Showing papers on "Fading distribution published in 1978"

Error Probability Characteristics for CPSK Signal Through m-Distributed Fading Channel

Abstract: The average error probabilities and outage rates of error probability for the M -phase CPSK signal through the Nakagami's m -distributed fading channel are exactly evaluated both for nondiversity reception and for diversity reception. The probability density functions of the composite phase of fading signal and noise and those of the diversity-combined signal envelopes are newly derived in this paper. The results are generally obtained including the digital phase modulation component, the fading figure as a measure of fading depth, the average carrier-to-noise power ratio, the power correlation coefficient between two diversity branches, etc. The diversity improvements are also verified. Additionally some useful approximate formulas are briefly shown. This study will add a newly widened view to the considerations of system performances and designs for digital radio communications via fading channels.

First-order statistics of a non-Rayleigh fading signal and its detection

Abstract: The first-order statistics of the vecter sum of a complex Gaussian variable and N complex exponentials with constant amplitudes but random independent phases are used to model a non-Rayleigh fading signal. Envelope detection, optimal for detecting Rayleigh (N = 0) and Rician (N = 1) signals, is also shown to be optimal for the considered non-Rayleigh signals in additive white Gaussian noise. However, the signal-to-noise ratio required to detect the latter signal for N = 2 may be substantially higher than for the former cases. Possible applications of this fading model to studies of multipath fading, non-Rayleigh sea echoes, microwave or laser radar detection and tracking are discussed.

Error rate predictions and measurements in the mobile radio data channel

Abstract: A method of predicting the loss in error performance in mobile radio data transmission is given in which the variation in local mean signal level (shadowing) is included as well as fading. Also, the density function of the received signal envelope is found for the case of fading and shadowing. Field measurements are reported of error rates at VHF and UHF due to vehicle ignition noise, and the distribution of errors is plotted.

A Multipath Fading Channel Model for Terrestrial Digital Radio Systems

Abstract: The frequency transfer function of a multipath fading channel is examined in terms of its effects on digital radio signals. The transfer function is expanded into a power series about the channel center frequency and the coefficients are related to the multipath structure. It is then shown that, in the channelized common carrier bands below 15 GHz, the first two (complex) terms of the power series are usually sufficient for characterizing multipath effects. This demonstration is based on a mean-square error-of-fit measure which is applied to the multipath fading response and evaluated under some worst-case assumptions.

A Receiver with Memory for Fading Channels

Abstract: In this paper, an adaptive receiver with memory for fading communication channels is considered. The receiver consists of an estimator and a detector. The estimator is a finite-memory MMSE estimator with decision-feedback which minimizes the probability of error of the receiver. Asymptotic approximations are employed to derive an adaptive decision role based on the estimate. An example is presented where the receiver with memory is shown to perform better than an optimum receiver without memory.

Noncoherent Detection of FSK Signals in the Presence of Multipath Fading

Abstract: The performance of a noncoherent frequency-shift keyed (FSK) system is analyzed in the presence of multipath fading by using a sinusoidal series expansion technique for the representation of a bandlimited Gasussian process. The probability of error is calculated as a function of the system parameter BT , signal-to-noise ratio, fading bandwidth and direct to reflected signal power ratio.

Mean power of the components of a Rice fading signal determined from measurements

Abstract: A method is provided for estimating the mean power of each of the two components of a Rice fading signal, given measurements of the mean and standard deviation of the total signal power.

Application of forward-error correction to a Rayleigh fading h.f. communication channel

Abstract: The performance is assessed of a Rayleigh fading hf communication channel which transmits binary data using a selection of forward-error correction systems The criteria adopted are the probabilities of no character error, and not more than one character error in a message containing a specified number of characters, each character consisting of five information bits The basic standards for comparison are taken to be the start/stop telegraphy mode of transmission and the synchronous transmission of pure information The error-correction systems studied are tor, autospec and BCH(31, 21), all employing block coding Where interleaving is applicable the improvement obtained is assessed The advantages of employing space diversity are also assessed The case of a constant signal is included for completeness It is assumed that the probability of an element error is related to channel signal/noise by an exponential modem curve The calculations are part probabilistic, part simulation Errors and efficiency of the method are discussed

Fading at 9.6 GHz on an experimentally simulated aircraft-to-ground path

Abstract: This report describes an experimental study of fading at 9.6 GHz on a fixed slanted line-of-sight path simulating aircraft-to-ground propagation conditions. Recordings of signal fading were made over about one year. The data were analyzed to provide a statistical description of the fading, and to compare some of these statistics with those obtained elsewhere under different climatic and terrain conditions. The results include the probabilities of occurrence of fading rates and fade durations at several signal levels below the hourly median level. The extent to which fading behavior depends on time-of-day and time-of-year was investigated, along with the correlation of hourly average fade duration and hourly fading rate.

The Fadeogram, A Sonogram-Like Display of the Time-Varying Frequency Response of HF-SSB Radio Channels

Abstract: A method is presented for displaying the time-varying transfer characteristic of communication channels, and is illustrated by showing in detail the behavior of an HF-SSB radio channel during one minute periods, under the various fading characteristics classified by USAEL. It is also demonstrated how this method aided study of the causes of errors in data received by digital modems.

Simulation of rayleigh fading by digital generation of amplitude and phrase

Abstract: Formulae are given for the spectrum and the distribution of the summed output of n weighted stages of a shift-register whose input is random. The formulae are applied to the discrete-time simulation of the independent noise components N x and N y of Rayleigh fading. They are next applied to processes N r and N θ for the simulation of amplitude and phase, following a mathematical study of the processes required.

The determination of sky-wave received signal level

Abstract: HF sky wave signal strengths measured at a number of frequencies over short- and medium-range paths (100-2000 km) are compared with two prediction methods. The statistical behavior of the rapid fluctuations of the received signal level are analyzed, and the diurnal dependence of the fading depth is found qualitatively.