1. A wireless transmit/receive unit (WTRU) comprising a processor configured to select a pre-coding codeword from a first codebook, the first codebook comprising a plurality of pre-coding codewords divided into a plurality of subsets of pre-coding codewords, wherein the selected pre-coding codeword is selected from a selected one of said subsets of pre-coding codewords, wherein the selected subset is selected based on rank.