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Today, personal computing is shifting from traditional desktop computers to mobile devices, such as MP3 players, PDAs and cellular phones. Companies like Nokia, Samsung, Google and Apple have spurred innovation such that today, smartphones come standard with touch screens, GPS, cameras, as well as a whole suite of connectivity options. Moreover, mobile devices will continue to advance in the coming years. The capabilities that seem high-end today will be standard fare in the next generation of devices and basic requirements in even later devices.
However, the dark side of Moore’s Law is the waste caused by our society’s insatiable desire to frequently upgrade our mobile devices. The typical cellular handset is discarded after only 18 months, and Nokia alone sells over 1 million handsets a day. Over 120,000 pre-orders were made in the first day that Apple’s iPad was announced, and over 300,000 iPads were sold in the first day that they were sold in stores. The environmental impact of this stream of handsets in terms of manufacturing energy, materials and disposal costs is alarming.
Traditional approaches of recycling phones simply extract materials or components from used phones to build other devices. However, used smartphones are usually functional and powerful enough to continue work for a long time. It would be a waste to recycle smartphones after they are discarded. On the other hand reusing tries to use the same device as a complete functional unit for the same or different purposes. For example, lots of used smartphones are refurbished and sold again. Geyey, Oliver, Amirtarajah, Akella, and Chong (2007) investigates reusing embedded microprocessors, showing that the energy required to manufacture a processor far out-strips the energy consumed during the processor’s lifetime for most low-power embedded processors. Hence repurposing retired mobile devices can significantly amortize production energy of these devices and reduce their environmental impact.
Even if we believe that it is more environmentally friendly and feasible to reuse mobile phones, we need to find a market for these mobile phones. We argue that use in educational classrooms is a promising candidate for reused smartphones, given the potential benefits to elementary school students who may not commonly own cellular phones (or are forbidden from having them in school). Note that we focus on repurposing smartphones in non-phone applications and expect cellular calling capabilities to be disabled. Phone manufacturers prefer this model, as it avoids competition with new product lines and avoids the political pitfalls of “dumping” old technologies into “second-class” markets.
Compared with conventional ways of teaching in which students often learn in a passive manner, education using mobile phones enables more active models of learning. For example, participatory sensing (Burke et al., 2006) uses mobile devices to form interactive, participatory sensor networks that enable every user to gather, analyze and share local knowledge.
Unfortunately, we are still far away from reusing smart devices for education purpose due to several problems. First, the power consumption and resource usage of educational applications on mobile platforms has not been explored, so there are no observations indicating that the resource requirement of educational applications can be satisfied by recycled cellular phones. Second, the smart device market is so large that a plethora of different models of cellular phones exist. Handsets could be running diverse operating systems and possess different hardware capabilities. Worse yet, reused handsets may have worn out peripherals or be deployed with intermittent power sources and connectivity. Such extreme heterogeneity is the major challenge of adapting software to different models of devices.
As a pioneering work for designing life-cycle aware mobile devices, we aim at solving the above problems by making connections between the resource provided by mobile devices and demanded by educational applications, and looking into smartphones heterogeneities to propose potential solutions for existing challenges. Specifically, we make the following contributions in this paper: