E-MiLi: Energy-Minimizing Idle Listening in Wireless Networks
E-MiLi: Energy-Minimizing Idle Listening in Wireless Networks
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DOI：
10.1145/2030613.2030637
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发表时间：
2011-09
影响因子：
7.9
通讯作者：
Xinyu Zhang;K. Shin
中科院分区：
文献类型：
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作者：
Xinyu Zhang;K. Shin
众所周知，WiFi接口是移动设备的主要能耗，而空闲监听(IL)是WiFi能耗的主要来源。大多数现有的协议，例如802.11节能模式，都试图通过睡眠调度来减少在IL中花费的时间。然而，通过对真实世界流量的广泛分析，我们发现，即使启用了PSM，也有超过60%的能源消耗在IL中。为了解决这个问题，我们提出了能量最小化空闲监听(E-MILI)，它可以降低IL中的功耗，因为在IL中花费的时间已经通过睡眠调度进行了优化。观察到无线电功率消耗与其时钟频率成比例地下降，E-MILI在IL期间自适应地降低无线电频率，并在检测到传入分组或必须发送分组时恢复到全时钟速率。E-MILI结合了采样率不变检测，即使在接收器的采样时钟速率远低于信号带宽的情况下，也能确保准确的分组检测和地址过滤。此外，它基于与现有MAC层调度协议的简单接口，采用机会主义的降频机制来优化切换时钟速率的效率。我们已经在USRP软件无线电平台上实现了E-MILI。我们的实验评估表明，E-MILI在降频16倍的情况下仍能以接近100%的准确率检测分组。当与802.11集成时，E-MILI可以为实际无线网络中92%的用户降低约44%的能耗。
WiFi interface is known to be a primary energy consumer in mobile devices, and idle listening (IL) is the dominant source of energy consumption in WiFi. Most existing protocols, such as the 802.11 power-saving mode (PSM), attempt to reduce the time spent in IL by sleep scheduling. However, through an extensive analysis of real-world traffic, we found more than 60 percent of energy is consumed in IL, even with PSM enabled. To remedy this problem, we propose Energy-Minimizing idle Listening (E-MiLi) that reduces the power consumption in IL, given that the time spent in IL has already been optimized by sleep scheduling. Observing that radio power consumption decreases proportionally to its clock rate, E-MiLi adaptively downclocks the radio during IL, and reverts to full clock rate when an incoming packet is detected or a packet has to be transmitted. E-MiLi incorporates sampling rate invariant detection, ensuring accurate packet detection and address filtering even when the receiver's sampling clock rate is much lower than the signal bandwidth. Further, it employs an opportunistic downclocking mechanism to optimize the efficiency of switching clock rate, based on a simple interface to existing MAC-layer scheduling protocols. We have implemented E-MiLi on the USRP software radio platform. Our experimental evaluation shows that E-MiLi can detect packets with close to 100 percent accuracy even with downclocking by a factor of 16. When integrated with 802.11, E-MiLi can reduce energy consumption by around 44 percent for 92 percent of users in real-world wireless networks.