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SUMMARY:Coding problems involving values and their positions - Dr. Claudio
  Weidmann\, ENSEA\, France
DTSTART:20110421T103000Z
DTEND:20110421T113000Z
UID:TALK30988@talks.cam.ac.uk
CONTACT:Rachel Fogg
DESCRIPTION:Many signal processing and coding problems involve objects tha
 t can be represented as a vector of sparse nonzero values. Examples includ
 e image coding (compression)\, sampling of non-bandlimited processes with 
 finite rate of innovation\, compressed sensing (aka compressive sampling) 
 and error correction coding. Efficiency is gained through coding only the 
 nonzero values and their positions. The challenge lies in constructing non
 -adaptive sampling/coding schemes that need not know the positions of the 
 nonzero values\, but only their number.\n\nThis talk will focus on the exa
 mple of distributed source coding\, where a source is compressed assuming 
 that correlated side information is available at the decoder. Such systems
  fail if the correlation weakens intermittently. We present a general sche
 me that allows to "correct"\nsuch glitches and show how it can be implemen
 ted efficiently using LDPC codes. This illustrates that in certain cases\,
  location can be encoded very efficiently\, while in others\, no methods w
 ith practical decoding complexity are known.\n\n(Joint work with Francesca
  Bassi\, Michel Kieffer and Gottfried Lechner)\n
LOCATION:LR10\, Engineering\, Department of
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