, many

services advertised as 3G provide higher speed than the

minimum technical requirements for a 3G service. Recent 3G

releases often denoted 3.5G and 3.75G also provide mobile

broadband access of several Mbit/s to smartphones and

mobile modems in laptop computers.

The bandwidth and location information

available to 3G devices gives rise to applications notpreviously available to mobile phone users. Some of the

applications are:

Mobile TV

Video on demand

Video Conferencing

Telemedicine

Location-based services

Global Positioning System (GPS)

3G refers to the third generation of mobile telephony (that is,

cellular) technology. The third generation, as the name

suggests, follows two earlier generations.


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2g(Second Generation)

2G (or 2-G) is short for

second-generation wireless telephone technology. Second

generation 2G cellular telecom networks were commercially

launched on the GSM standard in Finland by Radiolinja (now

part of Elisa Oyj) in 1991.[1] Three primary benefits of 2G

networks over their predecessors were that phone

conversations were digitally encrypted; 2G systems were

significantly more efficient on the spectrum allowing for far

greater mobile phone penetration levels; and 2G introduced

data services for mobile, starting with SMS text messages.

While digital calls tend tobe free of static and background noise, the lossy compression

used by the codecs takes a toll; the range of sound that they

convey is reduced. You will hear less of the tonality of


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someone's voice talking on a digital cellphone, but you will

hear it more clearly.

Digital voice data can be compressed and multiplexed much

more effectively than analog voice encodings through the use

of various codecs, allowing more calls to be packed into the

same amount of radio bandwidth.

Disadvantages

In less populous areas, the weaker digital signal may not

be sufficient to reach a cell tower. This tends to be a

particular problem on 2G systems deployed on higher

frequencies, but is mostly not a problem on 2G systems


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deployed on lower frequencies. National regulations

differ greatly among countries which dictate where 2G

can be deployed.

Analog has a smooth decay curve, digital a jaggedsteppy one. This can be both an advantage and a

disadvantage. Under good conditions, digital will sound

better. Under slightly worse conditions, analog will

experience static, while digital has occasionaldropouts.

As conditions worsen, though, digital will start to

completely fail, by dropping calls or being

unintelligible, while analog slowly gets worse, generally

holding a call longer and allowing at least a few words

to get through.

Advantage

While digital calls tend to be free ofstaticand

background noise, thelossy compression used by thecodecs takes a toll; the range of sound that they convey

is reduced. You will hear less of the tonality of

someone's voice talking on a digital cellphone, but you

will hear it more clearly.

Subscriber Identity Module)

A SIM card, also known as a

subscriber identity module, is a smart card that stores data for
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GSM cellular telephone subscribers. Such data includes user

identity, location and phone number, network authorization

data, personal security keys, contact lists and stored text

messages. Security features include authentication andencryption to protect data and prevent eavesdropping.

A Subscriber Identity Module (SIM) card

is a portable memory chip used mostly in cell phones that

operate on the Global System for Mobile Communications

(GSM) network. These cards hold the personal information

of the account holder, including his or her phone number,address book, text messages, and other data. When a user

wants to change phones, he or she can usually easily remove

the card from one handset and insert it into another. SIM

cards are convenient and popular with many users, and are a

key part of developing cell phone technology. A SIM is

actually a tiny computer chip that gives a cellular device itsunique phone number. It has memory, processor and ability

to interact with the user. Current SIMs typically has 16 to 64

kb of memory which helps in storing phone numbers, text

messages and other data.

A subscriber identity module or subscriber identificationmodule (SIM) is anintegrated circuitthat securely stores

theInternational Mobile Subscriber Identity (IMSI) and the

relatedkey used to identify and authenticate subscribers on
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mobiletelephonydevices (such asmobile phonesand

computers).

A SIM is embedded into a removableSIM card

, which canbe transferred between different mobile devices. SIM cards

were first made the same size as a credit card (85.60 mm

53.98 mm 0.76 mm). The development of physically-

smaller mobile devices prompted the development of a

smaller SIM card, the mini-SIM card. Mini-SIM cards have

the same thickness as full-size cards, but their length and

width are reduced to 25 mm 15 mm.

A SIM card contains its unique serial number (ICCID),

international mobile subscriber identity (IMSI), security

authentication and ciphering information, temporary

information related to the local network, a list of the services

the user has access to and two passwords: apersonal

identification number(PIN) for ordinary use and apersonalunblocking code(PUK) for PIN unlocking.
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