Diadem: Prefetch-Based Traffic Shaping for Energy Saving in Wireless Networks

Energy efficiency is critical to wireless networks. Power Saving Mode (PSM) in 802.11 allows wireless devices to sleep periodically to save energy. To assist PSM for better performance, traffic shaping approaches have been leveraged to achieve longer sleep time. Existing traffic shaping solutions mostly delay the data transmission which, however, may fail to deliver data on time due to network dynamics. Instead of delay-based measures, we propose a prefetch-based traffic shaping strategy in this paper. For applications where data requests could be sent in advance (e.g., video streaming), the data is requested in batches, which enables the device to sleep during the rest of time. Our proposal Diadem (Data-in-advance energy-saving mechanism), is more reliable against network churns, and more confidently avoids packets´ missing deadlines. Diadem works where the bandwidth monitor in delay-based solutions is absent, or multiple devices coexist in a wireless LAN. Moreover, Diadem introduces extra chances for improved power saving schemes, such as Suspend-to-RAM. Through simulations, we show that Diadem can help devices to sleep for more than 80% of the running time, while the probability to impact application performance is 50% lower in Diadem (with batch size of 4) than in the delay-based one. We also build a prototype application on a Set-Top Box platform showing the posed programming overhead for developers is acceptable.