ACM Symposium on Computing and Development 

Abstract: We endow the mobile phone with a low-cost, open interface that can parasitically power external peripherals, and transfer data to and from them, using analog, digital, and serial signaling, using only the existing headset audio port. This interface, called HiJack, allows the mobile phone to easily integrate with a range of external sensors, opening the door to new phone-centric sensing applications. In this paper, we characterize the signaling and power delivery capability of the audio jack, design circuits and software to transfer data and harvest energy, and evaluate the performance of our designs. We also use the mobile phone's audio channel to create a layered communications stack that supports low-level, analog signaling and high-level, multiplexed data communications with external devices. Our design supports a single, bi-directional communications channel at a data rate of 8.82 kbps over a Manchester-encoded serial stream, using just a few discrete components and the hardware peripherals found in almost any microcontroller. Our harvester delivers 7.4 mW to a load with 47% efficiency using components that cost $2.34 in 10K volume. Integrating the pieces, we present a combined system for delivering data and power over audio, and demonstrate its use by turning an iPhone into an inexpensive oscilloscope.

Abstract: Broadband penetration is increasing in South Africa, particularly on mobile devices, but little is known about the performance of fixed or mobile broadband in the country. This lack of empirical data imposes significant limitations to innovation, because broadband performance metrics help users audit their connectivity costs and regulators to make informed decisions about policies and infrastructure investments. We present the results from a measurement study of both fixed and mobile broadband connections in South Africa. We use measurement software that we implemented on mobile phones and home routers and adapted to address challenges that are unique to the developing world. Our findings suggest that consumers in South Africa are not getting advertised speeds, that mobile broadband generally has higher throughput than fixed broadband, and that interconnection between ISPs (or lack thereof) plays a significant role in determining the reliability and performance that users ultimately receive. Often, high latencies to destinations introduce significant performance bottlenecks, suggesting that, in addition to investments in higher throughput links, effort should be devoted to improving interconnection between ISPs and locating content closer to users. Our study, along with our open source technical platform, embodies an archetypal method for monitoring broadband performance in developing countries.

Abstract: Textbooks play an important role in any educational system. Unfortunately, many textbooks produced in developing countries are not written well and they often lack adequate coverage of important concepts. We propose a technological solution to address this problem based on enriching textbooks with authoritative web content. We augment textbooks at the section level for key concepts discussed in the section. We use ideas from data mining for identifying the concepts that need augmentation as well as to determine the links to the authoritative content that should be used for augmentation. Our evaluation, employing textbooks from India, shows that we are able to enrich textbooks on different subjects and across different grades with high quality augmentations using automated techniques.

Abstract: Due to the rapid spread of mobile phones and coverage in the developing world, mobile phones are being increasingly used as a technology platform for developing-world applications including data collection. In order to reach the vast majority of mobile phone users without access to specialized software, applications must make use of interactive voice response (IVR) UIs. However, it is unclear whether rural users in the developing world can use such UIs without prior training or IVR experience; and if so, what UI design choices improve usability for these target populations.This paper presents the results of a real-world deployment of an IVR application for collecting feedback from teachers in rural Uganda. Automated IVR data collection calls were delivered to over 150 teachers over a period of several months. Modifications were made to the IVR interface throughout the study period in response to user interviews and recorded transcripts of survey calls. Significant differences in task success rate were observed for different interface designs (from 0% to over 75% success). Notably, most participants were not able to use a touchtone or touchtone-voice hybrid interface without prior training. A set of design recommendations is proposed based on the performance of several tested interface designs.