The OpenIoT Approach to Sensor Mobility with Quality-Driven Data Acquisition Management - Interoperability and Open-Source Solutions for the Internet of Things - page 51

2. Energy eciency management: Effectively manage the energy/battery
consumption of sensors/mobile devices in order to maximize battery lifetime
and minimize energy consumption while maintaining a required level of data
quality (in terms of frequency and accuracy of sensor readings within a certain
geographical area).

The QoS Manager has to administrate the sensing process from various data
sources in the system. For that purpose, it needs to monitor both subscriptions
and publications received by the CPSP Engine. The QoS Manager maps active
subscriptions and valid publications to geographical areas and also publishes
processed readings (e.g., average sensor readings for particular areas if requested
by users) through the CPSP Engine. Additionally, the QoS broker sends con-
trol messages to the CUPUS middleware based on the QoS Manager decisions.
This way, the CPSP engine can turn them on/off when needed by forwarding
subscriptions/unsubscriptions received from the QoS broker to them. The QoS
Manager stores all received publications and subscriptions during their validity
periods in memory for later use in the QoS logic component. To limit the amount
of memory used for QoS Manager operation in practice, we limit the time win-
dow for publication storage to 30 min and calculate average sensor readings also
for this time window.
The QoS Manager is responsible for three key functionalities: (1) QoS subscrip-
tion monitoring and management, whereby the QoS Manager aggregates CUPUS
subscriptions and determines global application requirements with respect to sen-
sor data acquisition from mobile sources which are integrated through the CUPUS
middleware; (2) QoS publication monitoring and management, whereby the QoS
Manager aggregates monitored sensor data publications, and manages the sensor
data acquisition in order to optimize energy and bandwidth consumption while
meeting application requirements and (3) providing sensor data readings to
the rest of the OpenIoT platform, as explained in Sect. 4 . Based on reported mobile
ICO battery levels, the QoS Manager decides about activation/deactivation of
available data sources.
The QoS Manager web interface

Q w offers services for components requiring
the request-reply interaction mechanism. It is used to retrieve active mobile
ICOs within an area, provide average sensor readings for an area, or define a
subscription over an area of interest. The data matching such subscription is
stored in the OpenIoT Data Cloud for later usage.

3 Interactions Within the CUPUS Middleware

In this section we provide a detailed description of interactions between CUPUS
components (the Q p interface).

Connect and disconnect. The two methods are used by subscribers, publishers
and MBs. The method connect adds subscriber/publisher/MB identifier into the
list of connected components maintained by the CPSP engine, while the method
disconnect removes them from the list. In case a subscriber or MB reconnect