Wearables Can Afford: Light-weight Indoor Positioning with Visible Light (Best Paper Candidate, Best Video Presentation Award)

  • Zeyu Wang
  • Zhice Yang
  • Jiansong Zhang
  • Chenyu Huang
  • Qian Zhang

ACM Mobisys 2015 |

Published by ACM Mobisys 2015

Best Paper Candidate, Best Video Presentation Award

Visible Light Positioning (VLP) provides a promising means to
achieve indoor localization with sub-meter accuracy. We observe
that the Visible Light Communication (VLC) methods in existing
VLP systems rely on intensity-based modulation, and thus they require
a high pulse rate to prevent flickering. However, the high
pulse rate adds an unnecessary and heavy burden to receiving devices.
To eliminate this burden, we propose the polarization-based
modulation, which is flicker-free, to enable a low pulse rate VLC.
In this way, we make VLP light-weight enough even for resourceconstrained
wearable devices, e.g. smart glasses. Moreover, the
polarization-based VLC can be applied to any illuminating light
sources, thereby eliminating the dependency on LED.
This paper presents the VLP system PIXEL, which realizes our
idea. In PIXEL, we develop three techniques, each of which addresses
a design challenge: 1) a novel color-based modulation scheme
to handle users’ mobility, 2) an adaptive downsampling algorithm
to tackle the uneven sampling problem of wearables’ low-cost camera
and 3) a computational optimization method for the positioning
algorithm to enable real-time processing. We implement PIXEL’s
hardware using commodity components and develop a software
program for both smartphone and Google glass. Our experiments
based on the prototype show that PIXEL can provide accurate realtime
VLP for wearables and smartphones with camera resolution
as coarse as 60 pixel 80 pixel and CPU frequency as low as
300MHz.