Two key problems in the asynchronous space-time cooperative transmission systems are the loss of OSTBC’s orthogonality and the channel dispersion

which may prevent the direct use of OSTBC and lead to severe performance degradation.To solve these problems

this paper proposes a new cooperative transmission scheme based on SC-FDE.Adopting the idea of OSTBC

simple operations such as reversal and conjugation are performed on the transmitting data at each relay node.The destination node performs FFT on the receiving data

then separates the superimposed frames by linear combination.The outputs of the combination are equalized by a frequency domain equalizer.At last IFFT is performed on the equalized data to recover the original data.By using FFT and IFFT

the new scheme has low complexity.Theoretic analysis and simulation results show that the new scheme can achieve diversity gain supplied by OSTBC even without perfect synchronization.