Mobility management in heterogeneous access networks

This thesis proposes, describes and validates solutions to enhance mobility in heterogeneous access networks. Wireless access networks have become available almost everywhere and current research strives to make them pervasive. Users having wireless access to the Internet are driving the demand for mobile and heterogeneous solutions where services could be accessed from anywhere, any time and from any device. Future wireless connectivity will be provided through a mix of coexisting heterogeneous access network technologies. To enhance mobility in heterogeneous networks this thesis focuses on mobility management systems and connectivity of wireless multi-hop ad hoc networks to the Internet. In a wireless environment with overlapping service areas, mobile nodes need to select which gateway(s) to use to access the wireless infrastructure. The metrics used to select the point of attachment within an access technology are insufficient to compare the capacity of different technologies or multi-hop routes. This thesis proposes, describes and validates solutions to calculating network layer metrics and using them in gateway selection and handover decisions. To enable connectivity of a mobile ad hoc network (MANET) to the Internet, a gateway must bridge the wired single-hop and wireless multi-hop approaches. A MANET enables connectivity to more than one gateway at a time and combined with multihoming it provides seamless handover between subnets. The gateway selection and handover decisions are complicated by the multihoming capabilities. Connectivity to Internet services makes it important to maintain the efficient route to the gateway. It is also important to identify the location of a destination to separate the management of Internet and intra MANET destinations. This thesis proposes,describes and validates solutions to deploying multihomed mobility into MANETs and thereby handling multi-hop gateway discovery, registration of multiple gateways and tunneling to selected gateway(s). The solution maintains gateway connectivity in MANETs by installing routes to gateways using advertisements and manages route discovery based on the destination locality. Both applications with mobility awareness (e.g. SIP phones) and those without it must be supported by a mobility management system. The existence of network layer mobility management can enhance an application layer system. This thesis proposes, describes and validates deployment of a mobility management system with support of both application and network layer mobility. With wireless access networks some technologies might not support some types of applications and a single technology might not cope with all the application demands from a mobile node. Thus the control of individual traffic flows could be used to share the load on multiple access technologies and to direct flows over specified technologies. This thesis proposes, describes and validates solutions to identification and mobility management of individual traffic flows in a heterogeneous network environment. Finally this thesis proposes, describes and validates a deployment proposal of route evaluation and flow control to enable load balancing in wireless multi-hop networks.Godkänd; 2007; 20071121 (ysko