Prof. Xiao Ma
Sun Yat-sen University, China
Date : 5 Feb 2026 (Thursday)
Time : 11:00 am – 12:00 nn
Venue : Rm 833, Ho Sin Hang Engineering Building, CUHK
Abstract:
In this talk, we make an attempt to integrate source coding, channel coding and joint source-channel coding (JSCC) into a single pair of encoder and decoder (with input length fixed but output length tunable according to the source entropy and the channel capacity). We introduce a special class of time-varying convolutional codes, called convolutional sampling and superposition (Conv-SaS) codes. We prove that, under blockwise maximum a posteriori (MAP) decoding, the Conv-SaS code ensemble achieves the limit of minimum transmission ratio (LMTR) when transmitting a Bernoulli source over memoryless binary-input output-symmetric (MBIOS) channels, also known as binary memoryless symmetric (BMS) channels, in terms of frame-error rate (FER). The main theorem is then adapted to the source coding, channel coding, JSCC, and (noiseless or noisy) Slepian-Wolf (SW) coding problems. In the simulations, the Conv-SaS code ensemble is expurgated as the convolutional repetition and superposition (Conv-RaS) code ensemble, a generalized block Markov superposition transmission (BMST) code ensemble. The construction of BMST codes is flexible with code rates (defined as the ratio of the output length to the input length) ranging from less than one (typically for source codes) to greater than one (typically for channel codes). More importantly, the BMST codes with moderately large sub-blocks can be decoded iteratively by a sliding window message passing algorithm, performing universally well for the JSCC and SW coding problems, as confirmed by simulations. Without complicated optimizations, the BMST codes can be implemented with a pair of encoder and decoder of essentially the same architecture but adjustable code rates.
Biography:
Xiao Ma received the Ph.D. degree in communication and information systems from Xidian University, China, in 2000. He is a Professor at the School of Computer Science and Engineering, Sun Yat-sen University, Guangzhou, China. From 2000 to 2002, he was a Post-Doctoral Fellow with Harvard University, Cambridge, MA, USA. From 2002 to 2004, he was a Research Fellow with the City University of Hong Kong. His research interests include information theory, channel coding theory and decoding algorithms.
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