• Journal of electromagnetic engineering and science
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• v.18 no.4
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• pp.254-260
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• 2018

In this study, we suggest an emulator for generating multiple heterogeneous interference signals in the Korean radio frequency identification/ubiquitous sensor network (RFID/USN) frequency band. The proposed emulator uses only one universal software radio peripheral to generate multiple heterogeneous interference signals more economically. Moreover, the physical and media access control parameters can be adjusted in real time using the LabVIEW program, thereby making it possible to create various time-varying interference environments easily. As an example showing the capability of the proposed emulator, multiple interference signals consisting of a frequency-hopping RFID signal and two LoRa signals with different spreading factors were generated. The generated signals were confirmed in both frequency and time domains. From the experimental results, we verified that our emulator could successfully generate multiple heterogeneous interference signals with different frequency and time domain characteristics.

• Journal of electromagnetic engineering and science
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• v.12 no.1
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• pp.94-100
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• 2012

Radio interference has been occurring in mobile communication services on the southern seashore in Korea. Monitoring the radio interference signal revealed that the main reason for the radio interference was a radio ducting signal coming from the seaside of Japan. In this paper, we have analyzed the effect of interference on WiMAX service using a 2.5 GHz frequency band between Korea and Japan. We focus on the interference scenario from base station to base station and we use the Minimum Coupling Loss (MCL) method for interference analysis and the Advanced Propagation Model (APM) for calculating the propagation loss in ducts. The propagation model is also compared with experimental measurement data. We confirm that the interfering signal strength depends on the antenna height and this result can be applied to deployment planning for each system with an interference impact acceptable to both parties.

• Journal of electromagnetic engineering and science
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• v.9 no.4
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• pp.182-187
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• 2009

When we assign frequency resources to a new radio service, the existing services need not to be interfered with by the new service. Therefore, when we make a frequency assignment, a guard band is necessary to separate adjacent frequency bands so that both can transmit simultaneously without interfering with each other. In this paper, we propose an efficient frequency guard band decision rule for avoiding interference between radio services. The guard band is established based on the probability of interference in the previously arranged scenario. The interference probability is calculated using the spectrum engineering advanced Monte Carlo(MC) analysis tool(SEAMCAT). After applying the proposed algorithm to set up the frequency guard band, we can decide on the guard band appropriately because the result satisfies the predefined criterion.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.691-693
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• 2015

Radio sources are very weak, as they can travel through large distances. Radio sources also have photons with low energies compared to others electromagnetic waves (EM). Microwave photons have a little more energy than radio waves, infrared photons have still more, then visible, ultraviolet, X-rays, and the most energetic electromagnetic wave is gamma-rays. Radio astronomy studies are restricted due to radio frequency interference (RFI) produced by people. If this disturbance is not minimized, it poses critical problems for astrophysical studies. The purpose of this paper is to profile RFI maps in Peninsular Malaysia with a minimum mapping technique for RFI interference. Decision-making processes using GIS (Geographical Information System) for the selection requires gathering information for a variety of parameters. These factors affecting the selection process are also taken into account. In this study, various factors or parameters are involved, such as the availability of telecommunications transmission (including radio and television), rainfall, water lines and human activity. This mapping step must be followed by RFI site testing in order to identify areas of low RFI. This study will benefit radio astronomy research, especially regarding the RFI profile.

• Journal of electromagnetic engineering and science
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• v.18 no.1
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• pp.58-62
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• 2018

In this study, we propose a software-defined radio-based frequency interference emulator in the space-time domain. This emulator can easily model actual interference environments because of the versatile programming capability of the universal software radio peripheral and LabVIEW. As an example of an interfering network using the contention-based multiple access scheme in the time domain, we emulate a coordinated Wi-Fi network that consists of one access point and two Wi-Fi nodes. Results show that our emulator can successfully model multiple interfering signals in the Wi-Fi network and easily adjust various space-time domain parameters.

• Journal of electromagnetic engineering and science
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• v.6 no.1
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• pp.76-81
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• 2006

Ultra wideband(UWB) technologies have been developed to exploit a new spectrum resource in substances and to realize ultra-high-speed communication, high precision geo-location, and other applications. The energy of UWB signal is extremely spread from near DC to a few GHz. This means that the interference between conventional narrowband systems and UWB systems is inevitable. However, the interference effects had not previously been studied from UWB wireless systems to conventional wireless systems sharing the frequency bands such as Broadcasting system. This paper experimentally evaluates the interference from two kinds of UWB sources, namely a orthogonal frequency division Multiplex UWB source and an impulse radio UWB source, to a Broadcasting transmission system. The receive power degradations of broadcasting system are presented. From these experimental results, we show that in all practical cases UWB system can coexist 35 m distance in-band broadcasting network.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.2
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• pp.196-208
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• 2002

Since radio interference has occurred in the TRS frequency band in the south coastal area, Korea from 1994, similar interference has been observed in the mobile-cellular frequency band. Measurement showed that the sources of the radio interference are those from the base stations for digital cellular systems in Japan. This because the receiving frequency of the base stations in Korea is same as the transmitting frequency of the base stations in Japan. Since the distance between Korea and Japan is 240 ~ 300 km, we can conclude that the main reason of the interference is ducting. In this paper a ducting channel is modeled by split-step DMFT algorithm, and simulation results for measured index profile far east coast and west sea area are analyzed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.10
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• pp.945-948
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• 2016

Recent premium smartphones commonly employ a metal frame and this trend is currently spreading over mid-range smartphones. However, the metal frame becomes a good coupling path of electromagnetic noises emitted from digital components in smartphones and then increases radio-frequency interference(RFI) to RF antennas located at top and bottom sides of smartphones. This paper proposed a metal frame with EBG(Electromagnetic Band Gap) structure to reduce the noise coupling to antenna by suppressing surface wave on the metal frame. By simulation, it is confirmed that the proposed metal frame with $7{\times}6$ mushroom-type EBG array pattern with multi-via can reduce the noise coupling to RF antenna by about 20 dB.

• Journal of electromagnetic engineering and science
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• v.9 no.3
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• pp.141-145
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• 2009

Interference scenarios involving and a methodology for a terrestrial international mobile telecommunication(IMT) system and mobile-satellite service(MSS) system in a co-channel environment are established. Taking into account a practical deployment situation for both systems, a computational simulation of interference in terms of the ratio of interference power to thermal noise(I/N) is performed in order to evaluate the co-frequency interference with the IMT system caused by the MSS system. The methodology and results could be used for planning an IMT deployment without an unacceptable interference impact caused by the MSS system.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.567-571
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• 2003

Owing to the insufficient satellite resources such as frequency and orbit, the interest in the sharing of these resources has been increasing. ITU-R has been studying on the power limitation, the interference mitigation techniques etc. in order to facilitate the frequency sharing between different systems. Therefore, we studied on the interference mitigation techniques between HEO FSS system and GSO FSS network. We performed the simulation using four mitigation techniques and, based on the results of simulation, evaluated these techniques.