Chad WeissJoseph Courtright

Free Space Optics Communication

Free Space OpticsOr Fiber Optics Without The Fiber

How FSO works

Laser: Generate Light Pulse

Lens:Focuses Light Into

Beam

Shoots the beam over the air

Lens:Gathers Light Beam

Photoreceptor:Turns Light To Electric

Signals

Modulate Electric Signal:Powers laser system

Technological ComparisonFree Space Optics Fiber OpticsHigh data rate

Vulnerable to Weather Conditions

High date rate

Requires Expensive Infrastructure

Technological ComparisonFree Space Optics RF WirelessHigher data rate

Vulnerable to Weather Conditions

More Difficult To Tap/Spy On

More Power Efficient

Lower date rate

Vulnerable to RF Interference

Frequency Regulated

ApplicationsSatellite CommunicationCommunication between cell towersSending TV signalsLast Mile Problem

Last Mile Problem

Fast Fiber Optics Connection

Slow Copper Cable Connection Destination

DataFrom Really Far Away

Within a mile of destination

Space Photonic LaserFireFSO communication systemHighly SecureUltra-High Wireless

BandwidthAutomatic Tracking,

Acquisition and Pointing System (TAP)

Fast Continuous Link Synchronization

Operates in the Near Infrared Spectrum (1550 nm)

High fidelity, 1 Gbps data rates at distances up to 5 km

Design ChallengesAdverse Weather ConditionsAtmospheric Turbulence Atmospheric Attenuation

Atmospheric Turbulence

Atmospheric AttenuationScattering Absorption

System SolutionsDesign Challenge Mitigation

TechniqueJustification

Atmospheric Turbulence

Aperture Averaging Increasing the receiver aperture creates a larger acceptance angle which can help average out the fast fluctuations, or scintillations, caused by eddies, thus reducing channel fading.

Atmospheric Turbulence

Adaptive Optics A closed loop feedback system compensates for the beam misalignment due to turbulence.

Atmospheric Turbulence

Adaptive Thresholding

Coding and modulation techniques can be used to simplify the detection of a 1 or 0 at the receiver. If dispersion or scintillation were to occur, adaptive thresholding could clean up the BER of the system.

System SolutionsDesign Challenge Mitigation

TechniqueJustification

Solar Interference Background Noise Rejection

Spatial filters and modulating techniques with high peak-to-average power could eliminate any noise entering the receiver.

Atmospheric Attenuation

Hybrid RF/FSO If weather conditions make it impossible for FSO communication, the system could switch to a backup RF.

Bit Errors Packet Re-transmission

Re-transmission protocols such as automatic repeat request (ARQ) can improve the overall performance of the link.

Line-of-Sight (LOS) Obstructions

Reconfiguration / Rerouting

Path configuration and data rerouting is issued in order to increase the reliability and availability of the link.

Other Quality of Service Control

Implementation of routing protocols and control algorithms can be used to improve the overall quality of the service being provided by measuring the data rate, latency, delay jitter, data loss, energy consumption, reliability and efficiency.

PropositionHybrid Radio Frequency (RF)/FSOProgrammable Logic Controller (PLC)

Questions?