Vehicular Visible Light Communications

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Mobile and Vehicular Network Lab

Vehicular

Visible Light Communications

Hsin-Mu (Michael) Tsai (蔡欣穆)

Computer Science and Information Engineering National Taiwan University

2014 APEC Cooperative Forum on Internet of Vehicles

2014/5/20

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http://www.forcegt.com/wp-‐content/uploads/2012/09/volvo_road_train-‐11.jpg 2

IoV: Cooperation between Vehicles

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Building Roads: No Moore’s Law Here

Wugu-Yangmei Overpass (completed in 2013)   (for Freeway No. 1 in Taiwan)"

–  Cost: 3B USD for 40 km of elevated road 

- The most expensive (per unit length) in the history"

–  Divert approximately 25% of traffic from the original highway"

–  Improve rush hour average speed:  

- 40-50 kmph à 80-90 kmph"

http://twimg.edgesuite.net//images/twapple/640pix/20121217/LN06/LN06_004.jpg

3

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Increase Road and Energy Efficiency

•  At 100 km/h, the road surface utilization = 5%!

•  Reduce the gap - Longitudinal control  

" " " " "(adaptive cruise control) !

•  Reduce lane width - Automatic steering"

•  Reduce aerodynamic drag - Close-formation

automated platoons can save 10% to 20% of total energy use"

•  Only possible through cooperation with communications!

–  Drivers’ response delays cause stop and go disturbances"

45.5 m

5 m

3. 5 m 1.8 m

4

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5

Challenges: V2V Communications

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Challenge 1: Density and Speed

•  Range à reaction time"

•  200 km/h relative speed 

100 m = 1.8 s @ 200 km/h"

•  A 100-m road segment can have:"

– More than 600 scooters"

– More than 120 cars"

•  Heavy Interference"

•  The need for  

reliable communications"

6

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Challenge 2:

My loca(on is (X3, Y3) and my speed is 98 mph, and I am braking.

My loca(on is (X2, Y2) and my speed is 101 mph.

My loca(on is (X1, Y1) and my speed is 106 mph.

GPS Uncertainty = 5 -‐10 m

Who is Speaking?

Is the car in front of me braking?

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Challenge 3: Cost and Benefit

•  DSRC (IEEE 802.11p) – the current dominant standard for vehicular communications"

•  NOT in vehicle products today"

•  Low adoption incentive:  

where is the (day 1) benefit?!

– Minimum market penetration rate: 10% 

(All new cars have it à have to wait for 2 years)"

•  Low adoption incentive: high initial cost!

– Complexity similar to a WiFi radio"

– But with much lower quantity,  

when bootstrapping the market"

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9

Vehicular

Visible Light Communications

EE Times: Top 10 Automotive Agendas for 2014 & Beyond 7. Time to act on V2V,V2I

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Vehicular Visible Light Communications

10

1 0

1010

1 0 1 0

Time

Receiver Transmitter

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Keep the Light’s Original Function

11

Human eyes can’t perceive LED’s high frequency ﬂickering (persistence of vision)

Light

1 0 1 0

Time

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Receiver Options

Data Rate Number

of pixels Cost

Photodiode

module Up to  

several Mb/s 1 Extra

Camera

sensor A few Bytes/s Millions Use

existing cameras

Photodiode module Camera Sensor

Transmitter LED Lights

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Video: http://goo.gl/lo1f9 13

V2LC for Scooter Safety

S.-‐H. You, S.-‐H. Chang, H.-‐M. Lin, H.-‐M. Tsai, "Demo: Visible Light

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Your Car

Automatic Interference Filtering

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•  Visible light cannot penetrate obstacles = line-of-sight only"

•  VLC communication coverage = immediate neighbors only"

"à only those that could immediately collide with you!

•  Comparison: RF coverage includes a lot more irrelevant vehicles à additional interference à less reliable

RF Coverage

VLC Coverage

Automatic interference ﬁltering with VLC à Zero delay + zero overhead

à

**Always scalable to density & speed*!**

*S.-‐H. You, O. Shih, N. Wisitpongphan, H.-‐M. Tsai, and R. D. Roberts, “Smart Automotive Lighting for Vehicle

Challenge 1

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Highly Directional Transmission

Easily regulated output radiation pattern 

àHighly directional transmission with minimal leakage"

x location (m)

y location (m)

0 2 4 6 8 10

0 1 2 3 4 5 6

-120 -100 -80

Scooter Tail Light -60

Radiation Pattern

Tà

Safety regulation speciﬁes the minimum light intensity (at 30.48 m) within 20 degrees of irradiance angle.

W. Viriyasitavat, S.-‐H. Yu, and H.-‐M. Tsai, “Short Paper: Channel Model for Visible Light Communications using Oﬀ-‐the-‐shelf Scooter Taillight,” in Proc. IEEE Vehicular Networking

Challenge 1

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Simultaneous Transmissions

•  Lights occupy disjoint sets of pixels  

" " "(except when very far away: > 1km)"

•  Simultaneous transmissions  

"with no collision, interference, and access delay"

16

Challenge 1

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Talking Pixels

•  Computer vision:  

associate pixels with information (distance) and context"

•  V2LC: direct association - 

Information directly comes from the pixels!"

•  Photogrammetry: sub-meter accuracy for positioning"

www.ionroad.com

17

Challenge 2

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•  Low Cost: LED lights already used extensively for vehicles"

•  Extremely simple driver circuit: USD$2 microcontroller"

•  Aftermarket product is feasible:  

" "driver module and/or light module"

Low-Cost Transmitter:

Pervasive Existence of Automotive LED lights

Challenge 3

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Luxgen’s Eagle View+

360 degree vision coverage

•  Low cost: cameras already exist in many cars"

•  Aftermarket product is feasible: "

•  App download for mobile devices"

•  WiFi/Bluetooth link to light module"

" ₁₉

Challenge 3

Low-Cost Receiver:

Cameras Everywhere

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Conclusion

•  IoV creates new opportunities for both new

applications and huge performance improvements

•  New challenges need to be addressed:

–  Vehicle density and speed

–  Association of information and identity –  Market penetration

•  V2LC: new solution for vehicular communications

–  Reliable “point-‐to-‐point” V2V communications –  Direct association of information and pixels

–  Low-‐cost system design with aftermarket product options

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Thank you!

Please feel free to contact me for questions:

Prof. Hsin-‐Mu (Michael) Tsai (蔡欣穆)

hsinmu@csie.ntu.edu.tw

http://www.csie.ntu.edu.tw/~hsinmu/

Vehicular Visible Light Communications

Full text

Vehicular

Visible Light Communications

Hsin-Mu (Michael) Tsai (蔡欣穆)

Computer Science and Information Engineering National Taiwan University

2014 APEC Cooperative Forum on Internet of Vehicles

2014/5/20

IoV: Cooperation between Vehicles

Building Roads: No Moore’s Law Here

Wugu-Yangmei Overpass (completed in 2013) (for Freeway No. 1 in Taiwan)"

Increase Road and Energy Efficiency

• At 100 km/h, the road surface utilization = 5%!

• Reduce the gap - Longitudinal control

" " " " "(adaptive cruise control) !

• Reduce lane width - Automatic steering"

• Reduce aerodynamic drag - Close-formation

automated platoons can save 10% to 20% of total energy use"

• Only possible through cooperation with communications!

45.5 m

5 m

3. 5 m 1.8 m

Challenges: V2V Communications

Challenge 1: Density and Speed

• Range à reaction time"

• 200 km/h relative speed

100 m = 1.8 s @ 200 km/h"

• A 100-m road segment can have:"

– More than 600 scooters"

– More than 120 cars"

• Heavy Interference"

• The need for

reliable communications"

Challenge 2:

My loca(on is (X3, Y3) and my speed is 98 mph, and I am braking.

My loca(on is (X2, Y2) and my speed is 101 mph.

My loca(on is (X1, Y1) and my speed is 106 mph.

Who is Speaking?

Is the car in front of me braking?

Challenge 3: Cost and Benefit

• DSRC (IEEE 802.11p) – the current dominant standard for vehicular communications"

• NOT in vehicle products today"

• Low adoption incentive:

where is the (day 1) benefit?!

– Minimum market penetration rate: 10%

(All new cars have it à have to wait for 2 years)"

• Low adoption incentive: high initial cost!

– Complexity similar to a WiFi radio"

– But with much lower quantity,

when bootstrapping the market"

Vehicular

Visible Light Communications

Vehicular Visible Light Communications

1 0

1010

1 0 1 0

Time

Receiver Transmitter

Keep the Light’s Original Function

Human eyes can’t perceive LED’s high frequency ﬂickering (persistence of vision)

Light

1 0 1 0

Time

Receiver Options

V2LC for Scooter Safety

Automatic Interference Filtering

Always scalable to density & speed*!

Challenge 1

Highly Directional Transmission

Easily regulated output radiation pattern

àHighly directional transmission with minimal leakage"

Challenge 1

Simultaneous Transmissions

• Lights occupy disjoint sets of pixels

" " "(except when very far away: > 1km)"

• Simultaneous transmissions

"with no collision, interference, and access delay"

Challenge 1

Talking Pixels

Challenge 2

Wugu-Yangmei Overpass (completed in 2013)   (for Freeway No. 1 in Taiwan)"

•  At 100 km/h, the road surface utilization = 5%!

•  Reduce the gap - Longitudinal control  

•  Reduce lane width - Automatic steering"

•  Reduce aerodynamic drag - Close-formation

•  Only possible through cooperation with communications!

•  Range à reaction time"

•  200 km/h relative speed 

•  A 100-m road segment can have:"

– More than 600 scooters"

– More than 120 cars"

•  Heavy Interference"

•  The need for  

•  DSRC (IEEE 802.11p) – the current dominant standard for vehicular communications"

•  NOT in vehicle products today"

•  Low adoption incentive:  

– Minimum market penetration rate: 10% 

•  Low adoption incentive: high initial cost!

– Complexity similar to a WiFi radio"

– But with much lower quantity,  

**Always scalable to density & speed*!**

Easily regulated output radiation pattern 

•  Lights occupy disjoint sets of pixels  

•  Simultaneous transmissions  

•  IoV creates new opportunities for both new

•  New challenges need to be addressed:

–  Vehicle density and speed

–  Association of information and identity –  Market penetration

•  V2LC: new solution for vehicular communications

–  Reliable “point-‐to-‐point” V2V communications –  Direct association of information and pixels

–  Low-‐cost system design with aftermarket product options

目錄

第 4 卷第 1 期二〇一七年四月 VOL. 4 NO. 1 April 2017

第 7 卷第 2 期二〇二〇年十月 VOL. 7 NO. 2 October 2020

目錄

中華大學