In a multihop mobile ad hoc network, broadcasting is an elementary operation to support many applications. Previously, it is shown that naively broadcasting by flooding may cause serious redundancy, contention, and collision in the network, which we refer to as the broadcast storm problem. Several threshold-based schemes are shown to perform better than flooding in that work. However, how to choose thresholds also poses a dilemma between reachability and efficiency under different host densities. In this paper, we propose several adaptive schemes, which can dynamically adjust thresholds based on local connectivity information. Simulation results show that these adaptive schemes can offer better reachability as well as efficiency as compared to the previous results.

In a multihop mobile ad hoc network, broadcasting is an elementary operation to support many applications. In (Ni et al., 1999), it is shown that naively broadcasting by flooding may cause serious redundancy, contention, and collision in the network, which we refer to as the broadcast storm problem. Several threshold-based schemes are shown to perform better than flooding in (Ni et al., 1999). However, how to choose thresholds also poses a dilemma between reachability and efficiency under different host densities. We propose several adaptive schemes, which can dynamically adjust thresholds based on local connectivity information. Simulation results show that these adaptive schemes can offer better reachability as well as efficiency as compared to the results in (Ni et al., 1999).

Broadcasting is a common operation in a network to resolve many issues.In a mobile ad hoc network (MANET) in particular, due to host mobility, such operations are expected to be executed more frequently (such as finding a route to a particular host, paging a particular host, and sending an alarm signal).Because radio signals are likely to overlap with others in a geographical area, a straightforward broadcasting by flooding is usually very costly and will result in serious redundancy, contention, and collision, to which we refer as the broadcast storm problem.In this paper, we identify this problem by showing how serious it is through analyses and simulations.We propose several schemes to reduce redundant rebroadcasts and differentiate timing of rebroadcasts to alleviate this problem.Simulation results are presented, which show different levels of improvement over the basic flooding approach.

In this paper, we propose new routing schemes to perform all-to-all personalized communication (or known as complete exchange) in wormhole-routed, one-port tori. On tori of equal size along each dimension, our algorithms use both asymptotically optimal startup and transmission time. The results are characterized by several interesting features: (1) the use of gather-scatter tree to achieve optimality in startup time, (2) enforcement of shortest paths in routing messages to achieve optimality in transmission time, (3) application of network-partitioning techniques to reduce the constant associated with the transmission time, and (4) the dimension-by-dimension and gather-scatter-tree approach to make possible applying the results to nonsquare, any-size tori. In the literature, some algorithms are optimal in only one of startup and transmission costs, while some, although asymptotically optimal in both costs, will incur much larger constants associated with the costs. Numerical analysis and experiment both show that significant improvement can be obtained by our scheme on total communication latency over existing results.