Variable-Length Codes for Joint Source-Channel Coding
- When?
- Thursday 30 June 2011, 14:00 to 15:00
- Where?
- 39BB02
- Open to:
- Staff, Students
- Speaker:
- Dr Victor Buttigieg
Since the introduction of Huffman codes back in 1952, variable-length codes have been used in several data compression standards, including the latest video coding standards such as H.264, usually as part of their entropy coding sub-systems. Although not as good as other data compression schemes, such as for example Arithmetic Coding, they still prove popular in practical implementations due to their simplicity. However, from early on it was realized that variable-length codes suffer from error-propagation under noisy conditions. Several techniques have been proposed to mitigate this behaviour, including the use of synchronisation codewords, self-synchronising codes and reversible variable-length codes.
. In 1993 the author introduced a new class of variable-length error-correcting (VLEC) codes. These codes not only limit the effect of errors, but are also capable to correct errors. A trellis description for these codes was introduced and a maximum likelihood decoding algorithm given. Other authors later extended this work by giving a maximum a-posteriori decoding algorithm which can also be used in iterative decoding of VLEC codes concatenated with other more powerful standard error-correcting codes. This presentation will give an overview of variable-length codes under noisy conditions, including the recently introduced codes that are able to correct not just substitution errors, but also deletion and insertion errors.
Dr Ing Victor Buttigieg joined the University of Malta in 1990 as an Assistant Lecturer. In 1991 he was awarded a Commonwealth Academic Staff Scholarship by the Association of Commonwealth Universities. Following research work in the area of combined source and channel coding, he was awarded a Ph.D. degree by the University of Manchester, UK, in 1995. Soon thereafter, Dr Buttigieg joined the newly formed Department of Communications and Computer Engineering at the University of Malta where he is currently a Senior Lecturer. He also served as Head of Department in the period 2004-08 and Deputy Dean of the newly constituted Faculty of Information and Communication Technology in the period 2007-09. Victor Buttigieg lectures in the fields of Digital Signal Processing, Telecommunications and Coding Theory. His main research interests are in source and channel coding and multimedia indexing. He was directly responsible for projects worth in total more than 1.3 million euro. He was also the founding President of the University of Malta Academic Staff Association (UMASA), which he led from 2001-09. During this period he was chief negotiator in the negotiations leading to the new Collective Agreement covering the working conditions of academic staff at the University of Malta.