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Understanding Your Asset-Tracking Options

Each type of location-tracking technology has its own benefits and drawbacks. Here's an overview of what you should consider.
By Martyn Mallick and Matt Teskey
Technology Options
The charts below provide an overview of various technologies used today for asset location tracking. Each provides a summary of the technology, discusses some benefits and drawbacks, highlights use cases for which the technology is suited and currently being utilized, and provides a small sampling of hardware vendors to contact for more details regarding specific implementations.

GPS (Global Positioning System)
Summary GPS uses satellites and receivers to calculate the latitude, longitude and altitude of the receiver. GPS receivers are often embedded into mobile devices, including PDAs or dedicated GPS devices, to provide on-device logic and mapping/location feedback to the user.
Benefits Technology maintained by United States Department of Defense; enterprises need to invest only in receivers, and do not have to create or maintain reader infrastructure.
Drawbacks Reported location and actual location often differ by 8 to 10 meters; not suitable for indoor applications.
Common Uses Military applications; consumer driving direction applications; exploration; equipment location tracking; stockyard asset management.
Hardware Vendors Pharos, Identec Solutions, Garmin
Wi-Fi Real-Time Location Systems (RTLS)
Summary Wi-Fi RTLS offerings use a Wi-Fi network and combination of calibration and software algorithms to provide X,Y positions to certain Wi-Fi devices and custom Wi-Fi active RFID tags from the vendor.
Benefits Leverage existing Wi-Fi infrastructure; generate real-time X,Y data; tunable to balance performance with battery life.
Drawbacks Increasing the preciseness of the location data requires more Wi-Fi access points; Wi-Fi does not function as well outdoors, because there are fewer objects off of which wireless signals can reflect; the cost of Wi-Fi tags can be prohibitive, or the form factor inappropriate for certain asset types.
Common Uses Tracking equipment and staff in hospitals; warehouse applications tracking forklifts, equipment and assets.
Hardware Vendors Ekahau, AeroScout
Active RFID
Summary Active RFID systems use battery-powered tags and specialized hardware/communications to provide visibility data, but typically not with X,Y granularity. Some solutions also incorporate environmental sensors in tags for environmental context.
Benefits Flexible hardware configurations enable performance over wide distances with options for room-level granularity; tunable to balance performance with battery life; does not require Wi-Fi infrastructure; often provides the ability to incorporate other sensor data (temperature, light and so forth), along with location data.
Drawbacks Technology tends to be proprietary in nature; cost can fluctuate greatly based on features and vendor.
Common Uses Tracking specialized equipment in hospitals, cold chain or related applications where both location and related sensory data is required.
Hardware Vendors Axcess, Identec Solutions, RFCode
UWB (Ultra Wideband)
Summary UWB systems transmit data across a broad range of radio frequencies using proprietary hardware (readers, sensors and battery-powered tags) and communication protocols, plus calibration and software to provide X,Y position data. Setting up a system involves placement of readers or reference tags at certain locations, calibrating the system and registering active UWB RFID tags.
Benefits Does not require Wi-Fi infrastructure; some offerings are very rugged and suitable for outdoors; tunable to balance performance with battery life; very accurate location precision.
Drawbacks Relatively new technology; not as proven as alternatives.
Common Uses Market is not completely defined, but ideal for applications where high level of location accuracy is necessary.
Hardware Vendors Ubisense, Multispectral Solutions
Passive RFID
Summary Associates fixed X,Y coordinates with passive RFID readers/antennas. When an antenna reads a tag, it associates the X,Y of the antenna with the tag at that specific point in time. Use sensors or multiple read points for directionality of movement.
Benefits Leverage existing RFID investments/knowledge; flexible hardware choices; low-cost tags.
Drawbacks Provides only choke-point-level visibility of assets at distinct read points; no visibility of assets between read points.
Common Uses Event attendee tracking; location tracking of lower-value assets; recording of checkpoints.
Hardware Vendors Motorola, Intermec, ThingMagic, AWID, Alien, Sirit
Mobile RFID/Bar Code—
with RTLS Tag or Wi-Fi on Device
Summary Use an RTLS system to track the location of a handheld/forklift passive RFID reader. Any reads of RFID tags (active or passive) or bar codes by the reader are associated with the X,Y position of the reader (from the RTLS system) at the specific time the tag read or bar-code scan occurred.
Benefits Higher-cost RTLS tags are used only on forklifts, so lower-cost tags or bar codes can be used on assets; leverage existing RFID tag or bar-code investments.
Drawbacks No real-time visibility if the asset being tracked with an RFID tag or bar code is being moved in conjunction with a forklift or handheld that lacks an RTLS tag.
Common Uses Inventory applications; warehouse management; stocking/picking applications.
Hardware Vendors Motorola, LXE, Intermec, Psion Teklogix
Mobile RFID/Bar Code—
with Reference Tags
Summary Place fixed RFID tags (active or passive) around the location to be monitored (for example, spaced out on warehouse floor, affixed to shelves and so forth) and associate a fixed X,Y position with each fixed reference tag. When a handheld/forklift RFID reader reads a reference tag, the X,Y of the reference tag is used as the X,Y for the reader, and any asset tags read or bar codes scanned by the reader before the next reference tag is read.
Benefits Low-cost reference tags used to cover location; variety of RFID tag form factors for indoor/outdoor/rugged applications; leverage existing RFID tag or bar-code investments.
Drawbacks No visibility of mobile reader between reference read points; no real-time visibility of asset movement if a forklift or handheld without an RTLS tag is used when moving assets. A higher quantity of reference tags and associated calibration tasks is needed for greater location granularity.
Common Uses Warehouse applications, stocking/picking applications.
Hardware Vendors Motorola, LXE, Intermec, Psion Teklogix

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