Are you interested to meet with fellow RFID developers, source out RFID Hardware folks? I recently started a RFID Spotlight Facebook Group with the aim to bring together RFID programmer and hardware providers to share resources and experience. Its just a great way to network and meet people in this field. I made it easy for you to find us, so come and join us by following the link below.

Coming back to the subject of this post. Previously I shared When do we use Real Time Location Systems (RTLS), I will continue to share on the pros and cons of using WIFI based RTLS. We had previously used both Ekahau and Placelab for projects. Although I do not rule out some situations that suggest to us RFID based RTLS system is more superior, in general there are just more tangible benefits to choose WIFI based RTLS systems.

Some benefits of using a WIFI based RTLS are:

1. Depending on the requirements for location granularity, if done properly WIFI based RTLS systems like Ekahau produce high tracking accuracies. Ranging on average between 1 metre - 3 metres indoors.
2. Reuse and leverage on existing WIFI infrastructure. Why spend all that money to invest in a proprietary RFID infrastructure that cannot be reused?
3. Quick ROI for WIFI investments by enabling other location-based applications or wireless applications.
4. With growing categories of devices built-in with WIFI, organizations can also track other assets such as PDAs, mobile phones, laptops and any other WIFI enabled devices. Ekahau client application supports a number of PDA devices.

The cons associated with WIFI based RTLS are :

1. Lack of Scalability : RTLS like EPE requires pre-calibration.In the language of Placelab, it means we need to train the system to “learn” about places on the map in relation to actual real locations. It is fine if you are calibrating for a bunch of classrooms in a small area, however it becomes increasingly complex to calibrate for large spaces - *think* stadium, 30-floors building, airport. EPE has a feature to “merge” calibration data of different maps ( e.g. one map for each floor ) which allows us to distribute that load among a few good persons. However the results from the merged calibrated data often falls short of the required accuracy, in fact occasionally erratic. Packages like Placelab also do not have “merge” capabilities.
2. Location Model. WIFI based RTLS builds a location model ground-up from inputs such as RSSI of any given location. RSSI as you know can be affected by structures, especially solid steel structures and even moving bodies, partitions etc. Several environment issues may potentially affect these variables - access points ( *imagine* a segment of WIFI access points crash out ), structures that block signals, new partitions etc. Particularly in a museum environment, where new exhibitions are frequently replaced every other quarter and new walls/partitions being built, the original location model may be “damaged”. In situations like this, the rule of thumb is to update the calibration model every three to four months.
3. WIFI Power Intensive. This is as plain as vanilla gets. WIFI is a pure power sucker. Its pure wishful thinking that a PDA with WIFI turned on can last more than 3 hours. Bearing in mind the fact, PDA internal battery actually performs poorer over time. It means a new WIFI PDA may last 2 - 3 hour the first time it is used; after several months of continual usage, it may last no more than 1 hour with WIFI turned on.

Well I hope we provided some notes (above) to help make your final decisions on RTLS implementations. Look forward to any form of comments to add to my points…

Share This

This is part 1 of 2 on RTLS. The idea is to give an introductory to RTLS and follow up with the pros and cons of RTLS in relation to an actual implementation.

Since the rise of RFID, everyone has something they want to track. From the big boys in the ranks of Wal-Mart, Metro AG, to small-mid-size inventory based setups, are quickly harvesting every RFID feature to reap its benefits. We have received some enquiries from tagging jewellery (*obviously*) , to producing RFID labels for medical bottles, tracking WIP items on manufacturing floor, to keeping tabs on people/patients real time. So the question is, can “one size” fit all?

Certainly not. RFID comes in several types and each may likely be more suitable for specific applications - (1) Passive based RFID (2) Semi-Passive RFID and (3) Active based RFID. For passive based RFID, they are further sub divided into LF, HF, UHF.

What I hope to share is on the practicality of Active RFID, or the term coined “Real Time Location Systems”. First to explain what it is. Real Time Locations Systems, commonly abbreviated RTLS generally falls into two implementation groups. The first uses RFID technology while the second approach adopts Wireless LAN, specifically what is commonly known as WIFI. It is debatable which technology was first used in RTLS; some say RFID and the other camp claims WIFI.

It was 2002 when we started working on RTLS based projects. Since that time, I have consulted in several projects that make use of RTLS. Our team has also developed several mobile applications using engines such as Ekahau Positioning Engine and Placelab.

Now, there are several options available in the market for RTLS. This is a list of WIFI based RTLS products, and you will notice one on the list is based on open source :

• Ekahau
• AeroScouts
• Radianse
• Pango Networks
• Placelab (open source, active tags not available)
• NIST
• RFIND ( thanks Marilyn!)

At the time of this writing, RTLS systems have also been implemented using Ultrawide Band (UWB) technology. RTLS setup at its basic, consists of a battery operated tag/badge that communicates with readers/beacons strategically placed within a building, park etc. In WIFI based RTLS, the active tag wireless transmits RSSI data to the location engine server on the wireless network. The location engine acts on the Received Signal Strength Indicator (RSSI) information for each device and calculates the coordinates which represent the device’s location on the map.

Not to be confused with passive based RFID, RTLS serves specific usage scenarios which cannot handled well (or efficiently) by HF or UHF RFID systems.

RTLS Use Case : In general RTLS use case will have a specific requirement to track assets or people whose locations are arbitrary at any point of time. For example, in a hospital there is an increasing requirement to track hospital mobile assets such as infusion pumps, beds, wheelchairs. With these assets, there are no associated planned routes that can suggest strategic placements of HF/UHF RFID readers. It is almost impractical to plant RFID interrogators at every corner, on every floor of a facility. Because of the short reading distance of passived based RFID systems, you will need at least one RFID reader every 3 - 5 metres (for HF systems every 1.5 metres) !!

In relation to this, a typical RTLS use case will require the future system in providing very fine granular localized information of its asset. Engines such as those from Ekahau, AeroScouts and NIST can provide tracking average accuracy of mere metres. Walking along corridors, Ekahau Positioning Engine in particular performs localization on average accuracy of one to two metres.

A key deciding factor on using RTLS, as the name implies concerns timing. Active tags being powered by batteries can be programmed to repeatedly send out signals (packets) in very short intervals of time. The location engine consumes these packets calculates the device’s approximate location. Typically active tags is able to “contact” a nearby beacon or access point in distances ranging from 25 metres to 100 metres, depending on the grade of access points used. In stark contrast, passive tags relies fully on RFID readers to power itself. With the uncertainty that a passive tag may be sufficiently close enough to a reader, there is considerably low chances the tag can even be detected to begin with.

In summary a typical RTLS use case will have at least one of the following requirements :

1. No pre-determined path. Need to “find” assets or people who can be anywhere at any point of time.
2. Application needs to track the exact position of an asset or person down to mere metres within the facility
3. The word is real-time. Use case requires real-time monitoring and reporting of the asset or person’s locality, in very short intervals of time (seconds or minutes)
4. Reading distances further than 3 -5 metres on average

Share This

On this post, we will cover RFID basics to help a newcomer gain a flavour of the technology. This is by no means comprehensive, and only aims to serve starters rather than the main dish itself.

RFID Types
RFID is commonly grouped into its operating frequencies.

• Low Frequencies or LF
  RFID devices operate at 125 KHz - 148 KHz. The reading range at this frequency is typically 0.5 inches to 4 inches.
• High Frequencies or HF
  RFID devices operate at 13.56Mhz. The reading range of HF devices typically go from a few inches to several feet. With longer reading distances, HF enables other commonly installed applications such as RFID security gates, library management applications. Singapore National Library Board ( NLB ) uses HF technology for all its library branches.
• Ultra High Frequencies or UHF
  Commerical companies like Intermec and Alien Technology offer devices in this space. UHF devices operate in 915 MHz. UHF devices achieve the furthest reading range of the three. Typically from above 1 metre.

RFID Nemesis
There are several factors, arising from environmental or project requirement, that will degrade the smooth functioning of a RFID setup.

• Metal Effects
  HF Devices suffers serious interface from metallic objects. Metallic objects blocks the path of HF signals, with the effect of degrading or in some circumstances cancel the readability of the devices. LF devices on the other hand works fairly well in both metal and fluid based environments.
• Fluid Effects
  UHF devices cannot negotiate RF signals in the presence of fluids such as the human body. The human body composed mostly fluid cause serious signal interference for UHF devices. To do a simple experiment. Place an UHF tag completely hidden in your palm, and bring the UHF tag completed enclosed in your palm close to a reader-antenna. The result is, the tag remains undetected even at close range.

Standards
International Standards defines a framework for interoperability between manufacturers of tags, readers and antenna. This creates a platform that allows different vendors to create hardware and software products to work with each other by adhering to operating standards. Again, the list is by no means comprehensive but aims only give you a flavour of the existing commonly applied standards in the RFID world.

EPCGlobal is a non-profit group that is leading the overall industry to develop standards for the use Electronic Product Code ( EPC ) in RFID. They are instrumental in driving the RFID Gen(eration) 2 specification and getting a slew of vendors to roll out products based on the new specifications. The RFID Gen 2 is submitted to the ISO standards committee.

ISO 15693 defines the ISO standard for devices operating in the 13.56 MHz frequency.

ISO 11784 & ISO 11785 defines the standards that regulate RFID usage for animals. While ISO 11784 defines the data structure of the identification code, ISO 11785 specifies the protocol aspects for the transponderd, data transmission requirements between the transponder and the transceiver.

RFID Gen 2 defines a specification that combines RFID technology, the Internet and Electronic Product Codes to provide a highly efficient information delivery throughout supply chains.

RFID Middleware
RFID Middleware is a software platform that manages RFID data. The middleware software layer filters RFID data from RFID Readers, and routes the data to a multitude of enterprise systems within the business. A significant component common with providers of RFID middleware software is the RFID device management. This layer of software negotiates events triggered by new RFID data detected at the RFID reader device level. New RFID data is subsequently filtered and translated to business related events and sent to the respective systems for appropriate response.

RFID Integration
RFID integration stems from the need for organizations to incoporate RFID technology into existing hardware and software infrastructure. Almost all the time, phase-in approach to RFID adoption is preferred in order to control the costs and risks of the investment. There is a certain amount of complexity involved in RFID integration. For sizeable projects, this will include the integration of the RFID middleware software that provides a platform for scalability.

For example, existing software process will have a built-in procedure to issuing unique identification codes for current inventory. By what means, can additional software be structured to seamlessly incoporate RFID to existing systems? Bearing in mind the freshly integrated RFID component should not disrupt the existing operations flow.

Share This

I found this this online video recorded by Intermec Education Services, on google the other day. It has good video content that describes companies that have successfully implemented RFID for their supply chain management and warehousing operations.

Watch Video here

Share This

As a RFID solution provider, one of the first things we do is to understand what customers like RFID do for their business. The final outcome of the design rest on several variables such as the tracking velocity requirements, reading distances, tag sizes, antenna size, frequency of monitoring, the volatile environment. Often there are some tradeoffs between them, depending on the project requirements.

To illustrate an example of tradeoff, I will share on a common requirement I hear often. In the jewelry industry context, the RFID tags have to be very small. Understandably, the aesthetic features of the displays are the keys to healthy store sales. Absolutely nothing must obstruct or disrupt the view jewellery in all its “glaring” beauty. Most people only SIN when they look at the object of their desire long enough, or should I say lust. Haven’t you realized jewelry stores always install spot lights? Its like a hypnosis going on in there Anyway, to satisfy that requirement, the choice of tag sizes are retricted to 15mm x 32mm or 30mm (diameter types), small enough to tuck the tag into the jewellery holder or under a flap. The tradeoff is at those sizes the antenna read distance strinks to between 5cm - 15cm depending on the effects of attentuation. Usually this is not a problem if the requirement is only to optimize inventory. However in order to maximize IT investment, store owners like to have RFID lookout for possible thefts, via RFID Gate Antennas. With that read distance, it is not going to happen. The good news is there are more than one solutions to most problems. Our team had designed a jewellery software system that aims to prevent thefts at the operations level, way before anyone gets a chance to snatch a jewelry piece and make a dash for it. Come on guys, it will be too late by then. And if they are seriously comtemplating on robbery, they will come with their grenades, M16, GPMGs! No system in the world can save your jewelry, we have the cops for that.

Share This

As the title describes, this post is about RFID tag orientation. As trivial as it sounds for those who are RFID experts, this is the first lesson for all who freshly stumble onto this part of the wireless world. So before I continue, welcome! Now as far as the rule goes, just because the darn reader is not responding it does not mean the tag does not exist! Of course you know that, what am I thinking?!. Often the newbie struggles to explain the mystery of disappearing tags or so it seems. What I mean is, at most positions the RFID tag can be picked up by the reader fairly nicely. However when the tag is oriented a certain way (even just above the antenna), there is a dead silence from the reader. No, this is not a case of a The Twlight Zone.

EXPLAINATION : Tags receives power by magnetic coupling and receives maximum power at the best orientation. For maximum power induction, the magnetic field lines radiated by the reader antenna must be perpenticular to the RFID tag. In practise the tag can be rotated about 40 degrees either side of its optimal position and will still be read. However if the tag is placed parrallel to the magnetic lines, the waves are simply skimming on the surface of the tag and will not power it. In the video demonstration, it is using the Single Loop Single Panel configuration. There are several configurations such as Figure-8 Single Panel; as the name implies, the magetic waves flow in a Figure of 8 shape.

The diagram above illustrates the Single Loop Field Radiation pattern created from a single panel. The RFID tag is best positioned when

• RFID tag is closest to the radiating antenna, and
• RFID tag is interrogated right angle to the magentic lines passing through it

At the this optimal position, the RFID tag receives the maximum number of the magentic lines and receives maximum electrical induction. In the design of the RFID jewelry smart shelf for example, all possible orientations of the tag are considered during the design phase. For that we customize antennas for all shapes and sizes to effectively induce the RFID tags at varying orientations.

Share This

John Shoemaker a noted RFID entrepreneur commented on the following about RFID customization solutions,

“This is not going to be an area where you just license some software — there has to be integration and collaboration”

“Vendors really are going to have look at requirements and structure software plans that address those requirements. It’s not a case for canned software,“.

For more, read the article The Failure of RFID.

I have been talking with our partners, and they all have this alikeness about RFID Solutions ~ “What are the standard RFID solutions packages to introduce to clients?”. Unfortunately RFID solutions rollouts take alot more than clicking the INSTALL button. Likely there will be existing software to talk to, defining data exchange protocols, cross platform integration issues, middleware issues etc.

In addition, the deployment environment may pose some challenges in a RFID rollout. If you forget everything else just remember what I am going to say now because it will save you from frustration while you are trying to figure “WHAT THE HELL WENT WRONG??”. Iron, steel and ALL ferrous metal attenuate RF fields. See below for 2 common stumbling blocks …

• On placing the antenna at a particular table, there are problems getting accurate readings. Why? TIP : Look under the table. If the table frame is made out of metal bar forming a closed loop, it is a deathstar to your setup. The close loop actually behaves like a bigger antenna that couple the RF signals.
• After connecting the antenna to the reader, and the reader to the computer via the serial where do you place the antenna? Usually… next the box itself while staring at the screen for some readings. What happens next is a total failure. What had happened? The JINX of RFID must surely be metal materials. In this case, the metal case had blocked out all the forward/return path of the flux lines resulting in total RFID reads failure.

There are probably a dozen other things on the subject of RFID rollouts. The point is, RFID solutions require more detailed design and planning to make the money worth.

Share This

We have been talking to our customers as early as 2002 on implementing RFID based jewelry software management systems. We believe RFID can profoundly improve the efficiency of the jewelry business, that we have seen happen for some. The initial resistance to RFID adoption is not very different from what we hear now. Of course when they experienced 70% savings in costs relating to manpower costs, barriers to theft and other tangible benefits of having such a system, the stories changed inevitably.

I like to touch on one of the MAIN sound of resistance :

RFID is expensive, considering the equipment and tags investment. - TRUE? False.

1. In the case of Advago Jewellery, we partnered a software integrator sometime in 2003 to customize a RFID based solution. Previously Advago had employed more than 7 persons for inventory management, processing and handling transactions and among other manual tasks. Their operations personnel usually spent up to 2 to 3 days to account for all the inventory. When the RFID based solution was rolled out, the inventory process reduced for the company almost 70% of the time they would have taken before to complete the tasks.
2. Another key benefit : The RFID based solution opens up the entire supply chain for detailed scrutiny of which every jewelry item is tracked, yes even its location. At Advago, in one particular instance, loses arising from potential thefts were uncovered ahead of time by an automated detailed audit trail. Of course the management on discovering the loophole scrambled to put in extra checks.
3. Finally about the costs of the tags. Each tag costs about 1% and even less the retail value of each jewelry product in most cases. Amortize that tag cost over the many lifetimes of many jewelry pieces by tag reuse, you will see it further drives the overall costs lower. Compared to the capabilities that RFID enabled for a jewelry business, the costs-benefits are simply overweighing on benefits. In addition, we have observed the costs of RFID tags have steadily fall due largely to more efficient processes that manufacture them.

There are a few other common objections I hear, which I may cover in future posts. But I think I will stop here for now…

Share This