Active radio frequency identification (RFID) tags are now commonly being used to track and locate valuable assets in the healthcare, manufacturing and logistics markets. Quite different from the Passive RFID solutions famously championed by Wal-Mart and others, Active RFID systems are integrated into critical business processes to improve operational efficiency and reduce costs by providing real-time location information about assets and even people. While Passive RFID has held the limelight in the past, Active RFID solutions have in fact been quietly saving millions of dollars for enterprises around the world.
This guide introduces Active RFID with a special focus on the tags themselves, outlining common deployments, defining the competing methods of tag-to-network communication and explaining how to choose the right Active RFID tag to meet your needs.
Unlike their Passive counterparts, Active tags are sophisticated wireless devices, capable of communicating data at long range and operating in rugged environments for years at a time.
Active tags do differ in price, with a wide range available, but unlike Passive tags, price is not the distinguishing factor. Instead, organizations must consider a wide range of attributes and technological factors when selecting the correct configuration.
This guide will help you locate the correct Active tag solution to fit your company's needs.
To start with, a few definitions:
- RFID — Radio frequency identification uses electromagnetic or electrostatic signals to uniquely distinguish and identify a unique mobile "tag" device. Assets can be tracked if the identity of the attached tag is known.
- Active RFID — An identification system in which tags have their own power source (usually a battery), enabling them to broadcast an identifying signal. This extends the range of the tags and the capability for communicating advanced information such as location.
- Passive RFID — An identification system in which the tags are not powered, but rather rely on active signals from the location transmitters for their response. This limits the range of the tags to a few feet.
- RSSI — Received signal strength indication is an algorithm that determines the location of an active tag by measuring the power of radio signals. RSSI typically works best for indoor deployments where the density of active RFID or Wi-Fi readers is high.
- TDOA — Time difference of arrival is an algorithm that determines the location of an active tag through triangulation, measuring the time differences of a single signal received by multiple receivers. TDOA typically works best in outdoor environments or large open indoor environments (e.g. large manufacturing hangars).
Sample uses of active RFID tags include tracking infusion pumps throughout a hospital so that nursing staff and biomedical teams can find them in a timely manner; tracking high-value work in process (WIP) inventory in the aerospace and automotive manufacturing sectors; and tracking trailers and containers in the transportation/logistics industry, both inside a warehouse and around the depot.
Once you have made the decision that Active RFID fits your asset tracking needs, there are a wide variety of technologies, possibilities and options to consider. Most active RFID systems are sold as complete solutions, with tags, readers (if necessary) and software.
Key Factors to Consider
- Standards-based or proprietary?
- Network Support
- Tracking and location capabilities
Determining your need for location information is a critical step, and will help narrow the list of potential tag vendors. In addition, you should also think about the need for potential future deployments, and choose a vendor that can be flexible enough to address your needs now, and in the future.
- Batteries: bigger isn't always better
In order to make a fair comparison, make sure you understand the size and cost of the batteries being proposed, not just the maximum battery life listed on the product data sheet. Ideally you should look for a combination of small battery form factor with low power consumption, which will give a compact, long-life tag.