IT's All About

Wireless and Mobile Computing

Posted: November 22nd 2012

Okaay.. this is our next discussion,
it is all about Wireless and Mobile Computing…

What is Wireless and what is Mobile? Basically, it is difference. But today, technology makes it become one each other. When you see a mobile device, it could do Wireless thing and do a Mobile Computing. Let me tell you about the definition.
Wireless is come from Wire and less, it means no need of wired things to do.
Wireless device : is a device who have an ability to communicated without wire.

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Wireless Technology

The Example of device which have a wireless technology is : PDA, Cell Phone, Smartphone, Wireless Mouse / Keyboard, Laptop, Pager, and many other. On the wireless technology there is a protocol which is a rule that makes the communication run smoothly, it is called Wireless Application Protocol. It is the standard that enables wireless devices with tiny display screens, low bandwidth connection and minimal memory to access web-based information and services.

Another wireless technology is Opera mini browser, this is a type of Microbrowsers which have a function as an internet browser with small file size that can work within low memory of wireless device and the low bandwidth of wireless network. Opera mini, could compress the web to be become lighter and use low bandwidth. The Opera mini, use the picture to compress the bandwidth.

Wireless Transmission Media

  • Radio Waves
  • Microwaves
  • Infrared

The difference between Radio waves and microwaves

There is no clear difference between radio waves and microwaves. Electromagnetic waves ranging in frequencies between 3KHz and 1 GHz are normally called radio waves. Waves ranging in frequencies between 1 and 300 GHz are normally called microwaves.

Radio Waves Signal

Radio waves are normally omnidirectional. When an antenna transmits radio waves, they are propagated in all directions. This means that the sending are receiving atennas do not have to be aligned.

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The omnidirectional characteristics of radio waves make them useful for multicasting, in which there is one sender but many receivers. Our AM and FM radio stations, cordless phones and television are examples of multicasting

The Disadvantage of Radio Waves

Radio waves transmitted by one antenna are susceptible to interference by another antenna that is sending signals of the same frequency or band.

Microwaves

Electronic waves with frequencies between 1GHz to 300GHz are normally called microwaves. Unlike radio waves, microwaves are uniderctional, in which the sending and receiving antennas need to be aligned.

Microwaves propagation is line-of-sight therefore towers with mounted antennas need to be in direct sight of each other. Due to the unidirectional property of microwaves, a pair of antennas can be placed aligned together without interfering with another pair of antennas using the same frequency.

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 The disadvantage of the microwaves

High-frequency microwaves cannot penetrate walls. This is why receiving antennas cannot be placed inside buildings.

Infrared

Infrared is used in devices such as the mouse, wireless keyboard and printers. Some manufacturers provide a special port called the IrDA port that allows a wireless keyboard to communicate with a PC.

Infrared signals have frequencies between 300GHz to 400THz. They are used for short-range communciation.

Infrared signals have high frequencies and cannot penetrate walls. Due to its short-range communication system, the use of an infrared communication system in one room will not be affected by the use of another system in the next room.

This is why using an infrared TV remote home will not interfere with the use of infrared TB remote control.

The disadvantage of using infrared

Infrared signal cannot be used for long distance communication. In addition, we cannot use infrared waves outside a building because sun’s ray contain infrared waves that can interfere waves that can interfere with communication.

Satellite 

The use of satellite to communicate, the wider area makes satellite is suitable for large area communication. Such as GPS, Internet, Television, and other communication needs.
there are three types of the orbit :

  1. GEO (Geostationary Earth Orbit) :  orbits 22,300 miles directly above the equator and maintains a fixed position; excellent for TV signals.
  2. MEO (Medium Earth Orbit) :  are located 6,000 miles above the earth’s surface and move; used for GPS and are less expensive.
  3. LEO (Low Earth Orbit) :  are 400 to 700 miles above the surface and move much quicker so they require many to have adequate coverage; use for telephone
One information : there are should be three satellite to give a coordinate for GPS, because it’s like an x,y,z coordinate on 3D model.
Wireless Computer Network and Internet Access
IEEE standards for wireless computer networks include:
IEEE 802.15 (Bluetooth) for wireless personal area networks  (PANs) and 802.15.4 (Zigbee).
IEEE 802.11 (Wi-Fi) for wireless local area networks (WLANs)
IEEE 802.16 (Wi-Max) for wireless metropolitan area networks (WMANs)
IEEE 802.20 (proposed) for wireless wide area networks (WWANs).
Those are have a difference ability and use. The common is Bluetooth on a mobile device like cell phone, smart phone, and laptop. Wifi is also a common and integrated in Laptop and many other mobile device like cell phone and smartphone. But for the WiMax, it is still new things, but a big country has used it, not like Indonesia, which it still on development.
Mobile Computing
Mobile Computing is, doing a computation with move from a place to another place. This is the trend today and for the future which there will be no more desktop computer or maybe all device will be no need a cable so it can be moving.

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