• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1194-1199
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• 2010

In this paper, for a relay-based cellular network, a interference avoidance beamforming technique is proposed to enhance direct link capacity while minimizing loss in the capacity of concurrent relaying link. A direct link is transmitted by beamforming at the transmitter, and the relaying link with the least interference to the direct link is scheduled to transmit data by a collision avoidance scheduling algorithm. Simulation results show that the proposed IA beamforming provides a considerable direct link capacity enhancement while minimizing relaying link capacity loss by effectively mitigating inference between concurrent direct and relaying links only with limited feedback.

• Journal of Advanced Navigation Technology
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• v.13 no.3
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• pp.344-350
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• 2009

In this paper, interference effect given from non-geostationary orbit link into geostationary orbit link is analyzed by BER performance. To analyze the interference effect with the angle between satellites, the angular separation is changed from $1^{\circ}$ to $8^{\circ}$, and the number of the satellite is also changed from 1 to 4 for analyzing it. From the results, the interference effect into the geostationary orbit service from non-geostationary orbit link is more increased according to the angular separation that is decreased. Especially, the small angle gives more interference effects to the geostationary orbit link. Furthermore, more number of interfering satellites gives more interference effect to the geostationary orbit link. However, the angle between the interference orbit and geostationary orbit gives more effect to the system performance then the number of the interference orbit.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.4
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• pp.651-669
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• 2013

In this paper, we study a novel routing algorithm based on load balancing for multi-channel wireless mesh networks. In order to increase the network capacity and reduce the interference of transmission streams and the communication delay, on the basis of weighted cumulative expected transmission time (WCETT) routing metric this paper proposes an improved routing metric based on load balancing and channel interference (LBI_WCETT), which considers the channel interference, channel diversity, link load and the latency brought by channel switching. Meanwhile, in order to utilize the multi-channel strategy efficiently in wireless mesh networks, a new channel allocation algorithm is proposed. This channel allocation algorithm utilizes the conflict graph model and considers the initial link load estimation and the potential interference of the link to assign a channel for each link in the wireless mesh network. It also utilizes the channel utilization percentage of the virtual link in its interference range as the channel selection standard. Simulation results show that the LBI_WCETT routing metric can help increase the network capacity effectively, reduce the average end to end delay, and improve the network performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.919-923
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• 2009

In this paper, interference effect given from non-geostationary orbit link into geostationary orbit link is analyzed by BER performance curve. To analyse the interference effect with the angle between satellites, the angular separation is changed from $1^{\circ}$ to $8^{\circ}$, and the number of the satellite is also changed from 1 to 4 for analyzing it. From the result under those research environments, the interference effect into the geostationary orbit service is more increased according to the angular separation that is decreased. Especially, the small angle gives more interference effects to the geostationary orbit link. Furthermore, more number of interfering satellites gives more interference effect to the geostationary orbit link.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.795-800
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• 2000

In a parallel manipulator, there are three constraints that determine workspace: link length constraint, passive joint angle constraint, and interference among links. Generally, the link length constraint is the most dominant. The interference among links is, however, also an important parameter in designing a desired parallel manipulator. In this study, the interference among links is mathematically modeled by considering the links as a line and a cylinder of radius of twice the link radius, and a new algorithm is suggested to check if arbitrary two links interfere each other or not. The workspace of a cubic parallel manipulator is illustrated in a 2D space satisfying the three constraints.

• Journal of Advanced Navigation Technology
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• v.20 no.1
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• pp.45-52
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• 2016

In this paper, the method of interference analysis and its simulation have been suggested for the frequency sharing between aeronautical radio navigation systems and Link-16 platforms. In order to get the criteria for interoperability, the algorithm of interference analysis and protection ratio are derived to assure frequency sharing. Also the receiving power of wireless system has been illustrated with the help of radio propagation model of ITU-R Rec. P.1546 in VHF-UHF band. Finally the required receiving power or separation distance between DME/TACAN beacons and Link-16 ground station terminals has been considered based on system link budget in terms of evaluating interoperability as well as actual applications. As a result, if the suggested interference analysis and test set-up are applied to the field trial, it will lead to easy means to make a decision on interoperability over the existing incumbent systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7A
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• pp.440-450
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• 2003

The reverse link of a spectrally overlaid macrocell/microcell cellular CDMA system supporting multimedia traffic is characterized in terms of the required signal power, interference, and capacity. Several narrowband subsystems are overlaid with a wideband subsystem in macrocells, while a single wideband subsystem is operated in a microcell with the same spectrum as the macrocell wideband subsystem. Using a typical propagation model the reverse link signal power and interference are characterized as the relative user signal power and the cross-tier interference factors between the macrocell and the microcell. The reverse link capacity of the overlay system is then analyzed. Analytical results show that the dominant parameters affecting the system performance are the spectral overlay ratio and the distance between the microcell and macrocell base stations. In particular, when the distance equals a half of macrocell radius, optimum performance can be achieved by minimizing the cross-tier interference factors. These results can be applied to CDMA multimedia network planning in heavily populated traffic areas.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.6
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• pp.119-125
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• 2008

In this paper, we proposed the modeling of UHF frequency environment in a random mountainous area with line of sight. A transmitting station is defined as wanted transmitter(Wr) and a receiving station is defined as victim receiver(Vr). These set up victim link. A interference transmitter(It) and wanted receiver(Wr) set up interference link. We compared measured data at random mountainous area with data of the result using spectrum engineering advanced monte calo analysis tool(SEAMCAT), interference simulation based on the monte-carlo method. The desired received signal strength(dRSS) of SEAMCAT had the calculated error of 70% from the measured received signal strength because there was a topographical effect. Therefore, the effect of diffraction interference was included to lessen the power of transmitter in the proposed simulation. The cause of received power error are cable loss and errors of a measuring instrument. The proposed simulation modeling in UHF frequency environment expect that is the useful study on interference analysis and reassignment of broadcasting frequency.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.1
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• pp.26-51
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• 2009

In this paper, we propose an empirical framework for modeling and emulating interference in multi-hop wireless ad-hoc networks. Wireless interference causes wide variation in the frame delivery rate at a link, and thus we cannot represent the state of the link with only two states, connected state and disconnected state, as in wired networks. We first investigate wireless interference in detail, in order to accurately calibrate the interference and identify its underlying attributes, and then we simulate the diverse occurrences and effects of interference, after incorporating the scheme into a simulation tool. Based on these observations, we devise a modeling and simulation framework with several control parameters, and perform an extensive set of simulation studies. The simulation results indicate that the proposed framework enables us to examine various attributes of wireless interferences and their effects on wireless network protocols and systems.

• Journal of Advanced Navigation Technology
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• v.4 no.2
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• pp.182-190
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• 2000

In this paper, interference effects between NGSO and HAPS in the feeder link have been simulated and analyzed by means of calculating excess time percent and duration below the ell protection ratio. As the results, in the case of HAPS interference into NGSO, it can be obtained that the lowest C/I values are 20.42dB in 50km and 12.73dB in 20km of HAPS altitudes, respectively. And in the case of NGSO interference into HAPS, it can be obtained that the lowest ell values are 13.94dB and 10.42dB respectively. HAPS system has more interference reception from other systems or effects more interference into other systems as its altitude is lower. Also, the lowest ell values are appeared at difference time with its altitude.