Embodiments of the present invention generally relate to Radio Frequency Identification (RFID) applications. More specifically, embodiments of the present invention relate to techniques for real-time and offline location tracking using passive RFID technologies.
Radio Frequency Identification (RFID) is an automatic identification method which relies on the storing and remotely retrieving of data using devices, such as RFID tags or transponders. RFID tags or transponders are also known as proximity, proxy, or contactless cards, because data from an RFID tag can be retrieved without physical contact. Generally, a device, such as an RFID reader, uses radio waves to remotely retrieve a unique identifier stored using the RFID tag when the RFID tag is within proximity of the RFID reader. RFID tags can be attached to or incorporated into a product, animal, or person for the purpose of identification by the RFID reader. RFID readers can be placed on doorways, in train cars, over freeways, mounted on vehicles, and also can be embodied in mobile handheld devices.
RFID technologies have been traditionally implemented in different ways by different manufacturers, although global standards are being developed. Thus, computer applications using RFID are also typically hard-coded to specific RFID devices sold by the same manufacture. One problem with this arrangement is that the computer applications are limited to using only the data retrieved from the specific RFID readers.
In order to provide automated shipping and receiving, real-time inventory, automated shipping and received, and real-time security, other types of RFID sensor devices, such as environment sensors (e.g., temperature and humidity sensors), location sensors (e.g., Global Positioning System or GPS devices), and notification devices, may be required. For example, one cold chain solution provides an RFID tag embedded with a temperature sensor. Cold chain refers to a temperature-controlled supply chain. An unbroken cold chain is an uninterrupted series of storage and distribution activities which maintain a given temperature range.
However, one problem with embedding sensors with RFID tags is that the increase in cost and complexity associated with each RFID tag. Furthermore, if computer applications are tied directly to specific RFID readers, the only items for which sensor data can be used from those applications are those that can be tagged and directly sensed using the specific RFID readers.
Accordingly, what is desired are improved methods and apparatus for solving the problems discussed above, while reducing the drawbacks discussed above.