Date Added: Nov 2009
This paper proposes an energy efficient Medium Access Control (MAC) protocol for wireless sensor networks, called Energy Saving Token Ring Protocol (ESTR). ESTR bases on the well-known token ring protocol. The sensor nodes are connected in rings where only the node that holds the token is active and able to communicate. ESTR establishes sleep times for sensor nodes that don't need to send or receive messages. Thus, nodes save energy spending less time in active mode. Also ESTR minimizes energy wasted due to idle-listening and overhearing.