Inexpensive sensors capable of significant computation and wireless communications are becoming available [2,4]. A web of sensor nodes can be deployed to collect useful information from the field, for example, in harsh physical environments [13]. These sensor nodes collect audio, seismic, and other types of data and collaborate to perform a high level task in the network. Sensor nodes are severely constrained by the amount of battery power available, limiting the lifetime and quality of the network. Since wireless communications consume significant amounts of battery power, sensor nodes should spend as little energy as possible receiving and transmitting data [5,10,12]. It is necessary for communication protocols to maximize nodes’ lifetimes [9], reduce bandwidth consumption by using local collaboration among the nodes, and tolerate node failures [14]. Figure 1 shows a 100-node sensor network in a play field of size 50m x 50m. A typical application in a sensor web is gathering of sensed data at a distant base station (BS) [3]. Each sensor node has power control and the ability to transmit data to any other sensor node or directly to the BS [6,7]. We assume that all nodes have location information about all other nodes. However, if this were not the case, our scheme would still work. Nodes would have to expend some extra energy to find their close neighbors. They could do this by sending with enough power to signal a node, and then gradually reduce its power to find which neighbor is closest to it. In this paper, our model sensor network has the following properties: