Telecommunication Networks

Index

Communication

Wireless Communication

·         Cellular & Non-Cellular Wireless Communication

Types of Wireless Communication

·         Fixed Wireless

·         Mobile Wireless

·         Portable Wireless           

·         IR Wireless

·         Wireless WAN

·         Wireless LAN

Wireless Devices

Wireless Technology

·         Global System for Mobile Communication (GSM)

·         General Packet Radio Service (GPRS)

·         Enhanced Data GSM Environment (EDGE)

·         Universal Mobile Telecommunications System (UMTS)

·         Blue Tooth Technology from INTEL

Wireless Application Protocol (WAP)

·         Wireless Application Environment (WAE)

·         Wireless Session Layer (WSL)

·         Wireless Transport Layer Security (WTLS)

·         Wireless Transport Layer (WTP)

Radar

·         Types of Radar

Security

Conclusion

  

COMMUNICATION:

A link or transfer of information b/w any two objects is called communication.

Wireless Communication:

Wireless is a term used to describe telecommunications in which electromagnetic waves (rather than some form of wire) carry the signal over part or all of the communication path. Some monitoring devices, such as intrusion alarms, employ acoustic waves at frequencies above the range of human hearing; these are also sometimes classified as wireless.

The first wireless transmitters went on the air in the early 20th century using radiotelegraphy (Morse code). Later, as modulation made it possible to transmit voices and music via wireless, the medium came to be called "radio." With the advent of television, fax, data communication, and the effective use of a larger portion of the spectrum, the term "wireless" has been resurrected.

CELLULAR AND NON-CELLULAR WIRELESS COMMUNICATION:

Wireless communication systems can be roughly divided into two categories: cellular   and non-cellular systems. In cellular systems the area to be covered is divided in a number of cells. All communication in a cell goes via a single base-station located in that cell. Hand-over     protocols and connections between base-stations enable roaming over cell borders. The consequence of this concept is that both an infrastructure and a complex protocol are required.       Non-cellular systems form another category of wireless communication systems for which no infrastructure is required. In this sense the complete system itself is mobile.

 
 

This thesis deals with systems providing short distance, multi-access, ad-hoc based, point-to-point communication links. Shortly, we focus on ``non-cellular wireless communication systems''. Applications can primarily be found as indoor data communication systems as illustrated. This figure only shows a number of properties of the target communication system.

The main properties are listed below:

·         Non-Cellular: Systems do not require an infrastructure. Our target system is a non-cellular communication system for short distances.

·         Multi-Access: Enables several simultaneous communication links. In the figure two such links are shown.

·         Random-Access: This term is in this context defined as the ability of users to initiate a communication link at any arbitrary moment.

·         Digital Data-Communication Links: Although not completely clear from the picture, the target system is a digital communication system. Applications can be both data-links and (via a speech-coder) speech-links.

TYPES OF WIRELESS COMMUNICATION:

·         Fixed Wireless -- The operation of wireless devices or systems in homes and offices, and in particular, equipment connected to the Internet via specialized modems.

·         Mobile Wireless -- The use of wireless devices or systems aboard motorized, moving     vehicles; examples include the automotive cell phone and PCS (personal communications services).

·         Portable Wireless -- The operation of autonomous, battery-powered wireless devices or systems outside the office, home, or vehicle; examples include handheld cell phones and PCS units.

·         IR Wireless -- The use of devices that convey data via IR (infrared) radiation; employed in certain limited-range communications and control systems.

·         Wide Area Network (WAN) -- Building blocks include microprocessors, flash memory, base band chipsets, software and reference designs.

·         Wireless Local Area Network (WLAN) -- Products provide private, trusted, high-speed connectivity, mobile roaming and building-wide coverage for small, medium and enterprise organizations.

WIRELESS DEVICES:

Common examples of wireless equipment in use today include:

·        Cellular Phones And Pagers -- Provide connectivity for portable and mobile applications, both personal and business.

·        Global Positioning System (GPS) -- Allows drivers of cars and trucks, captains of boats and ships, and pilots of aircraft to ascertain their location anywhere on earth.

·   Cordless Computer Peripherals -- The cordless mouse is a common example; keyboards and printers can also be linked to a computer via wireless.

·         ·        Cordless Telephone Sets -- These are limited-range devices, not to be confused with cell phones.

·        Home-Entertainment System Control Boxes -- The VCR control and the TV channel control are the most common examples; some hi-fi sound systems and FM broadcast receivers also use this technology.

·        Remote Garage-Door Openers -- One of the oldest wireless devices in common use by consumers; usually operates at radio frequencies.

·        Two-Way Radios -- This includes Amateur and Citizens Radio Service, as well as business, marine, and military communications.

·        Baby monitors -- These devices are simplified radio transmitter/receiver units with limited range.

Wireless Technology

Wireless technology is rapidly evolving, and is playing an increasing role in the lives of people throughout the world. In addition, ever-larger numbers of people are relying on the technology directly or indirectly. (It has been suggested that wireless is overused in some situations, creating a social nuisance).

More specialized and exotic examples of wireless communications and control include:

·         Global System for Mobile Communication (GSM) -- A digital mobile telephone system used in Europe and other parts of the world; the de facto wireless telephone standard in Europe.

·          General Packet Radio Service (GPRS) -- A packet-based wireless communication service that provides continuous connection to the Internet for mobile phone and computer users.

·          Enhanced Data GSM Environment (EDGE) -- A faster version of the Global System for Mobile (GSM) wireless service.

·         Universal Mobile Telecommunications System (UMTS) -- A broadband, packet-based system offering a consistent set of services to mobile computer and phone users no matter where they are located in the world.

·         Blue tooth* Wireless Technology -- Allows mobile PCs, cellular phones and other devices to communicate together, offering personal connectivity freedom for home and business mobility.  

Wireless Application Protocol (WAP):

WAP (Wireless Application Protocol) is a specification for a set of communication protocols to standardize the way that wireless devices, such as cellular telephones and radio transceivers, can be used for Internet access, including e-mail, the World Wide Web, newsgroups, and Internet Relay Chat (IRC). While Internet access has been possible in the past, different manufacturers have used different technologies. In the future, devices and service systems that use WAP will be able to interoperate.

The WAP layers are:

·         Wireless Application Environment (WAE)

·         Wireless Session Layer (WSL)

·         Wireless Transport Layer Security (WTLS)

·         Wireless Transport Layer (WTP)

Four companies conceived the WAP: Ericsson, Motorola, Nokia, and Unwired Planet (now Phone.com). The Wireless Markup Language (WML) is used to create pages that can be delivered using WAP.

Security

Security of Wireless Transmissions:

Currently, few wireless communication protocols offer encryption of the transmission. In security models of protocols that do have security encryption (such as WAP), there have been identified transmission security weaknesses in current protocols.

RADAR

Radar, which is an acronym for radio detection and ranging, refers to a portion of the electromagnetic spectrum with wavelengths extending from 1 mm. to 1 m. The term microwave, although sometimes used interchangeably with the term radar, is therefore a misnomer since these waves are about 2.5 million times longer than the shortest visible light waves!

Advantages of utilizing these wavelengths include their ability to penetrate haze, light rain, clouds and other atmospheric particulates. Radar views of Earth may be obtained at any time of day (even at night), under most any condition. The images are often very different from those taken in other wavelengths, and hence reveal supplementary information about terrain surfaces. Since microwaves are much longer than visible light waves, radar images often appear "smoother" than visible spectrum images.

Active & Passive:

Radar sensors may be divided into two groups: passive and active. Passive systems simply record microwave-region wavelengths of energy emitted from the Earth's surface. Microwave radiometers are passive systems. The signal they receive is an amalgam of thermal emissions from the ground and the atmosphere, plus scattered emissions originating in the atmosphere and extra terrestrially. Active systems record the reflected signals of microwaves they transmit. This Internet site will concentrate on active radar systems.

Types Of Active Radar:

There are three types of active radar remote sensors. They include:

·         Doppler radar: Commonly used to detect motion (motor vehicle/traffic applications).

·         Plan Position Indicators (PPI): Used by air traffic controllers and weather forecasters.

·         Side-looking airborne radar (SLAR): Originally developed for military reconnaissance in the early 1950s for all-weather, day/night imaging.

Conclusion

The greatest marvel of science which was bestowed on human kind to connect them with one an other, an invisible wire having only one inlet and more then one outlets which has stretched over the world so all the human races can feel and love each other by interacting, listening, learning and sharing each other's ideas like a big family. On the other side this communication has completely changed the scenarios of modern warfare, a warfare with out wires, with out the delay of receiving and sending messages to friendly forces where every bit of information of battle field reaches the command headquarters within microseconds, where super weapons can search and destroy there targets with pin-point accuracy, where any movement of your enemy is not a surprise for you.

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