Hybrid Visible Light Communication for Cameras and Low-Power Embedded Devices
Niranjini Rajagopal, Patrick Lazik, Anthony Rowe

Citation
Niranjini Rajagopal, Patrick Lazik, Anthony Rowe. "Hybrid Visible Light Communication for Cameras and Low-Power Embedded Devices". ACM Workshop on Visible Light Communication Systems in Conjunction with MobiCom, 7, September, 2014.

Abstract
Visible light communication (VLC) between LED light bulbs and smart-phone cameras has already begun to gain trac- tion for identification and indoor localization applications. To support detection by cameras, the frequencies and data rates are typically limited to below 1kHz and tens of bytes per second (Bps). In this paper, we present a technique for transmitting data from solid-state luminaries, used for inte- rior ambient lighting, simultaneously to both cameras and low-power embedded devices in a manner that is impercep- tible to occupants. This allows the camera communication VLC channel to also act as a higher speed downstream link and low-power wakeup mechanism for energy-constrained devices. Our approach uses Manchester encoding and Bi- nary Frequency Shift Keying (BFSK) to modulate the high- speed data stream and applies duty-cycle adjustment to gen- erate the slower camera communication signal. We explore the trade-off between the performance of the two communi- cation channels. Our hybrid communication protocol is also compatible with existing IR receivers. This allows lights to communicate with low-cost commodity chipsets and control home appliances such as TVs, AV receivers, AC window units, etc. We show that we are able to reliably simultane- ously transmit low-speed data at 1.3 Bps to camera enabled devices and higher-speed data at 104 Bps to low-power em- bedded devices. Since the majority of energy in many RF communication protocols often goes towards media access and receiving, VLC-triggered wakeup can significantly de- crease system energy consumption. We also demonstrate a proof-of-concept wakeup circuit that consumes less then 204uA and can be triggered in less then 10ms.

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Citation formats  
  • HTML
    Niranjini Rajagopal, Patrick Lazik, Anthony Rowe. <a
    href="http://www.terraswarm.org/pubs/345.html"
    >Hybrid Visible Light Communication for Cameras and
    Low-Power Embedded Devices</a>, ACM Workshop on
    Visible Light Communication Systems in Conjunction with
    MobiCom, 7, September, 2014.
  • Plain text
    Niranjini Rajagopal, Patrick Lazik, Anthony Rowe.
    "Hybrid Visible Light Communication for Cameras and
    Low-Power Embedded Devices". ACM Workshop on Visible
    Light Communication Systems in Conjunction with MobiCom, 7,
    September, 2014.
  • BibTeX
    @inproceedings{RajagopalLazikRowe14_HybridVisibleLightCommunicationForCamerasLowPowerEmbedded,
        author = {Niranjini Rajagopal and Patrick Lazik and Anthony
                  Rowe},
        title = {Hybrid Visible Light Communication for Cameras and
                  Low-Power Embedded Devices},
        booktitle = {ACM Workshop on Visible Light Communication
                  Systems in Conjunction with MobiCom},
        day = {7},
        month = {September},
        year = {2014},
        abstract = {Visible light communication (VLC) between LED
                  light bulbs and smart-phone cameras has already
                  begun to gain trac- tion for identification and
                  indoor localization applications. To support
                  detection by cameras, the frequencies and data
                  rates are typically limited to below 1kHz and tens
                  of bytes per second (Bps). In this paper, we
                  present a technique for transmitting data from
                  solid-state luminaries, used for inte- rior
                  ambient lighting, simultaneously to both cameras
                  and low-power embedded devices in a manner that is
                  impercep- tible to occupants. This allows the
                  camera communication VLC channel to also act as a
                  higher speed downstream link and low-power wakeup
                  mechanism for energy-constrained devices. Our
                  approach uses Manchester encoding and Bi- nary
                  Frequency Shift Keying (BFSK) to modulate the
                  high- speed data stream and applies duty-cycle
                  adjustment to gen- erate the slower camera
                  communication signal. We explore the trade-off
                  between the performance of the two communi- cation
                  channels. Our hybrid communication protocol is
                  also compatible with existing IR receivers. This
                  allows lights to communicate with low-cost
                  commodity chipsets and control home appliances
                  such as TVs, AV receivers, AC window units, etc.
                  We show that we are able to reliably simultane-
                  ously transmit low-speed data at 1.3 Bps to camera
                  enabled devices and higher-speed data at 104 Bps
                  to low-power em- bedded devices. Since the
                  majority of energy in many RF communication
                  protocols often goes towards media access and
                  receiving, VLC-triggered wakeup can significantly
                  de- crease system energy consumption. We also
                  demonstrate a proof-of-concept wakeup circuit that
                  consumes less then 204uA and can be triggered in
                  less then 10ms.},
        URL = {http://terraswarm.org/pubs/345.html}
    }
    

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