1. Technical Field
The present invention generally relates to mobile networks and, more particularly, to assigning gateways for heterogeneous wireless mobile networks.
2. Description of the Related Art
Inter-domain networking across mobile ad hoc networks is an important capability to enable practical applications, such as search and rescue operations by multi-agencies, disaster recovery efforts by multi-national organizations (such as the RED CROSS, the MEDECINS SANS FRONTIERES, law enforcement), and coalition military operations by multiple forces in a region with little infrastructure support. Inter-domain networking allows different organizations with potentially heterogeneous networking technologies to communicate with each other while preserving the organizational boundaries and their own networking policy. In recent years, the research community started to pay attention to this important yet relatively unexplored problem, and several proposals have been made to address technology gaps. The proposals involve the following: architecture and framework design; inter-domain routing and policy support; and deployment and control of helper nodes to connect multiple domains.
One of the key components to enable inter-domain networking (in both wired and wireless networks) is the gateway. Gateway nodes act as control points to collect and distribute inter-domain routing information, and also enforce inter-domain routing policy enacted by each domain. In addition, gateways play the important role of isolating the intra-domain routing mechanism of one domain from that of other domains. More importantly, in mobile ad hoc networks (MANETs), gateways may need to perform protocol translation since different domains may employ different routing schemes (e.g., reactive, proactive, geo-routing, and so forth). General issues in designing an inter-domain routing protocol in MANETs and building gateways have been presented.
Previous work assumed gateway functionalities are statically assigned to a subset of nodes. While this approach will work well in a static scenario (e.g., wireless mesh), it may be problematic in MANETs due to node mobility. FIGS. 1-4 show an example of network topology changes in MANETs. FIG. 1 shows the initial network topology 100 of a particular MANET. FIG. 2 shows the network topology 200 of the particular MANET after nodes in partition B have moved. FIG. 3 shows the network topology 300 of the particular MANET after a network partition (two nodes in Partition A moved away). FIG. 4 shows the network topology 400 of the particular MANET after regaining cross-partition connectivity. Returning to FIG. 1, there are two partitions, and each partition has a gateway through which the nodes in one partition can communicate with the nodes in the other partition. At some later time, the network topology has changed due to node mobility or wireless channel variation and, as a result, the inter-partition connectivity is lost (FIGS. 2 and 3). In general, any static gateway assignment is bound to suffer from such connectivity problem in dynamic MANETs.