一种低复杂度双二元卷积Turbo码译码算法

双二元卷积Turbo码（ DB CTC)的非二进制编码使得译码复杂度增加,限制了其在某些实际通信工程中的使用。在最大后验概率（ MAP)译码算法的基础上,提出了一种优化算法,将译码的存储量和计算量降为原来的1/4。仿真结果表明：在不同编码长度和码率的情况下,优化算法与原算法性能相当;在误码率为10-5的条件下,两者的Eb/N0差异同样不大于0.1 dB。     

Computerised search for linear binary codes

A computerised search procedure is described for finding new binary codes The method involves the extension of a given known code by annexing a number of parity-check digits to it in such a way that the minimum Hamming distance of the given code is improved. A number of codes found by this procedure have better rates than the best known codes of identical Hamming distance and the same number of information digits; a table of these codes is presented.     

Minimum-distance bounds for binary linear codes

This paper presents a table of upper and lower bounds ond_{max} (n,k), the maximum minimum distance over all binary, linear(n,k)error-correcting codes. The table is obtained by combining the best of the existing bounds ond_{max} (n,k)with the minimum distances of known codes and a variety of code-construction techniques.     

A class of high-speed decoders for linear cyclic binary codes

A general method is proposed for decoding any cyclic binary code at extremely high speed using only modulo2adders and threshold elements, and the decoders may be designed for maximum-likelihood decoding. The number of decoding cycles is a fraction of the number of digits in the code word.     

A method for extending binary linear codes (Corresp.)

Five binary linear[n, k, d]codes are presented that contain more words than the codes with corresponding values ofnanddthat are listed in the table of MacWilliams and Sloane. The construction method is a generalization of ConstructionXof Sioane, Reddy, and Chen.     

Error-correction capability of binary linear codes

The monotone structure of correctable and uncorrectable errors given by the complete decoding for a binary linear code is investigated. New bounds on the error-correction capability of linear codes beyond half the minimum distance are presented, both for the best codes and for arbitrary codes under some restrictions on their parameters. It is proved that some known codes of low rate are as good as the best codes in an asymptotic sense.     

The simplex codes and other even-weight binary linear codes for error correction

The probability of correct decoding on the binary-symmetric channel is studied. In particular, a class of codes with the same lengths and dimensions as the linear simplex codes, but with larger probability of correct decoding for all parameters p, 0 < p < 1/2, is given.     

On binary linear codes supporting t-designs

In this paper, we present classification results on self-orthogonal binary codes supporting designs, Therefore, we use special linear forms on the intersection numbers. In particular, one shows that a binary self-orthogonal code of distance d⩽18 whose set of minimal-weight codewords supports a 5-design has to be self-dual. We also prove that the codewords of any fixed weight in a [24m+22, 12m+11, 4m+6] Type I code support a 3-design     

Algebraic analog decoding of linear binary codes

Bit-by-bit soft-decision decoding of binary cyclic codes is considered. A significant reduction in decoder complexity can be achieved by requiring only that the decoder correct all analog error patterns which fall within a Euclidean sphere whose radius is equal to half the minimum Euclidean distance of the code. Such a "maximum-radius" scheme is asymptotically optimum for the additive white Gaussian noise (AWGN) channel. An iterative extension of the basic algebraic analog decoding scheme is discussed, and performance curves are given for the (17,9), (21,11), and (73,45) codes on the AWGN channel.     

New minimum distance bounds for certain binary linear codes

Let an [n, k, d]-code denote a binary linear code of length n, dimension k, and minimum distance at least d. Define d(n, k) as the maximum value of d for which there exists a binary linear [n, k, d]-code. T. Verhoeff (1989) has provided an updated table of bounds on d(n, k) for 1⩽k⩽n⩽127. The authors improve on some of the upper bounds given in that table by proving the nonexistence of codes with certain parameters     

A family of low-complexity blind equalizers

Two important topics in equalizer design are its complexity and its training. We present a family of blind equalizers which, by incorporating a decomposition finite-impulse response filtering technique, can reduce the complexity of the convolution operation therein by about one half. The prototype algorithm in this equalizer family employs the prevalent Godard cost function. Several simplified algorithms are proposed, including a sign algorithm which eliminates multiplications in coefficient adaptation and a few delayed versions. We also study the convergence properties of the algorithms. For the prototype algorithm, we show that, in the limit of an infinitely long equalizer and under mild conditions on signal constellations and channel characteristics, there are only two sets of local minima on the performance surface. One of the sets is undesirable and is characterized by a equalized channel response. The other corresponds to perfect equalization, which can be reached with proper equalizer initialization. For the simplified algorithms, corresponding cost functions may not exist. Some understanding of their convergence behaviors are obtained via examination of their adaptation equations. Simulation results are presented to demonstrate the performance of the algorithms.     

New binary linear codes from algebraic curves

Many new binary linear codes (compared with Brouwer's (2000) table) are found from a construction based on algebraic curves over finite fields     

An updated table of minimum-distance bounds for binary linear codes

In 1973 Helgert and Sfinaff published a table of upper and lower bounds on the maximum minimum-distance for binary linear error-correcting codes up to length127. This article presents an updated table incorporating numerous improvements that have appeared since then. To simplify the updating task the author has developed a computer program that systematically investigates the consequences of each improvement by applying several well-known general code-construction techniques. This program also made it possible to check the original table. Furthermore, it offers a quick and reliable update service for future improvements.     

On the Voronoi neighbor ratio for binary linear block codes

Soft-decision decoding of block codes is regarded as the geometrical problem of identifying the Voronoi region within which a given input vector lies. A measure, called the neighbor ratio, is proposed to characterize how many facets a Voronoi region has. Theory and algorithms are presented to determine the neighbor ratio for binary linear block codes and results are given for several types of codes. An asymptotic analysis for long codes reveals that the neighbor ratio depends on whether the code rate is less than 1/2 or not. For rates below this threshold, all pairs of codewords tend to share a Voronoi facet; for higher rates, a relatively small fraction of them do     

New family of binary one-step majority-logic decodable codes

One-step completely orthogonalisable binary codes derived from block designs are presented and their decoder structure is given.<>     

On applying molecular computation to binary linear codes

Adleman's (1994) successful solution of a seven-vertex instance of the NP-complete Hamiltonian directed path problem by a DNA algorithm initiated the field of biomolecular computing. In this correspondence, we describe DNA algorithms based on the sticker model to perform encoding, minimum-distance computation, and maximum-likelihood (ML) decoding of binary linear codes. We also discuss feasibility and limitations of the sticker algorithms     

Some new results on binary linear block codes

Certain properties of the parity-check matrix H of (n, k) linear codes are used to establish a computerised search procedure for new binary linear codes. Of the new error-correcting codes found by this procedure, two codes were capable of correcting up to two errors, three codes up to three errors, four codes up to four errors and one code up to five errors. Two meet the lower bound given by Helgert and Stinaff, and seven codes exceed it. In addition, one meets the upper bound. Of the even-Hamming-distance versions of these codes, eight meet the upper bound, and the remaining two exceed the lower bound.     

A low-complexity low-spurs digital architecture for wideband PLL applications

This paper presents a non-ideality analysis of the wideband frequency synthesizer, and proposes a new digital architecture for signal modulation and quantization. Using error masking strategy, this method can offer smaller routing area and less power consumption without sacrificing any system performance. Simulation results confirm the theoretical predictions. Finally, the design guidelines are derived to fulfill the customized synthesizer specifications.     

二元等距码的Q-变换分布及其应用

研究了二元等距码、等重等距码及其距离分布的Q-变换。通过使用Q-变换分布的性质,研究了二元等距码和等重等距码的最大码字数并得到2个新的上界,这些上界在某些情况下优于已知的结果。