• 대한전자공학회논문지SP
• /
• 제49권4호
• /
• pp.120-128
• /
• 2012

본 논문에서는 불균일한 클러터 환경에서 다중 표적탐지 성능을 향상시키기 위한 변형된 반복 백색화 투영 통계(modified iterative pre-whitening projection statistics: MIPPS) 기법을 제안하였다. MIPPS 기법은 항공기용 레이더에서 사용하는 시공간 적응 처리(space-time adaptive processing) 알고리듬의 불균일성 검출(non-homogeneity detection: NHD) 기법으로 반사신호 세기가 서로 다른 다수의 표적이 근접거리에 혼재되어 있는 환경에서 우수한 표적탐지 성능을 나타낸다. 모의실험을 통해 기존의 다양한 NHD 기법들의 성능을 분석하고, 본 논문에서 제안하는 MIPPS 기법이 강한 표적신호에 의해 야기되는 마스킹 효과(masking effect)를 최소화하면서 반사신호 세기가 약한 표적에 대한 평균 탐지 확률을 향상시킬 수 있음을 확인하였다.

• 한국통신학회논문지
• /
• 제38C권11호
• /
• pp.1051-1059
• /
• 2013

논문에서는 부호화된 MIMO 시스템에서 연판정 반복 검출 방식과 결합하여 효율적으로 사용될 수 있는 복잡도가 감소된 리스트 구 복호 (list sphere decoding; LSD) 방식을 제안한다. 기존의 LSD 방식은 고정된 값의 반지름을 이용하여 후보 신호들을 검색하였다. 그러나, 정해진 수 만큼의 후보 리스트들이 모두 채워지면, 이들에 대한 최대 또는 평균 반지름은 줄어들 가능성이 매우 크다. 반지름을 줄이게 되면 복잡도 또한 줄일 수 있게 된다. 본 논문에서는 LSD 기반의 MIMO 검출 시스템에서 효율적으로 사용될 수 있는 매우 간단한 반지름 갱신 방식 및 이를 이용한 연판정 반복 MIMO 검출 기법을 제안한다. 또한 터보 부호를 이용하여, 연판정 입출력을 이용하는 반복 MIMO 검출 방식에 대한 성능 평가 결과를 제시한다. 본 논문에서 제시된 시뮬레이션 결과에 따르면, 제안된 방식은 기존의 LSD 방식을 사용하는 것에 비해 거의 유사한 비트오류율 성능을 유지하면서도 복잡도를 크게 감소시킬 수 있다.

• Journal of Communications and Networks
• /
• 제12권5호
• /
• pp.475-479
• /
• 2010

The clipping value, defined as the log-likelihood ratio (LLR) in the case wherein all the list of candidates have the same binary value, is investigated, and an effective method to estimate it is presented for iterative tree search detection. The basic principle behind the method is that the clipping value of a channel bit is equal to the LLR of the maximum probability of correct decision of the bit to the corresponding probability of erroneous decision. In conjunction with multilevel bit mappings, the clipping value can be calculated with the parameters of the number of transmit antennas, $N_t$; number of bits per constellation point, $M_c$; and variance of the channel noise, $\sigma^2$, per real dimension in the Rayleigh fading channel. Analyses and simulations show that the bit error performance of the proposed method is better than that of the conventional fixed-value method.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제11권4호
• /
• pp.1954-1971
• /
• 2017

In this work, first, a multiuser detection (MUD) algorithm based on component-level soft interference cancellation and linear minimum mean square error (CLSIC-LMMSE) is proposed, which can enhance the bit error ratio (BER) performance of the traditional SIC-LMMSE-based MUD by mitigating error propagation. Second, for non-binary low density parity check (NB-LDPC) coded high-order modulation systems, when the proposed algorithm is integrated with partial mapping, the receiver with iterative detection and decoding (IDD) achieves not only better BER performance but also significantly computational complexity reduction over the traditional SIC-LMMSE-based IDD scheme. Extrinsic information transfer chart (EXIT) analysis and numerical simulations are both used to support the conclusions.

• Structural Monitoring and Maintenance
• /
• 제1권1호
• /
• pp.89-110
• /
• 2014

Structural Health Monitoring (SHM) is an effective alternative to conventional inspections which are time-consuming and subjective. SHM can detect damage early and reduce maintenance cost and thereby help reduce the likelihood of catastrophic structural events to infrastructure such as bridges. After reviewing the Damage Index Method (DIM), an Iterative Damage Index Method (IDIM) is proposed to improve the accuracy of damage detection. These two damage detection techniques are compared based on damage on two structures, a simply supported beam and a pedestrian bridge. Compared to the traditional damage detection algorithm, the proposed IDIM is shown to be less arbitrary and more accurate.

• 연구논문집
• /
• 통권25호
• /
• pp.147-154
• /
• 1995

In this paper, we discussed the convergence and the properties of an iterative algorithm method in order to improve a bimean clustering algorithm. This algorithm that we have discussed choose automatically an optimum threshold as a result of an iterative process, successive iterations providing increasingly cleaner extractions of the object region, The iterative approach of a proposed algorithm is seen to select an appropriate threshold for the low contrast images.

• ETRI Journal
• /
• 제39권3호
• /
• pp.326-335
• /
• 2017

In the uplink transmission of massive (or large-scale) multi-input multi-output (MIMO) systems, large dimensional signal detection and its hardware design are challenging issues owing to the high computational complexity. In this paper, we propose low-complexity hardware architectures of Richardson iterative method-based massive MIMO detectors. We present two types of massive MIMO detectors, directly mapped (type1) and reformulated (type2) Richardson iterative methods. In the proposed Richardson method (type2), the matrix-by-matrix multiplications are reformulated to matrix-vector multiplications, thus reducing the computational complexity from $O(U^2)$ to O(U). Both massive MIMO detectors are implemented using a 65 nm CMOS process and compared in terms of detection performance under different channel conditions (high-mobility and flat fading channels). The hardware implementation results confirm that the proposed type1 Richardson method-based detector demonstrates up to 50% power savings over the proposed type2 detector under a flat fading channel. The type2 detector indicates a 37% power savings compared to the type1 under a high-mobility channel.

• ETRI Journal
• /
• 제41권3호
• /
• pp.316-325
• /
• 2019

Accurate suppressive jamming is a prominent problem faced by radar equipment. It is difficult to solve signal detection problems for extremely low signal to noise ratios using traditional signal processing methods. In this study, a joint sensing dictionary based compressed sensing and adaptive iterative optimization algorithm is proposed to counter suppressive jamming in information domain. Prior information of the linear frequency modulation (LFM) and suppressive jamming signals are fully used by constructing a joint sensing dictionary. The jamming sensing dictionary is further adaptively optimized to perfectly match actual jamming signals. Finally, through the precise reconstruction of the jamming signal, high detection precision of the original LFM signal is realized. The construction of sensing dictionary adopts the Pei type fast fractional Fourier decomposition method, which serves as an efficient basis for the LFM signal. The proposed adaptive iterative optimization algorithm can solve grid mismatch problems brought on by undetermined signals and quickly achieve higher detection precision. The simulation results clearly show the effectiveness of the method.

• 제어로봇시스템학회논문지
• /
• 제17권1호
• /
• pp.22-30
• /
• 2011

Plane detection is very important information for mission-critical of robot in 3D environment. A representative method of plane detection is Hough-transformation. Hough-transformation is robust to noise and makes the accurate plane detection possible. But it demands excessive memory and takes too much processing time. Iterative randomized Hough-transformation has been proposed to overcome these shortcomings. This method doesn't vote all data. It votes only one value of the randomly selected data into the Hough parameter space. This value calculated the value of the parameter of the shape that we want to extract. In Hough parameters space, it is possible to detect accurate plane through detection of repetitive maximum value. A common problem in these methods is that it requires too much computational cost and large number of memory space to find the distribution of mixed multiple planes in parameter space. In this paper, we detect multiple planes only via data sampling using Self Organizing Map method. It does not use conventional methods that include transforming to Hough parameter space, voting and repetitive plane extraction. And it improves the reliability of plane detection through division area searching and planarity evaluation. The proposed method is more accurate and faster than the conventional methods which is demonstrated the experiments in various conditions.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제12권3호
• /
• pp.1016-1030
• /
• 2018

In this paper, an error-detection-coding-aided iterative hard decision interference cancellation (EDC-IHIC) scheme for multiple-input multiple-output systems employing hybrid automatic repeat request (HARQ) for multi-packet transmission is developed and investigated. In the EDC-IHIC scheme, only packets identified as error-free by the EDC are submitted to the interference cancellation (IC) stage for cancellation from the received signals. Therefore, the possibility of error propagation, including inter-transmission error propagation, can be eliminated using EDC-IHIC. Because EDC must be implemented in systems that employ HARQ to determine packet retransmission, error propagation can be prevented without the need for additional redundancy. The results of simulations conducted herein verify that the EDC-IHIC scheme outperforms conventional hard decision IC schemes in terms of the packet error rate in various environments.