Patent ID: 7912467

Claim:
A system for controlling a power saving mode of a subscriber station in a wireless portable Internet system, the system comprising: a message receiver for receiving a sleep request message from the subscriber station; a message parser for parsing the sleep request message and extracting an initial sleep window that is an initial sleep window value when the subscriber station enters a sleep mode, a final sleep window that is a maximum sleep window when the subscriber station enters the sleep mode, and a subscriber station identifier; a sleep mode controller for determining an entrance time to the sleep mode by the subscriber station which requests the sleep mode according to the initial sleep window, the final sleep window, and the subscriber station identifier for group listening intervals of a plurality of subscriber stations; a grouping database for storing information on sleep modes of the grouped subscriber stations and information on the grouped subscriber stations; a sleep mode database for storing initial sleep windows and final sleep windows of the grouped subscriber stations; and a message transmitter for notifying the sleep-mode-requested subscriber station of the initial sleep windows, the final sleep windows, and the entrance time to the sleep mode.