Modified hybrid coupled architecture for UMTS-WiMAX-WLAN overlay networks using IMS

4G communications expects to integrate different radio access networks together to meet wide expectation from users and to support mobility. The different radio networks such as Universal Mobile Telecommunication Systems (UMTS), Worldwide interoperability for Microwave Access (WiMAX), Wireless Local Area Network (WLAN), etc. are collocated in same geographical area to provide different services are called overlay networks. Integration of these networks increases efficient utilization of overall network bandwidth, QoS of user and supports mobility. Integration of different networks has the challenges like terminal mobility, session establishment, session management, session negotiation and charging etc. The IP Multimedia Subsystem (IMS) offers solution for above mentioned issues. This paper proposes modified hybrid coupled architecture for UMTS-WIMAX-WLAN overlaid network using IMS to support QoS and mobility. Performance of the proposed modified hybrid coupled architecture for two real time services (voice and video) are compared with loose, tight and hybrid coupled architectures. Packet delay variation, packet end- to-end delay for video service, jitter, packet end-to end delay, Mean opinion score (MoS) value for voice service and number of hops and network convergence activity are considered as parameters for performance comparison. The proposed modified hybrid coupled architecture provides better QoS compared with loose, tight and hybrid coupled architecture.