Download - IEEE Mentor

July 2009
doc.: IEEE 802.15-09-0557-01
Project: IEEE P802.15 Working Group for Wireless Personal Area
Networks (WPANs)
Submission Title: VLC Coexistence with Lighting Control
Date Submitted: July 15, 2009
Source: Soo-Young Chang, CSUS, Myunghee Son, Jong-Hyun Park, and Sung Won
Sohn, ETRI
E-Mail: [email protected], [email protected]
Re:
Some technical system structures on VLC
Abstract: To discuss and solve a problem incurred by outside light control drives of
existing lighting systems, some thoughts are addressed and some relevant system
structures are introduced.
Purpose: To Introduce some technical issues on visible light communications
Notice: This document has been prepared to assist the IEEE P802.15. 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 P802.15.
Submission
Slide 1
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
VLC COEXISTENCE
WITH LIGHTING CONTROL
July 2009
Soo-Young Chang, CSUS,
Myunghee Son,
Jong-Hyun Park, and Sung Won Sohn, ETRI
Submission
Slide 2
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
INTRODUCTION
•
Rick Roberts et al. questioned about hardware
partitioning of the PHY layer into two parts communication part and light control part - in
IEEE802.15-09-0204-00-0007, Mar. 2009
–
to allow most of on-the-shelf LED control modules provided by
LED manufacturers to be used for VLC without modification
to ease LED manufacturers’ burden to facilitate interface to
communication part.
–
•
In this document a few structures by which splitting
PHY is not needed to make communication features
be independent of outside lighting control.
Submission
Slide 3
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
HARDWARE PARTITIONING QUESTIONED
BY RICK ROBERTS ET AL. [1]
Hardware partitioning against the protocol stack for LED infrastructure
lighting
The standard specifies the air
interface at the transmission source.
This includes the LED light source.
PHY Layer
The PHY layer is split between the upper PHY (FEC, etc.) - which is supplied by
the VLC vendor – and the lower PHY which is the LED light panel, which may
NOT be supplied by the VLC vendor.
Submission
Slide 4
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
POSSIBLE PHY PARTITIONING AND
COMMENTS ON IT (1)
PHY partitioning suggested in [1]
• The PHY layer is split between
the upper PHY (FEC, etc.), which is supplied by the VLC vendor, and
the lower PHY (LED light panel), which may NOT be supplied by the
VLC vendor.
Comments
 Basic assumption: the “LED light panel” may not recognize the
existence of VLC and may not be affected by VLC.  more desirable
 Without splitting into two PHYs, it is more desirable for VLC to have only
two traditional layers – MAC and PHY.
 The VLC can have simple control/input to the LED light panel for
communications. This simple control/input should be able to be applied
to any LED systems through which VLC can be achieved.
 The requirements for these LED systems (or any other lighting systems)
for VLC should be minimal to allow more LEDs (or other light sources)
available to be used with no or simple modifications.
Submission
Slide 5
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
POSSIBLE PHY PARTITIONING AND
COMMENTS ON IT (2)
The splitting of the PHY layer proposes a potential problem for the
infrastructure VLC model: [1]
•
Existing LED lighting will have to be retrofitted to support VLC.
 This problem can be solved by simplifying control so as not to affect lighting
control format for lighting systems by VLC control/processing.
•
Ideally, new LED lighting would be manufactured with an VLC interface in
place.
 This VLC interface features should be minimized to minimize burden for VLC
to LED industries.
•
So what assumptions should 802.15.7 make about the light panel interface?
What kind of “modulation” will be supported at the light panel? OOK?
PWM? OFDM? At what data rate? What about dimmers?
 Through 15.7 proposal procedure, the best technology including modulation
scheme(s) should be identified and adopted so that this interface can be
simplified and minimized while lighting performance is not degraded.
•
What we need is a functional interface specification to the light panel. But
how do we get that?
 By defining a set of specifications so as not to affect lighting control while
performing communications, this can definitely be achieved.
Submission
Slide 6
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
POSSIBLE PHY PARTITIONING AND
COMMENTS ON IT (3)
It could be a two part process for infrastructure lighting … [1]
• Part 1: specification of MAC and Upper PHY by 802.15.7
• Part 2: specification of the Lower PHY interface by ????
 PHY does not need to be split and both of the above two parts
should be specified by 802.15.7.
 Even the air interface which can be a part of lighting control such as
in forms of voltage or current control can be specified while lighting
control does not recognize this communication function.
LED lighting that is installed without a VLC interface will require TBD
modifications to accommodate VLC. And LED lighting lasts a long
time. It could be years before the next generation of LED lighting is
installed due to product churn. [1]
 It is more desirable that existing lighting systems can be utilized with
no or minimal modification or addition to them for VLC.
Rick Roberts recommended the group to look at a document on LM3445 “Triac Dimmable
Offline LED Driver” [2] to get some help to clarify some issues he suggested in [1].
Submission
Slide 7
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
SOME THOUGHTS ON THIS ISSUE
•
It totally depends on what technologies will be used for
the 15.7 standard.
– Including modulation techniques
– What happens if modulation technique applied is not dependent
on technical characteristics of LED deployed?
– What problem if only simple current or voltage control is needed
to the LED control panel for VLC? This control can be
implemented even for existing LED lighting systems already
deployed.
•
Basically it is more desirable that the standard for VLC
be independent of lighting systems.
– The VLC should be coexistent with or adapted to any
(infrastructure) lighting systems. To do this, simple inputs are
allowed to be inputted to the lighting controller.
Submission
Slide 8
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
VLC SYSTEM STRUCTURE WITH PHY
PARTITIONING
Case that the light control module is a part of PHY of VLC (a typical case) [1]
The standard specifies the air
interface at the transmission source.
This includes the LED light source.
PHY Layer
With this structure there is a problem to specify the 15.7 standard for VLC
because of uncertainty of lighting system specifications applied: to overcome
this problem, four structures are being proposed in the following slides.
Submission
Slide 9
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
PROPOSED VLC SYSTEM STRUCTURE 1
Structure 1-1: with light control performed through VLC higher layers :
control through VLC
Covered by 802.15.7 standard
Light control input from outside
Lighting system is not a part of VLC: a stand-alone lighting system already deployed.
Submission
Slide 10
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
PROPOSED VLC SYSTEM STRUCTURE 1
Structure 1-2: with light control performed through VLC higher layers :
control through VLC with light abstraction layer (LAL)
Covered by 802.15.7 standard
Light control input from outside
Lighting system is not a part of VLC: a stand-alone lighting system already deployed.
Submission
Slide 11
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
PROPOSED VLC SYSTEM STRUCTURE 2
Structure 2-1: with light control performed through VLC MAC layer :
control through VLC
Covered by 802.15.7 standard
Light control input from outside
Lighting system is not a part of VLC: a stand-alone lighting system already deployed.
Submission
Slide 12
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
PROPOSED VLC SYSTEM STRUCTURE 2
Structure 2-2: with light control performed through VLC MAC layer :
control through VLC with light abstraction layer (LAL)
Covered by 802.15.7 standard
Light control input from outside
Lighting system is not a part of VLC: a stand-alone lighting system already deployed.
Submission
Slide 13
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
PROPOSED VLC SYSTEM STRUCTURE 3
Structure 3-1: with separate outside light control: input from VLC to light
drive only for comm.
Digital or analog control
Light control input from outside
Covered by 802.15.7 standard
Lighting system is not a part of VLC: a stand-alone lighting system already
deployed with digital or analog control.
Submission
Slide 14
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
PROPOSED VLC SYSTEM STRUCTURE 3
Structure 3-2: with separate outside light control: input from VLC to light
drive only for comm. with light abstraction layer (LAL)
Digital or analog control
Light control input from outside
Covered by 802.15.7 standard
Lighting system is not a part of VLC: a stand-alone lighting system already
deployed with digital or analog control.
Submission
Slide 15
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
PROPOSED VLC SYSTEM STRUCTURE 4
Structure 4-1: with separate outside light control and lighting/VLC
interface : only input from VLC to interface module for comm.
Light control input
from outside
Digital or analog control
Covered by 802.15.7 standard
Lighting system is not a part of VLC: a stand-alone lighting system already
deployed with control.
Submission
Slide 16
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
PROPOSED VLC SYSTEM STRUCTURE 4
Structure 4-2: with separate outside light control inputted to light abstraction
layer: only input from VLC to light abstraction layer (LAL) for comm.
Light control input
from outside
Digital or analog control
Covered by 802.15.7 standard
Lighting system is not a part of VLC: a stand-alone lighting system already
deployed with control.
Submission
Slide 17
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
FUNCTIONS OF EACH LEVEL OF LAYERS
- MAC level control for PHY and VLC communications
- Communication with next higher layer
- Lighting control (optional)
- Simple LED input to deliver information transmitted
- Facilitate modulation of light signals
- Reception of signal information from photo detectors
- Lighting control (optional)
- Communication with MAC
- Less PHY overhead incurred by lighting
- Easy to combine signals from VLC and lighting
- Provide power to drive LEDs
- Brightness control if needed
- Flexible selection of light sensors as PD, IS, etc
-Emission of light controlled by light drive
-Detecting of light controlled by light sensor
Submission
Slide 18
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
POINTS TO BE CONSIDERED FOR
PROPOSALS (1)
•
•
•
More efforts should be made not to split PHY into two
parts and avoid major modification of lighting control
panel (or simply lighting panel).
The standard will define MAC and PHY as shown in
Structures 1, 2, 3, and 4.
The future proposals/contributions will include
technical methodology to implement these structures
suggested here.
– More considerations should be given to the
proposed technologies which facilitate the
suggestions so far mentioned. Or more desirably
the proposals should facilitate them to avoid
unnecessary need to modify the light control
modules for VLC.
Submission
Slide 19
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
POINTS TO BE CONSIDERED FOR
PROPOSALS (2)
•
For example, if LM3445 is used [2], one of some of the following
pins can be used to manipulate light signals to convey information
depending on modulation scheme adopted by the future standard:
–
–
–
Pin 1 ASNS PWM output of the triac dim decoder circuit
Pin 2 FLTR1 First filter input.
Pin 3 DIM Input/output dual function dim pin. This pin can be driven
with an external PWM signal to dim the LEDs.
Pin 4 COFF OFF time setting pin.
Pin 5 FLTR2 Second filter input.
–
–
•
It totally depends on what parameters will be used for signal
processing (or signal manipulation for information delivery):
–
–
–
–
Submission
Varying currents
Varying voltages
Varying colors (or wavelengths)
Or any other parameters which can be processed with the existing
and future lighting systems
Slide 20
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
POINTS TO BE CONSIDERED FOR
PROPOSALS (3)
•
The minimum requirements to accommodate existing
and future lighting drive systems and lighting devices
including LEDs should be identified and included in
TCD.
–
To do this, study on lighting drive devices and systems should
be performed and common control schemes should be
identified.
These common control schemes can be used for VLC light
signal processing.
–
•
Recommendation to the group
–
Submission
To include a statement in ” Coexistence with ambient light
and other lighting systems” of the TCD [3] to inform the
proposers of the need of these requirements.
Slide 21
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
OBSERVATIONS/CONCLUSIONS
•
These concepts can be applied for any light sources
as well as LEDs.
–
•
The concepts can be generalized to be applied for any light
sources.
Adaptive data rates should be achieved through these
concepts due to the specifications of light sources
used.
–
Submission
Achievable data rates (or the amount of information delivered)
depend on the type of light sources and their radiant powers –
especially when applying brightness (or dimming) control.
Slide 22
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI
July 2009
doc.: IEEE 802.15-09-0557-01
REFERENCES
1.
2.
3.
Rick Roberts, Intel Corp. and Tom Matsumura, VLCC, A standardized
LED infrastructure lighting interface, IEEE802.15-09-0204-00-0007, Mar.
2009
LM3445 Triac Dimmable Offline LED Driver, National Semiconductors,
http://www.national.com/ds/LM/LM3445.pdf, Mar. 2009
Sridhar Rajagopal, Samsung Electronics (Editor), TG7 Technical
Considerations Document (TCD) , IEEE802.15-09-0115-07-0007, July
2009
Submission
Slide 23
S.-Y. Chang, CSUS, Myunghee Son, et al., ETRI