We introduce a system for sensing complex social systems with data collected from 100 mobile phones over the course of 9 months. We demonstrate the ability to use standard Bluetooth-enabled mobile telephones to measure information access and use in different contexts, recognize social patterns in daily user activity, infer relationships, identify socially significant locations, and model organizational rhythms.

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Reality mining: sensing complex social systems

Sensor networks with battery-powered nodes can seldom simultaneously meet the design goals of lifetime, cost, sensing reliability and sensing and transmission coverage. Energy-harvesting, converting ambient energy to electrical energy, has emerged as an alternative to power sensor nodes. By exploiting recharge opportunities and tuning performance parameters based on current and expected energy levels, energy harvesting sensor nodes have the potential to address the conflicting design goals of lifetime and performance. This paper surveys various aspects of energy harvesting sensor systems- architecture, energy sources and storage technologies and examples of harvesting-based nodes and applications. The study also discusses the implications of recharge opportunities on sensor node operation and design of sensor network solutions.

Energy Harvesting Sensor Nodes: Survey and Implications

"Gamification" is an informal umbrella term for the use of video game elements in non-gaming systems to improve user experience (UX) and user engagement. The recent introduction of 'gamified' applications to large audiences promises new additions to the existing rich and diverse research on the heuristics, design patterns and dynamics of games and the positive UX they provide. However, what is lacking for a next step forward is the integration of this precise diversity of research endeavors. Therefore, this workshop brings together practitioners and researchers to develop a shared understanding of existing approaches and findings around the gamification of information systems, and identify key synergies, opportunities, and questions for future research.

http://gamification-research.org/wp-content/uploads/2011/04/01-Deterding-Sicart-Nacke-OHara-Dixon.pdf

Gamification. using game-design elements in non-gaming contexts

Wireless power technology offers the promise of cutting the last cord, allowing users to seamlessly recharge mobile devices as easily as data are transmitted through the air. Initial work on the use of magnetically coupled resonators for this purpose has shown promising results. We present new analysis that yields critical insight into the design of practical systems, including the introduction of key figures of merit that can be used to compare systems with vastly different geometries and operating conditions. A circuit model is presented along with a derivation of key system concepts, such as frequency splitting, the maximum operating distance (critical coupling), and the behavior of the system as it becomes undercoupled. This theoretical model is validated against measured data and shows an excellent average coefficient of determination of 0.9875. An adaptive frequency tuning technique is demonstrated, which compensates for efficiency variations encountered when the transmitter-to-receiver distance and/or orientation are varied. The method demonstrated in this paper allows a fixed-load receiver to be moved to nearly any position and/or orientation within the range of the transmitter and still achieve a near-constant efficiency of over 70% for a range of 0-70 cm.

/pdf/analysis-experimental-results-and-range-adaptation-of-2xhdldcpe3.pdf

Analysis, Experimental Results, and Range Adaptation of Magnetically Coupled Resonators for Wireless Power Transfer

Recently, indoor positioning systems (IPSs) have been designed to provide location information of persons and devices. The position information enables location-based protocols for user applications. Personal networks (PNs) are designed to meet the users' needs and interconnect users' devices equipped with different communications technologies in various places to form one network. Location-aware services need to be developed in PNs to offer flexible and adaptive personal services and improve the quality of lives. This paper gives a comprehensive survey of numerous IPSs, which include both commercial products and research-oriented solutions. Evaluation criteria are proposed for assessing these systems, namely security and privacy, cost, performance, robustness, complexity, user preferences, commercial availability, and limitations.We compare the existing IPSs and outline the trade-offs among these systems from the viewpoint of a user in a PN.

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A survey of indoor positioning systems for wireless personal networks

Location awareness is an important capability for mobile computing. Yet inexpensive, pervasive positioning—a requirement for wide-scale adoption of location-aware computing—has been elusive. We demonstrate a radio beacon-based approach to location, called Place Lab, that can overcome the lack of ubiquity and high-cost found in existing location sensing approaches. Using Place Lab, commodity laptops, PDAs and cell phones estimate their position by listening for the cell IDs of fixed radio beacons, such as wireless access points, and referencing the beacons' positions in a cached database. We present experimental results showing that 802.11 and GSM beacons are sufficiently pervasive in the greater Seattle area to achieve 20-30 meter median accuracy with nearly 100% coverage measured by availability in people's daily lives.

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Place lab: device positioning using radio beacons in the wild

This paper presents the wireless identification and sensing platform (WISP), which is a programmable battery-free sensing and computational platform designed to explore sensor-enhanced radio frequency identification (RFID) applications. WISP uses a 16-bit ultralow-power microcontroller to perform sensing and computation while exclusively operating from harvested RF energy. Sensors that have successfully been integrated into the WISP platform to date include temperature, ambient light, rectified voltage, and orientation. The microcontroller encodes measurements into an electronic product code (EPC) Class 1 Generation 1 compliant ID and dynamically computes the required 16-bit cyclical redundancy checking (CRC). Finally, WISP emulates the EPC protocol to communicate the ID to the RFID reader. To the authors' knowledge, WISP is the first fully programmable computing platform that can operate using power transmitted from a long-range (UHF) RFID reader and communicate arbitrary multibit data in a single response packet.

http://www.alansonsample.com/publications/docs/2008%20-%20TIM%20-%20Design%20RFID%20Based%20Battery%20Free%20Programmable%20Sensing%20Platform.pdf

Design of an RFID-Based Battery-Free Programmable Sensing Platform

Advances in location-enhanced technology are making it easier for us to be located by others. These new technologies present a difficult privacy tradeoff, as disclosing one's location to another person or service could be risky, yet valuable. To explore whether and what users are willing to disclose about their location to social relations, we conducted a three-phased formative study. Our results show that the most important factors were who was requesting, why the requester wanted the participant's location, and what level of detail would be most useful to the requester. After determining these, participants were typically willing to disclose either the most useful detail or nothing about their location. From our findings, we reflect on the decision process for location disclosure. With these results, we hope to influence the design of future location-enhanced applications and services.

/pdf/location-disclosure-to-social-relations-why-when-what-people-4f7zl7wmw4.pdf

Location disclosure to social relations: why, when, & what people want to share

We present WISP, a wireless, battery-free platform for sensing and computation that is powered and read by a standards compliant Ultra-High Frequency (UHF) RFID reader. To the reader, the WISP appears to be an ordinary RFID tag. The WISP platform includes a general-purpose programmable flash microcontroller and implements the bi-directional communication primitives required by the Electronic Product Code (EPC) RFID standard, which allows it to communicate arbitrary sensor data via an EPC RFID reader by dynamically changing the ID it presents to the reader. For each 64 bit “packet,” the WISP's microcontroller dynamically computes the 16-bit CRC that the EPC standard requires of valid packets. Because the WISP device can control all bits of the presented ID, 64 bits of sensor data can be communicated with a single RFID read event. As an example of the system in operation, we present 13 hours of continuous-valued light-level data measured by the device. All the measurements were made using power harvested from the RFID reader. No battery, and no wired connections (for either power or data) were used. As far as we are aware, this paper reports the first fully programmable computing platform that can operate using power transmitted from a long-range (UHF) RFID reader and communicate arbitrary, multi-bit data in response to a single RFID reader poll event.

A wirelessly-powered platform for sensing and computation

This paper presents a wireless, battery-free, platform for sensing and computation that is powered and read by a standards compliant ultra-high frequency (UHF) radio frequency identification (RFID) reader. The WISP (wireless identification and sensing platform) includes a fully-programmable 16 bit microcontroller with analog-to-digital converter. The microcontroller firmware implements portions of the electronic product code (EPC) class 1 generation 1 protocol. When queried, the platform communicates arbitrary sensor data by emulating an EPC tag whose ID encodes the desired sensor data; the required 16-bit CRC is computed dynamically by the microcontroller. The RFID reader reports the received tag ID to application software which can interpret the information contained in the tag ID. The programmability of the WISP along with its implementation as a PCB allows for flexible integration of arbitrary low-power sensors. Furthermore, sensors are also exclusively powered from the RFID reader resulting in a completely battery free device. Sensors integrated into the WISP platform so far include light, temperature, and rectified voltage, and are shown experimentally to have an operating range of up to 4.5m. To the authors' knowledge, WISP is the first fully programmable computing platform that can operate using power transmitted from a long-range (UHF) RFID reader and communicate arbitrary, multi-bit data in a single response packet.

Pauline Powledge

Papers

Place lab: device positioning using radio beacons in the wild

Design of an RFID-Based Battery-Free Programmable Sensing Platform

Location disclosure to social relations: why, when, & what people want to share

A wirelessly-powered platform for sensing and computation

Design of a Passively-Powered, Programmable Sensing Platform for UHF RFID Systems