한가원 교수

A method to detect people in multiple locations using a multiple-input and multiple-output (MIMO) frequency-modulated continuous wave (FMCW) radar system is proposed. A 2-D range-angle map is estimated by digital beamforming with virtual receiver arrays obtained via the operation of time-division multiplexing (TDM) MIMO radar. Phase variations due to human vital signs and movements allow the identification of people from stationary clutter in the range-angle map. To improve the sensitivity of ph

A collocated phased-subarray multiple-input and multiple-output (MIMO) radar system that reduces the number of MIMO channels to implement a large antenna array is proposed. Both the transmitter (TX) and receiver (RX) arrays are divided into phased subarrays, which consist of several RF beamforming antenna elements. Each phased subarray is exploited as an MIMO channel. To estimate the angular information of targets, a hybrid beamforming technique that incorporates RF beamforming of the phased sub

This article proposes a method to detect vocal signals and the corresponding locations of multiple humans using a multiple-input and multiple-output (MIMO) frequency-modulated continuous-wave (FMCW) radar system. The signals of multiple humans are extracted with digital beamforming by the virtual array generated by MIMO radar processing. To remove body motion artifacts that distort the speech information detected by the radar, a body motion effect cancellation method is proposed. The technique a

A phase-extraction technique with multiple frequencies of a frequency-modulated continuous-wave (FMCW) radar is proposed, which allows the detection of target motions exactly. An FMCW chirp signal is decomposed into multiple-frequency continuous-wave (CW) signals to extract modulated phases due to target motions. The demodulated phases at multiple frequencies are summed and averaged. Since the proposed method can extract the phase without performing a fast Fourier transform (FFT), it can overcom

A differential phase Doppler radar sensor with multiple receivers (RXs) to remotely detect human vital signals is proposed, which can reduce common motion artifacts as well as common noises to RXs. This is achieved by differentiating two-phase signals from a pair of collocated RXs. Random motions are decomposed into several kinds of motions with respect to the transmitted beam direction. Six differential phase signals are obtained from the four RX combinations, among which at least one pair can

In this paper, we propose a sub-Nyquist sampling (SNS) orthogonal frequency-division multiplexing (OFDM) radar system capable of reducing the analog-to-digital converter (ADC) sampling rate in OFDM radar without any additional manipulations of its hardware and waveform. To this end, the proposed system utilizes the ADC sampling rate of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B/L</i> to sample the received baseband signal with a bandwidth

A body motion artifact cancellation (BMAC) technique is proposed to detect human cough signals using a frequency-modulated continuous-wave (FMCW) radar. Human coughs are spontaneously accompanied by large-scale body motions, which overwhelm small-scale vibration signals induced by coughing. To mitigate these effects, motion-induced phase variations are estimated and compensated at respective frequencies of an FMCW signal. The cough signals are extracted from range profiles of the phase-compensat

This article proposes a range-angle decoupling technique for use in a high-resolution multiple-input multiple-output (MIMO) radar system. A high-resolution radar system exploiting both a wide modulation bandwidth and a large array aperture is detrimentally affected by what is known as the range-angle coupling (RAC) effect. This effect severely degrades the angular resolution at off-boresight angles in conventional digital beamforming radar. To obviate this effect, a wavelength-dependent beamform

A multiple-input and multiple-output (MIMO) differential radar using null point beams is proposed to detect vital signs of multiple people in the presence of random body movements. Multiple beams are employed by digital beamforming of virtual receiver arrays obtained through a MIMO operation. A differential method using null points of array beam patterns is proposed to reduce motion artifacts. It effectively magnifies magnitude differences of received signals from adjacent two beams which have s

A differential-phase radar with amplitude-compensated complex signal demodulation (ACCSD) is presented., which can detect vital-signals from one-side of the human body even during back-and-forth random movements. Differential signal demodulation is achieved using the proposed ACCSD method. Compared with the conventional complex signal demodulation (CSD) method, the proposed method can avoid a distortion due to amplitude variations of baseband signal. Experiments also show that the proposed ACCSD

This letter proposes a method to detect the angular locations of human targets using a multiple-input–multiple-output (MIMO) monopulse radar system. Sum and difference beams used for monopulse processing are simply implemented by digital beamforming of a virtual array generated by collocated MIMO radar. Human targets are readily distinguished from stationary clutter based on the phase variations in their signals, which are detected by estimating the curve lengths (CLs) of the I/Q trajectories. A

The ultimate goal of integrated sensing and communication (ISAC) deployment is to provide coordinated sensing and communication services at an unprecedented scale. This paper presents a comprehensive overview of network-level ISAC systems, an emerging paradigm that significantly extends the capabilities of link-level ISAC through distributed cooperation. We first examine recent advancements in network-level ISAC architectures, emphasizing various cooperation schemes and distributed system design

This paper presents a high-resolution automotive multi-input multi-output (MIMO) radar with sparse arrays using beamspace matrix completion. Sparse arrays, while offering a larger aperture than uniform arrays with an equivalent number of antenna elements, suffer from higher sidelobe levels due to missing elements (holes). To address this issue, an array interpolation technique employing low-rank matrix completion through a Hankel matrix formation has been proposed. However, the computational dem

The deployment of integrated sensing and communication (ISAC) in wireless networks brings along unprecedented vulnerabilities to authorized passive sensing, necessitating the development of secure sensing solutions. Unlike traditional wireless communication, where data security can be enhanced through data encryption, sensing security is more challenging to achieve. This is because sensing parameters are embedded within the target-reflected signal leaked to unauthorized passive radar sensing eav

This paper presents a signal processing method to detect human cough signals with a millimeter-wave frequency-modulated continuous-wave (FMCW) radar. Tiny vibrations induced by coughing can be extracted by using the phase demodulation technique of the FMCW radar. A body motion artifact cancellation (BMAC) technique is exploited to suppress motion artifacts, which can easily overwhelm and distort the small vibrations. This allows measuring the vibration frequency of the cough signal even when lar