Graph Partitioning Problem Applied to Adaptive Mobile Wireless Networks

In a large-scale adaptive mobile wireless network, long-distance message transfer can be routed by introduced mobile servers while nearby mobile units can contact each other through direct constructed communication channels. In order to achieve scalability by direct connection among mobile units and reliability sustained by mobile servers for QoS, a mixed wireless infrastructure incorporating mobile servers and ad hoc communications is investigated. A cluster of mobile units can be modelled as a mobile node. Both mobile nodes and servers are free of movement under the adaptive mobile wireless networks. In this paper, two graph models are introduced to represent mobile node communication requirements as well as mobile server configurations. The dynamically changed topology for mobile nodes and mobile servers together with other constraints (e.g., transmission range, bandwidth) make the assignment of mobile nodes to mobile servers difficult. Such assignment can be formalized as the partition problem, which is proved to be NP-complete to attain optimal solutions. Based on the generated two modelling graphs, polynomial-time algorithms are developed to the partitioning problem such that the communication among different mobile nodes are successfully switched by mobile servers. The experimental environment simulates the dynamically modified network topology of a wireless network consisting of roaming mobile nodes. The simulation results show that the proposed techniques yield good assignments with similar performance as those produced by exhaustive approaches.