A.A. Ilyukhin - Ph. D. (Eng.), Associate Professor, Academy of Federal Security Guard Service of the Russian Federation, Oryol. E-mail: ilyukhin.orel@mail.ru A.V. Vdovin - The Academy of Federal Security Guard Service of the Russian Federation, Oryol. E-mail: veron-amel@yandex.ru

To realize extremely large throughput of transponders in conditions of satellite capacity\'s deficiency, domestic satellite communication operators FGUP \"Space Communication\", OAO \"Gazprom Space Systems\" are expanding satellite grouping in Ku and KA bands. However, Ku band satellite channel is greatly subjected to atmospheric effects\' influence (hydrometeors, troposphere scintillations) resulting in packets losses when transmitted in consequence of signal-to-noise ratio (SNR) decrease at the input of satellite demodulators. Based on the results of statistical research of long-term median attenuation of Ku bands radio signal, redundant resource is inserted into energy budget of designed satellite channel for radio signal attenuation compensation for the worst propagation conditions. Usage of controlling schemes by transmission level and adaptive modulation and noise-immune coding allows to partly decrease energy redundancy or to increase satellite channels\' capacity in conditions of atmospheric disturbances, but demands to perform procedure of signal-to-noise ratio (SNR) measurements and controlling commands transmission in the reverse channel. Potential efficiency of the given schemes\' operation at satellite channel\'s designing stage in atmospheric disturbances dynamics can be evaluated according to modeling data of sampling SNR allocations obtained with respect to experimental measurements results. Satellite channel noise immunity state is estimated by ratio of signal energy to spectral density of noise power averaged on the reference symbols (pilot symbols) sequence. Ratio evaluation is formed on basis of processing complex amplitude coefficients measured at the output of satellite demodulator\'s cophasal and quadrature branches and reference pilot symbols sequence according to maximal likelihood method. Multiple experimental measurements performed in Ku band confirm hypotheses about standard and logarithmically standard laws of allocation density and well-known spectrally correlated properties of radio signal attenuation when propagated in \"clear sky\" conditions (under the influence of troposphere scintillations) and precipitation effect (rain). Generator scheme of sample SNR values based on two processing paths: linear and nonlinear conversion of discrete random sequence is proposed. Filtering temporal series of white Gaussian noise\'s source is carried out by exponential smoothing filter on basis of specified recurrent relation. Consequently, by scaling and combining temporal series in processing branches, as well as taking into consideration SNR obtained by calculating energy budget of designed satellite channel nonregistering disturbed atmosphere effect, temporal series that is adequate to experimental statistical data about spectral characteristics, magnitude and duration of signal attenuation is generated at the shaping filter output. Inaccuracies of modeling statistical characteristics in terms of mathematical expectation and attenuation dispersion due to atmospheric effects amount no more 2 - 3%. Model validity is confirmed by adequate obtained experimental data results. Application of developed model is proposed in receiving predictive SNR estimations for radio signal attenuation compensation to increase frequency or energy efficiency of satellite channel.

 

1. Anpilogov V.R., Afonin A.A. Zatukhanie v sputnikovykh kanalakh Ku- i Ka-diapazonov // Sputnikovaja svjaz i veshhanie. 2010. 75 s.
2. van de KampM.Statistical Analysis of Rain Fade Slope // IEEE Trans. Ant. and Propagat. 2003. V. 51. №8. P. 1750-1759,
3. Lacoste F., Bousquet M., Castanet L., Cornet F., Lemorton J. Improvement of the ONERA-CNES rain attenuation time series synthesiser and validation of the dynamic characteristics of the generated fade events // Space Communications 2005. № 20. R.45-59.
4. Cheffena M., Amaya C. Prediction Model of Fade Duration Statistics for Satellite Links between 10-50 GHz  // IEEE Antennas and Wireless Propagation Letters. 2008. V. 7. P. 260-263.
5. Wang Kun, Wu Si-liang, Zhu Sheng-yu Research on SNR Estimation of Signals in Galileo SAR System // International Conference on Computer and Electrical Engineering. 2010. P. 16-22.
6. Artemov M.L., Borisov S.G., Slichenko M.P. KHarakteristiki maksimalno pravdopodobnogo obnaruzhenija radiosignalov monoimpulsnymi obnaruzhiteljami-pelengatorami s antennojj sistemojj proizvolnojj konfiguracii // Radiotekhnika. 2014. №11(126). S. 11-14.
7. Dmitriev I.S., Slichenko M.P. Maksimalno pravdopodobnoe obnaruzhenie i ocenivanie napravlenija prikhoda i amplitudy naprjazhennosti radiovolny s pomoshhju mnogokanalnogo radiopelengatora s antennojj sistemojj proizvolnojj konfiguracii // Antenny. 2011. №5(168). S. 59-64.
8. JArushkina N.G., Afanaseva T.V., Romanov A.A., Timina I.A.Izvlechenie znanijj o zavisimostjakh vremennykh rjadov dlja zadach prognozirovanija // Radiotekhnika. 2014. № 7(146). S. 141-146.