A method and an apparatus are provided for efficient transmission of low-data-rate packet services in a multiple-input multiple-output (MIMO) mode of operations in the presence of high-data-rate packet services. Precoding weight information (PWI) is signaled implicitly to a wireless transmit receive unit (WTRU). A precoding weight vector is signaled in a high speed shared control channel less (HS-SCCH-less) transmission using a new HS-SCCH type P. This explicit PWI signaling approach transmits the PWI with minimum power overhead. The data carried in the HS-SCCH type P is encoded to minimize the required transmitted power. A channel type HS-SCCH type 2M is also described.
