US Patent 7844815 Method and communication system for controlling security association lifetime

An apparatus and method for selecting a security association timer between user equipment and a control entity in a communication system are disclosed. The apparatus includes a transmitter configured to transmit a registration request message to a control entity in a communication system, whereby the registration request message is configured to request registration with the control entity. The apparatus further includes a receiver configured to receive an authentication challenge including a temporary timer, whereby the temporary timer is configured to set a time duration for the apparatus to respond to the authentication challenge. The receiver is further configured to receive an acknowledgement message including a security association timeout value in response to the transmitted registration message, whereby the security association timeout value includes a set time length of a security association equal to a registration time length set for registration of the apparatus. The transmitter is further configured to transmit a registration authentication message to the control entity before expiration of the temporary timer.