Wireless Sensor Network 

Wi-Fi

The battery-based Wi-Fi tags can be deployed as asset tags or reference tags. Facilities that already have a Wi-Fi Infrastructure in place can take advantage of the reference tags to save time and money. The deployment of reference tags is as simple as attaching them to a wall or ceiling without power or data cabling requirements. Because reference tags are not access points, RF network planning does not need to be revisited.

Reference tags form a peer-to-peer network and enable asset tags to use Relative Signal Strength (RSSI) and Time of Flight (TOF) to determine their location. This enables a facility to extend the Wi-Fi RTLS with high accuracy into areas that may not have robust or any WLAN coverage, without the expense and man-hours associated with adding costly access points.

Reference tags act as the "eyes" of the RF Network, providing runtime calibration and sample points, as well as enabling the location engine to update its algorithms based on the dynamic information, in the event that the RF environment changes.

Avoids operational disruptions and additional access points requirements  for increased accuracy, which eliminates any re-planning or additional calibration of existing Wi-Fi networks.

Peer-to-Peer Wi-Fi Tags will work seamlessly with the Wi-Fi access point infrastructure of any vendor; therefore, the cost and deployment time needed to make an RTLS Asset Location-Aware System a reality is substantially reduced.

ZigBee-Based Active RFID-RTLS

RFID-RTLS systems based on underlying ZigBee technology are getting a lot of attention, particularly in the healthcare market. A ZigBee mesh network is self configuring and self healing, maximizing reliability and minimizing the cost of network deployment and maintenance. Bridges connect the wireless ZigBee network of sensors to the enterprise LAN (via either wired Ethernet or Wi-Fi).

Active RFID tags are attached to assets (equipment or people), sending brief transmissions every 5 seconds (for tags in motion) and every 10 minutes (for tags not in motion). Sensors transmit every 60 seconds to measure RF variability in the area under observation and calibrate the system. The frequency of these updates is key in minimizing environmental variables and maximizing positioning reliability. Analysis by a positioning engine results in the precise tag location, which is viewable on a web-based search application.

Using underlying ZigBee technology and patented computational algorithms, RTLS returns asset location within 1-3 meters, providing room level accuracy. The configuration of the sensor network further eliminates “floor hopping” which can be an issue with Wi-Fi based deployments. ZigBee network technology is the best suited underlying technology for active RFID-RTLS deployments for a variety of reasons. Purpose-built ZigBee networks based on the IEEE 802.15.4 standard provide the lowest-cost implementation of sensor networks.

The RFID-RTLS ZigBee based solution requires no cabling infrastructure, offering a truly dust-free installation; and provides the longest battery life for mobile tag nodes, due to low-complexity, low transmission power, and low data rates. This low data rate ZigBee wireless sensor network is complementary to other networks deployed in various industries, cost-effectively delivering real-time location, status and movement of equipment and people into the overall environment.