Apparatus and method for space- time coded multiple antenna system

A space-time coding apparatus in a MIMO(Multiple Input Multiple Output) system and a method thereof are provided to adjust space-time codes flexibly according to a channel environment by adjusting the number of bases, flexibly adjusting the diversity order and the multiplexing order, and executing space-time coding. A transmitter in a MIMO system comprises a space-time code controller(107) and a space-time coder(109). The space-time code controller(107) confirms the multiplexing order contained in the feedback information received from a receiving block. The space-time code controller(107) calculates the number of bases according to the confirmed multiplexing order and selects bases according to the calculated number. Using the selected bases, the space-time coder(109) configures a space-time code. Based on the configured space-time code, the space-time coder(109) executes space-time coding for transmission symbols.