FSO: Wireless Transmission By Light Beam
- Sylvia Rose
- Mar 29
- 4 min read
Updated: Mar 30
Free-space optical (FSO) systems use light beams to transmit data. Known for high bandwidth, security and immunity to electromagnetic interference, they're a rising alternative to traditional radio frequency communication.
About FSO
Traditional wired and radio frequency (RF) systems have limitations as in bandwidth, security and susceptibility to interference. Free-Space Optical communication provides high bandwidth and immunity to electromagnetic (EM) interference.
FSO systems, also known as optical wireless communication (OWC), use light beams, specifically lasers, to send data through the atmosphere. Lasers can carry information over long distances.
Lasers carry electrical signals by transforming them into optical signals (light) for transmission, and then converting them back into electrical signals at the destination. This is the usual method for laser communication and fiber optic networks.
FSO is used in locations where installing fiber-optic cables is impractical or cost-prohibitive. This method reaches data rates comparable to and surpassing fiber-optic systems, ranging from 1 Gbps to 10 Gbps.
Gbps, or gigabits per second, is a unit used to measure speed at which data is transferred across a network. It describes internet speed or network capacity, defining how many billion bits of data can be sent in one second.
Advantages of FSOs
Ultra-High Bandwidth
FSO systems achieve bandwidths surpassing fiber optic cables. This is due to the high frequency of light, which enables transmission of large files in a short time. FSOs are suited for video streaming, high-resolution imaging and large data transfers.
Security
RF signals can be intercepted and jammed. FSO beams are directional and require a precise line-of-sight connection. This makes it hard for unauthorized parties to tap into the communication link.
Encryption methods can also be used in FSO systems. FSO can apply methods similar to those used in fiber-optic communications encryption, adding further layers of security.
Electromagnetic Interference
RF communication is plagued by interference from other devices on similar frequencies. FSO is virtually immune to EM interference. It uses the optical spectrum. This is especially valuable in hospitals, military operations and regions with heavy radio frequency interference, like urban centers.
Rapid Deployment & Low Cost
Compared to laying fiber optic cables, FSO systems are faster and less expensive. Installation is a matter of mounting transceiver units and aligning the optical beams.
This eliminating need for trenching, permits and infrastructure costs. Rapid deployment capability makes FSO suited for temporary installations or situations where laying cables isn't practical.
Uses
Last-Mile Connectivity: FSO bridges the gap between high-speed fiber optic networks and end-users. Telecom operators use FSO technology to complement existing fiber-optic networks.
With last-mile connectivity FSO reaches remote areas, and avoids the congestion of densely populated urban centers.
Enterprise Connectivity: FSO enables seamless connectivity between buildings in a corporate campus or metropolitan areas to eliminate need for leased lines or complex RF networks. Cities increasingly adopt FSO systems for urban networking.
Mobile Backhaul: FSO provides a high-bandwidth, low-latency solution for connecting cellular towers to the core network, supporting the growing demands of 4G and 5G mobile data services.
Disaster Recovery: FSO can establish communication links in regions of disaster to connect with emergency responders and relief efforts. During natural disasters like hurricanes or earthquakes, these systems help coordinate rescue efforts, transmitting data at up to 1 Gbps.
Military and Defense: FSO is ideal for secure communication in military and defense. Data privacy and resistance to jamming are rather important. However, secure technologies are only as smart as people who use them, as evidenced by recent bumbles of the US War Department.
Problems
Atmospheric Attenuation: Rain, fog, snow, atmospheric turbulence and other factors like air pollution can scatter and absorb the light beam, to reduce signal strength and potentially interrupt communication.
Line-of-Sight Obstruction: FSO requires a clear line of sight between the transmitter and receiver. Obstructions like buildings, trees or moving vehicles block the beam and disrupt the connection.
Fixes
Adaptive Optics (currently used): Techniques to compensate for atmospheric turbulence and maintain a stable beam path.
Multi-Beam Systems: Using multiple beams to increase redundancy and improve link availability in bad weather.
Advanced Modulation Techniques: Using modulation schemes less susceptible to signal degradation.
Hybrid FSO/RF Systems: Combining FSO with RF communication for a resilient hybrid.
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