差動形PSK変調方式における軟判定復号法

抄録

There are two decision methods to calculate metrics in bit-error correcting algorithms. One is a hard decision which uses bit values themselves. The other is a soft decision which uses a bit likelihood. The soft decision is superior to the hard decision in the coding gain.
However, in cases of differential phase shift keying (DPSK), there are some difficulties to calculate the bit likelihood, because it is affected by two continuous phases. This paper proposes new calculation algorithm for the bit likelihood in the DPSK.
The coding gain of the soft decision Viterbi decoding which utilizes the proposed algorithm is measured in comparison with the hard decision Viterbi decoding and with no convolutional coding on a static channel when an equalizer is not employed.
It is verified that the soft decision decoding method works effectively for the bit-error correction in the DPSK.