• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.33-36
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• 2000

DS-CDMA (direct sequence-code division multiple access) 시스템에서 여러 사용자가 동일 주파수 대역을 공유함으로써 다중 접속 간섭 (multiple access interference; MAI)이 발생하고 시스템의 성능을 크게 제한한다. 이러한 다중 접속 간섭을 제거하여 전송 신호의 질을 높이고 용량을 증대시키는 중요한 신호 처리 기술 가운데 하나가 적응 간섭 억제 기술이다. 적응 간섭 억제 기술 가운데 CMA (constant modulus algorithm) 기반의 블라인드 적응 간섭 억제기는 훈련수열을 필요로 하지 않고 빠른 수렴을 통하여 간섭을 효과적으로 제거할 수 있으나, 다중 경로 환경에서 심벌간 간섭 (intersymbol interference; ISI)이 증대되어 기존의 적응 수신기보다 악화된 성능을 보인다. 본 논문에서는 CMA를 기반으로 훈련 수열 없이 빠른 수렴을 하며 MAI와 ISI를 효과적으로 제거하기 위한 다이버시티 결합기 구조의 적응 간섭 억제기를 제한한다. 다중 경로 페이딩 채널 환경에서 기존의 블라인드 적응간섭 억제기와의 성능 비교 결과, 제안된 방식이 다중경로에 의한 ISI의 영향을 효과적으로 제거하여 우수한 성능을 얻을 수 있음을 확인하였다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.4
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• pp.9-16
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• 2000

This paper shows the performance of a multiuser detection DS-CDMA receiver based on of the hybrid scheme of parallel interference cancellation (PIC) and successive interference cancellation (SIC). The proposed hybrid interference cancellation is presented and is compared with existing PIC, SIC and Hybrid It of other type schemes. The performance criteria used for comparison are complexity, delay and average bit error rate (BER) performance obtained by simulation in Rayleigh-fading channel (Jake's model) with additive white Gaussian noise (AWGN). In the proposed hybrid IC, the BER performance approximates the one of SIC and the delay is half of the SIC. And the number of cancellation of the hybrid It is reduced about a fourth.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.83-86
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• 2000

DS/CDMA 이동통신 환경에서 채널의 용량을 제한하는 가장 큰 요인은 다중 사용자 간섭 신호의 영향이다. 본 논문에서는 어레이 안테나와 적응 혼합 다중 사용자 검파기 구조 (MUD: Multi-User Detection)를 이용하여 이러한 문제를 제거한다. 어레이 안테나의 각각의 빔 형성기는 MUD에서 궤환되는 기준 신호를 이용하여 원하는 사용자의 방향으로 빔을 형성하고 간섭 신호 방향으로는 널을 형성하여 제거하게 된다. 수신 신호의 전력이 제어되지 못하여 원근 문제(near-far problem)가 발생할 경우, 제안한 MUD는 적응적으로 지배적인 상관 값에 대해서는 직렬형, 비슷한 크기의 신호들은 병렬형 간섭 제거기를 통하여 제거함으로써 기존의 고정형 간섭 제거기보다 우수한 성능을 나타내었다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.2
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• pp.56-63
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• 2003

We investigate some implementation factors that affect the performance of multi-rate parallel interference cancellers (PICs) for the international mobile telecommunications-2000 (IMT-2000) 3rd-generation partnership project (3GPP) system. We consider the simple multi-rate PIC [1,2] that can remove effectively multiple access interference (MAI) through block-based detection and sample-based cancellation in asynchronous user environments. The PIC structure has significantly lower complexity as compared with that of the existing scheme, especially as the number of users increases. We analyze the effects of timing error, oversampling rate, unsynchronized users and/or outer-cell interference, and the number of Quantization bits on the PIE performance through extensive computer simulations. The models for such factors and the optimum parameters are drawn. Finally, we evaluate the receiver complexities of the PIC receivers employing using the advanced removal scheme.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.12
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• pp.10-19
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• 2001

In this paper, we propose an effective but simple multi-rate parallel interference canceller(PIC) for the international mobile telecommunications-2000(IMT-2000) 3rd generation partnership project (3GPP) system. For effective multi-rate processing, we define the basic block as one symbol period of the dedicated physical control channel(DPCCH) having the lowest data rate and common to all users. Then, decision and interference cancellation are performed at every basic block. For an asynchronous channel, we propose an advance removal scheme that removes in advance multiple access interference(MAI) due to the next blockof other users with shorter delay. Introducing a pipeline structure at a sample base, we can implement efficiently the PIC using the advance removal scheme with a minimum hardware and no extra computations. Through computer simulations, we analyze the bit error rate(BER) performance of the proposed PIC with respect to signal-to-noise ratio(SNR) and the number of users.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.1
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• pp.55-62
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• 1983

The error rate performance of phase shift Keyed(PSK) signal has been evaluated in terms of carrier-to-noise ratio(CNR), carrier-to-interferer ratio(CIR), impulsive index, and the phase difference between signal and interferer in the environment of cochannel PSK inter-ference and impulsive noise. We hays derived a general equation of the probability density function (p.d.f.) of output of coherent phase detector. And the error rate of the received binary PSK(BPSK) signal has been numerically evaluated. The graphic results show us that the best case is the situation of the signal and the inter- ferer meet with orthogonal phase.

• Journal of Aerospace System Engineering
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• v.17 no.5
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• pp.42-57
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• 2023

In this paper, to increase the research capability of flight missions and maintenance in operating military aircraft, we studied the requirements for additional mounting of flight video and data recorders and safety verification methods. The verification process of the recorder equipment itself, structural safety in the aircraft system, power and electrical safety, electromagnetic compatibility, and impact of airworthiness are described in accordance with military standards and operating environment requirements. In addition, through ground/flight tests, the results of functional operation suitable for the influence and demand of interference between the flight video and data recorder and other systems are also presented.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.963-966
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• 2000

현재 상용화된 CDMA (code division multiple access)방식은 사용자가 증가함에 따라 다중 사용자 간섭(multiuser interference)에 의해 통화품질 향상 및 가입자 수용 용량 증대에 한계를 가지고 있다. 이러한 문제를 극복하기 위해 다양한 다중 사용자 간섭 제거 알고리즘이 제안되었다 〔1-5〕. 본 논문에서는 여러 형태의 알고리즘들 가운데, 역상관 successive interference cancellation(SIC) , zero-forcing decision-feedback(ZF-DF) 검파기와 parallel interference cancellation(PIC) 검파기를 하이브리드 형태로 구성하는 방법을 제안하였고. 그에 따른 성능 분석 및 Rayleigh 페이딩 환경에서 컴퓨터 시뮬레이션을 통한 성능비교를 하였다. 컴퓨터 모의시험결과, 본 논문에서 제안한 3가지 하이브리드 검파기 모두 기존 검파기에 비하여 우수한 성능을 보였다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.3
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• pp.37-46
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• 2012

In RADAR and SONAR detection systems, noise environment can be classified into homogeneous and heterogeneous environment. Especially heterogeneous environments are modelled as target masking and clutter edge. Since the variability-index (VI) CFAR, a composed CFAR algorithm, dynamically selects one of the mean-level algorithms based on the VI and the MR (mean ratio) test, it is robust to various environments. However, the VI CFAR still suffers from lowered detection probabilities in heterogeneous environments. To overcome these problems, we propose an improved VI CFAR processor where TM (trimmed mean) CFAR and a sub-windowing technique are introduced to minimize the degradation of the detection probabilities appeared in heterogeneous environments. Computer simulation results show that the proposed method has the better performance in terms of detection probability and false alarm probability compared to the VI CFAR and single CFAR algorithms.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.89-94
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• 2009

A transceiver employing layered modulation encodes two data layers with different levels of robustness and selectively decodes one or both of them regarding the reception conditions. Because of the inconsistency in encoding and decoding, conventional ordered successive interference cancellation (OSIC) can not be compatible. In this letter, we derive a dualistic OSIC architecture, which assigns distinct criteria for demodulation and interference cancellation (IC). The proposed system achieves a higher spectral efficiency while guaranteeing reliable communication.