PROBLEM STATEMENT OF JOINT ANTENNA SELECTION AND PRECODING IN MASSIVE MIMO COMMUNICATION SYSTEMS

Совместный с прекодингом автовыбор антенн на приемной и передающей стороне - одно из перспективных направлений исследований для реализации технологий Multiple Transmission and Reception Points (Multi-TRP, множество точек передачи и приема) в системах со многими передающими и приемными антеннами Massive MIMO (Multiple-Input-Multiple-Output), которые активно развиваются в стандарте 5G. Проанализированы законодательные ограничения, влияющие на применимость технологий Massive MIMO, и специфика реализации разрабатываемого алгоритма в миллиметровомдиапа -зоне длин волн. Рассмотрены алгоритмы формирования матриц автовыбора антенн как на передающей, так и на приемной стороне. Сформулирована строгая математическая постановка задачи для двух критериев работы алгоритма: максимизация взаимной информации и минимизация среднеквадратичной ошибки. Joint precoding and antenna selection both on transmitter and receiver sides is one of the promising research areas for evolving toward the Multiple Transmission and Reception Points (Multi-TRP) concept in Massive MIMO systems. This technology is under active development in the coming 5G 3GPP releases. We analyze legal restrictions for the implementation of 5G Massive MIMO technologies in Russia and the specifics of the implementation of the developed algorithm in the millimeter wavelength range. Algorithms of antenna auto-selection matrices formation on both transmitting and receiving sides are considered. Two criteria are used for joint antenna selection and precoding: maximizing mutual information and minimizing mean square error.

Review of Evidence of Aerosol Transmission of SARS-CoV-2 Particles

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) causes Coronavirus disease (COVID-19) through multiple transmission routes and understanding the mode of transmission is very important for its containment and prevention. Consequently, inadequate attention has been given to the spread of respiratory droplets in indoor conditions under microclimatologic turbulent wind promoted by aerosol from talking (loud), coughing, sneezing, toilet flushing of an isolation room, and resuspension of the settled virus from the surfaces. To this end, this study is presenting an early review of the process and evidence of aerosol transmission of SARS-CoV-2 particles. There are significant results of many studies including those under peer review that support aerosol and airborne transmission which government agencies should consider for reducing the transmission rate.

Miniaturized Wideband Bandpass Filter based on Capacitor-loaded One-eighth Wavelength Coupled Line

A novel miniaturized wideband bandpass filter (BPF) using capacitor-loaded microstrip coupled line is proposed. The capacitors are loaded in parallel and series to the coupled line, which makes the filter just require one one-eighth wavelength coupled line and achieve filtering response with multiple transmission poles (TPs) and transmission zeros (TZs). Compared with the state-of-the-art microstrip wideband BPFs, the proposed filter has the advantages of compact size and simple structure. A prototype centered at 1.47 GHz with the 3-dB fractional bandwidth of 86.5% is demonstrated, which exhibits the compact size of 0.003λ2 g (λg is the guided wavelength at the center frequency) and the minimum insertion loss of 0.37 dB.

A microstrip planar lowpass filter with ultra-wide stopband using hexagonal-shaped resonators

A microstrip planar lowpass filter with ultra-wide stopband up to 40 GHz is presented. The filter is designed based on four types of hexagonal-shaped resonators, producing multiple transmission zeroes and extending the stopband. The high-impedance transmission line is folded to make the circuit more compact and form the coupling gaps between the adjacent resonators. A pair of folded open stubs are added to enhance the cut-off rate. As a result, an ultra-wide stopband with 23rd-harmonic suppression has been attained. A demonstration filter has been designed and fabricated with 3 dB cut-off frequency of 1.70 GHz. The measured results show that the relative stop bandwidth of the low-pass filter (LPF) is 182% with suppression level of 25 dB, covering 1.85–40 GHz. The functional area size of the filter is 21.50 × 21.70 mm, which corresponds to 0.198λ g × 0.200λ g (λ g is the guided wavelength at 3 dB cut-off frequency).

Design of multiple transmission zeros-enabled compact broadband BPFs based on microstrip-to-CPW transition technology

In this paper, we present a miniaturized ultra-wideband (UWB) bandpass filter (BPF) with multiple transmission zeros (TZs), which is based on transition technology of microstrip with short-circuited coplanar waveguide (CPW). The ground plane of the BPF contains a multiple mode resonator (MMR)-based CPW which is capacitively linked through the dielectric to two open-circuited microstrip lines on the top. The MMR is initially designed to allocate its lowest three resonant modes quasi-equally inside the designated UWB spectrum (3.1–10.6 GHz). This is followed by optimization of microstrip lines to provide a good broadband response possessing minimum insertion loss, two TZs at the lower and upper passband edges that improve selectivity and a wide stopband with appreciable attenuation. Later, multiple-folded split ring resonators are coupled to the BPF to inject dual passband TZs. The predicted theory in simulation is verified against measured result and is found to be in good agreement. The prototype covers a substrate area of only 14.6 × 9.2 mm2.