Seamless vertical handoff using Authentication Certificate in GPRS-WLAN tightly coupled integrated networks

Authentication is a key requirement in security of integrated wireless networks. A Mobile Node (MN) requires to be re-authenticated whenever it performs vertical handoff in integrated wireless networks. The re-authentication causes delay in communication. If MN is not re-authenticated, it causes an even more serious problem of unauthorized entry in a network. In order to solve this problem, we have proposed a scheme for seamless vertical handoff. In proposed scheme, MN performs first authentication and gets an authentication certificate (AC) from home authentication server. The authentication servers of partner network domains share the public keys of each other. Whenever MN wants to switch its network domain, it shows an AC to authentication server of the target network. This AC is encrypted by private key of issuing server. The target network´s authentication server verifies that AC using public key of issuing authority and then authenticates a valid MN. The proposed approach reduces the number of messages, costs less bandwidth for vertical handoff and ensures only authorized entry of a MN from one network to another network.