Systems, methods, and instrumentalities are disclosed for antenna virtualization, e.g., in at least a two-dimensional antenna array. NE physical antenna elements may be virtualized to Np logical antenna ports. A virtualization may be WTRU-specific, which may optimize MIMO performance. A simplified MIMO scheme may be used with A reduction in feedback, reference signal, and/or control signaling overhead. Antenna virtualization schemes may utilize channel characteristics. Antenna virtualization may be defined, for example, based on antenna port to antenna element mapping, based on a measurement reference signal, based on a codebook or a codebook subset or based on an antenna virtualization matrix. One or more antenna virtualization schemes may be configured in a cell. Antenna virtualization schemes may be configured in a WTRU-specific manner, perhaps for example based on a WTRU channel characteristic(s). A WTRU may report one or more useful (e.g., optimized) antenna virtualization schemes, e.g., based on one or more measurements.