The transmitting end (TE) in system includes encoder, interlacing device (ID), parallel to serial converter (PSC), modulator, and time space convertor (TSC). The receiving end (RE) includes soft input/output detector, decoder, ID, de-ID, PSC, TSC, and reverse TSC. Being time-space mapped to different antennae, unitive encoded sequence at TE is transmitted out after independent encoding is carried out again. Unitive encoder (UE) and branch encoder (BE) are cascaded by using similar Turbo encoding mode. After being tested by the soft output, the signal received by RE is de-multiplexed into prior info of code word for each BE and prior info of check bit for UE. After soft decoding for each branch sequence, BE outputs additional info of info bit, which is as prior info of info bit for UE. Soft decoding is carried out for the said prior info to output final judgment. Features are: low error rate, flexible encoding. The invention is applicable to MIMO comm system in high speed.