• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.11
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• pp.17-23
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• 2012

Products of Wi-Fi devices in recent years offer higher throughput and have longer signal coverage which also bring unnecessary signal interference to neighboring wireless networks, and result in decrease of network throughput. Signal interference is an inevitable problem because of the broadcast nature of wireless transmissions. However it could be optimized by reducing signal coverage of wireless devices. On the other hand, smaller signal coverage also means lower transmission power and lower data throughput. Therefore, in this paper, we analyze the relationship among signal strength, coverage, interference and network throughput by simulation on various network topology.

• 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.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.10 s.352
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• pp.55-59
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• 2006

In cellular OFDMA(Orthogonal Frequency Division Multiple Access) systems, each subcarrier may suffer from different amount of interferences from neighbor cells. Suppose that it is possible to accurately estimate inter-cell interferences for each subcarrier, the performance can be considerably improved by applying SINR(Signal to Interference and Noise Ratio) weighting. This paper proposes an inter-cell interference estimation method for cellular OFDMA systems. The proposed method extracts amounts of noise and interferencesby eliminating the channel variation effects of pilot symbols caused by frequency offset, timing offset mobile velocity, and delay spread.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.1
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• pp.40-47
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• 2013

By virtue of Rec. ITU-R P.1546 and geography information system, interference analysis for the fixed wireless system and radar has been presented based upon the frequency-distance rules with minimum coupling loss, and a comprehensive methodology for assessing interoperability between systems was examined in terms of received signal, protection ratio, frequency dependent rejection. Also to find the antenna gain from a discrimination angle, a useful S-I plane was introduced based on signal and interference vectors derived from the real map with geographic information. To show some computational results, geography information on the map was taken for the given area, and field strength and path profile were illustrated for the radar and fixed wireless system operating at 2.7 GHz, for convenience. In addition the interference effect of receiver was also checked as a function of radar beam direction including protection ratio and frequency dependent rejection. The developed interference analysis can be actually applied to evaluate interoperability for wireless systems in the VHF and UHF bands.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.1
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• pp.64-72
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• 1986

The error rate equation fo DS-BPSK(Direct Sequence Binary Phase Shift Keying) signal transmitted through the nonlinear satellite transponder has been derived in the cochannel interference and downlink Gaussian noise environment. The input to the satellite transponder is the superposition of DS-BPSK signal with one interfere which is a cochannel wide-band PN signal. The error rate performance of DS-BPSK system has been evaluated and shown in figures in terms of carrier to interference power ratio(CIR), downlink signal to noise power ratio(downlink SNR) and process gain. In the analysis, it has been shown that the use of a hard limiter in DS-BPSK satellite system leads to the generation of narrow-band intermodulation products which is independent of the process gain. Also it is known that the error rate performance can be improved in the low levels (below 10dB) of CIR as the CIR increase. As the process gain varies from 10 to 100 the curve gives the about 10 dB gain in downlink SNR to maintain a fixed error rate.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.3
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• pp.945-964
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• 2014

In this paper, we investigate the performance of Signal to Leakage and Noise Radio (SLNR) based user scheduling in uplink of multi-cell with large-scale antenna system. Large antenna array is desired to improve the performance in future system by providing better beamforming capability. However, some studies have found that the signal channel is 'hardened' (becomes invariant) when the antenna number goes extremely large, which implies that the signal channel aware user scheduling may have no gain at all. With the mathematic tool of order statistics, we analyzed the signal and interference terms of SLNR in a homogeneous multicell network. The derived distribution function of signal and interference shows that the leakage channel's variance is much more influential than the signal channel's variance in large-scale antenna regime. So even though the signal channel is hardened, the SLNR-based scheduling can achieve remarkable multiuser diversity (MUD) gain due to the fluctuation of the uplink leakage channel. By providing the final SINR distribution, we verify that the SLNR-based scheduling can leverage MUD in a better way than the signal channel based scheduling. The Monte Carlo simulations show that the throughput gain of SLNR-based scheduling over signal channel based scheduling is significant.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11A
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• pp.1038-1044
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• 2010

Interference may severely deteriorate performance in wireless communication. Han-Kobayashi scheme splits each user's signal into private and common information so that the receiver removes the other's common signal for partial interference cancellation. This paper proposes an optimal power allocation to private and common signals for Han-Kobayashi scheme by using required SNR in a private information only system. Numerical results show that the proposed power allocation is quite close to the optimal power allocation based on exhaustive searches.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3A
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• pp.119-128
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• 2003

A space diversity technique was applied to the conventional optimal beamforming structure using antenna arrays at the base station receiver in the wireless mobile communication system to get performance enhancement due to interference rejection and fading resistance ability of it. To demonstrate the benefit of proposed system, we derived output signal to interference plus noise ratio (SINR) of combined signal from all sub-array groups considering the fading effects and compared with the beamforming-only system. From the analysis and simulation results, we showed that the proposed system can provide high performance gain under Rayleigh fading channel.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.2
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• pp.153-158
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• 2020

In this paper, we studied an algorithm for estimating a desired target by removing noise and interference in a wireless communication environment. When an information signal with a mixture noise and interference receive a receiver, noise and interference signals must be removed to accurately estimate a desired target. In order to divide the received signal region into two spatial, a power spectrum is obtained by analyzing a correlation matrix, covariance, eigen vector, and eigen value. The proposed spectrum is an algorithm that can remove noise and interference, and analyzes the existing algorithm and target estimation performance through simulation. As a result of simulation, the target estimation resolution of existing algorithm is more than 10°, but the resolution of the proposed algorithm is less than 10°. The proposed algorithm has improved the resolution of about 5° than the exiting algorithm. The proposed algorithm proved that the target estimation accuracy and resolution are superior to the existing algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12A
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• pp.1097-1104
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• 2010

This paper presents the signal-to-noise ratio (SNR) and signal-to-interference plus noise ratio (SINR) estimation based on A-Preamble of IEEE 802.16m IMT-Advanced WiMax system with simulation results. The downlink signal of IEEE 802.16m has two kinds of A-Preambles: the PA-Preamble and the SA-Preamble. This paper proposes the effective method of estimating SNR and SINR with A-Preambles, and also shows that this method can recognize the ICI(Inter-Carrier-Interference) occurrence due to doppler frequency. With the recognition of ICI, the mobile station can save the power by operating 1-tap equalizer in usual cases, and activating ICI mitigation module only when it perceives the ICI occurrence.