## Abstract

Adaptive maximum likelihood differential detection implemented by a reduced state-transition Viterbi algorithm (called adaptive 3-state RSTVDD) is presented for adaptive reception of A/-ary differential phase shift keying (DPSK) signals transmitted over additive white Gaussian noise (AWGN) and frequency-nonselective Rayleigh fading channels. The adaptive 3-state RSTVDD comprises 1DD, a differential encoder, and reverse modulator, followed by reduced-state (3-state) Viterbi DD (RSVDD) with adaptive phase reference estimation. The adaptive 3-state RSVDD detector estimates the sequence of phase errors of the 1DD output. The phase reference estimator is an adaptive least mean square (LMS) filter with a step-size that adapts to changing channel conditions. The final detected symbol sequence is the modulo-27r sum of the 1DD output phase sequence and the detected phase error sequence. The bit error rate (BER) performance of A/-ary DPSK, A/=4, 8, and 16, in the AWGN and Rayleigh fading channels is evaluated by computer simulation to show that adaptive 3-state RSTVDD can achieve almost the same BER performance as the previously developed adaptive A/-state RSVDD. Since the number of trellis states is reduced to three irrespective of A/, the adaptive 3-state RSTVDD has lower computation complexity and it is particularly useful for A/-ary DPSK with M > 8.

Original language | English |
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Pages (from-to) | 156-163 |

Number of pages | 8 |

Journal | IEICE Transactions on Communications |

Volume | E82-B |

Issue number | 1 |

Publication status | Published - 1999 Jan 1 |

Externally published | Yes |

## Keywords

- Adaptive channel estimation
- Differential detection
- Fading
- M-ary dpsk
- Viterbi algorithm

## ASJC Scopus subject areas

- Software
- Computer Networks and Communications
- Electrical and Electronic Engineering