  An adaptive delay-tolerant distributed space-time coding (DSTC) scheme that
exploits feedback is proposed for two-hop cooperative MIMO networks. Maximum
likelihood (ML) receivers and adjustable code matrices are considered subject
to a power constraint with a decode-and-forward (DF) cooperation strategy. In
the proposed delay-tolerant DSTC scheme, an adjustable code matrix is employed
to transform the space-time coded matrix at the relay nodes. Least-squares (LS)
algorithms are developed with reduced computational complexity to adjust the
parameters of the codes. Simulation results show that the proposed algorithms
obtain significant performance gains and address the delay issue for
cooperative MIMO systems as compared to existing delay-tolerant DSTC schemes.
