Exploiting Wireless Broadcast Advantage for Energy Efficient Packet Overhearing in WiFi

The energy efficiency of WiFi interfaces has become a significant concern for battery-powered mobile stations. In WiFi networks, a station's backoff procedure is interrupted by other stations' channel activities to receive and decode useless packets that are not intended for it, which consumes a non-negligible amount of its energy. To reduce the energy consumption induced by such packet overhearing, we propose a novel transmission scheme, data symbol silence (DSS), which inserts silent data symbols into the front part of a data packet at the physical layer to encode information. By exploiting the wireless broadcast advantage, the embedded information is received by neighboring stations. Data symbol level energy detection is used to extract the embedded information without receiving and decoding the whole data packet. Thus, unintended receivers can quickly stop useless packet receiving and processing. The signal-to-noise ratio (SNR) gap in current WiFi networks is utilized to ensure the inserted silent data symbols do not affect the correct decoding of the original data packet. We analyze the minimum SNR required for effective DSS and implement DSS to validate its feasibility. Compared with the 802.11 standards, our studies show that DSS significantly improves the energy efficiency of WiFi interfaces.