We observed that system performance is strongly dependent on the level of interworking between the various protocols and software modules, e.g., SIP modules, DHCP modules, WLAN device driver, etc.
To enable ubiquitous services, there have been intensive studies on the interworking between the complementary 3G cellular networks and WLANs by means of vertical handoff, access selection, and load balancing [1, 2].
These include for instance a module taking care of interworking between CoAP/UDP/IP and the ZigBee protocol stack.
In this scenario, the deployment of innovative wireless data networks, the integration with the Internet and the interworking between different wireless technologies, typically 2.5/3G cellular and Wireless LAN (WLAN), will be challenging objectives for competitive service providers.
Furthermore, the WLAN standardization community has been working on the improvement of the interworking between 3GPP and WLAN networks.
The paper discusses solutions to permit the interworking between MA platforms and other systems, even non-MA-based, via compliance with either accepted or emerging interoperability standards.
The industry have also developed architectures to facilitate interworking between fixed network and the wireless networks [8].
Then, as a example, the interworking between common object request broker architecture (CORBA) component model (CCM) and enterprise Java bean (EJB) is discussed in detail.
Recently, the interworking between 3G cellular networks and wireless local area networks (WLANs) has become a global trend in wireless communications because of the fact that these networks exhibit characteristics such as wide coverage and high data rates that mutually complement each other.
Through the adoption of the Parlay APIs, a way is foreseen for (a) consolidation of telephone service over both Internet and PSTN through the imposition of a uniform call control API while allowing the installed IN infrastructure to be used also for Internet telephony services and (b) for service interworking between telephony-like services and open distributed services in the Internet.
Interworking between SIP and H.323 is essential to ensure full end-to-end connectivity through the network, although the current number of deployed commercial SIP endpoints is relatively small compared to widely deployed H.323 endpoints.
