Can Wireless Standards Work Together?April 1, 2006 By: Dr. Peter Fuhr, Oak Ridge National Laboratory, Hesh Kagan, Invensys Process Systems Sensors
The industrial world has spawned numerous standards bodies. Can they bridge the chasms between IT, RF, and wireless industrial bus protocols with standards that deliver coexistence and interoperability?
The introduction of wireless data transport into the industrial sector represents a convergence of the monitoring and control world, wireless sensor technology, and the IT community. Each element of this triad has its own standards and practices. The challenge for those currently using wireless technology, as well as those contemplating future deployments, is to unravel the tangled web of the technologies, standards, and operating principles.
In the wireless world, the Institute of Electrical and Electronic Engineers (IEEE) plays a crucial technical role in developing standards upon which wireless solutions can be based. The IEEE has delineated coverage zones for wireless personal area networks (WPANs), wireless local area networks (WLANs), wireless metropolitan area networks (WMANs), and wireless wide area networks (WWANs). Variants arise in each sector when increasing mobility and data-rate demands are factored into the application base. Technologies developed for a particular size network can cross into another. Topological differences, typically in terms of network design and deployment, lead to even more variations. In addition, existing wireless services, such as pagers and cellular telephony, must be accounted for, leading to significant concerns regarding the coexistence and interoperability of deployed systems.
Figure 1. An overview of the IEEE 802.xx wireless standards shows a wide range of functionality and capability
The most prominent IEEE standards for wireless data communications fall within the 802.xxx IEEE numbering system. The IEEE 802.11 wireless standards specify an over-the-air interface between a client and a base station or access point, as well as among wireless clients. These standards are comparable to the IEEE 802.3 standard for wired Ethernet LANs. The IEEE 802.11 specifications address both the physical (PHY) and media access control (MAC) layers and are tailored to resolve compatibility issues among manufacturers of wireless LAN equipment.
The IEEE 802.15 Working Group provides standards for low-complexity and low-power wireless connectivity. Today, there are four IEEE 802.15 standards projects in development:
- 1. IEEE Std 802.15.1-2002—1 Mbps WPAN/Bluetooth v1.x derivative work
- 2. P802.15.2—Recommended Practice for Coexistence in Unlicensed Bands
- 3. P802.15.3—20+ Mbps High Rate WPAN for Multimedia and Digital Imaging
- 4. P802.15.3a—110+ Mbps Higher Rate Alternative PHY for 802.15.3
- 5. P802.15.4—200 Kbps maximum for interactive toys, sensors, and automation needs
The IEEE 802.16 specifications support the development of fixed, broadband wireless access systems to enable rapid worldwide deployment of innovative, cost-effective, and interoperable multivendor broadband wireless access products.
In an attempt to achieve functionality across different types of networks, IEEE committees have been working for years to identify key logical elements in the delivery of data. Some of these elements reside in the description and specification of the physical channel; others reside in the control of that channel (e.g., the medium access control layer). In addition, it's frequently necessary to bridge between the two delivery methods, such as when you plug your CAT5 wire into your 802.11 router. The 802 specifications are meant to define how such interoperability can effectively perform. An overview of the 802.xx standards is shown in Figure 1.
Promoters and Supports
Trade groups have been formed to support each of these standards, or at least pieces of the standards. For example, the Wireless Fidelity (WiFi) Alliance is the trade organization affiliated with the IEEE 802.11 standard. The WiFi Alliance—a global, nonprofit industry trade association with more than 200 member companies—is devoted to promoting the growth of WLANs. The alliance's certification programs ensure the interoperability of WLAN products from different manufacturers, with the objective of enhancing the wireless user experience. Since March 2000, more than 2000 products have been WiFi certified, encouraging the use of WiFi across consumer and enterprise markets.
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