Controls: 6 Keys to Wireless Systems
Part 2: WiFi, Zigbee, EnOcean Are Most Common Wireless Technologies
WiFi, Zigbee, EnOcean Are Most Common Wireless Technologies
By Gislene D. Weig - March 2013 - Building Automation
1. Technology Options. The most common wireless technologies used in building automation systems are WiFi, ZigBee, and EnOcean. Building owners can benefit from the use of multiple wireless technologies across different network levels within the BAS to leverage the differences in high data throughput, cost, and flexibility that each technology can offer.
WiFi provides higher bandwidth capacity, but is typically more expensive and consumes more power than EnOcean and ZigBee.
ZigBee provides medium bandwidth capacity, but consumes less power than WiFi and is generally less expensive. The maximum data rate specified by IEEE standard 802.15.4, which is the basis for ZigBee, is 250Kbps. As a result, this option is well-suited for applications that require low data rates. It also means a longer battery life. ZigBee operates at the same frequency as WiFi (2.4GHz) in most places around the world, but can co-exist with WiFi networks even though both technologies use the same industrial, scientific and medical (ISM) band.
EnOcean uses battery-free wireless devices because it has an ultralow bandwidth capacity with low power consumption. It operates on a different frequency than WiFi and ZigBee.
2. System Reliability. Wireless systems are expected to have the same level of reliability as wired systems, including the ability to send and receive data continuously within a threshold of time and delay, and with minimum error. These threshold parameters will depend on how the network is set up. Engaging an IT consultant to set up the network properly can help ensure the reliability of the network.
Wireless can be as reliable and secure as a wired network, but that requires proper planning and implementation. By implementing a wireless mesh network with "smart" routing techniques, challenges like ensuring data packets successfully reach their destination can be mitigated.
3. Wireless Link. Construction materials and obstructions have a significant effect on the reliability and strength of a wireless link. These factors determine the allowable distances between the transmitter and receivers, and the need for repeaters throughout the building. Materials such as drywall and wood are excellent mediums for wireless signal propagation. On the other hand, I-beams, elevator shafts and metals make it difficult for the wireless signal to propagate. Therefore, the building's characteristics must be considered during the design layout of a wireless network. Wireless solution providers should conduct site surveys to assess design details in order to determine coverage, bandwidth performance, device options and quantities, and antenna locations to guarantee the coverage, quality, and strength of radio frequency signals. For new construction, a wireless solution provider should use mapping tools to generate a prediction map and proposed design layout.