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Frequency sharing problems may occur between neighboring networks when multiple operators build 5G private networks within a specific region. The interference between time division duplex (TDD) 5G private networks depends on various factors, such as frequency channels, synchronization, and building entry loss (BEL). In this study, we propose separation distances at which two 5G private networks in close proximity can coexist. The amount of interference according to the separation distance between the two 5G private networks was simulated by the Monte Carlo (MC) method. When the two networks operated in an outdoor environment and had different channels, there was a minimum interference effect even if the cell radii of the two networks overlap. However, the separation distance between networks using the same channel was simulated to be approximately 500 m. The TDD synchronization of two networks using the same channel reduced the separation distance to approximately 100 m. The additional radio wave attenuation by the BEL reduced the amount of interference, allowing frequency coexistence between networks even within the cell radii.

In this paper, the calibration of a fully-switched MIMO channel sounder with internal crosstalk is considered. A system model is proposed, taking into account the effect of the internal crosstalk in the transmitter and receiver response matrices. A least-square system identification problem is then formulated to find the estimates of the response matrices from a set of back-to-back measurement data. It is shown that the problem can be converted to rank-one approximation problems in the frequency domain. In addition, a channel estimation method is proposed for calibrating over-the-air measurement data by using the identified response matrices of the sounder. Experimental and simulation results show that the proposed system modeling and identification procedure compensate for the internal crosstalk of the sounder much better than the conventional approach that ignores the crosstalk.

This white paper describes the results of a channel measurement campaign for 5.9GHz V2V channel characteristics on expressway environment for the case of driving simultaneously in opposite directions at a speed of 100 km/h, respectively. We describe the measurements and results of delay spread and K factor, also in order to fully reflect the environment where the measurement was made, we additionally propose a stationary distance to that satisfies the WSS (Wide Sense Stationary) condition in the expressway environment at 5.9 GHz.This measurement will be useful for future research about Vehicle-to-Vehicle (V2V) wireless communications formed based on proposing stationary distance and new channel characteristics

We built a system for single-input multiple-output (SIMO) wireless channel sounding at 5.9GHz center frequency. Then we measured continuous channel impulse response of wireless channel at Yeoju Expressway # 45 environment where vehicles are traveling more than 100km/h (27.8 m/s) for characteristics of stationary distance. Unlike high speed train environments, high Doppler shifts can occur due to many neighboring vehicles as moving scatterers in a variety of directions and in a short time. Radio links to vehicles can be direct or relay depending on whether the antenna is inside the vehicle or on top of the vehicle, respectively. The measurements were performed to estimate the distance over which the channel can be considered stationary and to ensure the validity of channel parameters at an expressway in Yeoju, Korea using a channel sounder with 100MHz bandwidth at 5.9GHz.This measurement will be useful for future research about Vehicle-to-everything (V2X) wireless communications by proposing stationary distance for a new channel link model that has not been reported before.

The antenna height of the terminals in vehicular communication is low, and the propagation characteristics are affected by surrounding buildings. Most modern urban area has many artificial buildings, including underpasses and over passes, which affect propagation characteristics. We provide the measurement values for propagation characteristics in the 5.89 GHz band for an underpass area located in Daejeon, Korea. We divide the radio wave propagation area around the underpass into three different sections: down way section, underpass section, and up way section. The path loss exponent value and the rms delay spread value of the underpass path was highly measured than that of the roadway path. The floor and walls of underpass block the radio wave propagation, increasing path loss and multipath delay spread.

A study on temperature stabilization effect of the immersion liquid in a 3-6 GHz microwave tomography (MT) system for medical diagnosis is presented. The designed temperature control device unit is applied in the MT system for the analysis of the temperature impact. This control unit with an advanced control method is required to precisely maintain the temperature of the immersion liquid for obtaining stable measurement data. If the temperature of the liquid is maintained ideally, the peak to peak deviation of the measured amplitude and phase are very small within approximately 0.18 dB and 1.3 degree over the entire frequency range. The temperature variation of the liquid is a key factor for high spatial resolution to detect small tumors. The detailed results are presented and discussed. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:461–464, 2016

This paper presents an experimental measurement system for 3?6 GHz microwave tomography (MT) of the breast. The measurement system is constructed as a minimal test bed to verify key components such as the sensing antennas, radio frequency (RF) transceiver, sensing mechanism, and image reconstruction method for our advanced MT system detecting breast cancer at an early stage. The test bed has eight RF channels operating at 3 to 6 GHz for high spatial resolution and a two-axis scanning mechanism for three-dimensional measurement. The measurement results from the test bed are shown and discussed.

The early detection of breast cancer is very important. The final goal of this study is to develop an inexpensive portable device for simply detecting the existence of breast cancer using microwaves. In this study, we proposed a detection algorithm and the system configuration of such a device. The feasibility of the proposed method was investigated by numerical simulation and actual measurement. A prototype sensing module was fabricated, and the measurement results for tumor phantoms were presented. The measurement results showed that the prototype sensing module worked well, and the simulation results revealed that the detection rate of the device could be about 60% for a 4 mm tumor and almost 100% for a 6 mm tumor. The proposed device can be used for the self-diagnosis of breast cancer. Further study is required to reduce the size of the sensing module.

This article presents the image reconstruction results of measurement data from a preliminary test using the first-developed precision microwave tomography (MT) system operating at 3–6 GHz for medical diagnosis. A simple phantom is used in the MT system to verify the data validation. The measurement dataset has very different patterns owing to the significant contrast of dielectric properties according to the existence of a phantom in the sensing area of the illumination tank at microwave frequencies. Thus, it is possible to obtain the image reconstruction from this measurement data. The detailed results are presented and discussed. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2445–2448, 2015

Microwave imaging (MI) is one of the most promising and attractive new techniques for earlier breast cancer detection. Microwave tomography (MT) realizes configuration of a multistatic multiple-input multiple-output system and reconstructs dielectric properties of the breast by solving a nonlinear inversion scattering problem. In this paper, we describe ETRI 3D MT system with 3D MI reconstruction program and demonstrate its robustness through some examples of the image reconstruction.

As a supplement to X-ray mammography, microwave imaging is a new and promising technique for breast cancer detection. Through solving the nonlinear inverse scattering problem, microwave tomography (MT) creates images from measured signals using antennas. In this paper, we describe a developed MT system and an iterative Gauss-Newton algorithm. At each iteration, this algorithm determines the updated values by solving the set of normal equations using Tikhonov regularization. Some examples of successful image reconstruction are presented.

The three dimensional microwave tomography (3D MT) system of the Electronics and Telecommunications Research Institute (ETRI) comprises an antenna array, transmitting receiving module, switch matrix module and a signal processing component. This system also includes a patient interface bed as well as a 3D reconstruction algorithm. Here, we perform a comparative analysis of image reconstruction results using the assembled system and MRI results, which is used to image the breasts of dogs. Microwave imaging reconstruction results (at 1,500 MHz) obtained using the ETRI 3D MT system are presented. The system provides computationally reliable diagnosis results from the reconstructed MT Image.

Earlier detection of breast cancer is very important. The objective of this study is to develop an inexpensive portable device for simply detecting the existence of breast cancer using microwave. In this paper, we investigated the feasibility of the proposed method for such device by actual measurement, and analyzed the possible detection rate dependent on the tumor size by numerical simulation. Measurement results show that the proposed method is quite feasible, and the simulation results reveal that the detection rate of such device could be more than 60 % for tumor of 5 mm size. The proposed device can be used for self-diagnosis of breast cancer. Next step of our study will be the realization of a proto-type system.

A phase unwrapping method for microwave tomography imaging system was realized and tested. The method uses two adjacent tones. This method can be adapted to a microwave tomography system operating in high frequency band.

A transceiver subsystem for microwave breast imaging system was designed and fabricated. The subsystem consists of a transmitter, a receiver and a 16-channel switch matrix module. The subsystem is operated in the frequency from 500 MHz to 3 GHz and has 130 dB dynamic range and 110 dB channel isolation.

In this paper, we proposed a test-bed system that is constructed to detect the breast cancer. Through arbitrary breast model, we proved the performance of the fabricated test-bed system. Through the application of this microwave tomography technology, we will be able to use as the detector of breast cancers in a human body. By further study, the system will be modified and redesigned to be a clinical test-bed system finally.

A narrow-band preamplifier for fiber-optic millimeter-wave wireless system is presented based on a fully stabilized 0.12 mum pseudomorphic high electron mobility transistor (PHEMT) technology and is realized in a low-temperature co-fired (LTCC) technology. The preamplifier is designed with parallel feedback and T-section matching networks. These networks are used for narrow-band filtering function and for unconditionally stable of circuits. The preamplifier module, in corporation of four amplifying stages, shows measured transimpedance gain of 53 dBOmega, and return loss of less than -10 dB with a 1 dBOmega, ripple around the center frequency. The transimpedance gain difference between bare chip and module is about 3.5 dBOmega