List decoding

About: List decoding is a research topic. Over the lifetime, 7251 publications have been published within this topic receiving 151182 citations.

Parallel video decoding

Abstract: A video receiver/renderer is provided with a decoder equipped with hardware and/or software components adapted to decode at least two slices of a video in parallel, in part. In various embodiments, the decoder is constituted with multiple decoding units or decoding instructions that can be executed in multiple threads. A decoding unit/thread is advantageously equipped to determine whether a slice has decoding dependency, if so, whether the portion(s) of the video on which a slice's decoding is dependent has/have been decoded. If the result of the latter determination is negative, the decoding unit suspends itself until the determination result is affirmative. If the slice has no decoding dependency or the determination result is affirmative, the decoding unit proceeds to decode the slice.

Error Exponents of Expander Codes under Linear-Complexity Decoding

Abstract: A class of codes is said to reach capacity {\scriptsize $C$} of the binary symmetric channel if for any rate $R 0$ there is a sufficiently large N such that codes of length $\ge N$ and rate R from this class provide error probability of decoding at most $\varepsilon$, under some decoding algorithm. The study of the error probability of expander codes was initiated by Barg and Z{emor in 2002 [IEEE Trans. Inform. Theory, 48 (2002), pp. 1725--1729], where it was shown that they attain capacity of the binary symmetric channel under a linear-time iterative decoding with error probability falling exponentially with code length N. In this work we study variations on the expander code construction and focus on the most important region of code rates, close to the channel capacity. For this region we estimate the decrease rate (the error exponent) of the error probability of decoding for randomized ensembles of codes. The resulting estimate gives a substantial improvement of previous results for expander codes and some other explicit code families.

The Minimum Decoding Delay of Maximum Rate Complex Orthogonal Space–Time Block Codes

Abstract: The growing demand for efficient wireless transmissions over fading channels motivated the development of space-time block codes. Space-time block codes built from generalized complex orthogonal designs are particularly attractive because the orthogonality permits a simple decoupled maximum-likelihood decoding algorithm while achieving full transmit diversity. The two main research problems for these complex orthogonal space-time block codes (COSTBCs) have been to determine for any number of antennas the maximum rate and the minimum decoding delay for a maximum rate code. The maximum rate for COSTBCs was determined by Liang in 2003. This paper addresses the second fundamental problem by providing a tight lower bound on the decoding delay for maximum rate codes. It is shown that for a maximum rate COSTBC for 2m - 1 or 2m antennas, a tight lower bound on decoding delay is r = (m-1 2m) . This lower bound on decoding delay is achievable when the number of antennas is congruent to 0, 1, or 3 modulo 4. This paper also derives a tight lower bound on the number of variables required to construct a maximum rate COSTBC for any given number of antennas. Furthermore, it is shown that if a maximum rate COSTBC has a decoding delay of r where r < r les 2r, then r=2r. This is used to provide evidence that when the number of antennas is congruent to 2 modulo 4, the best achievable decoding delay is 2(m-1 2m_).

On the Waterfall Performance of Finite-Length SC-LDPC Codes Constructed From Protographs

Abstract: An analysis of spatially coupled low-density parity-check (SC-LDPC) codes constructed from protographs is proposed. Given the protograph used to generate the SC-LDPC code ensemble, a set of scaling parameters to characterize the average finite-length performance in the waterfall region is computed. The error performance of structured SC-LDPC code ensembles is shown to follow a scaling law similar to that of unstructured randomly constructed SC-LDPC codes. Under a finite-length perspective, some of the most relevant SC-LDPC protograph structures proposed to date are compared. The analysis reveals significant differences in their finite-length scaling behavior, which is corroborated by simulation. Spatially coupled repeat-accumulate codes present excellent finite-length performance, as they outperform in the waterfall region SC-LDPC codes of the same rate and better asymptotic thresholds.

On the implementation of minimum-redundancy prefix codes

Abstract: Minimum-redundancy coding (also known as Huffman (1952) coding) is one of the enduring techniques of data compression. We examine how best minimum-redundancy coding can be implemented, with particular emphasis on the situation when n is large, perhaps of the order of 10/sup 6/. We review techniques for devising minimum-redundancy codes, and consider in detail how encoding and decoding should be accomplished. In particular, we describe a modified decoding method that allows improved decoding throughput, requiring just a few machine operations per output symbol (rather than for each decoded bit), and uses just a few hundred bytes of memory above and beyond the space required to store an enumeration of the source alphabet. We review methods for calculating codeword lengths, show how those codeword lengths should be used to derive a minimum-redundancy code that has the alphabetic sequence property, and describes a memory-compact method for decoding such canonical codes. An improved method for decoding canonical codes is also presented.