On Wireless

Oct 1, 2008 12:00 PM, By Beck Ireland, Staff Writer

Overcoming incompatibility and improving throughput in wireless data systems applications for non-residential construction markets.

Feb. 17, 2009, may mark the beginning of a radical change to the wireless data systems industry. Under the Digital Television Transition and Public Safety Act of 2005, it's the date when full-power analog television transmissions will cease, opening up the 746- to 806-MHz frequency spectrum for auction. “Right now there's a lot of talk about what's going to be done with that bandwidth,” says Joe Bardwell, chief scientist and president, Connect802 Corp., San Ramon, Calif. “The 700-MHz spectrum has tremendous range because it's a low frequency, relatively speaking. It may be possible for data communications to operate over a range of multiple miles, penetrating inside buildings in the same way you can pick up the TV station signal from a broadcast antenna 40 miles away.”

Under those circumstances, according to Bardwell, it would be possible for a single wireless infrastructure at an industrial facility, for example, to simultaneously support industrial process control, video, and Voice over Internet Protocol (VoIP). “That's the fantasy right now, and it's exciting,” Bardwell says. “Once the electrical engineers and mathematicians figure out how to encode and decode a higher data rate in a way that is commercially viable, then we'll see the next evolution in wireless datacom (see The Evolution of Wireless Communications on pages 32, 34, and 36). Five years from now, this might be a whole new ball game.” Until that time, wireless data systems manufacturers, designers, and installers must overcome issues of compatibility and throughput inherent in the technology.

The wireless data systems industry falls under the jurisdiction of a three-pronged process that includes: the legal requirements of Part 15 of the U.S. Federal Communications Commission (FCC); the engineering standard of the Institute of Electrical and Electronics Engineers, Piscataway, N.J., IEEE 802.11-2007 and its amendments for wireless local area networks (WLAN) computer communications; and the interoperability benchmarks of the Wireless Ethernet Compatibility Association. This group is informally called the Wi-Fi Alliance, Austin, Texas, a nonprofit organization with the goal of driving the adoption of a single worldwide accepted standard for high-speed wireless LAN. “IEEE sets the standard that complies with the FCC's regulatory requirements, and then manufacturers build to that standard,” Bardwell says. “But because the IEEE standard specifies what you have to do but not how you do it, there's the Wi-Fi Alliance to test interoperability, making sure that one manufacturer's implementation of the IEEE standard is compatible with the other manufacturers.”

The IEEE 802.11-2007 standard, which is overseen by the IEEE's Computer Society's Local Area Network (LAN)/Metropolitan Area Network (MAN) Standards Committee, contains rules to avoid radio frequency (RF) collisions. Twelve months after their publication date, the IEEE makes these standards available for download on its Web site at http://standards.ieee.org/getieee802/. “An 802.11 device is supposed to work with other 802.11 devices that are out there,” says John Colodny, president and CEO of Wiring.com, Inc., Sunrise, Fla., a company that provides wireless and cabling systems in the health-care, institutional, and industrial markets. In addition, amendments to the standard have helped refine the technology. Yet, overcoming shortfalls in the technology remains a design challenge. “It's a contention medium,” Colodny says. “All the devices are contending for the access point at the same time. Only one can communicate with an access point at one discrete moment in time.”

Guest services

Wireless applications for different market segments pose their own challenges, on both the component side and in the cabling infrastructure. “From a design standpoint, everything starts with the application, and then the application determines how much bandwidth is required,” Colodny says. “That's the biggest difference between a wired network versus a wireless network. In a wired network for low-voltage communications, typically everything is standards based — Cat. 5e, Cat. 6, Cat. 6a — so the applications aren't usually identified to the contractor or discussed. In a wireless network, everything starts with the application because it has bandwidth requirements. A wireless network has to be designed to support the applications and their required bandwidths.”

Therefore, designing and installing a wireless network for a commercial building can differ vastly from what is required by a health-care facility or industrial processing plant. Typically, wireless networks for commercial and multi-family residential, such as urban condominiums, are geared toward a guest experience, which includes the availability of cell phone service and wireless Internet. “From a wireless perspective, most commercial facilities are looking for wireless local area network (WLAN), and that provides your Wi-Fi, your basic connection to the network,” says Tony Whaley, vice president of global design firm RTKL, Baltimore.

A common technology used to enhance the WLAN is a distributed antenna system (DAS), which allows cell phone connectivity even within large structures. “I'm sure you've experienced going into buildings where your cell phone just won't work,” says Tom Fox, an associate in the Special Systems Design Group at RTKL who maintains that DAS is almost becoming a necessity in large condominium-type spaces for young urban professionals. “The DAS system alleviates that issue.”

A few years ago, basic Wi-Fi and cell phone service was enough for hotels and hospitality facilities. However, improvements to technology and tech-savvier guests are now requiring some to retrofit to bigger systems. “I was involved in a project a year ago where 300 major hotels that already had Wi-Fi were retrofitting because they had received enough consistent complaints from the guests,” Bardwell says. “When they'd installed the system a few years ago, they were providing some basic e-mail support for the business traveler, but over a period of time, the traveling public has come to expect more.”

Visitors have become used to surfing the Web for restaurant and menu options, as well as downloading maps and checking the weather. There is also a new technology that allows travelers to connect through the Internet to watch shows from their hometown. “It lets you connect to it through the Internet so you can watch your local television shows while you're traveling,” Bardwell says. “That's popular for the international business market, but it puts a huge load on the network, because they're feeding IP television across the network.”

In contrast, resort hospitality facilities are for the most part staying with basic services. “There is a segment of the hospitality space, particularly the resort space, where the wireless network can be designed to a minimum level of capacity,” Bardwell says.

For example, Bardwell's company recently installed Wi-Fi at a summer camp on Lake Tahoe. The owners wanted only basic e-mail connectivity, trying to encourage its guests to relax instead of work.

A common denominator for wireless systems in all markets is that VoIP requires the strictest and most rigorous specifications. Therefore, when designed to support VoIP, the network should have the maximum capabilities to support voice. “As a result, whatever else that customer happens to be doing is not going to be as demanding on the network as the wireless VoIP,” Bardwell says.

The most common uses of wireless VoIP is employee communication, whether with the forklift operators in your plant or the nurse on rounds. “Wireless VoIP is an established technology,” says Bardwell. “Prior to that, these applications would have been handled with products like push-to-talk cellular. But if you're paying monthly costs to have 100 or 200 employees connected, that's a huge cost. So, one of the motivations for putting wireless VoIP into a building is to mitigate the cost by building out a privately owned voice communication system.”

An emerging technology that could eventually enhance the capabilities of VoIP is fixed mobile convergence (FMC). “FMC speaks to roaming off of the cellular network and roaming onto an in-building Wi-Fi network,” Bardwell explains. “It's under the umbrella that we could call ‘ubiquitous connectivity’ for voice and video and data. Kids today will look back and say, ‘I remember when voice, video, and data were separate.’ But 20 years from now, there will be ubiquitous connectivity for voice, video, and data.”