Calculating Error Probabilities for Intersymbol and Cochannel Interference

The probability of error in a binary symmetric channel with intersymbol interference and additive noise is efficiently calculated by numerical quadrature of a Laplace inversion integral along a contour in the complex plane passing through a saddlepoint of the integrand. For Gaussian noise, a bound is set on the truncation error incurred by necessarily restricting the integration to a finite interval. The probability of error resulting from cochannel interference is calculated by a similar technique.     

数字通信系统中一种新型差错控制方案

对当今主流数字通信系统中的差错控制技术进行了分析,并针对其不足提出了一种新型差错控制方案.利用两条信道同时传输数字信息,传送的信息相位相反,信息中无监督码元,在接收端利用差分技术对这两个信号进行处理.分析表明,该方案在信号的传信率、误码率和编码效率指标上优于传统差错控制技术,且实现更为简单.     

Techniques for Estimating the Bit Error Rate in the Simulation of Digital Communication Systems

Computer simulation is often used to estimate the bit error rate (BER) performance of digital communication systems. There are a number of distinct techniques in the simulation context that can be used to construct this estimate. A tutorial exposition of such techniques is provided, with particular reference to five specific methods which can be implemented in a simulation. These methods range from the traditional Monte Carlo trials to assumption of definite forms for the noise statistics. An attempt is made to show how these methods are related, and the specific assumptions that are invoked in order to apply them.     

A Modified Monte-Carlo Simulation Technique for the Evaluation of Error Rate in Digital Communication Systems

Digital communication systems are frequently operated over nonlinear channels with memory. The analysis of the performance of these systems is difficult and no complete analytical treatment of the problem has been obtained before. Several recent efforts have been directed toward the computation of error probabilities via Monte-Carlo simulation using a complete system model. These simulations require excessively large sample sizes and are not practical for estimating very low values of error probabilities. This paper presents a modified Monte-Carlo simulation technique for estimating error probabilities in digital communication systems operating over nonlinear channels. An importance-sampling technique is used to modify the probability density function of the noise process in a way to make simulation possible. Theoretical results as well as realistic examples are presented, showing that the number of samples needed for simulation is reduced considerably.     

Polarization-Dependent Loss-Induced Outage Probabilities in Optical Communication Systems

Polarization-dependent loss (PDL)-induced outage probabilities (OPs) in optical communication systems are investigated using a semi-analytical method, taking into account the different statistics of the noise parallel and orthogonal to the signal. We show that in today's optical communication systems that typically operate at low optical signal-to-noise ratio due to the use of forward-error-correction coding, neglecting the orthogonal noise or the different statistics between the orthogonal and parallel noise significantly underestimates or overestimates PDL impairments. We find that PDL impairments are larger at lower optical signal-to-noise ratio. Required system margins at an OP of 10^-5 for given PDL values are calculated.     

数字移动通信中的安全问题

本文论述了数字移动通信系统中的几个安全问题：会话的保密性，移动单元与基站之间的相互确认，以及移动单元的难以跟踪性等。并提出了一种新的且适合于移动通信特点的密钥分发方案，以此为基础，可以实现双人通信或电话会议的保密。     

Error Probabilities for Orthogonal Multiplex Systems in the Presence of Intersymbol Interference and Gaussian Noise

The transmission model for anN-dimensional system is extended to handle additive noise and timing error. An orthogonal multiplex system operating in the presence of additive noise and channel introduced inter- and intra-symbol interference is analyzed. Error probabilities are derived and results are reported for carder sets comprising trigonometric product waveforms, Walsh functions, parabolic cylinder functions, and prolate spheroidal wave functions.     

Traffic Models and Blocking Probabilities for Two-Fold and Three-Fold SDMA Communication Systems

Spectrum efficiency is a constant challenge in the design of wireless networks. Space-division-multiple-access (SDMA) is a promising approach to achieve higher spectral efficiency which reuses bandwidth via multiplexing signals based on their spatial signature. Several different studies have shown that SDMA can effectively improve system capacity in a mobile environment. In this paper, we present a new Markov chain traffic model for a duplicate-at-last (DL) approach [IEE Proceedings on Communication 146 (1999) 303] in two-fold and three-fold SDMA systems. Simplified blocking probability formulations for two-fold and three-fold SDMA are also derived. Simulations based on a common method of spatial separation check for channel allocation in SDMA are presented to evaluate the probability of successfully creating two-fold and three-fold SDMA channels. The simulation, as well as analytical, results indicate that the SDMA system can reduce the blocking probability of the calls and result in more traffic loading than a traditional cellular system. The results also show that our simplified approaches not only can reduce the computational complexity, but can also accurate approximate two-fold and three-fold SDMA performance. Wen-Jye Huang received the B.S. degree in electrical engineering from Tatung Institute of Technology, Taipei, Taiwan, in 1991, the M.S. degree in electrical engineering from Ohio University, Athens, OH, in 1997, and the Ph.D. degree in electrical engineering from The Pennsylvania State University, University Park, PA, in 2001. Since 2002, he joined the Department of Electrical Engineering, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan, as an assistant professor. His research activities include smart antenna, SDMA, and MC-CDMA techniques. John F. Doherty received the B.S. degree (with honors) in engineering science from the College of Staten Island, City University of New York, in 1982, the M.Eng. degree in electrical engineering from Stevens Institute of Technology, Hoboken, NJ, in 1985, and the Ph.D. degree in electrical engineering from Rutgers University, New Brunswick, NJ, in 1990. He was an integrated circuit reliability engineer with IBM, from 1982 to 1984. From 1985 to 1988, he was member of the technical staff at AT&T Bell Laboratories, working in sonar signal processing. In 1990, he joined the Electrical and Computer Engineering Department, Iowa State University, Ames, as an assistant professor and Harpole Entair fellow. He is currently an associate professor of electrical engineering with The Pennsylvania State University, University Park. His current research activities include interference rejection in wireless communication systems, spatial-division multiple-access techniques, and radar target detection techniques. He is a former AFOSR summer faculty research fellow at the Rome Laboratory, Rome, NY, and an Army Research Office Young Investigator.     

IMPATT-Diode Power Amplifiers for Digital Communication Systems

lMPATT-diode amplifiers with a power output of 1.0 W have been developed for use in an 11-GHz digital radio. Two types of amplifiers, a multistage reflection amplifier and a hybrid amplifier containing an injection-locked oscillator stage, have been evaluated by measuring the bit error rate degradation due to the amplifier. System test data show that the stable amplifier introduces little or no errors while the injection-locked oscillator (ILO) often introduces an error-rate floor.     

汉明码在多载波CDMA系统中的应用

本文讨论了GMC-CDMA技术。GMC-CDMA提供了全数字、统一的结构，包含了单载波和多载波CDMA系统。然后，本文用信道编码对GMC-CDMA技术改进，采用在GMC-CDMA系统前先进行蝙码采确保低误码率。仿真结果会表明：经过编码后的系统能取得更低的误码率。图像在编码的GMC-CDMA和未编码的GMC—CDMA两个系统中的不同传输效果进一步验证了这一结论。     

Error Categorization and Analysis in Man-Computer Communication Systems

This paper briefly examines traditional approaches to human reliability and presents a technique which permits the system designer to derive a mutually exclusive and exhaustive set of operator error categories in a man-computer system. These error categories are defined in terms of process failures and provide the system designer with a qualitative index suitable for determining error causes and consequences. The technique is demonstrated, and the utility of the resulting error categories is evaluated in the context of two studies on a military information processing system. The paper concludes with a brief discussion of detectable and non-detectable errors and a suggestion for determining the impact of errors on ultimate system goals.     

Efficiency of Digital Synchronous Communication Systems

A novel criterion for digital synchronous communication system efficiency estimation is defined. All system attributes such as bit error probability, coding efficiency, initial system synchronization time, efficiency of detection of timing anomalies and system sync recovery, reliability of the lock indication, and the amount of redundancy insertion in the data stream for synchronization and error-correcting coding purposes are included in a single parameter called "system efficiency." The expression for this parameter is derived under the assumption of signal ergodicity and steady-state system operation. In its final form, this parameter seems obvious almost by inspection. Even so, until now, it has not been used in the analysis of communication system efficiency. The analysis of this parameter for several different systems is presented as an illustration.     

Error Rate Lower Bounds for Digital Communication with Multiple Interferences

This paper presents simple and general lower bounds for error rates in digital communication systems. The information bearing signal is taken to be impaired by additive interference and carrier phase jitter. The former is taken to be composed of two components; one component is peak-limited while the other is not. Intersymbol and cochannel interference are examples of peak-limited interference while additive thermal noise is an example of a nonpeak-limited interference. The novelty of the paper is in the generality of the results and in obtaining a simple error bound for transmission in the presence of cochannel interference and carrier phase jitter.     

Bit Error Probability for Baseband and Subcarrier Optical Communication Systems

Digital baseband and digital subcarrier noncoherent optical communication systems are considered in this paper. Expressions are developed for the bit error probability of optical subcarrier systems which use a nonliner polarization modulator and either a one-detector or a two-detector receiver, The expressions are evaluated numerically, and the results are used to compare the one- and two-detector subcarrier systems with the corresponding one- and two-detector baseband systems for a fLxed bit error probability.     

扩频通信系统的中频数字化处理技术

介绍了一种应用于抗干扰综合信息系统的数字扩频通信系统 ,具体讨论了利用匹配滤波器完成PN码的快速捕获和利用谱估计完成载频的频移补偿的数字化处理技术 ,系统可以实现远距离的无线数据通信 ,文中给出了中频数字部分的实现原理以及软硬件框图。     

低成本、适合无线通信的语音编石码芯片-CMX639

本文首先介绍了连续可变斜率增量调制(CVSD)的工作原理和性能,并与当前应用较为广泛的其它语音编码方 法进行分析比较,接着重点介绍了美国国家半导体公司的CVSD语音编码芯片-CMX639,并给出无线耳麦的整 体设计方案。