A new differential space-time block coding scheme

Most existing space-time coding schemes rely heavily on accurate channel estimation at the receiver., which is a difficult task in rapidly fading environment. The previous Tarokh and Jafarkhani (see IEEE Journal on Selected Areas in Comm., vol.18, no.7, p.1169-1174, 2000) differential space-time block code (DSTBC) suffers from the signal constellation expansion for QPSK and 8PSK modulation. We present a new differential space-time block coding scheme without constellation expansion. This is achieved by choosing differential coefficients appropriately in the signal mapping. The new scheme can be decoded by a Viterbi decoder. More importantly, it provides a differential coding gain of 1 dB-1.5 dB due to the redundancy introduced in the differential coding and it is only 2 dB away from the coherent space-time block codes.