DPSK Signaling Over Hard Limiting Channel in the Presence of Intersymbol Interference

This paper considers the performance evaluation of binary differentially-phase-shift-keyed signals which have been transmitted through a hard limiting channel in the presence of intersymbol interference and additive Gaussian noise. An expression for the probability of error is derived which is in the form of an infinite series. In the analysis, the effects of Gaussian noise in the uplink and downlink are taken into consideration. The intersymbol interference is assumed to be present in the uplink only. In order to illustrate the applicability of the method, numerical results are computed for a channel which employs a Butterworth filter.     

Differential Detection with Intersymbol Interference and Frequency Uncertainty

In this paper we study differential detection of binary differential phase shift keyed (DPSK) signals with several impairments typical in satellite communication systems. In particular, the bit error rate is determined for bit timing error and frequency offset error at the receiver. The effect of a hard-limiting, band-limited repeater is also considered. The differential detector performance is determined for both conventional DPSK signals (with 0 and π phase shifts) and symmetrical DPSK signals (with- pi/2and+ pi/2phase shifts). With symmetrical DPSK, adjacent bit signals are orthogonal rather than either in or out of phase. Therefore, with intersymbol interference, the error rates for all bits are equal and the average bit error rate is less with symmetrical DPSK, as shown in this paper.     

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.     

Performance of Multiphase CPSK Systems with Intersymbol Interference

An upper bound on the probability of error for multiphase coherent phase-shift-keying (CPSK) systems with intersymbol interference and additive Gaussian noise is presented. The bound is derived through the Chernoff bounding technique and is given by a simple closed-form expression. To demonstrate its applicability the bound is computed for quaternary and octonary CPSK systems with various "typical" pulse responses. Graphical comparisons with other measures of the probability of error show the relative efficacy of the bound.     

码间干扰的消除研究

在数字信号的基带传输过程中,信息传输速率在满足香农公式的条件下还极大地受到码间干扰的限制。为消除码间干扰,就必须使信息传输速率和系统带宽之间产生确定比例的约束关系,从而使系统的频带利用率也受到限制。运用系统冲激响应过零点消除码间干扰的方法对几种常见的基带系统和部分响应系统进行分析,直接给出其消除码间干扰和获得最大频带利用率的方法,为实际的应用提供一种理论指导。     

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.     

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。     

Intersymbol Interference as a Natural Code

The classical approach of considering intersymbol interference as a modulation problem is replaced by less conventional information decoding considerations. We present the concept of viewing time-dispersive channels as natural convolutional encoders. Several channels are presented as examples and computer simulations exhibit some of the benefits.     

Matched-Transmission Technique for Channels With Intersymbol Interference

A new transmission scheme for channels with intersymbol interference named "matched-transmission (MT) technique" is proposed. An implementation of the MT system is presented and its relations with conventional techniques are described. It is shown that the partial response scheme is a special case of our new technique. The performance of the MT technique is discussed from the view point of the output signal-to-noise ratio and the system is shown to attain asymptotically the bound performance predicted by the information theory.     

Intersymbol Interference Performance of Systems with Correlated Digital Signals

For a digital system with correlated digital symbols, we derive upper and lower bounds on the probability of error when the system is subject to intersymbol interference and additive Gaussian noise. The bounds are expressed in terms of the error probability obtained with a finite number of intersymbol interference terms and some parameters associated with the remainder terms. We also show that the difference between the upper and lower bounds can be made arbitrarily small and that the error probability can be computed to any desired degree of accuracy. We give some examples to illustrate the method.     

Intersymbol Interference in Binary Communication Systems with Single-Pole Band-Limiting Filters

The exact value of the probability of error is computed for binary communication systems with sampling detector or integrating-and-dumping detector, with nonreturn-to-zero or split-phase signals and single-pole filters in the receiver and transmitter. The effect of nonoptimal sampling time on the probability of error is presented.     

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.     

Decision-Aided Tracking Loops for Channels with Phase Jitter and Intersymbol Interference

The theory of decision-aided carrier tracking loops as developed by Lindsey and Simon is extended to include the effects of intersymbol interference. A major theoretical result is the solution of the Fokker-Planck equation for the probability density function (pdf) of the phase error for a first-order tracking loop. This function is used to average upper and lower bounds on the demodulator error rate so that an estimate of the overall system error rate may be obtained. The modulation technique analyzed is double-sideband-pulse-amplitude pulse-amplitude modulation. Curves are presented which display the threshold performance of the system error rate at low modulation index.     

Lower Bounds for Finite Intersymbol Interference Error Rates

Some simple lower bounds for the probability of error for band-restricted digital communication are presented. The bounds revolve two values of the complementary error function, the system SNR, the peak value, second moment, and sometimes, the fourth moment of the intersymbol interference. Contrary to other available lower bounds, no parameter searches or infinite series computations are required. The bounds hold when the system "eye" is open and in some cases when the source symbols are correlated.     

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.     

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.     

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.