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We present MoodScope, a software system which infers the mood of its user based on how the smartphone is used. Similar to smartphone sensors that measure acceleration, light, and other physical properties, MoodScope is a "sensor" that measures the mental state of the user and provides mood as an important input to context-aware computing. We run a formative(More)
System power models are important for power management and optimization on smartphones. However, existing approaches for power modeling have several limitations. Some require external power meters, which is not convenient for people to use. Other approaches either rely on the battery current sensing capability, which is not available on many smartphones, or(More)
Social networks are the most engaging applications on mobile devices, and they are becoming the main sources for users to consume content. However, content retrieval, especially for embedded links and multimedia, can often be too slow, too energy hungry or too expensive for on-the-go mobile users. To address these issues, we collect and analyze a large set(More)
Wi-Fi tethering (i.e., sharing the Internet connection of a mobile phone via its Wi-Fi interface) is a useful functionality and is widely supported on commercial smartphones. Yet existing Wi-Fi tethering schemes consume excessive power: they keep the Wi-Fi interface in a high power state regardless if there is ongoing traffic or not. In this paper we(More)
Email is a key application used on smartphones. Even when the phone is in stand-by mode, users expect the phone to continue syncing with an email server to receive new mes-sages. Each such sync operation wakes up the smartphone for data reception and processing. In this paper, we show that this "cost of email sync" in stand-by mode constitutes a significant(More)
In this paper, we present Structon, a novel approach that uses Web mining together with inference and IP traceroute to geolocate IP addresses with significantly better accuracy than existing automated approaches. Structon is composed of three ideas which we realize in three corresponding steps. First, we extract geolocation information of Web server IP(More)
The contradiction between dynamic user traffic and fixed data plans has drawn increasing attention in the field of mobile applications. In this paper we build a data plan sharing system named INDAPSON to consider a scenario where some smartphone users have surplus data traffic and are willing to help others download data. Virtual credits can be gained as(More)
In this paper, we present the challenges in supporting multimedia, in particular, VoIP services over multihop wireless networks using commercial IEEE 802.11 MAC DCF hardware, and propose a novel software solution, called Layer 2.5 SoftMAC. Our proposed SoftMAC resides between the IEEE 802.11 MAC layer and the IP layer to coordinate the real-time (RT)(More)
Loaded with personal data, e.g. photos, contacts, and call history, mobile phones are truly personal devices. Yet it is often necessary or desirable to share our phones with others. This is especially true as mobile phones are integrating features conventionally provided by other dedicated devices, from MP3 players to games consoles. Unfortunately, when we(More)