Let’s explore the concept of what we refer to as an “RFID Read Zone based approach” to implementing RFID asset tracking.
In today’s warehouse or office environment, we often take for granted that there’s always a WiFi signal flowing all around us. Unfortunately, there is a common misconception that RFID should work like a WiFi network and cover an entire facility with real-time tracking. RFID has the potential to cover a very large area — possibly your entire facility — but the costs are prohibitive. In most of the cases that we have seen it does not make economic sense to cover an entire facility with RFID like a WiFi network.
For a number of years now, A2B Tracking has been developing the technology that leverages the use of a read zone based approach to implementing RFID. Utilizing read zones is a much more economically efficient system because it focuses on asset movement in addition to current location.
Focusing on asset movement requires consideration of your facility layout and identifying key choke-points or portals where your assets are forced to travel through. Positioning your fixed RFID readers in these strategic locations, or read zones, allows you to be able to capture your assets with passive RFID tags as they move through a choke-point and into a new location.
As an example, let’s use an item that leaves the receiving dock and enters the warehouse. Let’s assume that there is some sort of an egress (either a doorway, or a hallway of some sort) between these two locations. If the passive RFID tags are captured as the item moves through that egress, or RFID read zone, a new location will be assigned to that asset. This is referred to as the “last known location”.
Fixed readers that are located strategically at choke-points in your facility will capture your asset movements and provide you with real-time updates of your assets’ last known location. This allows you to break your facility down into locations separated by read zones. With the knowledge of the last known location and then using mobile computing capabilities such as your smartphone, we can quickly identify exactly where that item is within that smaller, more manageable area.
This two-stepped approach is the most economical and effective way to implement RFID asset tracking. The picture below shows a part of the A2B Tracking facility as an example of RFID read zones. You will notice that we have multiple office and warehouse areas and that we have broken our facility down into separate locations. Each location is separated either by a doorway or a hallway, where our assets are forced to travel through.
The assets have to travel through a choke-point in order to get to a new location, whether it is a room, a storage area, or even into a tool crib. And every choke-point, or portal has fixed RFID readers in place to capture any movement of assets with RFID tags.
As a side note, zones and choke-points can be created without actual doorways or walls. If you’re looking for visibility of pallets moving around a warehouse, or items moving through a production line on a factory floor — these can also be established with zones. But, you will need to be strategic and carefully consider the flow of assets to establish your chokepoints and capture the data that you need.
The good news here is that with a read zone based approach to RFID you can control the size of your location with as many readers as you need. Using strategic points throughout your facility you can get visibility down to a granular location or less visibility in a much broader location. Ultimately, this approach allows you to control how much you want to invest in infrastructure in order to get the visibility that you desire.
Understand that every facility is different. And the operations that are taking place in your physical environment will dictate the best approach to layout the zones. If there’s a flow to the way things happen in your environment, you can use that to your advantage. Use the flow to determine where to set‑up the portals, chokepoints and the size of the locations.
Also consider the fact that the size of the physical assets that are being tracked can affect the size of the locations. Depending on what’s being tagged, a good rule of thumb is the larger the RFID tag you put on an item, the better read range you’re going to get.
For example, if you’re tracking large items (ex. ground support equipment or a vehicle) where you can attach a larger tag with a good sized antenna then the locations can be larger. This is because when you seek and locate the item with the mobile handheld, you will be able to achieve much larger read ranges with that larger tag.
For smaller items with smaller tags (ex. tools) be cautious of how large you make those locations. It’s also important to keep in mind how quickly you’ll need to be able to locate the items and the impact to the disruption of your businesses as you’re looking for them.
Using this RFID read zone based approach with fixed readers and passive RFID tags is much more cost effective than using RTLS or active RFID tags. Both RTLS and active tags have their place for very sensitive asset tracking and movement of items throughout certain facilities. But, it is been our experience that there are many scenarios that do not need that level of visibility. We have found that a read zone based asset tracking system using fixed readers in combination with mobile technology to locate a particular item is a really powerful, cost-effective solution.