Fading distribution

About: Fading distribution is a research topic. Over the lifetime, 5732 publications have been published within this topic receiving 114193 citations.

Error probability of fast frequency hopping spread spectrum with BFSK modulation in selective Rayleigh and selective Rician fading channels

Abstract: The performance of noncoherent reception in fast frequency hopped spread-spectrum (FFH-SS) communication systems operating through noisy, fading multipath channels is investigated. Systems operating with binary frequency-shift keying (BFSK) modulation and noncoherent demodulation are examined under the assumption of very slow fading. These analyses demonstrate the frequency hopping benefits in selective channels. Expressions are derived for the bit error rate in the context of selective Rayleigh and selective Rician fading channels, as a function of channel and system parameters. >

Buffer and channel adaptive modulation for transmission over fading channels

Abstract: We consider the problem of adaptive modulation for increasing the throughput of transmission over fading channels. In the model, packets arrive at a finite-length buffer according to a Poisson distribution and are mapped into M-ary quadrature amplitude modulated (MQAM) symbols for transmission over a correlated Rayleigh fading channel. We assume that buffer and channel state information are always available at the transmitter. Our objective is to vary the transmit power and the signal constellation size of the modulator according to both the buffer and channel states so that the system throughput is maximized under some average transmit power and bit error rate (BER) constraints. We formulate this optimization problem as a Markov decision process (MDP) and use dynamic programming techniques to obtain the solution. More importantly, we show that, under certain conditions, the optimal transmission rate increases when the channel gain decreases toward the outage threshold - the point below which communication is not possible. This is in contrast to the water-filling structure of the link adaptive policy that achieves capacity on fading channels.

Unified analysis of energy detectors with diversity reception in generalised fading channels

Abstract: In this paper, the authors present a novel moment generating function-based technique to unify the performance evaluation of an average energy detector for detecting unknown deterministic signals over generalised fading environments (including the η-μ, κ-μ, α-μ, K, G and KG generalised fading distributions) with diversity reception. Specifically, the authors exploit a known exponential-type integral representation for the generalised Marcum Q-function Qv (a, b) that is valid for any ratio of a/b but for positive integer order v to greatly simplify the task of finding the statistical expectations over the fading signal-to-noise ratio random variables in the computation of the average detection probability metric. This new approach leads to a very compact and an elegant solution for many practical cases of interest including the independent but non-identically distributed fading statistics and/or arbitrarily correlated diversity branches in maximal-ratio combining, square-law combining and square-law selection diversity receivers. The authors’ numerical results also show that the performance of average energy detector is superior to the classical total energy detector with the increasing number of samples owing to the noise averaging effect. We have also demonstrated the versatility and utility of the proposed analytical framework to investigate the impact of dissimilar mean signal strengths, fading parameters, time-bandwidth product, diversity order and signal combining techniques on the receiver operating characteristics of diversity energy detectors in a myriad of fading environments that had heretofore resisted simple solutions.

Characterization and Modeling of Underwater Acoustic Communications Channels for Frequency-Shift-Keying Signals

Abstract: In a fading channel, bit error rate for frequency-shift-keying keyingsignals is determined predominantly by the envelope amplitude fading statistics of the signal. The narrowband envelope amplitude distributions are measured from the TREX04 data (as a function of frequency) using M-sequence signals centered at 17 kHz with a 5 kHz bandwidth. The results do not fit the Rayleigh, Rician, Nakagami rn-distributions. In contrast, we find that the data are fitted well by a K-distribution. We also analyze the data in terms of long-term and short-term statistics. The long-term and short-term fading statistics are well fitted by the lognormal distribution and Rayleigh distribution respectively, choosing the average time scale to be ~ 0.2 sec. The joint probability distribution function of a lognormal and the Rayleigh distribution is approximately the R-distribution.

Performance of wireless multihop communications systems with cooperative diversity over fading channels

Abstract: We present closed-form bounds for the performance of wireless multihop communications systems with cooperative diversity over Nakagami-m fading channels. The end-to-end signal-to-noise ratio is formulated and upper bounded by using the inequality between harmonic and geometric means of positive random variables. Closed-form expression is derived for the moment-generating function and is used to obtain lower bounds for the average error probability. Numerical results are compared with computer simulations showing the tightness of the proposed bounds. Copyright © 2007 John Wiley & Sons, Ltd.