  The predominate traffic patterns in a wireless sensor network are many-to-one
and one-to-many communication. Hence, the performance of wireless sensor
networks is characterized by the rate at which data can be disseminated from or
aggregated to a data sink. In this paper, we consider the data aggregation
problem. We demonstrate that a data aggregation rate of O(log(n)/n) is optimal
and that this rate can be achieved in wireless sensor networks using a
generalization of cooperative beamforming called cooperative time-reversal
communication.
