Mobile communcation

We understand by mobile communication as the use of technology that allows us to communicate with others in different locations without the use of cables. Mobile communication makes our life easier, saves time and effort.

Security:

                                                             Mobile device security, has become increasingly important in mobile computing of particular concern is the security of personal and business information now stored on smartphones.

Types of Wireless Communication

The different types of wireless communication mainly include, IR wireless communication, satellite communication, broadcast radio, Microwave radio, Bluetooth, Zigbee etc.

Satellite Communication

Satellite communication is one type of self contained wireless communication technology, it is widely spread all over the world to allow users to stay connected almost anywhere on the earth. When the signal (a beam of modulated microwave) is sent near the satellite then, satellite amplifies the signal and sent it back to the antenna  receiver which is located on the surface of the earth. Satellite communication contains two main components like the space segment and the ground segment.The ground segment consists of  fixed or mobile transmission, reception and ancillary equipment and the space segment, which mainly is the  satellite itself.

Infrared Communication

Infrared wireless communication communicates information in a device or systems through IR radiation . IR is electromagnetic energy at a wavelength that is longer than that of red light. It is used for security control, TV remote control and short range communications. In the electromagnetic spectrum, IR radiation lies between microwaves and visible light. So, they can be used as a source of communication

Broadcast Radio

The first wireless communication technology is the open radio communication to seek out widespread use, and it still serves a purpose nowadays. Handy multichannel radios permit a user to speak over short distances, whereas citizen’s band and maritime radios offer communication services for sailors. Ham radio enthusiasts share data and function emergency communication aids throughout disasters with their powerful broadcasting gear, and can even communicate digital information over the radio frequency spectrum.

Microwave Communication

Microwave wireless communication is an effective type of communication, mainly this transmission uses radio waves, and the wavelengths of radio waves are measured in centimeters. In this communication, the data or information can be transfers using two methods. One is satellite method and another one is terrestrial method.

Wi-Fi

Wi-Fi is a low power wireless communication, that is used by various electronic devices like smart phones, laptops, etc.In  this setup, a router works  as a communication hub wirelessly. These networks allow users to connect only within close proximity to a router. WiFi is very common in networking applications which affords portability wirelessly. These networks need to be protected with passwords for the purpose of security, otherwise it will access by others

Bluetooth Technology

The main function of the Bluetooth technology is that permits you to connect a various electronic devices wirelessly to a system for the transferring of data.Cell phones are connected to hands free earphones, mouse, wireless keyboard. By using Bluetooth device the information from one device to another device. This technology has various functions and it is used commonly in the wireless communication market.

Advantages of Wireless Communication

·         Any data or information can be transmitted faster and with a high speed

·         Maintenance and installation is less cost for these networks.

·         The internet can be accessed from anywhere wirelessly

·         It is very helpful for workers, doctors working in remote areas as they can  be in touch with medical centers.

Disadvantages of Wireless Communication

·         An unauthorized person can easily capture the wireless signals which  spread through the air.

·         It is very important to secure the wireless network so that the information cannot be misused by unauthorized users

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·         Mobile Phone Communication. How it works?

A mobile phone is an electronic device used for mobile telecommunications over a cellular network of specialized base stations known as cell sites. A cell phone offers full Duplex Communication and transfer the link when the user moves from one cell to another. As the phone user moves from one cell area to another, the system automatically commands the mobile phone and a cell site with a stronger signal, to switch on to a new frequency in order to keep the link.

 History of Mobile Communication

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Wireless communication was a magic to our ancestors but Marconi could initiate it with his wireless telegraph in 1895. Wireless Communication can be classified into three eras.

• Pioneer Era (Till 1920)
• Pre Cellular Era(1920-1979)
• Cellular Era (beyond 1979)

The first commercial mobile telephone system was launched by BELL in St. Louis, USA, in 1946. Few lucky customers got the services. Early mobile systems used single high power transmitters with analog Frequency Modulation techniques to give coverage up to about 50 miles and hence only limited customers could get the service due to this severe constraints of bandwidth.

Cellular Era

To overcome the constraints of bandwidth scarcity and to give coverage to larger sections, BELL lab introduced the principle of Cellular concept. By frequency reuse technique this method delivered better coverage, better utility of available frequency spectrum and reduced transmitter power. But the established calls are to be handed over between base stations while the phones are on move.

Even though the US based BELL lab introduced the cellular principle, the Nordic countries were the first to introduce cellular services for commercial use with the introduction of the Nordic Mobile Telephone (NMT) in 1981.

First Generation Systems

All these systems were analog systems, using FDMA technology. They are also known as First Generation (1G) systems. Different systems came into use based on the cellular principle. They are listed below.

Year	Mobile System
1981	Nordic Mobile Telephone(NMT)450
1982	American Mobile Phone System(AMPS)
1985	Total Access Communication System(TACS)
1986	Nordic Mobile Telephony(NMT)900

Disadvantages of 1G systems

• They were analog and hence are were not robust to interference.
• Different countries followed their own standards, which were incompatible.

To overcome the difficulties of 1G, digital technology was chosen by most of the countries and a new era, called 2G, started.

Advantages of 2G

• Improved Spectral Utilization achieved by using advanced modulation techniques.
• Lower bit rate voice coding enabled more users getting the services simultaneously.
• Reduction of overhead in signaling paved way for capacity enhancement.
• Good source and channel coding techniques make the signal more robust to Interference.
• New services like SMS were included.
• Improved efficiency of access and hand-off control were achieved.

Name of the Systems	Country
DAMPS-Digital Advanced Mobile Phone System	North America
GSM-Global System for Mobile communication	European Countries and International applications
JDC - Japanese Digital Cellular	Japan
CT-2 Cordless Telephone–2	UK
DECT-Digital European Cordless Telephone	European countries

History of GSM

GSM standard is a European standard, which has addressed many problems related to compatibility, especially with the development of digital radio technology.

Milestones of GSM

• 1982 - Confederation of European Post and Telegraph (CEPT) establishes Group Special Mobile.
• 1985 - Adoption of list of recommendation was decided to be generated by the group.
• 1986 - Different field tests were done for radio technique for the common air interface.
• 1987 - TDMA was chosen as the Access Standard. MoU was signed between 12 operators.
• 1988 - Validation of system was done.
• 1989 - Responsibility was taken up by European Telecommunication Standards Institute (ETSI).
• 1990 - First GSM specification was released.
• 1991 - First commercial GSM system was launched.

Frequency Range of GSM

GSM works on four different frequency ranges with FDMA-TDMA and FDD. They are as follows −

System	P-GSM (Primary)	E-GSM (Extended)	GSM 1800	GSM 1900
Freq Uplink	890-915MHz	880-915MHz	1710-1785Mhz	1850-1910MHz
Freq Downlink	935-960MHz	925-960MHz	1805-1880Mhz	1930-1990MHz

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·         Mobile phone is primarily designed for Voice communication. In addition to the standard voice function, new generation mobile phones support many additional services, and accessories, such as SMS for text messaging, email, packet switching for access to the Internet, gaming, Bluetooth, camera with video recorder and MMS for sending and receiving photos and video, MP3 player, radio and GPS.

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 presented by

P.VIJAYALAKSHMI

18JG5A0501

22-12-2018.