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.”
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.”
Health-care facilities are interested in providing a guest experience for their patients and visitors, but in addition to that, they require many more applications and systems. “Installing cabling in health-care facilities, particularly as a retrofit, with fire protection, infection control, and patient care concerns, is very structured and regulated,” Colodny says.
In the hospital setting, lives may not only be depending on the network, but the network must also ensure privacy. “The guiding principle is consistent connectivity because the wireless network provides support for patient care, so it's the criticality of the design at any data rate,” Bardwell says. “The other aspect is security for the network, particularly because of the privacy rule of the Health Insurance Portability and Accountability Act (HIPAA) requirements.”
Wireless applications for health-care facilities range from barcode scanning, data storage, patient telemetry, and equipment tracking, as well as communications, which can cause compatibility issues. “When you go into a medical facility, you have to not only encompass the regular Wi-Fi or WLAN, but there are public safety radios, wireless ID systems, and wireless medical telemetry systems,” says Whaley. “It becomes more complicated when you're dealing with hospitals as well as with government agencies.”
Most hospital workers are equipped with a communication device, which may run on the 900-MHz frequency band, which is the unlicensed frequency band known as “industrial, scientific, and medical (ISM),” in the 900-MHz, 2.4-GHz and 5.8-GHz range. Devices in close proximity using the same 900 MHz band — microwave ovens, cordless phones, Bluetooth-enabled cell phones — may interfere with network operations, which is why most emergency rooms ban cell phone use.
Wireless networks for the industrial segment pose their own unique challenges, in addition to system compatibility and interference. “In warehouse and manufacturing, because the space is generally huge, there is often sticker shock when a customer finds out how many access points they will need if they want maximum capacity coverage in 2 million square feet,” Bardwell says. “That's a lot of access points.”
However, cost can be scaled back by resorting to only necessary applications. The most common wireless application for warehouse and manufacturing facilities is the handheld inventory scanner. As a result, they often don't need the highest capacity network. “They're not supporting Web browsing and e-mail as their primary activity,” Bardwell says. “It's a very small amount of data that's being transferred, so warehouse and manufacturing networks can be designed to a lower level of coverage because there's generally less need for high capacity.”
Begin at the beginning
For plants that require higher capacity for process controls and security, for example, managing disparate wireless applications that may operate on different frequencies or have conflicting standards — Zigbee, Wi-Fi, Wi-Max, RFID, VoIP, Bluetooth, Mesh Networks — begins in the pre-planning phase. “You have to be careful about the RFID,” Whaley says. “Most of those are proprietary systems, so it can be very complicated. Good design is in mixing those various systems, making sure you have the right brand or product for the client, and making sure it's going to live harmoniously in an RF world.”
The type of access points — single, dual, multiple-in-multiple-out (MIMO) — and other design considerations will be determined by the applications as well as scalability, the ability of the network to expand to cover future needs. “The customer needs to make a decision based on current and future applications and how much bandwidth is going to be required,” Colodny says.
Whaley agrees. Because wireless technology improves at such a rapid rate, you have to build an infrastructure for your client that can be enhanced down the road. “They make all these different systems backward compatible, and you integrate it,” he says. “You plan for the growth of the client's facility and for wireless technology by making sure you have a good infrastructure for your clients.”
A common mistake owners often make is to think of including a wireless network after construction has begun. “The best case is that the wireless network design is created before the cable system is installed so that all of the cable runs for the wireless equipment can be pulled along with any Ethernet or telephone that's being pulled in the building,” Bardwell says. “That way, the installation contractor can do all the cable pulls ahead of time without having to go back and retrofit and move ceiling tiles and open walls.”
Wireless systems in new construction can also be modeled using 3D CAD. “We can actually model that building with wireless software and give a general idea what propagation is going to be like within that building before it's built,” Whaley says. “Once the building starts to get built, we work with the construction team to do onsite surveys as well as planning for the wireless infrastructure. It's constructed simultaneously with the new building. Once the building is completed, just like you would do with mechanical and electrical systems where you commission the systems, we'll commission the wireless systems and other telecommunications systems.”
Currently, most wireless network projects are retrofit. “Unfortunately, very few facilities folks, whether they are the general contractor, the architect, the owner, or the project manager, stumble upon the fact that the wireless network should be designed and rolled out as the building is being built,” Bardwell says. “So often it's the case that it isn't until the building has tenants that they begin to talk about it. It would have been nice if they thought of that a year prior, when the building was still on the drawing board.”
There are techniques to create a successful design and installation in a retrofit project. Most firms conduct site surveys. “We go in with mobile equipment to verify the RF characteristics of the building, and how many access points are needed/where they need to be placed to provide the required bandwidth,” Colodny says. “A field site survey is done with the wireless components prior to installation. There's also another method called predictive analysis, which uses computer simulations to determine where the access points need to go, but predictive analysis is not as good as going into the field and doing it for real. One is a simulation; one is actual results.”
Recently, RTKL performed an RF assessment site survey for the City of San Jose, Calif. “We had 3,000 test locations so they could get a snapshot of if their public safety radios would work and their cell phone reinforcement,” Whaley says. “Those assessments can be critical, and the key for us to be able to give people what they need as far as good, clean wireless communications.”
There are several credentials for wireless data systems designers and installers. Tampa, Fla.-based BICSI is a professional association supporting the information transport systems (ITS) industry with information, education, and knowledge assessment for individuals and companies. It serves more than 24,000 ITS professionals, including designers, installers, and technicians who provide the fundamental infrastructure for telecommunications, audio/video, life safety, and automation systems. In addition to providing professionals with a useful tool for wireless design in the form of its “Wiring Design Reference Manual,” BICSI offers various certification credentials, including Registered Communications Distribution Designer (RCDD), Network Transport Systems (NTS), Wireless Design (WD) specialist, and ITS Cabling Installation credentials.
There are several exams to take regarding the 802.11 standard, including the Smyrna, Ga.-based Certified Wireless Network Professional's (CWNP) Certified Wireless Network Administrator (CWNA) and Certified Wireless Network Expert (CWNE) credentials. In addition, there are many manufacturer-sponsored certifications for their proprietary systems. “Interestingly, there's some crossover,” Bardwell says. “BICSI wireless certification includes things that a structured wiring person would need to know about wireless, whereas the CWNP certification includes things about RF wave propagation and antenna patterns, which a structured wiring person wouldn't necessarily have to be as well versed in.”
Bardwell's company uses a network of installation contractors throughout the country. It makes sure the contractors understand the fundamentals of pulling wire for wireless, particularly Arlington, Va.-based Telecommunications Industry Association (TIA) 568B. “The electrical contractor that thinks network cabling is like pulling telephone wire is in trouble, because it's going to pull a whole building and the computer network's not going to work,” he says. “But thank you, BICSI, because now there are some electrical contractors that could be considered experts at network cabling.”
The RTKL Special Systems Design has witnessed its share of difficult installations as well. “I've watched it get done two or three times before it's done right,” Whaley says. “You have to take care that you have the proper infrastructure and the proper separation from other cables, because this is going to radiate out. You have to make sure you have the proper shielding and the proper grounding. So you need a professional that understands how wireless is supposed to go into a facility — just like you need a professional that understands fiber or high-voltage cabling.”