ARS Solutions for Healthcare: WiFi Tracking System

Background:

Healthcare organizations today increasingly need a thoroughly reliable, low-cost solution to their high-value asset-tracking needs. Active RFID Systems, Inc. 433.92 MHz solutions are designed to allow healthcare institutions increase patient safety and throughput, optimize asset and resource management, synchronize workflows, and reduce operational costs. .

ARS has developed a family of tracking systems that are not only very inexpensive but also exceptionally easy to install and setup. The low cost is achieved through the following:

  The system is operable by “plugging” trigger assemblies directly into existing 110/220 VAC power outlets. This requires no additional permanent building infrastructure. Location is determined by the physical identification of the trigger locations. The system utilizes an adaptation of ARS' low cost, dual-mode infrared/RF tags.

  All communications and data-forwarding are performed wirelessly, with no loss of data and no network set-up costs.

  The system does not require new wiring or expensive location mapping, since the location mapping is consistent with building walls and power outlets.

  Our proprietary system of infrared triggers results in years of battery life on the tags as opposed to months with competitive systems.

System Description:

The baseline system employs two basic components:

1. Dual mode infrared/RF tags, which incorporate an infrared sensor that responds to an incoming coded signal in such a way that the tag will transmit an RF output signal when it is in the vicinity (range) of an infrastructure-mounted device. The output consists of the tag identification (ID) value and the identification of the infrared transmitting unit. Thus the RF output serves to identify both the item (or person) and the location with a single transmission.
   
   
2. Wall mounted trigger assemblies, designed to be powered from wall transformers that are “plugged into” the common wall outlets for 110/220 VAC power sources, thus obviating the need for hard wiring. These devices incorporate a number of infrared signal transmitters and are continuously emitting the coded infrared signals that the tags respond to. The power of these infrared emitters is controllable with handheld devices such as PDAs, laptops or Active RFID Systems, Inc. controllers. The power of these emitters determines the range of the system and can be adjusted from several inches to tens of feet. In this manner a near spherical volume of “engagement zone” is created. Within this “engagement zone” any tag will be triggered and the reception of this signal received by the 802.11.b/g network.

The infrared signals are pervasive and do not require line-of-sight to actuate tags.

When a tag is in the vicinity of an infrared device, the tag transmits the 802.11.b/g 2.45 GHz “payload” of data to the existing network.

The figure below is incorporated as an illustration of the basic operating principles of this system.

In the ARS system, the wall-mounted triggers are shown (marked as IDs 1 through 4) fixed to wall outlets in the vicinity of the items to be monitored. These readers emit a continuous encoded infrared signal that is transmitted hemi-spherically (shown in blue gradient and defined above as the “engagement zone”) from each trigger device. These signals can be adjusted for approximate range; however, it is likely that signals will occasionally “spillover” into another reader's range. The system hardware enables manual adjustments of these infrared signals.

When the tags (shown in red) receive an infrared signal they transmit an 802.11.b/g signal (illustrated in green) to the access points. (For areas in which there is no 802.11.b coverage, Active RFID Systems, Inc. can also supply both access points and relays.) This signal may be received by a multitude of access points. However, since this signal packet contains both trigger signal ID as well as tag ID, the database algorithm recognizes the tag as being in a particular trigger's sphere of influence. Again, there will occasionally be overlap due to infrared signal spillover, in which case the location will be noted as within multiples of the trigger's range. Continuous receipt of a trigger signal will cause the tag to remain RF silent except for periodic updates.

The triggers can also be set up to form a “wall” at portals enabling the tracking of items that are entering or exiting through such a portal opening.