Wireless Sensor and Actuator Networks: Algorithms and Protocols for Scalable Coordination and Data Communication

2.7 PARAMETERLESS BROADCASTING FOR DELAY TOLERANT-NETWORKS

Existing broadcasting protocols can be CDS-based protocols for static networks, blind flooding for moderately mobile networks and Hyper-flooding (Viswanath and Obraczka, 2002) for highly mobile and frequently partitioned networks. In static networks, nodes do not move or they move slowly, such that network topology does not change during broadcasting. However, the line separating moderately mobile networks and highly mobile networks is often thin. Generally speaking, the difference is based on the percentage of neighbor changes for a node during broadcasting. A network is moderately mobile if each node is either static or moderately mobile. Thus, a network is moderately mobile even if there is a single moderately mobile node among static nodes in the network. A network is highly mobile if at least one of its nodes is highly mobile. Therefore, a network with a few high-speed vehicles and a lot of pedestrians along the road is highly mobile (Khan et al., 2008).

Broadcasting protocols for static networks have been discussed in previous sections. Since the maintenance of neighbor knowledge is expensive or even impossible in mobile networks, blind flooding can still be applied in moderately mobile networks. However, it may not suffice in networks with temporary partitions and high mobility. This is due to the fact that each node in the network retransmits the broadcasting message only once and stops retransmission even if it ...