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Fig. 6.
Activating a new subscription from the OpenIoT platform
this area (i.e. a sensor was not producing data), the QoS Manager will make
decisions with regards to turning on any required new sensor nodes and send
them control messages via the CPSP engine to activate their sensing process.
Mobile data sources will only start producing sensor data after receiving such
instructions. The data is subsequently disseminated to the QoS Manager and
stored in the Cloud Database, as depicted in Fig.
5
.
5 Urban Air Quality Crowdsensing Use Case
To demonstrate the applicability of the CUPUS middleware with quality-driven
data acquisition management, we have developed a mobile crowd-sensing appli-
cation for air quality monitoring. The application integrates the data produced
by low-cost wearable mobile sensors measuring pollutant gas concentrations and
meteorological conditions, such as carbon monoxide, nitrogen dioxide, and sul-
fur dioxide, as well as temperature, relative humidity and atmospheric pres-
sure. A wearable sensor communicates with the mobile device over a Bluetooth
interface.
With our Android mobile application users can define personalized subscrip-
tions to receive alerts regarding air quality in near real-time on their smart-
phones. They can subscribe to receive individual data readings of interest
(e.g., temperature, pressure and SO2 levels) for their current MGRS area, or
to received average data readings in the area. Furthermore, users can define
subscriptions over an arbitrarily selected area. These subscriptions are relayed
through the MB running on user mobile device to the CPSP engine, and further
on to the QoS Manager which is responsible for activation/deactivation of sen-
sor nodes which are currently located in the observed area and can meet user
requirements. Selected sensors are invoked to start periodic readings (as shown in
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