A major concern for today’s smartphones is their much faster battery drain than traditional feature phones, despite their greater battery capacities. The difference is mainly contributed by those more powerful but also much more power-consuming smartphone components, such as the multi-core application processor and the high-definition (HD) display. While the application processor must be active when any smart apps are being used, it is also unnecessarily waken up, even during idle periods, to perform operations related to basic phone functions (i.e., incoming calls and text messages). In addition, the power-hungry HD display is also used unnecessarily for such basic functions. In this article, we investigate how to increase the battery life of smartphones by minimizing the use of application processor and HD display for operations related to basic functions. We find that the application processor is often waken up by a process running on it, called the Radio Interface Layer Daemon (RILD), which interfaces the user and apps to the GSM/LTE cellular network. In particular, we demonstrate that a great amount of energy could be saved if RILD is stopped, such that the application processor can sleep more often. Based on this key finding, we design a Smart On Demand (SOD) configuration that reduces the smartphone energy consumption by running RILD operations on a secondary low-power microcontroller and by using a secondary low-power display to interface the user with basic functions. As a result, basic phone functions can be handled at much lower energy costs and the power-consuming components, i.e., application processor and HD display, are waken up only when one needs to use any smart apps, in an on-demand manner. We have built a hardware prototype of SOD and evaluated it with real user traces. Our results show that SOD can increase its battery life by up to 2.5 more days.

中文翻译：

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草皮

当今智能手机的一个主要问题是它们比传统功能手机更快的电池消耗，尽管它们的电池容量更大。差异主要来自那些功能更强大但功耗更高的智能手机组件，例如多核应用处理器和高清 (HD) 显示器。虽然在使用任何智能应用程序时应用程序处理器必须处于活动状态，但它也不必要地被唤醒，即使在空闲期间，以执行与基本电话功能相关的操作（即，来电和短信）。此外，这些基本功能也不必要地使用耗电的高清显示器。在本文中，我们研究如何通过最大限度地减少使用应用处理器和高清显示器来进行与基本功能相关的操作，从而延长智能手机的电池寿命。我们发现应用程序处理器经常被一个运行在其上的进程唤醒，该进程称为无线电接口层守护进程 (RILD)，它将用户和应用程序连接到 GSM/LTE 蜂窝网络。特别是，我们证明如果停止 RILD，可以节省大量能量，从而应用处理器可以更频繁地休眠。基于这一关键发现，我们设计了一种智能按需 (SOD) 配置，该配置通过在辅助低功耗微控制器上运行 RILD 操作并使用辅助低功耗显示器将用户与基本功能连接起来，从而降低智能手机的能耗。因此，基本的电话功能可以以低得多的能源成本处理，并且仅在需要使用任何智能应用程序时以按需方式唤醒耗电组件，即应用处理器和高清显示器。我们已经构建了 SOD 的硬件原型，并使用真实的用户跟踪对其进行了评估。我们的结果表明，SOD 可以将其电池寿命延长多达 2.5 天。