we present an amicable-orthogonal-design-based differential space-time block code (ADSTBC) for multiple antennas.Compared with the existing differential space-time modulation designs
our scheme imposes no restrictions on underlying signal constellation
and therefore can improve the spectral efficiency by exploiting efficient modulation techniques such as QAM
APSK etc.We then derive a maximum-likelihood differential decoder (MLDD) with linear complexity for flat Rayleigh fading channels.Particularly
when the QAM constellation is used in ADSTBC
MLDD can be further simplified to independently detect the real and imaginary parts of each data symbol
and accordingly the implementation cost can be greatly reduced;Moreover
the computational amount for detecting single data symbol is kept constant in MLDD while the order of the QAM constellation increases.