The disclosure generally pertains to methods and apparatus for on-demand low-power sidelink channel reservation acquisition in wireless communication systems. A WTRU may determine to request on-demand reports related to sidelink resource usage. A WTRU that receives the report may generate a report based on its knowledge of sidelink resource usage. The responding WTRU may determine a priority associated with the report based on the relative amount of information it has regarding the sidelink resource usage. A response window for the response may be determined based on the priority. The responding WTRU then transmits the report in the corresponding response window. If a collision is detected for the report transmission, the response window may be extended and the report may be retransmitted in the extended response window.