A method for improving
power saving performance of a
mobile station in an IEEE 802.16e
system is provided. The method includes a first process for determining whether a synchronization condition is satisfied, the synchronization condition being that a service connection newly requested to switch to a
sleep mode is low QoS insensitive to
delay and there are one or fewer service connection that is in a
sleep mode and whose
connection type is high QoS sensitive to
delay among other service connections; a second process of transmitting to a
base station a sleep request message for equalizing a
start time of a
sleep mode of the service connection to a
start time of a next
sleep interval of a service connection already in the sleep mode, matching a minimum
sleep interval of the service connection to the next
sleep interval of the service connection already in the sleep mode, and matching a maximum sleep interval of the service connection to a maximum sleep interval of the service connection already in the sleep mode, for sleep-mode synchronization among a plurality of service connections in a
mobile station when the synchronization condition is satisfied; and a third process for switching the service connection to a sleep mode indicated by the sleep request message upon
receipt of a sleep response message from a
base station in response to the sleep request message.