Improved Algorithms for Data-Gathering Time in Sensor Networks II: Ring, Tree and Grid Topologies

We address the problem of gathering information in sensor webs consisting of sensors nodes, where in a round of communication sensor nodes have messages to be sent to a distant central node (called the base station) over shortest path. There is a wide range of data gathering applications like: target and hazard detection, environmental monitoring, battlefield surveillance, etc. Consequently, efficient data collection solutions are needed to improve the performance of the network. In this paper, we take into account the fact that interference can occurs at the reception of a message at the receiver sensor. In order to save redundant retransmissions and energy, we assume a known distribution of sources (each node wants to transmit at most one packet) and one common destination. We provide a number of scheduling algorithms jointly minimizing both the completion time and the average packet delivery time. We define our network model using directional antennas and consider ring, tree, and grid network (and its generality) topologies. All our algorithms run in low-polynomial time.