• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.6
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• pp.1056-1063
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• 2008

This paper describes an efficient design of a multi-standard Viterbi decoder that supports multiple constraint lengths and code rates. The Viterbi decoder is parameterized for the code rates 1/2, 1/3 and constraint lengths 7,9, thus it has four operation nodes. In order to achieve low hardware complexity and low power, an efficient architecture based on hardware sharing techniques is devised. Also, the optimization of ACCS (Accumulate-Subtract) circuit for the one-point trace-back algorithm reduces its area by about 35% compared to the full parallel ACCS circuit. The parameterized Viterbi decoder core has 79,818 gates and 25,600 bits memory, and the estimated throughput is about 105 Mbps at 70 MHz clock frequency. Also, the simulation results for BER (Bit Error Rate) performance show that the Viterbi decoder has BER of $10^{-4}$ at $E_b/N_o$ of 3.6 dB when it operates with code rate 1/3 and constraints 7.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.568-573
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• 2002

In this paper, the Viterbi decoder containing new branch metrics of the squared Euclidean distance with multiple order phase differences is introduced in order to improve the bit error rate (BER) in the differential detection of the trellis-coded MDPSK-OFDM. The proposed Viterbi decoder is conceptually same as the Continuous multiple phase differential detection method that uses the branch metric with multiple phase differences. Also, we describe the Viterbi algorithm in order to use this branch metrics. Our study shows that such a Viterbi decoder improves BER performance without sacrificing bandwidth and power efficiency Also. the proposed algorithm ran be used in the single carrier modulation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.93-96
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• 2008

This paper describes an efficient design of a multi-standard Viterbi decoder that supports multiple constraint lengths and code rates. The Viterbi decode. is parameterized for the code rates 1/2, 1/3 and constraint lengths 7, 9, thus it has four operation modes. In order to achieve low hardware complexity and low power, an efficient architecture based on hardware sharing techniques is devised. Also, the optimization of ACCS (Accumulate-Subtract) circuit for the one-point trace-back algorithm reduces its area by about 35% compared to the full parallel ACCS circuit. The parameterized Viterbi decoder core has 79,818 gates and 25,600 bits memory, and the estimated throughput is about 105 Mbps at 70 MHz clock frequency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.8B
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• pp.1445-1452
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• 2000

In general, the communication channel can be modeled as inter-symbol interference(ISI) and additive white gaussian noise channel. Viterbi algorithm is optimum detector for transmitted data at transmitter, but it needs large computational complexity. For the sake of this problem, adaptive equalizers are employed for channel equalization which is not attractive for mixed phase channel. In this paper, we propose the effective new channel equalizer for mixed phase channel and show the better performance than previous equalizers.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.08a
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• pp.77-80
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• 2000

본 논문은 IEEE 802.11a에 의해 규정되어진 데이터 율 12Mbps, 부호화 율 1/2, 구속장이 7인 무선LAN용 비터비 디코더를 설계하고 구현한다. 구현에 앞서 각 구속장에 따른 전달함수를 구하여 각 구속장 별 first event 에러 확률과 비트 에러 확률을 구한다. 4bit연성판정을 위해 입력 심볼을 16단계로 양자화 하였으며 역 추적을 위한 방식으로 메모리를 사용하는 대신 새로운 알고리듬을 적용한 레지스터 교환방식을 사용함으로써 majority voting을 가능하도록 하였다 고속의 데이터를 처리하기 위해 병렬구조를 갖는 설계를 FPGA 칩을 사용하여 구현하였고 AWGN 환경 하에서 성능검증을 하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.3
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• pp.240-244
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• 2019

SOQPSK-TG which consists of differential precoder and CPM modulator was adopted as telemetry standard because of its high power and bandwidth efficiency. We proposed four-state Viterbi decoder for SOQPSK-TG. Reducing the trellis state to four was possible by simplifying frequency pulse of SOQPSK-TG to square pulse of symbol length 2 and combing this with differential precoder. Compared with conventional SOQPSK-TG receivers, computer simulation result shows about 1 dB performance improvement was achieved at BER of $10^{-5}$ in AWGN channel.

• The Journal of the Acoustical Society of Korea
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• v.30 no.3
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• pp.149-157
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• 2011

In this paper, we propose a new cardiac disorder classification method using an support vector machine (SVM) to combine hidden Markov model (HMM) and murmur existence information. Using cepstral features and the HMM Viterbi algorithm, we segment input heart sound signals into HMM states for each cardiac disorder model and compute log-likelihood (score) for every state in the model. To exploit the temporal position characteristics of murmur signals, we divide the input signals into two subbands and compute murmur probability of every subband of each frame, and obtain the murmur score for each state by using the state segmentation information obtained from the Viterbi algorithm. With an input vector containing the HMM state scores and the murmur scores for all cardiac disorder models, SVM finally decides the cardiac disorder category. In cardiac disorder classification experimental results, the proposed method shows the relatively improvement rate of 20.4 % compared to the HMM-based classifier with the conventional cepstral features.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.3A
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• pp.188-195
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• 2002

The M-algorithm for decoding convolutional codes can significantly reduce the complexity of the Viterbi algorithm by tracking a fixed number of survivor paths in each level of the decoding trellis. It is an easily-implementable algorithm suited for real-time processing of high-speed data. The algorithm, however, generates a sequence of catastrophic errors when the correct path is not included in the set of survivor paths. In this paper, the performance of the M-algorithm obtained from using various decoding complexity levels, frame lengths, and code constraint lengths is presented. The performance gain is quantified when the algorithm is used in conjunction with codes of increased constraint length. In particular, it is demonstrated the gain from the increased code free distance overcompensates the loss from the correct path being excluded from the survivors, when the frame length is short to moderate. Using 64 survivor paths, the signal-to-noise ratio gain obtained by increasing the constraint length from K=7 to K=9, 11, 15 is respectively 0.6, 0.75, and 08dB, when the frame of length L=100 has the frame error rate of 0.01%.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.4 no.3
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• pp.54-62
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• 1993

In this paper, performance comparisions of MTCM systems with 8DPSK over mobile communication channels are obtained by computer simulation. The multiple symbol differential detection scheme is introduced in order to improve the bit error rate performance in the detection of the trellis-coded 8DPSK system. Rician fading channels are used as test channels. The simula- tion results show that the trellis-coded 8DPSK system with multiple symbol detection gives better performance than that of the uncoded DQPSK system. And symbol by symbol interleaving method gives better performance than the symbol pair interleaving method.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.8
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• pp.100-110
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• 1994

This paper proposes an efficient traceback method for parallel hardware implementation of the Viterbi algorithm. Compared to the conventional Viterbi algorithm where initial state for traceback is selected arbitrarily the proposed algorithm decides decoding output by analyzing the survivor paths of consecutive tracebacks. This makes Viterbi algorithm more efficient in error correction event when more than one survivor path exists. The proposed traceback algorithm together with its hardware realization is presented in this paper. Experimental results show tht the proposed algorithms is efficient in error correction in noisy channels compared to the existing algorithms.