Lithuanian Journal of Physics article / Lietuvos fizikos žurnalo straipsnis

WIRELESS COMMUNICATIONS BEYOND 5G: UNCERTAINTIES OF TERAHERTZ WAVE ATTENUATION DUE TO RAIN
Milda Tamošiūnaitė^a, Vincas Tamošiūnas^a,b, and Gintaras Valušis^a
^aCenter for Physical Sciences and Technology, Saulėtekio 3, 10257 Vilnius, Lithuania
^bInstitute of Photonics and Nanotechnology, Vilnius University, Saulėtekio 3, 10257 Vilnius, Lithuania
E-mail: milda.tamosiunaite@ftmc.lt
Received 17 April 2018; revised 15 May 2018; accepted 21 June 2018

Statistical peculiarities of terahertz (THz) wave attenuation in heavy rain conditions are evaluated. The expected extreme densification of the infrastructure and the application of highly directional beams of 5th generation (5G) and beyond 5G (B5G) wireless networks were taken into account. Calculations were performed emulating both drop size distributions of the real rain and the laboratory-controlled rain described in literature. Simulation results revealed that absorbance fluctuations of more than one percent would occur if THz waves and raindrops interact within the 100 m³ volume. For much smaller volumes, short distances and narrow beams used for experiments with the laboratory-controlled rain, absorbance uncertainties could exceed the average absorbance value. A comparison of the simulation results at fixed average absorbance revealed that slightly lower uncertainties were expected in the case of a single raindrop size when compared to the Weibull distribution approximating the real rain. Nevertheless, in both cases the predicted deviations were substantially smaller than observed in the previously published experimental results. This fact predicts a new future application possibility for such laboratory-based experiments – they can be employed to predict the performance of wireless THz data transmission links when the resilience margin is required. Since much of the existing industrial test equipment is not designed to carry out calibrated over-the-air measurements of 5G/B5G wireless networks, such experiments can be employed to primarily predict the performance of data transmission links.

Keywords: terahertz, rain, attenuation, wireless communications, Mie scattering
PACS: 92.40.Ea, 84.40.Ua, 42.25.Fx

5G/B5G BEVIELIS RYŠYS: TERAHERCINIŲ BANGŲ SILPNINIMO DĖL LIETAUS NEAPIBRĖŽTUMAI
Milda Tamošiūnaitė^a, Vincas Tamošiūnas^a,b, Gintaras Valušis^a

^aVMTI Fizinių ir technologijos mokslų centras, Vilnius, Lietuva
^bVilniaus universitetas, Vilnius, Lietuva

Šiame darbe pritaikant statistinius metodus nagrinėjami terahercinių (THz) bangų silpninimo ypatumai stipraus lietaus sąlygomis. Modeliuojant buvo atsižvelgta į pagrindinius 5-os kartos (5G/B5G) bevielių tinklų veikimo principus: infrastruktūros tankėjimą ir signalo sklidimo kryptingumą. Skaičiavimai atlikti remiantis literatūroje aprašytais faktinio ir laboratorijoje kontroliuojamo lietaus lašų dydžio pasiskirstymais. Modeliavimo rezultatai parodė, kad THz bangai ir lietaus lašams sąveikaujant 100 m³ tūryje pasireikštų daugiau kaip 1 % sugerties svyravimai. Laboratorijoje kontroliuojamo lietaus atveju, esant trumpiems atstumams ir siauram spinduliui, šie svyravimai gali viršyti vidutinę sugerties vertę eile. Modeliavimo rezultatų palyginimas fiksuotos vidutinės sugerties atveju atskleidė, kad eksperimentuose su vienodo dydžio lašais yra tikėtini šiek tiek mažesni sugerties koeficiento nuokrypiai, palyginti su tikru lietumi, aprašomu Weibull’o funkcijos pasiskirstymu. Nepaisant to, abiem atvejais prognozuojami svyravimai buvo gerokai mažesni, nei buvo stebimi anksčiau skelbtuose eksperimentų rezultatuose. Tai patvirtina tokių eksperimentų taikymo galimybę. Kadangi dauguma pramonėje naudojamos įrangos nėra suprojektuota atlikti kalibruotus 5G/B5G belaidžių tinklų matavimus bangai sklindant oru, tokie eksperimentai gali būti naudojami siekiant prognozuoti tikėtiną duomenų perdavimo našumą.

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