“Can you hear me now?” That question, posed in popular cell phone advertisements, is a humorous touchstone for a generation whose ability to communicate wirelessly is dependent on network coverage. Nothing means mobility more than wireless, and wireless is only as good as its network coverage.
Today’s building owners, managers and tenants have come to expect laptop connectivity wherever they roam and unobstructed control for everything from heating, ventilating and air conditioning (HVAC) to security and life safety to lighting systems. Whether it’s a new building or the expansion of an existing wireless system, contractors planning and installing systems that deliver these benefits have to answer a similar question: How do you set up a wireless network so that all areas are covered?
According to Graham Martin, chairman and CEO of the EnOcean Alliance, the answer to proper coverage lies in the recognition that wireless networks still require cabling, yet they provide maximum flexibility as they can be moved according to users’ changing requirements.
“Full network coverage is very easy to plan and to measure practically on-site using simple tools showing wireless signal strengths,” Martin said.
Establishing wireless networks to operate and monitor technologies, such as controllers, sensors and switches, is not much different than the wireless networks we set up in our homes. However, they must be more reliable and flexible and consume less power.
Created in 2008, the 150-member EnOcean Alliance is a consortium of European and North American companies working to develop and promote self-powered wireless monitoring and control systems for sustainable buildings through formalization of an interoperable wireless standard.
Develop the hybrid plan
At the heart of solving the coverage issue is developing a strategic deployment plan that includes a site survey, spectrum analysis, list of applications, protocol selection and compliance with standards. The first phase of the wireless lifecycle is preparing for the installation of a new wireless network or the expansion of an existing wireless local area network (WLAN).
A variety of site survey tools allow contractors to simulate a wireless network before purchasing any access points (APs). WLAN-planning software enables installers to import a map of a site and add virtual APs, virtual walls and other features. A key step is determining the ideal quantity and location of APs required to meet performance criteria. Radio frequency (RF) spectrum analyzers can help detect, identify and locate RF interfering devices.
And, it must be remembered here that wireless does not really mean wireless. WLAN systems rely on wired infrastructure. Every AP has to be hardwired to the network in a local telecom room or main equipment room using fiber or unshielded twisted-pair (UTP) cabling, and it must be powered. Certain APs are designed to operate on power over Ethernet (PoE), while some contractors prefer AC power or a separate UTP cable. With fiber forming the backbones of most corporate networks, the jump to Wi-Fi is not that big of a deal anymore, and upgrades can usually consist of replacing APs without recabling.
However, plenty of technicalities exist, and this fact presents one of the biggest challenges in wireless networking: maintaining simplicity. Enabling any installer or contractor with the tools and know-how to easily and seamlessly integrate the systems into common building management systems such as LONWorks, BACnet or TCP/Internet protocol is a common goal.
Rich Black, Lutron product development manager, said the design of the wired portion is equally as important as the wireless portion, and hybrid devices can accommodate all types of new and retrofit applications.
“The electrical contractors will need to be involved in the design phase to fully understand how the system will be wired and which locations require wireless. For optimal coverage, a distributed system can be utilized, which will require the electrical contractors to separate the building into logical sections by considering available equipment rooms and the required equipment and networks associated with each section,” Black said.
According to Michael Regelski, CTO, Global Security Products, UTC Fire & Security, the predeployment plan should expose potential system vulnerabilities.
“Proper wireless coverage with access points and/or repeaters to ensure a strong signal strength between the endpoints and communication hubs are vital. Additionally, the wireless system needs to provide security and data encryption and frequency agility to ensure reliable communication and the utilization of standards to comply with IT infrastructure,” Regelski said.
Anticipate coverage problems
Wireless coverage can get tricky depending on the floor plan’s impact on signal range and absorption. Generally, materials that present bigger challenges to RF performance are large expanses of concrete or metal around elevator areas, ductwork and fireproof walls and doors.
Coverage problems also typically relate to the layout and environment in which devices are located. Building composition—such as thick, dense walls, long corridors and basements—present more problems with distributing wireless transmission signals. Likewise, environmental conditions and sources of radio frequency interference, such as WLANs, X-ray equipment in hospitals, mobile and cellular phones and microwave ovens, can compromise the integrity of signal strength.
“Wireless LANs are everywhere within a building, so it’s essential to avoid the 2.4 GHz frequency band they communicate in,” said EnOcean’s Martin. “The lower the frequency, the longer the signal range, so using a sub 1 GHz frequency band is absolutely essential.”
According to Lutron’s Black, bandwidth is an increasingly frustrating problem with wireless sensor networking.
“A higher density of RF devices are competing for a limited amount of frequency bandwidth,” Black said.
IEEE 802.11 is the standard for wireless, but the increasing traffic from an array of devices and users and networks that must share the same bandwidth, has created congestion. The 802.11n standard for Wi-Fi is 600 megabits per second (Mbps) of bandwidth in the best of usage conditions, but that shrinks significantly with heavy usage. Making things even more difficult, 802.11n allows for the interpretation of reflections as a pathway for communication signals.
What happens once a wireless network is installed? Following installation, less-network experienced contractors could use a new handheld tool from Fluke Networks to verify and troubleshoot a host of 802.11 a/b/g/n network issues. The AirCheck Wi-Fi tester enables users to identify coverage and connectivity problems, find unauthorized or rogue APs, see overloaded networks and channels, detect interference, and validate security settings.
What advantages do your systems provide to building owners/managers?
Rich Black, Lutron product development manager:
“Lutron’s whole-building lighting control systems provide owners and managers the ability to control and monitor both the natural and electric light from any location in real time. Lutron’s ClearConnect wireless technology utilizes a frequency-agile, fixed repeater network operating in a low-traffic frequency band. The operating frequency is low, which is attenuated less through heavy construction materials. The result is a fast, predictable and ultra-reliable wireless system.”
Michael Regelski, UTC Fire & Security CTO, Global Security Products:
“Some of the big differentiators that we provide are frequency agility to ensure reliable communication and transmission of mission-critical information, low-power electronics technology and optimized communication protocols to maximize battery life and battery-life diagnostics, and indicators based on the actual usage.”
Arif Kareem, Fluke Networks president:
“Companies are increasingly reliant on Wi-Fi networks, but many continue to see them as less reliable than wired alternatives. This is partly because time- and resource-pressured IT personnel do not necessarily have the training or the tools they need to monitor and troubleshoot network issues. AirCheck addresses the requirement to arm frontline IT personnel with an affordable easy-to-use portable tool that provides comprehensive WLAN visibility across all Wi-Fi standards.”
Graham Martin, EnOcean chairman and CEO:
“The EnOcean wireless protocol eliminates the need for batteries, so there is no tedious, expensive and environmentally unfriendly battery maintenance. The protocol uses 315 MHz frequency so is much higher range and has much less interference than wireless systems at 2.4 GHz. The protocol is an international open standard enabling full interoperability between products from different manufacturers. It has been proven in around 250,000 building projects—more than any other low-power wireless protocol.”
Lutron’s Black believes wireless networks will continue to be a popular solution.
“There is an increased demand for interconnectivity and interoperability between disparate systems, both wired and wireless. Technologies are being developed for the purpose of bridging separate networks or unifying all devices to a common protocol,” Black said.
A new open protocol developed by the EnOcean Alliance is solving one of the biggest issues in wireless sensor and switch networking for building automation. Wireless energy harvesting is a technology that sources the existing environment for energy rather than conventional electricity or batteries.
“Every switch or sensor within a building powered by cable requires typically an average of 15 to 20 feet of copper/PVC cable. Eliminating the cable reduces the amount of natural resources required and the CO2 output required to manufacture the cable,” EnOcean’s Martin said.
Martin explained that the consortium’s energy-harvesting wireless sensor modules feature energy converters, low-power electronic circuitry and a wireless protocol. Transmitted over the 868 MHz or 315 MHz frequency bands for global use, the wireless signals are one millisecond long, approximately one hundred times shorter than those of conventional wireless switches. Products and systems incorporating EnOcean technology integrate into LonWorks, KNX, BACnet, TCP/IP or Ethernet.
“All wireless protocols have their application sweet spot, e.g., WLAN, Bluetooth and ZigBee. The EnOcean standard is the only wireless system designed and built for battery-less and maintenance-free operation, having its sweet spot in controlling and monitoring in energy-efficient buildings,” Martin said.
Wireless networks with full coverage coupled with energy-saving devices are clearly the future, and contractors can position themselves to take a leading-edge role.
“In the not too distant future, Wi-Fi will be the ubiquitous wireless infrastructure for buildings and communities, providing the possibility of fully connected wireless systems. This trend will place a premium on application security and low-power electronics,” Regelski said.
MCCLUNG, owner of Woodland Communications, is a construction writer from Iowa. She can be reached at email@example.com.