Poster Abstract: If You Have Time, Save Energy with Pull
  We analyze push and pull for data collection in wireless sensor networks. Most applications to date use the traditional push approach, where nodes transmit sensed data immedi- ately to the sink. Using a pull approach, nodes store the data in their local flash memory, and only engage in commu- nication during dedicated collection phases. We show how one can transform an existing push-based collection protocol into a pull-based one, and compare the power consumption of both approaches on a 35-node testbed. Our results show that substantial energy gains are possible with pull, provided that the application can tolerate a long latency. 
David Hasenfratz, Andreas Meier, Matthias Woehrle, Marco Zimmerling   and Lothar Thiele
cs.NI