Passive RFID providing RTLS - Real or hype

This week's blog comes to us from ODIN's own mythbuster  Adam "The Source" Bennett one of the RFID industry's top engineers:

Investments made over the last three years in RFID are starting to reap great value today for end users. Last year, new passive RFID technology companies with the capability to provide real time location system (RTLS) relying upon passive Gen 2 EPC tags emerged:  Mojix and RF Controls.  According their marketing claims, these "revolutionary" technologies are able to see and locate standard inexpensive passive tags at a resolution once only possible with active tags that are up to 500x more expensive.  So, do these two solutions work? 

 

New RFID technology inevitably arrives wrapped in marketing hype.  End users have put their trust in ODIN since 2002 as a useful evaluator, able to cut through the hype and provide an independent view. Our clients requested that we assess these competing systems in our HQ RFID laboratory, so over the last couple of months we evaluated both companies. One thing is clear, they are both similar to readers in that they are only one ingredient of an RFID solution.

 

In simplest terms, Mojix's isolates the transmitter from the receiver by distributing a network of transmitters to cover a large area and controls the system with an ultrasensitive receiver.  The "Star" is the receiver and brains.  "eNodes" are the transmitters that must be positioned wherever you wish to create an interrogation zone.  The company claims one Star is able to "hear" tags over 600 feet away and cover an area up to 250,000 sq feet.  Using the eLocation feature, the company claims the system can locate tags within three feet.

 

RF Controls takes a different approach.  They employ a sophisticated phased array antenna that allows them to point a narrow beam of RF energy in a specific direction.  This Intelligent Tracking and Control System (ITCS) enables them to scan across an area, activate and read tags at a greater distance than a reader with a normal RFID antenna.  Using two of the phased array antennas allows triangulation of the tag location in three dimensions.  The company claims two panels are able to locate tags as precisely as within 1.5 feet across an area 60 feet wide.

There is also a third approach apparently being developed by the Boston-based company Reva however details are not easy to attain. With more than $52 million of venture capital investment it is sure to be a formidable competitor in the passive RTLS space.

While the Mojix Star is highly sensitive and able to "hear" tags at great distances (we confirmed almost 200 feet), the Achilles system's heel is needing an eNode antenna at a close distance (claimed up to 30 feet, ideally within 15 feet) to guarantee that the tags will activate.  In this respect, Mojix's technology is only slightly different from installing a large number of standard RFID readers to saturate an area with RF energy, except each eNode is cheaper and easier to install. So yes the technology works, but tags aren't really reading at 600 feet.

While RF Controls ITCS beams were able to activate and read tags at comparatively long distances (we confirmed at least to 75 feet), the time it takes for two antenna panels to effectively scan a 2,000 square foot area can last up to a minute and the beam must have relatively clear line-of-site, so fast moving items would be problematic.  Location accuracy was about 1.5 feet under ideal circumstances, but error increases at the scan edges, when only one antenna is able to see a tag, or when obstructions are introduced.  RF Controls recommends tags with Higg-3 or Monza-3 chips for best results.

So, which technology is better?  The value of each technology will depend upon the use case balanced by costs driving your ROI.  No single RFID technology solves all needs and each of these solutions includes practical limits that must be considered.  The ODIN team is impressed with the abilities of both technologies and would be happy to provide guidance on which component should be leveraged to create your optimal solution.Clearly as more feedback from end-users come in and more R&D goes into these projects we would expect great improvements in 2010 and 2011.

 

The ODIN team is working with clients now to develop pre-packaged solutions later in 2009 around these new passive RTLS systems. Innovations like these will continue to drive more and more value in the RFID industry.