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Wireless Communication - Media, Wifi Lifi, Satellite Communication, Mobile Communication

Wi-fi (Wireless Fidelity)

          Advantages

          Limitations

Lifi (light fidelity)

Mobile Communication

                                                                                                                                                                       

 Wireless Communication - Media, Wifi Lifi,           Satellite Communication, Mobile Communication

  Wi-fi (Wireless Fidelity)                                                                      

 wife is an alternative network to wired network which is commonly used for connecting devices in wireless mode. Wifi is stand for Wireless Fidelity is generic term that refers to IEEE 802.11 standard for wireless local networks or WLANs wifi connects computers to each other, to the internet and to the wired network. Wifi uses radio technology to transmit and receive data at high speed. 

 • IEEE 802.11 b - 1999 

 • IEEE 802.11a - 2001 

 • IEEE 802.11g - 2003 

 Advantages 

 • Mobility  

• Ease of installation 

 • Flexibility  

• Cost 

 • Reliability 

 • Security  

• Use unlicensed part of the radi spectrum 

 • Roaming 

 • Speed 

 Limitations 

 • Interference  

• Degradation in performance. 

 • High Power Consumption 

 • Limited range 

 Wifi is technology for radio wireless local area networthing of divices based on the IEEE 802.11 standards. wifi is a trademark of the wifi Alliance, which restricts the use of the term wifi certified to products that successfully complete interoperability certification testing. 

  Lifi (light fidelity)                                                                               

 Lifi is a derivative of optical wireless communication (OWC) technology using light from light emiting diodes (LED) as a medium to deliver networked, mobile, high speed communication in a similar manner to wifi. The lifi market was projected to have a compound annual growth rate of 82% from 2013 to 2018 and to be worth over $6 billion per year by 2018. However, the market has not developed as such and lifi remains with a niche market, mainly for Technology evaluation. n terms of its end use the technology is similar to wifi. The key technical difference is that wifi, uses radio frequency to transmit data. 

 picture  

According to figure up, lifi technology consist of LED lamp as the media transmission and photo detectors as a receiver of transmitted data. Lamp driver is needed to make LED working properly. While amplification and processing are responsible  to manage the signal that comes from the photo detector.

  Mobile Communication                                                                      

 Mobile two-way radios are one to many communication systems that operate in half-duplex mode. i.e. Push to talk. The most common among this type is citizen band (CB) radio, which uses amplitude medulation (AM). It operates in the frequency range of 26-27.1 MHz having 40 channels  of 10 KHz. It is a non-commercial service that uses a press to talk switch. It can be amplitude modulated having double sideband suppressed carrier or single sideband suppressed carrier. Mobile telephones offer full-duplex transmission. These are one-to-one system is that permit two simultaneous transmissions. For privacy each mobile unit carries a unique telephone number.

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