Patent ID: 12229619

Further aspects and features of the example embodiments described herein will appear from the following description taken together with the accompanying drawings.

DESCRIPTION OF VARIOUS EMBODIMENTS

It will be appreciated that, for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements or steps. In addition, numerous specific details are set forth in order to provide a thorough understanding of the exemplary embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein.

Furthermore, this description is not to be considered as limiting the scope of the embodiments described herein in any way but rather as merely describing the implementation of the various embodiments described herein.

In the description and drawings herein, reference may be made to a Cartesian co-ordinate system in which the vertical direction, or z-axis, extends in an up and down orientation from bottom to top. The x-axis extends in a first horizontal or width dimension perpendicular to the z-axis, and the y-axis extends cross-wise horizontally relative to the x-axis in a second horizontal or length dimension.

The terms “an embodiment,” “embodiment,” “embodiments,” “the embodiment,” “the embodiments,” “one or more embodiments,” “some embodiments,” and “one embodiment” mean “one or more (but not all) embodiments of the present invention(s),” unless expressly specified otherwise.

The terms “including,” “comprising” and variations thereof mean “including but not limited to,” unless expressly specified otherwise. A listing of items does not imply that any or all of the items are mutually exclusive, unless expressly specified otherwise.

The terms “a,” “an” and “the” mean “one or more,” unless expressly specified otherwise.

As used herein and in the claims, two or more parts are said to be “coupled”, “connected”, “attached”, or “fastened” where the parts are joined or operate together either directly or indirectly (i.e., through one or more intermediate parts), so long as a link occurs. As used herein and in the claims, two or more parts are said to be “directly coupled”, “directly connected”, “directly attached”, or “directly fastened” where the parts are connected in physical contact with each other. As used herein, two or more parts are said to be “rigidly coupled”, “rigidly connected”, “rigidly attached”, or “rigidly fastened” where the parts are coupled so as to move as one while maintaining a constant orientation relative to each other. None of the terms “coupled”, “connected”, “attached”, and “fastened” distinguish the manner in which two or more parts are joined together.

Embodiments herein provide a system and method of backscattered communication that is complaint with existing communications protocols, such as Wi-Fi 802.11g/n, Bluetooth®, and ZigBee. To this end, it will be noted that, while for simplicity and ease of description, embodiments herein reference communication via 802.11b compliant Wi-Fi frames, the described embodiments are not so limited such that the disclosed backscatter communication systems may operate with other similar communication standards.

Reference is made toFIG.1A, which is a simplified view of a backscatter communication system100aaccording to some embodiments.

As shown, the system100agenerally includes a transmitting unit102, a receiving unit104and a backscattering tag120. It will be understood that, in some embodiments, one or more of the transmitting and receiving units may in-fact comprise a device with combined transmitting and receiving functionalities.

As shown, the transmitter102is configured for transmitting 802.11b compliant Wi-Fi frames85at a pre-defined frequency. To this end, the transmitter102may also be referred to herein as an “excitation device”, and the transmitted signal85may also be referred to herein as an “excitation signal”. Transmitter102can comprise, for example, a mobile phone with a standard Wi-Fi radio (as shownFIG.1B). In other cases, transmitter102may be any other device configured to communicate via a Wi-Fi radio. In turn, receiver104is tuned to a pre-defined frequency (i.e., that may or may not be the same as that of the transmitter102) to receive the Wi-Fi frames85. In some cases, the receiver104can comprise, for example, a Wi-Fi access point, or any other suitable reception device.

As further shown, backscattering tag120operates to intercept the Wi-Fi frames85being transmitted to the receiver104. In particular, tag120is configured to manipulate the intercepted frames so to encode its own data information onto the Wi-Fi frames. Tag120may backscatter a signal95comprising frames having the tag's own data modifying the original data payload, i.e., the data payload transmitted by the transmitter102.

In more detail, tag120receives one or more frames in signal85containing the payload transmitted by the transmitter104. Tag120is then operable to manipulate the payload data to encode its own data. This process, of encoding the tag's own data over pre-existing data in signal85, is also known as “dirty paper encoding”.

Tag120may apply various different methods to manipulate the incident packet to generate the backscattered signal. For example, as described in U.S. Pat. No. 10,338,205 to Zhang et al, filed Aug. 14, 2017 and issued Jul. 2, 2019; and United States Publication No. 2019/0274144 to Zhang et al, filed Apr. 25, 2019, both of which are hereby incorporated in their entirety by reference, a code word translation scheme can be used. The codeword translation may involve, for example, XOR'ing the data bits in the original transmitted payload (i.e., signal85), with the tag's data, to generate the backscattered signal. In practice, codeword translation is performed by modifying, for example, one of the amplitude, phase or frequency of the incident excitation signal85.

To this end, backscattering tag120can include various passive circuitry components that operate on the received signal85in order to encode (i.e., manipulate) the signal85with the tag's own data. Various architectures and configurations for the passive circuitry for backscattering tags are known in the art.

The tag's own data, which is encoded by the tag120, can vary based on the application of system100a. For instance, in at least one example application, the tag data can comprise sensor data generated by a sensor system125coupled to the tag120. In this manner, and as stated in the background, backscattering tag120can facilitate implementation of ultra low-power sensor networks.

With continued reference toFIG.1A, in the system100a, the backscattered signal95is in the same frequency channel as the original excitation signal85. In turn, the receiver104receives both the original signal85, as well as the backscattered signal95, on a single frequency channel. Receiver104is then configured to process the data in the backscattered signal95such as to decode and isolate (i.e., disentangle) the tag's own data from the original transmitted data. In other cases, the decoding is performed by an external device connected to the receiver104(i.e., a decoding block150).

Here as well, various example methods for decoding and recovering the tag's own data will occur to the skilled artisan. For example, as described in U.S. Pat. No. 10,338,205 to Zhang et al and United States Publication No. 2019/0274144 to Zhang et al—the decoding may involve reversing the XOR operation performed by the tag120, and using an XOR decoder. The XOR decoder XOR's the bits in the data payload of the backscattered signal95with the bits in the data payload of the original signal85to recover the data bits associated with the tag's data.

In view of the foregoing, it has been appreciated that there are a number of significant drawback to the system100a. For example, the ability of the receiver104to decode the backscattered signal is often degraded by the interference generated by receiving signals85,95in the same frequency channel. At least for this reason, the receiver104may be unable to distinguish between the original transmitted signal85and the backscattered signal95. In turn, the receiver104is unable to effectively recover the tag's data by, for example, XOR'ing the data bits in the original signal85with the backscattered signal95.

Reference is now made toFIG.1B, which is a simplified view of a backscattering communication system100b, in accordance with some other embodiments

To at least partially mitigate the above-noted challenges inherent in system100a, system100bincludes two receivers104aand104b. Each receiver104a,104bis tuned to listen (i.e., receive) frames on a separate frequency channel.

In this embodiment, transmitter102transmits frames85on a first frequency channel. Receiver104ais, in turn, tuned to the first frequency channel to receive signal85. In contrast, however, to system100a—in addition to encoding the backscatter data—tag120is also further configured to frequency shift the backscattered signal95onto a different frequency. In this manner, tag120generates a frequency-shifted backscattered signal95which is compatible with the 802.11b standard. Second receiver104bis then tuned to the second frequency channel to receive backscattered signal95.

Decoding block150receives the original frames85from the first receiver104a, as well as the backscattered frames95from the second receiver104b, and proceeds to recover the tag's data in a manner analogous to that described in system100a. For instance, the decoding block150can comprise an XOR block that performs an XOR operation on the payload included in the two frames (i.e., frames in signals85and95) to recover the tag's data.

Various embodiments for implementing the system100bare also described in detail in U.S. Pat. No. 10,338,205 to Zhang et al and United States Publication No. 2019/0274144 to Zhang et al.

In view of the above, the system100bis believed to mitigate at least some of the drawbacks associated with the system100a. Namely, by frequency-shifting the backscattered signal95to an adjacent frequency channel, there is less interference between the backscattered signal95and the original signal85.

Still yet, the inventors have appreciated that system100bstill suffers from a number of important drawbacks. For example, system100brelies on a minimum of two receivers104a,104bfor effective functioning. System100bcannot otherwise function using a single receiver, tuned to a single frequency. This, in turn, adds a layer of hardware cost to implementing system110b.

In view of the foregoing, embodiments herein attempt to mitigate drawbacks of each the systems100aand100b, and provide for a backscatter communication system which enables use of a backscattering tag with only a single receiver.

In more detail, and as provided in greater detail herein, the disclosed embodiments allow for the transmitting device102to transmit—at pre-defined time or frequency interval—frames having pre-defined templates of payload data. That is, the payload data template is pre-defined in that it is known, apriori, to the receiver104(i.e., it is pre-defined from the receiver's perspective). In this manner, the receiver104(or the decoding device) is not required to rely on the data in the originally transmitted signal85in order to decode the backscattered signal95.

Reference is now made toFIG.2A, which illustrates an example embodiment of a backscatter communication system200a, in accordance with embodiments provided herein.

As shown, the backscatter system200ais generally analogous to the backscatter system100a, in that system200acomprises the transmitting device102, a single receiver104, and one or more backscattering tags120. Further, analogous to system100a—but in contrast to system100b—the backscattered signal95in system200amay be transmitted on the same, or a different, frequency channel as the original signal85.

To remove the need for two receivers as in100b, the system200arelies on transmitter102transmitting frames85carrying pre-defined payload data templates. These payload are known in advance to the receiver104. For instance, in the exemplified embodiment, the transmitter102may transmit a packet having an all “0” payload (i.e., “000000”).

Similar to system100a, backscattering tag120may receive the frames in signal85, and may encode its own data onto the packet payload. Tag120then backscatters the combined resulting packet for reception by receiver104. In at least some embodiments, tag120may also frequency-shift the backscattered signal95using passive circuitry components and methodologies as described in U.S. Pat. No. 10,338,205 to Zhang et al and United States Publication No. 2019/0274144 to Zhang et al. This can be done to avoid interference between the backscattered signal95and the original signal85, as previously explained.

At the receiver side, receiver104recovers the tag's data based on the apriori knowledge of the pre-defined template payload. For example, receiver104may

XOR the backscattered data payload with the known pre-defined template data payload, to recover the tag's data. In cases where the tag120frequency-shifts the backscattered signal95, the receiver104may also tune into the frequency of signal95, rather than original signal85.

In this manner, system200acan be distinguished from system100a, at least in that receiver104relies on its apriori knowledge of the payload in signal85to recover the tag's data. That is, the receiver's knowledge of the payload is not based, or contingent, on receiving signal85. Accordingly, receiving signal85is not essential to enable the receiver104to decode the tag's data. For this reason, in cases were the tag120frequency shifts the backscattered signal95, the receiver104can simply tune into the frequency shifted channel, and simply tune out of the frequency channel associated with original signal85. In this manner, system200acan operate using only a single receiver104, tuned to a single frequency channel at a given time.

As stated previously, in order to effect the system200b, the receiver104requires advanced knowledge of the data payload transmitted by transmitter102. Various methods are contemplated to inform the receiver104, of the pre-defined payload template, in advance.

For instance, in at least one example embodiment, transmitter102may be configured to always transmit the same template payload. Receiver104, in turn, may then be externally configured to store this pre-defined template, i.e., in a memory of the receiver104.

In another example embodiment, an initiation sequence between the transmitter102and the receiver104can enable the transmitter102to communicate the pre-defined template to the receiver104. For instance, as illustrated in the system200bofFIG.2B, a backbone network path202is provided. Backbone path202can comprise, for example, one or more switches204aand/or routers204bconnecting the transmitter102to the receiver104. As such, backbone path202can be used for an initiation sequence, in which the transmitter102communicates (directly or in-directly) the content of the packet payload to the receiver104in advance. An advantage of this system configuration is that the template payload may be dynamically varied by the transmitter102, insofar as the transmitter102is able to communicate the new pre-defined template payload in advance to the receiver104, via the backbone path202.

In still another example embodiment, the transmitter102can generate a frame that contains, in the frame header, a code indication reference of the pre-defined payload. That is, the header of the frame carrying the original data payload template can contain some code referring to the known template being used. In turn, receiver104can receive the frame in the backscattered signal95, and can extract the unmodified header to determine the nature of the pre-defined template.

Referring now toFIGS.2C and2D, which illustrate other example embodiments of a backscatter communication system200cand200d, respectively.

Backscatter systems200cand200doperate using the same principles as the backscattering system200b, with the exception that multiple receivers104a-104eare provided. For example, the multiple receivers104can include a wireless LAN Access Point (WLAN AP)104a, a server104b, a smartphone104c, a host104dand a mobile computer104e. In this embodiment, the backscattered signal95may be received by one or more of the plurality of receivers104. Accordingly, each of the receivers104may have advanced knowledge of the pre-defined template transmitted by transmitter102.

To this end, in the system200c, the pre-defined template comprises an all-zero payload (i.e., “000000”), while in the system200dthe pre-defined template comprises an all-one payload (i.e., “11111”). In each example, an example phase shift key (PSK) modulation scheme is used by the tag102to encode the tag's data onto the original payload data.

Reference is now made toFIG.3, which shows a process flow for an example embodiment of a method300for backscatter communication, in accordance with some embodiments.

As shown, at302, transmitter102can transmit a frame having a pre-defined template for its data payload. At304, the backscattering tag120can receive the packet, and can generate a backscattered frame by encoding the tag's own data over the payload data in the received frame. At306, the backscattering tag120can transmit the backscattered frame. At308, the receiver104can receive and decode the data in the backscattered frame to recover the tag's own data. As explained previously, this can be performed based on the receiver's advanced knowledge of the payload of the original packet generated by transmitter102.

While the above description provides examples of the embodiments, it will be appreciated that some features and/or functions of the described embodiments are susceptible to modification without departing from the spirit and principles of operation of the described embodiments. Accordingly, what has been described above has been intended to be illustrative of the invention and non-limiting and it will be understood by persons skilled in the art that other variants and modifications may be made without departing from the scope of the invention as defined in the claims appended hereto. The scope of the claims should not be limited by the preferred embodiments and examples, but should be given the broadest interpretation consistent with the description as a whole.