Ø Idea: switch the transceiver off if not needed
Ø States of a station: sleep and awake
Ø Timing Synchronization Function (TSF)
q stations wake up at the same time
Ø Infrastructure
q Traffic Indication Map (TIM) list of unicast receivers transmitted by AP
q Delivery Traffic Indication Map (DTIM) list of broadcast/multicast receivers transmitted by AP
Ø Ad-hoc
q Ad-hoc Traffic Indication Map (ATIM) announcement of receivers by stations buffering frames
more complicated - no central AP collision of ATIMs possible (scalability?)