一种快速有效的自适应算术编码

介绍了算术编码的原理和基于模型的自适应算术编码算法,并利用二进制索引树这样一个高效率的数据结构对传统的0阶自适应算术编码进行了改进。实验表明,无论对于高度集中的数据集还是对于分布较为均匀的数据集,在运行时间上新算法都有较大的改进。     

确定周期为P n的二元序列k-错复杂度曲线的快速算法

设计了一个确定周期为P^n的二元序列k-错复杂度曲线的算法,这里p为素数,并且2是模P^2的一个本原根。该算法分别推广了魏-白-肖和魏-董-肖计算二元P^n周期序列线性复杂度与k-错复杂度的算法。     

A fast algorithm for the performance index of a telecommunicationnetwork

A performance index for a telecommunication network is defined as a composite index integrating the important measures of both reliability and capacity. In this index the network states that permit a flow capability less than the maximum, are not totally ignored but are assigned a normalized weight less than one. A fast method is proposed for deriving the symbolic expression of the performance index in a compact form. Because the capacity of several subnetworks must be computed, an efficient procedure for capacity determination is also suggested. An example illustrates the procedure and points out the simplicity of the resulting expression for the performance index     

A fast algorithm for reduced complexity sequence estimationachieving the optimum error exponent

A reduced complexity sequence estimator is presented which discards certain trellis paths based on their path metric and the minimum Euclidean distance in the trellis. An upper bound for the average number of retained paths is derived and the receiver is shown to achieve the optimum error exponent of the maximum likelihood sequence estimator. A fast implementation is proposed and simulation results are presented     

一种快速有效的帧级码率控制算法

基于对码率控制算法的研究，取H．263 的TMN8码率控制算法和DivX的平均码率控制算法之长，提出了一种新型帧级码率控制算法，给出了实现算法的步骤和软件流程，实验表明该码率控制算法快速、简便、有效，并可将它应用于视频监控系统中。     

A fast algorithm for determining the complexity of a binary sequence with period2^n(Corresp.)

The complexity of a periodic sequence(s)is defined to be the least number of stages in a linear feedback shift register that generates(s).     

A recursive least M-estimate algorithm for robust adaptive filtering in impulsive noise: fast algorithm and convergence performance analysis

This paper studies the problem of robust adaptive filtering in impulsive noise environment using a recursive least M-estimate algorithm (RLM). The RLM algorithm minimizes a robust M-estimator-based cost function instead of the conventional mean square error function (MSE). Previous work has showed that the RLM algorithm offers improved robustness to impulses over conventional recursive least squares (RLS) algorithm. In this paper, the mean and mean square convergence behaviors of the RLM algorithm under the contaminated Gaussian impulsive noise model is analyzed. A lattice structure-based fast RLM algorithm, called the Huber Prior Error Feedback-Least Squares Lattice (H-PEF-LSL) algorithm is derived. Part of the H-PEF-LSL algorithm was presented in ICASSP 2001. It has an order O(N) arithmetic complexity, where N is the length of the adaptive filter, and can be viewed as a fast implementation of the RLM algorithm based on the modified Huber M-estimate function and the conventional PEF-LSL adaptive filtering algorithm. Simulation results show that the transversal RLM and the H-PEF-LSL algorithms have better performance than the conventional RLS and other RLS-like robust adaptive algorithms tested when the desired and input signals are corrupted by impulsive noise. Furthermore, the theoretical and simulation results on the convergence behaviors agree very well with each other.     

Error performance of preamplified optical PPM systems with finite extinction ratios

In this paper, we present an analytical study of the error performance in optically preamplified, M-ary pulse position modulation, in free-space optical communication systems with finite extinction ratios. We derive a theoretical expression for the probability of bit error and compute it numerically for different symbol sizes and extinction ratios. We also provide the power penalty due to a finite extinction ratio for both coded and uncoded systems. The study shows that, in certain cases and for a given extinction ratio, lower symbol sizes may yield an error performance similar to that achieved by higher symbol sizes.     

Product accumulate codes: a class of codes with near-capacity performance and low decoding complexity

We propose a novel class of provably good codes which are a serial concatenation of a single-parity-check (SPC)-based product code, an interleaver, and a rate-1 recursive convolutional code. The proposed codes, termed product accumulate (PA) codes, are linear time encodable and linear time decodable. We show that the product code by itself does not have a positive threshold, but a PA code can provide arbitrarily low bit-error rate (BER) under both maximum-likelihood (ML) decoding and iterative decoding. Two message-passing decoding algorithms are proposed and it is shown that a particular update schedule for these message-passing algorithms is equivalent to conventional turbo decoding of the serial concatenated code, but with significantly lower complexity. Tight upper bounds on the ML performance using Divsalar's (1999) simple bound and thresholds under density evolution (DE) show that these codes are capable of performance within a few tenths of a decibel away from the Shannon limit. Simulation results confirm these claims and show that these codes provide performance similar to turbo codes but with significantly less decoding complexity and with a lower error floor. Hence, we propose PA codes as a class of prospective codes with good performance, low decoding complexity, regular structure, and flexible rate adaptivity for all rates above 1/2.     

EFBLA: a two-phase matching algorithm for fast motion estimation

A novel motion estimation algorithm that contains edge matching and block matching is presented. The edge matching reduces candidates for the block matching that performs accurate searching. Thus, the two-phase procedure speeds up motion estimation. As a result, edge-matching first block-matching last algorithm (EFBLA) may significantly save the computation load by 93.9%.     

The Lempel-Ziv algorithm and message complexity

Data compression has been suggested as a nonparametric way of discriminating between message sources. Compressions obtained from a Lempel-Ziv algorithm for relatively short messages, such as those encountered in practice, are examined. The intuitive notion of message complexity has less connection with compression than one might expect from known asymptotic results about infinite messages. Nevertheless, discrimination by compression remains an interesting possibility     

OLRIV: a new fast adaptive algorithm for rectangular-block Toeplitzsystems

In this paper, we propose a new algorithm for solving overdetermined systems when they are rectangular-block Toeplitz (the blocks can have more rows than columns). It is based on the expression of the matrix of the system to solve as the intercorrelation between two vectorial processes, namely, the original and the instrumental processes. The instrumental process has generally more components than the original one; therefore, it takes the overdetermined character of the system into consideration. The proposed algorithm known as the overdetermined lattice recursive instrumental variable (OLRIV) belongs to the fast-RLS family and lies on a double lattice structure, where one lattice performs the prediction of the original process and the other one the prediction of the instrumental process. The geometric complete derivation of the proposed algorithm is given in the paper. Afterwards, we show how OLRIV can be applied to perform blind adaptive identification of AR channels using high order statistics, where the systems to solve are often overdetermined to ensure identifiability. Both the scalar and the vectorial cases are investigated. Simulation results are finally given to show the performances of OLRIV     

Motion estimation algorithm with low complexity for videocompression

The author presents a new motion estimation method which reduces the computational complexity in video compression. This is achieved by skipping the motion estimation operation for macro-blocks, where it is determined that this operation does not need to be carried out     

A fast algorithm for determining the linear complexity of asequence with period pn over GF(q)

A fast algorithm is presented for determining the linear complexity of a sequence with period pⁿ over GF (q), where p is an odd prime, and where q is a prime and a primitive root (mod p²)     

脉压波形畸变校正及其快速算法设计

针对雷达信号实时处理中数字正交插值滤波器引起脉压波形畸变的现象,提出了一种新的波形优化方法,采用精确设计的匹配滤波器,消除了数字正交插值滤波器对脉压波形的失配影响,改进了脉压输出的幅度特性和相位特性,提高了检测性能.基于对任意长度序列进行优化的添零-分解FFT方法,提出了利用频域滤波实现大脉压比脉压的一种新的快速算法,当对非连续信号进行脉压时,显著减轻了运算负荷.     

Vertex component analysis: a fast algorithm to unmix hyperspectral data

Given a set of mixed spectral (multispectral or hyperspectral) vectors, linear spectral mixture analysis, or linear unmixing, aims at estimating the number of reference substances, also called endmembers, their spectral signatures, and their abundance fractions. This paper presents a new method for unsupervised endmember extraction from hyperspectral data, termed vertex component analysis (VCA). The algorithm exploits two facts: (1) the endmembers are the vertices of a simplex and (2) the affine transformation of a simplex is also a simplex. In a series of experiments using simulated and real data, the VCA algorithm competes with state-of-the-art methods, with a computational complexity between one and two orders of magnitude lower than the best available method.     

Adaptive Viterbi algorithm with ARQ for bounded complexity decoding

Adaptive bounded computational and memory requirements for a Viterbi decoder can be achieved using an error trapping Viterbi decoder algorithm initially develop for hybrid automatic repeat request (ARQ) implementations. Partial path metrics and a sliding window are used to eliminate unreliable paths in the decoder trellis thus reducing the computational and memory requirements. An ARQ is issued if all paths are eliminated. The algorithm is adaptive allowing the receiver to dynamically allocate memory and processing, to improve reliability or received packets, or to reject packets with lower reliability to avoid buffer overruns. The result is the ability to trade off resources versus delay and throughput.     

On the performance and complexity of A generalized minimum distance reed–solomon decoding algorithm

The article reports on the characteristics of an algorithm that implements generalized minimum distance (GMD) decoding of Reed-Solomon codes. The algorithm uses the novel Welch-Berlekamp (WB) algorithm, as modified by Tze-Hua, in order to minimize the complexity of the decoder. Both the WB algorithm and the GMD extension of the WB algorithm are described in outline. The performance of the GMD algorithm was simulated on AWGN channels and fading channels. Results are presented both for RS and concatenated RS codes. The gains over conventional decoding are larger for fading channels than for AWGN conditions but seem useful in all cases. The complexities of the GMD algorithm and the WB algorithm are analysed and compared to that of conventional RS decoding algorithms.     

A fast algorithm for a redundancy optimization problem

This paper presents a simple heuristic technique to arrive at the optimal redundancy allocation. There is a drastic reduction in the number of steps because of the criterion evolved, which allows for the addition of one or more units, simultaneously, at more than one stage. Examples have been provided to demonstrate the effectiveness of the technique.