Showing papers on "Channel state information 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.

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.

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.

High-reliability data transmission to mobile vehicles

Abstract: The design for an adaptive-rate data transmission system providing very reliable two-way data transmission over a fading mobile channel is outlined and measurements are presented. A single u.h.f. or v.h.f. carrier is required. Operation with practical fading has been tested using a recording of variations in mobile-channel gain in conjunction with a hardware simulation of the system. The tests show that an error probability of 10−10 can readily be achieved. For operation in 12.5 kHz bandwidth, four-phase keying at 10 kbauds is proposed. In this case the system will provide a mean data rate in each direction of 1.8 kbit/s with the mean power of the fading signal 7 dB above the receiver noise. With increasing received power the mean data rate in each direction tends to 4.8 kbit/s. These rates can be doubled by interleaving an identical scheme operating on a second carrier frequency.