is a variation of S-MAC that uses an active period that adapts to traffic
density. Nodes wake up during the beginning of a slot to listen very briefly for activity and
return to the sleep mode when no communication has been observed. When a node transmits,
receives, or overhears a message, it remains awake for a brief period of time after
completion of the message transfer to see if more traffic can be observed. This brief timeout
interval allows a node to return to the sleep mode as quickly as possible. The end effect is
that a node’s awake times will increase with the heavier traffic and will be very brief if traffic
is light