Y. Wang et al.
Keywords Mobile crowdsourced sensing (MCS) · Incentive mechanism ·
Reverse auction · Reputation · Gamification
1 Introduction
Crowdsourcing [1] is a newly emerging service platform and business model in the
Internet. In contrast to outsourcing, where jobs are performed by some designated
workers or companies, with crowdsourcing, jobs are outsourced to a an undefined,
large, anonymous crowd of workers, so-called human cloud, in the form of an open call.
Those jobs can be decomposed into small tasks that are easy for individuals to solve. For
instance, Amazon Mechanical Turk (www.mturk.com) provides on-demand access to
task forces for micro-tasks such as image recognition and language translation, etc.
Nowadays, the proliferation of smartphones provides a new opportunity for extend-
ing existing web-based crowdsourcing applications to a larger contributing crowd,
making contribution easier and omnipresent. Smartphones are programmable and
equipped with a set of cheap but powerful embedded sensors, such as accelerome-
ter, digital compass, gyroscope, GPS, microphone, and camera, etc. These sensors
can collectively monitor a diverse range of human activities and surrounding envi-
ronment. Especially, when a large number of mobile device users are involved in
the sensing procedure, many new applications are enabled by mobile crowdsourced
sensing (MCS).
Mobile crowdsourced sensing applications can be broadly classified into two cate-
gories, personal and community sensing, based on the type of phenomena being mon-
itored [2]. In personal sensing applications, the phenomena pertain to an individual.
For instance, the monitoring of movement patterns (e.g., running, walking, exercis-
ing, etc.) of an individual for personal record-keeping or healthcare reasons. On the
other hand, community sensing pertains to the monitoring of Large-scale phenomena
that cannot easily be measured by a single individual. For example, intelligent trans-
portation systems may require traffic congestion monitoring and air pollution level
monitoring. These phenomena can be measured accurately only when many indi-
viduals provide speed and air quality information from their daily commutes, which
are then aggregated spatio-temporally to determine congestion and pollution levels in
cities.
Community sensing is also popularly called participatory sensing or opportunistic
sensing [3]. In participatory sensing, the participating user is directly involved in
the sensing action e.g., to photograph certain locations or events. In opportunistic
sensing, the user is not aware of active applications, and is not involved in making
decisions instead the smartphone itself makes decisions according to the sensed and
stored data. In brief, MCS is used to refer to a broad range of community-sensing
paradigms.
There exists a great deal of MCS applications in numerous fields, especially in
environmental monitoring and urban sensing (leveraging the sensors in mobile devices
to collecting data from the urban landscape and then make decisions accordingly). For
example, a new mobile crowdsourcing service for improving road safety in cities, was
presented in Aubry et al. [4], which allows users to report traffic offence they witness
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