Abstract:
A system, techniques, and apparatus for detecting rogue RFID readers are disclosed. The system detects unauthorized reader to tag communication, and with multiple detectors, provides location information concerning one or more unauthorized readers. The system can detect high power commands of an unauthorized reader(s) in predefined areas and be integrated with an article surveillance system.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure relates to radio frequency identification (RFID) technology, and more particularly to detecting rogue RFID readers and writers. 
       BACKGROUND 
       [0002]    Radio frequency identification (RFID) implementations have become very useful for electronic asset management and security in modern business. Implementations are based on electronic interaction between REID tags and RFID readers. 
         [0003]    RFID tags are electronic devices attached to physical objects containing information related to the object. RFID readers communicate with tags through one or more antennas to collect information about the presence, identification and location of items such as inventory items, personal or business assets. 
         [0004]    RFID readers can have a relatively short or long range of operation depending on their operating frequency, transmitter power level and specific application requirement. A reader may work as a stand-alone instrument or as part of a RFID reader network. RFID reader networks are often capable of simultaneously reading multiple RFID tags, registering and monitoring the status of tagged items, and reporting possible malfunctioning, disappearance, or unauthorized movement of objects. 
         [0005]    Although benefits of RFID implementations are apparent, several problems can arise with their use. For example, in areas with public access, RFID tags can be compromised by individuals using an unauthorized reader, hereinafter referred to as a rogue reader, which can issue commands to alter, reprogram, lock, or disable tags. The existence of a rogue reader can be especially problematic in a commercial environment, where these implementations are used for asset management and security. 
         [0006]    Accordingly, there is a need for detecting the presence of rogue RFID readers in RFID implementations. 
       SUMMARY 
       [0007]    A system, techniques, and apparatus for detecting rogue RFID readers are disclosed. The system detects unauthorized reader to tag communication, and with multiple detectors, provides location information concerning one or more unauthorized readers. The system can detect high power commands of an unauthorized reader(s) in predefined areas and be integrated with an article surveillance system. 
         [0008]    For example, according to one aspect, a method of detecting unauthorized RFID reader to tag communication includes identifying an interrogating Radio Frequency (RF) wave directed to a population of RFID tags, the interrogating wave having a first intensity greater than a second wave intensity transmitted by each of the population of RFID tags, comparing source identifying information associated with the wave to source identifying information associated with at least one allowable RFID reader, and detecting an unauthorized RFID reader access to at least one of the population of RFID tags based on the comparison. 
         [0009]    In one embodiment, the method includes identifying the interrogating RF wave using a Digital Signal Processor. The Digital Signal Processor is operatively coupled to an authorized RFID reader. The method can also include generating an alert based on detection of the unauthorized RFID reader. In one embodiment, the method includes displaying the alert on a display device. 
         [0010]    In another embodiment, the method further includes determining location information of the unauthorized RFID reader using multiple authorized RFID readers configured to perform triangulation. The method can also include transmitting the location information to a surveillance system. For example, in one embodiment, the method includes directing a video component of the surveillance system toward a physical location representative of the location information. The method also can include determining whether a command associated with the interrogation wave is a read command, reprogram command, lock command, or disable command, and generating an alert based on the determination. In embodiments, the method also includes detecting a jamming signal based on the first intensity of the interrogating RF wave. 
         [0011]    In another aspect, an RFID reader includes an antenna, a transducer operatively coupled to the antenna to transmit and receive Radio Frequency (RF) waves, and a signal processor to process the waves. The signal processor is configured to include a processor and memory configured to include memory storing instructions that, in response to a request, cause the processor to identify an interrogating Radio Frequency (RF) wave directed to a population of RFID tags, the interrogating wave having a first intensity greater than a second wave intensity transmitted by each of the population of RFID tags. The signal processor compares source identifying information associated with the wave to source identifying information associated with at least one authorized RFID reader, and detects an unauthorized RFID reader access to at least one of the population of RFID tags based on the comparison. 
         [0012]    In one embodiment, the RFID reader further includes a Digital Signal Processor to identify the interrogating RF wave. The processor of the RFID reader can generate an alert based on detection of the unauthorized RFID reader. In one embodiment, the processor of the RFID reader displays the alert on a display device. 
         [0013]    In another embodiment, the processor of the RFID reader determines location information of the unauthorized RFID reader using triangulation and input from at least one additional authorized reader. The RFID reader can also transmit the location information to a surveillance system. For example, in one embodiment, the RFID processor sends instructions to the surveillance system to direct a video component of the surveillance system toward a physical location representative of the location information. 
         [0014]    In yet another embodiment, the processor of the RFID reader determines whether a command associated with the interrogation wave is a read, reprogram, lock, or disable command, and generates an alert based on the determination. The processor can also detect a jamming signal based on the first intensity of the interrogating RF wave. 
         [0015]    In yet another aspect, an RFID system includes a RFID tag and a RFID reader configured to transmit and receive Radio Frequency (RF) waves to the RFID tag. The RFID reader is configured to include a detection module that 1) identifies an interrogating Radio Frequency (RF) wave directed to the tag, the interrogating wave having a first intensity greater than a second wave intensity transmitted by the tag, 2) compares source identifying information associated with the wave to source identifying information associated with at least one allowable RFID reader, and 3) detects an unauthorized RFID reader access to the tag based on the comparison. 
         [0016]    In one embodiment, the RFID system further includes a plurality of RFID readers configured to determine a physical location of the unauthorized reader using triangulation. At least one of the plurality of RFID readers can be operatively coupled to an electronic article surveillance system for receiving and visually displaying the physical location of the unauthorized RFID reader. 
         [0017]    Various advantages can be obtained using the present invention. For example, the present invention can be integrated with an Electronic Article Surveillance system to provide location information regarding unauthorized readers. The invention can also be used to detect reader usage which could be, for example, a competitor attempting to gain a competitive advantage. Further, the invention can be applied to secret and military uses of RFID technology. 
         [0018]    Additional features and advantages will be readily apparent from the following detailed description, the accompanying drawings and claims. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0019]      FIG. 1  depicts an environment where an exemplary population of RFID tags is being interrogated by a plurality of trusted RFID readers. 
           [0020]      FIG. 2  illustrates a system where an exemplary rogue RFID reader is detected according to the present invention. 
           [0021]      FIG. 3  illustrates an exemplary method executed by the detection module to detect a rogue RFID reader or writer. 
           [0022]    Like reference symbols in the various drawings indicate like elements. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]      FIG. 1  describes a system  10 , which includes a population  12  of RFID tags  12 A-G, and trusted readers  14 A-D. As used herein, the phrase “trusted reader” refers to an authorized RFID reader in an environment. Trusted RFID readers  14 A-D may operate independently, or may be connected together to form a reader network. Although not shown explicitly in  FIG. 1 , each of the readers  14 A-D is coupled to one or more antennas. When a reader  14  transmits an interrogation signal  16  through its corresponding antenna, one or more transponders or tags  12  respond by sending a signal  16  back to the reader. Signal  16  contains tag identification data, that can be decoded by interrogating readers  14  in order to retrieve relevant information about a tag  12 , such as its price, location etc. Signal  16  may contain information about the operational “state” of a tag  12 , which assists readers  14 A-D in determining an optimum tag interrogation interval to interrogate the same population of tags. 
         [0024]    Interaction between tags  12 A-G and trusted readers  14 A-D takes place according to certain communication protocols. Examples of such protocols include Class 0, Class 1, and more recently developed Generation 2, all of which are different classes approved by the RFID standards organization EPCglobal (EPC=Electronic Product Code). 
         [0025]    Once tags are identified, individual tags may be addressed using their identifiers. For example, a reader may perform additional operations (e.g., read, write and lock) on a tag within its operational field by first transmitting a “select” command, including the identifier of the tag, setting the identified tag into a communicative state. The reader may then utilize additional commands (e.g., write block, read block, lock block, etc) to control or access data of the selected tag. For example, the reader may read data from one or more memory blocks of the selected tag using a read block command. In another example, the reader may write data to one or more memory blocks of the selected tag using a write command. In another example, the reader may prevent further changes to one or more memory blocks of the selected tag using a lock command. Thus, operations performed upon tags  12 A-G by trusted readers  14 A-D typically involve first selecting the tag using its identifier and then reading or writing data from and to the selected tag. 
         [0026]    Turning now to  FIG. 2 , a typical RFID system  20  incorporating aspect of the present invention is disclosed. The system  20  can detect the presence of a rogue reader  24 . As used herein, the phrase “rogue reader” refers to any unauthorized RFID reader that attempts communication with a RFID tag in a predefined area. 
         [0027]    As shown in  FIG. 2 , the system  20  can include a plurality of trusted readers  22 A-D that receive and transmit interrogation signals  28  to and from the population  12  of RFID tags  12 A-G. In one embodiment, as  5 shown in  FIG. 2 , the system  20  is integrated with an electronic article surveillance system  26 . The surveillance system  26  includes a plurality of video components, such as video cameras  26 A-C, that can be directed at various angles to view objects, such as tags and readers, in the pre-defined area. 
         [0028]    Trusted readers  22 A-D are preferable configured to communicate with one another and are arranged to form a reader network. The reader network can be used to detect and identify commands and locations of rogue or unauthorized RF transmitters  24  attempting to read tags, reprogram writable tags, and/or issuing kill commands by sending a RF signal  24 A to the tags  12 . For example, the issuance of a kill command from the rogue reader  24  shown in  FIG. 2  can permanently disable one or more tags  12 , and render the tags  12  useless and the item or individual to which the tag is attached undetectable by trusted readers  22 A-D. 
         [0029]    The network of readers can be used to determine the location of the rogue reader  24  via wired (e.g., Ethernet) or wireless (e.g., IEEE 802.11) signaling. Specifically, in one embodiment, the trusted readers  22 A-D are configured to monitor each others&#39; backbone transmissions and/or tag transmissions, and use the times of signal arrival, time differences of signal arrival, and information relating to antenna beam pointing, antenna nulling, and received signal strength to determine the physical location of the rogue readers  24  in the system  20 . This technique can be used to enhance security by determining the locations of one or more rogue readers that may have been inserted into the reader network, and which may attempt to communicate via the reader backbone. As described below, received signal information can then be compared against expected values for signals from trusted readers, and any deviations (which may be indicative of rogue reader commands) can be reported to the system operator (Operator) via an alerting mechanism. Further, location information of the rogue reader  24  can be determined and transmitted to the article surveillance system  26 . 
         [0030]    Trusted readers  22 A-D are preferably configured to include a detection module  30  that can identify an interrogating Radio Frequency (RF) wave directed to the population  12  of RFID tags  12 A-G. One or more of the trusted readers  22 A-D can be configured to include a digital sensor processor to sense RF wave intensities being transmitted to and from population of tags  12 A-G. If an interrogating wave has an intensity greater than a typical wave intensity transmitted by the population of RFID tags, the detection module  30  determines that the rogue reader  24  may be present in the system  20 . 
         [0031]    For example, in one embodiment, if the detection module  30  detects an interrogating wave having an intensity greater than a typical wave intensity transmitted by the population of RFID tags  12 A-G, the detection module  30  compares source identifying information associated with the interrogating wave to source identifying information associated with trusted RFID readers  22 A-D. In one embodiment, source identifying information associated with trusted RFID readers  22 A-D is stored and accessible from a database. If the source identifying information does not match authorized sources, the detection module  30  detects the presence of the rogue reader  24 . In one embodiment, the detection module also determines whether a command associated with the interrogation wave is a read tag command, reprogram tag command, lock tag command, or disable tag command, and provides the determination in the alert. 
         [0032]    Once an alert is generated, the detection module  30  displays the generated alert on a display device  24  operatively coupled to the trusted reader. In another embodiment, the alert is displayed on a remote display device. Thus, corrective action can be taken by the system  20 , by an operator associated with the system  20 , or otherwise, to remove and/or reduce the influence of the rogue reader  24 . 
         [0033]    Based on the number and configuration of trusted readers  22 A-D in the system  20 , the system  20  can provide location information of the unauthorized RFID reader  24 . 
         [0034]    For example, in one embodiment, where trusted readers  22 A-D are arranged in a reader network, readers  22 A-D are time synchronized and operative to time-stamp the time of reception of RF signals transmitted by reader devices, including any rogue readers, thereby allowing information received by different readers to be combined for the purpose of locating the rogue reader  24  and generating alerts comprising location information. In one embodiment, the process of determining the physical location of the rogue reader  24  includes calculating a time difference of signal arrivals by combining information relating to time-stamped signal receptions. It is noted that knowledge of the signal arrival times and signal transmit times generally provides sufficient information for performing rogue reader profiling and triangulation of the rogue reader  24 . 
         [0035]    In alternative modes of operation, at least one trusted reader is operable to determine the difference between the carrier frequency employed in its own RF transmissions and that employed in the RF transmissions of other reader devices, and to pass that information along to one or more other trusted reader devices to detect the presence of the rogue RFID reader  24 . Further, the at least one trusted reader is operable to capture a digitized received modulation waveform (time stamped), and to forward it to another device for remote analysis/correlation, such as a server. 
         [0036]    Once the rogue reader location information is determined, in an embodiment, any of the trusted readers  22 A-D can transmit the location information to the electronic surveillance system  26  which, as shown in  FIG. 2 , can include various video components, such as but not limited to video cameras  26 A-C. For example, as shown in  FIG. 2 , once the existence and location of rogue reader  24  is determined by the plurality of trusted readers, one of the trusted readers  22 B can transmit the location information  25  to the surveillance system  26 . In some embodiments, one of the trusted readers  22 B directs a video component of the surveillance system, such as the cameras  22 A-C, toward the physical location representative of the location information for viewing or filming by system operators or the system  20 . 
         [0037]    Advantageously, the system  20  can be synchronized with trusted readers in a particular area to avoid false positives. The system can also be used to detect simple reader usage (not altering) which could be, for example, a competitor attempting to gain strategic knowledge of tagged product items. 
         [0038]    Still further, the system can be used to determine jamming signals from rogue readers. For example, in instances where trusted readers may have received a corrupted response from tags, the system  20  can determine that an area around one of the tags is suffering from unwanted interference. The detection module  30  can generate an alert and corrective measures can then be taken by trusted readers, an operator of the system, or otherwise. 
         [0039]    Turning now to  FIG. 3 , in one embodiment, a method executed by the detection module  30  of the present invention is disclosed. It will be appreciated by one skilled in the art that the steps disclosed in  FIG. 3  are merely exemplary and can be modified and combined in various ways without limiting the scope or breath of the present disclosure or claims. First, as shown in  FIG. 3 , the detection module  30  of a trusted reader identifies an interrogating radio wave frequency in the system  50 . Next, the detection module determines if the intensity of the wave exceeds a wave intensity of transmitting tags  52 . If the intensity of the wave exceeds the wave intensity of transmitting tags, the detection module  30  compares source identifying information associated with the identified wave to a list of trusted RFID reader sources  54 . In one embodiment, as described previously, the list of trusted reader sources can be stored in a database and be accessible to the detection module  30 . Next, the detection module  30  detects an unauthorized reader in the system based on the comparison  56 . The detection module  30  then generates and displays an alert indicating the existence of the rogue RFID reader based on the comparison  58 . In embodiments of the system  20  that include a network of trusted readers  22 A-D, the detection module  30  determines the location information of the rogue reader  24  using a triangulation technique  60  and input data from at least one other trusted reader, as described previously. Finally, in one embodiment, the detection module  30  transmits the location information to an electronic article surveillance system along with instructions  62  to direct video components of the system  26 , such as cameras  26 A-C toward a physical location of the rogue reader  24  for viewing or filming. 
         [0040]    Various features of the system may be implemented in hardware, software, or a combination of hardware and software. For example, some features of the system may be implemented in computer programs executing on programmable computers. Each program may be implemented in a high level procedural or object-oriented programming language to communicate with a computer system or other machine. Furthermore, each such computer program may be stored on a storage medium such as read-only-memory (ROM) readable by a general or special purpose programmable computer or processor, for configuring and operating the computer to perform the functions described above.