Patent ID: 8493899

Claim:
A base station in a wireless communication system, the base station comprising: an adjuster configured to, when a first terminal requests a sleep mode entry including lengths of requested sleep intervals and listening intervals that do not meet a certain condition, adjust the lengths of the sleep intervals and the listening intervals; and a determiner configured to: set a distribution of the sleep intervals and the listening intervals according to the adjusted lengths of the sleep intervals and the listening intervals; and when a second terminal requests the sleep mode entry after the distribution of the sleep intervals and the listening intervals of the first terminal are set, determine a sleep interval among preset sleep intervals having the same length as an initial sleep interval length requested by the second terminal, and determine a sleep mode entry time of the second terminal in a start frame of the determined preset sleep interval, wherein the certain condition is defined according to a length of a sum of a maximum sleep interval and a maximum listening interval is greater than or equal to a length of the sum of remaining sleep intervals and listening interval frames.