Securing Roaming and Vertical Handover between Mobile WiMAX and UMTS

Handover between different wireless mobile networks is a key constraint for achieving subscribers satisfaction and enhancing the overall performance. More precisely, mobile subscribers wish to enjoy ubiquitous service availability while being sure of keeping the required security level and a comparable performance level when changing the aceess network. In this paper, we address this issue by proposing a new authentication protocol that enables mobile WiMAX subscribers who do not possess USIM cards to transparently roam and handover to UMTS networks and vice-verca.