[Nets-seminars] Fwd: [nets] Nets seminar: Tuesday, 3 June at 2pm in MPEB 6.12

Mark Handley mark at handley.org.uk
Tue Jun 3 12:15:24 BST 2014

A reminder: Wenjun Hu's talk is at 2pm today.


----- Original message -----

From: Kyle Jamieson <[1]k.jamieson at cs.ucl.ac.uk>

To: [2]nets at cs.ucl.ac.uk

Subject: [nets] Nets seminar: Tuesday, 3 June at 2pm in MPEB 6.12

Date: Tue, 27 May 2014 19:32:29 +0100

Dear all, please join us this coming Tuesday 3 June in MPEB 6.12 for an
exciting seminar on visual light communication by Wenjun Hu from Yale.

Unsynchronized Visual Communication

As smartphone penetration continues to grow and displays are widely
available, there are many opportunities to transmit information over
screen-camera links in the form of a video of 2D barcodes. A key
challenge for smartphone based visual communication over screen-camera
links is imperfect frame synchronization. The difficulty arises from
frame rate diversity and variability due to camera capability, lighting
conditions, and system factors. If the transmit frame rate is too high,
the receiver might lose original frames or capture mixed frames, which
are normally not decodable. Previous systems simply reduce the
effective screen frame rate to be half the camera frame capture rate.
This under-utilizes the transmitter side capacity and is inefficient.

We achieve frame synchronization with LightSync, which features
in-frame color tracking to decode imperfect frames and a linear erasure
code across frames to recover lost frames. LightSync allows smooth
communication between the screen and the camera at any combination of
the transmit and receive frame rates, as long as the receive rate is at
least half the transmit rate. This means that each receiver can scale
the decoding performance with its own camera capability. Across several
phones, our system can more than double the average throughput compared
to previous approaches.


Wenjun Hu is an assistant professor of Electrical Engineering and
Computer Science at Yale University, based in the newly launched Yale
Institute for Network Science. Until the end of 2013, she was a
researcher at Microsoft Research Asia. Previously, she was a
postdoctoral research associate at the University of Washington. She
did her PhD with Prof. Jon Crowcroft at the University of Cambridge,
though spending about 7 months each at MIT CSAIL and Microsoft Research
Cambridge during her PhD. Her work has mainly focused on building
various wireless systems, including smartphone based visual
communication, wireless video, MIMO, and network coding in wireless
mesh networks.


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