RFID WiFi Radiomap
Searching for the right asset tracking solution can be overwhelming. Within the materials handling and supply chain industry, Radio-Frequency Identifier (RFID) is becoming the go to solution, replacing previous approaches like barcode scanning, but there are other methods that have competitive advantages and technological trade-offs. RFID is one type of technology within the realm of the Internet of Things (IoT). The IoT is a network of devices with sensors and actuators that collect and send data through the Internet. Here we focus on comparing three forms of IoT technology: Passive and Active RFID, and Wi-Fi Radio Mapping.
So, which among the following widely used proximity marketing technologies – Wi-Fi, Radio-Frequency Identifier, Beacons and GPS, will your business benefit from? This is one of the questions that comes up in most of our conversations with customers. Unfortunately, each of these technologies has their own limitations and businesses need to use the right combination of two or more based on their budget and what they are trying to achieve.
Let’s define with the most popular asset tracking technology:
Definition: Technology without an internal power source that uses radio waves created by an RFID reader to send its signal. Passive RFID is the most common form of RFID in warehousing.
Pro: Low-cost (~$0.10 per tag), small in size and weight, and offers a lifetime use up to 20 years.
Con: Expensive Radio-Frequency Identifier signal readers are required (~$10k-$20k per portal), there is a short-read range (tags must be within a few feet of the reader), no sensors enabled, and no memory storage.
To track assets through Passive RFID--as seen in many warehouses today--battery-free tags must be placed on the trackable asset and passed within a few feet of a high-power reader. Passive RFID is a great choice if users are looking for technology that has a long battery life and small footprint. These tags can be as thin as a piece of paper. Additionally, the unit cost of Passive RFID tags can make deploying large quantities of tags affordable. The sizable expense associated with this technology comes from the high-powered readers that are needed, costing upward of $10,000 per reader. For this reason, Passive RFID is normally limited to tracking large volumes of assets through a checkpoint such as gateway reader in an inbound dock. If users are looking to track asset movement continuously throughout a warehouse the reader expense can quickly drive up the cost of Passive RFID.
Definition: Technology that uses battery power to continuously emit a tag’s unique identifier to a given reader. Active RFID is not as common in warehousing as Passive RFID.
Pro: Long read range (up to 300 feet) and lower power readers are needed ($500 - $2,000). Active RFID tags can have sensors and data storage as well.
Con: More expensive per tag (~$20), 3-5 year battery life, larger in size and weight.
Active RFID tags operate by emitting information using its own source of power and can thus interact with inexpensive power-efficient readers. Arguably the largest advantage of Active RFID over Passive is the much longer communication range between the tags and readers. The additional range eliminates the need for Active RFID tags to go through fixed checkpoints as is required with Passive RFID. Additionally, with Active RFID tags, most are sensor-enabled and collect data from the asset. Due to the form factor and technology stack of Active RFID readers, they are not easily integrated with commodity forms of technology or connected to cloud-based systems for big data analytics. While data can be collected, it may be difficult to interpret.
What is Your Goal?
Is your goal to keep track of inventory located in a specific room? If so, passive RFID is probably ideal for you. But if you need to monitor the physical location of a tagged object throughout your entire building, active RFID will be your best bet. It comes down to scalability and functionality. Passive readers can only read tags roughly one to five meters away—so scaling a system that would work for tracking the location of an item would require many readers.
Active RFID tags calculate their location relative to reference points and send this data to nearby readers. The readers then send the location data to the gateway, which is then sent to the solution dashboard. The application takes the data and provides the user with an estimated location of each tagged asset.
If the cost of the tag is the main driver in your decision, passive Radio-Frequency Identifier will win every time. Passive tags are typically between 10 and 50 cents each, whereas active tags range between $5 and $15 each.
How Long Do They Need To Last?
Passive tags are simple they need no battery, meaning they’ll last virtually forever, which is a big part of their appeal. Active RFID tags, on the other hand, typically last between three to five years, with some lasting up to 10 years. While passive is the clear winner when it comes to tag longevity, it’s worth noting that active RFID tags are known to have a much better battery life than some other RTLS technologies (like ultra wide-band and WiFi).
Passive tags are easier to completely seal, which makes them more suitable for more ruggedized environments. Since active tags require batteries, it’s more difficult to ruggedize them. Keep in mind that active tags also cannot always withstand the autoclaving process—so if sterilization is required for your tracking use case, you’ll want to consider all your options.
What Really Works?
In summary, Passive RFID is a great asset tracking solution when cost-per-asset is the priority or when assets only need to be tracked at specific checkpoints. If assets must be tracked across an entire facility for real time location, Active RFID or is Wi-Fi Radiomap the way to go. When easy integration with commodity devices and the Cloud are desired for actionable insights, Wi-Fi Radiomap outperforms the competition. As need and application differ for every facility, time should be spent considering what goals your company looks to accomplish when choosing an IoT asset tracking technology.
We’re currently offer both active passive functionality for a couple of reasons. First, it can provide time-sensitive chokepoint functionality, so we’ll be able to tell more accurately if a tagged item leaves a specific area. Second, it gives those who require active RFID scalability but could use passive RFID functionality when it’s a better option.
WiFi and Radio-Frequency Identifier are two very different technologies and concepts, but they are related in the real-time location system (RTLS) and asset location space. In some cases, the two are used together. For example, an asset location system could use WiFi for data backhaul and RFID for the actual data identification process. Additionally, active RFID and WiFi are both in the 2.4-GHz spectrum.
It’s important to note that in comparing Radio-Frequency Identifier (RFID) to WiFi we’re referring to active RFID and not passive RFID in this comparison. Passive RFID uses high-power readers and battery-free tags and is often used to track assets that go through a chokepoint. There are essentially no comparisons between passive RFID and WiFi asset location systems.
Active Radio-Frequency Identifier: Other active RTLS solutions use a tag (often a Bluetooth or BLE tag) to send out a transmission to a reader. That reader device then transmits the location data to the cloud. As previously mentioned, systems that use active RFID can use WiFi for data backhaul, but it’s not required.
WiFi: In WiFi-based RTLS, the tag has a WiFi radio in it that transfers data out to multiple access points throughout a building or area. The access points use time difference of arrival (TDOA) and differences in signal strength to then compute location and send it to the cloud.
Active Radio-Frequency Identifier: Because of the limited infrastructure, you can deploy a smaller area or function that requires asset location and test it before rolling out a larger deployment. This approach isn’t available with most RTLS solutions, including WiFi.
WiFi RTLS: One of the benefits of using WiFi-based RTLS is that you may be able to use existing WiFi structure with some firmware updates.
Active Radio-Frequency Identifier: Active RFID is usually able to hone in on location with room-level accuracy. One of the drawbacks of active RFID is that the number of readers you have affects your location accuracy. This means greater accuracy will equal greater cost.
WiFi RTLS: WiFi wins the accuracy battle with active RFID as it uses time-of-flight (TOF) measurements with a wider bandwidth. There is a correlation between bandwidth and indoor accuracy—so if you’re doing 80 GHz of 5-GHz WiFi, you can get accurate location positioning within a few meters.
Active Radio-Frequency Identifier: Most active Radio-Frequency Identifier systems don’t require any hardwired infrastructure, making installation very simple.
WiFi RTLS: WiFi location system installation is more difficult. For example, during deployment, you have to survey the area to determine how to calibrate between WiFi access points. This takes manpower and more time than installing an active Radio-Frequency Identifier system.
RFID IT Integration
Active Radio-Frequency Identifier: Active RTLS systems connect to the cloud through a central access point and can be deployed with little to no involvement from the IT team.
WiFi RTLS: WiFi-based RTLS rides on top of your IT structure, so your IT team will have to be heavily involved with getting it up and running.
Active RFID: There’s no way to hack into a data system over the air, making security a non-issue for active RFID.
WiFi RTLS: While RTLS solutions don’t send very much data, there are still security concerns about having unmanaged WiFi end nodes on your network.
There are several similarities between WiFi Radiomap and Active RFID technology. Both operate by emitting their information through battery power to interact with inexpensive power-efficient readers. Both can be sensor-enabled to collect asset data. WiFi readers are however more accessible and scalable than Active Radio-Frequency Identifier readers. A strong advantage of WiFi Radiomap over Radio-Frequency Identifier is its ability to interact with other forms of technology: WiFi Radiomap can easily communicate with day-to-day devices such as smartphones, laptops, and tablets. The sensor-gathered data can be passed between WiFi -enabled devices and uploaded to cloud-based systems resulting in a full-scale IoT ecosystem. This ecosystem can be used to derive insights from the movement of assets over time, to suggest predictive maintenance, and to intelligently prescribe improvements to everything from warehouse layouts to supply chain strategies.