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INTRODUCTION TO MOBILE PHONE

A mobile phone (also known as a cellular phone, cell phone, hand phone, or simply a phone) is a phone that can make and receive telephone calls over a radio link while moving around a widegeographic area. It does so by connecting to a cellular network  provided by a mobile phone

operator, allowing access to the  public telephone network. By contrast, a cordless telephone isused only within the short range of a single, private base station.

In addition to telephony, modern mobile phones also support a wide variety of other servicessuch as text messaging,  MMS,  email,  Internet access, short-range wireless communications(infrared, Bluetooth), business applications, gaming, and photography. Mobile phones that offerthese and more general computing capabilities are referred to as a Smartphone. 

The first hand-held cell phone was demonstrated by John F. Mitchell and Dr. Martin Cooper ofMotorola in 1973, using a handset weighing around 4.4 pounds (2 kg). In 1983, the Dyna TAC8000x was the first to be commercially available. From 1990 to 2011, worldwide mobile phonesubscriptions grew from 12.4 million to over 6 billion, penetrating about 87% of the global population and reaching the  bottom of the economic pyramid.  In 2013, the top cell phonemanufacturers were Samsung, Nokia, Apple Inc., and LG. 

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The mobile phone can be used to communicate over long distances without wires. It works bycommunicating with a nearby base station (also called a "cell site") which connects it to the main phone network. As the mobile phone moves around, if the mobile phone gets too far away fromthe cell it is connected to, that cell sends a message to another cell to tell the new cell to takeover the call. This is called a "hand off," and the call continues with the new cell the phone is

connected to. The hand-off is done so well and carefully that the user will usually never evenknow that the call was transferred to another cell.

As mobile phones became more popular, they began to cost less money, and more people couldafford them. Monthly plans became available for rates as low as US$30 or US$40 a month. Cell phones have become so cheap to own that they have mostly replaced  pay phones and phone booths except for  urban areas with many people.

History & Evolution of Mobile Phones

Mobile phones in the 1950s through 1970s were large and heavy, and most were built into cars.In the late 20th century technology improved so people could carry their phones easily.

Although Dr. Martin Cooper from Motorola made the first call using a mobile phone in 1973, itdid not use the type of cellular mobile phone network that we use today.

The first mobile phone networks were created in the late 1970s in Japan. Now almost all  urbanareas, and many country areas, are covered by mobile phone networks.

Early predecessors of cellular phones included analog radio communications from ships and

trains. The race to create truly portable telephone devices began after World War II, withdevelopments taking place in many countries. The advances in mobile telephony have been

traced in successive generations from the early "0G" (zero generation) services like the Bell

System's Mobile Telephone Service and its successor, Improved Mobile Telephone Service. 

These "0G" systems were not cellular, supported few simultaneous calls, and were very

expensive.

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The first handheld mobile cell phone was demonstrated by Motorola in 1973. The first

commercial automated cellular network was launched in Japan by NTT in 1979. In 1981, this

was followed by the simultaneous launch of the  Nordic Mobile Telephone (NMT) system in

Denmark, Finland, Norway and Sweden.[9] Several other countries then followed in the early to

mid-1980s. These first generation ("1G") systems could support far more simultaneous calls, but

still used analog technology.

In 1991, the second generation (2G)  digital   cellular technology was launched in Finland byRadiolinja on the GSM standard, which sparked competition in the sector, as the new operatorschallenged the incumbent 1G network operators.

Ten years later, in 2001, the third generation (3G) was launched in Japan by NTT Do Como onthe WCDMA standard. This was followed by 3.5G, 3G+ or turbo 3G enhancements based on thehigh-speed packet access (HSPA) family, allowing UMTS networks to have higher data transferspeeds and capacity.

By 2009, it had become clear that, at some point, 3G networks would be overwhelmed by thegrowth of bandwidth-intensive applications like streaming media. Consequently, the industry

 began looking to data-optimized 4th-generation technologies, with the promise of speedimprovements up to 10-fold over existing 3G technologies. The first two commercially availabletechnologies billed as 4G were the WiMAX standard (offered in the U.S. by Sprint) and the LTEstandard, first offered in Scandinavia by TeliaSonera. 

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FEATURES OF A MOBILE PHONE

The features of  mobile phones are the set of capabilities, services and applications that they offer

to their users. Low-end mobile phones are often referred to as feature phones, and offer basic

telephony. Handsets with more advanced computing ability through the use of native software

applications became known as smart phones. 

General features:-

The common components found on all phones are:

  A battery, providing the power source for the phone functions.

  An input mechanism to allow the user to interact with the phone. The most common input

mechanism is a keypad, but touch screens are also found in some high-end smartphones.

  Basic mobile phone services to allow users to make calls and send text messages.

  All GSM phones use a SIM card to allow an account to be swapped among devices.

Some CDMA devices also have a similar card called a R-UIM. 

  Individual GSM, WCDMA, iDEN and some satellite phone devices are uniquely

identified by an International Mobile Equipment Identity (IMEI) number.

Standard Services:-

All mobile phones are designed to work on cellular networks and contain a standard set of

services that allow phones of different types and in different countries to communicate with eachother. However, they can also support other features added by various manufacturers over theyears:

  Roaming which permits the same phone to be used in multiple countries, providing that

the operators of both countries have a roaming agreement. 

  Send and receive data and faxes (if a computer is attached), access WAP services, and

 provide full Internet access using technologies such as GPRS. 

  Applications like a clock, alarm, calendar and calculator and a few games.

 

Sending and receiving pictures and videos through MMS, and for short distances with

e.g. Bluetooth. 

  GPS receivers integrated or connected (i.e. using Bluetooth) to cell phones, primarily to

aid in dispatching emergency responders and road tow truck services. This feature is

generally referred to as E911. 

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  Push to talk, available on some mobile phones, is a feature that allows the user to be

heard only while the talk button is held, similar to a walkie-talkie. 

Inner Circuitry of a Mobile Phone:-

1. Antenna Switch: It is found in the Network Section of a mobile phone and is made up ofmetal and non-metal. In GSM sets it is found in white color and in CDMA sets it is found ingolden metal. 

Work : It searches network and passes forward after tuning.

Faults: If the Antenna Switch is faulty then there will be no network in the mobile phone.

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2. P.F.O: It is found near the Antenna Switch in the Network Section of the PCB of Mobile

Phone. It is also called P.A (Power Amplifier) and Band Pass Filter.

Work : It filters and amplifies network frequency and selects the home network.

Faults: If the PFO is faulty then there will be no network in the mobile phone. If it gets shortthen the mobile phone will get dead.

3. RF IC / Hagar / Network IC: This electronic component found near the PFO in the NetworkSection of a Mobile Phone. It is also called RF signal processor.

Work : It works as transmitter and receiver of audio and radio waves according to the instructionfrom the CPU.

Faults: If the RF IC is faulty then there will be problem with network in the mobile phone.Sometimes the mobile phone can even get dead.

4. 26 MHz Crystal Oscillator: It is found near the PFO in the Network Section of a MobilePhone. It is also called Network Crystal. It is made up of metal.

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Work : It creates frequency during outgoing calls.

Faults: If this crystal is faulty then there will be no outgoing call and no network in the mobile phone.

5. VCO: It is found near the Network IC in the Network Section of a Mobile Phone.

Work : It sends time, date and voltage to the RF IC / Hager and the CPU. It also createsfrequency after taking command from the CPU.

Faults: If it is faulty then there will be no network in the mobile phone and it will display “Call

End” or “Call Failed”. 

6. RX Filter: It is found in the Network Section of a Mobile Phone.

Work : It filters frequency during incoming calls.

Faults: If it is faulty then there will network problem during incoming calls.

7. TX Filter: It is found in the Network Section of a Mobile Phone.

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Work : It filters frequency during outgoing calls.

Faults: If it is faulty then there will network problem during outgoing calls.

8. ROM: It is found in the Power Section of a Mobile Phone.

Work : It loads current operating program in a Mobile Phone.

Faults: If ROM is faulty then there will software problem in the mobile phone and the set willget dead.

9. RAM: It is found in the Power Section of a Mobile Phone.

Work : It sends and receives commands of the operating program in a mobile phone.

Faults: If RAM is faulty then there will be software problem in the mobile phone and it will getfrequently get hanged and the set can even get dead.

10. Flash IC: It is found in the Power Section of a Mobile Phone. It is also called EEPROM IC,Memory IC, RAM IC and ROM IC.

Work : Software of the mobile phone is installed in the Flash IC.

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Faults: If Flash IC is faulty then the mobile phone will not work properly and it can even getdead.

11. Power IC: It is found in the Power Section of a Mobile Phone. There are many smallcomponents mainly capacitor around this IC. RTC is near the Power IC.

Work : It takes power from the battery and supplies to all other parts of a mobile phone.

Faults: If Power IC is faulty then the set will get dead.

12. Charging IC: It is found in the Power Section near R22.

Work : It takes current from the charger and charges the battery.

Faults: If Charging IC is faulty then the set will not get charged. If the Charging IC is short thenthe set will get dead.

13. RTC (Simple Silicon Crystal): It is Real Time Clock and is found in the Power Section nearPower IC. It is made up of either metal or non-metal. It is of long shape.

Work : It helps to run the date and time in a mobile phone.

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Faults: If RTC is faulty then there will be no date or time in the mobile phone and the set caneven get dead.

14. CPU: It is found in the Power Section. It is also called MAD IC, RAP IC and UPP. It is thelargest IC on the PCB of a Mobile Phone and it looks different from all other ICs.

Work : It controls all sections of a mobile phone.

Faults: If CPU is faulty then the mobile phone will get dead.

15. Logic IC / UI IC: It is found in any section of a mobile phone. It has 20 pins or legs. It isalso called UI IC and Interface IC.

Work : It controls Ringer, Vibrator and LED of a mobile phone.

Faults: If Logic IC / UI IC is faulty then Ringer, Vibrator and LED of mobile phone will norwork properly.

16. Audio IC: It is found in Power Section of a mobile phone. It is also called Cobba IC andMelody IC.

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Work : It controls Speaker and Microphone of a mobile phone.

Faults: If Audio IC is faulty then Speaker and Microphone of a mobile phone will not work andthe set can even get dead.

SIM card (Subscriber Identity Module)

A subscriber identity module or subscriber identification module (SIM) is an integratedcircuit that securely stores the international mobile subscriber identity (IMSI) and the related key

used to identify and authenticate subscribers on mobile telephony devices (such as mobile phones and computers).

A SIM circuit is embedded into a removable plastic card. This plastic card is called a "SIM card"and can be transferred between different mobile devices. A SIM card follows certain smart cardstandards. 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 ofsmaller SIM cards where the quantity of card surrounding the integrated circuit is reduced.

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A SIM card contains its unique serial number (ICCID), international mobile subscriber identity(IMSI), security authentication and ciphering information, temporary information related to thelocal network, a list of the services the user has access to and two passwords: a personalidentification number (PIN) for ordinary use and a personal unblocking code (PUK) for PINunlocking.

SIM cards store network-specific information used to authenticate and identify subscribers on thenetwork. The most important of these are the ICCID, IMSI, Authentication Key (Ki), Local AreaIdentity (LAI) and Operator-Specific Emergency Number. The SIM also stores other carrier-specific data such as the SMSC (Short Message Service Center) number, Service Provider Name(SPN), Service Dialing Numbers (SDN), Advice-Of-Charge parameters and Value AddedService (VAS) applications. (Refer to GSM 11.11.)

SIM cards can come in various data capacities, from 32 KB to at least 128 KB. All allow amaximum of 250 contacts to be stored on the SIM, but while the 32 KB has room for 33 Mobile Network Codes (MNCs) or "network identifiers", the 64 KB version has room for 80 MNCs.

This is used by network operators to store information on preferred networks, mostly used whenthe SIM is not in its home network but is roaming. The network operator that issued the SIMcard can use this to have a phone connect to a preferred network, in order to make use of the best price and/or quality network instead of having to pay the network operator that the phone 'saw'first. This does not mean that a phone containing this SIM card can connect to a maximum ofonly 33 or 80 networks, but it means that the SIM card issuer can specify only up to that numberof preferred networks; if a SIM is outside these preferred networks it will use the first or bestavailable network.

Types of SIM cards:

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1. Full-size SIM: The full-size SIM (or 1FF, 1st form factor) was the first form factor to appear.It has the size of a credit card (85.60 mm × 53.98 mm × 0.76 mm).

2. Mini-SIM: The mini-SIM (or 2FF) card has the same contact arrangement as the full-size SIMcard and is normally supplied within a full-size card carrier, attached by a number of linking

 pieces. This arrangement (defined in ISO/IEC 7810 as ID-1/000) allows such a card to be used in

a device requiring a full-size card, or in a device requiring a mini-SIM card after breaking the

linking pieces.

3. Micro-SIM: The micro-SIM (or 3FF) card has the same thickness and contact arrangements,

 but the length and width are further reduced. The micro-SIM was developed by the European

Telecommunications Standards Institute (ETSI) along with SCP, 3GPP (UTRAN/GERAN),

3GPP2 (CDMA2000), ARIB, GSM Association (GSMA SCaG and GSMNA), Global Platform, Liberty Alliance, and the Open Mobile Alliance (OMA) for the purpose of fitting into devices

too small for a mini-SIM card.

The micro-SIM was designed for backward compatibility. The major issue for backward

compatibility was the contact area of the chip. Retaining the same contact area allows the micro-

SIM to be compatible with the prior, larger SIM readers through the use of plastic cutout

surrounds. The SIM was also designed to run at the same speed (5 MHz) as the prior version.

The same size and positions of pins resulted in numerous "How-to" tutorials and YouTube video

with detailed instructions how to cut a mini-SIM card to micro-SIM size with a sharp knife or

scissors.

International Mobile Station Equipment Identity

The International Mobile Station Equipment Identity or IMEI is a number, usually unique toidentify 3GPP (i.e., GSM, UMTS and LTE) and iDEN mobile phones, as well as some satellite phones. It is usually found printed inside the battery compartment of the phone, but can also bedisplayed on-screen on most phones by entering *#06# on the dial pad, or alongside other systeminformation in the settings menu on smart phone operating systems.

The IMEI number is used by a GSM network to identify valid devices and therefore can be usedfor stopping a stolen phone from accessing that network. For example, if a mobile phone isstolen, the owner can call his or her network provider and instruct them to "blacklist" the phoneusing its IMEI number. This renders the phone useless on that network and sometimes othernetworks too, whether or not the phone's SIM is changed.

The IMEI is only used for identifying the device and has no permanent or semi-permanentrelation to the subscriber. Instead, the subscriber is identified by transmission of an IMSI

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number, which is stored on a SIM card that can (in theory) be transferred to any handset.However, many network and security features are enabled by knowing the current device beingused by a subscriber.

Blacklisting of Stolen Devices

Many countries have acknowledged the use of the IMEI in reducing the effect of mobile phonetheft. For example, in the United Kingdom, under the Mobile Telephones (Re-programming)Act, changing the IMEI of a phone, or possessing equipment that can change it, is considered anoffence under some circumstance.

When mobile equipment is stolen or lost the owner can contact their local operator with a requestthat it should be blocked from the operator's network, and the operator can be expected to do soif required by law in the operator's jurisdiction. If the local operator possesses an Equipment

Identity Register (EIR), it then may put the device IMEI into it, and can optionally communicatethis to shared registries, such as the Central Equipment Identity Register (CEIR) which blackliststhe device in switches of other operators that use the CEIR. With this blacklisting in place thedevice becomes unusable on any operator that uses the CEIR, making theft of mobile equipmenta useless business proposition, unless for parts.

The IMEI number is not supposed to be easy to change, making the CEIR blacklisting effective.However this is not always the case: a phone's IMEI may be easy to change with special tools. Inaddition, IMEI is an un-authenticated mobile identifier (as opposed to IMSI, which is routinely being authenticated by home and serving mobile networks.) Spoofed IMEI can thwart all effortsto track handsets, or target handsets for Lawful Intercept. Australia was first to implement IMEI

 blocking across all GSM networks, in 2003.

GSM V/S CDMA

GSM (Global System for Mobile Communications, originally Groupe Spécial Mobile), is astandard developed by the European Telecommunications Standards Institute (ETSI) to describe protocols for second generation (2G) digital cellular networks used by mobile phones. It is the defacto global standard for mobile communications with over 90% market share, and is available inover 219 countries and territories.

The GSM standard was developed as a replacement for first generation (1G) analog cellular

networks, and originally described a digital, circuit-switched network optimized for  full duplexvoice telephony. This was expanded over time to include data communications, first by circuit-switched transport, then packet data transport via GPRS (General Packet Radio Services) andEDGE (Enhanced Data rates for GSM Evolution or EGPRS).

Subsequently, the 3GPP developed third generation (3G) UMTS standards followed by fourthgeneration (4G) LTE Advanced standards, which are not part of the ETSI GSM standard.

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"GSM" is a trademark owned by the GSM Association. It may also refer to the initially mostcommon voice codec used, Full Rate.

GSM is a cellular network, which means that cell phones connect to it by searching for cells inthe 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 theimplementation environment. Macro cells can be regarded as cells where the base station antennais installed on a mast or a building above average rooftop level. Micro cells are cells whoseantenna height is under average rooftop level; they are typically used in urban areas. Pico cellsare small cells whose coverage diameter is a few dozen meters; they are mainly used indoors.Femtocells are cells designed for use in residential or small business environments and connectto the service provider’s network via a broadband internet connection. Umbrella cells are used tocover 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 propagationconditions from a couple of hundred meters to several tens of kilometers. The longest distance

the GSM specification supports in practical use is 35 kilometers (22 mi). There are also severalimplementations of the concept of an extended cell, where the cell radius could be double oreven 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 pico cell 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 antennasystem. These are typically deployed when significant call capacity is needed indoors, like inshopping 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.

CDMA

Code division multiple access (CDMA) is a channel access method used by various radiocommunication technologies.

CDMA is an example of multiple accesses, which is where several transmitters can sendinformation simultaneously over a single communication channel. This allows several users toshare a band of frequencies. To permit this to be achieved without undue interference betweenthe users, CDMA employs spread-spectrum technology and a special coding scheme (where eachtransmitter is assigned a code).

CDMA is used as the access method in many mobile phone standards such as cdmaOne,CDMA2000 (the 3G evolution of cdmaOne), and WCDMA (the 3G standard used by GSMcarriers), which are often referred to as simply CDMA.

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