Multi-level differential decoding device and method for quadrature amplitude modulation communication system

摘要

Differential decoding processing applied to multilevel modulation is accomplished with the circuit scale kept small by including; an MSB coordinate rotating part for performing coordinate rotation based on information of the first two most significant bits of a signal received via a synchronous detection part; an MSB symbol likelihood generating part for generating likelihood with respect to the first two most significant bits after differential decoding, with the use of two sets of bit strings at different points in time for which coordinate rotation has been performed; an LSB symbol likelihood generating part for generating likelihood with respect to less significant bits; and a soft decision error correction decoding part for generating a decoded signal with the use of the likelihood of the first two most significant bits and the likelihood of the less significant bits.

主权项

1. A multilevel differential decoding device for a QAM modulation communication system which uses QAM modulation, comprising:
a synchronous detection part for receiving a signal in which differential encoding has been performed on first two most significant bits of an N-bit transmission symbol, where N≧4 holds; an MSB coordinate rotating part for performing coordinate rotation based on information of the first two most significant bits out of a reception symbol of the signal received via the synchronous detection part; an MSB symbol likelihood generating part for generating likelihood with respect to the first two most significant bits after differential decoding, with use of two sets of bit strings at different points in time for which coordinate rotation has been performed based on the first two most significant bits; an LSB symbol likelihood generating part for generating likelihood with respect to less significant bits out of the reception symbol of the received signal that are (N−2) bits on a least significant side; and a soft decision error correction decoding part for generating a decoded signal by performing error correction decoding processing with use of the likelihood of the first two most significant bits which has been generated by the MSB symbol likelihood generating part and the likelihood of the less significant bits which has been generated by the LSB symbol likelihood generating part.