• 인터넷정보학회논문지
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• 제2권3호
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• pp.27-36
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• 2001

Recently much attention has been paid for interference mitigation technique for the COMA system, since more capacity is available with same bandwidth. In this paper, we introduces a novel adaptive interference suppression techniques for the CDMA system with narrow band interference. The proposed interference rejection scheme employs the adaptive linear prediction techniques in the subband. In each subband, we can more easily find and cancel the narrow band signal as compared to the full band. Thus, the proposed interference rejection can be classified as another time-frequency techniques for the narrow band interference rejection(10). Computer simulation is conducted for the 3-G COMA system with IF band sampling techniques, yielding better interference rejection and bit error rate performance as compared to conventional one. Also, optimum filter is analyzed and from the analysis, it can be shown the subband prediction techniques can suppress narrow band interference more efficiently.

• 한국전자파학회논문지
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• 제13권9호
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• pp.858-864
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• 2002

본 논문에서는 동일 주파수 대역을 사용하는 기존 시스템에 의한 간섭 환경에서 TH/UWB(Time Hopping/ Ultra Wideband 이하 Impulse Radio) 시스템의 성능을 분석하였다. 간섭 점유율이 0.1 이하인 경우는 5 GHz 대역에서 ISM 대역의 80 MHz 대역폭이나 802.113의 사용대역폭 20 MHz와 같은 IR 시스템에 비해 매우 협소한 대역을 사용하는 경우로써 향후 3.1 - 10.6 GHz 대역에서 공유되는 IR 시스템에서 간섭으로 영향을 미칠 경우를 상정하여 분석하였다. 결과에 의하면, 간섭 전력의 크기보다는 간섭의 점유 대역폭에 따라서 성능 변화가 크게 나타남을 알 수 있었다. 또한, 부분대역 간섭 환경에서는 펄스반복개수(Ns)를 증가시킴으로써 간섭 점유율이 큰(0.1이상) 협대역 간섭일수록 큰 폭의 성능 개선을 얻을 수 있었다. 그러나, 간섭 점유율이 적은(0.1이하) 협대역 간섭일 때는 시스템 성능에 거의 영향을 미치지 않음을 알 수 있었다. 따라서, 정확한 간섭 점유율 추정을 통해 간섭의 대역폭 점유율에 따라 최적의 펄스반복개수를 설정하고 적정한 간섭억압기법을 적용함으로써 최상의 시스템 성능 및 전송효율을 얻을 수 있을 것이다.

• Journal of electromagnetic engineering and science
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• 제9권4호
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• pp.182-187
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• 2009

When we assign frequency resources to a new radio service, the existing services need not to be interfered with by the new service. Therefore, when we make a frequency assignment, a guard band is necessary to separate adjacent frequency bands so that both can transmit simultaneously without interfering with each other. In this paper, we propose an efficient frequency guard band decision rule for avoiding interference between radio services. The guard band is established based on the probability of interference in the previously arranged scenario. The interference probability is calculated using the spectrum engineering advanced Monte Carlo(MC) analysis tool(SEAMCAT). After applying the proposed algorithm to set up the frequency guard band, we can decide on the guard band appropriately because the result satisfies the predefined criterion.

• 전기전자학회논문지
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• 제24권4호
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• pp.1028-1033
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• 2020

기존의 동일대역 간섭저감 방법은 무선기기 사이에 물리적인 이격거리를 지정하는 것으로 이격거리를 통해서 간섭을 억제한다. 만약 무선기기에서 동일대역 간섭을 저감할 수 있다면 물리적인 이격거리에 마진을 줄 수 있고, 수신기의 동작영역을 확장시키는 효과가 있으므로 간섭 대응 및 개선에 활용도가 크다. 본 논문에서는 동일대역 아날로그 간섭저감기의 구조를 제안하였고, 제안한 아날로그 간섭저감기의 설계와 구현에 대해서 기술하였다. 아날로그 간섭저감기를 설계하기 위해서 아날로그 간섭저감기의 성능에 영향을 미치는 지연(delay) 불일치, 위상오차 그리고 지연선로의 수에 따른 간섭저감 성능을 시뮬레이션 하였다. 16개의 지연선로로 구성된 아날로그 간섭저감기를 제작하였으며, 구현한 간섭저감기는 3.32㎓의 중심주파수에서 40MHz 대역폭을 갖는 5G(NR-FR1-TM-1.1) 신호에 대해서 약 10dB의 간섭저감 성능을 갖는다. 본 논문에서 제안한 아날로그 간섭저감기는 동일대역 간섭저감기로 활용가능하다.

• 정보통신설비학회논문지
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• 제8권1호
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• pp.18-23
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• 2009

The conventional channel selection method for a ZigBee communication network basically detects the energy values in all channels. In the ISM band, no license is required to use channels in this band, so there may exist various interference factors in this band. It is well known that WLAN is the major interference factor degrading the performance of ZigBee in the ISM band. In this paper, we propose an efficient channel selection algorithm which uses the pattern of two types of WLAN channel uses as the a priori information of IEEE 802.11 band IEEE 802.11g. By using the proposed algorithm, we may save the time required to select channels for the ZigBee communications.

• International journal of advanced smart convergence
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• 제11권3호
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• pp.28-35
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• 2022

Interference always exists between wireless communication systems used in the same frequency band or adjacent frequency bands. In order to deploy a new wireless communication system such as a 5G system, a new frequency band must be allocated to the system. For this purpose, after analyzing interference between the existing system and the new system, a method of setting a frequency guard band or a minimum separation distance has been used as a passive method to limit the interference effect. This paper presents a wideband RF IRM(Interference Reduction Module) that can actively reduce the influence of interference between wireless communication systems. The wideband RF IRM can reduce the interference effects of 5G signals on satellite signals. The principle and structure of the wideband RF IRM are presented. The wideband RF IRM can suppress approximately 20dB of interference signal in 100MHz bandwidth when only interference signal exists. It also shows that when a 5G interference signal of -45dBm/100MHz and a satellite signal of -55dBm/40MHz exist simultaneously at a center frequency of 3.83GHz, about 15dB of 5G interference signal can be reduced in the frequency range covered by the satellite signal. The experimental results demonstrate that the wideband RF IRM can actively reduce the 5G interference signal on the satellite signal and can be used for the purpose of reducing the interference effect in a similar environment.

• Journal of electromagnetic engineering and science
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• 제18권4호
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• pp.254-260
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• 2018

In this study, we suggest an emulator for generating multiple heterogeneous interference signals in the Korean radio frequency identification/ubiquitous sensor network (RFID/USN) frequency band. The proposed emulator uses only one universal software radio peripheral to generate multiple heterogeneous interference signals more economically. Moreover, the physical and media access control parameters can be adjusted in real time using the LabVIEW program, thereby making it possible to create various time-varying interference environments easily. As an example showing the capability of the proposed emulator, multiple interference signals consisting of a frequency-hopping RFID signal and two LoRa signals with different spreading factors were generated. The generated signals were confirmed in both frequency and time domains. From the experimental results, we verified that our emulator could successfully generate multiple heterogeneous interference signals with different frequency and time domain characteristics.

• Journal of Communications and Networks
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• 제10권1호
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• pp.63-70
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• 2008

Narrow-band interference (NBI) from the coexisting narrow-band services affects the performance of ultra wideband (UWB) systems considerably due to the high power of these narrow-band signals with respect to the UWB signals. Specifically, IEEE 802.11a systems which operate around 5 GHz and overlap the band of UWB signals may interfere with UWB systems significantly. In this paper, we suggest a novel NBI suppression technique based on singular value decomposition (SVD) algorithm in time hopping UWB (TH-UWB) systems. SVD is used to approximate the interference which then is subtracted from the received signals. The algorithm precision and closed-form bit error rate (BER) expression are derived in the wireless multipath channel. Comparing with the conventional suppression methods such as a notch filter and a RAKE receiver, the proposed method is simple and robust and especially suitable for UWB systems.

• ETRI Journal
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• 제39권6호
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• pp.771-781
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• 2017

For efficient spectral utilization of satellite channels, a shared band transmission technique is introduced in this paper. A satellite transmits multiple received signals from a gateway and terminal in the common frequency band by superimposing the signals. To improve the power efficiency as well as the spectral efficiency, a travelling wave tube amplifier in the satellite should operate near the saturation level. This causes a nonlinear distortion of the superimposed transmit signal. Without mitigating this nonlinear effect, the self-interference cannot be properly cancelled and the desired signal cannot be demodulated. Therefore, an adaptive compensation scheme for nonlinearity is herein proposed with the proper operation scenario. It is shown through simulations that the proposed shared band transmission approach with nonlinear compensation and self-interference cancellation can achieve an acceptable system performance in nonlinear satellite channels.

• International Journal of Internet, Broadcasting and Communication
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• 제15권4호
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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.