• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.138-141
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• 1999

New solutions are given for the capacity and spectrum efficiency of frequency hopped spread spectrum multiple access system(FH-SSMA) in a Nakagami interference environment. In this paper we derive a exact formulation of the deletion probability for a mobile environment and analyze the system capacity and spectrum efficiency in terms of the average bit error rate(BER). It is shown that the system capacity is decreased by 52% as the Nakagami fading parameter is reduced to 0.5 and the required signal to noise ratio(SNR) is above 25dB, to get the spectrum efficiency of 0.3.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.841-845
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• 1991

There are Carrier Current Communication or Power line Carrier (PLC) Communication conducted data exchange using power line Which is installed existing indoor. Power line is possible to construct data link economically, on the other hand, have an inferior transmission environment such as irregular noise and severe level variation. The purpose of this paper is to present transmission possibility for PLC using spread spectrum technique. In the initial synchronization, established computer simulation for the S/N in relation to PN code generator. By using this result, construct the prototype SS system and then experiment the transmission characteristics.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1998년도 학술발표대회 논문집 제17권 1호
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• pp.357-360
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• 1998

DS/CDMA system rejected narrow-band interference and additional White Gaussian noise which are occured at multipath, intentional jammer and multiuser to share same bandwidth in mobile communication systems. Because of having not sufficiently obtained processing gain which is related to system performance, they were not effectively suppressed. In this paper, an matched filter channel model using backpropagation neural network based on complex multilayer perceptron is presented for suppressing interference of narrow-band of direct sequence spread spectrum receiver in DS/CDMA mobile communication systems. Recursive least square backpropagation algorithm with backpropagation error is used for fast convergence and better performance in matched filter receiver scheme. According to signal noise ratio and transmission power ratio, computer simulation results show that bit error ratio of matched filter using backpropagation neural network improved than that of RAKE receiver of direct sequence spread spectrum considering of con-channel and narrow-band interference.

• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2005년도 6th 2005 International Conference on Computers, Communications and System
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• pp.187-190
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• 2005

Ultra wideband (UWB) technologies have been developed to exploit a new spectrum resource in substances and to realize ultra-high-speed communication, high precision geolocation, and other applications. The energy of UWB signal is extremely spread from near DC to a few GHz. This means that the interference between conventional narrowband systems and UWB systems is inevitable. However, the interference effects had not previously been studied from UWB wireless systems to conventional mobile wireless systems sharing the frequency bands such as WCDMA system. This paper experimentally evaluates the interference from two kinds of UWB sources, namely a direct-sequence spread-spectrum UWB source and an impulse radio UWB source, to a WCDMA digital transmission system. The average frame error rate degradations are presented. From these experimental results, we show that in all practical cases UWB system can coexist with WCDMA terminal without causing any dangerous interference.

• Journal of Communications and Networks
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• 제14권2호
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• pp.199-205
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• 2012

This work investigates the progressive linear precoder design for packet retransmissions in multi-input multi-output (MIMO) systems with multiple codewords and automatic repeat request (ARQ) bundling feedback. Assuming perfect channel state information, a novel progressive linear ARQ precoder is proposed in the perspective of minimizing the packet error rate. We devise the ARQ precoder by combining power loading and sub channel pairing between current retransmission and previous transmissions. Furthermore, we extend the design to the case that the channel estimation error exists. Numerical results show that the proposed scheme can improve the performance of MIMO ARQ systems significantly regardless of the channel estimation error.

• 한국통신학회논문지
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• 제12권2호
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• pp.115-123
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• 1987

종래의 스펙트럼 확산 통신방식은 비동기의 다중접속이 가능하다는 특징을 가지지만, 챈널간 간섭이 존재하기 때문에 동시 통신 가능한 챈널 수가 TDM 에 비해 작아, 주파수 이용 효율이 나쁘다. 이것을 개선하기 위해 본 논문에서는 새로운 변형 M계열을 확산 부호로 하는 동기식 스펙트럼 확산 다중 통신 방식을 제안한다. 시스템 구성후 실험결과 M계열 사용시보다 변형 M계열 사용시 챈널 간 간섭이 적음을 확인하였고 전송 대역폭이 클수록 수신파형이 양호함도 확인하였다.

• 대한전자공학회논문지
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• 제20권4호
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• pp.61-66
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• 1983

본 논문에서는 대역 확산 다중통신 시스템에 쓰이는 가상 잡음 시퀀스의 설계에 관하여 연구하였다. 구형파의 일반형인 새로운 파형을 제안하여 분석한 결과 파형푹이 줄어듬에 따라 다중통신간섭 (multiple access interfererlce)이 0으로 접근하였다. 이 두항은 구형파나 정형파에 비해 훨씬 좋은 특성을 나타낸다.

• 대한전자공학회논문지
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• 제21권2호
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• pp.13-18
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• 1984

확산 스펙트럼 통신방식의 tracking 과정에서 hold-in time 및 false loch를 벗어나는 시간의 확률분포를 연구하였다. 이것은 correlator회로의 dwell time과 threshold level을 결정하는데 도움이 된다. 구하고자 하는 이산확률함수에 대한 발생함수를 급수전개하고 해당되는 항들의 계수를 합하여 동기 유지 시간의 확률분포를 유도하였다. 그리하여 일반적인 시스템 파라미터들로 표현된 결과식을 구하였다.

• 한국통신학회:학술대회논문집
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• 한국통신학회 1982년도 추계학술발표회논문집
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• pp.56-58
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• 1982

New acquisition method in synchronization of the PN-modulated spread spectrum system is presented. Microprocessor is adopted for its flexibility and the hardware complexity when not used.

• 한국통신학회:학술대회논문집
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• 한국통신학회 1990년도 추계종합학술발표회논문집
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• pp.73-78
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• 1990