Using visible light to make your objects smarter : from the laboratory to your home

Workshop sur Visible Light Communication au SIDO 2016

Transcript

1. Visible Light Communication Using visible light to make your objects smarter : from the laboratory to your home
2. What is Visible Light Communication (VLC) • Communication with lights → Invisible : Infrared (IR) → Visible : plain lights LED used for illumination • Advantages of visible light → Alleviates the radio spectrum congestion → Can offer bit rates larger GBit/s → Allow more intense channel reuse → Do not produce any harmful side effect → Lights are already present indoor
3. What is Visible Light Communication (VLC) • High bit rates → LIFI : bidirectional, visible light + IR → Alternative to Wifi → Few Gbps in the labs → Commercial products offers 40 Mbps • Low bit rates → Low cost and low power → Few hundred of bit/s → LED-to-LED → LED-to-Camera → Screen-to-PD/Camera
4. Why VLC for the Internet Of Things ? • How to avoid congesting networks ? • How to use efficiently the limited battery energy in the objects providing wireless connectivity ? • How to reduce production costs ? • connected devices => available radio spectrum
5. Which use cases of VLC for the Internet Of Things ? • Device to device : vehicular network, network of toys • Infrastructure to device : robots, cars. • Infrastructure to end-user : indoor localisation • Device to end-user : with the smartphone, near field com.
6. VLC & smartphone • With the Audio Jack → Small circuit with a photodiode → Bit rates limited by the smartphone audio sampling → Noise and smartphone orientation sensible • Light Sensor → Very (very) low bit rates : few bits/s → Location at the light bubble level • Camera → Exploit the CMOS sensors Rolling Shutter Effect → Both Line-Of-Sight & Non-Line-Of-Sight → Few kbit/s → MIMO → Accurate localization using photometry
7. Indoor Localization • A $5Billions market in 2018 1 • Retails → Where am I ? Where are these cans of coca ? → Push / Pull offers and extra information • Visually impaired people → Indoor navigation • Contextual information → Museum • Indoor autonomous vehicle guidance → Industrial robots → Warehouses and manufacture plans 1 ABI Research’s, “Indoor Location in Retail: Where Is the Money?”
8. • Often with radio → Ultra Wide Band (Decawave) → Wifi (RADAR) → Bluetooth LE (iBeacons) → RFID • Ultrasound • Average precision about 1-5 meters • Some inconvenients → Radio waves … → Need a dedicated infrastructure → No Orientering Indoor Localization
9. • LED ID → ByteLight : retail, with Bluetooth LE Beacons → Philips : Carrefour Hypermarket → Oledcomm : and the Museum of Playing Card, Issy • RSSI and trilateration → Needs additional hardware and photodiode → Sub-meter accuracy • Using Photometry → With the smartphone camera → Average precision up 10 centimeters → Offers orientering up to 4° Indoor Localization with VLC
10. Demo VLC Temperature Sensor
11. Bill Of Materials : BLE vs VLC temperature sensor • Bluetooth Low Energy → Full BOM : 9.75€ • Visible Light → Full BOM : 7.25€ 25% Cheaper Easier integration
12. VLC Temperature Sensor 01 01 10 01 10 10 01 111 01 01 011 001 011 ...
13. • Line Of Sight & Asynchronous • CMOS sensor Rolling Shutter Effect • 6kHz Optical Clock Rate → Limited by camera min. Exposure Time • Manchester Encoding → Ensure 50% Duty Cycle • SS + 12 bits packet + CRC → Synchronization Symbol VLC Temperature Sensor
14. Future of Visible Light Communication • VLC needs protocols → For efficient broadcasting → Variable capacity and lossy link → Heterogeneous network (5G) • VLC needs a standard → 802.15.7 is outdated and unused → To address low and high bit rates → To support differents kind of receiver/emitter → Work In Progress => 802.15.7r1 • VLC needs a killer application