Impact of Pointing Errors on the Performances of Double Rician FSO Channels

In this paper we will propose new analytically traceable probability density function (PDF) model for free space optics (FSO) turbulence, obtained as a generalization of double Ricean turbulence model, that encompasses both large-scale and small-scale turbulence eddy effects along by taking into account performance decreasing influence of misalignment introduced through boresight pointing error model. Consequently, after delivering the closed-form expressions for the newly introduced double FSO model, we obtain the analytical expressions for the bit error rate (BER) performance for the Double Rician distribution affected by misalignment. Numerical results will show the impact of system parameters on FSO link performance and we will provide full performance analysis. © 2021.

Estimation of signal reception probability characteristics using models of fading transionosphere channels

Statistical models of narrow-band transionosphere channels, which determine the occurrence of signal fading due to random temporal and spatial fluctuations of the electron density of ionospheric irregularities, are considered. Fading models are based on the use of empirical relationships with respect to the distribution density of the amplitude of the signals at the output of the transionosphere channel as a random process. The parameters of empirical distribution densities (lognormal distribution, m-Nakagami distribution, Rician distribution) are related to the scintillation coefficient of signal fading. Using the considered models of signal fading, a technique is presented for estimating the probability of erroneous reception of digital signals with phase shift keying during reception. Using this technique, estimates of energy losses with respect to propagation in free space were made, reaching 0.001 for a scintillation coefficient value of 0.5 to 3 dB for signals with 2- and 4-phase shift keying.

A Modification of Rician Distribution for SAR Image Modelling

This paper presents a novel statistical model i.e. the Laplace-Rician distribution, for the characterisation of synthetic aperture radar (SAR) images. Since accurate statistical models lead to better results in applications such as target tracking, classification, or despeckling, characterising SAR images of various scenes including urban, sea surface, or agricultural, is essential. The proposed Laplace-Rician model is investigated for SAR images of several frequency bands and various scenes in comparison to state-of-the-art statistical models that include K, Weibull, and Lognormal. The results demonstrate the superior performance and flexibility of the proposed model for all frequency bands and scenes.

Small-Scale Fading Characteristics in Cellular Networks in Ghana

Fading is the most observed and frustrating problem in transmitting and receiving radio signals. A Study in correlation properties of fading helps to design proper communication systems that are robust to it. In this work, received power signal was obtained by drive-test technique. The analysis was determined using distribution fitting tool in Matlab software 7.5.0 (R2007b). The following fading distributions were used, Rayleigh, Rician, Nakagami-m, Lognormal and Weibull. Weibull fading distribution was found to give the best description of fading experienced in Ghana.On the other hand, Rician distribution, Nakagami-m distribution and lognormal distribution have less agreement with the measured data while Rayleigh fading distribution has much less agreement with measured data. The obtained mean scale parameter and the mean shape parameter in the Weibull distribution for the environment considered were 133.76 and 15.93, respectively. Furthermore, the path loss exponents in the near and far fields were also calculated; and the standard deviation of shadowing fell in the range of 4.368dB to 6.180dB.