• 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.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.125-130
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• 2005

This paper suggests an efficient method of protection ratio calculation and shows some calculated results applicable to frequency coordination in microwave relay system networks, and the net filter discrimination (NFD) associated with Tx spectrum mask and overall Rx filter characteristics has been examined to obtain the adjacent channel protection ratio. The protection ratio comprises several factors such as C/N of modulation scheme, noise-to-interference ratio, multiple interference allowance, fade margins of multi-path and rain attenuation, and NFD. According to computed results for 6.7 GHz, 64-QAM, and 60 km at BER $10^{-6}$, fade margin and co-channel protection ratio are 41.1 and 75.2 dB, respectively, In addition, NFD for channel bandwidth of 40 MHz reveals 28.9 dB at the first adjacent channel, which results in adjacent channel protection ratio of 46.3 dB. The proposed method provides some merits of an easy calculation, systematic extension, and applying the same concept to frequency coordination in millimeter wave relay system networks.

• 한국통신학회논문지
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• 제29권2A호
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• pp.166-173
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• 2004

위성 통신 시스템은 지상국과 위성에서 고출력의 비선형 HPA(high power amplifiers)를 사용하게 된다. 그러므로 HPA의 비선형성이 통신 시스템에 미치는 영향을 고려하는 것이 중요하다. 본 연구는 비선형성 HPA에 의한 전력 스펙트럼 밀도 변화와 IBO(input back-off)에 따라 신호의 왜곡과 하모닉 성분의 크기 변화를 구한다. 그리고 BPSK 위성 통신 시스템에서, HPA에 의한 인접 채널 간섭(ACI : adjacent channel interference) 및 외부 재밍 간섭 등에 의한 동일채널 간섭(CCI : co-channel interference)를 고려하여 성능분석을 한다. 일정한 uplink SNR(signal to noise power ratio), uplink SIR(signal to co-channel interference power ratio), downlink SIR인 상황에서, 인접 채널 간섭의 크기에 따른 BER 성능 변화를 구한다. 위성에만 비선형 HPA가 있을 경우는, 비선형에 의한 인접 채널 간섭의 크기에 따라 성능에 많은 차이가 있음을 확인하였다. 그리고 지상국과 위성에서 모두 비선형 왜곡이 있을 때, CCI와 인접 채널 간섭에 의하여 더욱 성능이 저하된다.

• 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.

• 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.

• Journal of electromagnetic engineering and science
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• 제6권3호
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• pp.189-195
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• 2006

In this paper, the derivation of the protection ratio for the digital microwave system with diversity is newly suggested for a basic guidance of initial planning for frequency coordination, and computational results are presented for an actual radio frequency band. The net filter discrimination has been also examined to see the effect of the adjacent channel protection ratio caused by adjacent channel interference. In addition, the protection ratios for the space or frequency diversity system are analyzed in terms of diversity improvement factors to find out an equivalent allowable noise-to-interference ratio (N/I) from degraded fade margin. According to results for 6.2 GHz system, with the space diversity of 25 m distance between antennas or the frequency diversity of ${\Delta}f/f=0.05$, under 64-QAM and 60 km at BER $10^{-6}$, the protection ratio can be greatly reduced in comparison to the non-diversity system. So, assuming that only the same protection ratio as the non-diversity system is kept, it is shown that the system with diversity may get more interference level of N/I allowing from 9.0 to - 5.9 dB or from 6.0 to - 4.3 dB for the space or frequency diversity. In consequence, it is concluded that the diversity system is more robust or tolerable for interferences or fades, which may play an important role in overcoming N/I to some extent.

• 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.

• Journal of Communications and Networks
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• 제10권2호
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• pp.127-136
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• 2008

For mobile wireless systems with full frequency reuse, co-channel interference near the cell coverage boundaries has a significant impact on the signal reception performance. This paper addresses an approach to efficiently mitigate the effect of downlink co-channel interference when multi-antenna terminals are used in cellular environments, by proposing a signal detection strategy combined with a system-level coordination for dynamic frequency reuse. We demonstrate the utilization of multi-antennas to perform spatial demultiplexing of both the desired signal and interfering signals from adjacent cells results in significant improvement of spectral efficiency compared to the maximal ratio combining (MRC) performance, especially when an appropriate frequency reuse based on the traffic loading condition is coordinated among cells. Both analytic expressions for the capacity and experimental results using the adaptive modulation and coding (AMC) are used to confirm the performance gain. The robustness of the proposed scheme against varying operational conditions such as the channel estimation error and shadowing effects are also verified by simulation results.

• 한국항행학회논문지
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• 제16권2호
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• pp.219-226
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• 2012

3GPP의 LTE/LTE-Advanced 시스템은 OFDM(Orthogonal Frequency Division Multiplexing) 기술적용으로 주파수 할당에 의한 간섭분석 및 주파수 공유평가가 중요하다. 이에 본 논문에서는 LTE 두 사업자/시스템간의 인접채널 간섭 분석에 의한 주파수 공유연구를 수행하였다. 업링크 및 다운링크에서의 시스템 용량 및 스루풋(throughput) 손실에 대한 시뮬레이션 분석이 이루어져 5% 손실율의 주파수 공유기준으로 요구되는 ACIR(Adjacent Channel Interference Ratio) 값을 정의하였다. 유저(user)의 위치, 간섭 대역폭, 시스템 분리 옵셋(separation offset) 등의 파라미터들에 의해 주파수 공유를 위해 요구되는 ACIR 값에 미치는 영향이 분석되었으며, 이러한 결과 데이터 및 간섭분석 방법들은 향후 LTE RF 표준 및 주파수 유효이용에 참고자료로 활용될 것이다.

• 대한전자공학회논문지
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• 제15권6호
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• pp.29-34
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• 1978

아나로그 무선통신계와 디지탈 무선통신계가 각기 동일 무선주파수대의 인접주파수를 사용함에 의한 시스템간 간섭이 존재하는 상태하에서 이들 양 무선통신계가 혼재하기 위해 필요한 최적조건을 구하고자 그의 제일단계로서 아나로그계가 디지탈계에 미치는 시스템간 간섭에 대해 이론적 해석을 행했다. 이에는 특히 이제까지 불분명했던 PSK 신호에 미치는 FM 신호의 간섭영향에 대해서 논했다. 본 연구에서 얻어진 결과는 시스템간 간섭의 존재하에 있어서의 PSK 시스템에 대한 각파수할당 및 대역폭, 전력 등을 정함에 있어 유효한 자료를 제공한다.