A wireless transmit/receiver unit (WTRU) is configured to receive sounding reference signal (SRS) configuration information. The SRS configuration information indicates a plurality of SRS configurations and indicates antenna transmission information. The WTRU is configured to receive SRS trigger information. The SRS trigger information comprises an indication to trigger transmission of one of the plurality of SRS configurations. The WTRU is configured to transmit a plurality of SRS associated with the indication in the SRS trigger information and based on the SRS configuration information. At least a first SRS of the plurality of SRS is transmitted over a first antenna port in a first symbol and at least a second SRS of the plurality of SRS is transmitted over a second antenna port in a second symbol.