Abstract: Methods and systems for enabling MU-MIMO functions on a UE are disclosed. A precoder codebook with precoding matrices can be generated to assist in improving system throughput. Existing specifications designed for two bit precoding information can be used to communicate higher numbers of bits of precoding information by reinterpreting fields described by such specifications. Channel state information can be provided to a base station using several disclosed feedback mechanisms. A UE can determine a current MIMO transmission mode using various implicit and explicit dynamic signaling mechanisms or semi-dynamic signaling where MIMO mode data is received from a higher layer.

Abstract: A wireless-transmit-and-receiving unit (WTRU) supports receiving information via a plurality of multiple-input-multiple-output (MIMO) streams by providing a low-rank feedback report to a base station. The WTRU selects a preferred HS-PDSCH transmission rank, from a subset of ranks that the WTRU supports. The subset includes ranks that are lower than the maximum HS-PDSCH transmission rank supported by the WTRU. For example, for a WTRU that supports rank-4 reception, the subset may include rank-1 and rank-2. The WTRU generates the low-rank feedback report based on the preferred rank, and transmits the report to the base station.