Patent Description:
Generally, RFID methods are used for the identification of goods and persons in a wide variety of applications, for example, for the purpose of real-time inventory of goods in retail and industrial environments, as well as for access control to facilities and the like. In many applications, an RFID tag is used in combination with an RFID reader, which reader is configured to read information provided on the tag. To this end, the RFID reader outputs an RFID signal to one or more antennas, and the antennas emit the RFID signal towards the RFID tag.

The present disclosure is directed, at least in part, to improving or overcoming one or more aspects of prior systems.

The present disclosure relates to a system for reading RFID tags according to claim <NUM>. The system comprises an RFID reader configured to output at least one RFID signal, at least one booster module configured to receive the at least one RFID signal, and a system controller configured to output a control signal for the at least one booster module. The at least one booster module includes a module controller configured to receive the control signal, a power amplifier configured to amplify at least a reduced power portion of the received RFID signal, and at least one booster antenna configured to emit the amplified RFID signal.

Other features and aspects of the present disclosure will be apparent from the following description and the accompanying drawings.

The following is a detailed description of exemplary embodiments of the present disclosure. The exemplary embodiments described herein are intended to teach the principles of the present disclosure, enabling those of ordinary skill in the art to implement and use the present disclosure in many different environments and for many different applications. Therefore, the exemplary embodiments are not intended to be, and should not be considered as, a limiting description of the scope of protection. Rather, the scope of protection shall be defined by the appended claims.

The present disclosure is based at least in part on the realization that an accurate real-time inventory of static articles, for example, in large storage areas is challenging when RFID technology is used. It has been realized that a simple scaling of the system using a plurality of additional RFID readers, each connected to a plurality of antennas, is prohibitively expensive. Further, it introduces problems impacting the overall performance, such as mutual jamming of readers that operate in close proximity to each other. Therefore, it has been realized that a cost-effective solution is to use existing RFID readers, and provide add-ons in the form of additional booster modules with additional antennas and a dedicated power supply to increase the number of transmitting and/or reading antennas in the system. In this manner, the number of readers used can be limited, and the jamming problems mentioned above can be overcome.

In addition, it has been realized that, by using the above-mentioned booster modules, a power output by the one or more RFID readers can be reduced, as the output signal can be amplified by each of the booster modules. This can increase the read sensitivity of the respective RFID readers. This allows for a further performance improvement, and/or the use of less complex, more cost-effective readers.

In addition, it has been realized that the booster modules can be connected in series to a given RFID reader, each using a portion of the power of the RFID signal output by the reader. In this respect, it has also been realized that the RFID signal, the power supply signal, and the control signal for each booster module can be multiplexed and transmitted on a single cable connection. The above two aspects greatly reduce the complexity associated with connecting the respective booster modules and their antennas to the RFID reader, resulting in reduced installation costs.

Additionally, it has been realized that, using the above-mentioned booster modules, the number of transmitting spots, as well as the phase and frequency diversity can be increased. This can not only improve the read performance, but also improve the location accuracy. In particular, it has been realized that different booster modules may be controlled to simultaneously use different frequency bands or channels, for example, when allowed by applicable local regulations. In ETSI-regulated regions, for example, the <NUM> channels of the ETSI lower band and/or the <NUM> channels of the ETSI upper band can be simultaneously used. This may also result in an increased total power that can be output in the different frequency ranges.

Further, it has been realized that the provision of a plurality of antennas for a single booster module also increases the flexibility with respect to beam forming and other aspects relating to signal transmission. In particular, variable phases can be used at each transmission node to avoid destructive interferences. Beam forming further improves the localization accuracy.

One additional advantage that has been realized is that each booster module can also be used as a receiving device, in accordance with a control performed by a module controller included in the booster module and controlled in accordance with a received control signal.

Finally, it has been realized that the system of the present disclosure is not only useful in determining real time static or dynamic inventory, but can also be used in other applications in which, for example, a large number of passive tags are present in a limited space, even if the space is shielded from electromagnetic radiation to some extent. Further, it has also been realized that the disclosed system can be used to provide access control and monitor attendance at facilities, for example, in stadium entry and/or exit portals or the like. This is especially useful for controlling access of a large number of people simultaneously crossing a checkpoint or the like. In particular, the improved performance helps mitigating the absorption problems due to absorption of UHF energy by human bodies.

<FIG> shows an exemplary embodiment of a system <NUM> for reading RFID tags <NUM>. As shown in <FIG>, system <NUM> includes an RFID reader <NUM> configured to output at least one RFID signal <NUM>, at least one booster module <NUM> configured to receive the at least one RFID signal <NUM>, and a system controller <NUM> configured to output a control signal <NUM> for the at least one booster module <NUM>.

RFID reader <NUM> can be any commonly used RFID reader, which can output an RFID signal for reading RFID tags <NUM> in a known manner. In one exemplary embodiment, RFID tags <NUM> are passive RFID tags, which are read by RFID reader <NUM> in a known manner. In some embodiments, RFID signal <NUM> is a ultra-high frequency (UHF) RFID signal. In some embodiments, semi-active and/or active RFID tags, and/or different frequency ranges can be used. It will be appreciated that RFID reader <NUM> may have a plurality of outputs (not shown) for outputting RIFD signal <NUM> either in parallel or via a selected one of said outputs.

Commonly, RFID signal <NUM> output by RFID reader <NUM> is supplied to a reader antenna <NUM> directly connected to a corresponding output of RFID reader <NUM>. In accordance with the present disclosure, however, RFID signal <NUM> is input to booster module <NUM>, which will be described in more detail below.

Booster module <NUM> includes a module controller <NUM> configured to receive control signal <NUM>, a power amplifier <NUM> configured to amplify at least a reduced power portion of the received RFID signal <NUM>, and at least one booster antenna <NUM> configured to emit the amplified RFID signal <NUM>. As used herein, "reduced power portion of the RFID signal" indicates that an RFID signal <NUM> output by RFID reader <NUM> has a first power (for example, measured in dBm), and that booster module <NUM> includes a power divider or splitter that generates a reduced power RFID signal from RFID signal <NUM> for further processing by booster module <NUM>. Such power dividers or splitters are known, such that a detailed description will be omitted. In some embodiments, in particular, when a single booster module <NUM> is connected to each output of RFID reader <NUM>, and no further antennas are provided, it is also contemplated that RFID signal <NUM> output by RFID reader <NUM> is already a reduced power signal (i.e., having a second power that is considerably less than the first power mentioned above). In this case, a power divider or splitter may not be provided in booster module <NUM>, or may be deactivated, and the signal that is amplified is the signal that is output by the reader.

In case a plurality of booster modules are connected in series to RFID reader <NUM>, booster module <NUM> includes a signal output <NUM> configured to output a remaining power portion of the received RFID signal <NUM>. Optionally, output <NUM> may also be configured to output the received control signal <NUM> to another booster module <NUM> having an identical configuration. In this manner, a so-called "daisy chain" of booster modules can be connected to each reader output. In some cases, as shown in <FIG>, at the end of such a daisy chain, a conventional reader antenna <NUM> may be provided, which receives the remaining power portion of the RFID signal <NUM> output by the last booster module <NUM>.

In the simplest case, for example, only a single booster module <NUM> may be connected to each reader output, and the remaining power portion of RFID signal <NUM> may be output from booster module <NUM> to reader antenna <NUM>. In such a configuration, the total number of antennas is increased by the total number of booster antennas <NUM> provided in the respective booster modules <NUM>. Also in this case, it will be appreciated that a plurality of booster modules <NUM> may be connected in parallel to the respective outputs of RFID reader <NUM>. In an exemplary embodiment, for example, RFID reader <NUM> includes four outputs, and to each output one booster module <NUM> is connected. Each booster module <NUM> may include, for example, four booster antennas <NUM>, and be further connected to one reader antenna <NUM>. Therefore, the total number of antennas can be increased by a factor of five, from four to twenty. It will be appreciated, however, that this is just an example, and any desired number of booster modules <NUM> can be connected in series or in parallel to RFID reader <NUM>.

In order for booster module <NUM> to be capable of amplifying RFID signal <NUM>, a power signal <NUM> for supplying power to at least one booster module <NUM> has to be provided. As shown in <FIG>, power signal <NUM> may be generated by a power controller <NUM> of system <NUM>. In the exemplary embodiment shown in <FIG>, power signal <NUM> is output from power controller <NUM> to a mixer <NUM> of system <NUM>. Mixer <NUM> is configured to generate a combined signal <NUM> including power signal <NUM> and RFID signal <NUM>, and to output combined signal <NUM> to at least one booster module <NUM>. It will be appreciated from the above that, in accordance with the present disclosure, RFID signal <NUM> output from RFID reader <NUM> does not necessarily have to be directly input into booster module <NUM>. Instead, it can be included in combined signal <NUM>, and combined signal <NUM> may be input to booster module <NUM>. However, this should still be considered as inputting RFID signal <NUM> into booster module <NUM>.

In the exemplary embodiment shown in <FIG>, mixer <NUM> also receives control signal <NUM> from system controller <NUM>, to generate a multiplexed combined signal <NUM> including power signal <NUM>, control signal <NUM> and RFID signal <NUM>. It will be appreciated, however, that in other embodiments mixer <NUM> may be configured to generate a combined signal <NUM> including at least two of power signal <NUM>, control signal <NUM> and RFID signal <NUM>.

In order to process combined signal <NUM>, booster module <NUM> includes a splitter <NUM> configured to extract the at least two of power signal <NUM>, control signal <NUM> and RFID signal <NUM> from combined signal <NUM>. The multiplexing and de-multiplexing (splitting) of signals is well-known, such that the details will be omitted herein. It will be appreciated, however, that booster module <NUM> includes an appropriate splitter <NUM> that can extract the different components of combined signal <NUM>, in particular, RFID signal <NUM>. In some embodiments, it is also contemplated that RFID signal <NUM> is not part of combined signal <NUM>, and that combined signal <NUM> only includes control signal <NUM> and power signal <NUM>. In that case, splitter <NUM> will be configured accordingly to extract control signal <NUM> and power signal <NUM>. Power signal <NUM> is used to operate the different components of booster module <NUM>, in particular, power amplifier <NUM> and module controller <NUM>. For example, mixer <NUM> may output an appropriate DC voltage for operating power amplifier <NUM> and module controller <NUM>. Of course, it will also be appreciated that different electronic components may be included to provide different voltages and the like for different components, where appropriate.

From the above, it will also be appreciated that the at least one booster module <NUM> is configured to output combined signal <NUM> after extraction of the reduced power portion of RFID signal <NUM> to another booster module <NUM> having an identical configuration. In other words, for example, when combined signal <NUM> includes RFID signal <NUM>, control signal <NUM> and power signal <NUM>, splitter <NUM>, which may also include a power divider for generating the reduced power portion of RFID signal <NUM>, may also be configured to generate a new combined signal <NUM> including the remaining power portion of RFID signal <NUM>, power signal <NUM> and control signal <NUM>, which can then be output to another booster module <NUM> to allow for the above-described serial connection of a plurality of booster modules <NUM>.

Using mixer <NUM> to generate combined signal <NUM> allows for inputting combined signal <NUM> to the at least one booster module <NUM> via a single cable connection <NUM>, for example, an Ethernet cable, a coaxial cable or a USB cable. In some embodiments, RFID signal <NUM> may be input to booster module <NUM> via a separate coaxial cable, and combined signal <NUM> including power signal <NUM> and control signal <NUM> may be input to booster module <NUM> via an Ethernet cable or a USB cable in a known manner.

During an exemplary operation of the embodiment shown in <FIG>, system controller <NUM> controls RFID reader <NUM>, power controller <NUM> and mixer <NUM> to generate combined signal <NUM> including power signal <NUM>, control signal <NUM> and RFID signal <NUM>, and output the same to a first booster module <NUM>. Splitter <NUM> of booster module <NUM> extracts the individual signal components and forwards control signal <NUM> to module controller <NUM>. In addition, power signal <NUM> is provided to the internal power supply circuitry of booster module <NUM> to generate the necessary operation voltages. The reduced power portion of RFID signal <NUM> is forwarded to power amplifier <NUM> to amplify the same, and amplified RFID signal <NUM> is provided to at least one booster antenna <NUM> to emit the amplified RFID signal. In this respect, it will be appreciated that module controller <NUM> is configured to selectively operate the at least one booster antenna <NUM> in a transmitting mode and a receiving mode based on control signal <NUM>. In other words, the above-described amplification of RFID signal <NUM> is performed in the transmitting mode. On the other hand, in the receiving mode, RFID signal <NUM>, or a slightly reduced power RFID signal <NUM> (in case the remaining power RFID signal is to be forwarded to a further booster module for amplification) is forwarded to at least one booster antenna <NUM> without amplification. Likewise, the received signal is forwarded from at least one booster antenna <NUM> to RFID reader <NUM> via connection <NUM>. Here, it will be appreciated that, in the receiving mode, various components used in the transmitting mode may be bypassed (for example, splitter <NUM> and mixer <NUM>) when the received signal is forwarded to RFID reader <NUM>.

Regardless of which mode is used, the remaining power RFID signal is output to one or more additional booster modules <NUM>, which again process said signal in the above-described manner. In the context of operating booster module <NUM> in different modes, it will be appreciated that one or more routing units <NUM>, <NUM> may be provided. For example, a pre-routing unit <NUM> and a post-routing unit <NUM> may be provided upstream and downstream of power amplifier <NUM> to allow for selectively passing RFID signal <NUM> to power amplifier <NUM> or directly to booster antenna <NUM>. Pre-routing units <NUM>, <NUM> are controlled by module controller <NUM> in accordance with control signal <NUM>.

As shown in <FIG>, in some embodiments, booster module <NUM> further includes a modulator <NUM> (for example, a vector modulator VM) configured to modify the phase of RFID signal <NUM> prior to amplification by power amplifier <NUM>. Optionally, a variable gain amplifier (VGA) <NUM> may be provided, which is configured to pre-amplify the RFID signal <NUM> that is input to modulator <NUM>. Here, VGA <NUM> may be configured to pre-amplify RFID signal <NUM> such that downstream components such as power amplifier <NUM> can operate in their specific input ranges. Further, VGA <NUM> may be configured to control the final power output provided by power amplifier <NUM> in case power amplifier <NUM> does not include output power control.

As shown in <FIG>, booster module <NUM> may further include a frequency converter (for example, an up-converter UC) <NUM> configured to shift a frequency of RFID signal <NUM> prior to amplification by power amplifier <NUM>. For example, frequency converter <NUM> may be configured to shift the frequency of RFID signal <NUM> between a range from about <NUM> to <NUM> (ETSI lower band) and a range of about <NUM> to <NUM> (ETSI upper band), or from a channel to another channel within the same band (for example, from channel <NUM> of the FCC band to channel <NUM> of the same band). Further, a total power received at an RFID tag can be increased, due to both signals simultaneously being received at RFID tag <NUM>, for example, with a combined radiated power of 6W ERP (2W ERP in the first band and 4W ERP in the second band). System controller <NUM> and/or module controller <NUM> may be configured to dynamically change the use of the different bands/channels by booster modules <NUM> during operation. Here, it will be appreciated that, in other embodiments, one or more of modulator <NUM>, variable gain amplifier <NUM> and frequency converter <NUM> may be omitted, if desired.

As previously mentioned, booster module <NUM> may include a plurality of booster antennas <NUM>, for example, two to eight, preferably four, booster antennas <NUM>, and routing module <NUM> is configured to selectively provide the amplified RFID signal to one or more of the plurality of booster antennas <NUM> in accordance with control signal <NUM> processed by module controller <NUM>. It will be appreciated that, although booster antennas <NUM> are shown as part of the same functional block as the other components of booster module <NUM>, in practice, it is not required that booster antennas <NUM> are integrated into a single PCB or housing with the remaining components. For example, booster antennas <NUM> may be separate members (for example, wire antennas) connected to the other components of booster module <NUM> in an appropriate manner. By an appropriate control, one or more of booster modules <NUM> may be configured to emit beams with a desired direction to reduce destructive interference or create zones of increased signal power (constructive interference). This is also known as beam forming, the details of which will not be described herein. However, it will be evident that, in order to allow for beam forming and other control schemes, control signal <NUM> may include a plurality of different control signals for a plurality of different booster modules <NUM>. For example, control signal <NUM> may include different control signal portions, each including, for example, an ID of a designated booster module <NUM>, and splitter <NUM> and/or module controller <NUM> may use said ID to extract the control signal portion intended to be used by the respective booster modules <NUM>. The skilled person knows many different schemes for implementing such selective addressing of different control units with a control signal, such that no further details will be provided herein.

As shown in <FIG>, the centralized configuration of the embodiments disclosed herein allows for integration of at least RFID reader <NUM> and system controller <NUM> into a core unit <NUM> connected to at least one booster module <NUM>. For example, the integrated components may be provided in an appropriate housing, such that a detailed configuration of core unit <NUM> is not visible from the outside. In the exemplary embodiment shown in <FIG>, core unit <NUM> also includes power controller <NUM> and mixer <NUM>. In some embodiments, core unit <NUM> may also include one or more booster modules <NUM>, with one or more additional booster modules being external to core unit <NUM>.

To be able to configure the various aspects of the control performed by system controller <NUM>, a data processing device <NUM>, for example, a desktop computer, a tablet, or a mobile phone may be provided, and may be in communication with system controller <NUM>. Data processing device <NUM> is configured to specify control parameters for operating RFID reader <NUM> and at least one booster module <NUM>, i.e. configure/control the same to operate in a desired manner, as well as any other configurable aspect of the exemplarily described system <NUM>. Any appropriate control algorithm can be implemented by data processing device <NUM>. It will be appreciated that a user interface may be provided to allow easy administration of system <NUM> by an operator. In this respect, data processing device <NUM> may be connected to system controller <NUM> and, optionally, power controller <NUM> in a known manner, using a wired or wireless connection <NUM>.

As described above, with the exemplary systems described herein, a cost-effective and highly customizable extension of the capabilities of an RFID reader system becomes possible, by providing one or more booster modules that receive an RFID signal from the RFID reader, extract a reduced power portion of said signal, and amplify the same to transmit the amplified signal towards RFID tags to be read. In this manner, for example, an existing RFID reader may be upgraded by providing one or more booster modules as disclosed herein. Here, it will be evident that the total number of antennas, as well as the total power output by the system can be increased considerably. This results in increased read range, higher detection accuracy, and the like.

An exemplary implementation of the system described herein is shown in <FIG>. In the exemplary implementation, the system is applied to a portal <NUM> tracking entry and/or exit of persons carrying RFID tags <NUM>. For example, as shown in <FIG>, core unit <NUM> including RFID reader <NUM> and the other components described above may be attached to a side of portal <NUM>. In the example shown in <FIG>, core unit <NUM> includes four outputs, each output being associated with a corresponding output of RFID reader <NUM>.

To each output of core unit <NUM>, a single cable connection is connected, and each cable connection connects to one of booster modules <NUM> having the above-described exemplary configuration. In the example shown in <FIG>, each booster module <NUM> is configured to extract a reduced power portion of the RFID signal transmitted via the corresponding cable connection, and output the remaining power portion of the RFID signal to a reader antenna <NUM> (for example, a reader antenna <NUM> which was previously directly connected to RFID reader <NUM>). In this manner, it will be appreciated that the total number of antennas can be increased by the number of booster antennas <NUM> provided in the respective booster modules <NUM>. Appropriate control algorithms may be stored in a memory of controller <NUM>, and/or modified using data processing device <NUM> (see <FIG>), which may result in highly accurate reading of RFID tags <NUM>, for example, by successively activating the respective booster modules and associated reader antennas <NUM>, or simultaneously activating the same to create increased power zones for reading tags <NUM> in any appropriate manner. The details of such a control using the plurality of booster antennas <NUM> and reader antennas <NUM> will be immediately obvious to the skilled person from the above description, such that no further details will be described herein.

As initially mentioned, the system <NUM> described herein can also be used for other applications, such as inventory management, in particular, in cases where a large number of articles are present in a given space, and also for an accurate reading of RFID tags in difficult environments such as in environments in which the structure surrounding RFID tags <NUM> partially shields the same from electromagnetic radiation and/or the tags are in close proximity to each other.

It will be appreciated that the foregoing description provides examples of the disclosed systems and methods. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the general disclosure.

Recitation of ranges of values herein are merely intended to serve as a shorthand method for referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All method steps described herein can be performed in any suitable order, unless otherwise indicated or clearly contradicted by the context.

Claim 1:
A system (<NUM>) for reading RFID tags (<NUM>), comprising:
- an RFID reader (<NUM>) configured to output at least one RFID signal (<NUM>);
- at least one booster module (<NUM>) configured to receive the at least one RFID signal (<NUM>); and
- a system controller (<NUM>) configured to output a control signal (<NUM>) for the at least one booster module (<NUM>),
characterized in that
the at least one booster module (<NUM>) includes:
a module controller (<NUM>) configured to receive the control signal (<NUM>);
a power amplifier (<NUM>) configured to amplify at least a reduced power portion of the received RFID signal; and
at least one booster antenna (<NUM>) configured to emit the amplified RFID signal (<NUM>).