Image Processing Reference
In-Depth Information
TABLE .
Comparison of Key WSN Standards in Industrial Automation
ZigBee
WirelessHART
ISA.a
Availability
June ,
September ,
Draft
PHY layer
IEEE ..
IEEE ..
IEEE ..
Standard specifies
Layers and
Layers -, and
Layers -, and
Frequency
MHz
. GHz
. GHz
MHz
. GHz
RF transmission
DSSS
FHSS
FHSS
. GHz:
. GHz:
. GHz:
channels
channels
channels
/:
+
channels
Media access
CSMA/CA optional GTS
TDMA, optional CSMA/CA
shared slots within TDMA
slot
TDMA
Network topology
Mesh, star, hybrid
Mesh, star, (hybrid possible,
but not specified)
Mesh, star, hybrid
Bit rate
kbps
kbps
kbps
Security
Optional: symmetric keys,
AES- encryption
Symmetric keys, AES-
encryption
Symmetric keys, AES-
encryption. Optional use of
asymmetric keys
Coexistence
CSMA/CA
Optional channel black
listing, optional CCA,
settable transmission power
levels
Optional channel black channel
assessment (CCA), settable
transmission power levels
Source:
Lennvall, T., Svensson, S., and Hekland, F., in
th IEEE International Workshop on Factory Communication Systems
(WFCS )
, May , , Dresden, Germany. With permission.
27.5.1 Standards Landscape
Table . provides an overview of the three main WSN standards targeting the industrial (pro-
cess) automation market. Most fieldbus organizations refer to either of these standards when they
think about how to integrate WSN into their wired bus infrastructure. In addition, there are pro-
prietary solutions out on the market, which could be considered de facto standards in certain niche
applications.
Below follows some more details on the background of these standards. For a more technical
description of the underlying technologies that are employed, see Section ...
27.5.1.1 ZigBee
One of the best-known standards is the ZigBee standard; a low-power, -cost, and -data rate wire-
less specification, which targets home appliances, toys, industrial applications, building automation,
andthelike.heZigBeestandardisdeveloped,managed,andpromotedbytheZigBeeAlliance[].
hescopeorfocusoftheZigBeeAllianceisondeiningthenetwork,security,andapplicationsot-
ware layers, providing interoperability and conformance testing specifications, and promoting the
ZigBee brand.
27.5.1.2 WirelessHART
WirelessHART is the only industrial WSN standard currently available. It was released during
September [], and is a secure and reliable wireless technology for industrial applications
ranging from class to (see Table .), i.e., from control to process measurement/monitoring. Wire-
lessHART extends the well-known HART standard into the wireless domain, enabling new market
areas for the large number of HART users. HART communication [] is a bidirectional industrial
field communication protocol used to communicate between intelligent field instruments and host
systems. HART is the global standard for smart process instrumentation and the majority, more than
million of smart field devices installed in plants worldwide, are HART-enabled.