• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.8
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• pp.1587-1592
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• 2012

Analysis on co-use parameters in TV frequency channels is essential to utilize a TV White Space(TVWS) efficiently. A transmission probability of interfering transmitter can be used as some criteria for performance evaluation of the systems that co-use the cochannels. We considered a duty cycle as a parameter for getting the method how heterogeneous systems can use simultaneously a co-channel in TVWS. We analyze the transmission probability of interfering transmitter with an assumption that the probability is the same as the duty cycle, a time that it spends in an active state as a fraction of the total under consideration. In order to make an analysis of relationship between duty cycle and performances of two systems. We take into consideration on the case that WLAN is an victim receiver and WiBro is a interfering transmitter. Analyzed coexistence results may be widely applied into the technique developed to get the coexisting condition for wireless devices using many communication protocols in same frequency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.2A
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• pp.83-94
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• 2012

Various wireless communication devices or network such as WRAN and WLAN will coexist in the TVWS(TV White Space). Because of this coexistence, the wireless devices which use the TVWS have to avoid interfering to not only licensed TV receiver and wireless microphone but also homogeneous or heterogeneous TVBD(TV Band Device)s. In this paper, we propose two frequency sharing methods for the coexistence of WLAN and WRAN in terms of interference reduction and throughput enhancement in both homogeneous and heterogeneous networks. One is the WRAN spectrum etiquette to provide more wide bandwidth for WLAN users and the other is the WLAN frequency selection methods to improve the throughput performance. The simulation results have confirmed the throughput improvement of the proposed methods. Moreover, the proposed methods is also applicable to improve the throughput performance and reduce interference of similar systems working in a cognitive manner.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.63-72
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• 2018

Theoretical modelling and computational results for frequency coordination are presented based upon minimum coupling loss regarding the same or different wireless systems. Essential parameters involved in frequency coordination are discussed in view of system characteristics, propagation model, availability and protection ratio, frequency dependent rejection or adjacent channel interference ratio, discrimination angle, and its computational results are also evaluated. To illustrate frequency coordination procedure, received interference power between fixed wireless system of victim and mobile base station of interferer are analyzed in urban or sub-urban area and also compared with maximum allowable interference power as functions of discrimination angle and distance for assumed system parameters. The proposed method will play a practical role in technical analysis on co-existence or interoperability for the various wireless systems needed for frequency coordination.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.1
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• pp.11-17
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• 2001

This paper introduces an interference analyzer based on the statistical approach called the Monte Carlo methodology, which has been chosen as one of the interference analyzing techniques in ITU-R. Furthermore, using the interference analyzer developed in this paper with modified Hata model, computer simulation is performed to examine probability of interference affecting between the base stations with FDD and TDD modes for IMT-2000. Through the simulation results, it is confirmed that two different systems with FDD/TDD modes of same frequency bands can be simultaneously used in a cell without significant interference, under the parameter conditions specified in this paper.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.7
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• pp.1364-1369
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• 2012

We make an analysis of maximum allowable transmission output level to get the solution how heterogeneous systems between adjacent channels can be used in TVWS(TV White Space). The two applied systems are WLAN and WiBro and the overall performances are analyzed based on simulation results according to various density and transmission output of interfering transmitter. In order to get the relationship between interfering density of two systems and allowable maximum transmitter output, we consider the case that a WLAN is an interfering transmitter and a WiBro is a victim receiver. Each simulation results, obtained by free space channel model, are analyzed by SEAMCAT. Coexistence results may be widely applied into the technique development to get the coexisting condition for wireless devices using many communication protocols in an adjacent frequency and a same frequency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.2
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• pp.254-262
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• 2016

With the increased demand for automotive radar systems, mutual interference between vehicles has become a crucial issue that must be resolved to ensure better automotive safety. Mutual interference between frequency modulated continuous waveform (FMCW) radar system appears in the form of increased noise levels in the frequency domain and results in a failure to separate the target object from interferers. The traditional fast fourier transform (FFT) algorithm, which is used to estimate the beat frequency, is vulnerable in interference-limited automotive radar environments. In order to overcome this drawback, we propose a high-resolution frequency estimation technique for use in interference environments. To verify the performance of the proposed algorithms, a 77GHz FMCW radar system is considered. The proposed method employs a high-resolution algorithm, specially the multiple signal classification and estimation of signal parameters via rotational invariance techniques, which are able to estimate beat frequency accurately.

• Journal of Satellite, Information and Communications
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• v.9 no.1
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• pp.107-114
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• 2014

The satellite 2.1 GHz frequency bands, 1980-2010 MHz and 2170-2200MHz are allocated for mobile satellite service including satellite IMT, while it does not preclude the use of these bands for mobile services. The concept of an integrated satellite/terrestrial network has been introduced in worldwide because the terrestrial use in these bands adjacent to existing terrestrial IMT bands is attractive to provide mobile broadband services. The integrated satellite/terrestrial infrastructure with a high degree of spectrum utilization efficiency has the ability to provide both multimedia broadband services and public protection and disaster relief solutions. In addition, it is required to consider interference issues between the terrestrial and satellite components in order to reuse the same frequency band to both satellite and terrestrial component. This paper analyzes the interference for satellite uplink in the satellite/terrestrial integrated system and the interference reduction scheme for satellite uplink interfered by terrestrial user equipment.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.81-88
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• 2013

The satellite 2.1 GHz frequency bands, 1980-2010 MHz and 2170-2200MHz are allocated for mobile satellite service including satellite IMT, while it does not preclude the use of these bands for mobile services. The concept of an integrated satellite/terrestrial network has been introduced in worldwide because the terrestrial use in these bands adjacent to existing terrestrial IMT bands is attractive to provide mobile broadband services. The integrated satellite/terrestrial infrastructure with a high degree of spectrum utilization efficiency has the ability to provide both multimedia broadband services and public protection and disaster relief solutions. In addition, it is required to consider interference issues between the terrestrial and satellite components in order to reuse the same frequency band to both satellite and terrestrial component. This paper analyzes the interference for satellite downlink in the satellite/terrestrial integrated system and presents the interference mitigation techniques for satellite mobile earth station interfered by terrestrial base stations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.11
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• pp.1323-1326
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• 2012

In military applications, many radar systems are simultaneously operated at a close range. In particular, the frequency allocation must be executed for operating the homogeneous radar systems at the same time. As many radar systems are simultaneously operated with overlapping frequency bands, interference between systems inevitably occurs. Because interference can degrade radar performance, suppression of interference is a critical issue in radar systems. In this letter, we analyze the interference between two FMCW radars. In addition, time synchronization method between radars using mutual interference is proposed. Experiments are carried out to validate the proposed method. The results demonstrate that the proposed method is suitable for real radar systems.

• The Journal of the Acoustical Society of Korea
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• v.41 no.1
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• pp.70-75
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• 2022

The critical bandwidth represents response interactions with respect to a signal tone and their neighboring bands. This study was to analyze the critical bandwidths of a clinically important 500 Hz tone in Korean young male and female subjects (male = 10, female = 10) at a conversational level (60 dB HL). Data were measured with notched band noise and two alternative forced choice methods. Results showed that the critical bandwidth was slightly greater (95 Hz) than the previous Western measures. There were no statistically significant differences in gender, nor were there any significant differences in lateralization of the ear (p > 0.05). These results may have implications in optimizing effective tinnitus masking or the related clinical applications.