Showing papers on "Channel state information published in 1984"

Selective fading protection system

Abstract: The fading protection system protects against fading selectively occuring in a specific channel of a plural data transmission system. An equalizer is provided in each channel and adapted to equalize received data. An error correction mechanism is also provided for correcting errors of the received data in at least any one channel. A comparator associated with each channel is provided to deliver a first signal when the level of the received data in the associated channel has been reduced below a predetermined first threshold to indicate a level reduced channel. A controller operates in response to the first signal so as to deliver, as reference data, the correct data, after correction by the error correcting mechanism, to the equalizer provided in the level reduced channel. The controller also effects the supervised learning operation for correcting a coefficient of the equalizer in the level reduced channel so as to reduce the difference between the reference data and the output from the equalizer in the level reduced channel.

ARQ schemes for data transmission in mobile radio systems

Abstract: An important problem in land mobile radio communications is how to provide reliable data communications to the largest number of users. To explore this problem, several existing ARQ protocols are examined which have application to the land mobile radio channel, as well as some new protocol combinations. All protocols are analyzed for several key system performance measures which are verified by experimental means for static as well as fading channels. Finally, a conclusion is reached regarding a new protocol combination which is found to offer significant advantages over all other protocols explored.

Block Error Performance of Noncoherent FSK Modulation on Rayleigh Fading Channels

Abstract: In this paper, the calculation of the probability P_{f}(M, N) of more than M bit errors in a block of N bits transmitted over a Rayleigh fading channel using noncoherent frequency shift keying is considered. Accurate approximations to P_{f}(M, N) are derived under the assumption of very slow fading. Approximations are also given when a selection diversity system is used. An application of the results to the calculation of the block error rate when the assumption of very slow fading is relaxed is then discussed.

Effects of Nonzero-Centroid and Skewness of Fading Spectrum on Incoherent FSK and DPSK Error Probabilities

Abstract: The effects of nonzero-centroid and skewness of a fading spectrum are shown to influence the binary error probabilities of incoherent FSK and differentially coherent phase-reversal (DPSK) matched-filter receivers. It is also shown that for incoherent FSK, the skewness or nonzero centroid in the fading spectrum causes different error probabilities for binary signals, resulting in a binary asymmetric channel. The difference in error probabilities for binary signals can be used as a criterion for aligning the transmitter and receiver antennas coupled through a fading channel.

A Computer Simulation of the Effect of Fading on a Quasi-Synchronous Sideband Diversity AM Mobile Radio Scheme

Abstract: In this contribution, a software multipath fading simulation package (previously applied to the statistical analysis of the fading statistics of single transmitter schemes for three very different mobile radio environments) is used to analyze the performance of a quasi-synchronous, multitransmitter, amplitude modulated sideband diversity area coverage system. By conducting field trials in an area known to obey Rayleigh fading statistics, it has been possible to compare the simulated statistical results to those obtained theoretically and experimentally, and to show that good agreement exists. The fading simulator is capable of being extended to other types of multitransmitter radio scheme employing different forms of modulation.

Statistical Analysis of Digital Phase-Locked Loops Fading Channiels

Abstract: Statistical analyses of zero-crossing sampling first- and second order digital phase-locked loops in fading channls (DPLFC) are presented. A DPLFC is defined as one where the incoming signal is not only corrupted by additive Gaussian noise channel (AGN) but also by a fading communication channel. The three fading channels considered are the log-normal, Rayleigh, and Rician channels. The performance degradation of the DPLFC operation is characterized by the steady-state phase-error process probability density function and phase-error variance. Approximate analytic expressions for the phase-error statistics of a first-order DPLFC for both phase-step and frequency-step inputs are obtained by solving the Chapman-Kolmogorov equation associated with the phase-error process. The second-order DPLFC is analyzed for a frequency-step input. Numerical and simulation results are provided confirming the analyses presented for the three fading channels considered.