Showing papers on "Fading distribution published in 1970"
TL;DR: This paper analyzes the performance of adaptive retransmission for improving two-way communication between antenna arrays in a randomly fading environment and shows that a simpler system using phase conjugate retransmissions will also stabilize and maximize the signal-to-noise ratio of an equal gain diversity reception system.
Abstract: We analyze in this paper the performance of adaptive retransmission for improving two-way communication between antenna arrays in a randomly fading environment. For a stationary environment, S. P. Morgan has shown that complex conjugate retransmission reaches a stable state and maximizes the signal-to-noise ratio of a maximal ratio diversity reception system. We show that a simpler system using phase conjugate retransmission will also stabilize and maximize the signal-to-noise ratio of an equal gain diversity reception system. Where the fading is slow in comparison to the system settling-down time, both systems provide a significant improvement in transmission. Subject to Rayleigh fading, we have obtained the average signal strength and its cumulative probability distribution for various combinations of numbers of antennas in the two arrays for each of the above mentioned systems. This information is useful in choosing an optimal division of diversity branches for the two antenna arrays. It is further observed that although the phase conjugate retransmission system is much simpler to implement, its performance is only slightly inferior to the corresponding complex conjugate system.
15 citations
TL;DR: A study is made of the error rate for binary single-path fading channels using photocount detection and the photocount-distribution change caused by fading is proved to be a linear transformation representable by a matrix containing both positive and negative terms.
Abstract: A study is made of the error rate for binary single-path fading channels using photocount detection. First, noiseless channels are examined. The photocount-distribution change caused by fading is proved to be a linear transformation representable by a matrix containing both positive and negative terms. Second, the performance of noisy channels with log-normal fading is discussed by giving the error exponent as a function of noise photocounts, signal-to-noise ratio, and amount of turbulence.
9 citations
TL;DR: The effects of fading on the error-rate performance of a multihop line-of-sight PCM radio system, operated with or without diversity, are theoretically analyzed and a set of approximate formulas for the distribution of error probability has been established.
Abstract: The effects of fading on the error-rate performance of a multihop line-of-sight PCM radio system, operated with or without diversity, are theoretically analyzed. A set of approximate formulas for the distribution of error probability has been established. These formulas can be used to determine the necessary carrier-to-noise power ratio in a noncoherent frequency-shift keying or coherent phase-shift keying system in order to meet the specified error probability and percent outage time.
5 citations
TL;DR: In this paper, the results of line-of-sight propagation measurements at 37 GHz over a 10.0-mile overwater test site are presented, and measurements of the short-term fading statistics, and of the time, space, and frequency diversity parameters are included.
Abstract: The results of line-of-sight propagation measurements at 37 GHz over a 10.0-mile overwater test site are presented. Measurements of the short-term fading statistics, and of the time, space, and frequency diversity parameters are included. Strong negative correlation was observed during both the space and frequency diversity measurements; negative correlation coefficients were as large as -0.8. The diversity improvement obtained was greater than the value expected from correlation calculations, which is attributed to the consistent occurrence of negative correlation in the vicinity of the interference nulls rather than the random occurrence assumed in the calculations. For the optimum case where maximum negative correlation occurs, sufficient diversity improvement is achieved with either space or frequency diversity to permit the elimination of almost the entire fade margin that is needed to overcome the multipath fading associated with reflections from the water surface.
5 citations
01 Feb 1970
TL;DR: A method is introduced by which the statistical properties of the long-term fading of a signal can be found from a section of decibel-scale data.
Abstract: A method is introduced by which the statistical properties of the long-term fading of a signal can be found from a section of decibel-scale data. First the median of a subsection of signal fading in decibels is found directly from the average of its decibel values over each given time interval; then the long-term fading can be plotted. From such fading data, the statistical properties can be found directly and quickly from the measured level-crossing-rate (LCR) curve.
2 citations
TL;DR: In this paper, a transition in performance corresponding to that of a fading target was observed as the sea over which propagation took place became rough, and the radar-detection trials carried out on non-fading targets were carried out.
Abstract: Analysis of recent radar-detection trials carried out on non-fading targets has revealed a transition in performance corresponding to that of a fading target, as the sea over which propagation took place became rough.
1 citations
TL;DR: Measurement techniques for rapidly characterizing frequency selective fading channels are described, specifically applied to FSK modulation and HF channels, and are applicable to other fading media such as troposcatter.
Abstract: This paper describes measurement techniques for rapidly characterizing frequency selective fading channels. The approach used involves estimating each of the parameters describing the transmitted signal and channel disturbances. This includes signal level, noise level, and multipath spread. While specifically applied to FSK modulation and HF channels, the techniques are applicable to other fading media such as troposcatter. The advantages of the proposed techniques are several: the measurement is performed by operating on the transmitted information bits and special test signals or redundancy are not required. Instrumentation is relatively simple and the techniques are applicable to practical communication media. Calculations are provided to determine the measurement time for stated accuracies and confidence levels. Results are obtained for several multipath distributions and as a function of the multipath-to-noise energy ratio.
1 citations
TL;DR: The classical problem is considered of locating a fading sinusoidal signal known to be present in one of several frequency " cells," each of which contains additive white Gaussian noise.
Abstract: The classical problem is considered of locating a fading sinusoidal signal known to be present in one of several frequency " cells," each of which contains additive white Gaussian noise. The signal fading is assumed to follow the popular Rayleigh distribution, but generalizations tions to non-Rayleigh fading are included in terms of the " in" distribution due to Nakagami. The channel observation time is allowed to be either predetermined or variable (corresponding, respectively, to " fixed sample size" and " sequential" reception), and the practically important situation of intermittent signal transmissions is also examined. Results are in the form of optimal and near-optimal receiver structures, and of measures of performance.
1 citations