RFRF vs FSO: Understanding the Key Differences
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This page compares RF vs FSO and mentions the difference between RF and FSO (Free Space Optics).
Introduction
Both RF (radio frequency) and FSO (Free Space Optics) are used in un-guided systems for wireless communication.
What is RF?
The term RF refers to Radio Frequency. It ranges from 3 KHz to 300 GHz. It finds applications in various domains other than wireless communication such as in the medical domain for skin tightening, cancer treatment, vision correction, and so on. It is also used for mobile, radio, and television broadcasting.
The figure depicts the use of RF in satellite communication, microwave, cellular systems, and wifi systems (based on the IEEE 802.11 WLAN standard). As shown, RF requires an antenna for the transmission and reception of EM (Electromagnetic) waves.
What is FSO?
It is a wireless technology that transmits data via laser beams. It uses light waves to transmit data between buildings which have a clear LOS (line of sight). The difference between OFC and FSO is that OFC (Optical Fiber Communication) sends data via light through “fiber” whereas FSO (Free Space Optic) communication sends data via light through “air”.
Following points summarize the working of the FSO system as per the block diagram.
- Information or data traffic is converted into pulses of invisible light which represent binary 1’s and 0’s.
- The transmitter transmits light pulses into the air. It uses an LED or Laser Diode (LD).
- The receiver at the other end collects the light using lenses and/or mirrors. It uses a photo-detector.
- The received signal is processed and converted back into the transmitted information.
Difference between RF vs FSO
The following table compares RF versus FSO and mentions the difference between RF and FSO.
| Specifications | RF | FSO |
|---|---|---|
| Frequency range | 3 KHz to 300 GHz | > 300 GHz |
| Bandwidth | Lower as the frequency spectrum in the air is a scarce resource. | Much higher, Tb/s throughput can be achieved in a single FSO channel |
| Spectrum | RF spectrum is a scarce resource and regulated for allocation as per need. | It is large and license-free. |
| Installation | Difficult | Moderate |
| Data Rate | Mbps to Gbps | Gbps to Tbps |
| Connectivity | P2P short reach (Example Microwave radio) | P2P, P2MP short and long Reach |
| Multi-path fading | Affected | Not affected |
| Security | Poor, It is less secured as RF waves are susceptible to eavesdropping. | Good, It is very difficult to intercept and hence it is highly secured. |
| Components | Larger in size | Smaller in size |
| Atmospheric loss | Affected by rain | Affected by rain, moreover RF signal gets attenuated due to signal absorption by gases such as O2 and H2O. |
| Interference from EM waves | Affected | Immune |
| Side lobes | Present | Not present |
Conclusion
In order to leverage the benefits of both RF (Radio Frequency) and FSO (Free Space Optics), combined hybrid RF/FSO-based communication technologies have been developed. RF links complement FSO links to achieve carrier class availability of 99.999%.
