Issue #166 | Oct. 17, 2008 | by Allen Griebenow
Is it passive or active RFID for IT asset management? Both have their place, depending on what you are trying to do. But perhaps the better question is whether to use passive, active or "micro-wireless."
There is no debate that IT asset management has a real need for an electronic identification capability. IT departments acquire the necessary devices to enable the organization to become more productive and efficient. Once assets arrive, finding and counting them; validating their origin and software composition on-demand; and protecting them from loss and theft is no job for manual processes.
Inventory via “sneaker net” is costly and results are obsolete the next day. Bar-codes as asset IDs are fine, but still manual and provide limited information. Manual efforts to protect assets from theft at doorways are sloppy. Mapping network addresses to physical connections have merit, but more and more wireless equipment is off the grid, and there is no way to protect assets from leaving unauthorized.
So RFID technology today has proven to be a viable, economic way to easily locate, identify, and protect all hard assets. The Passive (without battery) RFID tagging and Active (with battery) RFID tagging are both proven options.
When passive works best
Passive RFID has been effective in addressing short range needs of IT asset management. Tags are easily affixed on or inside the chassis; data written on them can provide information such as the procurement number. Handheld readers can capture information and write updates from a few feet away. Passive RFID adds value and increases productivity for these short range solutions.
Protecting IT assets from loss or theft has serious, legal implications regarding identity theft and intellectual property loss. Fines, public embarrassment and state and federal statutes, such as SARBOX, require this be addressed. Law enforcement data shows the overwhelming majority of theft begins within the organization. For these automated uses, tag reads must be highly reliable.
A number of technology improvements are offered by vendors to address the inability to read passive tags mounted on metal reliably. In the "Metal Mount RFID Tag Benchmark" by Odin Technologies in July, various passive tags were tested in simulated real world environments. “Buyer beware” was the conclusion, as tags were found to work, but not universally.
Tags have been augmented to become more metal tolerant by tuning the exact tag to the exact device, particularly by coupling the antenna to increase performance. This improves transmission reliability, but tuning a diverse group of devices is impractical. With portable assets like laptops that move in all physical orientations, including where a tag on the device ends up in the palm of the hand of a user, tag transmissions are further challenged.
Passive RFID requires a reader antenna at each control point, but dock door readers are not acceptable in office doorway environments. Reader technology has been improved to increase tag read reliability; but the harsh reality is that passive technology has design limitations for use in auto ID applications for asset management when specific location determination and theft protection are prime requirements.
Considering active alternatives
Active RFID has historically had limitations as well. Tags with batteries and electronics are larger than passive tags and by far more costly, ranging from $15 to $75 each. The native reader infrastructure has been acceptable in cost and in form factor as it can be hidden, therefore covert. But unless tags are small enough to be placed on the top of or inside IT assets and unless their cost is reduced to an acceptable ROI, their acceptance is limited. Wi-Fi based active tags, or those that communicate directly to the Wi-Fi network offer the best example of this challenge. To date they have been too large and too costly to be viable for mass adoption.
New active tags operating using sub-network transmissions may now offer the best answer for location and protection solutions. The ability to optimize an ultra small, low cost device, with all the necessary technical elements including a robust, sustainable signal capable of carrying sizeable data, gave birth to the wireless technology area called "micro-wireless." The tags are small enough and cost around $10 each, which easily provides the necessary strong ROI.
Micro-wireless transmission at 433 MHz prevents the clogging of the corporate network, while the receivers seamlessly interface to the network’s enterprise system. The 433 MHz frequency band was set up by the FCC for this type of transmission, as it works best in the business environment. Active tags can be awakened, or “activated,” at control points such as doorways with their transmission less affected by metal and water in the environment because battery power is on-board.
Hybrid tags for supply chain and security
Hybrid active tags, which have both passive and active circuits on-board, are now available providing the comprehensive solution. They are compatible with the supply chain side of asset and inventory tracking, but also provide location determination and theft protection at the doorway. In other words, they take advantage of the short range (near field) design characteristics of passive tags and the long range (far field) design characteristics of active tagging. They also meet the price point at $10 each.
In addition, these hybrids can link the tag to a custodian authorization/access control badge electronically to monitor proper handling. They can also use the battery on board to find a single asset in a pile. This feature, often called “pick-to-light,” has an actual light on the tag that illuminates when specifically queried by an asset number. Only with power on board can pick-to-light work reliably.
While the laws of physics are sometimes difficult to understand, they are even more difficult to change. The designs inherent in RFID technologies dictate their proper uses now more than ever. Passive tagging continues to have a cost advantage and with read/write electronic storage on board, it can be more efficient for property tagging than bar codes. Active RFID is designed specifically for “unattended” applications such as locating, counting and protecting. Happily, the two can co-exist in the same tag.
Allan Griebenow is President and CEO of Axcess International, Inc.
Axcess International Inc. Wireless Intelligence and Business Activity Monitoring
