further detail the interaction among the many elements composing the
target application;- The Functional Model is used as a reference to the system definition; in
particular it defines Functional Groups such as IoT Services and
Connectivity groups which are fundamental for a correct definition of the
system; - Network connectivity diagrams can be used to plan the connectivity
topology to enable the desired networking capability of the target
application; at the deployment level, the connectivity diagram will be
used to define the hierarchies and the type of the sub-networks
composing the complete system network; - Device Descriptions (such as datasheets and users manuals) can be
used to map actual hardware on the service and resource requirements
of the target system.
First of all, devices in IoT systems include the whole spectrum of technologies
ranging from the simplest of the radiofrequency tags to the most complex
servers. The unifying characteristics are mainly two-fold: on the one hand, every
device is connected with one another forming a part of the IoT; and, on the
other hand, every device is ―smart‖, even though with different degree of
complexity, in that it provides computational capabilities. These two
characteristics are the subject of the first choices a system designer has to
make. Note that, for a given device to be fully interoperable in an IoT-A
compliant system, it must respect the functionality definitions of the Functional
Model. However, legacy systems that do not fully support the FM, may
implement wrappers and adaptation software to comply to the model.
Selecting the computational complexity for a given device is somewhat intrinsic
to the target application. However, choosing among the different connectivity
types is not as straightforward as different choices may provide comparable
advantages, but in different areas. For the same reason, it is possible to realize
different systems implementing the same or similar application from the
functional view, which are extremely different from the Deployment and
Operation view. In this section, we will simply detail the main options for device
connectivity, leaving their impact on the different perspective for Section 5.2.10
in which the design choices for the deployment view are discussed. The
following list provides a few of the typical technologies that can be found in IoT
systems:
Sensor & Actuator Networks; RFIDs and smart tags; WiFi or other unconstrained technologies; Cellular networks.