Virtual Backbone-Based Routing in Multihop Ad Hoc Wireless Networks

Recent research ([12][15][19]) shows that the flooding mechanism (for topology update or route request) used in existing protocols for ad hoc wireless networks greatly degrades the network capacity. If we force the effective broadcasts of control packets happen in a small subset of hosts in the network, the protocol overhead caused by global flooding can be substantially reduced. This is the basic idea of virtual backbone-based routing in ad hoc wireless networks, in which all hosts forming the virtual backbone are in charge of control packets dissemination. This strategy works quite effectively in decreasing message overhead. However, constructing a virtual backbone is not trivial. In our study, the virtual backbone is approximated by minimum connected dominating set (MCDS) in unit-disk graphs, which is NP-hard [9]. We propose two distributed time/message efficient approximation algorithms to compute MCDS. Both algorithms have linear message complexities. Algorithm I is cost-aware, which accommodates the strict network resources in virtual backbone construction. Algorithm II is degree-aware, which generates the best result in literature so far to our knowledge. We not only give theoretical performance analysis for both algorithms, but also conduct extensive simulation to compare our algorithms with those in literature. Simulation results and theoretical analysis show that both algorithms perform very well.