NETWORK SELECTION WITH LOAD MANAGEMENT IN HETEROGENEOUS WIRELESS NETWORKS
AHMED, SYED QUTUBUDDIN
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With the growth of data-capable, multi-interface wireless and mobile devices, a lot of research work is being done on handover management and network selection in heterogeneous environment. Many researchers have proposed several strategies and policies for selecting the appropriate network. These policies di er among each other due to various reasons. The state and load of networks, number and types of wireless networks considered, and preferences of users are some of the reasons that attribute to di erences in those proposed policies. As a result, the applicability and e ciency of those policies depend upon certain situations and circumstances. We propose, in this research, a new concept that will help in utilizing these various policies in a manner that will give better results in a longer run and in various kinds of situations. We have a pool of policies available, and our proposed method will select the policy that is most appropriate according to the current state of user. We modeled this problem as a Markov Decision Process. Since the overall goal is that a user should be able to select an appropriate wireless network according to its service requirements and seamlessly handover to that network regardless of the underlying wireless technology being used. Since di erent sets of methodologies can exist to deal with this issue, we also propose an alternative mechanism that would facilitate a particular user to connect to the most appropriate network in a way that is bene cial to the overall network and its users as a whole. A trusted third party entity receives handover requests from a set of users along with their preferences, takes into consideration current network state of available service providers, and assigns each user to an appropriate network resource. We call this mechanism "Network Assisted Network Selection (NANS)" and it combines network-based, service-based and user-based criteria for network selection, and uses Generalized Assignment Problem (GAP) to assign the network resources to a set of users. ix Mobile Access Gateway (MAG) is a component of Proxy Mobile IPv6 (PMIPv6) which provides network-layer transparent mobility to mobile nodes (MN). MAG serves a local geographical area and mobile nodes in its vicinity may attach to it to get the mobility services from its controlling PMIPV6 domain. Since MAG is the point of attachment of mobile nodes, negotiated and guaranteed quality of service (QoS) is af- fected in case of service disruptions and overload of the MAG. To avoid and minimize the degradation of quality of service, we propose e ective mechanisms to share the load of a ected MAG with the MAG(s) that are working under normal conditions. We propose to handover certain mobile nodes to other MAGs depending upon their geographical serving area and current capacity. Furthermore, location of mobile node, its quality of service pro le, direction of motion and its multi-interface capability are major factors in selecting the mobile nodes for handover.