wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

51-2 Industrial Communication Systems
51.2.1 IP as Open Standard Protocol Instead of Proprietary Protocols
On low-power wireless devices like WSN nodes and for smart and cooperating objects (SCO), Zigbee
over IEEE 802.15.4 is the predominating protocol today. Alternatively, for machine-to-machine communication
(M2M) and for integration purposes in enterprise systems, IP would be a suitable contributor.
Until recently, IP was not an option because there were no IP stacks available, which would run on
resource-constrained WSN nodes. However, today resource optimized IP stacks are available which run
on tiny 8 bit microcontrollers like TI’s MSP 430—a commonly used microcontroller in WSN. The footprint
of such IP stacks for microcontrollers is around 12.k byte (cf. uIPv6 [Dur08]).
51.2.2 IP Routers Instead of Complex Gateways
WSN lie on the edge of networks or at the field level in process automation. Today, specific gateway or
proxy concepts are used to integrate WSN with their proprietary protocols into enterprise systems or
higher value services in IP-based networks. Changes in protocol data representation and data encoding
require high efforts on the necessary application layer (APL) gateways. In contrast to gateways, routers
just forward packets and do not need to have a deep knowledge about the mission of the specific WSN
and applied protocols.
51.2.3 Use of Already Existing Protocols, Tools, and Applications
Hooked on IP, other higher level protocols, tools, and applications have been established. Protocols like
DNS, DHCP, Zeroconf, etc., can be used for naming, addressing, discovery, and configuration. Tools
like SNMP, ping, arp, traceroute, etc., are usable for management purposes. Even on APL, matured protocols,
data models, and services, such as HTTP, HTML, XML, SOAP, REST, etc., are well established
and fundamental for important IT developments.
51.2.4 New Architectural Styles like Service-Oriented Architectures
New methodologies and paradigms like service-oriented architectures (SOA) would benefit from
IP-based communication [Boh09]. Software and service industry uses Web services as glue between
different applications for integration and interoperability. WSN are integrated in networking environments
by using Web services via complex APL gateways. But this is not a good solution on a long term.
In future applications, new concepts and architectures are possible and much research is necessary to
find acceptable solutions for service orientation in WSN. Challenges are, e.g., to find acceptable compression
for XML data representation, to specify Web service-compliant profiles (similar to the devices
profile for Web services—DPWS—for WSN), to realize cost-effective SOA solutions, and to reduce
energy consumption for service-oriented solutions for WSN [Mor09,Mor09_2].
51.2.5 IP Support in Operating Systems
Today, IP is supported by all classes of operating systems ranging from desktop operating systems,
embedded and real-time operating systems, to operating systems for WSN like Contiki [Dun04]. IP
protocol stacks are available as an integral part of the operating system, as open-source software stacks
and commercial solutions. The uIPv6 [Dun07,Dur08] stack is an implementation of the 6LoWPAN
protocols described in this section. For proprietary protocols, there are only a few open-source solutions
available. They are limited to specific application areas and application niches. Future networks of SCO
are not for niche market only. They will pave the way for very new and broad application areas. So, IP
radically helps to enforce that development.
© 2011 by Taylor and Francis Group, LLC