Maximum electric field estimation in the vicinity of 5G base stations before their start-up

Introduction/purpose: This paper presents initial development of the procedure for electric field estimation in the vicinity of 5G base stations. Methods: The procedure allows determination of future radiation levels before traffic is established over applied antenna systems on the basis of measured values of electric field levels caused by the signal forming Synchronization Signal Block. It is possible to perform necessary calculations for a very accurate estimation even if some important parameters of the radiation characteristics (such as the frequency span between the frequency carriers on the radio interface) are not a priori known. In this way, communication with mobile system operators before measurement is significantly simplified because operators do not need to know system technical details. Results: The developed formula for electric field estimation is verified comparing the calculated values by its implementation to the practical results obtained by intensive measurements on a great number of 5G base stations in a highly developed country. The formula gives a pessimistic result, i.e. a higher electric field level than it is obtained by all such performed measurements. Conclusion: This estimation allows mobile system operators to predict whether the electromagnetic field around base stations could be dangerous for human health when systems come to full operation while considering national and international recommendations dealing with radiation levels

DOHERTY AMPLIFIER LINEARIZATION BY DIGITAL INJECTION METHODS

Verification of two linearization methods, applied on asymmetrical two-way microstrip Doherty amplifier in experiment and on symmetrical two-way Doherty amplifier in simulation, is performed in this paper. The laboratory set-ups are formed to generate the baseband nonlinear linearization signals of the second-order. After being tuned in magnitude and phase in the digital domain the linearization signals modulate the second harmonics of fundamental carrier. In the first method, adequately processed signals are then inserted at the input and output of the main Doherty amplifier transistor, whereas in the second method, they are injected at the outputs of the Doherty main and auxiliary amplifier transistors. The experimental results are obtained for 64QAM digitally modulated signals. As a proof of concept, the linearization methods are also verified in simulation, for Doherty amplifier designed to work in 5G band below 6 GHz, utilizing 20 MHz LTE signal

Graphene-based waveguide resonators for submillimeter-wave applications

Utilization of graphene covered waveguide inserts to form tunable waveguide resonators is theoretically explained and rigorously investigated by means of full-wave numerical electromagnetic simulations. Instead of using graphene-based switching elements, the concept we propose incorporates graphene sheets as parts of a resonator. Electrostatic tuning of the graphene surface conductivity leads to changes in the electromagnetic field boundary conditions at the resonator edges and surfaces, thus producing an effect similar to varying the electrical length of a resonator. The presented outline of the theoretical background serves to give phenomenological insight into the resonator behavior, but it can also be used to develop customized software tools for design and optimization of graphene-based resonators and filters. Due to the linear dependence of the imaginary part of the graphene surface impedance on frequency, the proposed concept was expected to become effective for frequencies above 100 GHz, which is confirmed by the numerical simulations. A frequency range from 100 GHz up to 1100 GHz, where the rectangular waveguides are used, is considered. Simple, all-graphene-based resonators are analyzed first, to assess the achievable tunability and to check the performance throughout the considered frequency range. Graphene–metal combined waveguide resonators are proposed in order to preserve the excellent quality factors typical for the type of waveguide discontinuities used. Dependence of resonator properties on key design parameters is studied in detail. Dependence of resonator properties throughout the frequency range of interest is studied using eight different waveguide sections appropriate for different frequency intervals. Proposed resonators are aimed at applications in the submillimeter-wave spectral region, serving as the compact tunable components for the design of bandpass filters and other devices

An Adaptive Fuzzy Logic System for the Compensation of Nonlinear Distortion in Wireless Power Amplifiers

Computational intelligent systems are becoming an increasingly attractive solution for power amplifier (PA) behavioural modelling, due to their excellent approximation capability. This paper utilizes an adaptive fuzzy logic system (AFLS) for the modelling of the highly nonlinear MIMIX CFH2162-P3 PA. Moreover, PA’s inverse model based also on AFLS has been developed in order to act as a pre-distorter unit. Driving an LTE 1.4 MHz 64 QAM signal at 880 MHz as centre frequency at PA’s input, very good modelling performance was achieved, for both PA’s forward and inverse dynamics. A comparative study of AFLS and neural networks (NN) has been carried out to establish AFLS as an effective, robust, and easy-to-implement baseband model, which is suitable for inverse modelling of PAs and capable to be used as an effective digital pre-distorter. Pre-distortion system based on AFLS, achieved distortion suppression of 84.2%, compared to the 48.4% gained using the NN-based equivalent schem

Contribution to Evaluation of Nonlinear Distortion in 5G IoT Subsystems

An evaluation of nonlinear distortion in mmWave 5G IoT wireless transmitters is investigated in this paper. A Filter Bank Multi-Carrier (FBMC) waveform for mmWave 5G IoT wireless transmitters is used. Simulated output power spectra of the MMIC power amplifier (HMMC 5026) for 5G FBMC 5 MHz waveform and different input power levels such as -10 dBm, 0 dBm, 10 dBm and 30 dBm are presented. Simulated output power spectra of the MMIC power amplifier for 5 MHz 5G FBMC signals at different input power levels are illustrated

Network Service Assurance and Telemetry optimisation using Heuristics

This paper identifies possible solution to reduce amount data retrieved for purpose of network monitoring, while retaining the quality of information. Legacy methods used for network service monitoring data using and data retrieved by use of synthetic tests are usually decoupled – describing different contexts. As a result, there is too many monitored operational parameters on monitored devices and consequently too much measurement data exported from network service probes. Novel approach is suggested to perform heuristic analysis of the network service configuration and decomposition of collected data at the network edge. Objective is that amount of collected data can be reduced while at the same time quality of the presented information can be improved by providing clear correlation between network service and telemetry data

Doherty amplifier linearization by digital injection methods

Verification of two linearization methods, applied on asymmetrical two-way microstrip Doherty amplifier in experiment and on symmetrical two-way Doherty amplifier in simulation, is performed in this paper. The laboratory set-ups are formed to generate the baseband nonlinear linearization signals of the second-order. After being tuned in magnitude and phase in the digital domain the linearization signals modulate the second harmonics of fundamental carrier. In the first method, adequately processed signals are then inserted at the input and output of the main Doherty amplifier transistor, whereas in the second method, they are injected at the outputs of the Doherty main and auxiliary amplifier transistors. The experimental results are obtained for 64QAM digitally modulated signals. As a proof of concept, the linearization methods are also verified in simulation, for Doherty amplifier designed to work in 5G band below 6 GHz, utilizing 20 MHz LTE signal