• 한국통신학회논문지
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• 제32권6A호
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• pp.588-599
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• 2007

This paper presents the coexistence issues between M-WiMAX TDD and WCDMA FDD systems. To improve the M-WiMAX system performance and to reduce the adjacent channel interference to WCDMA FDD system, transmit and receive beamforming techniques are applied in the base stations of M-WiMAX system. Furthermore, we propose an adjacent channel interference modeling methodology, which captures the effect of transmit beamforming on the adjacent channel interference. Besides, we verify the performance improvement in the uplink of WCDMA system due to the transmit beamforming in M-WiMAX downlink based on the proposed adjacent channel interference modeling methodology. We also verify the performance enhancement due to the receive beamforming in the uplink of M-WiMAX system through system level Monte Carlo simulations, considering random user position, the effect of shadowing and multi-path fading channel. Discussions on the gain of applying transmit and receive beamforming in M-WiMAX system comparing the case of SISO system are also included. Furthermore, we present the performance of cosited M-WiMAX and WCDMA systems, considering commercial deployment, additional channel filter at base stations and the effects of TxBF and RxBF.

• Journal of electromagnetic engineering and science
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• 제7권2호
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• pp.83-90
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• 2007

In this paper, the formulation of the protection ratio based upon a composite fade margin and availability is newly presented for the detailed planning of frequency coordination in the microwave relay system network, and computed results for co-channel and adjacent channel protection ratios are illustrated over an actual system with 6.2 GHz. It is shown that the protection ratio to assure a quality of service can be expressed in terms of the composite fade margin, noise-to-interference ratio, net filter discrimination, and system parameters. In addition, the net filter discrimination, depending upon the transmitter spectrum mask and the overall receiver filter characteristic, has been examined to investigate the effect of the adjacent channel protection ratio caused by the adjacent channel interference. Regarding simulated results for 6.2 GHz, 60 km, 64-QAM, and N/I=6 dB at the bit error rate of $10^{-6}$, composite fade margin and co-channel protection ratio yield 25.14 and 50.3 dB, respectively. Also, the net filter discrimination of 26.5 dB and the adjacent channel protection ratio of 23.8 dB are obtained at the first adjacent channel of 30 MHz. The proposed method provides some merits in view of a comprehensive and practical application with more detailed and various system parameters needed to access the criteria for making the proper frequency coordination.

• 전기학회논문지
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• 제58권2호
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• pp.248-255
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• 2009

We proposed a power line channel model. We adopted advantages of other power line channel models to calculate channel responses correctly and simply. Infinite geometric series reduced the calculation complexity of the multipath signal propagation. Description Matrices were also adopted to handle the network topology easily. It represents complex power line network precisely and simply. Newly proposed model considered the effect of the adjacent nodes to channel responses, which have been not considered so far. Several simulations were executed to verify the effect of the adjacent nodes. As a result we found out that it affected channel responses but its effect was limited within certain degree.

• Journal of electromagnetic engineering and science
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• 제6권2호
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• pp.103-109
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• 2006

This paper suggests an efficient and comprehensive algorithm of the protection ratio derivation and illustrates some calculated results applicable to the initial planning of frequency coordination in the fixed wireless access networks. The net filter discrimination associated with Tx spectrum mask and overall Rx filter characteristic has been also examined to show the effect of the adjacent channel interference. The calculations for co-channel and adjacent channel protection ratios are performed for the current microwave frequency band of 6.7 GHz including Tx spectrum mask and Rx filter response. According to results, fade margin and co-channel protection ratio reveal 41.4 and 75.2 dB, respectively, for 64-QAM and 60 km at BER $10^{-6}$. It is shown that the net filter discrimination with 40 MHz channel bandwidth provides 28.9 dB at the first adjacent channel, which yields 46.3 dB of adjacent channel protection ratio. In addition, the protection ratio of 38 GHz radio relay system is also reviewed for millimeter wave band applications. The proposed method gives some advantages of an easy and systematic extension for protection ratio calculation and is also applied to frequency coordination in fixed millimeter wave networks.

• 대한전자공학회논문지
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• 제25권5호
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• pp.473-481
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• 1988

In this paper, we investigated bit error probabilities of GMSK, which is known to be one of promising modulation techniques for a digital mobile radio, under various mobile radio environments.: AWGN, slow Rayleigh fading channel, co-channel interference and adjacent channel interference. We employed an MSK-type receiver for a coherent detection and assumed degrading to both signals than adjacent channel interference. Especially, it is found that GMSK suffers more degradations than MSK from the co-channel interference. But with a high power adjacent channel interference, GMSK shows less bit error rate than MSK. The results confirm a higher spectrum efficiency of GMSK.

• 한국전자파학회논문지
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• 제16권11호
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• pp.1138-1146
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• 2005

본 논문에서는 인접 채널 간섭 분석을 위한 통합 필터 변별도(NFD)의 수식과 계산을 고찰하며, 이를 근거로 고정 무선 중계망의 주파수 조정에 필요한 동일 채널 및 인접 채널 보호비 산출을 위한 체계적인 알고리즘을 제시한다. 인접 채널 보호비를 페이드 마진, 변조 방식, 허용 간섭의 함수로 표현된 동일 채널 보호비와 송신스펙트럼 마스크 및 수신기 필터 특성에 의존하는 NFD의 계산 결과로 구할 수 있음을 보인다. 실제 계산을 보이기 위해 6.2 및 6.7 GHz 대역의 29.65 및 40 MHz 채널 대역폭에 대한 각각의 스펙트럼 마스크와 수신기 필터 특성으로 NFD를 구하였다. 결과에 의하면 29.65 및 40 MHz 채널에 대한 첫 번째 인접 채널의 NFD는 각각 27.4 및 28.9 dB을 얻었다. 이러한 결과로부터 거리 60 km, 64-QAM에 대해 채널 대역폭 29.65 및 40 MHz의 인접 채널 보호비는 각각 47.5 및 46.3 dB이 됨을 알 수 있었다. 제안된 방법은 계산이 용이하고 체계적인 확장과 밀리미터 무선 중계망의 주파수 조정에도 적용되는 이점이 있다.

• 한국통신학회논문지
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• 제33권3A호
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• pp.269-276
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• 2008

In this paper, we analyze the M-WiMAX UL capacity limits under 2-Tier cell layout, considering the effects of random user position, path loss models, fading channel and adjacent channel interference from WCDMA system. In order to make the analysis approximate to the practical system capacity, we propose a MCS-based capacity analysis method considering the effects of PER requirement and the utilized MCS levels in M-WiMAX system. The proposed MCS-based method is validated through a system-level Monte Carlo simulation. Furthermore, a comparison between the conventional Shannon method and the proposed MCS-based method is presented and the optimum cell radius is suggested.

• 한국멀티미디어학회논문지
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• 제15권7호
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• pp.903-909
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• 2012

본 논문에서는 TV 주파수 대역내의 인접채널간 다른 통신 시스템들의 공존을 위한 공유 성능을 분석하였다. 간섭 송신기의 다양한 밀도와 전송출력에 따른 파라미터 성능 결과를 분석하였다. 각 시스템간의 간섭 영향을 고려하기 위해, 두 경우가 분석되었다. 첫째로, 간섭시스템이 WiBro, 희생시스템이 WLAN인 경우와 두 번째로 간섭원이 WLAN이고 희생원이 WiBro인 경우이다. 채널 환경으로는 자유공간모델, Extended Hata, IEEE 802.11 모델을 이용하였다. 분석된 다양한 공유시나리오에서의 상호 공존 결과는 향후 인접 주파수 환경에서 다양한 통신 프로토콜을 이용하는 무선기기에 대한 상호 공존 조건을 마련하는 기술개발에 활용할 수 있을 것이다.

• ETRI Journal
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• 제41권6호
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• pp.703-714
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• 2019

Many use cases have been presented on providing convenience and safety for vehicles employing wireless access in vehicular environments and long-term evolution communication technologies. As the 70-MHz bandwidth in the 5.9-GHz band is allocated as an intelligent transportation system (ITS) service, there exists the issue that vehicular communication systems should not interfere with each other during their usage. Numerous studies have been conducted on adjacent interfering channels, but there is insufficient research on vehicular communication systems in the ITS band. In this paper, we analyze the interference channel performance between communication systems using distribution functions. Two types of scenarios comprising adjacent channel interference are defined. In each scenario, a combination of an aggressor and victim network is categorized into four test cases. The minimum requirements and conditions to meet a 10% packet error rate are analyzed in terms of outage probability, packet error rate, and throughput for different transmission rates. This paper presents an adjacent channel interference ratio and communication coverage to obtain a satisfactory performance.

• 한국전자파학회논문지
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• 제25권5호
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• pp.542-547
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• 2014

1차 사용자(primary user)는 자신에게 할당된 대역을 사용하여 통신을 수행하는데, 이때 송신 신호의 전력은 대부분 해당 대역에 집중되어 있지만, 일부는 인접 대역으로 넘어간다. 이 때문에 인접 대역이 비어 있더라도 오경보율이 예상보다 크게 발생할 수가 있다. 이전 연구 중에 인접 대역 누설 현상이 스펙트럼 센싱에 미치는 영향을 분석한 것이 있지만, 이때 페이딩을 고려하지 않았다. 본 논문에서는 페이딩 채널 환경에서 인접 대역 누설이 에너지 기반 스펙트럼 센싱 성능에 미치는 영향을 검파 확률과 오경보 확률 측면에서 분석하고자 한다.