Abstract— The major trend in next-generation or 4G wireless networks (NGWN/4G) is the coexistence of diverse but complementary architectures and wireless access technologies. In this context, an appropriate integration and interworking of existing wireless networks are crucial to allow seamless roaming across those networks. Several integrated architectures have been proposed for 3G cellular networks and wireless local area networks (WLANs) by both third generation wireless initiatives, 3GPP and 3GPP2. However, the proposed architectures have several drawbacks, the most significant being the absence of quality of service (QoS) guarantees, seamless roaming and service continuity. This paper proposes a novel architecture, called Integrated InterSystem Architecture (IISA), which enables the integration and interworking of various wireless networks and hide their heterogeneities from one another. The IISA architecture aims provisioning of guaranteed seamless roaming and service continui...