Capacity bounds and concatenated codes over segmented deletion channels

Date
2013
Authors
Wang, F.
Duman, T. M.
Aktas, D.
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Supervisor
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Instructor
Source Title
IEEE Transactions on Communications
Print ISSN
0090-6778
Electronic ISSN
Publisher
IEEE
Volume
61
Issue
3
Pages
852 - 864
Language
English
Type
Article
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Abstract

We develop an information theoretic characterization and a practical coding approach for segmented deletion channels. Compared to channels with independent and identically distributed (i.i.d.) deletions, where each bit is independently deleted with an equal probability, the segmentation assumption imposes certain constraints, i.e., in a block of bits of a certain length, only a limited number of deletions are allowed to occur. This channel model has recently been proposed and motivated by the fact that for practical systems, when a deletion error occurs, it is more likely that the next one will not appear very soon. We first argue that such channels are information stable, hence their channel capacity exists. Then, we introduce several upper and lower bounds with two different methods in an attempt to understand the channel capacity behavior. The first scheme utilizes certain information provided to the transmitter and/or receiver while the second one explores the asymptotic behavior of the bounds when the average bit deletion rate is small. In the second part of the paper, we consider a practical channel coding approach over a segmented deletion channel. Specifically, we utilize outer LDPC codes concatenated with inner marker codes, and develop suitable channel detection algorithms for this scenario. Different maximum-a-posteriori (MAP) based channel synchronization algorithms operating at the bit and symbol levels are introduced, and specific LDPC code designs are explored. Simulation results clearly indicate the advantages of the proposed approach. In particular, for the entire range of deletion probabilities less than unity, our scheme offers a significantly larger transmission rate compared to the other existing solutions in the literature.

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Keywords
LDPC codes, MAP detection, Segmented deletion channel, Capacity bound, Deletion channels, LDPC codes, MAP detection, Marker codes, Synchronization error, Channel capacity, Signal encoding, Turbo codes, Concatenated codes
Citation
Published Version (Please cite this version)