Intersymbol Interference with Orthogonal Signaling

The occurrence of both inter- and intrasymbol interference in a communications system utilizing orthogonal signals and memoryless correlation detection is described, and a system model is presented. A relationship between a bound on peak interference and time-bandwidth product for several well known orthogonal signal sets is reported.     

Signaling Performance Over a Piecewise Linear Limited Channel in the Presence of Interference and Gaussian Noise

Presented here are a model and the analysis for evaluating bit error probability of a BPSK signal transmitted through a band-limited piecewise linear (PWL) limited satellite channel subject to continuous wave (CW) interference as well as additive Gaussian noise. The CW interference is assumed to have a random phase over (0, 2pi) and a fixed frequency fjwhich may be either in or out of the signal band. The analysis is carried out by first formulating a conditional error probability on the uplink channel noise and the CW interference phase and then averaging over the appropriate random variables through conventional Gaussian quadrature formulas and the moment technique used in [2]. Numerical results for the error rate performance are compared to those of hard-limited channels. The results indicate that a PWL limited channel outperforms a hard-limited channel when the out-of-band CW interference power is close to or greater than the desired signal.     

Fast Error Rate Evaluation in the Presence of Intersymbol Interference

In this paper, we present a general framework which describes a class of fast methods of error rate evaluation in the presence of additive noise and intersymbol interference. An analysis of this framework led us to propose a new method based on a Fourier series expansion which does not make use of the moments of the intersymbol interference. Its computing cost is low and it handles various kinds of noise as well as current coherent amplitude or phase modulation techniques.     

On Differential Detection of M-ary DPSK with Intersymbol Interference and Noise Correlation

In this paper we study differential detection ofM-ary differential phase-shift-keyed (DPSK) signals with intersymbol interference and noise correlation. With these impairments there can be a wide variation in the error rate of the individual symbols, with this variation increasing withM. However, by adding a phase shift offset and adjusting the decision boundaries in the detector, this variation can be reduced and the average symbol error rate can be decreased. For example, for quaternary DPSK with a signal to adjacent (from the previous and next symbols) intersymbol interference power ratio of 17 dB, these methods can reduce the variation in symbol error rates by more than two orders of magnitude and decrease the required signal-to-thermal noise ratio for a 10^-6symbol error rate by more than 2 dB.     

Linear Direct-Detection Fiber-Optic Receiver Optimization in the Presence of Intersymbol Interference

A technique is developed for optimizing communication receivers by minimizing a Chernoff bound (CB) on the Bayes cost function. Being couched in terms of moment generating functions, the procedure is well suited to optical systems. Optimal CB receivers are derived and shown to coincide exactly with known minimum cost Bayes receivers for certain special cases of both electrical and optical communications for which closed form analytic solutions are possible. This provides endorsement for the method, which is then applied to more complex practical cases of linear optical fiber receivers in which both colored Gaussian noise and intersymbol interference play a part. The CB receivers are shown to offer some improvement compared with a zero forcing raised cosine equalizing receiver such as is commonly adopted, and all the evidence suggests that CB receivers achieve performance very close to the best possible with a linear receiver.     

Wide-Band Frequency-Shift Keyed Receiver Performance in the Presence of Intersymbol Interference

The noncoherent binary frequency-shift keyed (FSK) receiver analyzed in this concise paper employs predetection filters with bandwidths much larger than the symbol rate. Wide-band predetection filtering is used in order to trade performance for simplicity and reduced costs. In this analysis bit-error rate (BER) degradation due to wide predetection filter bandwidths and intersymbol interference caused by postdetection filtering is determined. The postdetection filters considered are single-pole RC and two-pole Butterworth filters. The receiver performance using these filters is compared with the performance achieved when using integrate-and-dump postdetection filtering. Experimental and simulation results are presented which agree well with the analysis.     

Effects of Intersymbol Interference on a Rayleigh Fast-Fading Channel

It is shown in this paper that the performance of certain Rayleigh fast-fading channels can be accurately and efficiently evaluated using the elementary trapezoidal integration rule. The effects of intersymbol interference on such channels are analyzed.     

Lower Bounds on Error Probability in the Presence of Large Intersymbol Interference

A lower bound on the symbol error probability achieved by any estimator of a digital pulse-amplitude-modulated sequence in the presence of white Gaussian noise and intersymbol interference is presented. The bound reduces to the well-known single-pulse error probability bound when intersymbol interference is small, but is tighter when interference is large. For example, on the singlepole (RC) channel, the effective signal-to-noise ratio for any estimator is shown to decrease by at least 3 dB for every doubling in pulse rate T^-1asT rightarrow 0and, on the double-pole channel, by at least 9 dB, thus disproving a recent conjecture [2] on the performance of nonlinear receivers.     

Analysis of Four Decision-Feedback Carrier Recovery Loops in the Presence of Intersymbol Interference

The performance of four decision-feedback carrier recovery techniques is evaluated in the presence of additive noise and intersymbol interference (ISI). For QAM signal constellations, a closed-form expression is given for the phase jitter variance (PJV) of each loop, and the loop tracking performance is examined. The analytic results are then computed in the case of a 16 QAM digital radio system subjected to multipath fading. Two cases are considered: in the first case no countermeasure techniques are used against selective fading, while in the second case a three-coefficient decision-feedback equalizer (DFE) is used. Computer simulations using a pseudorandom sequence to estimate loop performance are also reported which support the theoretical results.     

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.     

Error Probability in the Presence of Intersymbol Interference and Additive Noise for Multilevel Digital Signals

A new method is presented to compute the average probability of error in the presence of intersymbol interference and additive noise for multilevel pulse-amplitude-modulation (PAM) and partial-response-coded (PRC) signaling schemes. The method is based upon nonclassical Gauss quadrature rules (GQR) and suffers no limitation on noise statistics, so that it applies also for non-Gaussian noise. Moreover it yields some remarkable advantages as compared with other methods, in particular, with the series expansion method that has recently received considerable attention. Expressions for the truncation error are also given and their derivation is reported in the Appendix. Finally, examples of applications are presented and comparisons with other methods are carried out.     

Intersymbol Interference in an FM-DCPSK System

A digital computer simulation of a frequency-modulation differentially coherent phase-shift-keying (FM-DCPSK) system is described. This simulation program is used to investigate the effect of intersymbol interference on the error-rate performance of the two- and four-phase system. Nyquist channels have been obtained and verified. Performance curves are presented to facilitate system design.     

On the Probability Density of Intersymbol Interference

The paper presents a simple and rapid algorithm for numerically evaluating the probability density function (pdf) of intersymbol interference (ISI) in digital transmission systems. The results coincide with the analytical solutions available for very few cases only. The biterror rate calculated from the pdf's of ISI and of Gaussian noise agree with upper and lower bounds as published by many authors. Examples of the pdf of ISI in some cases of practical interest are given for various QAM-modulation schemes.     

数字传输中的码间干扰仿真研究

在当前信息时代,数字化得到飞速发展,模———数转换技术已得到普遍应用,同时数字信号的传输也成为一个重要的课题。本文将研究仿真基带传输系统中的数字基带信号码型选择、波形表示,以及这种随机二进制基带信号功率谱特性,另外码符号间可能出现的干扰即码间干扰的消除与码元同步等基本问题的仿真将是重点。     

无线通信中消除码间干扰的研究

介绍了码间干扰以及消除码间干扰常用的三种方法.并从理论上比较了三种方法的性能,为了测试验证单载波频域均衡系统的性能,搭建了仿真系统进行了计算机仿真模拟.其仿真结果表明:与时域均衡相比较,频域均衡能有效提高均衡器的收敛速度和显著改善均衡器消除符号间干扰(ISI)的性能.     

Cochannel and Intersymbol Interference in Quadrature-Carrier Modulation Systems

A method is presented for determining the performance of a quadrature-carrier modulation system in terms of probability of error in the presence of additive white Gaussian noise, intersymbol interference, and cochannel interference. This method has been applied to determine the error rate of several quadrature-carrier modulation systems using Butterworth receiving filters of different orders. It has been foand that among the different quadrature-carrier modulation systems studied, sinusoidal frequency-shift keying seems to exhibit the best overall performance in a cochannel and intersymbol interference environment. These results are shown through a number of performance curves that provide useful data for the systems designer.