This thesis addresses the problem of the high computation complexity issue that arises when decoding hidden Markov models (HMMs) with a large number of states. A novel approach, the two-beam Viterbi, with an extra forward beam, for decoding HMMs is implemented on a system that uses factorial HMM to simultaneously recognize a pair of isolated digits on one audio channel. The two-beam Viterbi alg...

The Performance of the Viterbi algorithm with a new Polya contagion noise process is analyzed. The markov channel is the memory channel usually studied in the bibliography. The Polya channel was introduced years ago as a special case of a memory channel. In this work, the Polya contagion scheme is considered as a noise process and a GaussPolya noise model is introduced this way in order to perf...

Cyclic Redundancy Codes (CRC) code provides a simple, yet powerful, method for the detection of errors during digital data transmission and storage. Convolutional Coding and Decoding (CODEC) is a Forward Error Correction (FEC) technique that is particularly suited for a channel in which the transmitted signal is corrupted mainly by Additive White Gaussian Noise (AWGN). The Viterbi Algorithm (VA...

The growth of information available to learning systems and the increasing complexity of learning tasks determine the need for devising algorithms that scale well with respect to all learning parameters. In the context of supervised sequential learning, the Viterbi algorithm plays a fundamental role, by allowing the evaluation of the best (most probable) sequence of labels with a time complexit...

In wireless communication, the channel state changes repeatedly. In this situation, we select the specification of the Viterbi decoder for the worst case channel state. However, if we select the specification of the Viterbi decoder with such a criterion, the decoder operates inefficiently in the good channel state. In this paper, we propose a specification controllable Viterbi decoder without u...

In this paper an extended Viterbi algorithm is presented for first-order hidden Markov processes, with the help of a dummy combined state sequence. For this, the Markov switching’s transient probabilities and steady probabilities are studied separately. The algorithm gives a maximum likelihood estimate for the state sequence of a hidden Markov process. Comparing with the standard Viterbi algori...

The Viterbi algorithm is widely used in communications and signal processing. Recently, several area{ e cient architectures for this algorithm have been proposed. Area{e cient architectures trade speed for area by means of mapping the N states of the trellis describing the Viterbi algorithm to P processing elements, where N > P . In this paper a practical VLSI implementation of an area{e cient ...

Using coherent optical detection and digital signal processing, laser phase noise and equalization enhanced phase noise can be effectively mitigated using the feed-forward and feed-back carrier phase recovery approaches. In this paper, theoretical analyses of feed-back and feed-forward carrier phase recovery methods have been carried out in the long-haul high-speed n-level phase shift keying (n...

This paper presents an efficient and optimal parsing algorithm for probabilistic context-free grammars (PCFGs). To achieve faster parsing, our proposal employs a pruning technique to reduce unnecessary edges in the search space. The key is to repetitively conduct Viterbi inside and outside parsing, while gradually expanding the search space to efficiently compute heuristic bounds used for pruni...