IEEE P802.11 Wireless LANs Light Communications (LC) for 802.11: Draft response to the Technical Feasibility Questions Date: 2017-02-20 Author(s): Name Affiliation Address Phone email Dobroslav Tsonev pureLiFi Nikola Serafimovski pureLiFi LC Technical Feasibility How does LC work? Any baseband electrical signal that is supplied to a light-emitting diode (LD) generates a light output with intensity proportional to the amplitude of the electrical signal. As a diode only works for positive current/voltage, the electrical signal needs to be positive only. Bipolar communication signals are typically realized around a positive bias (operating) point for which the LED/LD is active and has a linear input-output characteristic. The relationship between voltage and current is somewhat linear, but the current-to-light relationship of the device is typically more linear. As a result, the information is typically encoded into the current of the electrical signal used to drive the LED/LD. The LED/LD diode effectively serves the purpose of an upconverter that generates light-frequency waves with intensity proportional to the electrical current that flows through the device. The spectrum of the electromagnetic radiation is not correlated with the information signal and is dependent on the material/physical implementation of the LED/LD. For LEDs, this spectrum is typically very wide, while for LDs it is typically much narrower, yet still quite wider than the bandwidth of the baseband information signal itself. [1,2] Any light that is incident on a photodetector such as a photodiode leads to current flowing through the device, which is proportional to the light intensity. As a result, a photodiode converts light variations into current variations or a light information signal into a current information signal. The current information signal is then treated as any other electrical baseband information signal in a communication system. [1,2] How does LC work in a bright room with sunlight?
IEEE P802.11 Wireless LANs Light Communications (LC) for 802.11: Draft response to the Technical Feasibility Questions Date: 2017-02-20 Author(s): Name Affiliation Address Phone email Dobroslav Tsonev pureLiFi Nikola Serafimovski pureLiFi LC Technical Feasibility How does LC work? Any baseband electrical signal that is supplied to a light-emitting diode (LD) generates a light output with intensity proportional to the amplitude of the electrical signal. As a diode only works for positive current/voltage, the electrical signal needs to be positive only. Bipolar communication signals are typically realized around a positive bias (operating) point for which the LED/LD is active and has a linear input-output characteristic. The relationship between voltage and current is somewhat linear, but the current-to-light relationship of the device is typically more linear. As a result, the information is typically encoded into the current of the electrical signal used to drive the LED/LD. The LED/LD diode effectively serves the purpose of an upconverter that generates light-frequency waves with intensity proportional to the electrical current that flows through the device. The spectrum of the electromagnetic radiation is not correlated with the information signal and is dependent on the material/physical implementation of the LED/LD. For LEDs, this spectrum is typically very wide, while for LDs it is typically much narrower, yet still quite wider than the bandwidth of the baseband information signal itself. [1,2] Any light that is incident on a photodetector such as a photodiode leads to current flowing through the device, which is proportional to the light intensity. As a result, a photodiode converts light variations into current variations or a light information signal into a current information signal. The current information signal is then treated as any other electrical baseband information signal in a communication system. [1,2] How does LC work in a bright room with sunlight?