Analysis of a cutoff priority cellular radio system with finitequeueing and reneging/dropping

Queueing of new or handoff calls can minimize blocking probabilities or increase total carried traffic. This paper investigates a new cutoff priority cellular radio system that allows finite queueing of both new and handoff calls. We consider the reneging from the system of queued new calls due to caller impatience and the dropping of queued handoff calls by the system as they move out of a handoff area before being accomplished successfully. We use signal-flow graphs and Mason's formula to obtain the blocking probabilities of new and handoff calls and the average waiting times. Moreover, an optimal cutoff parameter and appropriate queue sizes for new and handoff calls are numerically determined so that a proposed overall blocking probability is minimized     

Analysis of a Mobile Radio Communication System with Two Types of Customers and Priority

In this paper an analytical method is developed to determine the performance of a system with two types of customers and "cutoff" priority. A completely recursive solution and a solution involving matrix inversion are provided. Some examples from the mobile radio communication system are considered to illustrate applications of the method. This paper is an extension of the case for equal service rate for the two classes.     

快速二维直方图斜分最小误差的图像阈值分割

鉴于二维斜分法的优势,提出了一种快速二维直方图斜分最小误差的阈值分割方法。首先将二维直方图斜分原理运用到最小误差阈值法中使得分割更准确,然后对其阈值选取公式进行简化得到最简公式,并利用此公式导出其一般递推算法,最后将二维直方图概率分布特性与这种算法有机结合得到新型的递推算法来提高运行速度。实验结果表明,与二维直线型最小误差阈值分割法相比,算法效率更高,与其递推算法相比,所提出的新型递推算法的运行速度更快,约快4倍。     

任意长离散余弦变换的快速递归算法

该文基于Clenshaw递归公式以及离散余弦自身的对称性提出任意长离散余弦变换(DCT)的一种并行递归快速算法,给出了该算法的滤波器实现结构;与现有的其它递归算法以及基于算术傅里叶变换的余弦变换算法进行了计算复杂度的比较分析,结果表明该文算法运算量大大减少。该递归计算的滤波器结构使算法非常适合大规模集成电路(VLSI)实现。     

频率无偏估计的有限冲激响应自适应陷波器方法研究

针对现有自适应陷波器频率估计方法结构复杂、抗噪性弱、结果有偏的问题,提出频率无偏估计的有限冲激响应自适应陷波器方法.该方法首先以结构较为简单的FIR自适应陷波器为基础,在分析其误差函数性能的基础上,提出频率估计的迭代递推计算式,提升频率估计的收敛性能;其次,对该频率估计迭代递推计算式进行偏差分析,在分析出偏差产生的原因...     

l0-范数约束的稀疏多径信道RLS常模盲均衡算法

针对稀疏多径信道下MPSK信号的快速盲均衡问题,提出了一种l0-范数约束的递归最小二乘常模盲均衡算法.该算法借鉴传统的递归最小二乘常模盲均衡算法思想,结合稀疏自适应滤波理论,首先利用l0-范数对均衡器抽头系数进行稀疏性约束,构造出一种l0-范数约束的加权最小二乘误差代价函数,然后依据递归最小二乘算法推导出均衡器抽头系数更新公式.该算法发挥递归最小二乘常模算法收敛速度快的优势,并对幅度极小系数附加零点吸引调整,从而实现不同幅度抽头系数的快速收敛.理论分析与仿真结果表明,与现有算法相比,该算法在保证较低剩余符号间干扰的前提下,能有效提高均衡器的收敛速度.     

灰度图像的二维交叉熵直线型阈值分割法

 一维Otsu法是一个经典的阈值分割方法,遵循该方法的构造思想,Li 与 Lee基于交叉熵提出了一个阈值分割方法.在解释和说明Li 与 Lee的方法的基础上,与二维Otsu直线型阈值分割方法相对应,提出二维灰度直方图上的二维交叉熵直线型阈值分割方法并给出快速递推公式.与二维Otsu直线型阈值分割法相比,新方法能够更好的适应目标和背景方差相差较大的情形,是一个有效的阈值分割方法.     

Analysis of a hybrid cutoff priority scheme for multiple classes of traffic in multimedia wireless networks

In this paper, we propose and analyze the performance of a new handoff scheme called hybrid cutoff priority scheme for wireless networks carrying multimedia traffic. The unique characteristics of this scheme include support for N classes of traffic, each may have different QoS requirements in terms of number of channels needed, holding time of the connection and cutoff priority. The proposed scheme can handle finite buffering for both new calls and handoffs. Futhermore, we take into consideration the departure of new calls due to caller impatience and the dropping of queued handoff calls due to unavailability of channels during the handoff period. The performance indices adopted in the evaluation using the Stochastic Petri Net (SPN) model include new call and handoff blocking probabilities, call forced termination probability, and channel utilization for each type of traffic. Impact on the performance measures by various system parameters such as queue length, traffic input and QoS of different traffic has also been studied. This revised version was published online in June 2006 with corrections to the Cover Date.     

Self-tuning distributed measurement fusion Kalman estimator for the multi-channel ARMA signal

For the multisensor multi-channel autoregressive moving average (ARMA) signal with white measurement noises and a common disturbance measurement white noise, when the model parameters and the noise variances are all unknown, a multi-stage information fusion identification method is presented, where the consistent fused estimates of the model parameters and noise variances are obtained by the multi-dimension recursive instrumental variable (RIV) algorithm, correlation method and Gevers-Wouters algorithm with a dead band. Substituting these estimates into the optimal distributed measurement fusion Kalman signal estimator, a self-tuning distributed measurement fusion Kalman signal estimator is presented. Its convergence is proved by the dynamic error system analysis (DESA) method, so that it has asymptotical global optimality. In order to reduce computational load, a fast recursive inversion algorithm for a high-dimension matrix is presented by the inversion formula of partitioned matrix. Especially, when the process and measurement noise variance matrices are all diagonal matrices, the inversion formula of a high-dimension matrix is presented, which extends the formula of the inverse of Pei-Radman matrix. Applying the proposed inversion algorithm, the computation of the fused measurement and fused noise variance is simplified and their computational burden is reduced. A simulation example shows effectiveness of the proposed method.     

Computing consecutive-type reliabilities nonrecursively

The reliability of consecutive-type systems has been approached from various angles. A new method is presented for deriving exact expressions for the generating functions and the reliabilities of various consecutive-type systems. This method, based on Feller's run theory, is easy to implement, and leads to both recursive and nonrecursive formulas for the reliability. The nonrecursive expression is especially advantageous for systems with numerous components. In comparison to the n (number of components) computations that the recursive formulas require, the nonrecursive formula only requires the computation of the roots of a polynomial of order k. The method is extended for computing generating functions and reliabilities of systems with multi-state components as well as systems with s-dependent components.     

A Recursive Recomputation Approach for Smoothing in Nonlinear State–Space Modeling: An Attempt for Reducing Space Complexity

In this paper, we develop a new generic implementation scheme for numerical smoothing in nonlinear and Bayesian state-space modeling. Our new generic implementation scheme, which we call recursive recomputation scheme, reduces the space complexity from O(MT) to O(M log T), at the cost of O(log T) times computation of filtering distributions in time complexity. This reduction is accomplished by employing carefully designed recursive recomputation. The Japanese stock market price time-series data with T = 956 is taken up as an instance to demonstrate advantage of the proposed scheme. The path-sampling particle smoother is implemented with the scheme to smooth the whole interval estimating the change of volatility. The number of particles is 3 000 000, and the whole interval is smoothed with 5.3-GB storage, accomplishing saving of storage by a factor of 1/20. The computed smoothing distribution is compared with the ones computed with the existing two other well-known smoothers, the forward-backward smoother and the smoother based on two-filter formula. It turns out that, among the three, ours is the only method which succeeded in computing a reliable and plausible smoothing distribution in the situation.     

二维直线型最小误差阈值分割法

一维最小误差阈值法假设了目标和背景的灰度分布服从混合正态分布。考虑到噪声等因素对图像质量的影响,该文在二维灰度直方图上,基于二维混合正态分布假设,给出二维直线型最小误差阈值法的表达式。为了提高算法的运行速度,也给出了快速递推算法。实验表明,二维直线型最小误差阈值法是一个有效的图像分割算法,能够更好地适应目标和背景方差相差较大的含噪图像分割问题。     

Propagation Characteristics of an Elliptically-cored Highly Birefringent Fiber using an Analytical Method

By using the method of separation of variables in the elliptical coordinate system, a representative formula in terms of Mathieu and modified Mathieu functions is derived and longitudinal field components for the even and odd modes are presented for the proposed fiber. The eigen value equation for the fiber to be considered is obtained by solving the fourth order determinantal equation under weak guidance condition and is given in this paper. The cutoff frequency of several lower orders modes for different eccentricities have been obtained and their propagation characteristics have been plotted. The effect of the eccentricity on the modal cutoff values and mode transmissions is discussed. Finally, the modal birefringence in the proposed fiber is also estimated.     

Fast algorithm for computing discrete cosine transform

An efficient method for computing the discrete cosine transform (DCT) is proposed. Based on direct decomposition of the DCT, the recursive properties of the DCT for an even length input sequence is derived, which is a generalization of the radix 2 DCT algorithm. Based on the recursive property, a new DCT algorithm for an even length sequence is obtained. The proposed algorithm is very structural and requires fewer computations when compared with others. The regular structure of the proposed algorithm is suitable for fast parallel algorithm and VLSI implementation     

基于优先级降低策略的回卷恢复容错实时调度算法研究

实时系统中任务的超时完成将会导致灾难性后果,因此实时系统必须具备实时性和可靠性保障。为了提升系统的容错能力,该文基于回卷恢复容错模型,提出了容错优先级降低策略,并基于此策略对系统进行可调度性分析,推导出了任务最坏响应时间的计算公式。为了快速确定一组最优的容错优先级降低配置,该文提出了一种有效的搜索算法,该算法能够将容错优先级降低配置的搜索空间由O(n!)降低为O(n2)。最后,仿真实验表明容错优先级降低策略可以显著提升系统的容错能力。     

多层手征介质填充圆波导的分析

本文利用递推本征函数法分析了多层手征介质填充圆波导的传播特性.文中给出了不同介质层中电磁场的递推关系,推导了N层手征介质填充圆波导色散特性的一般性计算公式.作为示例,文中还给出了对几种结构传播特性的计算结果.     

AKF与EFRLS在动态目标跟踪性能上的比较

卡尔曼滤波是具有递推估计形式的最优滤波,但最优性的获得是在过程噪声和观测噪声统计特性已知的前提下得到的。然而,在大量的动态目标跟踪实际问题中噪声具有不确定性,因而有必要研究在噪声不确定下动态目标的跟踪算法以满足实际问题的需要。文中介绍自适应Kalman滤波对过程噪声方差的估计以及推广的遗忘因子最小二乘法对状态估计的递推公式,并且在平均误差最小准则下通过计算机仿真比较两种方法对动态目标的跟踪性能.仿真结果表明,在不确定噪声下自适应Kalman滤波能够取得比推广的遗忘因子递推最小二乘法更好的跟踪性能。     

Serial Concatenation of Space‐Time and Recursive Convolutional Codes

We propose a new serial concatenation scheme for space‐time and recursive convolutional codes, in which a space‐time code is used as the outer code and a single recursive convolutional code as the inner code. We discuss previously proposed serial concatenation schemes employing multiple inner codes and compare them with the new one. The proposed method and the previous one with joint decoding, both performing a combined decoding of the simultaneous output signals from multiple antennas, give a large performance gain over the separate decoding method. In decoding complexity, the new concatenation scheme has a lower complexity compared with the multiple encoding/joint decoding scheme due to the use of the single inner code. Simulation results for a communication system with two transmit and one receive antennas in a quasi‐static Rayleigh fading channel show that the proposed scheme outperforms the previous schemes.     

二维滑动矩形窗傅氏变换的快速递推算法

该文利用相邻滑动窗数据之间的关系以及傅氏变换的平移性质,提出一种二维滑动矩形窗傅氏变换的快速递推算法。文中分析了该快速递推算法的复杂度和传统直接计算法的复杂度,证明了新的快速递推法可以大大降低计算复杂性,尤其是在图像尺寸和窗口尺寸较大的场合中。该算法可以改善滑窗傅氏变换或Gabor变换的计算效率。