• 한국통신학회논문지
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• 제29권8C호
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• pp.1055-1061
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• 2004

본 논문에서는 H.264/AVC 엔트로피 부호화 방식에서 다중 부호어를 이용한 효율적인 동적 부호화 방법을 제안한다. H.264/AVC에서 사용된 Exp-Golomb 부호어는 정적 확률 분포 특성 때문에 (7)에서 제시한 일원화 구문요소의 심볼 분포를 충분히 반영하지 못한다. 그러나 본 논문에서 제시한 다중 부호어 들은 다양한 통계적 특성을 나타낸다. 따라서 주어진 동영상에 따라 일원화 구문 요소를 부호화하기 위해 다중 부호어 들을 선택적으로 사용하는 동적 부호화 방법이 제안된다. 실험 결과에서는 제안한 방식이 (7)방식에 비해 화질의 열화 없이 압축 효율의 우수성을 보여준다.

• 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.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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• pp.89-92
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• 2003

A geometrically uniform code in AWGN channel has strong symmetry properties such as a) the distance profiles form codewords On C to all other codewords are all the same, and b) all Voronoi regions of codewords in C have the same shape. Such properties make the word error probability of geometrically uniform codes be transparent to the transmitted codeword. In this paper, we extend the geometrically uniform codes in AWGN channel to the geometrical uniform codes in fading channel with multiple transmit antennas.

• Journal of information and communication convergence engineering
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• 제15권1호
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• pp.7-13
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• 2017

We consider a distributed estimation where many nodes remotely placed at known locations collect the measurements of the parameter of interest, quantize these measurements, and transmit the quantized data to a fusion node; this fusion node performs the parameter estimation. Noting that quantizers at nodes should operate in a non-regular framework where multiple codewords or quantization partitions can be mapped from a single measurement to improve the system performance, we propose a low-weight estimation algorithm that finds the most feasible combination of codewords. This combination is found by computing the weighted sum of the possible combinations whose weights are obtained by counting their occurrence in a learning process. Otherwise, tremendous complexity will be inevitable due to multiple codewords or partitions interpreted from non-regular quantized data. We conduct extensive experiments to demonstrate that the proposed algorithm provides a statistically significant performance gain with low complexity as compared to typical estimation techniques.

• ETRI Journal
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• 제43권3호
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• pp.471-482
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• 2021

Several code-division multiple access (CDMA)-based interconnect schemes have been recently proposed as alternatives to the conventional time-division multiplexing bus in multicore systems-on-chip. CDMA systems with a dynamic assignment of spreading codewords are particularly attractive because of their potential for higher bandwidth efficiency compared with the systems in which the codewords are statically assigned to processing elements. In this paper, we propose a novel distributed arbitration scheme for dynamic CDMA-bus-based systems, which solves the complexity and scalability issues associated with commonly used centralized arbitration schemes. The proposed arbitration unit is decomposed into multiple simple arbitration elements, which are connected in a ring. The arbitration ring implements a token-passing algorithm, which both resolves destination conflicts and assigns the codewords to processing elements. Simulation results show that the throughput reduction in an optimally configured dynamic CDMA bus due to arbitration-related overheads does not exceed 5%.

• 전기전자학회논문지
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• 제23권2호
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• pp.710-715
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• 2019

We consider parameter estimation in distributed systems in which measurements at local nodes are quantized in a non-regular manner, where multiple codewords are mapped into a single local measurement. For the system with non-regular quantization, to ensure a perfect independent encoding at local nodes, a local measurement can be encoded into a set of a great number of codewords which are transmitted to a fusion node where estimation is conducted with enormous computational cost due to the large cardinality of the sets. In this paper, we propose an efficient estimation technique that can handle the non-regular quantized data by efficiently finding the feasible combination of codewords without searching all of the possible combinations. We conduct experiments to show that the proposed estimation performs well with respect to previous novel techniques with a reasonable complexity.

• 한국통신학회논문지
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• 제29권9C호
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• pp.1244-1251
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• 2004

본 논문에서는 H.264/AVC 엔트로피 부호화 방식에서 다중 부호어를 이용한 효율적인 동적 부호화 방법을 제안한다. H.264/AVC 에서 사용된 Exp-Golomb 부호어는 정적 확률 분포 특성 때문에 [7]에서 제시한 일원화 구문요소의 심볼 분포를 충분히 반영하지 못 한다. 그러나 본 논문에서 제시한 다중 부호어들은 다양한 통계적 특성을 나다낸다. 따라서 주어진 동영상에 따라 일원화 구문 요소를 부호화하가 위해 다중 부호어들을 선택적으로 사용하는 통적 부호화 방법이 제안된다. 실험 결과에서는 제안한 방식이 [7] 방식에 비해 화질의 열화 없이 압축 효율의 우수성을 보여준다.

• Journal of Electrical Engineering and Technology
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• 제9권4호
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• pp.1411-1417
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• 2014

An MPEG-2 AAC Huffman decoding method based on the fixed length compacted codeword tables, where each codeword can contain multiple number of Huffman codes, was proposed. The proposed method enhances the searching efficiency by finding multiple symbols in a single search, i.e., a direct memory reading of the compacted codeword table. The memory usage is significantly saved by separately handling the Huffman codes that exceed the length of the compacted codewords. The trade-off relation between the computational complexity and the amount of memory usage was analytically derived to find the proper codeword length of the compacted codewords for the design of MPEG-2 AAC decoder. To validate the proposed algorithm, its performance was experimentally evaluated with an implemented MPEG-2 AAC decoder. The results showed that the computational complexity of the proposed method is reduced to 54% of that of the most up-to-date method.

• 방송공학회논문지
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• 제24권4호
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• pp.613-622
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• 2019

코드북을 이용하는 폐루프 MISO 시스템에서 시간 상관성을 이용한 차분 코드북 설계 방법을 제안한다. 단일계층 코드북의 코드워드 인자들은 위상 성운의 집합 중에서 선택된다. 기존의 코드워드 선택 식에서는 코드워드들을 구면의 캡들이라 가정하고 서로의 각도를 사인 법칙을 이용하여 구하였으나, 본 논문에서는 피타고라스 법칙을 이용하는 새로운 방법을 이용하여 계산식을 간소화 시키는 식을 제안한다. 그리고 선택되는 코드워드간의 상관 계수 즉, 위상차의 변화를 추적하여 2 개의 코드북 중에 최적의 코드북을 적응적으로 선택하는 방법을 제안한다. Monte-Carlo 컴퓨터 시뮬레이션을 통해 제안하는 코드북의 성능을 검증한다.

• ETRI Journal
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• 제33권3호
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• pp.374-381
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• 2011

A simple and effective compression method is proposed for multiple-scan testing. For a given test set, each test pattern is compressed from the view of slices. An encoding table exploiting seven types of frequently-occurring pattern is used. Compression is then achieved by mapping slice data into codewords. The decompression logic is small and easy to implement. It is also applicable to schemes adopting a single-scan chain. Experimental results show this method can achieve good compression effect.