Reference signal design and device procedures for downlink-based positioning/ranging using multi-frequency phase difference of arrival

A wireless transmit/receive unit (WTRU) configured to communicate through a zero energy (ZE) interface, the WTRU comprising:

• a transceiver;
• and
• a ZE transceiver;
• the transceiver configured to receive a message indicating a plurality of positioning reference signal (PRS) configurations, wherein each PRS configuration provides frequency and time resources for reception, by the WTRU, of a plurality of PRSs, and wherein the message indicates a default PRS configuration;
• upon a condition that the default PRS configuration is not suitable for one or more capabilities or requirements of the WTRU, transmit a message including a request to use another one of the plurality of PRS configurations, wherein the another one of the plurality of PRS configurations is requested based on the one or more capabilities or requirements of the WTRU;
• and
• receive a message indicating ranging assistance information applicable during a time duration;
• the ZE transceiver configured to receive, within the time duration, the plurality of PRSs using the another one of the plurality of PRS configurations and using the indicated ranging assistance information;
• and
• the transceiver configured to transmit a report indicating a range estimate that meets a required accuracy, wherein the range estimate is based on a phase difference of arrival (PDOA) of the received plurality of PRSs.