• Journal of Broadcast Engineering
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• v.17 no.1
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• pp.140-151
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• 2012

In Wyner-Ziv coding, key picture is encoded by conventional H.264/AVC intra coding which has low complexity. Although inter coding is more efficient than intra coding, its complexity is much higher than intra coding due to its motion estimation. Since the main feature of Wyner-Ziv coding is low complexity of encoder, inter coding is not suitable to encode key picture in Wyner-Ziv coding. However, inter picture coding with zero motion vector can be usable for Wyner-Ziv key picture coding instead of intra coding. Moreover, while current transform-domain Wyner-Ziv residual coding only utilizes temporal correlation of WZ picture, if zero motion coding is jointly used to encode key picture in transform-domain Wyner-Ziv residual coding, there will be a significant improvement in R-D performance. Experimental results show that the complexity of Wyner-Ziv coding with the proposed zero motion key picture coding is higher than conventional Wyner-Ziv coding with intra key picture coding by about 9%, however, there are BDBR gains up to 54%. Additionally, if the proposed zero motion key coding is implemented on top of the transform-domain Wyner-Ziv residual coding, the result shows rate gains up to 70% in BDBR compared to conventional Wyner-Ziv coding with intra key picture coding.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.4
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• pp.79-89
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• 2010

Recently, distributed video coding (DVC) has been actively studied for low complexity video encoder. The complexity of the encoder in DVC is much simpler than that of traditional video coding schemes such as H.264/AVC, but the complexity of the decoder in DVC increases. In this paper, we propose the Region-Of-Interest (ROI) based DVC with low decoding complexity. The proposed scheme uses the ROI, the region the motion of objects is quickly moving as the input of the Wyner-Ziv (WZ) encoder instead of the whole WZ frame. In this case, the complexity of encoder and decoder is reduced, and the bite rate decreases. Experimental results show that the proposed scheme obtain 0.95 dB as the maximum PSNR gain in Hall Monitor sequence and 1.87 dB in Salesman sequence. Moreover, the complexity of encoder and decoder in the proposed scheme is significantly reduced by 73.7% and 63.3% over the traditional DVC scheme, respectively. In addition, we employ the layered belief propagation (LBP) algorithm whose decoding convergence speed is 1.73 times faster than belief propagation algorithm as the Low-Density Parity-Check (LDPC) decoder for low decoding complexity.

• ETRI Journal
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• v.36 no.6
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• pp.894-904
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• 2014

Blind mismatch correction of time-interleaved analog-to-digital converters (TI-ADC) is a challenging task. We present a practical blind calibration technique for low-computation, low-complexity, and high-resolution applications. Its key features are: dramatically reduced computation; simple hardware; guaranteed parameter convergence with an arbitrary number of TI-ADC channels and most real-life input signals, with no bandwidth limitation; multiple Nyquist zone operation; and mixed-domain error correction. The proposed technique is experimentally verified by an M = 4 400 MSPS TI-ADC system. In a single-tone test, the proposed practical blind calibration technique suppressed mismatch spurs by 70 dB to 90 dB below the signal tone across the first two Nyquist zones (10 MHz to 390 MHz). A wideband signal test also confirms the proposed technique.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.9
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• pp.1171-1180
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• 1995

In this paper, we present a 3-D object recognition system in which the 3-D Hough transform domain is employed to represent the 3-D objects. In object modeling step, the features for recognition are extracted from the CAD models of objects to be recognized. Since the approach is based on the CAD models, the accuracy and flexibility are greatly improved. In matching stage, the sensed image is compared with the stored model, which is assumed to yield a distortion (location and orientation) in the 3-D Hough transform domain. The high dimensional (6-D) parameter space, which defines the distortion, is decomposed into the low dimensional space for an efficient recognition. At first we decompose the distortion parameter into the rotation parameter and the translation parameter, and the rotation parameter is further decomposed into the viewing direction and the rotational angle. Since we use the 3-D Hough transform domain of the input images directly, the sensitivity to the noise and the high computational complexity could be significantly alleviated. The results show that the proposed 3-D object recognition system provides a satisfactory performance on the real range images.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11C
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• pp.673-681
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• 2011

In this paper, we design multiple antenna relay transmission schemes of low complexity to enhance the spatial diversity in orthogonal frequency division multiplexing (OFDM) systems. The relay scheme underlined, can provide space time block coding (STBC) of OFDM signals in the time domain without IFFT and FFT operations with much reduced complexity. In this paper, we modify the conventional low-complexity STBC-OFDM relaying scheme to be compatible to the existing OFDM systems. In addition, we extend the proposed scheme for multiple antenna relays and provide performance enhancement strategies according to the channel quality information available at the relay. The proposed scheme is shown to improve the diversity and thereby to reduce the outage probability and coded bit error rate. Therefore, the proposed scheme will be promising for service quality improvement or coverage extension based on OFDM like wireless LANs and maritime communications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2C
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• pp.148-154
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• 2010

In this paper, we first review LDPC codes in general and a belief propagation algorithm that works in logarithm domain. LDPC codes, which is chosen 802.11n for wireless local access network(WLAN) standard are required a large number of computation due to large size of coded block and iteration. Therefore, we presented three kinds of low computational algorithm for LDPC codes. First, sequential decoding with partial group is proposed. It has same H/W complexity, and fewer number of iteration's are required at same performance in comparison with conventional decoder algorithm. Secondly, we have apply early stop algorithm. This method is reduced number of unnecessary iteration. Third, early detection method for reducing the computational complexity is proposed. Using a confidence criterion, some bit nodes and check node edges are detected early on during decoding. Through the simulation, we knew that the iteration number are reduced by half using subset algorithm and early stop algorithm is reduced more than one iteration and computational complexity of early detected method is about 30% offs in case of check node update, 94% offs in case of check node update compared to conventional scheme.

• Journal of Communications and Networks
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• v.15 no.5
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• pp.496-503
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• 2013

In an orthogonal frequency division multiplexing system, conventional interpolation techniques cannot correctly balance performance and overhead when estimating dynamic long-delay channels in single frequency networks (SFNs). In this study, classical filter analysis and design methods are employed to derive a complex interpolator for maximizing the resistible echo delay in a channel estimator on the basis of the correlation between frequency domain interpolating and time domain windowing. The coefficient computation of the complex interpolator requires a key parameter, i.e., channel length, which is obtained in the frequency domain with a tentative estimation scheme having low implementation complexity. The proposed complex adaptive interpolator is verified in a simulated digital video broadcasting for terrestrial/handheld receiver. The simulation results indicate that the designed channel estimator can not only handle SFN echoes with more than $200{\mu}s$ delay but also achieve a bit-error rate performance close to the optimum minimum mean square error method, which significantly outperforms conventional channel estimation methods, while preserving a low implementation cost in a short-delay channel.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.2C
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• pp.110-120
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• 2003

In this paper, we propose a Multiresolution Motion Estimation(MRME) adapted to Low-Band-Shift(LBS) method in wavelet domain. To overcome shift-variant property on wavelet coefficients, the LBS was previously proposed. This method which is applied to reference frame in video coding technique, has superior performance in terms of rate-distortion characteristic. However, this method needs more memory and computational complexity. In this paper, The computational complexity of the proposed method(LBS-MRME) is about 15.6% of that of existing method at 3-level wavelet transform. And although it has about 7 times as much as existing method's motion vector since each subband has different motion vector, it decreases motion compensated prediction error by detailed motion estimation, and then has better efficient coding performance. The experimental results with the proposed method showed about 0.3∼11.6% improvement of MAD performance in case of lossless coding, and 0.3∼3.0㏈ improvement of PSNR performance at the same bit rate in case of lossy coding.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.596-599
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• 2004

We propose an Alamouti-like scheme for combining space-time block coding with single-carrier frequency-domain equalization(SC-FDE) in fixed broadband wireless access environment. With two transmit antennas, the scheme is shown to achieve significant diversity gains at low complexity over frequency-selective fading channels

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.2
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• pp.86-88
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• 2002

An estimation method for the characteristic parameters in the low frequency signal is proposed in this paper. A low frequency signal is assumed to be modulated or distorted by high frequency terms. The algorithm proposed in this paper is designed to select set of local maximums in a successive manner, hence it is denoted as the iterative peak picking(IPP) algorithm. The IPP algorithm is operating in the time domain and is using only the comparison operation between two neighboring samples. Therefore, its computational complexity is very low and the delay caused by the computation is negligible, which make the real-time operation possible with economic hardware. The proposed algorithm is verified on the pitch estimation of speech signal and blood pulse estimation.