Light Fidelity (LiFi)

Introduction

LiFi (Light Fidelity) is a wireless communication technology that uses visible light, particularly LED bulbs, to transmit data. It was first demonstrated in 2011 by Professor Harald Haas from the University of Edinburgh, Scotland, who also coined the term LiFi. It provides high-speed, bidirectional, networked mobile communication in a similar manner as WiFi but with higher speeds, lower latency, and a larger bandwidth (thousands of terahertz).

Intro 2

LiFi has the advantage of being useful in electromagnetic-sensitive areas like aircraft cabins, hospitals, and nuclear power plants without causing electromagnetic interference. Its utilisation of unused visible lights in human life has opened up new opportunities in wireless communications technology.

How does LiFi Work?

• LED modulation - LiFi uses LED bulbs that can be switched on/off rapidly to transmit data through visible light communication (VLC) by modulating light.
• Transmitter encoding - A LiFi transmitter has an LED driver that encodes binary data into on-off light signals. The data rate is varied by changing the flickering rate.
• Receiver decoding - A LiFi receiver photodiode
  detects light intensity changes caused by objects blocking the beam and
  converts them back into the original data stream.
• Bidirectional communication - uplink transmitter
  close to the photodiode modulates the receiver's LED light to transmit
  data back, forming a bidirectional channel.
• Operating light frequencies - A visible light spectrum from 430 to 770 THz is most suitable for LiFi, as photodiodes are highly sensitive in this range. Infrared or ultraviolet can also be used.

• Components of LiFi

  • LED transmitter: An LED lamp emits modulated
    visible light which acts as a data transmission medium. Standard
    high-brightness white LEDs can be used for better coverage area and
    illumination.
  • Photodiode receiver: Photodiodes sense the
    transmitted light signals, which are then demodulated to extract the
    encoded data. High-sensitivity avalanche photodiodes offer high data
    rates.
  • Controller circuit: These circuits drive the LEDs for modulation and manage the timing of data transmission.
  • Software stack: It handles aspects like encoding,
    error control, encryption, and connectivity at the transmitter. Decoding
    and error correction are done at the receiver.

  • LiFi Ecosystem

    

    Significance of LiFi

    • High speeds: LiFi can provide internet speeds over 100 Gbps, which is much faster than WiFi. This can enable high-speed applications.
    • Security: Light cannot penetrate through walls that contain data within a closed area making it more secure.
    • Decentralised means of communication: LiFi is a decentralised means of providing communication due to its working and components. Combined with blockchain technology, it can
      revolutionise the data transfer and communication technology with a
      quick and secure distributed system of transactions.
    • No electromagnetic interference: LiFi uses visible light which does not cause electromagnetic interference. This allows its use in sensitive areas like aircraft and hospitals.
    • High density: The visible light spectrum has 10,000 times more bandwidth than radio waves, thus it does not have the problem of ‘spectrum crunch’, as with the radio waves.
    • AR/VR: LiFi helps overcome technology challenges
      due to non-interference from other EM Waves and being faster, which
      allows Virtual Reality and Augmented Reality products to become wireless
      and reliable.
    • Environmentally friendly: LiFi uses energy-efficient LED bulbs to transmit data. Being highly energy efficient, it results in lower carbon emissions.
    • Cheaper deployment: LiFi can be implemented simply by installing LED bulbs. No new wiring or infrastructure is required making it easy to deploy.
    • Prevention of "dead zones": LED bulbs ensure that there are no dead zones as is the case with WiFi routers. Light can easily reach areas inside buildings where radio waves cannot penetrate.

    • LiFi vs WiFi

      

      Applications of LiFi Technology

      Secure and High-speed broadband: LiFi can provide high
      bandwidth wireless connectivity in indoor spaces such as offices, malls,
      railway stations and aircraft cabins.

      • Remote connectivity: LiFi can provide connectivity
        in rural areas where laying fibre optic cables is difficult. It is also
        suitable for remote hilly areas with no cellular or network
        availability.
      • Cellular offloading: The load on cellular networks can be reduced by offloading data to optimally placed LiFi networks.
      • Vehicles: LiFi is being tested in vehicles for
        inter-vehicular and vehicle-to-infrastructure communication, collision
        avoidance and autonomous driving.
      • Aviation: It provides high-speed in-flight connectivity for passengers using cabin overhead lights. Reduces aircraft wiring weight.
      • Disaster management: It facilitates high-speed
        optical wireless communication using LiFi and is resilient in case of
        disasters that damage cellular networks.
      • Smart lighting: The future smart lighting with LEDs
        and LiFi will combine illumination, data connectivity and sensing
        making cities more efficient.
      • Wireless charging: LiFi bulbs can provide wireless charging to devices using resonant inductive coupling along with high-speed data transmission.
      • Next-generation networks: 5G networks and beyond
        will incorporate LiFi to provide ultra-high capacity in dense spaces and
        relieve the load on radio networks.
      • Internet of Things:
        LiFi is ideal for smart devices and machine-to-machine communication in
        enclosed industrial and manufacturing environments with multiple
        sensors.
      • Defence and security: It provides high-speed
        secured wireless communication in border areas, sensitive government
        installations, and warships that can be enabled by LiFi networks.
      • 

      • Challenges for LiFi Adoption

        • Needs line-of-sight: The dependency on the line-of-sight constrains its application in a limited area only.
        • Needs unmodulated ambient light: Interference from sunlight and ordinary bulbs may affect the quality of transmission. Filters may be required.
        • Device incompatibility: Many existing devices do
          not have the inbuilt capability to connect to LiFi networks. Dongles or
          integrated receivers will be essential.
        • Initial high costs: Currently, LiFi equipment costs are higher than WiFi but are likely to fall with economies of scale and technology maturity.
        • Dependency on lighting infrastructure: Data networks remain affected by faults or switching off lighting systems, unlike WiFi, which is independent.
        • Security concerns: Research shows LED bulb outages
          can be intentionally created to form covert channels for data
          exfiltration affecting confidentiality.
        • Standardisation: Multiple fragmented LiFi standards
          currently exist. Harmonization into open, unified standards is
          important for interoperability.
        • Health concerns: While believed to be safe, the long-term impacts of prolonged human exposure to flickering LED lights used in LiFi remain unknown.
        • Latency: Currently, LiFi has a higher latency compared to WiFi networks, but ongoing enhancements are lowering delays. Ultra-low latency is needed for applications like vehicular communications.