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DECODER AND METHOD FOR DECODING INFORMATION GENERATED BY TAIL-BITING TRELLIS CODE HAVING M ENCODER STATES
DECODER AND METHOD FOR DECODING INFORMATION GENERATED BY TAIL-BITING TRELLIS CODE HAVING M ENCODER STATES
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机译:具有M编码器状态的比特尾车码产生的信息的解码器和方法
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摘要
A circular MAP decoder for error-correcting trellis codes that employ tail biting produces soft-decision outputs provides an estimate of the probabilities of the states in the first stage of the trellis, which probabilities replace the a priori knowledge of the starting state in a conventional MAP decoder. The circular MAP decoder provides the initial state probability distribution in either of two ways. The first involves a solution to an eigenvalue problem for which the resulting eigenvector is the desired initial state probability distribution; with knowledge of the starting state, the circular MAP decoder performs the rest of the decoding according to the MAP decoding algorithm. The second is based on a recursion for which the iterations converge to a starting state distribution. After sufficient iterations, a state on the circular sequence of states is known with high probability, and the circular MAP decoder performs the rest of the decoding according to the MAP decoding algorithm.
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