A Unified Mobility Management Architecture for Interworked Heterogeneous Mobile Networks

The buzzword of this decade has been convergence: the convergence of telecommunications, Internet, entertainment, and information technologies for the seamless provisioning of multimedia services across different network types. Thus the future Next Generation Mobile Network (NGMN) can be envisioned as a group of co-existing heterogeneous mobile data networking technologies sharing a common Internet Protocol (IP) based backbone. In such all-IP based heterogeneous networking environments, ongoing sessions from roaming users are subjected to frequent vertical handoffs across network boundaries. Therefore, ensuring uninterrupted service continuity during session handoffs requires successful mobility and session management mechanisms to be implemented in these participating access networks. Therefore, it is essential for a common interworking framework to be in place for ensuring seamless service continuity over dissimilar networks to enable a potential user to freely roam from one network to another. For the best of our knowledge, the need for a suitable unified mobility and session management framework for the NGMN has not been successfully addressed as yet. This can be seen as the primary motivation of this research. Therefore, the key objectives of this thesis can be stated as: To propose a mobility-aware novel architecture for interworking between heterogeneous mobile data networks To propose a framework for facilitating unified real-time session management (inclusive of session establishment and seamless session handoff) across these different networks. In order to achieve the above goals, an interworking architecture is designed by incorporating the IP Multimedia Subsystem (IMS) as the coupling mediator between dissipate mobile data networking technologies. Subsequently, two different mobility management frameworks are proposed and implemented over the initial interworking architectural design. The first mobility management framework is fully handled by the IMS at the Application Layer. This framework is primarily dependant on the IMS’s default session management protocol, which is the Session Initiation Protocol (SIP). The second framework is a combined method based on SIP and the Mobile IP (MIP) protocols, which is essentially operated at the Network Layer. An analytical model is derived for evaluating the proposed scheme for analyzing the network Quality of Service (QoS) metrics and measures involved in session mobility management for the proposed mobility management frameworks. More precisely, these analyzed QoS metrics include vertical handoff delay, transient packet loss, jitter, and signaling overhead/cost. The results of the QoS analysis indicates that a MIP-SIP based mobility management framework performs better than its predecessor, the Pure-SIP based mobility management method. Also, the analysis results indicate that the QoS performances for the investigated parameters are within acceptable levels for real-time VoIP conversations. An OPNET based simulation platform is also used for modeling the proposed mobility management frameworks. All simulated scenarios prove to be capable of performing successful VoIP session handoffs between dissimilar networks whilst maintaining acceptable QoS levels. Lastly, based on the findings, the contributions made by this thesis can be summarized as: The development of a novel framework for interworked heterogeneous mobile data networks in a NGMN environment. The final design conveniently enables 3G cellular technologies (such as the Universal Mobile Telecommunications Systems (UMTS) or Code Division Multiple Access 2000 (CDMA2000) type systems), Wireless Local Area Networking (WLAN) technologies, and Wireless Metropolitan Area Networking (WMAN) technologies (e.g., Broadband Wireless Access (BWA) systems such as WiMAX) to interwork under a common signaling platform. The introduction of a novel unified/centralized mobility and session management platform by exploiting the IMS as a universal coupling mediator for real-time session negotiation and management. This enables a roaming user to seamlessly handoff sessions between different heterogeneous networks. As secondary outcomes of this thesis, an analytical framework and an OPNET simulation framework are developed for analyzing vertical handoff performance. This OPNET simulation platform is suitable for commercial use

Microscopic and morphometric study on the epididymis of Sri Lankan cattle

Epididymides were collected from five mature healthy indigenous bulls and brought to the laboratory in ice. Tissue sections were taken from six different areas; two (proximal and distal) from each head, body and tail regions of the epididymis, processed and stained with Haematoxylin& Eosin (H&E) or Van-Gieson to study the microscopic anatomy and morphometry. The volume densities of the epididymal duct, ductular lumen, epithelium, and the intestitium were measured. The tubular and lumen diameters and heights of the epithelium and stereo cilia were also measured. The commonest cell type found was principal cells with steriocilia. The basal cells, the second abundant cell type, found closer to the basement membrane of the tubules and rich in the body region. The apical cells were located closer to luminal surface of the duct. The halo cells were the least common cell type observed. The smooth muscle layers that encircle epididymal duct increase its thickness from head to tail direction. The volume density of epididymal duct was high in head and tail region compare with that of body region. The epithelial volume density decreased from head to tail direction and the opposite was observed for the luminal volume density. The tubular diameter found to be similar in all six regions except proximal tail which had the highest diameter (5.9 mm). The decrease of the epithelial height from head to tail direction contributed for the increase of the luminal diameter in the same direction. The height of stereocilia was found low in the distal head (1.2 mm) and distal tail (1.4 mm) region compare to the rest of the regions. Four types of cells namely principal cells, halo cells, basal cell and epical cells, are present in the epididymal duct. The sperm storage area in the tail of the epididymis is increased due to an increase in the luminal diameter caused by a decreased in epithelial height and length of stereocilia