Methods and apparatuses are provided for uplink MIMO transmissions in a wireless communication system. In particular, a primary stream (610) may be utilized to carry a primary data channel E-DPDCH (624), and a secondary stream (612) may be utilized to carry a secondary data channel S-E-DPDCH (620). Further, the primary stream (610) may be precoded utilizing a primary precoding vector, and the secondary stream (612) may be precoded utilizing a secondary precoding vector, with coefficients orthogonal to those of the primary precoding vector. The primary stream may include an enhanced control channel E-DPCCH (614) adapted to carry control information associated with both the primary data channel E-DPDCH (624) and the secondary data channel S-E-DPDCH (620).