It seems like two or three new wireless technologies are announced every year. And most are touted as the perfect tool to run a Real Time Location System (RTLS).
This non-stop stream of new options can make searching for an RTLS solution really difficult. Here’s the bad news: No single wireless technology is the all-around best for RTLS. For example, the best wireless tech for a staff duress system is usually not the right choice for a key exit alarm system.
But here’s the good news: We have done some research for you, and compiled an Ultimate RTLS Tech Guide, up to date for 2019.
Here we explain just what RTLS is, and then run through the wireless technologies used in these systems. You’ll learn what each does well, so you can make an informed decision about what services are best for your particular use case and facility.
What is RTLS?
Real-Time Location Systems (RTLS), sometimes called Indoor Positioning Systems (IPS) let you track and manage people or assets moving through your facility. Those assets could be loaded pallets passing through a warehouse to your dock. Or sensitive keys not allowed to leave a particular room.
An RTLS uses wireless chips or tags, either attached to, or embedded in, assets for tracking. Those tags communicate with sensors placed throughout your facility to relay location and other asset data to a management app.
Different wireless technologies function in different ways, and so offer different pros and cons. Let’s run through the eight main wireless RTLS standards available today, and review the advantages and disadvantages of each.
1. Active RFID
Radio Frequency Identification (RFID) is one of the more popular wireless standards used in RTLS. Usually the ‘active’ variety, which means the tags carry a small battery to boost signal strength. The receiving sensors determine tag location by calculating signal strength as assets move through a facility.
- No Line of Sight (LOS) Needed—RFID broadcasts in all directions, it’s very easy for nearby sensors to detect signals. This is one of the more reliable RTLS wireless technologies.
- Penetrates Non-metal Solids—This makes assets tracked with RFID difficult to hide. And the technology works reliably in crowded or busy environments.
- Smaller Sensors — Active RFID readers are very small, and can easily be kept out of sight in high security environments, or in customer-facing spaces.
- Again, Penetrates Non-metal Solids—This can also be a problem if determining precise room location matters, as signals can ‘bleed’ through walls or other barriers you may care about. For example, this is not usually the appropriate technology for a duress alert system.
This is a newer ultra-high frequency wireless technology with many interesting applications. You can pack a lot of information into a Gen2IR signal, and the system is highly customizable.
- Highly Accurate—The higher frequency allows detailed, accurate location data to transmit very quickly.
- Fine Signal Control—No LOS is necessary, and readers can easily filter out environmental radiation that might conflict with traditional IR, like sunlight and fluorescent lights.
- Signals Can Be Restricted—Virtual ‘walls’ can be created in a Gen2IR sensor network corresponding to almost any floorplan.
- Infrastructure Requirements—Unlike other RTLS systems, like RFID and WiFi, it’s difficult to ‘piggyback’ on existing wireless infrastructure. New sensor networks are required in most installations. This means it’s best suited for applications like staff duress alerting where pinpoint accuracy to specific rooms is a necessity.
3. Infrared (IR)
Signals are transmitted to sensors via infrared light. Think: TV remotes. Instead of just calculating straight distance, location is also determined by the angle that signals reach receivers. This is an inexpensive technology, but it can be temperamental in ‘busy’ settings.
- Reliability—This is a well-established technology that’s usually cost-effective to deploy.
- LOS Required—Direction matters with IR RTLS systems. Signals can be disrupted by the facing or location of asset tags. Or by mirrors or other reflective surfaces.
- Light-based—Anything that blocks or disrupts visible light will also block IR signals. This limits the technology to smaller, controlled indoor environments with suitable lighting.
4. WiFi Positioning System (WPS)
Many enterprise-grade WiFi systems have positioning capabilities built right into them. Multiple wireless access points measure the relative signal strength of assets to approximate their position inside a facility. This is similar to how GPS works outdoors.
- Integration—Can be deployed in spaces that have existing WiFi coverage with minimal additional hardware.
- No LOS Required—Signals are reliable and hard to disrupt, one of the main reasons WiFi is so widely used for other purposes.
- Bleed Through—WPS is not ideal for precision RTLS, as signals are approximate, and can sometimes register on the wrong side of doors or walls.
- Additional Management—Despite easy integration, this isn’t a ‘free’ service on top of existing WiFi. A fair amount of additional configuration and management is necessary to make it work.
- Sensitive to Changes—While LOS isn’t required, WPS is still very sensitive to environmental changes, which can interfere with its distance estimates. Even things such as opening and closing doors and moving furniture can cause signal distance estimates to fluctuate.
Really only secondarily a positioning standard. Bluetooth was designed primarily as a short range wireless communication system with limited signal quality detection that lets it estimate distances.
- No LOS Needed—Similar to WiFi, but functioning on a much shorter range. Bluetooth signals can pass through clothing and other light materials.
- It’s Everywhere—Most laptops, tablets, smartphones, and other electronics already ship with Bluetooth as a standard component.
- Does Not Scale Well—Due to Bluetooth’s short range, building a network of sensors sufficient to cover more than one room can be prohibitively expensive.
- Future Interference Possible—The standard is popular, and it uses an unlicensed broadcast range, which is likely to become ‘crowded’ in the future with other competing wireless standards.
This is another wireless standard operating in an unlicensed segment of the broadcast spectrum. Its range is slightly greater than Bluetooth, but this comes at the cost of some reliability.
- Simple Technology—ZigBee is an older, relatively simple wireless technology that’s easy to implement in any environment.
- Cost-Effective—Tags and receivers are durable and inexpensive.
- Prone to Disruption—However, the signals can easily degrade in ‘complicated’ environments, and they’re prone to interference. This makes them suitable only for small, simple bursts of information, or for very approximate location services.
7. Ultra-Wide Band (UWB)
This isn’t one frequency, it’s wireless communication spread out over a broad range of the spectrum. This technology is still under active development, so, while promising, options on the market today are still early generation.
- Precision—UWB RTLS is able to deliver accurate positioning information. It can also carry a large amount of other information in short communication bursts.
- Resilient—It’s difficult to disrupt UWB systems, as long as they’re properly deployed.
- Complicated—”If properly deployed” is a major consideration though. The use of a broad spectrum that lends UWB its power also makes it complex to configure in some facilities.
- Some Interference—While most materials will not interfere with UWB RTLS, it can still be disrupted by metallic objects.
- Cost—As an emerging technology, UWB RTLS is often cost-prohibitive for all but very specific applications. For most existing use cases, other systems can deliver similar performance at a lower cost.
Cellular (GSM, CDMA) communication, like for cell phones, can also provide RTLS.
- No Interference—Cellular networks operate in regulated bands, so interference is practically non-existent.
- Wide Range—Offers the greatest read distance of practically any RTLS standard.
- Difficult to Use Indoors—Large, expensive signal repeaters are usually necessary for cellular RTLS to function indoors.
- Lower Relative Accuracy—Compared to other longer distance RTLS systems like WPS it’s accuracy is lower.
Want Further Guidance?
Each of these wireless standards is well-suited for different RTLS functions in business intelligence or security. It just comes down to determining which makes the most sense for your particular use case.
Here at Real Time Networks we’ve standardized on some specific technologies that we think work best in different applications. Active RFID for key location and exit solutions, and Gen2IR for duress alert solutions.