Search results for: Myung-Don Kim
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A compact UHF cross dipole antenna with reconfigurable radiation pattern is presented. The proposed antenna achieves beam-forming using a modified Yagi antenna concept and the passive parasitic elements. The measured impedance bandwidth of the cross dipole antenna is 884–915 MHz. It is possible to use reflector and director depending on the ON, OFF state of the pin diode. The measured antenna peak...
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IEEE Communications Letters > 2017 > 21 > 2 > 246 - 249
In this letter, a unified propagation graph modeling approach is proposed, which is applicable to predicting multipath radio propagation by considering both specular components (SCs) and diffuse components (DCs). In this approach, the semi-deterministic graph modeling is used to generate multi-bounce DCs, and a single-lobe directive model is applied to reproducing individual single-bounce SCs together...
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In this paper, we present the experimental path loss models for a typical indoor office propagation scenario. Channel measurements have been performed using a wideband channel sounder in the 28 and 38 GHz frequency bands. We derive path loss exponents and shadow fading factors based on the two popular path loss models, i.e., Close-in (CI) free space reference distance model and Floating-intercept...
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To meet the increasing demand for 5G high datarate communications, millimeter-wave frequency bands are expected to be utilized. However, the existing channel models are not applicable to predict channel behaviors in these frequency bands. In this paper we investigate millimeter-wave channel model parameters including path loss exponents, delay and angular spread, and clustering parameters based on...
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Millimeter-wave has come into the spot-light as the frequency band of the next generation communication systems. Prior to millimeter-wave communication system designs, the study of propagation characteristics is necessary. Especially, the power delay profile is one of the most important characteristics of channel fading that can be utilized for determining symbol duration. For the reason, we analyzed...
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In this paper, we compared the performance of the Space-Alternating Generalized Expectation-maximization (SAGE) algorithm and Bartlett Beamformer (BBF) based on 28 GHz field measurement data. The performance was evaluated by: (1) the similarity of dispersion characteristics such as delay spread (DS) and angular spread (AS), (2) computational complexity by comparing computation time. Our results showed...
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Path loss characteristics are usually studied in terms of distance and/or frequency under omni-directional antenna assumptions. When directional antennas are employed, an additional power loss may arise due to the beam mis-alignment between TX and RX beam axes. This paper investigates this additional power loss behavior based on field measurement data. The measurements were conducted in downtown Seoul...
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Highly directive antennas or various beamforming techniques using large antenna arrays are expected to be adopted for overcoming the severe path loss on millimeter-wave bands. This paper investigates the effect of antenna beamwidth on millimeter-wave channel characterization and modeling. The indoor channel measurement campaigns were performed using a wideband channel sounder in the frequency band...
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Since millimeter-wave (mmWave) frequency bands are strong candidates in new spectra for 5G mobiles, standardized propagation channel models are anticipated to be developed for 5G system evaluation and interference analysis. Instead of developing a new model, this paper takes the tact of examining the practicality of applying already existing, and commonly-used, ITU-R path loss models to the mmWave...
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Propagation characteristics of millimeter-wave are being widely studied for utilization of the fifth generation (5G) mobile communication systems. To overcome the severe path loss on the high frequency band, highly directive antennas or beamforming techniques using large array antennas can be used to establish a reliable communication link between a transmitter and a receiver. In this paper, a recently...
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To analyze multipath propagation channels from field measurement data, multipath parameter extraction algorithms are utilized. Among them, the Space-Alternating Generalized Expectation-maximization (SAGE) provides high-resolution performance on parameter estimations although it requires high computational complexity. On the other hand, Bartlett Beamformer (BBF) with low complexity is known to provide...
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To analyze multipath propagation channels from field measurement data, multipath parameter extraction algorithms are utilized. Among them, the Space-Alternating Generalized Expectation-maximization (SAGE) provides high-resolution performance on parameter estimations although it requires high computational complexity. On the other hand, Bartlett Beamformer (BBF) with low complexity is known to provide...
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This paper introduces a channel sounder to measure the millimeter wave channel characteristic by using a swept time delayed cross-correlation. The channel sounder is implemented to measure the multipath channel characteristics and a variety of wireless space channel parameters generated at 28 GHz. we present a system parameter of the implemented channel sounder, and show a performance for multi-path...
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In this paper, we analyze temporal and spatial distribution characteristics of multipath components considering for device-to-device (D2D) communications scenarios in urban very high-rise environments. Using the 3.7GHz wideband channel sounder and uniform circular array antennas, a channel measurement campaign has been performed at Gangnam of Seoul in Korea which the place very high-rise buildings...
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Due to the limitation of power budget in millimeter-wave communication links, high-gain horn antennas are typically exploited instead of low-gain omni-directional antennas, especially for measurement campaign. To study millimeter-wave propagation characteristics, measured channels with a single set of narrow beamwidth antenna are required to synthesize wider beam width properties including omni-directional...
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Wideband characteristics in the 28GHz band were measured at various environments using narrow beamwidth antennas. In this paper, we present delay spreads of urban low-rise area with two line of sight cases, one is a face-to-face and the other is non-face-to-face between antennas. Also, we present a distance characteristic of delay spread based on measured data.
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For 5G communications, millimeter-wave frequency bands are considered strong candidates for new spectra. However, propagation studies in these bands are still in their initial stages. Using 28 GHz measurements collected in railway and airport passenger terminals, this paper investigates path loss characteristics of large indoor environments. In particular, we conducted measurement campaigns in passenger...
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Millimeter-wave propagation characteristics and channel models are being recently studied for applicability of the fifth generation (5G) mobile communication systems. To overcome the larger path loss on the higher frequency band above 6 GHz, highly directive antennas or beamforming techniques using large array antennas can be used to establish a reliable communication link between a transmitter and...
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The deployment of 5G mobile communications at millimeter-wave frequency bands is currently the subject of intense debate. To help in conducting feasibility, planning and interference analysis studies for the introduction of millimeter-wave frequencies, this paper investigates path loss characteristics with steerable directional antenna measurements at 28 GHz. In particular, we focus on propagation...
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In this paper, we investigate the 28 GHz path loss characteristics in urban environments. We present a wideband channel sounder used to measure spatial and temporal channel characteristics in the 28 GHz frequency band. Channel measurement campaigns are carried out in typical urban low-rise and very high-rise environments in Korea. Based on measured data, we present results of path loss exponents and...
