1. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
January 2016
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: Offset Variable Pulse Width Modulation for Smart Device Flash Light
Date Submitted: 10 January, 2016
Source: Jaesang Cha, Junghoon Lee, Seonhee Lee, Soo-Young Chang and Soonho Jung [SNUST]
Address : Seoul National University of Science & Technology [SNUST], Seoul, Korea
Voice: , FAX: ,
Re: Response to Call For IEEE r1 Proposal on November 2015
Abstract: Offset Variable Pulse Width Modulation for Smart Device Flash Light is proposed.
Purpose: Call for Proposal to IEEE r1 Optical Wireless Communication Response
Notice: This document has been prepared to assist the IEEE P It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P
Slide 1
Jaesang Cha, Seoul National Univ. of Science & Tech.
<author>, <company>

2. Contents Introduction
6/18/2018<month year>
January 2016
Contents
Introduction
App. based Smart Device Light(Flash, etc.) Control
Comparison App. based Flash Light control with HW Modem based Light control
Offset-VPWM
BER Performance
Conclusion
Jaesang Cha, Seoul National Univ. of Science&Tech

3. Introduction (1) Smart Device Light (Flash, etc.) based OWC
January 2016
Introduction (1)
Smart Device Light (Flash, etc.) based OWC
Another Device
Camera
Smart Device
Camera
Smart Device
(App based Tx )
Low Speed PD

4. January 2016
Introduction (2)
Low rate OWC (such as LED-ID and OCC) can be sent by Device Light and can be received by low rate PD or Camera.
Below picture is an example of Smart Devices.
- Left one shows low rate PD communication.
- Right one shows Camera communication.

5. January 2016
Introduction (3)
Proposed OWC/RF Hybrid mode can access High rate data from cloud by OWC address Pointer(URL, Address etc.)
Hybrid Tx : Smart device Light(Flash, etc.) & RF(3G/LTE, WiFi, Bluetooth etc.)
Hybrid Rx : Smart device Camera & RF(3G/LTE, WiFi, Bluetooth etc.)
Cloud Network
Connect by
Wi-Fi/BT
Smart Device Light + RF
Camera + RF
Link, URL,
IP Address, etc
- Smart Device Light’s data : OWC IP address Pointer (URL, Storage address etc.)
- RF data : High rate based access function to Virtual Cloud Big Data Network(Storages)
- Virtual Big data exchange(Flexible IoT solution) is available using Hybrid mode

6. Introduction (4) Authentication using Smart-Device Light and Camera
January 2016
Introduction (4)
Authentication using Smart-Device Light and Camera
LBS using Smart-Device Light(using Offset-VPWM) and Camera
LED Light
Smart Device
(LBS)
Gateway
(Camera)
Smart Device

7. App. based Smart Device Light Control(1)
January 2016
App. based Smart Device Light Control(1)
DLT
<SW structure of Smart Device >
<SW structure of Smart Device + Flash Light Tx App. >
Proposed scheme is App. based Device Light system without HW change
Just have only to add(install) “Device light transmitter(DLT)” App.

8. App. based Device Light Control(2)
January 2016
App. based Device Light Control(2)
App. (Application)
Device Light(Flash, etc.) control App.
: Light on/off control by calling framework IO
Main control block for Device light control
Frame Work
(Light IO IF) SW
Device Light IO interface
: Calling Devie Light driver
Kernel layer
(S/W Driver)
Flash Light IO interface
: On/Off Control of device
Flash device, etc. HW
Turn on or off light
App. is main control block for Device Light(Flash, etc.) control

9. January 2016
Comparison App. based Flash Light control with HW Modem based Light control(1)
HW modem based light control system can turn on/off light at absolutely exact time duration due to HW clock synchronization
App. based light control can’t keep turning on/off timing because it is performed by CPU

10. January 2016
Comparison App. based Flash Light control with HW Modem based Light control(2)
HW modem based
light control
App. based Flash
Exact time span
falling edge
rising edge
App. based Flash control can’t keep exact on/off timing when context switching process, ISR(interrupt service routine), and so on…
It can happen both rising and falling edge time

11. January 2016
Offset-VPWM (1)
In order to overcome Jitter problem, we propose new modulation scheme Offset-VPWM(Variable Pulse Width Modulation)
In Offset-VPWM, Data is expressed with offset pulse width
For example,
2bits data were mapped into 4 Offset-VPWM symbol as below
< Mapping Table>
Data bits
Pulse width 00 P 01
P+V 10
P+2V 11
P+3V
< Offset-VPWM scheme>

12. January 2016
Offset-VPWM (2)
Even though rising edge jitter happened, receiver can synchronize rising edge and check pulse width length

13. January 2016
Offset-VPWM (3)
If falling edge jitter happened, it can affect BER performance
For example,When sending ’00’,
If Tx signals falling edge happened with short pulse width(v)
then Rx’s decision making error is occurred (00  01) P
falling edge
0 0
00  01 v
0 1
Efficient offset value design is needed considering the relation falling jitter and pulse width

14. The number of simulation data
January 2016
BER Performance(1)
P is 40ms*
Falling edge is varied from 0%~5% of P
Offset length(v) is varied from 10~50% of P
<Simulation Parameters>
Item
Value
modulation
Offset-VPWM P
40ms
Falling edge jitter
0, 1, 2, 3, 4, 5% of P
PWM offset length(v)
10, 20, 30, 40, 50% of P
The number of simulation data
< Offset-VPWM scheme>
*P value 40ms is calculated via (1second) / (the number of flash blinking)
The number of blinking is the capacity how often mobile device can turn flash on and off means that the frequency which was tested using Nexus5S device.

15. BER Performance(2) January 2016 <Pulse offset length 10% of P>

16. 6/18/2018<month year>
January 2016
Conclusions
Offset Variable Pulse Width Modulation for Smart Device Light(Flash, etc.) are proposed
Proposed scheme is App. based Device Light system without HW change Just have only to add(install) “Device light transmitter(DLT)” App.
Offset-VPWM can be applied on LED-ID and OCC
Application scenarios like OWC/RF Hybrid method, Authentication, LBS were introduced
Smart Device based/connected Multiple Device Lights also can be applied
Jaesang Cha, Seoul National Univ. of Science&Tech.