Abstract:
Methods and systems are provided for determining the location of an RFID reader within an environment having a plurality of RFID tags located therein. One method includes activating a tag via an RFID reader and receiving data from an RFID tag. The method also includes transmitting the data from the reader to an access port and determining the location of the reader based on the data. A system includes an RFID tag configured to transmit data when activated by an RFID reader. Furthermore, the system includes an access port configured to receive the data from the reader and a module configured to receive the data and determine the location of the reader based on the data. One RFID reader includes means for activating an RFID tag including data identifying a location of the tag, means for receiving the data, and means for transmitting the data to an access port.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates generally to radio frequency identification (RFID) systems, wireless local area networks (WLANs), and other such networks incorporating RF tags, and, more particularly, to methods of determining the location of an RFID reader within a building or other site. 
       BACKGROUND 
       [0002]    In recent years, Radio frequency identification (RFID) systems have achieved wide popularity in a number of applications, as they provide a cost-effective way to track the location of a large number of assets in real time. In large-scale application such as warehouses, retail spaces, and the like, many types of tags may exist in the environment (or “site”). Likewise, multiple types of readers, such as RFID readers, active tag readers, 802.11 tag readers, Zigbee tag readers, etc., are typically distributed throughout the space in the form of entryway readers, conveyer-belt readers, mobile readers, etc., and may be linked by network controller switches and the like. While it is common for RFID tags to be distributed throughout a commercial space to track assets, the tags have not been deployed in a way that would assist in tracking an RFID reader within the environment. 
         [0003]    Accordingly, it is desirable to provide improved methods and systems for determining the location of an RFID reader in environments where multiple tags have been deployed. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background. 
       BRIEF SUMMARY 
       [0004]    The present invention provides systems and methods for determining the location of an RFID reader within a site having a plurality of RFID tags located therein. One embodiment of the method includes activating a first RFID tag via the RFID reader and receiving, via the RFID reader, first data from the first RFID tag. The method further includes transmitting the first data from the RFID reader to a first wireless access port and determining the location of the RFID reader based on the first data. 
         [0005]    A system in accordance with one embodiment includes a first RFID tag located within the site, wherein the first RFID tag is configured to transmit first data when activated by the RFID reader. The system further includes a first access port configured to receive the first data from the RFID reader and a module in communication with the first access port, wherein the module is configured to determine the location of the RFID reader based on the first data. 
         [0006]    An RFID reader according to various embodiments comprises means for activating a first RFID tag, wherein the first RFID tag includes first data identifying a location of the first RFID tag. The RFID reader further comprises means for receiving the first data from the first RFID tag and means for transmitting the first data to a first access port. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    A more complete understanding of the present invention may be derived by referring to the detailed description and claims when considered in conjunction with the following figures, wherein like reference numbers refer to similar elements throughout the figures. 
           [0008]      FIG. 1  is a conceptual overview of a system for locating an RFID reader in accordance with an exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0009]    The following detailed description is merely exemplary in nature and is not intended to limit the range of possible embodiments and applications. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. 
         [0010]    For simplicity and clarity of illustration, the drawing figures depict the general structure and/or manner of construction of the various embodiments. Descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring other features. Elements in the drawings figures are not necessarily drawn to scale: the dimensions of some features may be exaggerated relative to other elements to assist improve understanding of the example embodiments. 
         [0011]    Terms of enumeration such as “first,” “second,” “third,” and the like may be used for distinguishing between similar elements and not necessarily for describing a particular spatial or chronological order. These terms, so used, are interchangeable under appropriate circumstances. The embodiments of the invention described herein are, for example, capable of use in sequences other than those illustrated or otherwise described herein. Unless expressly stated otherwise, “connected” means that one element/node/feature is directly joined to (or directly communicates with) another element/node/feature, and not necessarily mechanically. Likewise, unless expressly stated otherwise, “coupled” means that one element/node/feature is directly or indirectly joined to (or directly or indirectly communicates with) another element/node/feature, and not necessarily mechanically. 
         [0012]    The terms “comprise,” “include,” “have” and any variations thereof are used synonymously to denote non-exclusive inclusion. The terms “left,” right,” “in,” “out,” “front,” “back,” “up,” “down,” and other such directional terms are used to describe relative positions, not necessarily absolute positions in space. The term “exemplary” is used in the sense of “example,” rather than “ideal.” 
         [0013]    For the sake of brevity, conventional techniques related to signal processing, data transmission, signaling, network control, the 802.11 family of specifications, wireless networks, RFID systems and specifications, and other functional aspects of the system (and the individual operating components of the system) may not be described in detail herein. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent example functional relationships and/or physical couplings between the various elements. Many alternative or additional functional relationships or physical connections may be present in a practical embodiment. 
         [0014]    The present invention generally relates to systems and methods for locating an RFID reader. Specifically, the systems and methods locate an RFID reader in a building or other site where RFID tags have previously been deployed. 
         [0015]    Referring now to  FIG. 1 , an example environment  102  useful in describing the present invention generally includes a building or other site (alternatively referred to as an “environment”). Note that while a three-dimensional, multi-floored building is illustrated in  FIG. 1 , the invention is not so limited. That is, environment  102  may be any two-dimensional or three-dimensional space within or without a building and other structure. Example environments include, for example, single-story buildings, multi-story buildings, school campuses, commercial buildings, warehouses, and the like structures. 
         [0016]    A number of RF tags (“RFID tags,” or simply “tags”)  104  are distributed throughout environment  102 . In general, these tags  104  are preferably pre-deployed throughout environment  102  either during or after construction. 
         [0017]    In general, as described in further detail below, a system  100  includes an RFID reader  110  that suitably activates any nearby tags  104  and sends the relevant tag data to one or more access ports (APs)  120  and wireless switches  130  located remotely from RFID reader  110 . Various software and hardware (e.g., computer  150 , etc.) produce a display  160  indicative of the position of RFID reader  110  within environment  102 . 
         [0018]    Tags  104  may be positioned throughout environment  102  with a density and number that is appropriate given the power of the tags as well as structural details (e.g., internal architecture) of environment  102 . That is, tags  104  may be distributed evenly throughout the site, or may be clustered in predefined “zones.” In the illustrated embodiment, for example, zones  105  are defined for each floor  105 , as well as for an elevator bank  103 . As shown, multiple tags  104  are included in each zone. In general, each zone preferably has at least one such tag  104 , but may have any number, depending upon the size of the zone and other such factors. 
         [0019]    Tags  104  may be one or more of various types of tags. Examples of tags  104  include, but are not limited to, active tags, passive tags, semi-active tags, WiFi tags, 801.11 tags, and the like RFID tags. Note that the term “RFID” is not meant to limit the invention to any particular type of tag. That is, the term “tag” refers, in general, to any RF element that can be communicated with and has an ID (or “ID signal”) that can be read by another component. In general, RFID tags (sometimes referred to as “transponders”) may be classified as either an active tag, a passive tag, or a semi-active tag. Active tags are devices that incorporate some form of power source (e.g., batteries, capacitors, or the like) and are typically always “on,” while passive tags are tags that are exclusively energized via an RF energy source received from a nearby antenna. Semi-active tags are tags with their own power source, but which are in a standby or inactive mode until they receive a signal from an external RFID reader, whereupon they “wake up” and operate for a time just as though they were active tags. While active tags are more powerful, and exhibit a greater range than passive tags, they also have a shorter lifetime and are significantly more expensive. Such tags are well known in the art, and need not be described in detail herein. 
         [0020]    Furthermore, each tag  104  includes data (e.g., a tag ID, coordinates, etc.) that can be read by RFID reader  110 , which data is also stored in a base station  140  (e.g., control center, etc.) and is used to assist in locating RFID reader  110 . During operation, each tag  104  is read by RFID reader  110  when RFID reader  110  is within a range (e.g., about 0 meters to about 10 meters), which range varies depending on the RFID reader and RFID tag technology used. The data transmitted from each tag  104  is read by RFID reader  110  and transmitted to an RF switch (discussed below). The data transmitted from tag  104 , via RFID reader  110 , can then be used to determine the approximate location of RFID reader  110 . 
         [0021]    RFID reader  110  may have multiple associated antennas, and may incorporate additional functionality, such as filtering, cyclic-redundancy checks (CRC), and tag writing, as is known in the art. Each antenna within RFID reader  110  has an associated RF range (or “read point”), which depends upon, among other things, the strength of the respective antenna. The read point corresponds to the area around the antenna in which a tag  104  may be read by that antenna, and may be defined by a variety of shapes, depending upon the nature of the antenna. It is not uncommon for RF ranges or read points to overlap in real-world applications (e.g., doorways, small rooms, etc.). 
         [0022]    Switching device  130  (alternatively referred to as an “RF switch,” “WS,” or simply “switch”) may be coupled to a network  135  (e.g., a WiFi network coupled to one or more other networks or devices) and communicate with one or more software applications (not shown). Wireless access ports  120  (alternatively referred to as “access ports” or “APs”) are configured to wirelessly communicate with RFID reader  110 . Access ports  120  suitably communicate with switch  130  via appropriate communication lines (e.g., conventional Ethernet lines, or the like). Any number of additional and/or intervening switches, routers, servers and other network components may also be present in system  100 . 
         [0023]    A particular AP  120  may communicate with multiple RFID readers  110  (e.g., when multiple RFID readers  110  are located within environment  102 ). One or more APs  120  may be coupled to a single switching device  130 , as illustrated, and may be distributed in any advantageous manner to a central office (not shown) located internal to or external to environment  102 . 
         [0024]    In general, RF Switch  130  determines the destination of the packets it receives and routes those packets to the appropriate AP  120 . Thus, each AP  120  acts primarily as a conduit, sending/receiving RF transmissions via RF switches  130 , and sending/receiving packets via a network protocol with WS  130 . 
         [0025]    Switch  130  may support any number of tags that use wireless data communication protocols, techniques, or methodologies, including, without limitation: RF; IrDA (infrared); Bluetooth; ZigBee (and other variants of the IEEE 802.15 protocol); IEEE 802.11 (any variation); IEEE 802.16 (WiMAX or any other variation); Direct Sequence Spread Spectrum; Frequency Hopping Spread Spectrum; cellular/wireless/cordless telecommunication protocols; wireless home network communication protocols; paging network protocols; magnetic induction; satellite data communication protocols; wireless hospital or health care facility network protocols such as those operating in the WMTS bands; GPRS; and proprietary wireless data communication protocols such as variants of Wireless USB. As described in further detail below, switch  130  includes hardware, software, and/or firmware capable of carrying out the functions described herein. Thus, switch  130  may comprise one or more processors accompanied by storage units, displays, input/output devices, an operating system, database management software, networking software, and the like. Such systems are well known in the art, and need not be described in detail. Switch  130  may be configured as a general purpose computer, a network switch, or any other such network host. In a preferred embodiment, switch  130  is modeled on a network switch architecture but includes RF network controller software (or “module”) whose capabilities include, among other things, the ability to allow it to configure and monitor RFID reader  110  and its antenna(s). 
         [0026]    Locationing of RFID reader  110  generally involves examining all of the data received from one or more RFID tags  104  at a particular time, and then using rules and a locationing algorithm to determine the most likely location of the RFID reader  110  based on the received tag data. As discussed above, the data for each RFID tag  104  is stored in base station  140  and system  100  is configured to reconcile the location of RFID reader  110  based on the tag data. Specifically, system  100  is configured to reconcile the location of an RFID reader  110  on a pre-defined floor map (i.e., a map of the location of RFID tags  104 ) and/or a zone map, and may also be configured produce a graphical representation identifying the position of RFID reader  110  within environment  102 . Any such map and/or zone information may be preloaded, downloaded over network  135 , or received from environment  102 . Stated another way, the ID for each tag  104 , and their respective locations, are preferably known prior to beginning the locationing process; however, this knowledge may be distributed over a number of systems and networks. In a particular embodiment, the placement of each RFID tag  104  is predefined, and nomenclature related to that placement is embedded within each RFID tag  104  (and saved in base station  140 ) so that a quick understanding of the location of the RFID tag  104  in relation to the floor and/or zone can be determined without the use of drawings. 
         [0027]    The following example may be useful in understanding the operation of system  100 , wherein RFID reader  110  is a WiFi-enabled laptop computer, a cellular telephone, a PDA, a Palm®, or other similar device. Here, as RFID reader  110  is transported (e.g., by a conveyor belt, a person, a motor vehicle, etc.) through environment  102 , RFID reader  110  reads data from each RFID tag  104  that RFID reader  110  comes within range of. RFID reader  110  then transmits the tag data (via RF switch  130  and AP  120 ) to computer  150  and is represented on display  160 . That is, the location of RFID reader  110  may be known in real-time as RFID reader  110  is transported through environment  102 . 
         [0028]    In another example where environment  102  is a warehouse, RFID reader  110  may be integrated within a forklift to determine and track the location of the forklift as it navigates through the warehouse. That is, as computer  160  receives the location data that RFID reader  110  has read from one or more of tags  104 , the path(s) that the forklift traveled over a given period of time may be determined and saved by computer  150 . 
         [0029]    It should be appreciated that the example embodiment or embodiments described herein are not intended to limit the scope, applicability, or configuration of the invention in any way. For example, these methods may be used in connection with standard barcode readers and the like. In general, the foregoing detailed description and examples will provide those skilled in the art with a convenient road map for implementing the described embodiment or embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the invention as set forth in the appended claims and the legal equivalents thereof.