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Adaptive Hard Decision Aided Fast Decoding Method in Distributed Video Coding (적응적 경판정 출력을 이용한 고속 분산 비디오 복호화 기술)

  • Oh, Ryang-Geun;Shim, Hiuk-Jae;Jeon, Byeung-Woo
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.47 no.6
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    • pp.66-74
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    • 2010
  • Recently distributed video coding (DVC) is spotlighted for the environment which has restriction in computing resource at encoder. Wyner-Ziv (WZ) coding is a representative scheme of DVC. The WZ encoder independently encodes key frame and WZ frame respectively by conventional intra coding and channel code. WZ decoder generates side information from reconstructed two key frames (t-1, t+1) based on temporal correlation. The side information is regarded as a noisy version of original WZ frame. Virtual channel noise can be removed by channel decoding process. So the performance of WZ coding greatly depends on the performance of channel code. Among existing channel codes, Turbo code and LDPC code have the most powerful error correction capability. These channel codes use stochastically iterative decoding process. However the iterative decoding process is quite time-consuming, so complexity of WZ decoder is considerably increased. Analysis of the complexity of LPDCA with real video data shows that the portion of complexity of LDPCA decoding is higher than 60% in total WZ decoding complexity. Using the HDA (Hard Decision Aided) method proposed in channel code area, channel decoding complexity can be much reduced. But considerable RD performance loss is possible according to different thresholds and its proper value is different for each sequence. In this paper, we propose an adaptive HDA method which sets up a proper threshold according to sequence. The proposed method shows about 62% and 32% of time saving, respectively in LDPCA and WZ decoding process, while RD performance is not that decreased.

Multi-code Biorthogonal Code Keying with Constant Amplitude Coding Combined with $Q^{2}PSK$ to Increase Bandwidth Efficiency (정 진폭 부호화된 Multi-code Biorthogonal Code Keying시스템에서 대역폭 효율 개선을 위해 $Q^{2}PSK$를 이용하는 방안)

  • Kim Sung-Pil;Kim Myoung-Jin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.5A
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    • pp.484-492
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    • 2006
  • A multi-code biorthogonal code keying(MBCK) system consists of multiple waveform coding block, and the sum of output codewords is transmitted. Drawback of MBCK is that it requires amplifier with high linearity because its output symbol is multi-level. MBCK with constant amplitude preceding blcok(CA-MBCK) has been proposed, which guarantees sum of orthogonal codes to have constant amplitude. Redundant bits of CA-MBCK for constant amplitude coding are not only used to make constant amplitude signal but also used to improve the bit error rate(BER) performance at receiver. In this paper, we proposed a transmission scheme which combine CA-MBCK with $Q^{2}PSK$ to improve bandwidth efficiency of CA-MBCK. The BER performance of the scheme is same that of CA-MBCK in additive white gaussian noise(AWGN). And we showed that BER performance of the proposed system can be improved using redundant bits of constant amplitude preceding.

A Design of Multi-Standard LDPC Decoder for WiMAX/WLAN (WiMAX/WLAN용 다중표준 LDPC 복호기 설계)

  • Seo, Jin-Ho;Park, Hae-Won;Shin, Kyung-Wook
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.17 no.2
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    • pp.363-371
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    • 2013
  • This paper describes a multi-standard LDPC decoder which supports 19 block lengths(576~2304) and 6 code rates(1/2, 2/3A, 2/3B, 3/4A, 3/4B, 5/6) of IEEE 802.16e mobile WiMAX standard and 3 block lengths(648, 1296, 1944) and 4 code rates(1/2, 2/3, 3/4, 5/6) of IEEE 802.11n WLAN standard. To minimize hardware complexity, it adopts a block-serial (partially parallel) architecture based on the layered decoding scheme. A DFU(decoding function unit) based on sign-magnitude arithmetic is used for hardware reduction. The designed LDPC decoder is verified by FPGA implementation, and synthesized with a 0.13-${\mu}m$ CMOS cell library. It has 312,000 gates and 70,000 bits RAM. The estimated throughput is about 79~210 Mbps at 100 MHz@1.8v.

Development of DSSS Uplink System for Missile Remote Control (유도탄 원격통제를 위한 대역확산 상향링크 시스템 개발)

  • Lee, Sangbum;Choi, Seoungduck;Kim, Whanwoo
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.8
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    • pp.110-118
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    • 2013
  • This paper describes the development of DSSS wireless communication uplink system for missile remote control. In consideration of low probability of intercept, low probability of exploitation, anti-jam, low latency, and doppler frequency offset, we used DSSS partially DBPSK. Also we used the selective diversity with two receiving antennas to mitigate multipath interference which is the dominant channel impairment and the turbo product code(TPC) for forward error correction(FEC) to improve bit error rate performance.

Application of Block Turbo Code for Improving the Performance of 5 ㎓ IEEE 802,11a WLAN System (5 ㎓대 IEEE 802.11a WLAN 시스템의 성능향상을 위한 블록터보코드(Block Turbo Code)의 응용)

  • 김한종;이병남
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.1
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    • pp.21-28
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    • 2004
  • In this paper we apply block turbo coding at the transmitter and iterative decoding algorithm at the receiver for different operating modes, based on the 5 ㎓ IEEE 802.1 la WLAN system, instead of convolutional coding and soft decision viterbi algorithm to improve forward error correcting performance. Experimental results showed that each coding scheme outperforms coding gains of up to 3.5 ㏈ at the BER of 10$\^$-3/.

A Design of Sign-magnitude based Multi-mode LDPC Decoder for WiMAX (Sign-magnitude 수체계 기반의 WiMAX용 다중모드 LDPC 복호기 설계)

  • Seo, Jin-Ho;Park, Hae-Won;Shin, Kyung-Wook
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.15 no.11
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    • pp.2465-2473
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    • 2011
  • This paper describes a circuit-level optimization of DFU(decoding function unit) for LDPC decoder which is used in wireless communication systems including WiMAX and WLAN. A new design of DFU based on sign-magnitude arithmetic instead of two's complement arithmetic is proposed, resulting in 18% reduction of gate count for 96 DFUs array used in mobile WiMAX LDPC decoder. A multi-mode LDPC decoder for mobile WiMAX standard is designed using the proposed DFU. The LDPC decoder synthesized using a 0.18-${\mu}m$ CMOS cell library with 50 MHz clock has 268,870 gates and 71,424 bits RAM, and it is verified by FPGA implementation.

Wyner-Ziv Video Compression using Noise Model Selection (잡음 모델 선택을 이용한 Wyner-Ziv 비디오 압축)

  • Park, Chun-Ho;Shim, Hiuk-Jae;Jeon, Byeung-Woo
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.46 no.4
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    • pp.58-66
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    • 2009
  • Recently the emerging demands of the light-video encoder promotes lots of research efforts on DVC (Distributed Video Coding). As an appropriate video compression method, DVC has been studied, and Wyner-Ziv (WZ) video compression is its one representative structure. The WZ encoder splits the image into two kinds of frames, one is key frame which is compressed by conventional intra coding, and the other is WZ frame which is encoded by WZ coding. The WZ decoder decodes the key frame first, and estimates the WZ frame using temporal correlation between key frames. Estimated WZ frame (Side Information) cannot be the same as the original WZ frame due to the absence of the WZ frame information at decoder. As a result, the difference between the estimated and original WZ frames are regarded as virtual channel noise. The WZ frame is reconstructed by removing noise in side information. Therefore precise noise estimation produces good performance gain in WZ video compression by improving error correcting capability by channel code. But noise cannot be estimated precisely at WZ decoder unless there is good WZ frame information, and generally it is estimated from the difference of corresponding key frames. Also the estimated noise is limited by comparing with frame level noise to reduce the uncertainty of the estimation method. However these methods cannot provide good noise estimation for every frame or each bit plane. In this paper, we propose a noise nodel selection method which chooses a better noise model for each bit plane after generating candidate noise models. Experimental result shows PSNR gain up to 0.8 dB.

A study for chirp signal method & system implementation in the PLC modem with low speed (저속 PLC 모뎀에서의 Chirp 신호 방식과 시스템 구현에 관한 연구)

  • Jeong, Young-Hwa;Sang-Gun Lee
    • The Journal of Information Technology
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    • v.7 no.3
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    • pp.37-45
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    • 2004
  • The representative communication method which is applied in the low-speed power line communication modem with 60bps is single carrier method. It has been used mainly for the control. The single carrier method is very sensitive to a power line communication channel environment. Specially, the severe attenuation of the transmission signal according to the notch characteristics of channel becomes the main cause of communication error. Domestic power line channel environment has this notable feature. In this paper, we implemented the low-speed power line communication system which used the chirp signal method to be strong in notch and noise characteristics. In this research, we proposed the method which transmits 1- '1 Unit symbol Chirp signal' with a 100${\mu}s$ time within 1ms for 1 bit. Also it applied for the Convolution code for an error correction and the Manchester code for a collision perception and an error detection. It used the method which uses the bit correlator for signal detection in the receiver parts. We confirmed that the communication method of the chirp method has a excellent performance compared to single carrier methods with a result of experiment of the low-speed power line communication system with the 60bps.

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Transmission Error Detection and Copyright Protection for MPEG-2 Video Based on Channel Coded Watermark (채널 부호화된 워터마크 신호에 기반한 MPEG-2 비디오의 전송 오류 검출과 저작권 보호)

  • Bae, Chang-Seok;Yuk, Ying-Chung
    • The KIPS Transactions:PartB
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    • v.12B no.7
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    • pp.745-754
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    • 2005
  • This paper proposes an information hiding algorithm using channel coding technique which can be used to detect transmission errors and to protect copyright for MPEG-2 video The watermark signal is generated by applying copyright information of video data to a convolutional encoder, and the signal is embedded into macro blocks in every frame while encoding to MPEG-2 video stream In the decoder, the embedded signal is detected from macro blocks in every frame, and the detected signal is used to localize transmission errors in the video stream. The detected signal can also be used to claim ownership of the video data by decoding it to the copyright Information. In this stage, errors in the detected watermark signal can be corrected by channel decoder. The 3 video sequences which consist of 300 frames each are applied to the proposed MPEG-2 codec. Experimental results show that the proposed method can detect transmission errors in the video stream while decoding and it can also reconstruct copyright information more correctly than the conventional method.

On algorithm for finding primitive polynomials over GF(q) (GF(q)상의 원시다항식 생성에 관한 연구)

  • 최희봉;원동호
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.11 no.1
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    • pp.35-42
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    • 2001
  • The primitive polynomial on GF(q) is used in the area of the scrambler, the error correcting code and decode, the random generator and the cipher, etc. The algorithm that generates efficiently the primitive polynomial on GF(q) was proposed by A.D. Porto. The algorithm is a method that generates the sequence of the primitive polynomial by repeating to find another primitive polynomial with a known primitive polynomial. In this paper, we propose the algorithm that is improved in the A.D. Porto algorithm. The running rime of the A.D. Porto a1gorithm is O($\textrm{km}^2$), the running time of the improved algorithm is 0(m(m+k)). Here, k is gcd(k, $q^m$-1). When we find the primitive polynomial with m odor, it is efficient that we use the improved algorithm in the condition k, m>>1.

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