High-precision synchronization method and system for backscatter communication against wake-up delay

Abstract

The present invention provides a high-precision synchronization method and system for backscatter communications that combats wake-up delays, including: Step S1: transmitting a control frame to synchronize with a tag, the control frame comprising a coarse synchronization sequence and a fine synchronization sequence; Step S2: the tag wake-up module performs coarse synchronization using the coarse synchronization sequence, waking up the tag synchronization module after synchronization is complete; Step S3: after waking up, the tag synchronization module performs synchronization using the fine synchronization sequence, aligning the tag with the data frame in the time domain. By carefully designing the fine synchronization sequence, the present invention enables the tag to combat wake-up delays and achieve high-precision synchronization. The tags of the present invention also feature ultra-low power consumption, and the additional synchronization module remains dormant most of the time, waking up and operating only when high-precision synchronization is required.

Description

Technical Field

[0001] The present invention relates to the field of communications, and in particular to a high-precision synchronization method and system for backscatter communications that combats wake-up delays. Background Art

[0002] Backscatter communication has been widely used in radio frequency identification (RFID) systems, with numerous large-scale commercial applications. Its operating principle is that a receiver transmits an RF excitation signal to activate a passive node. The electronic tag then uses backscatter communication to modulate its information onto the RF signal. The reader then receives the reflected signal from the passive tag and demodulates it, enabling information transmission. However, existing backscatter communication systems cannot simultaneously connect multiple tags.

[0003] Patent document CN109076014A (Application Number: CN201780027114.7) discloses a method for synchronizing a label database in a packet-switched communication network, comprising the following steps: establishing a communication path between a stateful path computation element (PCE) and a path computation client (PCC); modifying a label update message at the PCE to include a synchronization flag; and transmitting the label update message to the PCC. However, this invention does not utilize coarse and fine synchronization sequences for higher-precision synchronization.

[0004] Patent document CN102799839B (application number: CN201110133835.0) discloses a method for synchronous awakening communication of an active RFID system. After the system is powered on, the active RFID card reader operates in a receiving state, and the active RFID electronic tag sends information to the card reader. After receiving the information, the card reader sends a reply signal to the electronic tag. Both parties use this time as the starting point and begin to enter synchronization. A timed synchronous awakening method, a synchronous calibration process, and a synchronous frequency hopping process can also be added to the synchronous awakening process. The present invention uses the successful first communication between the RFID electronic tag and the RFID card reader as a time synchronization signal, and subsequent communications are awakened according to the established time, thereby achieving synchronous awakening of the two in a sleep state, which is more power-saving. However, this invention does not eliminate the different wake-up delays between tags. Summary of the Invention

[0005] In view of the defects in the prior art, the object of the present invention is to provide a high-precision synchronization method and system for backscatter communication that can combat wake-up delays.

[0006] According to the present invention, a high-precision synchronization method for backscatter communication against wake-up delay is provided, comprising:

[0007] Step S1: transmitting a control frame to synchronize with the tag, the control frame including a coarse synchronization sequence and a fine synchronization sequence;

[0008] Step S2: The tag wake-up module performs coarse synchronization using the coarse synchronization sequence, and wakes up the tag synchronization module after synchronization is completed;

[0009] Step S3: After waking up, the tag synchronization module uses the fine synchronization sequence to synchronize with the data frame in the time domain.

[0010] Preferably, in step S1:

[0011] Step S1.1: Generate a bit sequence for identifying the order according to a preset number of synchronization times N;

[0012] Step S1.2: performing an XOR or XOR operation on the generated sequence identifier sequence and the preset Barker code bit by bit to generate a synchronization sequence;

[0013] Step S1.3: splicing the generated synchronization sequence with the preset equal-length gap sequence to form a complete fine synchronization sequence;

[0014] Step S1.4: Add the generated fine synchronization sequence to the control frame. The transmitter in the reflection communication system transmits the control frame before transmitting the data frame to achieve synchronization with the tag.

[0015] Preferably, the step S1.1 includes: the number of high-precision synchronization times N is not limited, and the length of a single sequence identifier is

[0016] The step S1.2 includes: the preset Barker code does not limit the Barker code length;

[0017] The step S1.3 comprises: separating two adjacent sequence identifiers using the preset equal-length gap sequence so that they do not affect each other when calculating the correlation coefficient;

[0018] There are two designs for equal-length gap sequences: the first is all 0s or all 1s, suitable for synchronization modules whose decision threshold stability exceeds the preset standard; the second is alternating 0s and 1s, suitable for synchronization modules whose decision threshold dynamically adjusts with environmental signals.

[0019] The step S1.4 includes: the reflection communication system does not limit the number of tag nodes, and can be a single node or multiple nodes, wherein the number of nodes in the multi-node reflection communication system is determined by the hardware characteristics of the analog circuit of the hardware.

[0020] Preferably, in step S3:

[0021] Step S3.1: The tag's synchronization module is awakened after a delay and starts synchronization;

[0022] Step S3.2: The synchronization module uses the decision circuit to demodulate the fine synchronization sequence to achieve analog-to-digital conversion;

[0023] Step S3.3: The bit sequence obtained by analog-to-digital conversion is input to multiple Barker code correlators in the digital circuit. A single correlator uses the Barker code to perform an exclusive-OR or exclusive-OR operation on the input sequence. The obtained results are then bitwise summed and bitwise negated and then summed to obtain two correlation results, PC and NC, respectively.

[0024] Step S3.4: PC and NC are compared with the thresholds respectively to obtain two binary results P and N. When the sum of P and N is 0, it is determined that the transmitted bit is invalid. When the sum of P and N is 1, it is determined that the transmitted bit is equal to N or P. When all bits are determined to be valid, all bits are concatenated to obtain a single sequence identifier.

[0025] Step S3.5: After obtaining the sequence identifier, the tag and the control frame are aligned in the time domain, and the timer in the synchronization module starts timing, waiting for the control frame to be transmitted. When the data frame arrives, the tag starts modulation.

[0026] Preferably, the step S3.1 includes: the wake-up delay generating factors include the WuRx wake-up receiver and the energy acquisition circuit;

[0027] Step S3.3 includes: wherein the number of Barker code correlators depends on the number of bits of a single sequence identifier symbol. When the number of bits is X, the bit sequence input to the correlator has a total of X segments, each segment length equal to the Barker code length, and correlation results are calculated by the X Barker code correlators in sequence;

[0028] When the fine synchronization sequence is generated by using the exclusive OR or exclusive OR operation, the correlator adopts the exclusive OR or exclusive OR operation;

[0029] The step S3.4 includes: the threshold is a constant value, which is determined according to the length of the Barker code and actual conditions, and the maximum threshold of the Y-bit Barker code is Y.

[0030] According to the present invention, a high-precision synchronization system for backscatter communication that resists wake-up delay is provided, comprising:

[0031] Module M1: transmits control frames to synchronize with tags. The control frames contain coarse synchronization sequences and fine synchronization sequences.

[0032] Module M2: The tag wake-up module uses the coarse synchronization sequence to perform coarse synchronization, and wakes up the tag synchronization module after synchronization is completed;

[0033] Module M3: After waking up, the tag synchronization module uses the fine synchronization sequence to synchronize with the data frame in the time domain.

[0034] Preferably, in the module M1:

[0035] Module M1.1: Generates a bit sequence to identify the order according to the preset number of synchronizations N;

[0036] Module M1.2: Perform XOR or XOR operations on the generated sequence identifier sequence and the preset Barker code bit by bit to generate a synchronization sequence;

[0037] Module M1.3: Splice the generated synchronization sequence with the preset equal-length gap sequence to form a complete fine synchronization sequence;

[0038] Module M1.4: Add the generated fine synchronization sequence to the control frame. The transmitter in the reflection communication system synchronizes with the tag by transmitting the control frame before transmitting the data frame.

[0039] Preferably, the module M1.1 includes: the number of high-precision synchronization times N is not limited, and the length of a single sequence identifier is

[0040] The module M1.2 includes: the preset Barker code does not limit the Barker code length;

[0041] The module M1.3 includes: the preset equal-length gap sequence separates two adjacent order identifier symbols so that they do not affect each other when calculating the correlation coefficient;

[0042] There are two designs for equal-length gap sequences: the first is all 0s or all 1s, suitable for synchronization modules whose decision threshold stability exceeds the preset standard; the second is alternating 0s and 1s, suitable for synchronization modules whose decision threshold dynamically adjusts with environmental signals.

[0043] The module M1.4 includes: the reflection communication system does not limit the number of tag nodes, and can be a single node or multiple nodes, wherein the number of nodes in the multi-node reflection communication system is determined by the analog circuit hardware characteristics of the hardware.

[0044] Preferably, in the module M3:

[0045] Module M3.1: The tag's synchronization module is awakened after a delay and starts synchronization;

[0046] Module M3.2: The synchronization module uses the decision circuit to demodulate the fine synchronization sequence and realize analog-to-digital conversion;

[0047] Module M3.3: The bit sequence obtained by analog-to-digital conversion is input into multiple Barker code correlators in the digital circuit. A single correlator uses the Barker code to perform an exclusive-OR or exclusive-OR operation on the input sequence. The resulting results are then bitwise summed and bitwise negated and then summed to obtain two correlation results, PC and NC, respectively.

[0048] Module M3.4: Compare PC and NC with the thresholds respectively to obtain two binary results P and N. When the sum of P and N is 0, the transmitted bit is determined to be invalid. When the sum of P and N is 1, the transmitted bit is determined to be equal to N or P. When all bits are determined to be valid, all bits are concatenated to obtain a single sequence identifier.

[0049] Module M3.5: After obtaining the sequence identifier, the tag and the control frame are aligned in the time domain. The timer in the synchronization module starts timing, waiting for the control frame to be transmitted. When the data frame arrives, the tag starts modulation.

[0050] Preferably, the module M3.1 includes: the wake-up delay generating factors include WuRx wake-up receiver and energy acquisition circuit;

[0051] The module M3.3 includes: wherein the number of Barker code correlators depends on the number of bits of a single sequence identifier. When the number of bits is X, the bit sequence input to the correlator has a total of X segments, each segment length is equal to the Barker code length, and correlation results are calculated by the X Barker code correlators in sequence;

[0052] When the fine synchronization sequence is generated by using the exclusive OR or exclusive OR operation, the correlator adopts the exclusive OR or exclusive OR operation;

[0053] The module M3.4 includes: the threshold is a constant value, which is determined according to the length of the Barker code and actual conditions, and the maximum threshold of the Y-bit Barker code is Y.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] 1. The present invention carefully designs a fine synchronization sequence to enable the tag to resist wake-up delay and achieve high-precision synchronization;

[0056] 2. The tag of the present invention still has the characteristics of ultra-low power consumption. The additional synchronization module is in a dormant state most of the time and is awakened and put into working state only when high-precision synchronization is required.

[0057] 3. The fine synchronization sequence carefully designed by the present invention has good robustness and can effectively eliminate different wake-up delays between tags. It is suitable for reflection communication systems that require synchronous access of multiple tags. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0059] Figure 1 Schematic diagram of the multi-tag synchronous access process in a multi-tag reflection communication system;

[0060] Figure 2 Schematic diagram of the generation process of the fine synchronization sequence based on the Barker code;

[0061] Figure 3 Schematic diagram of the synchronization process of the tag synchronization module. DETAILED DESCRIPTION

[0062] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0063] Example 1:

[0064] Aiming at the problem that the existing backscatter communication system cannot realize multi-tag synchronous access, the present invention provides a backscatter communication high-precision synchronization technology that can resist wake-up delay.

[0065] The present invention relates to the fields of low-power communication, time domain synchronization, and wireless communication. The present invention provides a high-precision synchronization technology for backscatter communication that is resistant to wake-up delays. The technology comprises the following steps: Step S1: Before transmitting a data frame, a transmitter in a backscatter communication system synchronizes with a tag by transmitting a control frame. The control frame contains a coarse synchronization sequence and a fine synchronization sequence based on a Barker code that is resistant to wake-up delays. Step S2: The tag's wake-up module uses the coarse synchronization sequence for coarse synchronization through envelope detection and other methods, and wakes up the tag's fine synchronization module after synchronization is complete. Step S3: After a certain delay, the tag's synchronization module wakes up and can still use the fine synchronization sequence for more precise synchronization, aligning the tag with the data frame in the time domain. In a multi-tag backscatter communication system, synchronization between tags is crucial. This process can be achieved by synchronizing all tags with the transmitter. As an IoT node, the tag operates with ultra-low power consumption, and the synchronization process is similar: the tag utilizes a nW-level wake-up module to monitor environmental signals to maintain ultra-low power consumption. Upon detecting the coarse synchronization sequence, the μW-level synchronization module wakes up. This wake-up process introduces a certain delay, which affects the subsequent fine synchronization process.

[0066] According to the present invention, a high-precision synchronization method for backscatter communication against wake-up delay is provided. Figure 1-Figure 3 Shown, including:

[0067] Step S1: transmitting a control frame to synchronize with the tag, the control frame including a coarse synchronization sequence and a fine synchronization sequence;

[0068] Specifically, in step S1:

[0069] Step S1.1: Generate a bit sequence for identifying the order according to a preset number of synchronization times N;

[0070] Step S1.2: performing an XOR or XOR operation on the generated sequence identifier sequence and the preset Barker code bit by bit to generate a synchronization sequence;

[0071] Step S1.3: splicing the generated synchronization sequence with the preset equal-length gap sequence to form a complete fine synchronization sequence;

[0072] Step S1.4: Add the generated fine synchronization sequence to the control frame. The transmitter in the reflection communication system transmits the control frame before transmitting the data frame to achieve synchronization with the tag.

[0073] Specifically, the step S1.1 includes: the number of high-precision synchronization times N is not limited, and the length of a single sequence identifier is

[0074] The step S1.2 includes: the preset Barker code does not limit the Barker code length;

[0075] The step S1.3 comprises: separating two adjacent sequence identifiers using the preset equal-length gap sequence so that they do not affect each other when calculating the correlation coefficient;

[0076] There are two designs for equal-length gap sequences: the first is all 0s or all 1s, suitable for synchronization modules whose decision threshold stability exceeds the preset standard; the second is alternating 0s and 1s, suitable for synchronization modules whose decision threshold dynamically adjusts with environmental signals.

[0077] The step S1.4 includes: the reflection communication system does not limit the number of tag nodes, and can be a single node or multiple nodes, wherein the number of nodes in the multi-node reflection communication system is determined by the hardware characteristics of the analog circuit of the hardware.

[0078] Step S2: The tag wake-up module performs coarse synchronization using the coarse synchronization sequence, and wakes up the tag synchronization module after synchronization is completed;

[0079] Step S3: After waking up, the tag synchronization module uses the fine synchronization sequence to synchronize with the data frame in the time domain.

[0080] Specifically, in step S3:

[0081] Step S3.1: The tag's synchronization module is awakened after a delay and starts synchronization;

[0082] Step S3.2: The synchronization module uses the decision circuit to demodulate the fine synchronization sequence to achieve analog-to-digital conversion;

[0083] Step S3.3: The bit sequence obtained by analog-to-digital conversion is input to multiple Barker code correlators in the digital circuit. A single correlator uses the Barker code to perform an exclusive-OR or exclusive-OR operation on the input sequence. The obtained results are then bitwise summed and bitwise negated and then summed to obtain two correlation results, PC and NC, respectively.

[0084] Step S3.4: PC and NC are compared with the thresholds respectively to obtain two binary results P and N. When the sum of P and N is 0, it is determined that the transmitted bit is invalid. When the sum of P and N is 1, it is determined that the transmitted bit is equal to N or P. When all bits are determined to be valid, all bits are concatenated to obtain a single sequence identifier.

[0085] Step S3.5: After obtaining the sequence identifier, the tag and the control frame are aligned in the time domain, and the timer in the synchronization module starts timing, waiting for the control frame to be transmitted. When the data frame arrives, the tag starts modulation.

[0086] Specifically, the step S3.1 includes: the wake-up delay generation factors include the WuRx wake-up receiver and the energy acquisition circuit;

[0087] Step S3.3 includes: wherein the number of Barker code correlators depends on the number of bits of a single sequence identifier symbol. When the number of bits is X, the bit sequence input to the correlator has a total of X segments, each segment length equal to the Barker code length, and correlation results are calculated by the X Barker code correlators in sequence;

[0088] When the fine synchronization sequence is generated by using the exclusive OR or exclusive OR operation, the correlator adopts the exclusive OR or exclusive OR operation;

[0089] The step S3.4 includes: the threshold is a constant value, which is determined according to the length of the Barker code and actual conditions, and the maximum threshold of the Y-bit Barker code is Y.

[0090] Example 2:

[0091] Example 2 is a preferred example of Example 1 and is used to illustrate the present invention in more detail.

[0092] The present invention also provides a high-precision synchronization system for backscatter communication that can combat wake-up delays. The high-precision synchronization system for backscatter communication that can combat wake-up delays can be implemented by executing the process steps of the high-precision synchronization method for backscatter communication that can combat wake-up delays. That is, those skilled in the art can understand the high-precision synchronization method for backscatter communication that can combat wake-up delays as a preferred implementation of the high-precision synchronization system for backscatter communication that can combat wake-up delays.

[0093] According to the present invention, a high-precision synchronization system for backscatter communication that resists wake-up delay is provided, comprising:

[0094] Module M1: transmits control frames to synchronize with tags. The control frames contain coarse synchronization sequences and fine synchronization sequences.

[0095] Specifically, in the module M1:

[0096] Module M1.1: Generates a bit sequence to identify the order according to the preset number of synchronizations N;

[0097] Module M1.2: Perform XOR or XOR operations on the generated sequence identifier sequence and the preset Barker code bit by bit to generate a synchronization sequence;

[0098] Module M1.3: Splice the generated synchronization sequence with the preset equal-length gap sequence to form a complete fine synchronization sequence;

[0099] Module M1.4: Add the generated fine synchronization sequence to the control frame. The transmitter in the reflection communication system synchronizes with the tag by transmitting the control frame before transmitting the data frame.

[0100] Specifically, the module M1.1 includes: the number of high-precision synchronization times N is not limited, and the length of a single sequence identifier is

[0101] The module M1.2 includes: the preset Barker code does not limit the Barker code length;

[0102] The module M1.3 includes: the preset equal-length gap sequence separates two adjacent order identifier symbols so that they do not affect each other when calculating the correlation coefficient;

[0103] There are two designs for equal-length gap sequences: the first is all 0s or all 1s, suitable for synchronization modules whose decision threshold stability exceeds the preset standard; the second is alternating 0s and 1s, suitable for synchronization modules whose decision threshold dynamically adjusts with environmental signals.

[0104] The module M1.4 includes: the reflection communication system does not limit the number of tag nodes, and can be a single node or multiple nodes, wherein the number of nodes in the multi-node reflection communication system is determined by the analog circuit hardware characteristics of the hardware.

[0105] Module M2: The tag wake-up module uses the coarse synchronization sequence to perform coarse synchronization, and wakes up the tag synchronization module after synchronization is completed;

[0106] Module M3: After waking up, the tag synchronization module uses the fine synchronization sequence to synchronize with the data frame in the time domain.

[0107] Specifically, in the module M3:

[0108] Module M3.1: The tag's synchronization module is awakened after a delay and starts synchronization;

[0109] Module M3.2: The synchronization module uses the decision circuit to demodulate the fine synchronization sequence and realize analog-to-digital conversion;

[0110] Module M3.3: The bit sequence obtained by analog-to-digital conversion is input into multiple Barker code correlators in the digital circuit. A single correlator uses the Barker code to perform an exclusive-OR or exclusive-OR operation on the input sequence. The resulting results are then bitwise summed and bitwise negated and then summed to obtain two correlation results, PC and NC, respectively.

[0111] Module M3.4: Compare PC and NC with the thresholds respectively to obtain two binary results P and N. When the sum of P and N is 0, the transmitted bit is determined to be invalid. When the sum of P and N is 1, the transmitted bit is determined to be equal to N or P. When all bits are determined to be valid, all bits are concatenated to obtain a single sequence identifier.

[0112] Module M3.5: After obtaining the sequence identifier, the tag and the control frame are aligned in the time domain. The timer in the synchronization module starts timing, waiting for the control frame to be transmitted. When the data frame arrives, the tag starts modulation.

[0113] Specifically, the module M3.1 includes: the wake-up delay generation factors include WuRx wake-up receiver and energy acquisition circuit;

[0114] The module M3.3 includes: wherein the number of Barker code correlators depends on the number of bits of a single sequence identifier. When the number of bits is X, the bit sequence input to the correlator has a total of X segments, each segment length is equal to the Barker code length, and correlation results are calculated by the X Barker code correlators in sequence;

[0115] When the fine synchronization sequence is generated by using the exclusive OR or exclusive OR operation, the correlator adopts the exclusive OR or exclusive OR operation;

[0116] The module M3.4 includes: the threshold is a constant value, which is determined according to the length of the Barker code and actual conditions, and the maximum threshold of the Y-bit Barker code is Y.

[0117] Example 3:

[0118] Example 3 is a preferred example of Example 1 and is used to illustrate the present invention in more detail.

[0119] According to the present invention, a high-precision synchronization technology for backscatter communication that combats wake-up delay is provided, comprising:

[0120] Step S1: Before transmitting a data frame, the transmitter in the reflection communication system synchronizes with the tag by transmitting a control frame. The control frame includes a coarse synchronization sequence and a fine synchronization sequence based on a Barker code that can resist wake-up delay.

[0121] Step S2: The nW-level wake-up module of the tag performs coarse synchronization using a coarse synchronization sequence by means of envelope detection or the like, and wakes up the μW-level synchronization module of the tag after synchronization is completed;

[0122] Step S3: The synchronization module of the tag is awakened after a certain delay and can still use the fine synchronization sequence to perform higher-precision synchronization and align with the data frame in the time domain.

[0123] Preferably, the step S1 includes:

[0124] Step S1.1: Generate a bit sequence for identifying the order according to a preset high-precision synchronization number N. For example, when N=8, the generated order identification sequence is 000, 001, ..., 111;

[0125] Step S1.2: Perform an XOR or XOR operation on the generated sequence identifier sequence and the preset Barker code bit by bit to generate a synchronization sequence. For example, the XOR operation of 001 and the 11-bit Barker code (11100010010) will generate its corresponding synchronization sequence 11100010010 11100010010 00011101101;

[0126] Step S1.3: Concatenate the generated synchronization sequence with a preset gap sequence of equal length to form a complete fine synchronization sequence. For example, when the preset gap sequence is a 33-bit all-0 sequence, the complete synchronization sequence corresponding to 001 is 1110001001011100010010 00011101101 00…0 (33 bits of 0), i.e., each sequence corresponds to a 66-bit fine synchronization sequence.

[0127] Step S1.4: Add the generated fine synchronization sequence to the control frame. The transmitter in the reflection communication system transmits the control frame before transmitting the data frame to achieve synchronization with the tag.

[0128] Preferably, the step S1.1 comprises: generating a bit sequence for identifying the order according to a preset high-precision synchronization number N;

[0129] The number of high-precision synchronization times N is not limited, and the length of a single sequence identifier is corresponding to

[0130] Preferably, the step S1.2 comprises: performing an XOR or XOR operation on the generated order identification sequence and a preset Barker code bit by bit in sequence to generate a synchronization sequence;

[0131] The preset Barker code does not limit the Barker code length, and includes a 13-bit Barker code, an 11-bit Barker code, and the like.

[0132] Preferably, the step S1.3 comprises: splicing the generated synchronization sequence with a preset equal-length gap sequence to form a complete fine synchronization sequence;

[0133] The preset equal-length gap sequence is used to separate two adjacent order identification symbols so that they do not affect each other when calculating the correlation coefficient. There are two design methods for equal-length gap sequences: the first design method is all 0 or all 1, and the second design method is alternating 0 and 1, that is, 1010...10 or 0101...01. The first design method is suitable for synchronization modules whose decision threshold is basically unchanged. The gap sequence of all 0 or all 1 does not affect the decision threshold of the decision circuit, and the fine synchronization sequence can be demodulated normally. The second design method is suitable for synchronization modules whose decision threshold is dynamically adjusted according to the environmental signal. The gap sequence of all 0 or all 1 will significantly change the decision threshold of the decision circuit, which will seriously affect the subsequent demodulation of the fine synchronization sequence. Therefore, a gap sequence of alternating 0 and 1 is designed for this type of synchronization module.

[0134] Preferably, the step S1.4 comprises: adding the generated fine synchronization sequence to a control frame, and the transmitter in the reflection communication system synchronizes with the tag by transmitting the control frame before transmitting the data frame;

[0135] The reflection communication system does not limit the number of tag nodes and can be a single node or multiple nodes. The number of nodes in a multi-node reflection communication system can reach hundreds or thousands. The specific number of nodes supported is determined by the analog circuit hardware characteristics of the hardware, including oscillator accuracy, impedance network reflection coefficient accuracy, multiple access protocol, etc.

[0136] Preferably, step S3 includes:

[0137] Step S3.1: The tag's synchronization module is awakened after a certain delay and starts synchronization;

[0138] Step S3.2: The synchronization module uses the decision circuit to demodulate the fine synchronization sequence to achieve analog-to-digital conversion;

[0139] Step S3.3: The bit sequence obtained by analog-to-digital conversion is input to multiple Barker code correlators in the digital circuit. A single correlator uses the Barker code to perform an exclusive-OR or exclusive-OR operation on the input sequence. The obtained results are then bitwise summed and bitwise negated and then summed to obtain two correlation results, PC and NC, respectively.

[0140] Step S3.4: PC and NC are compared with the thresholds respectively to obtain two binary results P and N. When the OR value of P and N is 0, it is determined that the transmitted bit is invalid. When the OR value of P and N is 1, it is determined that the transmitted bit is equal to N (inclusive OR correlation) or P (exclusive OR correlation). When all bits are determined to be valid, all bits are concatenated to obtain a single sequence identifier.

[0141] Step S3.5: After obtaining the sequence identifier, the tag is aligned with the control frame in the time domain. The timer in the synchronization module starts timing, waiting for the control frame to be transmitted. When the data frame arrives, the tag starts modulation.

[0142] Preferably, the step S3.1 includes: the synchronization module of the tag is awakened after a certain delay and starts synchronization;

[0143] The wake-up delay may come from the WuRx wake-up receiver, or from other factors that may cause the wake-up delay, such as the energy acquisition circuit.

[0144] Preferably, step S3.3 comprises: inputting the bit sequence obtained by analog-to-digital conversion into a plurality of Barker code correlators in a digital circuit; a single correlator performs an exclusive-OR or exclusive-OR operation on the input sequence using the Barker code; and performing bitwise summation and bitwise negation followed by summation to obtain two correlation results PC and NC, respectively;

[0145] The number of Barker code correlators depends on the number of bits in a single sequence identifier. For example, if the number of bits is 3, the bit sequence input to the correlator has three segments, each equal to the Barker code length. The correlation results are calculated sequentially by three Barker code correlators. When the fine synchronization sequence is generated using XOR / XOR operations, the correlators use XOR / XOR operations.

[0146] Preferably, step S3.4 includes: comparing PC and NC with thresholds respectively to obtain two binary results P and N; when the value of P and N is 0, it is determined that the transmitted bit is an invalid bit; when the value of P and N is 1, it is determined that the transmitted bit is equal to N (inclusive OR correlation) or P (exclusive OR correlation); when all determined bits are valid, all bits are concatenated to obtain a single sequence identifier;

[0147] The threshold is a constant value, which is determined according to the length of the Barker code and actual conditions. For example, the maximum threshold of an 11-bit Barker code can be 11.

[0148] Example 4:

[0149] Example 4 is a preferred example of Example 1 and is used to illustrate the present invention in more detail.

[0150] According to the present invention, a high-precision synchronization technology for backscatter communication that combats wake-up delay is provided, comprising:

[0151] Step S1: Before transmitting a data frame, the transmitter in the reflection communication system synchronizes with the tag by transmitting a control frame. The control frame includes a coarse synchronization sequence and a fine synchronization sequence based on a Barker code that can resist wake-up delay.

[0152] Step S2: The nW-level wake-up module of the tag performs coarse synchronization using a coarse synchronization sequence by means of envelope detection or the like, and wakes up the μW-level synchronization module of the tag after synchronization is completed;

[0153] Step S3: The synchronization module of the tag is awakened after a certain delay and can still use the fine synchronization sequence to perform higher-precision synchronization and align with the data frame in the time domain.

[0154] Specifically, step S1 includes:

[0155] Step S1.1: The reflection communication system sets the number of high-precision synchronizations to 8, and generates a sequence identifier sequence of 000, 001, ..., 111;

[0156] Step S1.2: Perform an XOR operation on the generated sequence identifier sequence bit by bit with the 11-bit Barker code to generate a synchronization sequence. For example, the sequence identifier 001 corresponds to 11100010010 11100010010 00011101101;

[0157] Step S1.3: Concatenate the generated synchronization sequence with an equal-length all-zero gap sequence to form a complete fine synchronization sequence. For example, the complete synchronization sequence corresponding to 001 is 11100010010 11100010010 00011101101 00…0 (33 bits of 0). Each sequence corresponds to a 66-bit fine synchronization sequence.

[0158] Step S1.4: Add the generated fine synchronization sequence with a total length of 528 to the control frame. The transmitter in the reflection communication system synchronizes with the tag by transmitting the control frame before transmitting the data frame.

[0159] Specifically, step S3 includes:

[0160] Step S3.1: The tag's synchronization module is awakened after a certain delay and starts synchronization;

[0161] Step S3.2: The synchronization module uses the decision circuit to demodulate the fine synchronization sequence to achieve analog-to-digital conversion;

[0162] Step S3.3: The bit sequence obtained by analog-to-digital conversion is input into three Barker code correlators in the digital circuit. Each correlator uses the Barker code to perform an exclusive-OR operation with the input sequence. The obtained results are then bitwise summed and bitwise negated and then summed to obtain two correlation results, PC and NC, respectively.

[0163] Step S3.4: Compare PC and NC with the thresholds respectively to obtain two binary results P and N. When the sum of P and N is 0, it is determined that the transmitted bit is invalid. When the sum of P and N is 1, it is determined that the transmitted bit is equal to N. When all bits are determined to be valid, all bits are concatenated to obtain a single sequence identifier.

[0164] Step S3.5: After obtaining the sequence identifier, the tag is aligned with the control frame in the time domain. The timer in the synchronization module starts timing, waiting for the control frame to be transmitted. When the data frame arrives, the tag starts modulation.

[0165] More specifically, if Figure 1 As shown, all tags in the reflection communication system are aligned with the control frame in the time domain through the above steps, and then use their own timers to count, wait for the control frame to be transmitted, and synchronize access when the data frame arrives to start modulating data.

[0166] Example 5:

[0167] Example 5 is a preferred example of Example 1 and is used to illustrate the present invention in more detail.

[0168] According to the present invention, a high-precision synchronization technology for backscatter communication that combats wake-up delay is provided, comprising:

[0169] Step S1: Before transmitting a data frame, the transmitter in the reflection communication system synchronizes with the tag by transmitting a control frame. The control frame includes a coarse synchronization sequence and a fine synchronization sequence based on a Barker code that can resist wake-up delay.

[0170] Step S2: The nW-level wake-up module of the tag performs coarse synchronization using a coarse synchronization sequence by means of envelope detection or the like, and wakes up the μW-level synchronization module of the tag after synchronization is completed;

[0171] Step S3: The synchronization module of the tag is awakened after a certain delay and can still use the fine synchronization sequence to perform higher-precision synchronization and align with the data frame in the time domain.

[0172] Specifically, step S1 includes:

[0173] Step S1.1: The reflection communication system sets the number of high-precision synchronizations to 6, and generates a sequence identifier sequence of 000, 001, ..., 101;

[0174] Step S1.2: Perform bit-by-bit XOR operations on the generated sequence identifier sequence and the 11-bit Barker code to generate a synchronization sequence. For example, the sequence identifier 001 corresponds to 00011101101 00011101101 11100010010;

[0175] Step S1.3: Concatenate the generated synchronization sequence with a sequence of alternating gaps of equal length, each of which is 0 and 1, to form a complete fine synchronization sequence. For example, the complete synchronization sequence corresponding to 001 is 00011101101 00011101101 11100010010 0101…0 (33 alternating bits). Each sequence corresponds to a 66-bit fine synchronization sequence.

[0176] Step S1.4: Add the generated fine synchronization sequence with a total length of 396 to the control frame. The transmitter in the reflection communication system synchronizes with the tag by transmitting the control frame before transmitting the data frame.

[0177] Specifically, step S3 includes:

[0178] Step S3.1: The tag's synchronization module is awakened after a certain delay and starts synchronization;

[0179] Step S3.2: The synchronization module uses the decision circuit to demodulate the fine synchronization sequence to achieve analog-to-digital conversion;

[0180] Step S3.3: The bit sequence obtained by analog-to-digital conversion is input into three Barker code correlators in the digital circuit. A single correlator performs an exclusive-OR operation on the Barker code and the input sequence. The obtained results are then subjected to bitwise summation and bitwise negation followed by summation to obtain two correlation results, PC and NC, respectively.

[0181] Step S3.4: Compare PC and NC with the thresholds respectively to obtain two binary results P and N. When the sum of P and N is 0, it is determined that the transmitted bit is invalid. When the sum of P and N is 1, it is determined that the transmitted bit is equal to N. When all bits are determined to be valid, all bits are concatenated to obtain a single sequence identifier.

[0182] Step S3.5: After obtaining the sequence identifier, the tag is aligned with the control frame in the time domain. The timer in the synchronization module starts timing, waiting for the control frame to be transmitted. When the data frame arrives, the tag starts modulation.

[0183] Those skilled in the art will appreciate that, in addition to implementing the system, device, and various modules provided by the present invention in purely computer-readable program code, it is entirely possible to implement the same program in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, embedded microcontrollers, and the like by logically programming the method steps. Therefore, the system, device, and various modules provided by the present invention can be considered a hardware component, and the modules included therein for implementing various programs can also be considered structures within the hardware component; the modules for implementing various functions can also be considered both software programs for implementing the method and structures within the hardware component.

[0184] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A high-precision synchronization method for backscatter communication to combat wake-up delay, characterized in that: include: Step S1: transmitting a control frame to synchronize with the tag, the control frame including a coarse synchronization sequence and a fine synchronization sequence; Step S2: The tag wake-up module performs coarse synchronization using the coarse synchronization sequence, and wakes up the tag synchronization module after synchronization is completed; Step S3: After waking up, the tag synchronization module uses the fine synchronization sequence to synchronize with the data frame in the time domain; In step S1: Step S1.1: Generate a bit sequence for identifying the order according to a preset number of synchronization times N; Step S1.2: performing an XOR or XOR operation on the generated sequence identifier sequence and the preset Barker code bit by bit to generate a synchronization sequence; Step S1.3: splicing the generated synchronization sequence with the preset equal-length gap sequence to form a complete fine synchronization sequence; Step S1.4: Add the generated fine synchronization sequence to the control frame. The transmitter in the reflection communication system synchronizes with the tag by transmitting the control frame before transmitting the data frame. In step S3: Step S3.1: The tag's synchronization module is awakened after a delay and starts synchronization; Step S3.2: The synchronization module uses the decision circuit to demodulate the fine synchronization sequence to achieve analog-to-digital conversion; Step S3.3: The bit sequence obtained by analog-to-digital conversion is input to multiple Barker code correlators in the digital circuit. A single correlator uses the Barker code to perform an exclusive-OR or exclusive-OR operation on the input sequence. The obtained results are then bitwise summed and bitwise negated and then summed to obtain two correlation results, PC and NC, respectively. Step S3.4: PC and NC are compared with the thresholds respectively to obtain two binary results P and N. When the sum of P and N is 0, it is determined that the transmitted bit is invalid. When the sum of P and N is 1, it is determined that the transmitted bit is equal to N or P. When all bits are determined to be valid, all bits are concatenated to obtain a single sequence identifier. Step S3.5: After obtaining the sequence identifier, the tag and the control frame are aligned in the time domain, and the timer in the synchronization module starts timing, waiting for the control frame to be transmitted. When the data frame arrives, the tag starts modulation.

2. The high-precision synchronization method for backscatter communication against wake-up delay according to claim 1, characterized in that: The step S1.1 includes: the number of high-precision synchronization times N is not limited, and the length of a single sequence identifier is corresponding to The step S1.2 includes: the preset Barker code does not limit the Barker code length; The step S1.3 comprises: separating two adjacent sequence identifiers using the preset equal-length gap sequence so that they do not affect each other when calculating the correlation coefficient; There are two designs for equal-length gap sequences: the first is all 0s or all 1s, suitable for synchronization modules whose decision threshold stability exceeds the preset standard; the second is alternating 0s and 1s, suitable for synchronization modules whose decision threshold dynamically adjusts with environmental signals. The step S1.4 includes: the reflection communication system does not limit the number of tag nodes, and can be a single node or multiple nodes, wherein the number of nodes in the multi-node reflection communication system is determined by the hardware characteristics of the analog circuit of the hardware.

3. The high-precision synchronization method for backscatter communication against wake-up delay according to claim 1, characterized in that: The step S3.1 includes: the wake-up delay generation factors include the WuRx wake-up receiver and the energy acquisition circuit; Step S3.3 includes: wherein the number of Barker code correlators depends on the number of bits of a single sequence identifier symbol. When the number of bits is X, the bit sequence input to the correlator has a total of X segments, each segment length equal to the Barker code length, and correlation results are calculated by the X Barker code correlators in sequence; When the fine synchronization sequence is generated by using the exclusive OR or exclusive OR operation, the correlator adopts the exclusive OR or exclusive OR operation; The step S3.4 includes: the threshold is a constant value, which is determined according to the length of the Barker code and actual conditions, and the maximum threshold of the Y-bit Barker code is Y.

4. A high-precision synchronization system for backscatter communication that combats wake-up delay, characterized in that: include: Module M1: transmits control frames to synchronize with tags. The control frames contain coarse synchronization sequences and fine synchronization sequences. Module M2: The tag wake-up module uses the coarse synchronization sequence to perform coarse synchronization, and wakes up the tag synchronization module after synchronization is completed; Module M3: After waking up, the tag synchronization module uses the fine synchronization sequence to synchronize with the data frame in the time domain; In the module M1: Module M1.1: Generates a bit sequence to identify the order according to the preset number of synchronizations N; Module M1.2: Perform XOR or XOR operations on the generated sequence identifier sequence and the preset Barker code bit by bit to generate a synchronization sequence; Module M1.3: Splice the generated synchronization sequence with the preset equal-length gap sequence to form a complete fine synchronization sequence; Module M1.4: Add the generated fine synchronization sequence to the control frame. The transmitter in the reflection communication system synchronizes with the tag by transmitting the control frame before transmitting the data frame. In the module M3: Module M3.1: The tag's synchronization module is awakened after a delay and starts synchronization; Module M3.2: The synchronization module uses the decision circuit to demodulate the fine synchronization sequence and realize analog-to-digital conversion; Module M3.3: The bit sequence obtained by analog-to-digital conversion is input into multiple Barker code correlators in the digital circuit. A single correlator uses the Barker code to perform an exclusive-OR or exclusive-OR operation on the input sequence. The resulting results are then bitwise summed and bitwise negated and then summed to obtain two correlation results, PC and NC, respectively. Module M3.4: Compare PC and NC with the thresholds respectively to obtain two binary results P and N. When the sum of P and N is 0, the transmitted bit is determined to be invalid. When the sum of P and N is 1, the transmitted bit is determined to be equal to N or P. When all bits are determined to be valid, all bits are concatenated to obtain a single sequence identifier. Module M3.5: After obtaining the sequence identifier, the tag and the control frame are aligned in the time domain. The timer in the synchronization module starts timing, waiting for the control frame to be transmitted. When the data frame arrives, the tag starts modulation.

5. The high-precision synchronization system for backscatter communication with resistance to wake-up delay according to claim 4, characterized in that: The module M1.1 includes: the number of high-precision synchronization times N is not limited, and the length of a single sequence identifier is corresponding to The module M1.2 includes: the preset Barker code does not limit the Barker code length; The module M1.3 includes: the preset equal-length gap sequence separates two adjacent order identifier symbols so that they do not affect each other when calculating the correlation coefficient; There are two designs for equal-length gap sequences: the first is all 0s or all 1s, suitable for synchronization modules whose decision threshold stability exceeds the preset standard; the second is alternating 0s and 1s, suitable for synchronization modules whose decision threshold dynamically adjusts with environmental signals. The module M1.4 includes: the reflection communication system does not limit the number of tag nodes, and can be a single node or multiple nodes, wherein the number of nodes in the multi-node reflection communication system is determined by the analog circuit hardware characteristics of the hardware.

6. The high-precision synchronization system for backscatter communication with resistance to wake-up delay according to claim 4, characterized in that: The module M3.1 includes: the wake-up delay generation factors include WuRx wake-up receiver and energy acquisition circuit; The module M3.3 includes: wherein the number of Barker code correlators depends on the number of bits of a single sequence identifier. When the number of bits is X, the bit sequence input to the correlator has a total of X segments, each segment length is equal to the Barker code length, and correlation results are calculated by the X Barker code correlators in sequence; When the fine synchronization sequence is generated by using the exclusive OR or exclusive OR operation, the correlator adopts the exclusive OR or exclusive OR operation; The module M3.4 includes: the threshold is a constant value, which is determined according to the length of the Barker code and actual conditions, and the maximum threshold of the Y-bit Barker code is Y.

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