University of Delaware - College of Engineering


Communication & Signal Processing

Turbo-like codes for distributed source and joint source-channel coding

Javier Garcia-Frias

Although turbo codes and low density parity check codes have been used very successfully in channel coding during the last decade, their application as source codes to perform data compression had not been considered. This is surprising, since the reason for their extraordinary performance as channel codes (i.e., their behavior as random-like codes that can be successfully decoded with reasonable complexity) would also predict extraordinary performance as source codes.

We have showed the possibility to perform data compression using turbo codes, extending the application of turbo-like codes to the important area of source coding. The proposed techniques achieve a performance very close to the theoretical limits. This occurs not just in the context of single sources, but also in the case of distributed coding of multi-terminal correlated sources, which is a much more complex problem. Of special interest is the case of transmission of correlated senders over multiple access channels, were we have developed a practical system capable of outperforming the Shannon separation principle. Although it is well know that in this case the separation between source and channel coding does not hold, no practical system had been able to surpass this bound. This research has important applications in the area of sensor networks, allowing the reduction of the energy consumption.

Recent publications

Y. Zhao, W. Zhong, and J. Garcia-Frias, "Transmission of Correlated Senders over a Rayleigh Fading Multiple Access Channel", To appear in Signal Processing.

J. Garcia-Frias and Y. Zhao, "Near Shannon/Slepian-Wolf Performance for Unknown Corrrelated Sources over AWGN Channels", IEEE Transactions on Communications, pp. 555-559, April 2005.

Y. Zhao and J. Garcia-Frias, "Joint Estimation and Compression of Correlated Non-Binary Sources Using Punctured Turbo Codes", IEEE Transactions on Communications, pp. 385-390, March 2005.

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