  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.
