An adaptive transmission power allocation (TPA) algorithm is presented for the turbobell labs layerecl spacetime(TurboBLAST) system. This algorithm aims to find the proper power allocation parameters with which the overall bit error rate (BER) can be minimized. At the transmitter, the TPA algorithm is used to allocate proper power to every antenna under the restriction of total transmission power. At the receiver, a modified iterative soft interference cancellation scheme is used to detect received signals to reduce BER further. Simulation results show that the BER of the proposed scheme can be decreased significantly compared with that of equal power allocation.