Conference Paper

# Protograph-Based LDPC Convolutional Codes for Correlated Erasure Channels

Univ. of California San Diego, La Jolla, CA, USA

DOI: 10.1109/ICC.2010.5502364 Conference: Communications (ICC), 2010 IEEE International Conference on Source: IEEE Xplore

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**ABSTRACT:**Low implementation complexity, low delay and close-to-optimal performance over a wide variety of channels are some of the advantages of spatially-coupled low-density parity-check (LDPC) codes. However, the error performance of the sliding window decoding scheme that is used to decode these codes is considerably degraded over channels with memory, such as the correlated erasure channel. Employing a block interleaver to encounter this situation is not always a viable option, since it introduces a large amount of delay and cancels out the low-delay property of the sliding window decoder. Another way to reduce the effects of erasure bursts is to construct a more robust code ensemble by presenting additional code design rules. However, this approach results in additional constraints on the already complicated code construction process. The authors propose a novel communication system that combats the effects of the erasure bursts through the use of a convolutional interleaver. The proposed system combines the inherent convolutional nature of the spatially-coupled LDPC codes with that of a convolutional interleaver to achieve very low overall delay. The performance of the proposed approach is analysed using the density evolution technique and the performance improvement is demonstrated as a function of the interleaving delay via computer simulations.IET Communications 01/2013; 7(8):755-765. · 0.72 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**Spatially coupled codes have been of interest recently owing to their superior performance over memoryless binary-input channels. The performance is good both asymptotically, since the belief propagation thresholds approach the Shannon limit, as well as for finite lengths, since degree-2 variable nodes that result in high error floors can be completely avoided. However, to realize the promised good performance, one needs large blocklengths. This in turn implies a large latency and decoding complexity. For the memoryless binary erasure channel, we consider the decoding of spatially coupled codes through a windowed decoder that aims to retain many of the attractive features of belief propagation, while trying to reduce complexity further. We characterize the performance of this scheme by defining thresholds on channel erasure rates that guarantee a target erasure rate. We give analytical lower bounds on these thresholds and show that the performance approaches that of belief propagation exponentially fast in the window size. We give numerical results including the thresholds computed using density evolution and the erasure rate curves for finite-length spatially coupled codes.IEEE Transactions on Information Theory 01/2013; 59(4):2277-2292. · 2.62 Impact Factor -
##### Conference Paper: Performance analysis of spatially coupled codes over the correlated erasure channel

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**ABSTRACT:**Desirable characteristics of spatially-coupled low-density parity-check (LDPC) codes including low implementation complexity, low-delay, and close-to-optimal performance over a wide variety of channels make them a noticeable candidate for the next-generation wireless communication standards. However, error performance of the sliding window decoding scheme used to decode these codes is considerably degraded over channels with memory, such as the burst erasure channel. Traditionally, communication over channels with memory is achieved through the use of block interleavers but as it introduces a large amount of delay, it is not always a viable option. In this paper, employing a convolutional interleaver which benefits from the inherent convolutional nature of the spatially-coupled codes with very low overall delay is considered. The performance of the proposed combination is analyzed using the density evolution technique. The performance improvement of using a convolutional inter-leaver is demonstrated as a function of the added interleaving delay in terms of iterative decoding thresholds.Signal Processing and Communications Applications Conference (SIU), 2013 21st; 01/2013

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