Patent ID: 8731194

Claim:
A method of establishing security association before an inter-RAT (Radio Access Technology) handover with a target base station (TBS) included in a heterogeneous radio access network is performed, the method comprising: transmitting, by a mobile station (MS) to a serving base station (SBS), a subscriber station basic capability request (SBC-REQ) message to negotiate capabilities for the inter-RAT handover; receiving, by the MS from the SBS, a subscriber station basic capability response (SBC-RSP) message in response to the SBC-REQ message, the SBC-RSP message including an inter-RAT parameter indicating that the SBS supports the inter-RAT handover with the heterogeneous radio access network; transmitting, by the MS to the SBS, a PKM (Privacy Key MAC (Media Access Control)) request message requesting the SBS to transfer authentication related information of the MS to a target network authentication server in the heterogeneous radio access network; and receiving, by the MS from the SBS, a PKM response message before the inter-RAT handover with the TBS is performed, the PKM response message including authentication related information to be used in the heterogeneous radio access network, wherein the inter-RAT handover is performed between heterogeneous radio access networks.