Approximating the Outage Probability of the Pilot Channel for IS‐95‐Based Cellular CDMA Systems in the Soft Handover Region

This letter presents an approximation of the outage probability of the pilot channel that can be used for CDMA cell planning. The approximation can determine system parameters for soft handover in IS‐95‐based cellular CDMA downlink design. Computer simulations show that our analytical results agree with empirical results.     

A new efficient algorithm for computing the imprecise reliability of monotone systems

Reliability analysis of complex systems by partial information about reliability of components and by different conditions of independence of components may be carried out by means of the imprecise probability theory which provides a unified framework (natural extension, lower and upper previsions) for computing the system reliability. However, the application of imprecise probabilities to reliability analysis meets with a complexity of optimization problems which have to be solved for obtaining the system reliability measures. Therefore, an efficient simplified algorithm to solve and decompose the optimization problems is proposed in the paper. This algorithm allows us to practically implement reliability analysis of monotone systems under partial and heterogeneous information about reliability of components and under conditions of the component independence or the lack of information about independence. A numerical example illustrates the algorithm.     

光码分多址接入系统中远近效应的研究

对光码分多址接入系统中由于各个用户距离和发射功率不同导致的远近效应进行研究。结果表明 ,远近效应显著劣化了小功率用户的误码率和掉线率。而且 ,系统中用户的信号功率方差越大 ,各个用户的误码率和掉线率的劣化也越严重。提出了一种应用光硬限幅器消除远近效应的方法 ,该方法还极大地降低了多用户干扰     

瑞利衰落环境下的P-SCDMA系统捕捉性能分析

介绍了分组交换同步码分多址P-SCDMA(Packet-Switch-SynchronousCodeDivisionMul tipleAccess)系统的导频信号模型及其捕捉结构,在给出捕捉性能的理论结果的基础上对其在瑞利衰落环境下进行分析,给出其仿真结果,并和理论结果进行比较。     

Performability indicators for the traffic analysis of wide area networks

In this paper, a repairable circular consecutive-k-out-of-n:F system with one repairman is studied. It is assumed that the working time and the repair time of each component are both exponentially distributed and every component after repair is ‘as good as new’. Each component is classified as either a key component or an ordinary component. Key components have priority in repair when failed. By using the definition of generalized transition probability, the state transition probabilities of the system are derived. Important reliability indices are evaluated for an example.     

Optimizing the QoS of high speed moving terminals in cellular networks

This paper presents a dynamic guard channel assignment technique based on a two‐layer cellular architecture which optimizes the blocking probability performance of high‐speed moving terminals (HSMT) and handoff calls of low‐speed moving terminals (LSMT), in a congested urban area. The lower layer of the proposed architecture is based on a microcellular solution, for absorbing the traffic loads of LSMT. The higher layer is based on a macro‐cell umbrella solution, for absorbing the traffic load of the HSMT. The results show that using the optimum number of channels and adjusting dynamically the number of guard channels in each layer, the blocking probability of the HSMT and the handoff blocking probability of LSMT is optimized having the minimum bad effect on the new call blocking probability of LSMT. Copyright © 2003 John Wiley & Sons, Ltd.     

实验在有线网络运营中的意义

讨论了实验在有线网络运营中的重要地位 ,着重分类介绍了有线网络实验的具体内容和应当注意的问题 ,同时阐述了建立健全实验机制对有线网络发展的现实意义     

Probability of infancy problems for space launch vehicles

This paper addresses the treatment of ‘infancy problems’ in the reliability analysis of space launch systems. To that effect, we analyze the probability of failure of launch vehicles in their first five launches. We present methods and results based on a combination of Bayesian probability and frequentist statistics designed to estimate the system's reliability before the realization of a large number of launches. We show that while both approaches are beneficial, the Bayesian method is particularly useful when the experience base is small (i.e. for a new rocket). We define reliability as the probability of success based on a binary failure/no failure event. We conclude that the mean failure rates appear to be higher in the first and second flights (≈1/3 and 1/4, respectively) than in subsequent ones (third, fourth and fifth), and Bayesian methods do suggest that there is indeed some difference in launch risk over the first five launches. Yet, based on a classical frequentist analysis, we find that for these first few flights, the differences in the mean failure rates over successive launches or over successive generations of vehicles, are not statistically significant (i.e. do not meet a 95% confidence level). This is true because the frequentist analysis is based on a fixed confidence level (here: 95%), whereas the Bayesian one allows more flexibility in the conclusions based on a full probability density distribution of the failure rate and therefore, permits better interpretation of the information contained in a small sample. The approach also gives more insight into the considerable uncertainty in failure rate estimates based on small sample sizes.     

Models for Architectural Power and Power Grid Noise Analysis on Data Bus

The transition activity on a data bus is a time series that determines power consumption on this data bus. The average values of power consumption and power grid voltage drop are proportional to average value of transition activity, i.e., transition probability. The fluctuation of power grid voltage drop appears as noise on power grid and its strength is determined by the second order statistics of transition activity, i.e., variance, auto-correlation function or power spectrum. In this paper, for the first time, simple accurate models for estimating variance and power spectrum of transition activity are proposed. The proposed models are based on linearly modeling spatial-time correlation of bit-level transition activity and result in low computational complexity but very good estimation accuracy. In addition, the dual bit type (DBT) [1, 2] model for estimating average transition activity was further developed. The previous DBT model was made complete with the equation derived in this paper for computing transition probability beyond breakpoint BP ₁. Besides DSP computational architecture and algorithm designs, the proposed simple models are of great significance for power grid noise decoupling and chip floor-planning. Lijun Gao (S’99–M’01) received B.E. and M.E. degrees in Communication & Electronic Systems from Tsinghua University, Beijing, China, in 1986 and 1988, respectively. He received his PhD degree in Elecrical & Computer Engineering from University of Minnesota, Minneapolis, USA, in 2001. He is also an MS degree candidate in Computer & Information Science at University of Minnesota, Minneapolis. Dr. Gao is currently with Medtronic Inc., Minneapolis, MN, and working on DSP design for pacemaker. From 2001 to 2003, he was with Bermai Inc., Minnetonka, MN and working on the design of wireless LAN (802.11a/11b) chipsets. In 2001, he worked in the R & D division of GlobeSpan Semiconductor Inc., Red Bank, NJ. From 1988 to 1991, he was a faculty member with Tsinghua University, Beijing, China. From 1991 to 1996, he was a R & D engineer with the Institute of Software, Chinese Academy of Science, Beijing, China. For the period of 1991 to 1993, he was a visiting R & D engineer at Onflo Computer Co. Hong Kong. Dr. Gao received the Science & Technology awards from the National Education Council, China, in 1994 for his contribution to radar signal processing while he was at Tsinghua University, and from the ministry of Electronic Industry, China, in 1995 for his contribution to the CJK Ideograph Unification in ISO 10646 (Unicode). His current reserach interest includes the algorithm/architecture/ circuit for VLSI design, the computational aspects of digital signal processing (DSP) and programmable DSP processor. Specifically, his focus is on the deep-submicron VLSI design, power estimation/low power design, computer arithmetic, finite field arithmetic, error control coding, cryptography, adaptive filters, equalization, beamformer, special-purpose processors and FPGA/reconfigurable computing. Keshab K. Parhi (S’85-M’88–SM’91-F’96) Keshab K. Parhi received his B.Tech., MSEE, and Ph.D. degrees from the Indian Institute of Technology, Kharagpur, the University of Pennsylvania, Philadelphia, and the University of California at Berkeley, in 1982, 1984, and 1988, respectively. He has been with the University of Minnesota, Minneapolis, since 1988, where he is currently Distinguished McKnight University Professor in the Department of Electrical and Computer Engineering. His research addresses VLSI architecture design and implementation of physical layer aspects of broadband communications systems. He is currently working on error control coders and cryptography architectures, high-speed transceivers, ultra wideband systems, quantum error control coders and quantum cryptography. He has published over 350 papers, has authored the text book VLSI Digital Signal Processing Systems (Wiley, 1999) and coedited the reference book Digital Signal Processing for Multimedia Systems (Marcel Dekker, 1999). Dr. Parhi is the recipient of numerous awards including the 2004 F.E. Terman award by the American Society of Engineering Education, the 2003 IEEE Kiyo Tomiyasu Technical Field Award, the 2001 IEEE W.R.G. Baker prize paper award, and a Golden Jubilee award from the IEEE Circuits and Systems Society in 1999. He has served on the editorial boards of the IEEE TRANSACTIONS ON CAS, CAS-II, VLSI Systems, Signal Processing, Signal Processing Letters, and currently serves on editorial board of the IEEE Signal Processing Magazine, and is the curent Editor-in-Chief of the IEEE Trans. on Circuits and Systems–I (2004–2005 term). He has served as technical program cochair of the 1995 IEEE VLSI Signal Processing workshop and the 1996 ASAP conference, and as the general chair of the 2002 IEEE Workshop on Signal Processing Systems. He was a distinguished lecturer for the IEEE Circuits and Systems society during 1996–1998. He currently serves on the Board of Governors of the IEEE Circuits and Systems Society. He was elected a Fellow of IEEE in 1996.