• The Journal of the Acoustical Society of Korea
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• v.17 no.3E
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• pp.58-66
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• 1998

In this paper, we analyze the effects of interference canceller on the performance of multitone DS/CDMA system proposed by Vandendorpe[5]. There are various kinds of interference canceller suggested by different researchers including parallel and successive cancellers and we adopt a canceller used by Yoon et al.[9] which is a kind of parallel canceller. We consider three kinds of interferences, that is, multipath interference(MPI), interchannel interference(ICI) and multiple access interference(MAI). The ICI is the interference between multitones. The equations for variances. are derived for the inteferences and thermal noise used for signal to noise ratio calculation. We also consider RAKE reception over multipath channel which is modeled as lowpass equivalent linear filter and three stage interference canceller used for performance improvement. We show the performance results for number of canceller stage, diversity order and number of users and draw some conclusions that interference canceller is effective in multitone DS/CDMA system and the performance is further improved with the higher order of diversity and larger number of PN chips.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.4
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• pp.107-114
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• 2023

In this paper, the results of experiments conducted in indoor wired and outdoor wireless environments to reduce the interference impact of 5G mobile communication on fixed satellite services using RF Interference Reduction Module (IRM) are presented. Test results for interference signals with a 100MHz bandwidth in a wired environment demonstrate that RF IRM can reduce interference by more than 20dB in a 100MHz bandwidth. The performance of RF IRM was also tested in the S-band wireless environments. In the S-band wireless environments with interference signals having a 20MHz bandwidth, RF IRM exhibits interference reduction performance of 12-15dB, for signals with a 50MHz bandwidth, it shows 10-12dB interference reduction, and for signals with a 100MHz bandwidth, it demonstrates 5-10dB interference reduction. This paper shows that RF IRM can be used not only within transceivers but also in wireless environments to mitigate interference.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.9
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• pp.858-864
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• 2002

In this paper, Analyzed Performance of TH/UWB(Time Hopping/Ultra Wideband after Impulse Radio) system in interference environment by existing system that use same frequency band. In case interference fraction ratio is below 0.1, consider and analyzed in case influence through interference in IR system that is shared in 3.1 - 10.6 GHz band hereafter as case that use very small and narrow band than IR system such as 80 MHz bandwidth of ISM band or 802.1la's use bandwidth 20 MHz in 5 GHz band. According to result, we could know that Performance change according to possession band width of interference shows greatly than size of interference electric power. Also, interference fraction ratio is big (more than 0.1) narrowband interference in partial band interference environment, could get Performance improvement of big width increasing pulse repetition number. But, could know that do not influence hardly in system performance when interference fraction ratio is small (below 0.1) narrowband interference. Therefore, may receive the best system performance and transfer efficiency by set the most suitable pulse repetition number according to bandwidth fraction ratio of interference through correct interference fraction ratio estimation and apply proper interference suppression techniques.

• Journal of Advanced Navigation Technology
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• v.6 no.4
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• pp.318-325
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• 2002

In this paper, the effects of the interference environments on the performance of the time hopping(TH) binary PPM impulse radio(IR) system are presented. Based on the monocycle pulse available within the frequency of 3.1~10.6 GHz permitted for application by FCC, a PPM-modulated TH IR system simulator was designed and followed by the analysis of the monocycle pulse characteristics as well as the system performance. Particularly for the evaluation of the system performance, the multiple access interference and the narrowband system interference signals were considered as the interference signals. Since the narrowband system interference signal has very narrow bandwidth and very large amplitude compared with those of IR system, the analysis of the IR system performance was implemented by considering the interference power and band fraction ratio of the narrowband interference signal.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1234-1238
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• 2005

As the low power GPS signal is susceptible to interference, interference can seriously degrade the performance of GPS receiver. This paper designs a ANIEF(Adaptive Narrowband Interference Excision in Frequency domain) filter that removes narrow band interferences with low signal loss. This filter uses the pre-correlation technique and attempts to filter out the interference in the frequency domain. The interference excision performance of the designed filter is evaluated for various interferences using the ANIEF filter inserted GPS software receiver and the interference generator. Interferences considered in this paper are single-tone CWI(Continuous Wave Interference), multi-tones CWI, pulsed CWI, and swept CWI. The narrowband interference excision filter in frequency domain is very effective against various interferences and the strong interference with a simple structure. However, the signal power loss is unavoidable while transforming. In this paper, the hamming window and overlap technique are adopted to reduce the signal power loss. Finally, the interference excision performance and the reduced signal power loss of the ANIEF filter are shown.

• Journal of Electrical Engineering and information Science
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• v.3 no.1
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• pp.126-130
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• 1998

In this paper, a new interference rejection filter using the data-recycling technique is presented. The reference signal of the interference rejection filter is formed by using chip decisions, which is correlated with the narrowband interference components of the received signal. The decision feedback techniques reduce the distortion of the desired signal, which is introduced by the interference rejection filter through he use of feedback chip decisions. In order to update the filter coefficients a simple and efficient data-recycling technique that has improved performance over the conventional LMS algorithm is used. The performance of the proposed interference rejection filter is compared to filter with conventional LMS linear filter. The results show that the convergence speed of the proposed interference rejection filter using decision feedback and data-recycling technique is significantly faster than that of the conventional filters. Also, BER performance of the interference rejection filter demonstrates the superiority of the proposed filter algorithm.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.8
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• pp.10-19
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• 1997

In this paper, perfodrmance of matched-filter (MF) acquisition scheme is analyzed for a direct-sequence/code-division-multiple-access (DS/CDMA) system in a microcellular environment. Mean acquistion time is used as a performance measure. It is demonstrated that acquisition performance is enhanced using interference suppression filter in a Rician fading channel. To apply for multiuser environments, multiple access interference is considered in the performance analysis. From the numerical results, it is shown that mean acquistion time decreases with the increasing SNR/chip, and acquisition performance is improved as the number of taps of interference suppression filter. It is also shown that mean acquisition time increases with the number of users in the system, and acquistion performance is degraded as the icrease of narrowband interference bandwidth. The analysis in this paper can be applied to a DS/CDMA overlay environment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.2
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• pp.221-227
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• 2002

In this paper, in order to know the effect of the interference, we have analyzed the BER (Bit Error Rate) performance of the MUD(Multi-User Detector) employing HIC(Hybrid Interference Cancellation) scheme for the asynchronous WCDMA system based on 3GPP(3rd Generation Partnership Project) Spec. through the In this paper, in order to know the effect of the interference, we have analyzed the BER (Bit Error Rate) performance of the MUD(Multi-User Detector) employing HIC(Hybrid Interference Cancellation) scheme for the asynchronous WCDMA system based on 3GPP(3rd Generation Partnership Project) Spec. through the computer simulation. we have assumed Rayleigh fading channel. And we have compared its BER performance with SIC's(Successive Interference Cancellation) and with PIC's(Parallel Interference Cancellation), which are the representative schemes in the subtractive interference cancellation. From the results, it is shown that PlC or HIC is effective for high data-rate users and SIC of HIC for low data-rate users to eliminate the interference. Regardless of the data rate, it is reasonable to use the HIC structure for WCDMA system to satisfy all of users' services. The reason is that the SIC scheme in front of HIC can guarantee the performance of low power users to cancel the serious interference caused by the high power users, while PIC in the rear of it can guarantee the performance of high power users to cancel the interference caused by the low power users.

• KIISE Transactions on Computing Practices
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• v.22 no.9
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• pp.473-478
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• 2016

Server virtualization provides abstraction of physical resources to users and thus accomplishes high resource utilization and flexibility. However, the characteristics of server virtualization, such as the limited number of physical resources shared by virtual machines, can cause problems, mainly performance interference. The performance interference is caused by the fact that the CPU scheduler running on the host operating system schedules virtual machines without considering the characteristics of the virtual machine's internal process. To address performance interference, a number of research activities to improve performance interference have been conducted, but do not deal with the fundamental analysis of performance interference. In this paper, in order to analyze the cause of performance interference, we carry out profiling in a variety of scenarios in a virtualized environment based on KVM. As a result, we analyze the phenomenon of the performance interference in terms of CPU scheduling and propose an efficient scheduling solution.

• Journal of Communications and Networks
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• v.1 no.2
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• pp.118-133
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• 1999

In this paper we compare linear and non-linear inter-ference cancellation for systems employing code division multi-ple access (CDMA) techniques. Specifically, we examine linear and non-linear parallel interference cancellation(also called multi-stage cancellation) in relationship to other multiuser detection al-gorithms. We show the explicit relationship between parallel inter-ference cancellation and the decorrelator (or direct matrix inver-sion). This comparison gives insight into the performance of paral-lel interference cancellation (PIC) and leads to vetter approaches. We also show that non-linear PIC approaches with explicit chan-nel setimation can provide performance improvement over linear PIC, especially when using soft non-linear symbol estimates. The application of interference cancellation to non-linear modulation techniques is also presented along with a discussion on minimum mean-squared error(MMSE) symbol estimation techniques. These are shown to further improve the performance of parallel cancella-tion.