A wireless transmit/receive unit, WTRU, in communication with a communication network, the WTRU comprising: a memory (130, 132); a processor, the processor configured at least to: determine to request one or more system information, SI, messages from the communication network; conduct a beam sweep operation of one or more downlink, DL, beams transmitted from the communication network; identify at least one DL beam of the one or more DL beams via which to receive the one or more on-demand SI messages based at least in part on the beam sweep operation; determine one or more uplink, UL, resources with which to communicate information for a WTRU reception of the one or more on-demand SI messages, the information for the WTRU reception including the at least one DL beam; and initiate the request for the one or more on-demand SI messages from the communication network; and a transceiver, the transceiver configured at least to: send the request for the one or more on-demand SI messages to the communication network using the one or more UL resources, the request including the information for the WTRU reception of the one or more on-demand SI messages; and receive at least one of the one or more on-demand SI messages from the communication network via the at least one DL beam. a memory (130, 132); a processor, the processor configured at least to: determine to request one or more system information, SI, messages from the communication network; conduct a beam sweep operation of one or more downlink, DL, beams transmitted from the communication network; identify at least one DL beam of the one or more DL beams via which to receive the one or more on-demand SI messages based at least in part on the beam sweep operation; determine one or more uplink, UL, resources with which to communicate information for a WTRU reception of the one or more on-demand SI messages, the information for the WTRU reception including the at least one DL beam; and initiate the request for the one or more on-demand SI messages from the communication network; and determine to request one or more system information, SI, messages from the communication network; conduct a beam sweep operation of one or more downlink, DL, beams transmitted from the communication network; identify at least one DL beam of the one or more DL beams via which to receive the one or more on-demand SI messages based at least in part on the beam sweep operation; determine one or more uplink, UL, resources with which to communicate information for a WTRU reception of the one or more on-demand SI messages, the information for the WTRU reception including the at least one DL beam; and initiate the request for the one or more on-demand SI messages from the communication network; and a transceiver, the transceiver configured at least to: send the request for the one or more on-demand SI messages to the communication network using the one or more UL resources, the request including the information for the WTRU reception of the one or more on-demand SI messages; and receive at least one of the one or more on-demand SI messages from the communication network via the at least one DL beam. send the request for the one or more on-demand SI messages to the communication network using the one or more UL resources, the request including the information for the WTRU reception of the one or more on-demand SI messages; and receive at least one of the one or more on-demand SI messages from the communication network via the at least one DL beam.