• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송∙미디어공학회 2017년도 하계학술대회
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• pp.49-51
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• 2017

본 논문에서는 ATSC 3.0 시스템의 2x2 MIMO (multiple input multiple output) 방식을 적용한 송수신기 구조에 대해서 살펴본다. ATSC 3.0 시스템의 MIMO 에서 적용된 프리코더 (precoder)는 스트림 결합기(stream combining), IQ 편파 인터리빙 (I/Q polarization interleaving), 위상 홉핑부 (phase hopping)로 구성된다. 또한, ATSC 3.0 의 2x2 MIMO 방식을 사용함으로써 공간 다중화 (spatial multiplexing) 이득과 공간 다이버시티 (spatial diversity) 이득을 얻을 수 있다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.277-280
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• 1998

The paper provides an overview of those requirements. A detailed description is given of the construction of the new channel code, called 24/25 code, that compiles with the given constraints and involves only a minor drawback in terms of the overhead needs. The servo position information is recorded as low frequency componets, pilot tracking tones, which are embedded in the recorded stream of binary digits. Pilot tracking Tones are used to derive head position reference information in camcorders and DVCRs. A simple pilot tone encoder has been designed by using a new approach, "2 path precoder". Owing to this method, the hardware size can be significantly reduced. the correctness of the method has been verified by theoretical analysis and by extensive simulation.imulation.

• 한국통신학회논문지
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• 제35권11A호
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• pp.1045-1050
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• 2010

본 논문에서는 기존의 공간 다중화(Spatial-Multiplexing, SM) 기법과 직교 선부호기를 직렬 연접한 새로운 $2{\times}2$ SM 기법을 제안한다. 실험 결과 제안된 기법은 기존의 SM과 비교하여 erasure가 발생하지 않는 채널 환경에서는 기존의 SM과 동일한 성능을 가지면서 erasure 채널 환경에서는 큰 성능 향상이 발생한다. 특히 수신 안테나들 사이에 상관 값이 커질 경우 더 큰 성능 향상이 발생한다.

• 한국통신학회논문지
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• 제35권3A호
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• pp.260-268
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• 2010

Channel inversion is one of the simplest techniques for multiuser downlink systems with single-antenna users. In this paper, we extend the regularized channel inversion technique developed for the single-antenna user case to multiuser multiple-input multiple-output (MIMO) channels with multiple-antenna users. We first employ the multiuser preprocessing to project the multiuser signals near the null space of the unintended users based on the MMSE criterion, and then the single-user preprocessing is applied to the decomposed MIMO interference channels. In order to reduce the complexity, we focus on non-iterative solutions for the multiuser transmit beamforming and use a linear receiver based on an MMSE criterion. Simulation results show that the proposed scheme outperforms existing joint iterative algorithms in most multiuser configurations.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2012년도 하계학술대회
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• pp.188-191
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• 2012

단일 주파수 방송 시스템에서 이레이저 현상이 생길 경우 기존의 공간 다중화 기법은 큰 성능 저하가 발생한다. 이에 본 논문에서는 라이시안 이레이저 페이딩 채널 환경에서 기존의 $2{\times}2$ 공간 다중화 기법에 직교 선부호기를 직렬 연접한 공간 다중화 기법의 성능을 분석하고, 수신 SER 성능을 최대화하는 선부호기 최적화를 수행한다. 전산 실험 결과, Rician 이레이저 페이딩 채널 환경에서 최적의 선부호화 공간 다중화 기법은 수신단에서 성상 모호성을 줄여 기존의 공간 다중화 기법에 비하여 우수한 성능 향상을 보였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 통신소사이어티 추계학술대회논문집
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• pp.7-10
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• 2003

VDSL(Very-high-rate Digital subscriber Line) have a severe FEXT(Far-End Crosstalk). This paper proposes FEXT cancelation scheme in VDSL system. The scheme is GDFE(Generalize Decision Feedback Equalizer) and Vectored-DMT (Discrete Multitone). Feedback part of GDFE decreases FEXT noise. Canceler and Precoder block a part of Vectored-DMT eliminate FEXT. After all, simulation result show improvement of transmit and receive speed.

• Journal of Communications and Networks
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• 제13권1호
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• pp.63-69
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• 2011

In this paper, we propose a fixed-complexity sphere encoder (FSE) for multi-user multi-input multi-output (MU-MIMO) systems. The proposed FSE accomplishes a scalable tradeoff between performance and complexity. Also, because it has a parallel tree-search structure, the proposed encoder can be easily pipelined, leading to a tremendous reduction in the precoding latency. The complexity of the proposed encoder is also analyzed, and we propose two techniques that reduce it. Simulation and analytical results demonstrate that in a $4{\times}4$ MU-MIMO system, the proposed FSE requires only 11.5% of the computational complexity needed by the conventional QR decomposition with M-algorithm encoder (QRDM-E). Also, the encoding throughput of the proposed encoder is 7.5 times that of the QRDM-E with tolerable degradation in the BER performance, while achieving the optimum diversity order.

• ETRI Journal
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• 제33권6호
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• pp.831-840
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• 2011

This paper focuses on codebook-based precoding for space-division multiple access/orthogonal frequency-division multiple access (SDMA-OFDMA) systems aiming to guarantee high throughput for their users as well as to mitigate interference to fixed satellite service (FSS). A systematic design of SDMA codebook for subband-based OFDMA is proposed, which forms multiple orthogonal beams with common spatial null in the direction of a victim FSS earth station (ES). The design enables both transmitter and receiver to independently construct identical codebook by sharing only on the direction angle of an FSS ES, which takes fewer overhead bits than Gram-Schmidt process, a general method satisfying our design criterion. A system-level throughput evaluation shows that the proposed precoding provides superior performance over existing spectrum sharing method, that is, subband deactivation. The spectrum sharing analysis shows that the proposed precoding, even with an estimation error of the direction angles of an FSS ES, causes lower interference than existing precoding, knockdown precoding.

• 한국통신학회논문지
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• 제40권1호
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• pp.58-60
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• 2015

본 논문은 송신 상관 MIMO 채널에서 SM 시스템의 성능 열화를 극복하는 개루프 프리코딩 기법을 제안한다. 제안 기법은 성상도의 최소거리를 최대화 하는 프리코딩의 피드백 오류에 따른 성능 분석을 통해 제시하였고, 제안한 프리코딩 기법은 수신기로부터 채널 정보의 피드백 없이 성능 열화를 줄일 수 있다.

• Journal of Communications and Networks
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• 제4권3호
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• pp.189-198
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• 2002

Precoder has been shown to be able to provide source diversity and design flexibility. In this paper we employ precoding techniques for block transmission based on a multirate filterbank structure. To accommodate multiuser communication with variable data rates, different precoders with corresponding coefficients and up/down sampling rates are used. However, due to unknown multipath distortion, different interferences may exist in the received data, such as multiuser interference, intersymbol interference and interblock interference. To estimate channel parameters for a desired user, we employ all structured signature waveforms associated with different symbols of that user and apply subspace techniques. Therefore better performance of channel estimator can be achieved than the conventional subspace method based only on the signature of the current symbol. The delay for that user can also be jointly estimated. Channel identifiability conditions and asymptotic channel estimation error are investigated in detail. Numerical examples are provided to justify the proposed method. gest either multicode (MC) or multiple processing gain (MPG) mechanism [2], while requiring data rates to be integral multiples of some basic low-rate. In order to support variable rate transmission however, a comprehensive scheme needs to be investigated.