NETWORKING-2-PRELIM-LESSON-I-1 NETWORKING.pptx

Networking 2

1. IT 219 NETWORKING 2

2. LESSON I: WIRELESS NETWORKS TECHNOLOGY Introduction to Wireless Communication What is wireless computer networking Advantages and Disadvantages of Wireless Communication Applications of Wireless Communication What is Electromagnetic Waves What is Radio and Microwave Transmission How Infrared Transmission happen What is Radio Interference What are Antenna Styles

3. Introduction to Wireless Communication The birth of wireless communications dates from the late 1800s, when Guglielmo Marconi did the pioneer work establishing the first successful radio link between a land-based station and a tugboat. Since then, wireless communication systems have been developing and evolving with a furious pace. The number of mobile subscribers has been growing tremendously in the past decades. The number of mobile subscribers throughout the world increased from just a few thousand in the early 20th century to close to 1.5 billion in 2004.

4. Introduction to Wireless Communication The early wireless systems consisted of a base station with a high-power transmitter and served a large geographic area. Each base station could serve only a small number of users and was costly as well. The systems were isolated from each other and only a few of them communicated with the public switched telephone networks. Today, the cellular systems consist of a cluster of base stations with low-power radio transmitters. Each base station serves a small cell within a large geographic area. The total number of users served is increased because of channel reuse and also larger frequency bandwidth. The cellular systems connect with each other via mobile switching and directly access the public switched telephone networks.

5. Introduction to Wireless Communication In the early stages, wireless communication systems were dominated by military usage and supported according to military needs and requirements. During the last half a century, with increasing civil applications of mobile services, commercial wireless communication systems have been taking the lead.

6. WIRELESS NETWORKS TECHNOLOGY Wireless computer networking Wireless networks are computer networks that are not connected by cables of any kind. The use of a wireless network enables enterprises to avoid the costly process of introducing cables into buildings or as a connection between different equipment locations. The basis of wireless systems are radio waves, an implementation that takes place at the physical level of network structure. Wireless networks use radio waves to connect devices such as laptops to the Internet, the business network and applications.

7. WIRELESS NETWORKS TECHNOLOGY Types of Wireless Communication Satellite Communication Infrared Communication Broadcast Radio Microwave Communication Wi-Fi Mobile Communication Systems Bluetooth Technology

8. WIRELESS NETWORKS TECHNOLOGY Advantages and disadvantages of Wireless Communication Advantages : Freedom from wires Easy to setup Better or global coverage Flexibility Cost-effectiveness Mobile and portable

9. WIRELESS NETWORKS TECHNOLOGY Advantages and disadvantages of Wireless Communication Disadvantages : As communication is done through open space, it is less secure. Unreliability More open to interference. Increased chance of jamming. Transmission speed is comparably less.

10. WIRELESS NETWORKS TECHNOLOGY Applications of Wireless Communication : Satellite system Television remote control Wi-Fi Paging system Wi-Max Security systems

11. WIRELESS NETWORKS TECHNOLOGY Applications of Wireless Communication : Cellphones Computer interface devices Bluetooth Global Positioning System (GPS) Global System for Mobile Communications (GSM)

12. WIRELESS NETWORKS TECHNOLOGY Electromagnetic Waves Electromagnetic waves are formed when an electric field (which is shown in figure) couples with a magnetic field. Magnetic and electric fields of an electromagnetic wave are perpendicular to each other and to the direction of the wave.

13. WIRELESS NETWORKS TECHNOLOGY Radio and Microwave Transmission A radio wave is most efficiently radiated from a metal antenna whose length is a suitable fraction of a wavelength, such as half wave, and reception of radio waves is the best when the receiving antenna is also a suitable fraction of a wavelength.  The wave is intercepted by the antenna, which converts the wave into an electrical signal that is transmitted to a radio or television set. Within the radio or television set, the electrical signal is converted to a sound wave that can be broadcast through speakers.

14. WIRELESS NETWORKS TECHNOLOGY Radio and Microwave Transmission Some of the areas of applications of radio waves are − Broadcasting and multicasting Fixed and mobile radio communications AM and FM radio Television Marine communication Wireless computer networks Cordless phones

15. WIRELESS NETWORKS TECHNOLOGY Radio and Microwave Transmission Microwave is a line-of-sight wireless communication technology that uses high frequency beams of radio waves to provide high speed wireless connections that can send and receive voice, video, and data information. Microwave radio transmission is commonly used in point-to-point communication systems on the surface of the Earth, in satellite communications, and in deep space radio communications. Other parts of the microwave radio band are used for radars, radio navigation systems, sensor systems, and radio astronomy.

16. WIRELESS NETWORKS TECHNOLOGY Radio and Microwave Transmission Applications Long distance telephone communication Cellular phones Television networks Satellites Wireless LANs

17. WIRELESS NETWORKS TECHNOLOGY Infrared Transmission Infrared waves are those between the frequencies 300GHz and 400THz in the electromagnetic spectrum. Their wavelengths are shorter than microwaves but longer than visible light. They cannot penetrate walls and sun’s infrared rays interfere with these rays. It cannot be used for long – range communication. As their usage is confined within closed space, they do not need any government permissions for their applications.

18. WIRELESS NETWORKS TECHNOLOGY Infrared Transmission Applications of Infrared Waves in Communications Remote controls for television, stereos and other home appliances. Wireless LANs Wireless modem, keyboard, mouse, printer etc.. Fire detectors Night vision systems Intrusion detection systems Motion detectors

19. WIRELESS NETWORKS TECHNOLOGY Radio Interference Radio Interference is the term used to describe a range of different situations in which transmissions other than those from authorised users of an Radio Telephone F requency (RTF) interfere with radio reception. Radio Interference occurs when unwanted radio frequency signals disrupt the use of your television, radio or cordless telephone. Interference may prevent reception altogether, may cause only a temporary loss of a signal, or may affect the quality of the sound or picture produced by your equipment.

20. WIRELESS NETWORKS TECHNOLOGY Causes of radio interference The signal may be reduced by an obstruction blocking your antenna from the signal, such as trees, hills, or severe weather. Multi-path signals causing cancellation of the primary signal. You're too far away from the transmitter. Your receiver is faulty, or your antenna system is a low-gain type or faulty. AM radio reception of weak and/or distant stations at night is prone to fading and distortion, caused by the simultaneous reception of both wanted and unwanted signals.