By introducing multiple levels quadrature amplitude modulation and matrix transform method

a multiple am-plitudes differential space-time coding（DSTC） scheme was developed.The scheme can avoid the performance loss of conventional DSTC schemes based on PSK modulation in high spectrum efficiency

and it can be applied to non-square code matrix.Compared with conventional PSK based single amplitude DSTC schemes

the developed scheme has higher spectrum efficiency by carrying information not only on phases but also on amplitudes.Moreover

it has linear decoding complexity

and higher code rate.Also

the performance of our DSTC scheme concatenated with channel codes was given.The simulations results show that our scheme has lower BER when compared with single amplitude DSTC schemes.And multiple amplitudes DSTC concatenated with channel coding also outperform corresponding single amplitude DSTC.