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Wireless: Generation Next continued

Mesh Networks: The Next Step?

What the ZigBee Alliance brings to the table for wireless building controls is its focus on being able to use IEEE’s standard not only within a hub (point-to-point) network, but also in a mesh network. In a mesh network, each device (or point) in the wireless network can communicate with each other, as opposed to a hub network, where each point can only communicate with the “master” device. Therefore, if a point within the network fails, the signal can continue to move toward its destination by finding another point in the network through which to travel.

Mesh networking, which has its origins in the military, is being considered as a solution to a problem that faces all types of wireless technology applications—interference. When the numerous radio signals traveling throughout a wireless network vie for airspace, they can collide, and as a result, none make it to their destination. Structural elements of a building and items inside can also stop signals in their tracks.

“For control applications, mesh networking is the best choice,” says Ehrlich. “It offers a solution that is much more robust, has a lower cost, and has longer battery life than a hub based system.”

Shukla sees mesh technology as a way for wireless to succeed in the controls market. “There is no doubt that mesh network architecture has been predominantly adopted in a number of application scenarios compared to hub networks,” he says. “This is owing to benefits such as the self-forming and self-healing capabilities of mesh. With wireless networks, reliability is probably one of the biggest issues to be addressed to gain widespread acceptance, and wireless mesh networks have been able to provide this reliability.”

Ehrlich says, “I expect mesh technology to follow the curve of most new technologies. For the next few years, it will be used on a small percentage of projects. As it proves out, and the standards are completed, it will be used more often.”

But Will It Work... Securely?

In terms of reliability, Ehrlich says that for the facility managers he consults with about wireless control systems, this is a top concern. “The first worry is if the technology really works,” he says. “Many have a wait and see attitude. There is no question it will work. The question is how long it will take for facility professionals to be comfortable with it.”

Early adopters of the technology are key to demonstrating proven operating efficiencies, no matter what the application. “Currently, about 3% of facilities are using wireless clock systems,” says Michael Garven, director of sales for BRG Precision Products based in Derby, KS. “So, there are [facility managers in] the other 97% who need to be educated about wireless systems.” BRG manufactures and installs synchronized, wireless clock systems for commercial and industrial facilities.

Garven adds, “Wireless systems can not only save money up front when building a facility, but will also reduce long-term maintenance as compared to a hard wired system.”

As with wired systems that transport information, data security is of paramount importance. Many facility managers are concerned about system vulnerabilities that may enable hackers to disrupt operations or acquire information about the organization.

Lester LaPierre, marketing manager at Schlage/Ingersoll Rand Security Technologies in West Chicago, IL, notes that spread spectrum technology addresses the issue of hackers. Developed by the U.S. military for secure communications, this technology was declassified in 1985 for commercial use.

“There are two kinds of spread spectrum technology—frequency hopping and direct sequence,” says LaPierre. “We use direct sequence. In this scenario, there is a center frequency, and the system transmits on dozens of frequencies above and below the center frequency.”

LaPierre explains how the spread spectrum technology combats unauthorized access data transmitted through the system. “Say, for example, you have a 26-bit Wiegand prox card, and you present that to a lock. The system takes that card data in binary form (adding ones and zeros), and the data is spread around dozens of frequencies. That spreading algorithm is how the signal is encoded. If someone were trying to intercept with high-tech equipment, like a spectrum analyzer, perhaps they could discover what the center frequency is. However, the ones and zeros that are added, along with the bits that the system adds, makes it more difficult. All the information is also buried in a noise field, so someone cannot make out the hard edges that represent a one or a zero. Even if they could, they wouldn’t know what the spreading algorithm is.”

Facility managers should be sure to find out from potential vendors what security safety nets are built into their respective systems.

A Practical Approach

Along with the increasing flexibility of wireless building management systems come more choices to consider. It can be confusing for a facility professional who wants to glean the best fit for his or her situation. And certainly, one size does not fit all.

Says Williamson, “It comes down to how practical the wireless solution is for a given application (i.e. HVAC, security, or lighting). If a wireless solution effectively solves whatever challenges a building owner is facing in a given situation, then that is the approach to use. ”

Whether a facility manager is looking to jump on the fast track from no automation to wireless, or wants to add wireless into an existing wired infrastructure, the advances being made in the industry provide numerous options. What is required is careful consideration of what the goals are and if the technology will help to meet them.

This article was based on interviews with Ehrlich, Garven, Heile, LaPierre, McDaid, Shukla, and Williamson.

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