Internal nodes based broadcasting algorithms in wireless networks

In a multihop wireless network, each node has a transmission radius and is able to send a message to one of its neighbors (one-to-one) or all of its neighbors (one-to-all) that are located within the radius. In a broadcasting task, a source node sends the same message to all the nodes in the network. Some existing solutions apply rebroadcasting from each clusterhead or border node in a clustered structure. In this paper, we propose to reduce the communication overhead of broadcasting algorithm by applying the concept of internal nodes. The maintenance of internal nodes requires much less communication overhead than the maintenance of cluster structure of nodes. In one-to-all broadcasting, only internal nodes forward the message, while in the one-toone case messages are forwarded on the edges that connect two internal nodes, and on edges that connect each non-internal node with its closest internal node. Existing notions of internal nodes are improved by using node degrees instead of their IDs (which are used only as secondary keys), and by adding a shortest path criterion. Highest node degrees are also proposed for reducing the number of clusterheads and border nodes in a clustering algorithm. The reduction in communication overhead for broadcasting task, with respect to existing methods, is measured experimentally. Further savings are obtained if GPS and the concept of planar subgraphs are used for one-to-one networks. In case of one-to-all model, GPS may be used to eliminate neighbors that already received the message, and re-broadcast only if the list of neighbors that might need the message is nonempty. The important features of proposed algorithms are their reliability (reaching all nodes in the absence of message collisions), significant savings in the rebroadcasting, and their localized and parameterless behavior.