High performance synchronization apparatus and method based on cellular network backscatter

Abstract

The application discloses a high-performance synchronization device and method based on cellular network backscattering, which comprises an envelope detector, a voltage comparator, a preprocessing module and a periodic template matching module. The envelope detector is electrically connected with the voltage comparator and can extract the envelope of the cellular excitation signal from the cellular base station and send it to the voltage comparator. The voltage comparator is communicatively connected with the preprocessing module and can quantitatively process the envelope of the cellular excitation signal obtained by the envelope detector to obtain a quantized envelope signal. The preprocessing module is communicatively connected with the periodic template matching module, can store a template, perform down-sampling processing on the quantized envelope signal output by the voltage comparator to obtain a down-sampled quantized signal, and send the down-sampled quantized signal to the periodic template matching module. The periodic template matching module periodically matches the down-sampled quantized signal sent by the preprocessing module with the template, and if a matching rule is met, it is confirmed that the synchronization is successful. The device can realize low-power and accurate synchronization of cellular network backscattering.

Description

Technical Field

[0001] This invention relates to the field of backscatter communication, and more particularly to a high-performance synchronization device and method based on backscattering from a cellular network. Background Technology

[0002] Backscatter communication has attracted significant attention due to its promise of providing ubiquitous connectivity for Internet of Things (IoT) devices. Unlike active radio, backscatter radio has limited resources, leading to inefficient communication. A backscatter system consists of a transmitter, a backscattering device, and a receiver. In terms of energy efficiency, it consumes less energy to correctly transmit the same amount of data, which requires the tag, acting as the backscattering device, to achieve low power consumption and precise synchronization.

[0003] For backscatter transmission, the tag must first synchronize with the ambient carrier. Active radios such as LTE, WiFi, and RFID use cross-correlation for precise synchronization, but this consumes significant power, making it unsuitable for ultra-low-power tags. While advanced LTE backscatter systems have achieved lower power consumption through passive synchronization circuitry and simple rising-edge detection, their synchronization accuracy is lower, which degrades modulation quality. Therefore, achieving precise tag synchronization with the carrier while maintaining low power consumption is a challenge. Existing backscatter work has proposed downsampling cross-correlation for precise synchronization while maintaining high energy efficiency. However, for continuous cellular signals, this synchronization cannot achieve both low power consumption and high accuracy.

[0004] Synchronization in existing backscatter work includes two types: rising edge detection and template matching. Previous works were primarily designed for burst traffic, and therefore they are mainly based on signal strength. These methods detect the target signal based on the difference in signal strength between signals. However, existing signal strength-based synchronization methods have at least the following drawbacks for cellular signals:

[0005] (1) Energy-based rising edge detection method: Although this method can be used to detect the arrival of data packets by burst signals, since cellular signals are continuous, this method will keep the tag in an excited state and will not be able to transmit data.

[0006] (2) Primary Synchronization Signal (PSS) Rising Edge Detection Method: Due to the complex frame structure of cellular signals, this PSS rising edge detection method can be erroneously triggered by interference signals such as PDSCH (Physical Downlink Shared Channel) data, and cannot be accurately synchronized with cellular signals.

[0007] In summary, any synchronization method based on signal strength has low accuracy. Inaccurate synchronization leads to modulation position shift and a high demodulation bit error rate (BER), especially in scenarios with low signal-to-noise ratio (SNR) or high data rate.

[0008] Furthermore, the inventors' simulation results quantitatively demonstrate the impact of synchronization error on BER. Experiments show that BER increases with synchronization error at any SNR. Therefore, inaccurate synchronization increases demodulation error and reduces transmission efficiency. The conclusion is that accurate synchronization is a prerequisite for ensuring transmission efficiency.

[0009] In view of this, the present invention is hereby proposed. Summary of the Invention

[0010] The purpose of this invention is to provide a high-performance synchronization device and method based on cellular network backscattering, which can use continuous environmental cellular signals as carriers and achieve reliable transmission by accurately synchronizing with the carrier, thereby solving the above-mentioned technical problems existing in the prior art.

[0011] The objective of this invention is achieved through the following technical solution:

[0012] A high-performance synchronization device based on cellular network backscattering includes:

[0013] Envelope detector, voltage comparator, preprocessing module, and periodic template matching module; among which,

[0014] The envelope detector is electrically connected to the voltage comparator and can extract the envelope of the cellular excitation signal from the cellular base station and send it to the voltage comparator.

[0015] The voltage comparator is communicatively connected to the preprocessing module and can quantize the envelope of the cellular excitation signal acquired by the envelope detector to obtain a quantized envelope signal.

[0016] The preprocessing module is communicatively connected to the periodic template matching module. It can store templates and perform downsampling processing on the quantized envelope signal output by the voltage comparator to obtain a downsampled quantized signal, which is then sent to the periodic template matching module.

[0017] The periodic template matching module performs periodic template matching between the downsampled quantized signal sent by the preprocessing module and the template. If the matching rules are met, the synchronization is confirmed to be successful.

[0018] A high-performance synchronization method based on backscattering from a cellular network, employing the synchronization device described in this invention, includes:

[0019] The envelope of the cellular excitation signal from the cellular base station is extracted by the envelope detector of the synchronization device and sent to the voltage comparator;

[0020] The voltage comparator of the synchronization device quantizes the envelope of the cellular excitation signal acquired by the envelope detector to obtain a quantized envelope signal.

[0021] The preprocessing module of the synchronization device stores the template and downsamples the quantized envelope signal output by the voltage comparator to obtain the downsampled quantized signal, which is then sent to the periodic template matching module.

[0022] The periodic template matching module of the synchronization device periodically matches the downsampled quantized signal sent by the preprocessing module with the template. If the matching rules are met, the synchronization is confirmed to be successful.

[0023] Compared with the prior art, the high-performance synchronization device and method based on cellular network backscattering provided by the present invention have the following advantages:

[0024] By downsampling and quantizing the input signal, and using the downsampling and quantized synchronization signal as a template for template matching synchronization, and by utilizing the periodicity of cellular signals to design periodic template matching, synchronization accuracy is improved by trading time for efficiency, while ensuring low power consumption. This avoids the problem of inaccurate synchronization due to insufficient sampling accuracy. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram illustrating the configuration of a high-performance synchronization device based on cellular network backscattering, as provided in an embodiment of the present invention.

[0027] Figure 2 This is a schematic diagram of the configuration of a high-performance synchronization system based on cellular network backscattering provided in an embodiment of the present invention.

[0028] Figure 3 This is a schematic diagram of the backscattering synchronization process of a high-performance synchronization method based on cellular network backscattering provided in an embodiment of the present invention. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the specific content of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments, which do not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0030] First, the following explanations are provided for the terms that may be used in this article:

[0031] The term "and / or" means that either or both can be achieved simultaneously. For example, X and / or Y means that it includes both "X" or "Y" as well as the three cases of "X and Y".

[0032] The terms “including,” “comprising,” “containing,” “having,” or other similar semantic descriptions should be interpreted as non-exclusive inclusion. For example, “including a technical feature element (such as raw material, component, ingredient, carrier, dosage form, material, size, part, component, mechanism, device, step, process, method, reaction conditions, processing conditions, parameter, algorithm, signal, data, product or article of manufacture, etc.)” should be interpreted as including not only the expressly listed technical feature element, but also other technical feature elements that are not expressly listed and are well-known in the art.

[0033] The term "composed of" excludes any technical features not expressly listed. When used in a claim, it closes the claim to exclude all technical features other than those expressly listed, except for associated conventional impurities. If the term appears only in a clause of a claim, it limits the claim to the elements expressly listed in that clause; elements recited in other clauses are not excluded from the overall claim.

[0034] Unless otherwise explicitly specified or limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this document according to the specific circumstances.

[0035] The terms “center,” “longitudinal,” “lateral,” “length,” “width,” “thickness,” “upper,” “lower,” “front,” “back,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,” “clockwise,” and “counterclockwise” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience and simplification of description and do not imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this document.

[0036] The high-performance synchronization device and method based on cellular network backscattering provided by this invention will be described in detail below. Contents not described in detail in the embodiments of this invention are prior art known to those skilled in the art. Where specific conditions are not specified in the embodiments of this invention, they shall be performed according to conventional conditions in the art or conditions recommended by the manufacturer. Where the manufacturers of reagents or instruments used in the embodiments of this invention are not specified, they are all conventional products that can be purchased commercially.

[0037] like Figure 1 , Figure 2 As shown, an embodiment of the present invention provides a high-performance synchronization device based on cellular network backscattering, comprising:

[0038] Envelope detector, voltage comparator, preprocessing module, and periodic template matching module; among which,

[0039] The envelope detector is electrically connected to the voltage comparator and can extract the envelope of the cellular excitation signal from the cellular base station and send it to the voltage comparator.

[0040] The voltage comparator is communicatively connected to the preprocessing module and can quantize the envelope of the cellular excitation signal acquired by the envelope detector to obtain a quantized envelope signal.

[0041] The preprocessing module is communicatively connected to the periodic template matching module. It can store templates and perform downsampling processing on the quantized envelope signal output by the voltage comparator to obtain a downsampled quantized signal, which is then sent to the periodic template matching module.

[0042] The periodic template matching module performs periodic template matching between the downsampled quantized signal sent by the preprocessing module and the template. If the matching rules are met, the synchronization is confirmed to be successful.

[0043] Preferably, in the above-mentioned synchronization device, the downsampling frequency of the preprocessing module is 1MHz.

[0044] Preferably, in the above-mentioned synchronization device, the periodic template matching module determines the starting matching point based on the correlation coefficient obtained by the periodic template matching module in the following manner:

[0045] When the correlation coefficient exceeds the preset threshold, the match is considered successful and recorded as bit 1; otherwise, it is recorded as bit 0. The first point where the correlation coefficient exceeds the preset threshold is taken as the starting position and used as the starting matching point.

[0046] Preferably, in the above-mentioned synchronization device, the matching rules in the periodic template matching module include:

[0047] Exact match: Use the results of consecutive matches as the synchronization position, and the number of consecutive matches is no less than 3;

[0048] Selective matching: Select b matching results from the total number of times a as the synchronization position, where b < a, and a and b are both integers greater than 0.

[0049] Preferably, in the above-mentioned synchronization device, the preset duration of template matching detection in the periodic template matching module is 5 milliseconds.

[0050] See Figure 3 The present invention further provides a high-performance synchronization method based on cellular network backscattering, employing the above-mentioned synchronization device, comprising:

[0051] The envelope of the cellular excitation signal from the cellular base station is extracted by the envelope detector of the synchronization device and sent to the voltage comparator;

[0052] The voltage comparator of the synchronization device quantizes the envelope of the cellular excitation signal acquired by the envelope detector to obtain a quantized envelope signal.

[0053] The preprocessing module of the synchronization device stores the template and downsamples the quantized envelope signal output by the voltage comparator to obtain the downsampled quantized signal, which is then sent to the periodic template matching module.

[0054] The periodic template matching module of the synchronization device periodically matches the downsampled quantized signal sent by the preprocessing module with the template. If the matching rules are met, the synchronization is confirmed to be successful.

[0055] Preferably, in the above synchronization method, the downsampling frequency of the preprocessing module is 1MHz.

[0056] Preferably, in the above synchronization method, the periodic template matching module determines the starting matching point based on the correlation coefficient obtained by the periodic template matching module in the following manner:

[0057] When the correlation coefficient exceeds the preset threshold, it is considered a successful match, recorded as bit 1, otherwise recorded as bit 0. Taking the first point where the correlation coefficient exceeds the preset threshold as the starting position, it is used as the starting matching point.

[0058] Preferably, in the above synchronization method, in the periodic template matching module, the matching rules include:

[0059] Exact matching: Taking the result of continuous matching as the synchronization position, and the number of continuous matches is not less than 3;

[0060] Selective matching: Selecting the results of b matches out of a total of a matches as the synchronization position, where b < a, and both a and b are positive integers greater than 0.

[0061] Preferably, in the above synchronization method, in the periodic template matching module, the preset duration for template matching detection is 5 milliseconds.

[0062] In summary, in the device and method of the embodiments of the present invention, by downsampling and quantifying the input signal, using the downsampled and quantified synchronization signal as a template for template matching synchronization, and designing a periodic template matching using the periodicity of the cellular signal, trading time for synchronization accuracy while ensuring low power consumption, avoiding the problem of inaccurate synchronization due to insufficient sampling accuracy.The performance of different synchronization implementations is evaluated as shown in Table 4. Implementing low-power synchronization using AGLN250 with a digital core power of 6.13 mW (referring to the tag implemented using AGLN250 FPGA) is 5.6 times and 18.9 times lower than that of active LTE with a long template and simple ZYNQ respectively. Additionally, the synchronization power simulation results of ZYNQ are as follows: the FPGA power consumption is 116 mW, since it uses a mixed-mode clock manager (MMCM), the oscillator power consumption is 3 mW, so the comparator power consumption is 0.18 mW, and its total power is 119.18 mW. The measured synchronization power of AGLN250 includes: digital core power of 6.13 mW, oscillator power of 0.42 mW, comparator power of 0.18 mW, and the total power is 6.73 mW, which is 17.7 times lower than the total power of ZYNQ. Our synchronization is inherently low-power because we use downsampling and a shortened template length on the low-power AGLN250. Note that AGLN250 is made using the old 130-nanometer CMOS process, so the power consumption can be further reduced. The total power for our synchronization using IC simulation is 234.8 μW.

[0063] Table 4 shows the synchronization power of different synchronization implementation methods

[0064]

[0065] To more clearly demonstrate the technical solution and its effects provided by the present invention, the following detailed description of the high-performance synchronization device and method based on cellular network backscattering provided by the present invention is given with reference to specific embodiments.

[0066] Example 1

[0067] This invention provides a high-performance synchronization device based on cellular network backscattering. Figure 2 A schematic diagram of the synchronization device is shown. The basic idea of ​​this invention is to achieve synchronization through template matching. Active LTE uses IQ samples as input, associates the incoming signal with a template, and uses the point with the highest correlation coefficient as the synchronization position. However, low-power tags cannot acquire IQ data. To ensure low power consumption, tags typically use envelope detectors to acquire the envelope containing the carrier amplitude. Therefore, the characteristics of the carrier envelope can be used to select the template. The template for active LTE is the synchronization signal PSS and SSS. Similarly, the envelopes of PSS and SSS can be used as the matching template for the tag of this invention.

[0068] 1) Low-Power Periodic Template Matching: To obtain sufficiently good data quality, acquiring and sampling a high-quality envelope is crucial. If computational resources were not an issue, the required synchronization accuracy could be achieved. However, ultra-low-power tags have limited computational and storage resources, making high-frequency and high-sampling-depth sampling of the signal impossible. Specifically, cross-correlation calculations involve multiplication. If cross-correlation is used directly for synchronization with a template size of 1000, the AGLN250 would require 999 adders and 1000 multipliers for correlation. Furthermore, since the sampled data length is 10 bits, each 10×10 adder uses 21 D flip-flops, and each multiplier uses 328 D flip-flops. The result is a total of 348,979 D-Flip-Flops, far exceeding the computational resources of the AGLN250, which contains only 6,144 D-Flip-Flops. Considering computational and storage limitations, the tag quantizes the received envelope. Quantization reduces the sampling depth to 1 and converts multiplication into addition. However, quantization alone is insufficient. The AGLN250 requires 29,554 D flip-flops, which still exceeds computational resources. Therefore, the synchronization device of this invention downsamples the signal, using the quantized and downsampled synchronization signal as a template to minimize its size. Matching the quantized signal to the template ensures low power consumption for the tag. In this invention, downsampling to 1MHz reduces the template size from 1000 to 100. Therefore, 1,996 D flip-flops are sufficient for synchronization.

[0069] Experimental observations revealed poor synchronization performance due to insufficient sampling accuracy. To improve synchronization accuracy without increasing power consumption, this invention employs periodic template matching. Based on the synchronization signal repeating every 5ms, template matching is performed periodically with a 5ms pre-matching duration to achieve a discontinuous extension of the template length. The template length remains unchanged, preserving the duration of one synchronization signal (PSS and SSS). Therefore, synchronization maintains low power consumption as no further power consumption is generated. Although periodic template matching increases synchronization delay, it achieves more accurate synchronization while ensuring low power consumption. This invention evaluated synchronization performance at different sampling rates. It was confirmed that at a sampling rate of 1MHz, the 80th percentile of the synchronization error is 23μs, the power consumption is 6.41mW, and the total resource consumption is 3250 D-Flip-Flops. Therefore, synchronization using 1MHz sampling meets the synchronization requirements.

[0070] 2) Matching Rules: Matching rules are crucial for improving synchronization accuracy. First, let's introduce the basic ideas of synchronization. For example... Figure 3 As shown, after downsampling and quantization, the synchronization device matches the quantized envelope with the pre-stored template. When the correlation coefficient exceeds a threshold, a match is considered to have occurred and recorded as bit 1; otherwise, it is recorded as bit 0. The first point where the correlation coefficient exceeds the threshold is taken as the starting position and used as the matching point. Template matching is performed every PSS cycle, and the quantized correlation coefficient is periodically updated as the matching result P. Next, two matching rules are discussed: Matching rule 1, exact matching, uses the results of consecutive matching as the synchronization position. For example, when a = 3, the synchronization position is the intersection of the three matching results P1∩P2∩P3, where Pi is the i-th matching result, i∈{1,2,3}; Matching rule 2, selective matching, takes b (b < a) matching results out of the total number of times a as the synchronization position. For example, when a = 3 and b = 2, the synchronization position is P1∩P2∪P1∩P3∪P2∩P3. By evaluating the synchronization effectiveness of the two matching rules, precise matching achieved a synchronization error of 23 μs at the 80th percentile, which is 11 times better than selective matching. The median synchronization delay (time to find the matching signal) for selective matching was 25 ms, 1.8 times lower than precise matching. Considering both synchronization error and delay, precise matching better meets the requirements.

[0071] Example 2

[0072] This embodiment provides a method for synchronization and data transmission in an LTE backscatter network using the synchronization device of Embodiment 1, including:

[0073] For LTE downlink traffic with arbitrary content, the tag equipped with the synchronization device of Example 1 first acquires a high-quality LTE envelope and periodically matches a pre-stored template with the incoming LTE envelope. When three synchronization signals PSS and SSS are detected consecutively, the tag successfully synchronizes with the LTE carrier. Next, the tag begins to use PSK to modulate the data on the symbol containing the reference signal in the LTE frame. To reduce the cumulative time drift between the LTE cell and the tag caused by SFO, the tag does not strictly determine the modulation start point of each half-frame according to the PSS period (5ms), but instead uses the drift obtained by least-squares fitting to calibrate and determine the start of each modulation. Once the modulation start is determined, the tag performs backscatter modulation until the next template matching to update the synchronization position. The modulation time required for SFO calibration is 1000 times longer than that without calibration, thereby increasing the carrier utilization to 1.

[0074] For backscatter demodulation, once a backscatter signal is received on the frequency-shifted channel, a single LTE receiver demodulates the tag data using a predefined and invariant reference signal and recovers the ambient data by eliminating the additional phase imposed on the reference signal by the tag.

[0075] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0076] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. The information disclosed in the background section is intended only to enhance the understanding of the overall background technology of the present invention and should not be construed as an admission or implication in any way that such information constitutes prior art known to those skilled in the art.

Claims

1. A high-performance synchronization device based on backscattering from a cellular network, characterized in that, include: Envelope detector, voltage comparator, preprocessing module, and periodic template matching module; among which, The envelope detector is electrically connected to the voltage comparator and can extract the envelope of the cellular excitation signal from the cellular base station and send it to the voltage comparator. The voltage comparator is communicatively connected to the preprocessing module and can quantize the envelope of the cellular excitation signal acquired by the envelope detector to obtain a quantized envelope signal. The preprocessing module is communicatively connected to the periodic template matching module. It can store templates and perform downsampling processing on the quantized envelope signal output by the voltage comparator to obtain a downsampled quantized signal, which is then sent to the periodic template matching module. The periodic template matching module performs periodic template matching between the downsampled quantized signal sent by the preprocessing module and the template. If the matching rules are met, the synchronization is confirmed to be successful. The periodic template matching module determines the starting matching point based on the correlation coefficient obtained by the periodic template matching module in the following manner: When the correlation coefficient exceeds the preset threshold, the match is considered successful and recorded as bit 1; otherwise, it is recorded as bit 0. The first point where the correlation coefficient exceeds the preset threshold is taken as the starting position and used as the starting matching point. The matching rules in the periodic template matching module include: Exact match: Uses the results of consecutive matches as the synchronization position; Selective matching: Select b matching results from the total number of times a as the synchronization position, where b < a, and a and b are both integers greater than 0.

2. The high-performance synchronization device based on cellular network backscattering according to claim 1, characterized in that, The preprocessing module downsamples at a frequency of 1MHz.

3. The high-performance synchronization device based on cellular network backscattering according to claim 1, characterized in that, In exact match rules, the number of consecutive matches must be no less than 3.

4. The high-performance synchronization device based on cellular network backscattering according to claim 1 or 2, characterized in that, In the periodic template matching module, the preset duration for template matching detection is 5 milliseconds.

5. A high-performance synchronization method based on backscattering from a cellular network, characterized in that, The synchronization device according to any one of claims 1 to 4 comprises: The envelope of the cellular excitation signal from the cellular base station is extracted by the envelope detector of the synchronization device and sent to the voltage comparator; The voltage comparator of the synchronization device quantizes the envelope of the cellular excitation signal acquired by the envelope detector to obtain a quantized envelope signal. The preprocessing module of the synchronization device stores the template and downsamples the quantized envelope signal output by the voltage comparator to obtain the downsampled quantized signal, which is then sent to the periodic template matching module. The periodic template matching module of the synchronization device periodically matches the downsampled quantized signal sent by the preprocessing module with the template. If the matching rules are met, the synchronization is confirmed to be successful. The template matching module determines the starting matching point based on the correlation coefficient obtained by the template matching module in the following manner: When the correlation coefficient exceeds the preset threshold, the match is considered successful and recorded as bit 1; otherwise, it is recorded as bit 0. The first point where the correlation coefficient exceeds the preset threshold is taken as the starting position and used as the starting matching point. The matching rules in the periodic template matching module include: Exact match: Uses consecutive matches as synchronization positions, with a minimum of 3 consecutive matches; Selective matching: Select b matching results from the total number of times a as the synchronization position, where b < a, and a and b are both integers greater than 0.

6. The high-performance synchronization method based on cellular network backscattering according to claim 5, characterized in that, The preprocessing module downsamples at a frequency of 1MHz.

7. The high-performance synchronization method based on cellular network backscattering according to claim 5, characterized in that, In the periodic template matching module, the preset duration for template matching detection is 5 milliseconds.

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