Digital Signal Processing Reference
In-Depth Information
Localization
: A sensor value is naturally associated with a certain area. However,
random deployment and mobility prevent concluding the location information
from source node identifiers, which necessitates either online (distributed) or
offline (centralized) localization services.
Time synchronization
: Several WSN applications, such as event alerts and
tracking, require exact timestamping of sensor events to compare the order of
events. As low cost sensor nodes do not have accurate time source, an agreement
on global time is achieved with time synchronization service.
A WSN provides at least the sensing, data processing, and data transfer services.
The localization and time synchronization services are not usually considered in
proposed WSN standards but need customized solutions.
2
Key Standards and Industry Specifications
In the sensor industry, a vast number of sensors exists to measure physical
parameters, such as temperature, pressure, humidity, illumination, gas, flow rate,
strain, and acidity. Standardized sensor interfaces, data formats, and communication
protocols are required to enable effective integration, access, fusion, and the use of
sensor-derived data. The goal is to allow sensors from different manufacturers to
work together without human intervention and customization.
2.1
IEEE 1451
IEEE 1451 standard family defines a set of open, network-independent commu-
nication interfaces for connecting transducers (sensors and actuators) to micro-
processors, instrumentation systems and networks. In IEEE 1451, a single sensor,
an actuator, or a module comprising several transducers and any data conversion
or signal conditioning (e.g. signal amplification or filtering) is referred to as
Transducer Interface Module (TIM). Transducer Electronic Data Sheet (TEDS)
describes a TIM and defines a set of commands to control and read data from
the TIM. TEDS virtually eliminates error prone, manual entering of data and
system configuration and allows transducers to be installed, upgraded, replaced
or moved with plug-and-play principle. IEEE 1451 provides interfaces for several
standardized communication protocols by IEEE 1451.2 through IEEE 1451.6.
IEEE 1451.2 defines wired point-to-point communication. IEEE 1451.3 defines
distributed multi-drop system, where a large number of TIMs may be connected
along a wired multi-drop bus. IEEE 1451.4 specifies mixed-mode communication
protocols, which carry analog sensor values with digital TEDS data. IEEE 1451.6
defines a high-speed Controller Area Network (CAN) bus. IEEE 1451.5 standard
