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Development and Implementation of MIMO Optical Camera Communication Systems
Ph.D. Dissertation Defend
by Trang Nguyen
31th May 2018
Outlines
1 Introduction
A-QL system2
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Screen OFDM system
RoI Signaling
Selective-RoI high-rate OCC System
Annex 1 –Implemented Software Apps
Annex 3 –Screen OFDM details
Annex 2 –PHY configurations
Annex 4 –Channel measurement
Annex 5 –Technical Feasibility
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Additional Annexes: 01 – 10: Further Details of Implementation Aspects
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IntroductionGeneral description of the contents described in this thesis
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Screen
A-QL
Screen
OFDM
RoI-OCC
signaling
Hybrid
OCC
wavefor
m
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Screen-Camera OCC
This system
implements tri-color
band modulation for
a novel 2D-sequential
A-QL code design
RoI signaling waveform
This RoI signaling
waveform is designed for
delivering the short-ID of
multiple light sources to
conventional cameras.
Screen OFDM
This system
implements 2D-OFDM
for a quite-mature
screen code design
High-rate RoI signaling
This hybrid waveform is
to support cameras in
detection and tracking
multiple light sources
while staying connect at
high-rate with
interested ones.
Thesis Contents 4
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Classification of OCC
Screen
Nyquist sampling
Oversampling
by high frame rate
Region-of-Interest
Signaling
Rolling shutter
Nyquist sampling
Distance several meters < hundred meter hundreds of meter tens of meter
Data
ratekbps-Mbps kbps 10bps up to 22 kbps tens bps~ kbps
StandardIEEE 802.15.7m
PHY VI modesNot standardized
IEEE 802.15.7m
PHY IV modes
IEEE 802.15.7m
PHY V modes
Intended
Systems
• Screen Tx
• Typical cameras Rx
• Traffic light, LEDs-
array Tx
• High-speed camera
Rx
• Car light/traffic light/LED
Signage Tx
• RoI-camera Rx
• LED panel Tx
• Rolling shutter camera
Rx
Characteristics
• Massive spatial MIMO
• Short-range OWC
system utilizing
screen.
• Spatial MIMO
• Tx detection based
on image processing
is a drawback
• Hybrid waveform
• The RoI signaling stream
allows fast, reliable
detection and tracking of
multiple light sources
simultaneously.
• The trade-off between the
distance and the data
rate makes this the most
suitable option for indoor
application.
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MIMO System ≠ MIMO Block coding
A-QL 2D-OFDMRoI
SignalingHybrid
waveform
Massive cells for a short-range link
• implements a single luminaire that
composes of multiple (single-color band or
tri-color band) cells
• Data rate which relies much on the number
of cells can be achieved up to Mbps.
Massive cells available within Screen Tx.
• Applicable for point-to-point (P2P) short-
range communication within several
meters at which Rx can process the huge
amount of cells located in the two-dimensional plane.
Massive links in a challenging environment
• aims to support multiple multi-array-
luminaires those are spatially separated.
• Data rate for a single link relies much on the
frame rate of the camera, leaving the spatial
dimension free for other links connectivity.
Limited cells available within LED-Tx.
• Applicable for multiple points-to-multiple
points (MP2MP) long-range communication
(such as in a night scene/ vehicularenvironment).
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Highlights of Proposing Screen-Camera Systems
2D-OFDMA-QL
Code Area
Perspective Distortion
360o Rotation
Frame rate variation Rolling effect
Quite-mature design of MIMO
Tested performance
2D-carriers allocation Complete Features as A-QL
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Highlights of Proposing RoI-Signaling based OCC Systems
RoI Signaling
Hybrid waveform
S2-PSK
S2-PSK
Wide Applicability to Infrastructures
(LED-types and cameras)
Comparative Performance
Fuzzy decoder
▪ High speed with mobility support
▪ Design for efficient communication performance
▪ Good-dimming resolution and performance
▪ Applicable to either typical cameras/ RoI cameras
Multiple Tx
detection & tracking
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A-QL systemAsynchronous –Quick Link Screen-Camera System
Screen
A-QL
Short video demo – 16x16 A-QL 10
56 sec
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Short video demo – 32x32 A-QL 11
58 sec
Overall description
The A-QL system includes
• New 2D tri-color code design
• New bit mapper (bits to intensity)
• Channel encoder with particular encoding for asynchronous system
• Color calibration with estimation sequence
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Technical Contributions
Rotation support
Code Detection & Extraction
Simpler but more efficient than QR
code.
Sequential color-QR (tested)Rotation support in A-QL
Tested detection rate: > 20 fps
Linear estimation of cells
Efficient code extraction using
outer bolders.
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Technical Requirements
Technical Contributions
Asynchronous bits
Modulation and Coding
Temporal sampling correction Rolling effect removal
Preamble-PHR frame Data frame
Server two critical purposes:
▪ Temporal sampling correction
▪ Detect and Remove the rolling
effected images
PHY frame format
Header with channel estimation
Tri-color mapper
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Reliable Communication
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Technical Contributions
effective FEC
Implementation-ready
Outer
Reed SolomonInner Convolutional
Code
16×16 32×32 Diff. A-QL Hidden A-QL
Various versions of A-QL system are already implemented
Natural combination of FEC codes
▪ Inner CC
▪ Outer RR
Implementation shows BER <10-5
A-QL codes are implemented from
various adaptions.
▪ 16x16 and 32x32 A-QL
▪ Differential A-QL
▪ Hidden A-QL
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Implementation Aspect
Specifications
Design of A-QL code
▪ Outer bolder to support Rx in extracting the code
▪ Reference cells to support Rotation, Time-variant downsampling, Rolling effect cancellation
▪ Data cells to deliver bits through tri-color bands
Conceptual design of A-QL code
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Specifications
Pi +Pj +Pk ≠1
Color Shift Keying
Pi +Pj +Pk =1
Bits-to-Intensity mapping in A-QL
▪ Bit mapping rule: more freedom in the bit mapping in A-QL
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Specifications
Practical demo shows that the Walsh training
sequence is helpful for
▪ Color calibration
▪ Binary threshold
▪ Color calibration: resolved in the PPDU format
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Specifications
▪ PHY PIB attributes for APP-based flexible configuration of Tx and PPDU in A-QL
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Implementation
▪ Testing of A-QL code with BER < 10-5 at 3m distance (tested and verified by ETRI)
16×16 A-QL
32×32 A-QL
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Implementation
▪ Testing of mono-color differential A-QL code at 30m distance (tested and verified by Korea Testing Laboratory)
16×16 mono color A-QL
16×16 Differential A-QL
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Implementation
▪ Demo of 16x16 Hidden A-QL code (full screen mode) by imperceptibly modulating the screen intensity
16x16
16x16 embedding data
16x16 intensity modulation
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2D-OFDM screen-camera systemThis is intended for delivering 50kbps (implemented) or higher rate (implementable work) by employing 2-dimensional OFDM via Screen.
Screen
OFDM
Short video demo – Screen OFDM 24
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Overall description
The Screen OFDM system includes
• New design of multiple OFDM symbols within Tx as a MIMO approach
• All mature-features as A-QL has
• Complete creation procedures of OFDM symbols with experimental verification
• Detailed processing and decoding guidance
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Technical Contributions
MIMO Tx
Complete Features like A-QL
▪ Multi spatial-OFDM symbols
within Tx
▪ Multi subcarriers within symbol
Multiple symbols within Tx 2D-carriers Practical measurement of
channel attenuation
▪ Rotation support
▪ Fast code detection and extraction
▪ Perspective Distortion Correction
▪ Correction of temporal &Spatial
sampling error
-Temporal sampling error
-Spatial sampling error
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New design of Screen code
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Technical Contributions
Theoretically analyze the impacts of channel imperfection
Cosine-Fourth Law Blurry Image Impact Temporal and Spatial
sampling error
Nonlinear channel response Pixel Eb/No Clipping Noise
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Technical Contributions
Practically analyze the impacts of channel imperfection
On-focus condition Blurry condition
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