1 overview mobile comm handset sim r

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Mobile Communications Overview of Mobile Communication : Handset & SIM

BSNL Online Awareness Programme Page 1 of8

For Restricted Circulation

1 OVERVIEW OF MOBILE COMMUNICATION-HANDSET, SIM

STRUCTURE

1.1 INTRODUCTION1.2 LEARNING OBJECTIVES1.3 WIRELESS COMMUNICATIONS: INCEPTION AND OVERVIEW1.4 MOBILE HANDSET1.5 SIM (SUBSCRIBER IDENTITY MODULE)1.6 IDENTIFIERS1.7 SUMMARY1.8 SELF ASSESSMENT QUESTIONS1.9 REFERENCES AND SUGGESTED FURTHER READINGS

1.1 INTRODUCTIONWe see that today that Mobile telephones has become an essential part of daily life. In the

last one decade, our country has witnessed tremendous growth in mobile communication

area. Currently number of mobile telephone connections are many a times more than that

of fixed (wire line) telephone connections. About 7- 8 million mobile subscribers are

added every month in our country.

In mobile communications the connectivity of the user (Mobile Subscriber) with Mobile

Network is through radio signals and there are no wires from the network to user

equipment. The objective of mobile communications is to provide a truly Anytime,

Anywhere communication. Today mobile is providing Voice, messaging and a number of

data services to users like real time TV, on line payments of utility bills, m-commerce,news, entertainments etc.

Although mobile telephony can be seen in broad sense as the wireless communication and

wireless services can be offered through various technologies like GSM, CDMA, Cor-

DECT, etc. but here we will talk about GSM (Global System for Mobile

Communication) as a wireless communication technology.

1.2 LEARNING OBJECTIVESAfter completion of this training module, trainees will:

Be able to appreciate difference in Fixed line and Mobile networks.


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Have a broad understanding of Mobile Communications. Be able to understand concept of a Cell and Radio Coverage. Be able to understand key functions of Handset and SIM card in GSM Network.

1.3 WIRELESS COMMUNICATIONS: INCEPTION ANDOVERVIEW

From ancient to modern times, mankind has been looking for means of long distance

communications. For centuries, letter proved to be the most reliable way to transmit

information. Fire, flags, horns, etc. were used to transmit information faster. Technical

improvements in the 19th century simplified long distance communications resulting in

Telegraphy, and later on telephony. Both techniques were wire line. In 1873, J.C.Maxwell

laid the foundation of the electro-magnetic theory, which is still valid today. It would

however several decades after (in 1895) that Marconi made economic use of this theory

by developing devices for wireless transmission of Morse signals (in 1895). Voice wastransmitted on wireless for the first time in 1906 (R. Fesseden), and one of the first radio

broadcast transmission 1909 in New York.

The economically most successful wireless application in the first half of the 20th

century was radio broadcast. There is one transmitter, the so-called radio station.

Information, such as news, music, etc. is transmitted from the radio station to the receiver

equipment, the radio device. This type of one-way transmission is called simplex

transmission. The transmission takes place only in one direction, from the transmitter to

the receiver. This was the first type of fixed wireless transmission.

For conversation, a technical solution is required, where the information flow can takeplace in two directions. This type of transmission is called duplex transmission. Walky-

talky was already available the early 1930's. This system already allowed a transmission

of user data in two directions, but there was a limitation: The users were not allowed to

transmit at the same time. In words, you could only receive or transmit user information

at any given instant of time. This type of transmission was therefore often called semi-

duplex transmission. For telephony services, a technical solutions is required, where

subscribers have the impression, that they can speak (transmit) and hear (receive)

simultaneously. This type of transmission solution is regarded as full duplex transmission.


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Comparison of Wire Line &

Wireless Telephony

Feature WireLine WireLess

UserTerminal

TelephoneSet

MobileHandset

Portability Fixed Portable

Connectivity Wired Wireless

Services

offered

Limited Many

Figure 1: Comparison of Wire-line and wireless systems.

A limited amount of mobility along with duplex transmission resulted in the Mobile

Telephony. The first commercial wireless car phone telephone service started in the late1940 in St. Louise, Missouri (USA). It was a car phone service, because at this time, the

mobile phone equipment was bulky and heavy. Actually, in the start-up, it occupied the

whole back of the car. But it was a real full duplex transmission solution. In the 1950s,

several vehicle radio systems were installed in Europe also. These systems are called

single cell systems. The user data transmission takes place between the mobile phone and

the base station (BS). A base station transmits and receives user data. While a mobile

phone is only responsible for its users data transmission and reception, a base station is

capable to handle the calls of several subscribers simultaneously. The transmission of

user data from the base station to the mobile phone is called downlink (DL), the

transmission from the mobile phone to the base station uplink (UL) direction. The area,

where the wireless transmission between mobile phones and the base station can take

place, is the base stations supply area, called cell.

Figure 2: Cell Coverage Area.

Cell = supply area

Uplink

(UL)

Base station

Downlink (DL)


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Single cell systems are quite limited. The more and more distant the subscriber is from

the base station, the lower the quality of the radio link. If the subscriber is leaving the

supply area of the cell, the communication is not possible any more. In other words, the

mobile communication service was only available within the cell. In order to overcome

this limitation, Multi-cellular systems were introduced. A cellular mobile communication

system consists of several cells, which can overlap. By doing so, a whole geographicalarea can be supported with the mobile communication service.

But what happens, when a subscriber moves during a call from one cell to another

cell? It would be very annoying, if the call is dropped. If the subscriber is leaving a cell,

and in parallel is entering a new cell, then the system makes new radio resource available

in the neighboring cell, and then the call is handed over from on cell to the next one. By

doing so, service continuation is guaranteed, even when the subscriber is moving. This

process is called handover (HO).

A handover takes place during a call, i.e. when the mobile phone is in active

(dedicated) mode. A mobile phone can also be in idle mode. In this case, the mobilephone is switched on, but no resources are allocated to it to allow transmission of user

data. In this mode, the mobile phone is still listening to information, broadcasted by the

base station. Why? Imagine, there is an incoming call to this mobile. The mobile phone is

then paged in the cell. This means the phone receives information that there is a mobile

terminated call. A cellular system may consist of hundreds of cells. If the mobile network

does not know, in which cell the mobile phone is located, it must be paged in all of them.

To reduce load on networks, paging is done in small parts rather to a group of cells of a

mobile network. The group of cells in administrative units in operation is called location

area (LA). A mobile phone is paged in only one location area at a time. The LA is used

by the GSM system to search for a subscriber in an active state.

But how does the cellular system know, in which location area the mobile phone is

located? And how does the mobile phone know? In every cell, system information is

continuously transmitted. The system information includes the location area information.

In the idle mode, the mobile phone is listening to this system information. If the user

moves from one cell to the next cell, and the new cell belongs to the same location area,

the mobile stays idle. If the new cell belongs to a new location area, then the mobile

phone has to become active. It starts a communication with the network; information is

send to the mobile network. This is stored in databases within the mobile network, and if

there is a mobile terminated call, the network knows where to page the subscriber.

The process, where the mobile phone informs the network about its new location iscalled Location Update Procedure (LUP). The registration of the Mobile is done at the

VLR (Visitor Location Register) associated with the Mobile Switching Network.

1.4 MOBILE HANDSETAs mentioned earlier also, the mobile handset is the only mobile part in the mobile

communication system. A mobile phone (also known as a cellular phone or cell phone) is

a device that can make and receive telephone calls over a radio link whilst moving around

a wide geographic area.


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The first mobile telephone call was

made on 17 June 1946 from a car

in St. Louis, Missouri, USA, using

the Bell System's Mobile

Telephone Service.[10] This was

followed in 1956 by the worlds

first partly automatic car phone

system, Mobile System A (MTA)

in Sweden. The MTA phones werecomposed of vacuum tubes and

relays, and had a weight of 88.2

pounds (40 kg)

In addition to telephony, modern mobile phones also support a wide variety of other

services such as text messaging, MMS, email, Internet access, short-range wireless

communications (infrared, Bluetooth), business applications, gaming and photography.

Mobile phones that offer these and more general computing capabilities are referred to as

Smartphone.

Figure 3: The beginning of Mobile phones.

The common components found on all phones are:

An input mechanism to allow the user to interact with the phone. Most commoninput mechanism is a keypad, but touch screens are also found in some high-end

Smart phones.

Antenna to transmit and receive RF signals. Display: Today, we have displays of different sizes and Compositions

Associated Terms: AMOLED, LCD, Super LCD, Retina, PPI, Clear Black.

Processor: The processor is the engine that drives phone. As phones becomemore powerful, processors are getting into dual core and quad core territory.

Associated Terms: Dual Core, Quad Core, 800 MHz,

1/1.2/1.5GHz, Snapdragon, Tegra, Intel, Qualcomm.

RAM: The RAM allows the phone to run multiple applications simultaneouslyand do various tasks in the background.

Associated Terms: 256 MB, 512 MB, 768 MB, 1 GB.

Camera: Once considered a luxury in Smartphones, theCamera is now an integral part of Smartphones.


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Associated terms: 3.2/5/8/12/41 Megapixels, Auto Focus, Shooting Modes, HD

video, LED/Xenon flash.

Battery: The battery (with a capacity expressed in mAh or milli ampere hour)determines how long your phone keeps working on a single charge.

Associated terms: Li-ion, mAh, removable, non-removable.

Device Connectivity: There are various wired and wireless technologiesembedded today on mobile devices to connect them with other phones, tablets,

televisions or various accessories.

Associated terms: USB On-The-Go, HDMI, Bluetooth 2.0/2.1/3.0, Wi-Fi.

Mobile Internet Connectivity: Phones are no longer used to just make calls andswap texts. Almost every Smartphone now comes with some sort of Internet

connectivity via the operator's data services.

Associated terms: HSPA, HSDPA, 3G, 3.5G, 4G, GPRS/EDGE.

OS/Platform: The operating system of a phone is the software that makes thephone work, handling basic tasks like calling, texting as well as more complex

ones like mail and Web browsing. It works in a similar way like Windows and

Mac OS do, on a computer.


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Figure 4: Components of a Mobile Phone.

1.5 SIM (SUBSCRIBER IDENTITY MODULE)A SIM is an integrated circuit that securely stores the Information related to

the subscribers identity which is used to identify and authenticate the

subscriber within the GSM Networks.

A SIM is embedded into a removable SIM card, which can be transferred

between different mobile devices. 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: a personal identification number (PIN) for ordinary use and a

personal unblocking code (PUK) for PIN unlocking.

What is inside the SIM?

Hardware: CPU, I/O Devices, ROM, RAM, EEPROM

Software: IMSI, PIN, PUK, Authentication Keys e.g. Ki, Kc, Algorithms like A3,

A8.

A SIM can be used for various basic applications like storing contact book, SMS etc. as

well as for Value Added Services (VAS) like STK. A SIM may be with single IMSI orwith two IMSI (Dual IMSI) or three IMSI (triple IMSI). Dual IMSI or Triple IMSI

application allows the operator to offer more than one different accounts on the same SIM

card without any impact on the network side.

1.6 IDENTIFIERSThe Handset and SIM are identified in the network with a set of identifiers. The

Handset is identified with IMEI (International Mobile Equipment Identity). Whereas SIM

is identified with ICCID (Integrated Circuit Card Identifier) and IMSI (International

Mobile Subscriber Identity).

1.7 SUMMARYGlobal System for Mobile communications (GSM) is the most widely used wireless

technology in the world today. GSM is a second generation (2G) wireless technology thatprovides high-quality voice and circuit-switched data services in a wide variety of

spectrum bands. GSM pioneered many of the world's most popular data services, such as

Short Message Service (SMS) and Multimedia Message Service (MMS).

The GSM subscriber is provided with a SIM which is used to identify and authenticate

the subscriber over the networks. The SIM provides the freedom to use a compatible


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handset of his/ her choice. Handsets are available ranging from a very basic phone to

smart phones.

1.8 SELF ASSESSMENT QUESTIONS1. Name the only mobile component in mobile communication2. Name the various identifiers used with SIM and Handsets.3. State various advantages of mobile communication over wire line communication.

1.9 REFERENCES AND SUGGESTED FURTHER READINGS1. GSM System Engineering by Asha Mehrotra2. The GSM System for Mobile Communications by Michel Mouly, Marie-

Bernadette Pautet.

3. Wireless Communications: Principles and Practice By Theodore S. Rappaport.

1 overview mobile comm handset sim r

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