Hierarchical Structure for Supporting Movable Base Stations in Wireless Networks

Wireless networks with movable base stations combine the advantages of mobile ad hoc networks and wireless LAN to achieve both flexibility and scalability. We present the hierarchical mobile wireless network (HMWN) to support movable base stations. HMWN may be applied to ad hoc networks as well to build a virtual hierarchy. In such a system, mobile hosts are organized into hierarchical groups. Four basic operations for setting up and maintaining the network structure are grouping, registration, leaving, and migration. An efficient group membership management protocol is developed to support mobile hosts roaming among different groups. The segmented membership-based group routing (SMGR) protocol is proposed to take advantage of the hierarchical structure and membership information. In this protocol, only local message exchanging is required for maintaining network topology and routing information. Simulation-based experiment demonstrates the scalability of the design in terms of protocol overheads.