Unitary space-time trellis codes

In this paper, a new noncoherent space-time coding scheme for the quasistatic flat fading channel is proposed. The proposed codes, called unitary space-time trellis codes, can be decoded by using the Viterbi algorithm without the knowledge of fading coefficients. The Viterbi decoder uses a sliding window for the observations where each observation covers several branches of the trellis. Appropriate decoding metrics for the observations are proposed also. We propose a systematic method for searching good unitary space-time trellis codes by computers. Simulation results indicate that the unitary space-time trellis codes are suitable for both the quasistatic and slow continuous flat fading channels.