Abstract:
A wide area radio frequency identification (RFID) system includes: a first RFID cell and a second RFID cell. The first RFID cell and the second RFID cell each include a reader and tags. The readers access the tags using ultra-wide band signaling. The RFID cells each include: a communications interface operable to communicate with a network operations center, and a communications gateway which supports direct communications between RFID cells. The method includes accessing the second RFID cell from the first RFID cell, and the accessing is performed using the communications gateway that can cover a range of at least five hundred meters.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 12/066,697, filed Aug. 19, 2008, which is the National Stage of International Application No. PCT/IL2006/001138, filed Sep. 28, 2006, which claims priority from U.S. Provisional Application Ser. No. 60/721,986, filed on Sep. 30, 2005, the contents of which are each incorporated by reference herein in their entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to an RFID system including readers and tags, using ultra-wide band (UWB) communications between the readers and the tags, and the RFID system is managed over a wide area between RFID cells separated over a wide area, e.g., several kilometers or more. Specifically, the method includes communications links operable between RFID/UWB cells for transferring data between the cells. 
       BACKGROUND OF THE INVENTION 
       [0003]    Radio Frequency IDentification (RFID) is a method of storing and remotely retrieving data using devices called RFID tags. An RFID tag is a small object that can be attached to a product, animal, or person. RFID tags receive and respond to radio-frequency queries from an RFID reader. RFID tags can be either active or passive. Passive tags require no internal power source, whereas active RFID tags have an internal power source, and typically have longer range and larger memories than passive tags. 
         [0004]    An RFID system includes several components including mobile tags, tag readers, and application software. The RFID system enables a query to be received by the mobile tag and the tag responds with data. The data is received by an RFID reader and processed according to the needs of a particular application. The data transmitted by the tag may provide identification or location information, or specifics about the product tagged, such as price, color, date of purchase. 
         [0005]    RF identification (RFID) systems are used to track objects, animals and/or people in a large range of applications. As an example, RFID is used to track books in a library. Security gates include an RF transceiver as part of the RFID reader which detects whether or not a book has been properly checked out of the library. When the book returns, the tag attached to the book is detected and an appropriate record is updated in the library system. In. another application, RFID readers previously located in a warehouse are used to identify certain objects (for example, on a track entering the warehouse), or to find the location of certain objects, by communicating with their tags and measuring the position of their tags. 
         [0006]    A RFID system employs tags on various objects and readers of the tags in a given space. The main function of an RFID is to enable identifying the objects and possibly reading and writing data of the objects to and from the respective tags. Often the RFID system allows tracking the location of the objects via the respective tag location. 
         [0007]    Ultra-wide band communications is particularly useful for determining distance and location of RFID tags. PCT International Patent Application Publication No. WO 2003/098528, (PCT Patent Application No. PCT/IL2003/00358), entitled “Method and system for distance determination of RF tags” is incorporated by reference for all purposes as if fully set forth herein. PCT/IL2003/00358 discloses an RFID system having the capability of automatically identifying unknown tags by sending a broadcast interrogation ultra wide-band (UWB) message signal and receiving responses from tags that receive the message signal. 
         [0008]    As known in the art of RFID systems, the readers are devices which identify and store the data from the tags. The tags are attached to assets or materiel being managed. A major goal of an RFID system is to allow asset visibility to the organization and improve the organization&#39;s efficiency in asset tracking within different processes within the organization. The RFID system is a useful tool to obtain resource and location information for resource management or materiel management applications such as computer resource management (CRM) or Enterprise Resource Planning (ERP) applications running on interconnected computers within the organization. Typically the readers of the RFID system collect data originating in the tags, communicate and transfer the data with the resource management applications. 
         [0009]    An RFID system  10  of the prior art is shown in  FIG. 1  including readers  101  communicating with tags  103 . Readers  101  are optionally connected to a conventional data switch  100  using Ethernet (e.g., 100 BaseT) connections  105 . RFID system  10  employing wide-band transmission can cover only limited areas, of typical dimension no more than several hundred meters. This is particularly the case for a RFID system employing ultra-wide band (UWB) communications networks using impulse transmission or otherwise complying with the definition of ultra wide (UWB) as approved by the FCC, or other wide-band communication methods. 
         [0010]    Wide-band, low data rate systems (including RFID systems) fall under the category of personal area networks (PAN) and cover a limited area. In some cases, the low data rate systems include several readers that are used to cover the area, whereas tags  103  within this area can communicate with one or more readers  101  within the area. Information regarding tagged objects may be relayed between different RFID tag cells, according to the prior art from readers  101  through switch  100  to a wide area network such as the Internet to a network operations center (not shown). 
         [0011]    In numerous cases, there exists a need to cover a wide area in which assets or objects may move. Due to the limited coverage capability of an RFID system employing UWB, other communications systems are required to achieve the coverage over the wide area. A conventional method for covering a wide area is disclosed in US application 20040203377 entitled, “Communication system for dynamic management of a plurality of objects and method therefor”. In US patent application publication 20040203377, the objects are located within a large coverage area, and communicate their information to a central server. The objects may belong to dynamic groups controlled by group controllers. Another representative prior art reference is US patent application publication 2005/0248454 entitled “Marine Asset Security and Tracking System” as disclosed by Hanson et. al. Hanson et. al disclose a system using radio frequency identification (RFID) tags installed on containers. Multiple RFID readers are required, e.g., on ship, which relay information from the RFID tags to a site served installed on ship or in port. The site server relays information regarding the monitored containers via satellite link to a network operations center (NOC). 
         [0012]    However, in many cases a central server or network operations center is not readily available either due to lack of worldwide coverage or insufficient capacity. In other cases, such as when the connection to a network operations center (NOCRO requires the use of low earth orbit (LEO) satellites the satellite communication connection is very expensive. 
         [0013]    There is thus a need for, and it would be highly advantageous to have a wide area dynamic RFID system using UWB which does not always require the use of a central server nor a network operations center (NOC) for communicating between one RFID/UWB cell to another RFID/UWB cell. 
         [0014]    Other Prior Art: 
         [0015]    US patent application publication 20050208892, Kotola et al., entitled “System and Method for remote service operation”, provides techniques for the management of information regarding remote services. A remote service link is received across a short-range wireless communications network. The remote services may provide location-specific information regarding topics, such as weather forecasts, local dining and shopping, maps, transit schedules, etc. A mobile device may store and display information that allows a user to initiate service sessions with various remote service providers. 
         [0016]    US patent application publication, 20050198208, S. Nystrom, “Accessing data in a short-range wireless communication network” describes a short-range communication system, including a transponder and mobile reader device that integrates information stored on a short range communications tag with information stored remotely at an external network resource. The user of a reader-associated device can access information stored on a short-range communication tag and information stored remotely at a network resource without incurring unnecessary delay. The system of US20050198208 includes a short-range wireless communication tag. The tag includes short-range wireless communication circuitry and a memory unit in communication with the circuitry. The memory unit stores local content information, e.g., Internet home page, and commands for concurrently effecting retrieval of supplemental content information, associated with the local content information from a remote network resource while the local content information is accessible to a remote wireless device. 
       DEFINITIONS 
       [0017]    The term “ultra-wide band” (UWB) as used herein is defined (by FCC and ITU-R) in terms of a transmission from an antenna for which the emitted signal bandwidth exceeds the lesser of 500 MHz or 20% center frequency. Ultra-wide band (UWB) communication technology employs discrete pulses of electromagnetic energy that are emitted at, for example, picosecond to microsecond intervals. For this reason, ultra-wide band is often called “impulse radio.” A UWB pulse is a single electromagnetic burst of energy. A UWB pulse can be either a single positive burst of electromagnetic energy, or a single negative burst of electromagnetic energy, or series of pulses. Each pulse in a pulse-based UWB system occupies the entire UWB bandwidth, e.g., 3.1 to 10.6 GHz. thus having relative immunity to multipath fading (but not to intersymbol interference), unlike carrier-based systems that are subject to both deep fades and intersymbol interference. 
         [0018]    Ref: http://en.wikipedia.org/wilci/Ultra_wide band. 
         [0019]    The terms “cell” or “RFID cell” as used herein is an RFID network using ultra wide band signaling over a limited area, typically up to a few hundred meters in dimension. 
         [0020]    The terms “personal area network” (PAN) and “RFID cell” are used herein interchangeably. 
         [0021]    The term “wide area” in the context of the present invention, refers to an area with typical dimensions of at least five hundred meters up to several kilometers or more. Coverage need not be contiguous over the wide area but rather only within the RFID cells in which the assets or tagged objects are located. 
         [0022]    The terms “direct” or “directly” referring to communications between RFID cells without communicating through a network operations center. 
         [0023]    The term “materiel” as used herein refers to the equipment and supplies in military and commercial supply chain management. In a military context, the term “materiel” relates to the specific needs of an army to complete a specific mission. Materiel in the context of commercial distribution includes items being transported by the services of or as the products of the business. 
         [0024]    Integrated Digital Enhanced Network (iDEN) is a mobile telecommunications technology, developed by Motorola, which provides benefits of a trunked radio and a cellular telephone. iDEN places more users in a given spectral space, compared to analog cellular and two-way radio systems, by using speech compression and time division multiple access (TDMA). Notably, iDEN is designed to operate on narrow Specialized Mobile Radio (SMR) spectrum, rather than cellular frequencies. This necessitates the use of time division duplex, since SMR frequencies are unpaired. Up to six communication channels share a  25  kHz space; where analog two-way systems place only one channel in 12.5 kHz. 
         [0025]    (Ref: http://en.wikipedia.org/wiki/Integrated_Digital_Enhanced_Network) 
       SUMMARY OF THE INVENTION 
       [0026]    According to the present invention there is provided a wide area radio frequency identification (RFID) system including RFID cells. The RFID cells include readers and tags. The readers access the tags using ultra-wide band signaling. The RFID cells each include a communications interface operable to communicate with a network operations center, and a communications gateway operable to support direct communications between the RFID cells. The direct communications is over a range of at least five hundred meters. Typically, one or more of the RFID cells are located in a mobile vehicle. The ultra-wide band signaling is preferably operable to determine respective locations of the tags and to store the respective locations. The communications gateway preferably includes a cellular telephone communications interface and a cellular telephone operatively attached to or integrated with the reader. The communications gateway is operatively attached to a communications link using a communications technologies such as cellular communications, terrestrial radio communications, satellite communications, point-to-point microwave communications, infrared free space point-to-point communications, and free space point-to-point optical communications. The tags are attached to objects included in materiel of an organization, The objects are managed by a materiel management application accessible through the network operations center. 
         [0027]    According to the present invention there is provided a method in a wide area radio frequency identification (RFID) system. The system includes a first RFID cell and a second RFID cell. The first RFID cell and the second RFID cell each include a reader and tags. The readers access the tags using ultra-wide band signaling. The RFID cells each include: a communications interface operable to communicate with a network operations center (NOC), and a communications gateway which supports direct communications between RFID cells. The communication interface to the NOC and the communication gateway, may be housed in the same device or in different devices. The method includes accessing the second RFID cell from the first RFID cell, and the accessing is performed using the communications gateway over a range of at least five hundred meters. Typically one or more of the RFID cells is located in a mobile vehicle. An RFID cell is capable of receiving a security alarm from another RFID cell. Transmissions from the RFID cell are optionally unicast, multicast and/or broadcast transmissions. A reader in one RFID cell can access a tag, of another RFID cell, either by querying information from the tag; or by writing data to the tag; or the reader in the RFID cell accesses another reader of the other RFID cell. By virtue of ultra-wide band signaling, a reader in one RFID cell preferably maintains in storage locations of the tags in the RFID cell. The locations may be queried typically by a reader from the other cell. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein: 
           [0029]      FIG. 1  is a prior art drawing of a conventional RFID cell; and 
           [0030]      FIG. 2  is a drawing according to an embodiment of the present invention of a wide area RFID system using UWB. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0031]    The present invention is of a system and method of providing a wide area dynamic RFID system using UWB. Specifically, the system and method includes multiple RFID systems using ultra wide band (UWB) signaling between readers and tags  103  and information regarding tagged objects is transferred over relatively large distances between multiple RFID systems using communications links. A wide area RFID/UWB network is thus achieved which is preferably managed in a similar way to a single RFID cell. The communication links which allow mesh connectivity between RFID cells may be achieved using a cellular network, a satellite network, terrestrial radio, or point-to-point links such as microwave, infrared or optical links. 
         [0032]    The principles and operation of a system and method of providing a wide area dynamic RFID system using UWB, according to the present invention, may be better understood with reference to the drawings and the accompanying description. 
         [0033]    Before explaining embodiments of the invention in detail, it is to be understood that the invention is not limited in its application to the details of design and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting. 
         [0034]    By way of introduction, a principal intention of the present invention is to provide a wide area RFID network in which RFID cells are separated by large distances, e.g., several kilometers and information transfers between RFID cells using communications links between RFID cells. The information transfer between the RFID cells is performed using the communications links between the cells particularly when the central server or network operations center (NOC) is unavailable, e.g., no cellular coverage, or otherwise undesirable, e.g., too costly for frequent updates such as in the case of using a low Earth orbit satellite network. Another intention of some embodiments of the present invention is to reduce management overhead by managing the wide area RFID network much in the same way as if it were a single RFID cell. The wide area RFID network, according to embodiments of the present invention, maintains accurate location information regarding organizational or corporate assets i.e., tagged objects, using communications links between the cells. The wide area RFID network updates location information of the tagged objects, preferably only as required, e.g., once per day or upon query through the network operations center to the enterprise resource management application. In this way, communications using the network operations center is minimized. Another intention of embodiments of the present invention is to increase security since multiple communications links need to be jammed to prevent the reader from transmitting an alarm. 
         [0035]    The wide area RFID network, according to different embodiments of the present invention may include static RFID cells such as in a warehouse, or mobile RFID cells which include tagged objects in a truck, container, ship or airplane or a combination of mobile and static RFID cells. Similarly; the readers in different embodiments of the present invention may be immobile within a warehouse, at a vehicle entrance or docking points; or the readers may be mobile within trucks, ships, airplane and other vehicles. In other embodiments, different mobile cells may become sufficiently close, e.g. within 100 meters, to overlap and the tags of one cell may be accessed by the reader of another cell nearby using UWB signaling and synchronization. 
         [0036]    Referring now to the drawings,  FIG. 2  illustrates schematically a wide area dynamic RFID system  20  using UWB, according to embodiments of the present invention. Wide area RFID system  20  includes multiple RFID cells or PANS  11 . In each PAN  11  there is gateway device  201  which connects to other cells  11  via connections  203 . Gateway device  201  may be integrated with UWB reader  101  of the RFID system  10 . Gateway device  201 , is preferably accessible by query from network operations center  207  when a conventional WAN connection  205  is available. Gateway device  201  may be used to access readers  101  in the same cell  11 , particularly when reader  101  is not accessible for some reason using conventional UWB signaling. In some embodiments of the present invention, gateway  201  is a mobile telephone such as cellular, e.g., GSM, telephone or iDEN, since iDEN doesn&#39;t require a nearby base station to establish communications. In some embodiments of the present invention, UWB reader  101  is built into the same housing as the mobile telephone, enabling full RFID functionality within cell  11 . Gateway device  201  and connection  203  may use any known type of communications known in the art including radio, free space point-to-point microwave, infrared or optical links. 
         [0037]    In each PAN  11  of wide area RFID system  20 , network topology and Media Access Control (MAC) protocols may be similar to those specified by IEEE 802.15.4 standard, or any other suitable protocol. 
         [0038]    According to embodiments of the present invention, operation of wide area RFID network  20  using RFID operates using an innovative protocol. Wide area RFID network  20  protocol between RFID cells  11  preferably includes the following elements: 
         [0039]    A message (and response message) for identifying all objects in cell ‘n’; 
         [0040]    A read of data from object ‘y’ in cell number ‘n’; 
         [0041]    Write operation of data ‘d’ to object ‘x’ in cell ‘n’; 
         [0042]    Find location of object ‘z’ in cell number ‘k’; 
         [0043]    An outgoing (alert) message from one cell  11  to another cell  11  or to NOC  207 : event ‘eee’ occurred in element ‘w’ of cell (or a security event, out of list of prescribed events). 
         [0044]    In wide area RFID network  20 , ‘read’ (object data or object ID), ‘write’ (object data) and ‘locate’ (an object) have both a local meaning (inside PAN  11 ) as well as a global meaning in wide area RFID network  20 . Reader  101  in one RFID cell  11  may transmit a query for a tagged object in the same cell  11  or in another cell  11 , by either an addressed unicast, multicast message or by a broadcast message. Reader  101  may also write data to a tagged object in local RFID cell  11  or in another RFID cell. Furthermore, reader  101  may be required to find the location of a tagged object, either in local RFID cell  11 , or in another RFID cell  11  of wide-area network  20 . The absolute (e.g. geographic) location of objects in any RFID cells  11 , may be measured (such as using the teachings of WO 2003/098528) if the absolute location of readers  101  is known. In the case of a immobile RFID cell  11 , the location of readers  101  is typically known a priori. Otherwise, the location of readers  101  may be determined for instance using an attached global positioning system (GPS). If the absolute location of reader  101  is not available, the location of a tagged object can be specified based on a relative location of one or more readers  101 . In either case, the computation to determine location of tagged objects is performed locally or remotely over the wide area RFID network  20  using a centralized processing machine or server (not shown) preferably co-located with one of gateways  201 . 
         [0045]    The usage of wide area RFID system  20  may be further augmented for various combinations of local and global processes, for example: 
         [0046]    Wide area RFID system  20  may support additional mechanisms of information transfer e.g., video transmission to the Network Operation Center  207 , e.g., for emergency situations triggered by the occurrence of a local event. Wide area RFID system  20  may be used to synchronize processes in different PANs  11  very close to real time, e.g. by updating records, such as shipment dates or destinations written on tagged objects in one PAN  11 , in response to an event in another PAN  11  or in response to the command of materiel management application. 
         [0047]    When gateway  201  is a cellular telephone integrated with UWB reader  101 , the cellular telephone has a network identification, is manually operable through a conventional keypad, or automatically places calls to NOC  207  or other gateways or responds to calls from NOC  207  or other gateways  201 . 
         [0048]    One application of the present invention is in the military theater. Typically, modem armies are required to maintain and secure weapon inventories. An RFID/UWB cell  11  is located in each weapons warehouse or truck carrying weapons. If one military unit requires weaponry from a second unit, a multicast (or broadcast) query may be placed over communications links  203  to locate the required weaponry from neighboring cells  11  of other military units. 
         [0049]    In another application of the present invention, a telecommunications company in a modem city has several trucks with replacement parts, e.g., switches or circuit boards. One technician may require a replacement part which is not available on his truck. The technician performs a multicast query over communications links  10 , to perform an inventory search in neighboring cells  11 , e.g. trucks to locate the required part a nearby cell  11 . 
         [0050]    As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
         [0051]    While the invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications and other applications of the invention may be made.