Question 42 from UPSC CSE 2016 - Science and
Technology

Question

With reference to 'LiFi', recently in the news, which of the following statements is/are correct?
1. It uses light as the medium for high-speed data transmission.
2. It is a wireless technology and is several times faster than 'WiFi'.
Select the correct answer using the code given below.

IASCODEX · Accepted Answer

Correct Option: C. Both 1 and 2

Strategy: Analyze the term 'LiFi' to deduce its core characteristics. The name 'Light Fidelity' confirms light as the data transmission medium. Its context as a WiFi alternative establishes it as a wireless technology. Its status as a newer technology implies it offers higher speeds, leveraging the wider visible light spectrum.

Key Info: LiFi (Light Fidelity) is a bidirectional, high-speed wireless communication technology that uses visible light communication (VLC) to transmit data between devices. It was coined by Professor Harald Haas of the University of Edinburgh in 2011.

- **Mechanism**: LiFi uses light-emitting diodes (LEDs) to transmit data through rapid, imperceptible flickering of light. The light source acts as a router, and a photo-detector on the receiving device converts these light variations back into electrical signals.
- **Medium**: It primarily uses the visible light spectrum (400-800 THz), which is approximately 10,000 times larger than the radio frequency spectrum used by Wi-Fi.
- **Comparison with Wi-Fi**:
  - **Wireless**: Both LiFi and Wi-Fi are wireless technologies.
  - **Speed**: LiFi offers significantly higher speeds (theoretically up to 100 Gbps), often several times faster than Wi-Fi, due to the much wider bandwidth of the visible light spectrum.
  - **Security**: LiFi is inherently more secure as light cannot penetrate opaque walls, making eavesdropping from outside a room impossible. This creates 'light cells' where data transmission is confined.
  - **Interference**: It does not interfere with radio frequency systems, making it suitable for environments sensitive to electromagnetic interference (e.g., hospitals, aircraft).
  - **Ubiquity**: Utilizes existing lighting infrastructure (LEDs), making deployment potentially widespread.
  - **Line of Sight**: Requires a direct line of sight or reflected light path, which can be a limitation for mobility compared to Wi-Fi's wider area coverage through radio waves.
- **Applications**: LiFi holds promise for applications in smart homes, smart cities, healthcare (hospitals), aviation (in-flight entertainment), hazardous environments (where radio frequency signals are problematic), and underwater communication.

IASCODEX · Answer

Option A: 1 only

IASCODEX · Answer

Option B: 2 only

IASCODEX · Answer

Option D: Neither 1 nor 2

With reference to 'LiFi', recently in the news, which of the following statements is/are correct? It uses light as the medium for high-speed data transmission. It is a wireless technology and is several times faster than 'WiFi'. Select the correct answer using the code given below.

With reference to 'LiFi', recently in the news, which of the following statements is/are correct?

It uses light as the medium for high-speed data transmission.

It is a wireless technology and is several times faster than 'WiFi'.
Select the correct answer using the code given below.