Lighting and Full-Duplex Communication using Optical LED technology Charles Lim Nov. 24, 2003 Dr. Fernando EE8114

The LED Advantage Consumes only one fourth or less power than incandescent bulbs. Consumes only one fourth or less power than incandescent bulbs. 25,000 to 50,000 continuous hours of life 25,000 to 50,000 continuous hours of life No RF EMI No RF EMI Very secure compared to RF Very secure compared to RF Robust compared to other lighting devices Robust compared to other lighting devices High data rate capability High data rate capability

Design Proposal

How to modulate the LED w/ Data? PLC (Power Line Communications) PLC (Power Line Communications) Use existing power outlets that act similarly to data ports and networks throughout the house to transfer data from the computer to the LED system Use existing power outlets that act similarly to data ports and networks throughout the house to transfer data from the computer to the LED system Currently only support low data rates (i.e. a few hundred kbps) Currently only support low data rates (i.e. a few hundred kbps) Easy to install and cheaper for already installed houses Easy to install and cheaper for already installed houses PLC (Power Line Communications) PLC (Power Line Communications) Use existing power outlets that act similarly to data ports and networks throughout the house to transfer data from the computer to the LED system Use existing power outlets that act similarly to data ports and networks throughout the house to transfer data from the computer to the LED system Currently only support low data rates (i.e. a few hundred kbps) Currently only support low data rates (i.e. a few hundred kbps) Easy to install and cheaper for already installed houses Easy to install and cheaper for already installed houses CPU PLC Modem Power outlet BPF Picks up the data AC/DC Tx LEDs & IR Rx Rx LEDs & IR Tx Demodulator Mobile Terminal CPU PLC Modem Power outlet BPF AC/DC Tx LEDs & IR Rx Rx LEDs & IR Tx Demodulator Mobile Terminal

Optical Fiber Communications Optical Fiber Communications Expensive to install for already built houses. Expensive to install for already built houses. Capable of carrying tremendously high data rates Capable of carrying tremendously high data rates Almost unlimited bandwidth for the home user for both optical wireless (LED) and optically connected (fiber) wired applications Almost unlimited bandwidth for the home user for both optical wireless (LED) and optically connected (fiber) wired applications Better option for pre-built houses where installation of fiber will be easier. Better option for pre-built houses where installation of fiber will be easier. CPU E-O converter BPF Data used to modulate the power AC/DC Tx LEDs & IR Rx Rx LEDs & IR Tx Demodulator Mobile Terminal CPU Fiber connector BPF AC/DC Tx LEDs & IR Rx Rx LEDs & IR Tx Demodulator Mobile Terminal Fiber connector O-E converter Power outlet

Factors affecting LED systems Thermal Temperature Thermal Temperature Packaging Type and System Integration Packaging Type and System Integration Multi-path Dispersion Multi-path Dispersion Reflectivity of the Room Reflectivity of the Room Downlink/Uplink Data rate Downlink/Uplink Data rate LED Power LED Power Need for Channel Equalizer Need for Channel Equalizer

Thermal Management Thermal Management For LEDs to achieve long lifetimes in the range of 25,000 to 50,000 hours, the temperature of the junction must be under 75°C. For LEDs to achieve long lifetimes in the range of 25,000 to 50,000 hours, the temperature of the junction must be under 75°C. Also, once the junction temperature reaches over 125°C, problems with LEDs become a lot more common. Also, once the junction temperature reaches over 125°C, problems with LEDs become a lot more common. Packaging Type Packaging Type Current packages have 300°C. Current packages have 300°C. If assume room temperature 25°C, then minimum package thermal resistance is 50°C. If assume room temperature 25°C, then minimum package thermal resistance is 50°C. System Integration System Integration Unlike incandescent bulbs, LEDs do not radiate wasted heat away from the part. It requires the device be properly cooled. Unlike incandescent bulbs, LEDs do not radiate wasted heat away from the part. It requires the device be properly cooled. Design and installation of not only LEDs but the cooling system is critical as well for LED systems. Design and installation of not only LEDs but the cooling system is critical as well for LED systems.

Multi-Path Dispersion Multi-Path Dispersion Main issue in optical wireless technology Main issue in optical wireless technology Due to the large amount of lighting LEDs Due to the large amount of lighting LEDs Minimal interference from the white LEDs and IR LED due to spectral separation Minimal interference from the white LEDs and IR LED due to spectral separation Photodiodes also has spectral separation to minimize interference Photodiodes also has spectral separation to minimize interference IR and LED Tx linewidth chosen such that minimal interference with photodiodes. IR and LED Tx linewidth chosen such that minimal interference with photodiodes. Reflectivity of the room Reflectivity of the room Higher reflectivity means more dispersion Higher reflectivity means more dispersion Depends on color and reflectivity of materials inside room Depends on color and reflectivity of materials inside room Downlink/Uplink data rate Downlink/Uplink data rate Receiver and LED system circuitry determined by the downlink bandwidth Receiver and LED system circuitry determined by the downlink bandwidth Downlink easier to design, larger power from lighting LEDs Downlink easier to design, larger power from lighting LEDs Uplink data rate cannot be very high due to limited IR power Uplink data rate cannot be very high due to limited IR power Uplink bandwidth restriction determined by IR transmitter and receiver design. Uplink bandwidth restriction determined by IR transmitter and receiver design. Higher data rates = Higher Cost Higher data rates = Higher Cost

LED Power LED Power Higher Power allows for faster data rates Higher Power allows for faster data rates Limitations in power output design due to government restrictions Limitations in power output design due to government restrictions Channel Equalizer Channel Equalizer To achieve better data rates and reliability a dynamic channel equalizer is required. To achieve better data rates and reliability a dynamic channel equalizer is required. Use LMS digital signal processing algorithm Use LMS digital signal processing algorithm LMS block is right after modulator and demodulator for both IR and light LEDs LMS block is right after modulator and demodulator for both IR and light LEDs Dynamically adjust downlink/uplink bit rates depending on current room BER Dynamically adjust downlink/uplink bit rates depending on current room BER Increases reliability of system Increases reliability of system Mobility is increased Mobility is increased Higher Efficiency Higher Efficiency

Signal Interferences

Simple RS232 LED Downlink System Part of the project is to demonstrate a simple LED system and to prove it is feasible Part of the project is to demonstrate a simple LED system and to prove it is feasible TX Circuit TX Circuit Consists of 10 super bright white LEDs driven by a 5V DC power supply and modulated by a RS232 Line Driver IC connected to a computer serial port. Consists of 10 super bright white LEDs driven by a 5V DC power supply and modulated by a RS232 Line Driver IC connected to a computer serial port. RX Circuit RX Circuit Consists of 3 visible light photodiodes and a comparator which detects optical signals and converts it to rs232 voltage levels Consists of 3 visible light photodiodes and a comparator which detects optical signals and converts it to rs232 voltage levels TX RX White LEDs Detecto r Circuit FREE SPACE

Conclusion This project achieves Lighting and communication using Optical wireless communication. This project achieves Lighting and communication using Optical wireless communication. Through more research and design, optical wireless communications will eventually achieve: Through more research and design, optical wireless communications will eventually achieve: Reliable high data rate transfers Reliable high data rate transfers No RF interference No RF interference Mobility and security Mobility and security Minimal multi-path distortion Minimal multi-path distortion Higher power efficiency, lower transmit and receive power Higher power efficiency, lower transmit and receive power Integrating Lighting and communication for home Integrating Lighting and communication for home

Conclusion…… Future of Wireless communication ……….

References [1] Bala Balasingam, Charles Lim, Gajendran Wignarajah, Jeyacanthan Nesarajah, Sarmila Selvaratnam, “Lighting and Communication from the same source”, 2003 ICUE (International Conference for Upcoming Engineers) [1] Bala Balasingam, Charles Lim, Gajendran Wignarajah, Jeyacanthan Nesarajah, Sarmila Selvaratnam, “Lighting and Communication from the same source”, 2003 ICUE (International Conference for Upcoming Engineers) [2] Toshihiko Komine, Masao Nakagawa, “Integrated system of white LED visible- light communication and power-line communication”, 2002 IEEE [2] Toshihiko Komine, Masao Nakagawa, “Integrated system of white LED visible- light communication and power-line communication”, 2002 IEEE [3] Yuichi Tanaka, Shinichirou Haruyama, Masao Nakagawa, “Wireless Optical Transmissions with white colored LED for Wireless Home Links”, 2000 IEEE [3] Yuichi Tanaka, Shinichirou Haruyama, Masao Nakagawa, “Wireless Optical Transmissions with white colored LED for Wireless Home Links”, 2000 IEEE [4] Tsunemasa Taguchi, Yamaguchi University, “Light Gets Solid”, OE Magazine, The Monthly Publication of SPIE October 2003 [4] Tsunemasa Taguchi, Yamaguchi University, “Light Gets Solid”, OE Magazine, The Monthly Publication of SPIE October 2003 [5] Srinath Aanegola, Jim Petroski, Emil Radkov, GELcore LLC, “Let There Be Light”, OE Magazine, The Monthly Publication of SPIE October 2003 [5] Srinath Aanegola, Jim Petroski, Emil Radkov, GELcore LLC, “Let There Be Light”, OE Magazine, The Monthly Publication of SPIE October 2003