• Journal of Broadcast Engineering
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• v.13 no.4
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• pp.479-487
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• 2008

The method to determine allowable interference criteria is required due to new digital FWSs(Fixed Wireless Systems) adding to allowable frequency bands, besides current FWSs and digital FWSs. In this paper, we suggested a method to define allowable interference between digital FWSs. Types of interference for FWS were defined and channel characteristics were analyzed. Allowable interference criteria were analyzed using the suggested method for M-ary QAM modulations, which is typical modulation technique of digital FWS.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8A
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• pp.829-837
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• 2008

A cellular system with fixed relays is considered to be a technology that can support high data transmission service to wide areas. However, either inter-cell interference or inter-sector interference that can be produced by adding relays to the cellular system with fixed relays does not guarantee high link performance to deteriorate function, so that resource allocation for avoidance of interference is very much important. In the paper, the cellular system performance with repeater relay has been compared with the cellular system performance with relay, and cell coverage expansion at the use of relay repeater has been compared. To compare, this paper has suggested resource allocation method to avoid inter-cell interference and inter-sector interference at installation of fixed relay on the cellular system. The proposed method can allocate different frequency resources on adjacent base stations and relays to reduce interference and to expand high data transmission area, and all of frequency bands are used at each sector to elevate efficiency of the frequency when base stations and relays operate simultaneously.

• Journal of IKEEE
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• v.25 no.4
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• pp.584-590
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• 2021

This paper proposes a removal method of signal interference between ultrasound sensors where ghost signals due to interference are excluded and correct signal is recognized in distance mensurement using ultrasound sensors. The proposed method detects and excludes ghost signals when previous measured distance is compared to current measured distance and the distance difference exceeds a threshold. The threshold is fixed in conventional methods, so ghost signals cannot be correctly excluded when ultrasound sensor or target object move rapidly. On the contrary, to improve accuracy, the threshold is not fixed in the proposed method, and the threshold is adpatively determined based on the relative velocity when ultrasound sensor or target object move. Experiments of distance measurement with ultrasound signal interference are carried out where multiple ultrasound sensors of same type are exploited with maximum interference, and the results show that the proposed method efficiently exclude ghost signals.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.11
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• pp.9-15
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• 2004

We propose optimal interference rejection weight for multistage parallel nulling (MPN) partial parallel interference cancellation (PPIC) receiver previously proposed to enhance the performance of V-BLAST for downlink multiple-input multiple-output (MIMO) multicarrier (MC)-code division multiple access (CDMA) systems. MPN-PPIC method proposed in [1] was based on the parallel interference cancellation (PIC) with fixed interference rejection weight obtained experimentally. However, the fixed weight can not be adapted to various systems efficiently, thus we proposed method for the optimal interference rejection weight based on the received signal to interference and noise ratio (SINR), and the performance of the proposed method was evaluated through computer simulation comparing with the previous method. We obtained performance gains of 2.5 dB ~ 5 dB for BER of 10$^{-3}$ .

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.147-150
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• 1998

To determine the satellite orbital positions under consideration of interference caused by inter-satellite systems is one of the most important issues in terms of optimal usage of satellite network resources. In this paper, we present the orbital positioning method for a new satellite to minimize inter-satellite system interference effect in the fixed satellite communication using a new method. Through the computer simulation, it is clear that the proposed method is suitable to determine the satellite orbital positions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.12
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• pp.2763-2771
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• 1997

To determine the satellite orbital positions considering interference caused by inter-satellite systems is one of the most improtant issues in terms of optimal usage of satellite network resources. In this paper, considering ITU filing situation, we present the satellite orbital positions determination method to minimize iter-satellite system interference effect in the fixed satellite communication using an optimization method. Through the computer simulatio, it was shown that the proposed method is suitable to determine the satellite orbital positions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.156-160
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• 2002

In this paper, we have estimated by means of the theoretical analysis and the simulation of FCA(Fixed Channel Assignment) and CB(Channel Borrowing) in order to consider the CB as a technique to meet ducting interference from adjacent countries. Also, we assumed that the receiving power level of ducting interference with time rate can be characterized by the normal distribution due to the previous measured results, and the ducting interferences which are exceeding the reference power level can be regarded as calls. These calls can be processed by CR assignment and by which sharing channels between cells brings to us the method of meeting the ducting interference to use spectrum resources effectively. However, the spectrum frequency reusing and the interference effects between channels should be considered in CB simulation in the future.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.9
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• pp.39-45
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• 2004

A design method is proposed for the sequence detection with fixed decision delay with less hardware complexity using the concept of the Voronoi diagram and its dual, the Delaunay tessellation. This detector design is based on the Fixed Delay Tree Search (FDTS) detection. The FDTS is a computationally efficient sequence detection algerian and has been shown to achieve near-optimal performance in the severe Intersymbol Interference (ISI) channels when combined with decision feedback equalization and the appropriate channel coding. In this approach, utilizing the information contained in the Voronoi diagram or equivalently the Delaunay tessellation, the relative location of the detector input sequence in the multi-dimensional Euclidean space is found without any computational redundancy, which leads to a reduced complexity implementation of the detector.

• Journal of Advanced Navigation Technology
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• v.21 no.5
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• pp.428-434
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• 2017

In recent years, owing to the growing user demand for the two-way internet service based on the mobile global broadband communications, a new type of satellite terminal has been developed, known as ESIM(Earth Station in Motion). This service was required by Resolution 158(WRC-15) to study on the coexistence with the co-primary FS(Fixed Service) in 27.5-29.5 GHz as a FSS(Fixed Satellite Service) uplink. In this paper, the average received power on ESIM within -10 dB of beam width of FS and its outage probability was analyzed theoretically and also simulated to account for the azimuth angle with uniform distribution. From the results, it can be concluded that this theoretical analysis is very useful to analyze the interference from ESIM into FS based on the statistical and probabilistic method. Therefore, it is necessary to control the azimuth angle due to a moving terminal as well as the inclination angle of moving path, the operation hours, and the speed of ESIM to protect the co-primary FS.

• Journal of Engineering Education Research
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• v.16 no.2
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• pp.24-30
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• 2013

This paper deals with the measurement theory and technique of linear expansion coefficient for solid material using Michelson interferometer. The Michelson interferometer produces interference fringes by splitting a beam of monochromatic light so that one beam strikes a fixed mirror and the other a movable mirror. When the reflected beams are brought back together, an interference pattern results. Precise distance measurements until a quarter of wave length can be made with the Michelson interferometer by moving the mirror and counting the interference fringes which move by a photo diode. This paper represents the application of Michelson interferometer for measuring infinitesimal length system and shows the measurement method of linear expansion coefficients for various materials like copper, aluminum and iron. the results are good agreement with theoretical value within margin of error for each materials.