Hybrid Systems

It's no surprise that the proliferation of electronics continues to redefine work and play. Local area networks (LANs), which have long performed as distribution workhorses, are rapidly evolving with the breakneck pace of wireless (WLAN). As Kourosh Parsa, a senior wireless systems engineer with

Ortronics/Legrand put it, “We are experiencing a global wireless ‘gold rush.’”

The introduction of next-generation wireless technologies and the expansion of 802.11 WLAN systems are driving demand for a domain that still relies very heavily on wired infrastructure. Not too long ago, convention suggested that computer networks for the home and business could be developed from either wired or wireless technology. Both technologies can claim advantages over the other. Both rep-resent viable options for residential, commercial and industrial LANs, but they needn’t compete against each other anymore. Nobody expects one size to fit all. Coexistence is the new norm.

Product developments and manufacturer alliances continue to provide proof that neither a wire nor air interface will emerge as the single solution to deploy next-generation applications and platforms. Rather, there is a growing realization that the seamless integration of hybrid systems is the ticket to the future, and electrical contractors are in the driver’s seat.

“If anything, there is a single-mindedness among industry leaders to adopt hybrid solutions—that is, wireless and wired solu-tions combined together in a single system,” said Kurt Scherf, vice president and principal analyst at Parks Associates, a Dallas-based market research firm. Scherf and others agree that it is not wise to box yourself in by thinking there’s only one solution to the exclusion of the others. In nearly every segment of systems work, there are a variety of hybrid capabilities to build future network configurations.

It’s all hybrid, all opportunity

According to David Veneski, Fluke Networks marketing manager for certification products, the common perception of a wireless net-work is tied directly to the visibility of the final link. Although users are not tethered, the wireless access points that transmit to those end-users are connected to the network through a structured wiring system.

“Some installers are worried that wireless will destroy their cable installation business. They should remember that there is no such thing as a purely wireless network. All the wireless access points need data cabling, electrical cabling or possibly the new combina-tion of Power over Ethernet [PoE]. This is an opportunity, not a threat,” Veneski said.

PoE is a relatively new addition to the cabling market that can pull double duty to provide both data and electrical power. The dual functionality, Veneski pointed out, results in a simplified installation—fewer wires to pull—but requires added knowledge on the part of the cable installer.

The use of structured wiring as a backbone for home automation and networking applications is increasing, especially in new home construction.

“We anticipate that hybrid solutions will make up 60 percent or more of the home networking products—data, voice and multime-dia—that are shipped by the end of 2008,” Sherf said.

Building automation and industrial controls incorporate similar infrastructure. In the vast majority of wireless networks deployed today—also known as 802.11 in IEEE Wireless Local Area Network (WLAN) standards, wireless is the means of connecting end-users to the wired 802.3 Ethernet LAN where network resources reside.

Wireless is the access method, but the core and backbone of the network still is wired. “All networks have wires, even wireless networks. In order for the access points to deliver performance the users expect, they must be connected by cabling that meets the design specifications for that network,” Veneski said.

In hybrid systems, wireless access points and hardwired resources, such as coaxial, structured wiring and fiber, are teaming up to provide data and communications networks, sensors and controls, security systems and energy management systems. But don’t let the semantics of the term “hybrid systems” create confusion.

In your region, the deployment may be known as “wired-wireless integration,” “converged network” or a “wireless overlay,” accord-ing to Wiring.com Inc.’s John Colodny.

“Typically, it’s putting in Cat 5e or Cat 6 wiring to the faceplates and putting a separate wireless infrastructure into the same space. We find that 99 percent of the time wireless is being installed to support a specific application. Wireless is not a replacement yet; instead, it’s an en-hanced capability,” Colodny said.

Regardless of the nomenclature, a centralized wired network architecture is required for the wireless system to operate. It’s the suc-cessful foundation for adding wireless in retrofit situations in homes and historical structures where opening walls for additional wir-ing can be intrusive.

Partnerships expand functionality

Although a conventional hybrid system teams wired and wireless components, there are recent examples of hybrid partnerships between data cabling and wireless access point manufacturers that can offer a comprehensive infrastructure solution.

In the past year, Ortronics/Legrand introduced the Wi-Jack Duo, a small dual band/dual radio access point that fits into a standard wall box in the footprint of a standard faceplate and extends 12 mm from the wall. The device supports 802.11 a/b/g operation, allowing simul-taneous operation at 2.4 and 5 GHz at speeds up to 54 Mb/s, and can be used with a dedicated air monitor.

“By bringing the access point into the wall outlet, we have more closely integrated the WLAN into the existing structured cabling in-frastructure,” Parsa said.

Scherf said that even service providers are pushing home networking to extend the value and utility of hybrid-based services.

“Take, for example, the deployment efforts of both AT&T and Verizon to deliver deep-fiber-based broadband and television services to the home. As they are installing these services, they’re using residential gateways that have both a wireless (802.11g) and a coax/twisted pair solution to distribute TV content, broadband, communications, etc. They definitely see the value in having the wireless component, since it provides a homeowner with much greater flexibility of where to use a laptop computer or locating a desktop PC that may not be near a coax, Ethernet or phone outlet,” Scherf said.

The ZigBee Alliance is an organization of approximately 250 companies working on standardization and common interoperability plat-forms for wireless devices. Based on IEEE 802.15.4, with the goal of creating a global standard for sensor and control networks, ZigBee also has a stake in hybrid compatibility.

“ZigBee knows how to talk to 802.11, which knows how to talk to Ethernet, which knows how to talk to the Internet. By design, all these platforms are part of the broader standards solution and should be capable of working together,” said ZigBee chairman, Bob Heile.

One of ZigBee’s initiatives is to collaborate on the interoperability of protocols for back office functions in building control systems. “One of the solutions on the wired side is BACnet. We’re working with ASHRAE and the BACnet standards group to create joint common solutions that not only allow communication on both sides of the network, but allow applications to be shared and to create a seamless user-friendly experience,” Heile said.

Testing wired and wireless traffic

One of the primary reasons for WLAN’s popularity is its host of mobility applications, and the next generation of 802.11n devices promise sufficient throughput for many business users. But it’s not for everyone. WLAN can be susceptible to interference and service attacks. In-dustry experts, such as Eric Anderson, Fluke Network’s product manager for portable network analysis, predict that new, more complex applications are expected to require even greater bandwidth than even 802.11n can provide.

“WLANs generally have more latency and jitter, which impact VoIP and live video applications. Security is a much bigger concern with WLANs. So in industrial and commercial environments, IT managers employ a hybrid approach, using WLAN where it’s applicable and wired where it’s best suited,” Anderson said.

Hybrid technologies are placing new challenges on technicians who must increasingly troubleshoot mixed network environments, which up to now required different tools and different techniques. According to Anderson, wired and wireless networks have both passive and ac-tive components. Within wired networks, the passive components typically include the twisted-pair cabling, RJ-45 jacks, patch cables, optical fiber cabling, fiber connectors and patch panels. The certification of the passive wired infrastructure is a mature-use model, and best prac-tices, standards and instrumentation are available for certifying wires.

“But certification of active 802.3 wired LANs is not a common practice. Wireless is even less mature. There is no industry-recognized best practice for certifying the ‘passive’ component of the WLAN or the RF environment. And there’s no best practice for certification of the active 802.11 wireless LAN,” Anderson said.

Seeing the future through optics

Telecommunications researchers the Georgia Institute of Technology have demonstrated a novel communications network design that would provide both ultra-high-speed wireless and wired access services from the same signals carried on a single optical fiber.

The new hybrid system could allow dual wired/wireless transmission of the same content, such as high-definition television, data and voice up to 100 times faster than current networks. The new architecture is projected to reduce the cost of providing dramatically improved service to conference centers, airports, hotels, shopping malls and, ultimately, to homes and small offices.

The optical-wireless access network envisioned by Gee-Kung Chang, an electrical and computer engineering professor and his colleagues would connect to existing optical fiber networks located throughout the country. Using a technique developed at Georgia Tech, wireless and baseband signals carried by multiple wavelengths would be converted onto the millimeter-wave carrier simultaneously.

“If you look into the future, the broadest bandwidth possible would come through combining and integrating optical and wireless serv-ices in a single network,” Chang said.

Added Fluke Network’s Anderson, “If a contractor wants to grow his business, he should learn more about WLAN technology. Net-works will increasingly become hybrid, and knowledge of both wired and wireless network deployment and testing will become more important in the future.

MCCLUNG, owner of Woodland Communications, is a construction writer from Iowa. She can be reached via e-mail at mcclung@lisco.com.


About the Author

Debbie McClung

Freelance Writer
Debbie McClung, owner of Woodland Communications, is a construction writer from Iowa.

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