Patent Description:
A typical RFID system may be at least used in a material handling environment (e.g. a distribution center, a warehouse etc.) for tracking assets (e.g., but not limited to, articles, items, packages, shipments, boxes, etc.). In some examples, one or more RFID tags may be placed or attached to one or more assets that are to be tracked. In some examples, these assets may be located on various predefined storage locations (e.g., but not limited to, shelves of a storage location) within the material handling environment. Further, in some examples, the RFID system may include a distributed antennas set-up, i.e. an antenna configuration including multiple RFID antennas that may be installed at various locations. In some examples, these antennas may be communicatively coupled to one or more RFID readers and can be used to communicate RF interrogation signals received from the readers to the RFID tags for tracking the assets. In some examples, the RFID antennas and the one or more RFID readers may be connected over a distributed communication network. In some examples, the one or more RFID readers may be configured to read via the multiple RFID antennas, the one or more RFID tags (placed on the one or more assets) either continuously or periodically, thereby, tracking the assets.

<CIT> discloses a method of object localization with an RFID infrastructure in which a plurality of transmission power levels established by an RFID reader are searched to determine a measurement power level corresponding to a target. A region that includes the target can then be determined using information about a physical relationship between the RFID reader and a reference location via correlating the measurement power level to a reference power level corresponding to the reference location.

According to the present invention there is provided a method as defined in claim <NUM>, to which reference should now be made. Optional features are defined in the dependent claims. Moreover, examples, embodiments, and descriptions, which are not covered by the claims are presented not as embodiments of the invention, but as background art or examples useful for understanding the invention. In general, embodiments of the present disclosure provided herein identify RFID tags and locations associated therewith. Other implementations for identifying RFID tags and locations associated therewith will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description.

In accordance with a first aspect of the disclosure, a computer-implemented method is provided. The computer-implemented method is implementable via any of a myriad of computing devices embodied in hardware, software, firmware, and/or any combination thereof as described herein.

In some embodiments of the example computer-implemented method, causing activation of the plurality of antennas at the plurality of transmit power levels, comprises sequentially activating the plurality of antennas at the plurality of transmit power levels.

In some embodiments of the example computer-implemented method, causing activation of the plurality of antennas at the plurality of transmit power levels comprises activating each antenna of the plurality of antennas with a particular power level to a maximum transmit power level of the plurality of transmit power levels; and incrementally decreasing the particular power level of each antenna of the plurality of antennas until the particular power level reaches a minimum power level of the plurality of transmit power levels.

In some embodiments of the example computer-implemented method causing activation of the plurality of antennas at the plurality of transmit power levels comprises activating each antenna of the plurality of antennas with a particular power level to a minimum transmit power level of the plurality of transmit power levels; and incrementally increasing the particular power level of each antenna of the plurality of antennas until the particular power level reaches a maximum power level of the plurality of transmit power levels.

In some example embodiments of the computer-implemented method, the computer-implemented method further comprises selecting the plurality of frequency channels based on a set of frequency dwell times associated with the plurality of antennas.

In some example embodiments of the computer-implemented method, determining the confidence score for a particular antenna of the plurality of antennas comprises determining a plurality of weightage parameters comprising a weightage parameter corresponding to each transmit power level of the plurality of transmit power levels; and generating a plurality of values corresponding to the plurality of power levels, wherein the plurality of values comprises a value generated for each particular transmit power level of the plurality of power levels based at least in part on (<NUM>) the sub-count of tag reads associated with the antenna at the power level and each frequency channel of the plurality of frequency channels, and (<NUM>) the weightage parameter corresponding to the particular transmit power level from the plurality of weightage parameters; and calculating the confidence score from the plurality of values corresponding to the plurality of power levels.

In some example embodiments of the computer-implemented method, the computer-implemented method further comprises triangulating the RFID tag based at least in part on signals received in response to activation of the plurality of antennas.

In some example embodiments of the computer-implemented method, the computer-implemented method further comprises randomly determining the plurality of frequency channels.

In some example embodiments of the computer-implemented method, generating a confidence score for a particular antenna of the plurality of antennas comprises determining a plurality of first weightage parameters comprising a weightage parameter corresponding to each transmit power level of the plurality of transmit power levels; determining a plurality of second weightage parameters comprising a weightage parameter corresponding to each frequency channel of the plurality of frequency channels; generating a plurality of values corresponding to the plurality of power levels and the plurality of frequency channels, wherein the plurality of values comprises a value generated for each particular transmit power level of the plurality of power levels and each particular frequency channel of the plurality of frequency channels based at least in part on: for each transmit power level of the plurality of transmit power levels, the sub-count of tag reads associated with each frequency of the plurality of frequency channels; a first weightage parameter of the plurality of first weightage parameters; and the plurality of second weightage parameters corresponding to each frequency channel of the plurality of frequency channels; and calculating the confidence score from the plurality of values corresponding to the plurality of power levels and the plurality of frequency channels.

In some example embodiments of the computer-implemented method, generating the confidence score for a particular antenna of the plurality of antennas comprises executing a summation of the count of tag reads corresponding to the particular antenna for each transmit power level of the plurality of transmit power levels.

In accordance with another aspect of the invention, there is provided an apparatus according to claim <NUM>. The apparatus comprises at least one processor and at least one memory having computer-coded instructions stored thereon. The computer-coded instructions, in execution via the at least one processor, configure the apparatus to perform any one of the computer-implemented methods described herein.

In accordance with yet another aspect of the invention, there is provided a computer program product according to claim <NUM>. The computer program product comprises at least one non-transitory computer-readable storage medium having computer program code stored thereon. The computer program product, in execution with at least one processor, is configured for performing any one of the example computer-implemented methods described herein.

Terminology used in this patent is not meant to be limiting insofar as devices described herein, or portions thereof, may be attached or utilized in other orientations.

The term "comprising" means including but not limited to and should be interpreted in the manner it is typically used in the patent context. Use of broader terms such as "comprises," "includes," and "having" should be understood to provide support for narrower terms such as "consisting of," "consisting essentially of," and "comprised substantially of.

The phrases "in one embodiment," "according to one embodiment," and the like generally mean that the particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present disclosure, or may be included in more than one embodiment of the present disclosure (importantly, such phrases do not necessarily refer to the same embodiment).

The term "radio frequency (RF) tag" is used herein to correspond to an electronic component that transmits or receives information or date via an antenna. In some examples, the RFID tag includes an integrated circuit (IC), an antenna element, and a substrate. In an example embodiment, the antenna element can be fabricated on the substrate and the IC can be attached to the substrate. Further, the IC can be communicatively coupled to the antenna element through an interconnect on the substrate. In an example embodiment, the integrated circuit in the RFID tag can be configured to store encoded information or encoded data. In some examples the RFID tag can be configured to operate in various RF frequency bands such as, but not limited to, <NUM> (hereinafter High Frequency Band) or <NUM>-<NUM> (UHF band). In some example embodiments, the RFID tag can have a dedicated power source that can enable the RFID tag to communicate with one or more components, such as an RF encoder and an RF reader. Such RFID tags are referred to as active RFID tags.

In alternative example embodiments, the RFID tag may not have a dedicated power source. In such embodiments, the RFID tag can have a power coupler that can be capable of inducing electrical charge when the RFID tag is brought in an RF field. The induced electrical charge is thereafter used to power the RFID tag, itself.

In some example embodiments, an environment (e.g., but not limited to, a warehouse, an inventory, a distribution center, a material handling environment, a logistics transport carrier, and/or the like) may include a distributed antenna network set-up having a plurality of RFID antennas that may installed at various locations. Further, the environment may also include one or more RFID readers that may communicate with one or more of the plurality of RFID antennas to interrogate RFID tags. In some examples, an RFID tag may be associated with an asset (e.g. a shipment, a cart, a package, an item, a product, etc.) to track and identify the asset within the environment. Such environments may include an RFID system configuration having distributed RF antennas. Typically, distributed antenna systems are used in the wireless field for many applications (e.g., to boost broadband mobile wireless coverage). For example, distributed antenna systems may include many antennas tuned to match the area, such as of a building or venue or an area of a storage location (e.g. inventory) where increased signal strength or a boosted service is desired or needed. Usually, in order to use RFID technology in a distributed antenna system environment, multiple readers or multiple antenna multiplexers (controllers), controller devices (e.g., readers and/or multiplexers) and coaxial cables can be used. Said that, some example embodiments described herein relates to an RFID system having such configuration of the distributed antennas that may operate over RF and may be installed in the industrial environment (e.g. a warehouse) to identify RF tags associated with assets.

According to an example environment, an RFID tag can be associated to each asset stored in a warehouse. To this end, in some cases, to locate an asset from amongst multiple assets in the warehouse, a worker may use an RFID reader (e.g., but not limited to, of a portable data terminal-"PDT") to interrogate the RFID tag associated with the asset. Said that, in such environment, it is desired to reduce an amount of time spent by the worker in locating the asset to improve overall worker productivity and increase throughput. In some examples, for locating the asset, the worker may reach an approximate storage location, however, may still need to search through all of these assets to find a desired asset box.

Typically, for locating and tracking assets in such environment, the RFID tags associated with the assets are interrogated by the RFID reader used by the worker. In some examples, the environment may include high powered RF systems where active RFID tags may be associated with assets for tracking purposes. In this regard, RF parameters associated with RFID reader and RFID tags (such as, but not limited to, signal strength associated with RF interrogation signals and phase angle) can be used to locate a desired RFID tag from amongst the multiple RFID tags associated with respective assets. However, active RFID tags are generally costly hence, usually, passive RFID tags are used with assets for asset tracking. In such cases, using the signal strength and phase angle related RF parameters for detecting desired passive RFID tag is ineffective and has associated limitations, due to various factors, for instance, weak RF signal values. Further, using the RFID reader to interrogate RFID tags associated with assets for tracking packages in a confined environment becomes more challenging, in instances, where the environment includes many metallic surfaces (e.g. of shelves in a warehouse etc.) due to presence of RF reflection and noise that impacts the performance of overall RFID system. Furthermore, at times, finding a location of the RFID tag associated with an asset in a confined environment involves manual intervention, which is challenging and impacts productivity.

Various example embodiments described herein relates to an RFID system for identifying an RFID tag, for example, from amongst multiple RFID tags. By way of implementation of embodiments described herein, an approximate location of a desired RFID tag within an environment is identified by the RFID system. In some example embodiments, the RFID system can comprise, an RFID reader, an array of antennas that can be installed at various locations within an area, and a plurality of RFID tags associated with respective assets. In embodiments, the RFID reader of the RFID system is configured to detect an approximate location of a desired RFID tag in an area.

In some example embodiments, the RFID reader of the RFID system may be configured to sequentially power each antenna of the array of antennas array located in the area. In this regard, sequentially powering the antennas may include powering up by the RFID reader, one antenna at an instance of time, a next antenna at a next time instance, and so on. Said that, in embodiments, the RFID system is configured to vary a transmitted level of power (e.g., a "transmit power") at which a radio transceiver of the RFID reader can be operated. In some example embodiments, in response to sequentially powering each antenna, the RFID reader can be configured to gradually decrease the power of each antenna to identify the antenna that last read the RFID tag. In one example that does not embody the invention, the approximate location of desired RFID tag can be identified from the location of antenna that last read the tag, further details of which are described later in the description.

In one example that does not embody the invention, the RFID system may be configured to utilize a binomial search to locate an antenna that may be closest to desired RFID tag. In this regard, the RFID system may utilize a user-defined minimum power level and a user-defined maximum power level to which the antennas may be powered. Further, the RFID reader of the RFID system may sequentially power each antenna at a full power level and may further gradually decrease the power until none of the antennas from amongst the array of antennas read the tag. The approximate location of the tag can be identified from the location of the antenna that last read the tag, further details of which are described later in the description.

Further, in some example embodiments, the RFID system identifies the approximate location of the RFID tag in the area, by sequentially powering each antenna of an antenna array located in the area, over various frequency channels. In this regard, in some examples, the RFID system may determine the frequency channels based on a pre-defined rule. Further, in response to sequentially powering each antenna over the various frequency channels, the RFID system may gradually decrease the power of each antenna and continue to power antennas over various frequency channels. To this end, the RFID system computes a confidence score for each antenna which is used to identify the approximate location of the RFID tag in the area. The approximate location of the RFID tag is identified by determining the antenna with highest confidence value. The confidence value is determined based on read count, and in some example embodiments, weightage of respective read count, details of which are described later in the description.

By identifying an RFID tag and corresponding location associated with the RFID tag as described, embodiments eliminate the requirement that a user manually extensively search for such an RFID tag and/or corresponding asset. Additionally such RFID tags may be tracked as they transverse throughout an environment. Additionally still, particular aspects of embodiments described herein, such as the use of a plurality of power levels and/or frequency channels, increases the accuracy of the determinations described herein. Additionally other aspects, such as the use of confidence scores determined as described herein, further improve the accuracy of the determinations described herein. In this regard, the embodiments describe herein utilize particular, specially-configured computing system implementations to provide these technical improvements within the field of RFID tag identification and location determination.

<FIG> illustrates an exemplary environment <NUM> comprising a radio frequency identification (RFID) system <NUM>, according to one or more embodiments described herein. In some example embodiments, the environment <NUM> may correspond to an industrial environment (e.g., but not limited to, a warehouse, a distribution center, an inventory, a shipping center, a transport carrier, a lorry, a logistic vehicle, a material handling site, and/or the like). In some example embodiments, the RFID system <NUM> includes a server <NUM>, two or more antennas 106a, 106b, 106c. 106n (referred to as antennas <NUM> or array of antennas <NUM> interchangeably hereinafter for purpose of brevity), and one or more RFID readers 108a, 108b,. 108d (hereinafter referred to as RFID readers <NUM>). In an example embodiment, the antennas <NUM> and the RFID readers <NUM> can be communicatively coupled to the server <NUM>, through a network <NUM>.

In some examples, the antennas <NUM> and any of the RFID readers <NUM> may facilitate tracking of the assets <NUM> transiting through the environment <NUM>. In this regard, the assets <NUM> are associated with encoded RFID tags. In other words, in some examples, an RFID tag may be attached to each of the assets <NUM>. In some example embodiments, the antennas <NUM> may communicate to one or more components of an asset tracking system <NUM>. In some examples, the asset tracking system <NUM> may include any of the RFID readers <NUM> that may be used to interrogate encoded tags associated with assets for tracking the assets. In some examples, the RFID readers <NUM> can be handheld (e.g. a PDT device) that can be used by a worker <NUM>. In some examples, the asset tracking system <NUM> may include one or more fixed or standalone type RFID readers. In accordance with some example embodiments, the RFID readers <NUM> may output RF signals to interrogate RFID tags associated with the assets <NUM>. Any one or more of the RFID readers <NUM> may power the antennas <NUM> to interrogate RFID tags using RF signals. As illustrated, an RFID tag <NUM> may be associated with the asset <NUM>. In some examples, the RFID tag may store encoded data or data in original form that can be used to identify and/or track the asset <NUM>. In this regard, in some examples, to track the asset <NUM> in the RFID system <NUM>, a worker such as the worker <NUM> may utilize one of the RFID readers <NUM>, such as the RFID reader 108b, to retrieve the data from the tagged asset <NUM>.

According to some example embodiments, each of the RFID readers <NUM> may include suitable logic and/or circuitry that may enable the RFID readers <NUM> to retrieve the encoded data from the RFID tags (e.g. the RFID tag <NUM>) associated with the assets (e.g. the asset <NUM>). In some examples, the RFID tag <NUM> may store encoded data such as a card number, a product identifier, SKU number, and/or the like, associated with the asset <NUM>.

In some example embodiments, the antennas <NUM>, as illustrated in <FIG>, may correspond to a distributed antenna system that may be installed within the environment <NUM> (e.g. a warehouse). The distributed antenna system may represent a configuration of multiple antennas communicatively coupled via a communication circuitry, e.g. but not limited to, coaxial cables. Further, the antennas <NUM> in the distributed antenna system may be communicatively coupled to the RFID readers <NUM>. In some example embodiments, one or more of the antennas <NUM> of the distributed antenna system may be sequentially powered up by any of the RFID readers <NUM>. Further details of the distributed antenna system are described in reference to <FIG>.

In some example embodiments, the environment <NUM> may correspond to a warehouse, a storage location, or an inventory location where each antenna of the antennas <NUM> may be installed over a respective column of a storage location in the environment <NUM>. For instance, as illustrated, the environment <NUM> may include multiple columns (A, B, C. ) comprising portions of a plurality of shelves for storing the assets <NUM>. In this regard, each antenna may be configured to communicate interrogation signals received from the RFID readers <NUM> to interrogate RFID tags associated with such assets which can be located in the respective column. In some examples, the RFID system <NUM> may include smart switches that can use a coaxial cable for both transmitting RF signals and control signals to the antennas <NUM> connected over the coaxial cable. In some example embodiments, the distributed antenna system may include the antennas <NUM> arranged in an array so as to cover a defined area (e.g. columns) that may contain the assets <NUM> (e.g. packages/boxes). An example illustration of such a distributed antenna system is described in reference to <FIG>.

<FIG> illustrates an example apparatus implementation of one of the RFID readers <NUM>, according to one or more embodiments described herein. In an example embodiment, the example implementation of one of the RFID readers <NUM> can include a display screen <NUM>, an RFID reader antenna <NUM>, a trigger button <NUM>, and an antenna powering system <NUM>. In some examples, the display screen <NUM>, the RFID reader antenna <NUM>, and the antenna powering system <NUM> can be communicatively coupled with each other.

According to some example embodiments, the display screen <NUM> may include suitable logic, circuitry, interfaces, and/or code that may facilitate rendering or displaying of the content on the display screen <NUM>. In an example embodiment, the display screen <NUM> may be realized through several known technologies such as, Cathode Ray Tube (CRT) based display, Liquid Crystal Display (LCD), Light Emitting Diode (LED) based display, Organic LED display technology, and Retina display technology. In some embodiments, the display screen <NUM> may further include a touch panel, such as a thermal touch panel, a capacitive touch panel, and/or a resistive touch panel, which may enable the workers, such as worker <NUM>, to provide inputs to the implementation of the RFID readers <NUM>.

In some example embodiments, the RFID reader antenna <NUM> can correspond to an active element that may be configured to generate RF signals when a voltage signal is applied at the antenna element. For example, the RFID reader antenna may be configured to generate the RF signal in HF frequency band. In another example, the RFID reader antenna may generate the RF signal in the UHF frequency band. Some examples of the antenna <NUM> may include, but are not limited to, Bow tie antenna, dipole antenna, monopole antenna, loop antenna, and/or the like.

According to some example embodiments, the trigger button <NUM> may include suitable logic and/or circuitry that may facilitate the worker <NUM> to provide input to one or more of the RFID readers <NUM>, such as the RFID reader 108b. In an example embodiment, the trigger button <NUM> may either be an electro-mechanical button that may be configured to generate an electrical signal when the trigger button <NUM> is pressed. Further, the trigger button <NUM> may be communicatively coupled to the antenna powering system <NUM>. In some example embodiments, the trigger button <NUM> may be a touch-sensitive button, or a gesture-based button.

According to some example embodiments, the antenna powering system <NUM> included suitable logic and/or circuitry that enables the RFID readers <NUM> to enable powering on of the antennas <NUM>, as described in <FIG>. Further, the antenna powering system <NUM> may also control one or more operations of any one of the RFID readers <NUM> and/or the antennas <NUM>. The RFID readers <NUM> are configured to transmit, via the RFID reader antenna <NUM>, an interrogation signal to the RFID tag <NUM>.

<FIG> illustrates a block diagram of the example implementation of the RFID readers <NUM>, according to one or more embodiments described herein. The example implementation of the RFID readers <NUM> can include a processor <NUM>, a memory unit <NUM>, a communication interface <NUM>, an RFID reader unit <NUM>, an antenna powering unit <NUM>, a first antenna element <NUM>, and a second antenna element <NUM>.

In some example embodiments, the processor <NUM> may be embodied as means including one or more microprocessors with accompanying digital signal processor(s), one or more processor(s) without an accompanying digital signal processor, one or more coprocessors, one or more multi-core processors, one or more controllers, processing circuitry, one or more computers, various other processing elements including integrated circuits such as, for example, an application specific integrated circuit (ASIC) or field programmable gate array (FPGA), or some combination thereof. Accordingly, although illustrated in <FIG> as a single processor, in an embodiment, the processor <NUM> may include a plurality of processors and signal processing modules. The plurality of processors may be embodied on a single electronic device or may be distributed across a plurality of electronic devices collectively configured to function as the circuitry of the example implementation of the RFID readers <NUM>. In some examples, the plurality of processors may be in operative communication with each other and may be collectively configured to perform one or more functionalities of the circuitry of example implementation of the RFID readers <NUM>, as described herein. In an example embodiment, the processor <NUM> is configured to execute instructions stored in the memory unit <NUM> or otherwise accessible to the processor <NUM>. According to various example embodiments described herein, these instructions, when executed by the processor <NUM>, cause the circuitry of the example implementation of the RFID readers <NUM> to perform one or more of the functionalities, as described herein.

Whether configured by hardware, firmware/software methods, or by a combination thereof, the processor <NUM> includes an entity capable of performing operations according to embodiments of the present disclosure while configured accordingly. Thus, for example, when the processor <NUM> is embodied as an ASIC, FPGA or the like, the processor <NUM> includes specifically configured hardware for conducting one or more operations described herein. Alternatively, as another example, when the processor <NUM> is embodied as an executor of instructions, such as may be stored in the memory unit <NUM>, the instructions specifically configure the processor <NUM> to perform one or more algorithms and operations described herein.

Thus, the processor <NUM> used herein may refer to a programmable microprocessor, microcomputer or multiple processor chip or chips that can be configured by software instructions (applications) to perform a variety of functions, including the functions of the various embodiments described above. In some devices, multiple processors may be provided dedicated to wireless communication functions and one processor dedicated to running other applications. Software applications may be stored in the internal memory before they are accessed and loaded into the processors. The processors may include internal memory sufficient to store the application software instructions. In many devices, the internal memory may be a volatile or nonvolatile memory, such as flash memory, or a mixture of both. The memory can also be located internal to another computing resource (e.g., enabling computer readable instructions to be downloaded over the Internet or another wired or wireless connection).

The memory unit <NUM> includes suitable logic, circuitry, and/or interfaces that are adapted to store a set of instructions that is executable by the processor <NUM> to perform predetermined operations. Some of the commonly known memory implementations include, but are not limited to, a hard disk, random access memory, cache memory, read only memory (ROM), erasable programmable read-only memory (EPROM) & electrically erasable programmable read-only memory (EEPROM), flash memory, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, a compact disc read only memory (CD-ROM), digital versatile disc read only memory (DVD-ROM), an optical disc, circuitry configured to store information, or some combination thereof. In an example embodiment, the memory unit <NUM> may be integrated with the processor <NUM> on a single chip, without departing from the scope of the disclosure.

The communication interface <NUM> may correspond to an interface that may facilitate transmission and reception of messages and data to and from various components and/or devices. In some example embodiments, through the communication interface <NUM>, the antennas <NUM> of the RFID system <NUM> may be configured to communicate signals transmitted by the example implementation of the RFID readers <NUM>. In some examples, through the communication interface <NUM>, the antennas <NUM> may receive RF interrogation signals to interrogate the RFID tags <NUM> e.g., for tracking assets <NUM>. Examples of the communication interface <NUM> may include, but are not limited to, an antenna, an Ethernet port, a USB port, a serial port, or any other port that can be adapted to receive and transmit data. In some example embodiments, the communication interface <NUM> can transmit and receive data and/or messages in accordance with the various communication protocols, such as, I2C, TCP/IP, UDP, and <NUM>, <NUM>, and/or <NUM> communication protocols. In some example embodiments, the communication interface <NUM> may include suitable logic and/or circuitry that may be configured to communicate with the one or more components of the antennas <NUM>, in accordance with one or more device communication protocols such as, but not limited to, I2C communication protocol, Serial Peripheral Interface (SPI) communication protocol, Serial communication protocol, Control Area Network (CAN) communication protocol, and <NUM>-Wire® communication protocol.

In some example embodiments, the example implementation of the RFID readers <NUM> may include a signal processing unit (not shown) that may include suitable logic and/or circuitry for analyzing input signals received from one or more components. For example, the signal processing unit may include a digital signal processor that may be configured to identify peaks and valleys in the received signals. Further, the signal processing unit may utilize one or more signal processing techniques such as, but not limited to, Fast Fourier Transform (FFT), Discrete Fourier Transform (DFT), Discrete Time Fourier Transform (DTFT) to analyze the received signals. In some examples, the signal processing unit may be implemented using one or more hardware components, such as, but not limited to, FPGA, ASIC, and the like.

In accordance with some example embodiments, the first antenna element <NUM> and the second antenna element <NUM> of the example implementation of the RFID readers <NUM> may be configured to transmit/receive data by utilizing one or more of EPC global communication standards or DOD communication standards. In some example embodiments, the example implementation of the RFID readers <NUM> may include the RFID reader unit <NUM> that may comprise one or more of filters, analog to digital (A/D) converters, Digital to Analog (D/A) convertors, matching circuits, amplifiers, and/or tuners that can enable the RFID reader unit <NUM> to transmit interrogation commands for interrogating RFID tags <NUM>. Further, the RFID reader unit <NUM> may be configured to receive data over the one or more frequency bands through the first antenna element <NUM> and the second antenna element <NUM>. In some example embodiments, the RFID reader unit <NUM> may be implemented using one or more of Application Specific Integrated Circuit (ASIC) and Field Programmable Gate Array (FPGA).

According to some example embodiments described herein, the example implementation of the RFID readers <NUM> are configured to search (e.g. interrogate) for an RFID tag <NUM>. As described earlier, the RFID tag <NUM> is associated with the asset <NUM>. Further, the RFID tag can be interrogated by the example implementation of the RFID readers <NUM> for tracking the asset <NUM> in the environment <NUM>.

According to an example that does not embody the invention described herein, the processor <NUM> of the example implementation of the RFID readers <NUM> is configured to manipulate a transmit power at which the example implementation of the RFID readers <NUM> are configured to operate the antennas <NUM>. In other words, field strength at which the antennas <NUM> are operated by the example implementation of the RFID readers <NUM> can be varied or manipulated based on varying the transmitter output power of the example implementation of the RFID readers <NUM> coupled to the antenna. In an example which does not embody the invention, the processor <NUM> may be configured to initiate a binomial search operation to locate an antenna (i.e. from amongst the antennas <NUM>) that can be closest to the asset <NUM> to which the specific RFID tag is attached. In this regard, in some examples, the processor <NUM> may vary (e.g. increase or decrease) the transmit power of the example implementation of the RFID readers <NUM> while searching for a specific RFID tag, details of which are described hereinafter.

According to one example that does not embody the invention, the processor <NUM> may be configured to execute RF transmission by the example implementation of the RFID readers <NUM> within a power range, e.g. a maximum power level and a minimum power level, so as to vary the field strength at which the antennas <NUM> can be operated. In some examples, the maximum power level and the minimum power level may be user-defined. In an example embodiment, the processor <NUM> may initiate sending RF interrogation signals to search the RFID tags by sequentially powering one or more antenna from amongst the antennas <NUM> (i.e. array of antennas). In this regard, the RFID reader may power each antenna of the array of antennas <NUM>, one after another (i.e. one at a time), to interrogate the RFID tags. In some example embodiments, the example implementation of the RFID readers <NUM> may be configured initially to operate the antennas <NUM> at the maximum power level and may further gradually decrease the power level at which the antennas <NUM> are operated.

The example implementation of the RFID readers <NUM> that does not embody the invention, may execute the binomial search operation by initiating an identification of the RFID tag by operating the example implementation of the RFID readers <NUM> at the maximum power level. To this end, in some examples, if the RFID tag is identified by an antenna of the array of antennas <NUM>, then the processor <NUM> reduces the power level at which the example implementation of the RFID readers <NUM> operates the antennas <NUM>. In this regard, an identification of the RFID tag can be determined based on a signal (e.g., an acknowledgement) received at the antenna <NUM> in response to the interrogation command sent to the RFID tag. Further, at the reduced power level, the example implementation of the RFID readers <NUM> again operates the antennas <NUM> and interrogates the RFID tag. In this fashion, the processor <NUM> can sequentially power each antenna of the antennas <NUM> at a maximum or full power level and can gradually decrease the power until the RFID tag is not identified by any of the antennas. Furthermore, the processor <NUM> can identify the antenna which last read or identified the RFID tag before the transmit power at which the example implementation of the RFID readers <NUM> operates the antennas <NUM> is reduced to a value at which no RFID tag was identified. Furthermore, the processor <NUM> can utilize the identified antenna to identify the RFID tag and approximate the location of the asset to which the RFID tag is attached.

In some examples that do not embody the invention, in response to identification of the RFID tag, the processor <NUM> can be configured to reduce the power level at which the antennas <NUM> are operated based on following equation (i.e. Equation <NUM>): <MAT>.

Accordingly, the processor <NUM> can repeat reducing the transmit power level at which the antenna <NUM> is operated using the Equation <NUM>, until the RFID tag is not identified. However, in an instance, when the example implementation of the RFID readers <NUM> fails to find the RFID tag, the processor <NUM> can increase the transmit power level. In this regard, the processor <NUM> can compute a next power level at which the example implementation of the RFID readers <NUM> operates the antenna <NUM> based on below equation (i.e. Equation <NUM>): <MAT>.

Accordingly, in some example embodiments that do not embody the invention, the processor <NUM> can continue alternating the transmit power levels between decreasing power and increasing power until it runs out of power levels, to identify the RFID tags. An example operation of the RFID system <NUM> to identify the RFID tag is described in following paragraphs.

In an example embodiment that does not embody the invention, the example implementation of the RFID readers <NUM> can be configured to operate at a maximum power level of 30dB and a minimum power level of 20dB. In this regard, at step <NUM>, the processor <NUM> can configure the example implementation of the RFID readers <NUM> to operate at the maximum power level i.e. 30dB and send interrogation command to read the RFID tag. At step <NUM>, if the RFID tag is identified, the processor <NUM> can determine a next power setting as 5dB (i.e. (<NUM>-<NUM>)/<NUM>) and a next power level as <NUM> dB (i.e. <NUM>-<NUM>). Further, at step <NUM>, the processor <NUM> can configure the example implementation of the RFID readers <NUM> to operate at the next power level i.e. <NUM> dB. At step <NUM>, if the RFID tag is identified, the processor <NUM> can again reduce the transmit power level by determine the next power level based on the Equation <NUM>, as described earlier. In this regard, the processor <NUM> can determine the next power level as <NUM> dB (i.e. (<NUM>-<NUM>)/<NUM> = <NUM> (round down or up) which can be round down to 2db; next power level = <NUM>+<NUM>=22db). Further, at step <NUM>, if the RFID tag is not identified, the processor <NUM> can increase the transmit power level. In this regard, the processor <NUM> can determine a next power level based on the Equation <NUM>, as described earlier. Accordingly, at step <NUM>, the processor <NUM> can determine a next power level to be <NUM> dB (i.e. (<NUM>-<NUM>)/<NUM> = <NUM> (round up or down) for this example round down to 2db; (<NUM> dB - <NUM> dB) = <NUM> Db. In one example that does not embody the invention, the process of increasing and/or decreasing the transmit power level can be repeated until, an antenna which last read the RFID tag (before no RFID tag identification) is identified. Furthermore, the processor <NUM> can use the identified antenna to locate the RFID tag.

According to an embodiment of the present invention, the processor <NUM> is configured to compute a confidence score corresponding to each antenna of the array of antennas <NUM>. In this regard, the processor <NUM> utilizes the confidence score to identify the antenna closest to the RFID tag searched by the example implementation of the RFID readers <NUM>. Further, the processor <NUM> can identify the RFID tag searched by the example implementation of the RFID readers <NUM> based on the antenna identified using the confidence score. In an example embodiment, the processor <NUM> can be configured to sequentially power each antenna at maximum power over various frequency channels. In this regard, the frequency channels can be selected by the processor <NUM> based on a predefined rule. In some examples, the predefined rule includes use of frequency dwell time associated with each antenna. In some examples, a frequency hopping time (i.e. a time to hop to a next frequency channel) can be modified based on the frequency dwell time associated with the antenna. Further, processor <NUM> can be configured to repeat steps of the sequential powering of the antennas based on decreasing the transmit power level over the various frequency channels. According to said example embodiment, the processor <NUM> records a number of RFID tag reads received by each antenna at various power levels and various frequency channels (the number of tag reads at each frequency for a power level representing a sub-count of the number of tag reads in total). In this regard, in some example embodiments, the processor <NUM> utilizes a read signal received at the antenna and/or the example implementation of the RFID readers <NUM>, in response to the interrogation command, to determine an identifier of the RFID tag and increase a count for that RFID tag and for that antenna. Further, the processor <NUM> can compute the confidence score by adding a weightage parameter to the number of RFID tag reads at each antenna. The weightage parameter can be based on a transmit power intensity associated with the example implementation of the RFID readers <NUM>. Furthermore, the processor <NUM> utilizes the confidence score to determine an approximate location of the RFID tag searched by the example implementation of the RFID readers <NUM>. Following paragraph describes an example illustration of computation of the confidence score by the processor <NUM> of the example implementation of the RFID readers <NUM> to locate the RFID tag.

In an example, the processor <NUM> may compute a confidence score of each antenna based on below equation: <MAT>.

Here p1, p2, p3 each represent a weightage parameter applicable according to a transmit power level selected for a round of antenna operation. The weightage parameter is indicative of a weightage given to values (i.e. number of RFID tag reads) recorded at the respective antenna. For instance, p1 represents a first weightage parameter applicable for a first transmit power level of 20dBm, p2 represents a second weightage parameter applicable for a second transmit power level of 15dBm, and p3 represents a third weightage parameter applicable for a third transmit power level of <NUM> dBm. In some example embodiments, the weightage parameter can be inversely proportional to the transmit power level. In an example, the first weightage parameter p1 can be <NUM>, the second weightage parameter p2 can be <NUM>, and the third weightage parameter p3 can be <NUM>. Further, N20dBm represents a number of RFID tag reads recorded at the antenna when the antenna is operated at the transmit power level 20dBm of the example implementation of the RFID readers <NUM>. Similarly, N15dBm represents a number of RFID tag reads received at the antenna when the antenna is operated at the transmit power level 15dBm of the example implementation of the RFID readers <NUM>. Below table illustrates an example of number of RFID tag reads received at a first antenna (i.e. Antenna <NUM>) and a second antenna (i.e. Antenna <NUM>) from amongst the array of antennas <NUM> at varying transmit power level and various frequency channels:.

Here frequency f1, f15, f3, f12. f23 can be randomly determined by the processor <NUM> based on the predefined rule. In the above example, the processor <NUM> may compute the confidence score of the antennas as stated below: <MAT> <MAT>.

As the confidence score of Antenna <NUM> is greater than the confidence score of Antenna <NUM>, the processor <NUM> may accordingly identify the Antenna <NUM> to be closest to the RFID tag searched by the RFID readers <NUM>.

By way of implementation of the example embodiment described herein, the example implementation of the RFID readers <NUM> may effectively locate a desired RFID tag in a confined area. In this aspect, by utilizing spatial, frequency and temporal diversity in combination and performing weighted data analysis to compute the confidence score of each antenna, as described earlier, RFID tags attached to assets can be accurately tracked even in presence of reflections and noise due to metallic surfaces in the environment.

According to an example embodiment, the example implementation of the RFID readers <NUM> can be configured to keep a track of a time spent on a frequency channel when a radio transmitter of the example implementation of the RFID readers <NUM> is turned ON. Further, in some example embodiments, the processor <NUM> of the example implementation of the RFID readers <NUM> can be configured to automatically switch to a new frequency channel based on the pre-defined rule to operate the antenna over the new frequency channel. In some examples, the new frequency channel can be identified based on a pseudorandom sequence if the time monitored by the processor <NUM> exceeds a frequency dwell time. In some example embodiments, the processor <NUM> may also switch to power a next antenna if the frequency dwell time associated with a previous antenna is exceeded.

<FIG> illustrates an RFID system <NUM> comprising the example implementation of the RFID readers <NUM> and a plurality of antennas (<NUM>) in a distributed antenna network, according to one or more example embodiments described herein. As illustrated, each antenna of the plurality of antennas can be communicatively coupled to the example implementation of the RFID readers <NUM>. In some examples, the RFID system <NUM> may include smart switches (402a, 402b, 402c. 402n) that can be controlled using RF signals by the example implementation of the RFID readers <NUM>. The smart switches (402a, 402b, 402c. 402n) can connect the example implementation of the RFID readers <NUM> via the coaxial cable to the antennas <NUM>. In some example embodiments, the smart switches can be configured for both transmitting RF signals and control signals to the antennas <NUM> connected over the coaxial cable. In some example embodiments, the example implementation of the RFID readers <NUM> can be configured to selectively switch one or more of the smart switches (402a, 402b, 402c. 402n) to connect the example implementation of the RFID readers <NUM> with an antenna connected with the selected switch. Accordingly, the example implementation of the RFID readers <NUM> can communicate with the RFID tag <NUM> using RF signals and obtain data from the RFID tag <NUM>.

In some example embodiments, each of the smart switches can include a switching element, such as a switch, more particularly an RF switch that can be controllable to switch between two output states. In an example embodiment, the smart switch can include an RF coupler, an RF switch, and a RF Integrated circuit (IC). In an example, the RFID IC of the smart switch can be an EM4325 Gen <NUM> IC with a Serial Peripheral Interface (SPI) that outputs signal to switch the RF switch. In an example, the RF switch can be a pseudomorphic high-electron-mobility transistor (pHEMT) gallium arsenide (GaAs) switch. In this regard, in an example operation of the switch, control signals may be transmitted to the switch and received by the RFID IC, such that the RFID IC operates as an RF front end and protocol handler for communication with one or more RFID tags <NUM> described herein. Thus, this configuration allows for the smart switches (402a, 402b, 402c. 402n) to be switched between a connected and through states, such that an antenna coupled with a connected switch can be activated, thereby allowing communication (e.g., communication with one or RFID tags using RFID communication protocols). According to some example embodiments, the distributed antenna system as described herein, can be implemented based on techniques as described in U. Patent Application no <CIT>.

In some example embodiments, the distributed antenna system may include the antennas <NUM> arranged in an array so as to cover a defined area (e.g. columns) that may contain the assets <NUM> (e.g. packages/boxes). In some example embodiments, each antenna of the distributed antenna network may be installed over a defined area of an environment. For instance, in some examples, in a warehouse or inventory storage environment, each antenna of may be installed over a respective column (A, B, C. N) of a storage location of the warehouse. Further, each antenna may be configured to communicate interrogation signals received from the example implementation of the RFID readers <NUM> to interrogate an RFID tag <NUM> that can be associated with the asset <NUM> located in the respective column.

<FIG> illustrates an example flowchart representing a method <NUM> of identifying an RFID tag, in accordance with some example embodiments described herein.

In accordance with various example embodiments described herein, it will be understood that each block of the flowcharts, and combinations of blocks in the flowcharts, may be implemented by various means, such as hardware, firmware, one or more processors, circuitry and/or other devices associated with execution of software including one or more computer program instructions. For example, one or more of the procedures described above may be embodied by computer program instructions. In this regard, the computer program instructions which embody the procedures described above may be stored by a memory of an apparatus employing an embodiment of the present invention and executed by a processor in the apparatus. As will be appreciated, any such computer program instructions may be loaded onto a computer or other programmable apparatus (e.g., hardware) to produce a machine, such that the resulting computer or other programmable apparatus provides for the implementation of the functions specified in the flowcharts' block(s). These computer program instructions may also be stored in a non-transitory computer-readable storage memory that may direct a computer or other programmable apparatus to function in a particular manner, such that the instructions stored in the computer-readable storage memory produce an article of manufacture, the execution of which implements the function specified in the flowcharts' block(s). The computer program instructions may also be loaded onto a computer or other programmable apparatus to cause a series of operations to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide operations for implementing the functions specified in the flowcharts' block(s). As such, the operations of <FIG>, when executed, convert the computer or processing circuitry into a particular machine configured to perform an example embodiment of the present invention. Accordingly, the operations of <FIG> can define an algorithm for configuring a computer or processor, to perform an example embodiment. In some cases, a general-purpose computer may be provided with an instance of the processor which performs the algorithm of <FIG> to transform the general-purpose computer into a particular machine configured to perform an example embodiment.

Accordingly, blocks of the flowchart support combinations of means for performing the specified functions and combinations of operations for performing the specified functions. It will also be understood that one or more blocks of the flowcharts, and combinations of blocks in the flowchart, can be implemented by special purpose hardware-based computer systems which perform the specified functions, or combinations of special purpose hardware and computer instructions.

The method <NUM> starts at step <NUM>. At step <NUM>, the RFID system <NUM> may include means such as, the processor <NUM> of the RFID reader to start a new inventory search. In this regard, the processor <NUM> initiates sending of an interrogation command (e.g. RF Tag interrogation signals) to interrogate an RF tag. As described earlier, the RF tag may be associated with an asset stored in the inventory, which is to be searched by the example implementation of the RFID readers <NUM>. In an example embodiment, the example implementation of the RFID readers <NUM> may be operated at a maximum transmit power level or a predefined transmit power level to initiate the inventory search. Further, in some examples, the processor <NUM> may operate the antennas at the maximum or predefined transmit power level. Further, as described earlier, the processor <NUM> may identify one or more antennas from amongst the array of antennas which received an acknowledgement from the RF tag in response to the interrogation command.

At step <NUM>, the processor <NUM> checks for getting (i.e. determining) a next power level. In this aspect, as described earlier, in some example embodiments, the processor <NUM> of the example implementation of the RFID readers <NUM> may be configured to increase or decrease a transmit power level at which the example implementation of the RFID readers <NUM> operates the antennas <NUM>. Accordingly, at step <NUM>, the processor <NUM> may identify a next power level (e.g. by using the Equation <NUM> or the Equation <NUM>, as described earlier) to operate the antennas <NUM> by the example implementation of the RFID readers <NUM>. In an instance, if the processor <NUM> gets a next power level, the method <NUM> can move to step <NUM>. Alternatively, if the processor <NUM> fails to get a next power level (e.g. a minimum or maximum transmit power level is reached) the method <NUM> can move back to step <NUM> at which the processor <NUM> initiates a search for a next inventory (i.e. a next RF tag).

At step <NUM>, the processor <NUM> operates one or more antennas of the array of antennas <NUM> at the transmit power level identified at the step <NUM>. In this regard, in an instance, when each antenna of the array of antenna is operated at the transmit power level identified at step <NUM>, and the processor <NUM> can identify a next transmit power level at step <NUM>. Otherwise, the processor <NUM> can continue to power each antenna until an antenna timeout is reached at step <NUM>. As described earlier, to operate the antennas <NUM>, the processor <NUM> can sequentially power each antenna of the array of antennas <NUM> using the transmit power level identified at step <NUM>.

According to some example embodiments described herein, the processor <NUM> can identify the antenna time out at step <NUM>, based on using a frequency dwell time associated with each antenna. In this regard, each antenna of the array of antennas <NUM> can be configured to be operated within a frequency range related to the frequency dwell time. In other words, as described earlier, the processor <NUM> can keep a track of a time that is spent on a frequency when a radio transmitter of the example implementation of the RFID readers <NUM> is turned ON (i.e. a time during which the example implementation of the RFID readers <NUM> operates the antennas <NUM>). Further, the processor <NUM> can be configured to automatically switch to a new frequency channel based on a pseudorandom sequence (e.g. if the time exceeds a frequency dwell time associated with the respective antenna <NUM>).

Accordingly, at step <NUM>, if the processor <NUM> identifies the antenna time out, the method <NUM> moves back to the step <NUM> at which the processor <NUM> identifies a next antenna that can be powered by the example implementation of the RFID readers <NUM>. However, if the antenna time out is not reached, the method <NUM> moves to step <NUM> at which the processor <NUM> can cause the example implementation of the RFID readers <NUM> to transmit RF signals (i.e. interrogation command) at a current frequency identified based on the predefined rule. Further, at step <NUM>, the processor <NUM> determines if an RFID tag is read (i.e. an acknowledgement signal is received at the antenna in response to the interrogation command). In this regard, if the RFID tag is not read at step <NUM>, the processor <NUM> operates a next antenna at a same transmit power level and/or based on a different frequency channel. Otherwise, in response to reading of the RF tag at step <NUM>, the processor <NUM> updates a tag location by identifying the antenna at which the RF tag is read. In other words, at step <NUM>, the processor <NUM> records and/or updates a count of RF tag read by the antenna when the antenna is operated at a current frequency channel and a current transmit power. It should be appreciated that the described process for updating the tag location may be repeated any number of times, for example to track movement of the RFID tag as it transverses within a particular environment (e.g., a warehouse) over time.

In some example embodiments, identification of the RF tag associated with the asset can include identification of a location of the antenna closest to the RF tag. In this regard, the processor <NUM> can calculate the location of the antenna based on the transmit power and frequency on the antenna that is used to read the tag. Further, as described earlier, according to the invention, the location is computed based on estimating a confidence score based on the number of times the tag is read on an antenna and weights associated with the power and/or the frequency used. In some embodiments, each frequency channel is associated with a particular weightage parameter, and/or each power transmit level is associated with a particular weightage parameter. In other example embodiments, upon identifying the location of the antenna, a location of the RF tag can also be determined based on triangulation techniques e.g. triangulating the RF tag based on the signals received from the tag by the antennas <NUM> in the array.

In some example embodiments, one or more antennas of the array of antennas <NUM> can be associated with an indicator element (e.g. a light indicator, a sound indicator, etc.) which can be actuated in response to identification of the antenna by the processor <NUM>. In other words, in some example embodiments, an indicator associated with the antenna can be actuated to indicate which antenna is closest to the RF tag being searched by the example implementation of the RFID readers <NUM>.

The hardware used to implement the various illustrative logics, logical blocks, modules, and circuits described in connection with the aspects disclosed herein may include a general purpose processor, a digital signal processor (DSP), a special-purpose processor such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA), a programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but, in the alternative, the processor <NUM> may be any processor, controller, or state machine. A processor <NUM> may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. Alternatively, or in addition, some steps or methods may be performed by circuitry that is specific to a given function.

In one or more example embodiments, the functions described herein may be implemented by special-purpose hardware or a combination of hardware programmed by firmware or other software. In implementations relying on firmware or other software, the functions may be performed as a result of execution of one or more instructions stored on one or more non-transitory computer-readable media and/or one or more non-transitory processor <NUM>-readable media. These instructions may be embodied by one or more processor <NUM>-executable software modules that reside on the one or more non-transitory computer-readable or processor <NUM>-readable storage media. Non-transitory computer-readable or processor <NUM>-readable storage media may in this regard comprise any storage media that may be accessed by a computer or a processor <NUM>. By way of example but not limitation, such non-transitory computer-readable or processor <NUM>-readable media may include RAM, ROM, EEPROM, FLASH memory, disk storage, magnetic storage devices, or the like. Disk storage, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc™, or other storage devices that store data magnetically or optically with lasers. Combinations of the above types of media are also included within the scope of the terms non-transitory computer-readable and processor <NUM>-readable media. Additionally, any combination of instructions stored on the one or more non-transitory processor <NUM>-readable or computer-readable media may be referred to herein as a computer program product.

Claim 1:
A method comprising:
initiating an interrogation command associated with an RFID tag (<NUM>);
causing activation of a plurality of antennas (<NUM>) at a plurality of transmit power levels over a plurality of frequency channels;
identifying a count of tag reads associated with each antenna of the plurality of antennas, wherein the count of tag reads associated with each antenna of the plurality of antennas comprises sub-counts of tag reads, wherein each sub-count is associated with frequency channels of the plurality of frequency channels for a transmit power level of the plurality of transmit power levels;
generating a plurality of confidence scores comprising a confidence score for each antenna based at least in part on the sub-counts of tag reads associated with each antenna; and
determining a tag location associated with the RFID tag based at least in part on the plurality of confidence scores, wherein the tag location associated with the RFID tag is determined by determining at least one antenna of the plurality of antennas with a highest confidence score.