  Many sensor applications are interested in computing a function over
measurements (e.g., sum, average, max) as opposed to collecting all sensor
data. Today, such data aggregation is done in a cluster-head. Sensor nodes
transmit their values sequentially to a cluster-head node, which calculates the
aggregation function and forwards it to the base station. In contrast, this
paper explores the possibility of computing a desired function over the air. We
devise a solution that enables sensors to transmit coherently over the wireless
medium so that the cluster-head directly receives the value of the desired
function. We present analysis and preliminary results that demonstrate that
such a design yield a large improvement in network throughput.
