Extended mobile IP and support for global connectivity in hybrid networks

Abstract: Mobility is an essential and necessary feature for roaming users who connect to wireless networks via access points. Access points may have different capabilities, be connected to different networks and be installed by different providers. A mobile host will discover multiple access points in this environment. A mobile host should be able to use the best available connectivity to communicate with a correspondent host and perhaps use multiple connections for different hosts. In areas with wireless local area network access, pockets with limited or no coverage could exist. Such restricted connectivity could be compensated by neighbor hosts who form an ad hoc network and relay packets until they reach an access point. This thesis describes and discusses the proposed solutions towards enabling and supporting connectivity in wireless access networks. In the proposed solutions the network layer software will evaluate and decide which wireless network connections to use. This thesis proposes a Running Variance Metric (RVM) and a Relative Network Load (RNL) as performance metrics to classify the traffic load of access points in wireless access networks. RVM and RNL can be efficiently used for infrastructure networks and ad hoc networks. This thesis proposes an extension to Mobile IP in order to enable mobile hosts to use multiple care-of addresses simultaneously. These extensions enhance network connectivity by enabling the mobile host, the home agent and correspondent hosts to evaluate and select the best connection. The proposed extension to Mobile IP is called Multihomed Mobile IP to emphasize support for multiple connections for a mobile host at the same time. This thesis describes a proposed gateway architecture that integrates wired IP networks with ad hoc networks. Routes between a mobile host and gateways are maintained continuously where multi-hop ad hoc connections are supported. Communication between peers in ad hoc networks is based on reactive ad hoc routing. Mobile hosts moving between ad hoc networks are supported by Multihomed Mobile IP. This thesis describes developed prototypes and simulation results to validate multihomed Mobile IP and the gateway architecture which integrates ad hoc networks and wired IP networks.