Lifi vs Gifi

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LiFi Technology

Li-Fi internet architecture

Following are the features of LiFi technology as depicted in the figure-1.
• LiFi (Light Fidelity) works based on VLC (Visible Light Communication) principle.

• LiFi transmits data using light intensity modulation.
• It uses LEDs at transmit ends and Photo-detectors at receive ends. LiFi dongle uses photo-detectors as shown in the figure-1. Here LEDs are connected with internet server via lamp driver for internet connection.
• It uses light with wavelength ranging from 380 nm to 780 nm for data communication between LEDs and photo detectors.
• LiFi system supports three modes viz. peer to peer, star and broadcast.
• LiFi system uses modulation schemes such as OOK, VPPM, CSK.
• The PHY and MAC layers of LiFi system are defined in IEEE 802.15.7-2011 standard.
• LiFi technology is used for various applications which include street lights, sign boards, internet etc. • It transfers data very rapidly and securely due LOS (Line of Sight) operation of optical signals.

GiFi Technology

Following are the features of GiFi technology.
• It is first transceiver in the world developed on single chip using CMOS process.
• It operates at 60 GHz. (uses unlicensed band from 57 to 64 GHz).
• It allows wireless transfer of audio/video at 5 Gbps within coverage of 10 meters with very low power consumption.
• It is developed by NICTA (National Information and Communication Technology Research Center), Australia.
• The main component of gifi architecture is subscriber station which interfaces with several APs (Access Points).
• It is defined in IEEE 802.15.3C standard. It forms wireless PAN network in millimeter wave frequency band.
• Antenna is usually mounted on the roof which supports LOS communication.
• It uses TDD topology for transmission and reception with single antenna.
• It can be used with FDD topology using two antennas.
• Advantages: It offers very high data rate (7Gbps, BPSK) and low interference. Complex modulation schemes are not required. Antenna separation of about 1.25 mm is needed. Gifi technology is about ten times fast compare to wifi technology.
• Disadvantages: It supports short distance (about 10 meters) due to high attenuation which depends on frequency. It can be blocked by an object very easily. RTS/CTS does not work in gifi technology unlike wifi.


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