RTLS, or Real Time Location Systems, are combined hardware / software systems that are used to automatically identify the location of objects or people inside of buildings.  
Typically, RTLS systems are used within contained areas to keep track of where every asset of interest is at any given time.  The goal of using a system like this is to constantly know the location (and in some instances, the state) of the various assets you need to track.  

There are three components to every RTLS system: First, the physical infrastructure, or “backbone” that includes the many fixed reference points, repeaters and readers that blanket the facility; Second, the active or passive RFID (radio frequency identification) tags which are attached to objects or people and communicate with the backbone ; and finally, a software layer that collects data, compiles everything together and presents it to end users in a visual layout.

How RTLS Works

Backbone

There are numerous different types of RTLS systems being implemented in a variety of industries.  Primarily they fall into three categories:

Wifi Based:  

These system take advantage of Wi-Fi networks and leverage signal strength readings (or triangulation) to calculate the locations of objects in a building.  

Optical Based (Infrared):  

The building is outfitted with infrared beacons in areas of interest - for example in hallways, inside rooms or closets and at exits.  These beacons excite tags on objects as they pass beneath them and communicate the tag ID back to the software layer.

 For example, Imagine a nurse walking into a patient’s room rolling a portable IV pump that has been equipped with a tag.  The IV pump rolls under the infrared beacon, the beacon excites the tag, captures the tag ID and transmits the tag ID back to the software (either wirelessly or via ethernet cable).  This approach allows staff to know the exact location of all IV pumps in the facility at any given time.

Acoustic Based (Ultrasound):  

Ultrasound locating technologies work similarly to infrared systems only they use ultrasound beacons deployed in locations of interest.  They can pinpoint the location of tagged resources with in-room precision to deliver clinically and operationally significant location information, device status, or environmental data in real-time.

 All of these systems must first set up pathways to get information back to the centralized software layer.  Generally this is done by wifi, other wireless frequencies, or hard-wired ethernet cables.

Tags

Wireless RFID (radio frequency identification) tags are attached to objects or worn by people.  These tags, which have unique identifiers, interact with the physical infrastructure, or reference points, scattered throughout the building.  Information kept about the tags in the software layer identifies the type of object, its characteristics, rules surrounding the type of tag (for example, Alzheimer patient’s cannot leave the building) and alert methodologies (who should be notified when the medical oxygen storage closet in the emergency room needs to be refilled).  

The two types of tags commonly used are passive and active.  

 Active RFID Tags are powered by a battery and automatically broadcast their signal to the reference points

Passive RFID Tags do not have a power source and only transmit a signal upon receiving energy emitted from a reader in proximity of the tag (for example, walking under an infrared beacon).  

In certain instances, these tags also have the ability to identify and broadcast the object’s state.  For example, RFID tags can be integrated with sensors that have the capability to sense temperature, humidity, and even the pressure of items such as medical oxygen tanks.  When a medical oxygen tank runs low, it can broadcast not only its location, but also that is empty.  This type of insight allows for significant improvements in process, costs savings and the reduction in the number of capital assets required.

Software

All of this information is made useful by the software layer.  Generally delivered to the end user in a floorplan-based user interface, users can search for types of objects, locate specific items and run reports to identify trends and patterns.

 RTLS software has been primarily used to track the location of assets, and as such organizations with multiple, high-value, constantly moving assets like hospitals have found the solution to be extremely beneficial resulting in rapid (6 - 12 month) return on investment.  

 Simply put, it pays to know where everything is.  Whether it’s medical O2 tanks, forklifts, laptops, or IV pumps, knowing where your assets are saves business operators time, money, and energy.  Stay tuned for upcoming posts on the benefits of RTLS in hospitals and how it generates ROI.