Verifying availability of idle-mode mobile subscriber station in wireless access system

A method for power-down of a mobile subscriber station that is in idle-mode, the method comprising:

• transmitting a first request message to a network to enter idle mode;
• receiving a first response message from the network, the first response message including paging information that includes information related to at least paging grouping identification, paging cycle, or paging offset;
• entering idle mode and receiving a paging message during specified time intervals from the network;
• transmitting a ranging request message to the network when attempting to power down so that the network discontinues idle-mode paging control and releases idle-mode retaining information, the ranging request message including information indicating power down;
• and
• receiving a ranging response message from the network, the ranging response message including information related to whether or not the power down location update has been successfully executed.