The diversity techniques—space time block code (STBC), maximum ratio combining (MRC)—with multiple antennas provide better reliability than general system. But there are some limitations such as size, cost, hardware complexity, etc, because of multiple antennas. In this letter, we propose a cooperative transmission technique using STBC. We can overcome those limitations and give the gain of cooperative transmission diversity in a concept of virtual multi-input multi-output (MIMO) with single transmit antenna.