A simple method that detects the data sequence and at the same time estimates the channel condition is proposed using the viterbialgorithm and fuzzy logic for the convolutional code. After a fixed number of decoding ...
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A simple method that detects the data sequence and at the same time estimates the channel condition is proposed using the viterbialgorithm and fuzzy logic for the convolutional code. After a fixed number of decoding steps, the fuzzy logic unit reads the branch metric value of the survivor and the difference between maximum and minimum survivor path metric values at the viterbi decoder and estimates the channel condition with the signal-to-noise ratio. The proposed method enables the channel estimation regardless of what kinds of modulator and demodulator are used. In the experiment, constraint length 7 and code rate 1/2 convolutional code that is standardized by the European Space Agency (ESA) is used. The effective movement range of the proposed channel estimation method is from 0.0 dB to 25 dB.
In the field of industrial automation research, wireless control in key application scenarios has become a research hotspot. Nevertheless, transmission over wireless channels in industrial environments is prone to int...
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ISBN:
(纸本)9781728129273
In the field of industrial automation research, wireless control in key application scenarios has become a research hotspot. Nevertheless, transmission over wireless channels in industrial environments is prone to interference, resulting in frequent erroneous packet deliveries. Forward Error Correction (FEC) code as an approach is able to effectively improve reliability and reduce the number of retransmissions. Therefore, channel coding needs further analysis to achieve better industrial wireless application. To this aim, this paper compares the decoding performance of convolutional codes and low-density parity-check ( LDPC) codes on the condition of short packet transmission. The metrics employed for evaluation are bit error rate (BER) and packet error rate (PER). The logarithmic belief propagation (Log-BP) algorithm and the viterbi decoding algorithm are adopted to LDPC codes and convolutional codes respectively. The results show that the decodingalgorithm of LDPC codes is prominent in short packet transmission.
We present a novel approach for reducing the computational complexity of updating homologies produced by a wide class of popular state-of-the-art algorithms in comparative computational biology. The algorithms that we...
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We present a novel approach for reducing the computational complexity of updating homologies produced by a wide class of popular state-of-the-art algorithms in comparative computational biology. The algorithms that we consider use hidden Markov models (HMMs) and a viterbi recursion to evaluate matches between sequences, or between a sequence and models. Such updates occur frequently in practice as researchers discover errors in biological sequences or analyze multiple nearly similar sequences, e.g., in a family of proteins that underwent mutations during evolution. The proposed algorithm interprets the viterbi recursion as an update of an optimal minimum spanning tree in a shortest path problem. We propose the novel concept of a relative node tolerance bound and show how it can be used to guarantee that one or more partial subtrees of a minimum spanning tree obtained before encountering the perturbations remain optimal. We also describe how to compute and use in real-time the relative node tolerance bounds to skip most unperturbed parts of a sequence while computing the new optimal solution. To further reduce the computational overhead associated with the tolerance bound evaluation, we present and exploit a statistical analysis of the matching procedure that estimates how many columns in the dynamic program that corresponds to the matching problem are affected by a change in a preceding column. The! resulting "reusable" viterbi decoding algorithm can update a matching result in less than a third to a fifth of the time required to compute a new match by performing a normal matching procedure, i.e., running a viterbialgorithm with updated sequences against a base hidden Markov model.
in this paper, an adaptive coding and modulation (ACM) technique is introduced in an attempt to maximize the channel throughout. This technique suggests five different pairs of coding and modulation techniques, starti...
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ISBN:
(纸本)9781538627358
in this paper, an adaptive coding and modulation (ACM) technique is introduced in an attempt to maximize the channel throughout. This technique suggests five different pairs of coding and modulation techniques, starting from low modulation orders and code rates going through higher values. Simulation over additive white Gaussian noise (AWGN) of the physical layer of the system is performed using M-phase shift keying (M-PSK) modulation and convolutional codes with soft viterbi decoding algorithm. In addition, the channel throughput for each Modulation and coding pair is obtained using specific packet retransmission mechanism. An algorithm for adaptive coding and modulation is developed and the overall throughout of the adaptive system is determined with respect to the received E-b/N-o values.
The Forward Error Correction (FEC) is appropriate technique used for controlling error in modern data transmission over noisy communication channels. Convolutional coding using viterbidecoding is one of the FEC techn...
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ISBN:
(纸本)9781509032433
The Forward Error Correction (FEC) is appropriate technique used for controlling error in modern data transmission over noisy communication channels. Convolutional coding using viterbidecoding is one of the FEC technique used in modern wireless communication system. This paper analysis the bit error rate (BER) performance of Convolutional code over different Code rates and Constraint length using hard-decision viterbi decoder. In this paper different Code rates 1/4, 1/3, 1/2, 2/3 and Constraint length from 3 to 8 are have been simulated using MATLAB over AWGN channel and QPSK modulation.
In this paper, soft-decision (SD) decoders of permutation trellis code (PTC) with M-ary frequency shift keying are designed using three optimization algorithms and presented in four decoding schemes. In a concatenated...
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In this paper, soft-decision (SD) decoders of permutation trellis code (PTC) with M-ary frequency shift keying are designed using three optimization algorithms and presented in four decoding schemes. In a concatenated code such as PTC, the viterbi decoder for the outer convolutional code provides maximum likelihood decoding. Hence, the error correction performance is dependent on the decoding scheme used for the inner code. Due to the structure of the encoder with the modulation scheme, the channel output can be interpreted as an assignment problem. SD decoding can then be designed accordingly, using the presented, low-complexity optimization-based schemes. The bit error rate (BER) performance of the schemes are simulated in an additive white Gaussian noise (AWGN) and powerline communication (PLC) channel. The complexities of the schemes are also presented. The performance of the SD schemes are compared with the existing SD threshold detector, with BER results showing significant coding gain for certain codebooks. From the results, a reasonable trade-off between the complexity and coding gain is observed for a noisy channel such as the PLC channel. (C) 2020 Elsevier B.V. All rights reserved.
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