he disparity of existing networks (2G, 3G, WLAN, WiMAX, etc.) limits the service accessibility by mobile users to access-specific terminals and individual subscriptions. To offer "always connectivity" anytime and anywhere, it is necessary to formulate a mechanism that promotes interoperability among these networks and supports seamless mobility through a single handheld terminal, capable of configuring to any network. A paradigm shift from a circuitswitched to a packet-based network is required in order to streamline the merging of wireless networks with the global Internet. As a precursor of the packet network, Internet Protocol (IP) needs to be adopted as the underlying transport technology to support the growing number of wireless users, new applications, and addressing requirements. Next generation mobile network (NGMN) offers such an integrated end-to-end IP-based infrastructure. Contrary to some other definitions of the next generation network, where it is perceived as a new technology/network with high-data-rate capabilities (considerably higher than present networks), we consider NGMN -at times also referred to by the networking jargons NGN, 4G, or beyond 3G (B3G) -to be an integration of all existing and emerging wireless networks through a common platform (IPv6 based packet network). Such integration will allow existing networks to evolve independently (possibility to achieve higher data rate through modification of radio and core network) and enable new/emerging networks to seamlessly connect to the general framework. A multimode (preferably software-defined radio based reconfigurable) terminal [1] is expected to provide access to network-independent services.Since each individual network has its own unique characteristics (e.g., radio spectrum, multi-access system, signaling, etc.) and application QoS requirements (e.g., bandwidth, data rate, delay, BER, etc.), facilitating interoperability within the NGMN framework raises several key design issues, mainly NGMN functional architecture, cross-layer coordination within the protocol stack, mobility management (in particular, vertical handoff), and resource management (in particular, admission control). On the part of a network designer, adequately addressing these issues are of paramount importance to the successful deployment of NGMN. In this article we resolve these design attributes by proposing appropriate solutions. NGMN Functional ArchitectureFor interoperability, networks or devices are represented by the seven-layer ISO-OSI model or TCP/IP protocol stack as a means of ensuring conformance. Due to the heterogeneity of networks and their offered services, corresponding layered architectures exhibit different features which culminate from their service policy and supported traffic profiles. For example, within Global System for Mobile Communications (GSM) architecture (circuit-switched and optimized for voice) radio link layer assumes greater importance whereas adaptive higher layers play pivotal role in high-data-rate WLAN. Universal Mobile Telecom...

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Despite well-defined security models to prevent fraudulent intrusion, a number of security attacks have been reported in literature for legacy networks. While a section of these attacks are due to inherent design limitations, others stem from the pervasive introduction of Internet Protocol (IP)-based applications and external attacks. The former can be addressed by the continual evolution of the system (as is the case with existing systems) whereas the latter requires careful designing. With the advent of all-IP next generation mobile network (NGMN) inter-connecting disparate access technologies, the design process assumes paramount importance in relation to detecting/preventing/eliminating migration of attacks through infected terminals. Taking into consideration the fact that standardization bodies are responsible for individual network evolution, a cooperative NGMN security architecture is proposed in this paper that identifies and isolates/eliminates security attacks. The cooperation is encased by the network elements within the NGMN hierarchy and utilizes an anomaly-based attack detection mechanism. Several dominant security attacks are simulated to demonstrate the effectiveness of the proposed architecture.