modBulb: A modular Light Bulb for Visible Light Communication Kasun - - PowerPoint PPT Presentation

▶

Mar 17, 2023 281 likes •451 views

modBulb: A modular Light Bulb for Visible Light Communication Kasun Hewage 1 , Ambuj Varshney 1 , Abdalah Hilmia 1 , Thiemo Voigt 1 , 2 1 Uppsala University, Sweden 2 SICS Swedish ICT, Sweden October 3, 2016 Embedded Visible Light Communication

SLIDE 1

modBulb: A modular Light Bulb for Visible Light Communication

Kasun Hewage 1, Ambuj Varshney 1, Abdalah Hilmia 1, Thiemo Voigt 1,2

1Uppsala University, Sweden 2SICS Swedish ICT, Sweden

October 3, 2016

SLIDE 2

Embedded Visible Light Communication

VLC has been mainly researched as an alternative to WiFi

– High bitrates in the orders of GBit/s

Embedded Visible Light Communication

– Not all applications require high bitrates – Internet connectivity is only one application

Embedded VLC applications

– Localization – Gesture Recognition – Camera Flash Synchronization

K. Hewage, A. Varshney, A. Hilmia, T. Voigt

modBulb: A modular Light Bulb for VLC 2

SLIDE 3

Motivation

Light transmitter is a key component in VLC

– Decides light intensity, data rate, etc

Lack of truly open source hardware

– Repeatability of experiments

Existing solutions: OpenVLC [HotWireless 2015], Linux Light Bulbs[VLCS 2015]

– Limited bandwidth – Not very flexible (eg: multiple LEDs, LEDs with different wavelengths)

Can we design an open VLC hardware to enable a wide spectrum of applications?

K. Hewage, A. Varshney, A. Hilmia, T. Voigt

modBulb: A modular Light Bulb for VLC 3

SLIDE 4

Contributions: modBulb

Flexible baseband generator

– MCU, FPGA or a hybrid architecture

Wireless connectivity

– Over-the-air updates for MCU and FPGA through WiFi

Exchangeable light source

– Efficient LED driving, flexibility to change LEDs

Open hardware & software

K. Hewage, A. Varshney, A. Hilmia, T. Voigt

modBulb: A modular Light Bulb for VLC 4

SLIDE 5

Modular Design

Baseband Generator

– Modulated signal is digital

LED Driver - Constant current driving

– Non-linear IV characteristics

LED(s)

– Multiple LEDs – LEDs with different wavelengths

K. Hewage, A. Varshney, A. Hilmia, T. Voigt

modBulb: A modular Light Bulb for VLC 5

SLIDE 6

Baseband Generators: MCU & FPGA

MCU baseband generator CC3200 - ARM Cortex-M4 Core at 80 MHz Over-the-air updates through Wi-Fi Dedicated WiFi network processor Constrained by clock frequency Easy to program FPGA baseband generator Microsemi AGLN060 at 20 MHz (∼ 200 MHz) Over-the-air updates through MCU Parallel processing Precise control over the timing Complex to program

K. Hewage, A. Varshney, A. Hilmia, T. Voigt

modBulb: A modular Light Bulb for VLC 6

SLIDE 7

Modulation overhead

200 400 600 800 1000

Throughput (KBit/s)

5 10 15 20 25 30 35

Processing time (ms)

The modulation affects on the ability of performing additional processing.

K. Hewage, A. Varshney, A. Hilmia, T. Voigt

modBulb: A modular Light Bulb for VLC 7

SLIDE 8

Achievable Throughput

OOK FSK PPM

Modulation scheme

5 10 15 20

Throughput (MBit/s)

MCU FPGA

The FPGA based baseband generator allows higher throughput at the expense of ease of use.

K. Hewage, A. Varshney, A. Hilmia, T. Voigt

modBulb: A modular Light Bulb for VLC 8

SLIDE 9

LED Drivers: Linear Regulator & Switching Regulator

Linear regulator based driver Controls the current linearly High heat dissipation, inefficient Simple to prototype Bulky due to the attached heat sink Switching regulator based driver Controls the current by switching Very low heat dissipation, efficient Switching noise can appear in modulated light Widely used in commercial lighting

K. Hewage, A. Varshney, A. Hilmia, T. Voigt

modBulb: A modular Light Bulb for VLC 9

SLIDE 10

Noise comparison

Time (us) Linear Regulator 0.0 0.5 1.0 Signal (V) Time (us) Switching Regulator 0.0 0.5 1.0 Signal (V) 10 20 30 40 Time (us) Baseband Signal 5 Signal (V)

The switching regulator introduces noise at the benefit of power efficiency.

K. Hewage, A. Varshney, A. Hilmia, T. Voigt

modBulb: A modular Light Bulb for VLC 10

SLIDE 11

Efficiency of the Driver Circuits

LED driver LED current (A) Input power (W) Output power (W) Efficiency (%) Linear 0.566 6.79 3.47 51.10 Switching 0.508 3.48 3.04 87.36 The linear regulator based driver is less efficient than the switching regulator based driver circuit.

K. Hewage, A. Varshney, A. Hilmia, T. Voigt

modBulb: A modular Light Bulb for VLC 11

SLIDE 12

Multiple LEDs

1 2 3

Number of LEDs

200 400 600 800 1000 1200 1400

Light Intensity (Lux)

500 KBit/s OOK Without modulation

Since modBulb controls current, multiple LEDs can be added to increase the light intensity.

K. Hewage, A. Varshney, A. Hilmia, T. Voigt

modBulb: A modular Light Bulb for VLC 12

SLIDE 13

Sent & Received Waveforms

10 20 30 40 50 Time (us) 1 1 Signal

Sent Received

OOK modulation at 1 MBit/s

5 10 15 20 25 30 35 40 Time (us) 1 1 Signal

Sent Received

BFSK modulation at 500 KBit/s modBulb achieves a superior datarate than existing open embedded VLC hardware.

K. Hewage, A. Varshney, A. Hilmia, T. Voigt

modBulb: A modular Light Bulb for VLC 13

SLIDE 14

All Together

FPGA & MCU baseband generators, Switching LED driver

K. Hewage, A. Varshney, A. Hilmia, T. Voigt

modBulb: A modular Light Bulb for VLC 14

SLIDE 15

Conclusions & Future work

modBulb is an open tool to be used with embeded VLC Can be used beyond prototyping applications Future work

modBulb as a VLC receiver Analog modulations such as OFDM

modBulb will be truly open source

Schematics & PCBs Other design files

Visit our demo to see modBulb in action

K. Hewage, A. Varshney, A. Hilmia, T. Voigt

modBulb: A modular Light Bulb for VLC 15

SLIDE 16

Thank You

Thank You Q & A

K. Hewage, A. Varshney, A. Hilmia, T. Voigt

modBulb: A modular Light Bulb for VLC 16