• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권12호
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• pp.2315-2325
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• 2011

We propose a novel reduced-state maximum-likelihood sequence detection (MLSD) structure using the Viterbi algorithm based on the second-order Volterra kernel modeling nonlinear distortion due to square law detection of multipath channels commonly occurring in chromatic dispersion (CD) or polarization mode dispersion (PMD) in optical communication systems. While all existing MLSD methods for square-law detection receivers are based on direct computation of branch metrics, the proposed algorithm provides an efficient and structured way to implement reduced-state MLSD with almost the same complexity of a MLSD for linear channels. As a result, the proposed algorithm reduces the number of parameters to be estimated and the complexity of computation.

• 전자공학회논문지B
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• 제33B권11호
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• pp.83-96
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• 1996

On PR-IV magnetic recording systems, the maximum likelihood sequence detection (MLSD) method is optimum. But it has the problem of the complexity of the structure. The three level detection (TLD) method can be used, which has simpler structure than MLSD, but requires almost twice of power to achieve the same probbility of error as MLSD does. Therefore a new detection method (error controlled detection: ECD) is proposed which has much simpler structure than MLSD and gives much better performance than TLD. The simulation resutls show that the performance of ECD is better than that of TLD by approximaterly 0.5~1.3dB both in linear and nonlinear channels.

• 한국통신학회논문지
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• 제21권6호
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• pp.1522-1532
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• 1996

In this paper, we compare the performance of channel estimators with the L$_{1}$-norm and L$_{2}$-norm criteria in impulaive noise environment, and show than the L$_{1}$-norm criterion is appropriate for that situation. Also, it is shown that the performance of the conventional maximum likelihood sequence detector(MLSD) can be improved by applying the same principle to mobile channels. That is, the performance of the conventional MLSD, which is known to be optimal under the Gaussian noise assumption, degrades in the impulsive noise of radio mobile communication channels. So, we proposed the MLSD which can reduce the effect of impulsive noise effectively by applying the results of channel estimators. Finally, it is confirmed by computer simulation that the performance of MLSD is significantly affected depending on the types of branch metrics, and that, in the impulsive noise environments, the proposed one with new branch metrics performs better thatn the conventional branch metric, l y(k)-s(k) l$^{[-992]}$ .

• 한국전자파학회논문지
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• 제9권6호
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• pp.746-760
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• 1998

본 논문에서는 이동 위성 채널에서 트렐리스 부호화된 CPFSK 신호를 검파하는데 있어서 최적의 수신 방식인 MLSD 대신에 복잡도를 크게 줄이면서 MLSD와 거의 같은 성능을 얻는 적응 RSSD 수신 방식을 제안 한다. 제안된 앉줬D를 시변 채널인 이동 위성 채널에 적용하기 위해서는 채널의 상태를 추정해야 하는 문제 가 발생하며l 본 논문에서는 채널의 특성을 추정하는 방법으로 steepest desc에t 알고리틈을 이용하며I 보다 효율적인 채널 추정을 위해 symbol-aided방법이 사용된다. syr뼈ol-aided 방법은 신뢰성 있는 채널 추정을 위하여 송신단에서는 주기적으로 알고 있는 섬볼을 삽입한 후에, 수신단에서는 알고 있는 섬볼이 수신되면 비터비 프로세서는 임시 데이터 결정을 하여 채널 추정기로 보내는 방법이다. 이러한 임시 데이터 결정 방법 을 사용한 채널 추정기는 긴 결정 지연 시간올 이용한 방법보다도 이동 위성 채널에서 빠르고 신뢰성 있게 채널을 추정한다. 본 논문에서 제안한 적웅 RSSD 수신 방식은 적웅 MLSD에 대한 준최적 수신 방식임에도 불구하고 복잡도를 크게 줄이면서 이통 위성 채널을 빠르고 신뢰성 있게 추적한다.

• 한국통신학회논문지
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• 제29권6A호
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• pp.683-689
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• 2004

The power and bandwidth efficient constant-envelope BPSK (CE-BPSK) modulation is proposed. The CE-BPSK signal is realized specifying the phase transition characteristics for the conventional low pass filtered BPSK signal. Since the CE-BPSK signal has constant envelope and modified waveform, the CE-BPSK signal has better power and bandwidth efficiency compared to the conventional BPSK signal while the CE-BPSK signal is backward compatible to the conventional BPSK signal. It is also shown that the bit error rate performance of the CE-BPSK signal is the same as that of the conventional BPSK signal.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.279-280
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• 2008

In order to improve the performance and simplify the structure of the conventional detectors in high density magnetic channels, a new equalizer based on bilinear recursive polynomial (BRP) models, which uses the previously estimated sequence, is proposed. The performance is compared with the conventional equalizers and the maximum likelihood sequence detection (MLSD) bound.