다중 셀 MIMO 네트워크를 위한 Hadamard 행렬 Interstream 전송 기반 Blind 채널 추정

양재승,모하마드 아부 하니프,박주용,이문호 한국인터넷방송통신학회 2015 한국인터넷방송통신학회 논문지 Vol.15 No.4

본 논문에서는 다중 셀 MIMO (multiple-input and multiple-output) 네트워크를 위한 Hadamard 행렬 인터스트 림 (interstream) 전송기반 blind 채널추정을 소개한다. 제안 방법은 다중 셀로 된 이동 단말 네트워크를 기반으로 연구 된다. MS (mobile station) 는 양 셀로부터 신호를 받는 것으로 가정한다. 가까운 셀로부터 받은 신호는 원하는 신호 로 간주되고, 다른 셀로부터 받은 신호는 간섭신호로 간주된다. 채널은 blind이기 때문에 채널을 추정하기 위해 Hadamard 행렬 패턴의 파일럿 (pilot) 스트림 (stream) 을 전송하면, 대규모 MIMO 채널에 대해 보다 쉽고 빠른 채널 추정이 가능하게 된다. Hadamard 행렬 기반시스템의 계산은 오직 복소 가산 (complex addition) 만 필요하기 때문에, 복소 승산 (complex multiplication) 이 필요한 Fourier 변환을 이용한 방법보다 복잡도가 훨씬 줄어든다. 수치적 분석 을 통해 본 결과 제안한 방법이 완벽함을 보여준다. In this paper, we introduce a Hadamard matrix interstream transmission based blind channel estimation for multi-cells multiple-input and multiple-output (MIMO) networks. The proposed scheme is based on a network with mobile stations (MS) which are deployed with multi cells. We assume that the MS have the signals from both cells. The signal from near cell are considered as desired signal and the signals from the other cells are interference signal. Since the channel is blind, so that we transmit Hadamard matrix pattern pilot stream to estimate the channel; that gives easier and fast channel estimation for large scale MIMO channel. The computation of Hadamard based system takes only complex additions, and thus the complexity of which is much lower than the scheme with Fourier transform since complex multiplications are not needed. The numerical analysis will give perfection of proposed channel estimation.

계산 복잡성이 단순화된 비선형 추정기를 사용한 Bussgang 블라인드 등화

오길남,Oh, Kil-Nam 대한전자공학회 2005 電子工學會論文誌-SP (Signal processing) Vol.42 No.6

이 논문에서는 계산 복잡성이 단순화된 비선형 추정기를 소개하고, 이를 적용한 Bussgang 블라인드 등화 알고리즘을 제안한다. 제안한 알고리즘은 베이즈 추정기가 눈 모형이 닫힌 등화 초기에는 시그모이드 추정기로 잘 근사화되며, 눈 모형이 열린 조건에서는 임계 추정기에 근사화되는 사실을 이용하였다. 제안 방법에서는 매 갱신 마다 채널 왜곡의 정도에 따라 시그모이드 추정기와 임계 추정기를 선택적으로 적용하고, 특히 시그모이드 추정기에 축소 신호점을 도입함으로써 고차 QAM 신호의 블라인드 등화에 적용 시 계산 복잡성을 극히 단순화하는 동시에 블라인드 수렴 특성과 정상상태 성능을 개선할 수 있음을 보인다. This paper introduces nonlinear estimators with reduced complexity, and proposes the Bussgang blind equalization algorithm employing the nonlinear estimators. The proposed algorithm utilized the facts that the Bayesian estimator is well approximated to the sigmoid estimator in initial stage of equalization with closed eye and is well approximated to the threshold estimator under open eye condition. The proposed method adopts selectively one of the two nonlinear estimators, i.e., the sigmoid estimator and the threshold estimator, according to channel distortion level at each iteration. As a result, by using the sigmoid estimator with reduced constellation, the proposed scheme, as it is applied to blind equalization of high-order QAM signals, simplifies the computational complexity extremely, and enhances the blind convergence capability and steady-state performance.

Blind Channel Estimation based on Hadamard Matrix Interstream Transmission for Multi-Cell MIMO Networks

양재승,모하마드 아부 하니프,박주용,이문호 한국인터넷방송통신학회 2015 한국인터넷방송통신학회 논문지 Vol.15 No.4

In this paper, we introduce a Hadamard matrix interstream transmission based blind channel estimationfor multi-cells multiple-input and multiple-output (MIMO) networks. The proposed scheme is based on anetwork with mobile stations (MS) which are deployed with multi cells. We assume that the MS have thesignals from both cells. The signal from near cell are considered as desired signal and the signals from theother cells are interference signal. Since the channel is blind, so that we transmit Hadamard matrix pattern pilotstream to estimate the channel; that gives easier and fast channel estimation for large scale MIMO channel. Thecomputation of Hadamard based system takes only complex additions, and thus the complexity of which ismuch lower than the scheme with Fourier transform since complex multiplications are not needed. Thenumerical analysis will give perfection of proposed channel estimation.

복층유리와 실내 블라인드 시스템의 집중 시뮬레이션 모델

윤경수(Yoon Kyung-Soo),김덕우(Kim Deuk-Woo),이건호(Lee Keon-Ho),박철수(Park Cheol-Soo) 대한건축학회 2009 대한건축학회논문집 Vol.25 No.12

The paper describes the calibration of a simulation model of a glazed curtain wall system with interior blinds. Rather than attempting to develop the most detailed and accurate model of the system, the approach described in this paper is based on the postulated 'minimalistic' model augmented with a parameter estimation technique. Then, the lumped simulation model was validated with measurements obtained from an in-situ full-scale experimental facility mounted on the south facing facade. It was found that the calibration method delivers accurate results for the “unknown” model parameters (convective heat transfer coefficients and air permeability of shading device), allowing the calibrated lumped model to be used in ensuing optimal control and performance studies.

움직임벡터의 변경 최소화 기법을 이용한 블라인드 비디오 워터마킹 기반의 문자 정보 은닉 기법

강경원,유태경,정태일,박태희,김종남,문광석,Kang, Kyung-Won,Ryu, Tae-Kyung,Jeong, Tae-Il,Park, Tae-Hee,Kim, Jong-Nam,Moon, Kwang-Seok 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.1C

최근 디지털 방송의 발달과 인터넷 보급으로 인해 디지털 데이터의 저작권 보호를 위한 디지털 워터마킹에 관한 많은 연구가 이루어지고 있다. 본 논문에서는 저작권 보호 뿐만 아니라 자막이나 인물 소개, 배경 음악에 대한 정보 등 유용한 정보를 은닉하면서 화질 열화를 최소화하기 위하여 움직임벡터의 변경 최소화 기법을 제안한다. 제안한 방법은 매크로블록에서 구한 정보와 워터마크 정보를 비교하여 특성 벡터를 추출하고, 이에 따라 비트의 반전 여부를 결정함으로써 움직임 벡터의 변경을 최소화한다. 따라서 기존의 움직임벡터 기반의 비디오 워터마킹기법에 비해 화질 열화가 최소화될 수 있다. 또한 삽입 정보에 대한 무결성을 제공하며, 워터마크를 매우 간단히 검출할 수 있고, 원 영상이 필요없는 블라인드 워터마킹이 가능하다. 그리고 기존의 비디오 스트림의 형식이 변경되지 않으므로 기존의 MPEG-1, -2 표준과 호환성이 뛰어나다. 본 논문은 실험 결과 기존의 방법에 비해 $0.5{\sim}1.5dB$ 화질이 향상됨을 확인할 수 있었다. With the advancement of the digital broadcasting and popularity of the Internet, recently, many studies are making on the digital watermarking for the copyright protection of digital data. This paper proposes the minimum modification method of motion vector to minimize the degradation of video quality, hiding subtitles of many language and information of OST(original sound track), character profiles, etc. as well as the copyright protection. Our proposed algorithm extracts feature vector by comparing motion vector data with watermark data, and minimize the modification of motion vectors by deciding the inversion of bit. Thus the degradation of video quality is minimized comparing to conventional algorithms. This algorithm also can check data integrity, and retrieve embedded hidden data simply and blindly. And our proposed scheme can be useful for conventional MPEG-1, -2 standards without any increment of bit rate in the compressed video domain. The experimental result shows that the proposed scheme obtains better video quality than other previous algorithms by about $0.5{\sim}1.5dB$.

Forgery Detection Using Noise Estimation and HOG Feature Extraction

Mandeep Kaur,Savita Walia 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.4

Forgery detection techniques are required to verify the authenticity of the digital images. The additional noise is the most general way to hide the traces of the tampering done to the image. Original images which do not undergo any alterations are supposed to have a consistency in noise variation. If the image is forged, the noise no longer remains consistent throughout the image. In this paper, a method is proposed to detect the forgery based upon noise estimation and hog feature extraction. The image is first converted to YIQ colorspace, and then the block segmentation is performed on Y component of the YIQ image. Noise is estimated using PCA and hog features are extracted from each block of the image. An unsupervised clustering method is used to cluster the blocks of the image. The experimental results show that the proposed technique detects forged images more effectively as compared to previous method based only on noise estimation.

분산 다중 전자전 센서를 이용한 ESPRIT 기반 비등간격 선형배열 MIMO 레이다의 암맹 직교신호 분리 기법

여광구(Kwanggoo Yeo),정원주(Wonzoo Chung) 한국전자파학회 2018 한국전자파학회논문지 Vol.29 No.11

본 논문에서는 안테나 배열 간격이 등간격 선형배열(uniform linear array)이 아닌 비등간격 선형배열인 MIMO(Multiple-Input Multiple-Output) 레이다의 직교신호 분리에 대하여 논의한다. 다중의 전파탐지기를 이용하여 얻은 신호를 기반으로 전파탐지기 배치를 통하여 새로운 rotational invariance 구조를 부여하여 ESPRIT 알고리즘을 이용할 수 있게 한다. 이를 통하여 수신신호로부터 직접 MIMO 레이다의 직교신호를 간단한 연산으로 암맹적으로 분리하는 방법을 제시한다. 추정된 직교신호를 이용하여 차후 MIMO 레이다의 무력화 혹은 기만에 활용할 수 있도록 한다. In this paper, we propose a blind estimation scheme for the antenna spacing of nonuniform linear array MIMO radar using distributed electronic sensors based on ESPRIT. We present a blind method to separate orthogonal waveforms of a MIMO radar based on the antenna spacing estimation. The estimated orthogonal waveforms of a MIMO radar can be used for disabling opponent MIMO radars.

Joint Blind Parameter Estimation of Non-cooperative High-Order Modulated PCMA Signals

( Yiming Guo ),( Hua Peng ),( Jun Fu ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.10

A joint blind parameter estimation algorithm based on minimum channel stability function aimed at the non-cooperative high-order modulated paired carrier multiple access (PCMA) signals is proposed. The method, which uses hierarchical search to estimate time delay, amplitude and frequency offset and the estimation of phase offset, including finite ambiguity, is presented simultaneously based on the derivation of the channel stability function. In this work, the structure of hierarchical iterative processing is used to enhance the performance of the algorithm, and the improved algorithm is used to reduce complexity. Compared with existing data-aided algorithms, this algorithm does not require a priori information. Therefore, it has significant advantage in solving the problem of blind parameter estimation of non-cooperative high-order modulated PCMA signals. Simulation results show the performance of the proposed algorithm is similar to the modified Cramer-Rao bound (MCRB) when the signal-to-noise ratio is larger than 16 dB. The simulation results also verify the practicality of the proposed algorithm.

A New Precoder Design for Blind Channel Estimation in MIMO-OFDM Systems

Song Noh,Youngchul Sung,Zoltowski, Michael D. IEEE 2014 IEEE Transactions on Wireless Communications Vol.13 No.12

<P>A new precoder for precoding-based blind channel estimation for MIMO-OFDM systems is proposed. In the proposed scheme, only a small number of data symbols, commensurate with the channel length, are linearly precoded prior to transmission to induce the signal correlation needed for the scheme to blindly estimate the channels. Similar to how pilot symbols are transmitted, the subcarriers carrying these linearly precoded data symbols are equi-spaced across the frequency band. The other subcarriers carry data symbols in the standard way, enabling MLD per subcarrier and also allowing for MIMO linear precoding across antennas at each subcarrier. This is in contrast to previous precoding-based blind channel estimation schemes which precode all of the data symbols so that every subcarrier carries a linear combination of symbols, aking the resulting joint MLD problem infeasible. In addition, this also makes it infeasible to employ MIMO precoding per subcarrier across the transmit antennas. The proposed precoder is designed via a multi-stage optimization process that seeks to minimize both channel estimation error and symbol estimation error. For channel estimation purposes, the resulting optimal design offers low-cost features such as sign change and FFT while providing reasonable channel estimation performance for low mobility applications.</P>

주파수 대역별 잔향시간 추정을 위한 변형된 AWSSDR 방식

김민식,김형순 한국음성학회 2023 말소리와 음성과학 Vol.15 No.4

Reverberation time (T60) is a typical acoustic parameter that provides information about reverberation. Since the impacts of reverberation vary depending on the frequency bands even in the same space, frequency-dependent (FD) T60, which offers detailed insights into the acoustic environments, can be useful. However, most conventional blind T60 estimation methods, which estimate the T60 from speech signals, focus on fullband T60 estimation, and a few blind FDT60 estimation methods commonly show poor performance in the low-frequency bands. This paper introduces a modified approach based on Attentive pooling based Weighted Sum of Spectral Decay Rates (AWSSDR), previously proposed for blind T60 estimation, by extending its target from fullband T60 to FDT60. The experimental results show that the proposed method outperforms conventional blind FDT60 estimation methods on the acoustic characterization of environments (ACE) challenge evaluation dataset. Notably, it consistently exhibits excellent estimation performance in all frequency bands. This demonstrates that the mechanism of the AWSSDR method is valuable for blind FDT60 estimation because it reflects the FD variations in the impact of reverberation, aggregating information about FDT60 from the speech signal by processing the spectral decay rates associated with the physical properties of reverberation in each frequency band.