Авіаційно-космічна техніка та технологія (Aug 2018)
TERAHERTZ TECHNOLOGIES IN TELECOMMUNICATION SYSTEMS. PART 1. JUSTIFICATION OF THE FREQUENCY RANGE, DESIGN OF FUNCTIONAL NODES OF TERAHERTZ RANGE TELECOMMUNICATION SYSTEMS
Abstract
The article presented results of researches conducted by the team of authors devoted to the possibilities of creation for the first time in Ukraine the real prerequisites for solving the fundamental problem of constructing digital telecommunication systems with the use of terahertz technologies. The necessity of transition to the use of the terahertz frequency range substantiated during the deployment of future telecommunication systems of ultra-high bandwidth. The analysis of characteristics of the path of signal propagation and determination of signal losses in conditions of operation of the radio relay system in the terahertz frequency range is carried out. The conducted analysis has shown that in the frequency range of 30-300 GHz, the most important types of fading that should consider during the design are fading due to the easing of the signal by hydrometeors and fading due to the absorption of the radio signal in gases, fading due to the influence of the antenna pattern. It determined that the work of the radio relay lines in the terahertz range allows practically not to take into consideration the refraction and interference of electromagnetic waves reflected from interference in the zone of radio signal propagation, which arises especially in conditions of dense urban development. This is due primarily to the fact that the terahertz waves have a low ability to "bend" the noise, and secondly, at the current frequency of 30 to 300 Hz apply at relatively small distances (up to 5 km), which allows for avoiding spatial planning interference to the zone of direct visibility of antennas and the first Fresnel zone. It considered the main factors that lead to the emergence of fading in radio relay communication lines. It is shown that in the terahertz range the greatest influence on the energy potential of the radio-relay lines is attenuating in hydro meteors and gases. The terahertz frequency range areas allocated that is most suitable for application in radio relay communication lines. The principles of formation of signal-code construction considered methods and new technical solutions for choosing the type of signal construction proposed in order to achieve the best bandwidth and performance in the channel of communication of a wireless gigabit system of transmission in the terahertz range. The physical simulation of the ultra high-speed shaper based on multifrequency multiplexing of the modulated OFDM digital streams has been carried out, bench tests and optimization have been carried out to achieve the maximum bandwidth of the digital data transmission channel in the Ethernet format using the developed software. The developed software and hardware allowed for the first time to reach the overall channel speed with a full duplex up to 1.2 Gb / s. On the basis of the generalization of the results of theoretical research and experimental work, the analysis of the existing radio relay element base, the design of the main nodes of the receiving and transmitting parts of a telecommunication system with a gigabit throughput in the frequency range 130-134 GHz, the structural scheme of the transmitting and receiving system of the system is developed: frequency mixer with subharmonic pumping, the heterodyne, which uses a highly stable reference quartz oscillator with a subsequent chain of multiplication and under power stage, bandpass filter using a thin metal plate in the E-plane of the waveguide channel 1.6x0.8 mm, horn antenna. It is presented the results of experimental studies of the main nodes of the receiving and transmitting parts of a telecommunication system with a gigabit throughput in the frequency range 130-134 GHz. Scientific novelty of the work consists in generalization and development of the theory of distribution, generation and measurement of terahertz signals, in the development of the method of multiple frequency multiplexing and generation of modulated OFDM digital streams in the terahertz frequency range and the development of the principles of functional design of the receiving and transmitting parts of a telecommunication system with a gigabit throughput in terahertz frequency range
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