Passive backscatter communication methods, systems, tags, and readers

Abstract

The application discloses a passive backscattering communication method, system, tag and reader, and relates to the technical field of wireless communication. The passive backscattering communication method is applied to a tag and comprises the following steps: receiving a first synchronization signal and downlink signaling sent by a reader; determining a downlink time basic unit length based on the length of the first synchronization signal, and determining the uplink time basic unit length of uplink signaling in a target time period based on the downlink time basic unit length and an indication field in the downlink signaling; wherein the downlink signaling at least comprises Select signaling and / or Query signaling, and the indication field is a newly-added field in the Select signaling and / or Query signaling; the length of the first synchronization signal is a positive integer multiple of the downlink time basic unit length; and at least one uplink signaling is sent to the reader in the target time period according to the determined uplink time basic unit length, so as to guarantee the function of uplink and downlink communication.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a passive backscatter communication method, system, tag, and reader. Background Technology

[0002] Ultra-high frequency RFID (Radio Frequency Identification) technology is a low-cost, low-power passive backscattering wireless communication technology widely used in logistics, asset management, and anti-counterfeiting of goods.

[0003] This system generally includes two types of communication devices: readers and tags. There may be one or more tags within the coverage area of ​​a reader. The reader first sends downlink signaling to each tag. The communication link from the reader to the tag is generally called the downlink or forward link. Each tag decides whether to send uplink signaling to the reader in response based on its own actual situation. The communication link from the tag to the reader is generally called the uplink or reverse link.

[0004] When the tag sends signaling to the reader, it uses passive backscattering technology, meaning that the tag itself does not generate a carrier wave, but modulates the information on the carrier wave sent by the reader in a backscattering manner.

[0005] In traditional UHF RFID technology, downlink signaling is transmitted using PIE (Pulse Interval Encoding). This means that for the information to be transmitted, both bit 0 and bit 1 contain a high-level and a low-level waveform, but the waveform lengths (or high-level lengths) differ. For example, bit 0 corresponds to a shorter waveform (or high-level) length, while bit 1 corresponds to a longer waveform (or high-level) length.

[0006] Traditional UHF RFID technology can only support a coverage distance of about ten meters at most. At this coverage distance, the tag can easily find the rising edge in the downlink signaling, and thus perform tasks such as counting the number of sampling points and measuring length.

[0007] When traditional UHF RFID technology is further extended to support longer coverage distances (such as 100m), the accuracy of downlink signaling measurement or statistics will decrease due to the weaker received signal, which in turn affects the uplink and downlink communication functions. Summary of the Invention

[0008] The purpose of this invention is to provide a passive backscatter communication method, system, tag, and reader to ensure uplink and downlink communication functionality.

[0009] According to a first aspect of the present invention, a passive backscatter communication method is provided, applied to a tag, the method comprising: receiving a first synchronization signal and downlink signaling transmitted by a reader; determining a downlink time basic unit length based on the length of the first synchronization signal, and determining an uplink time basic unit length of uplink signaling within a target time period based on the downlink time basic unit length and an indication field in the downlink signaling; wherein the downlink signaling includes at least Select signaling and / or Query signaling, and the indication field is a newly added field in the Select signaling and / or Query signaling; the length of the first synchronization signal is a positive integer multiple of the downlink time basic unit length; and transmitting at least one uplink signaling to the reader within the target time period according to the determined uplink time basic unit length.

[0010] According to a second aspect of the present invention, a passive backscatter communication method is provided, applied to a reader / writer. The method includes: sending a first synchronization signal and downlink signaling to a tag, such that the tag determines a downlink time basic unit length based on the length of the first synchronization signal, and determines an uplink time basic unit length of uplink signaling within a target time period based on the downlink time basic unit length and an indication field in the downlink signaling; wherein the downlink signaling includes at least Select signaling and / or Query signaling, and the indication field is a newly added field in the Select signaling and / or Query signaling; the length of the first synchronization signal is a positive integer multiple of the downlink time basic unit length; and receiving at least one uplink signaling sent by the tag within the target time period according to the uplink time basic unit length.

[0011] According to a third aspect of the present invention, a passive backscatter communication system is provided, the system comprising a tag and a reader / writer; wherein the reader / writer is configured to send a first synchronization signal and downlink signaling to the tag; the tag is configured to receive the first synchronization signal and the downlink signaling, determine a downlink time basic unit length based on the length of the first synchronization signal, and determine an uplink time basic unit length for uplink signaling within a target time period based on the downlink time basic unit length and an indication field in the downlink signaling; wherein the downlink signaling includes at least Select signaling and / or Query signaling, and the indication field is a newly added field in the Select signaling and / or Query signaling; the length of the first synchronization signal is a positive integer multiple of the downlink time basic unit length; the tag is further configured to send at least one uplink signaling to the reader / writer within the target time period according to the determined uplink time basic unit length.

[0012] According to a fourth aspect of the present invention, a tag is provided, including a computer program, which, when executed by a processor, implements the passive backscatter communication method described in the first aspect above.

[0013] According to a fifth aspect of the present invention, a reader / writer is provided, comprising a computer program that, when executed by a processor, implements the passive backscatter communication method described in the second aspect above.

[0014] In the solution provided by this invention, by sending a first synchronization signal before downlink signaling, the tag can determine the length of the uplink time basic unit by obtaining the signal length, thus avoiding the problem of inaccurate length measurement statistics caused by inaccurate tag detection of rising edge during long-distance coverage. Furthermore, the uplink time basic unit length is determined according to the downlink time basic unit length and the indication field in the downlink signaling, so that the tag and the reader can communicate accurately according to the determined uplink and downlink time basic unit lengths, thereby ensuring the uplink and downlink communication function.

[0015] By setting the indicator field, the length of the uplink time basic unit can be controlled, enabling uplink signaling to support multiple transmission rates, maintaining a certain degree of flexibility, and allowing for the setting of higher transmission rates. Compared to transmitting at a fixed minimum rate, this also helps improve transmission efficiency. During communication, downlink signaling is shorter, such as tens of bits, and frequently occurring signaling may even be only a few bits, while uplink signaling is much longer, such as tag-reported IDs and sensor data, which often approach hundreds of bits. This means that uplink occupies a larger proportion of the overall communication time, so increasing the uplink rate helps improve overall transmission efficiency.

[0016] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the first passive backscatter communication method provided in this embodiment of the invention.

[0018] Figure 2 This is a schematic diagram of a signaling transmission timing provided in an embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of a sliding correlation calculation method provided in an embodiment of the present invention;

[0020] Figure 4 This is a schematic diagram of the first type of synchronization signal comparison provided in the embodiments of the present invention;

[0021] Figure 5This is a schematic diagram of the second type of synchronization signal comparison provided in an embodiment of the present invention;

[0022] Figure 6 This is a waveform diagram of the first type of related result provided in the embodiments of the present invention;

[0023] Figure 7 This is a waveform diagram of the second related result provided in the embodiments of the present invention;

[0024] Figure 8 This is a schematic diagram of the first synchronization signal structure provided in the embodiments of the present invention;

[0025] Figure 9 This is a schematic diagram of the second synchronization signal structure provided in an embodiment of the present invention;

[0026] Figure 10 This is a waveform diagram of the third related result provided in the embodiments of the present invention;

[0027] Figure 11 This is a waveform diagram of the fourth related result provided in the embodiments of the present invention;

[0028] Figure 12 This is a waveform diagram of the fifth related result provided in the embodiments of the present invention;

[0029] Figure 13 This is a waveform diagram of the sixth related result provided in the embodiments of the present invention;

[0030] Figure 14 This is a flowchart illustrating the second passive backscatter communication method provided in this embodiment of the invention.

[0031] Figure 15 This is a schematic diagram of a passive backscatter communication system provided in an embodiment of the present invention. Detailed Implementation

[0032] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0033] The passive backscatter communication method and system of the present invention are described below with reference to the accompanying drawings.

[0034] In one embodiment of the present invention, see Figure 1 A passive backscatter communication method is provided for use with tags, including:

[0035] Step S101: Receive the first synchronization signal and downlink signaling sent by the reader / writer;

[0036] Step S102: Determine the downlink time basic unit length based on the length of the first synchronization signal, and determine the uplink time basic unit length of the uplink signaling within the target time period based on the downlink time basic unit length and the indication field in the downlink signaling; wherein, the downlink signaling includes at least Select signaling and / or Query signaling, and the indication field is a newly added field in Select signaling and / or Query signaling; the length of the first synchronization signal is a positive integer multiple of the downlink time basic unit length;

[0037] Step S103: Send at least one uplink signaling to the reader within the target time period according to the determined uplink time basic unit length.

[0038] In step S101, if the first synchronization signal sent by the reader is detected, the first synchronization signal and the downlink signaling sent by the reader after the first synchronization signal are received, and the length of the downlink time basic unit is determined based on the length of the first synchronization signal.

[0039] like Figure 1 As shown, before step S101 begins, the reader sends downlink signaling and a first synchronization signal to the tag. The reader can send various downlink signaling to the tag; examples are given below.

[0040] The Select signaling is primarily used by the reader to select tags and change the internal flag states of the tags. This signaling includes fields such as MemBank (memory area), Pointer (starting address), Length, Mask, Target, Action, and Truncate. MemBank indicates which memory area to use, Pointer indicates the starting address of that memory area, and Mask matches the content of the memory area starting from Pointer, essentially filtering the content of the tag's MemBank. The Mask field has a variable length, ranging from 0 to 255 bits, with the specific length indicated by the Length field. When a tag matches the content of the Mask field, it is considered selected by the Select signaling; otherwise, the tag is not selected. The Target field indicates a specific session of the tag. There are four sessions within a tag, designated by numbers 0-3. Each session corresponds to a flag bit, and each flag bit has two states (e.g., state A and state B). The Action field indicates what changes to be made to the flag bit state corresponding to that session of the tag. For example, the flag bit state corresponding to the session of all selected tags is set to A, and the flag bit state corresponding to the session of unselected tags is set to B, etc. The Truncate field indicates whether the tag sends the complete EPC (Electronic Product Code) or a truncated portion. After receiving the Select signaling, the tag only performs internal processing and does not send any uplink response signaling. The Select signaling is of variable length.

[0041] Query (Inventory) signaling: Primarily used for reader initialization and initiating a new round of tag reading. This signaling includes fields such as Session and Target, as well as some uplink parameter fields. The Session and Target fields indicate which tags meet the conditions to participate in the current round of reader reading. For example, if the Session field is 0 and the Target field is A, then tags with a Session 0 flag of state A need to participate in the current round of reading. Based on the uplink parameter fields, the tag can determine the encoding method, encoding rate, synchronization header length, and uplink response slot number (starting from 0) to use when sending subsequent uplink information. After receiving the Query signaling, the tag determines that it needs to participate in the current round of reading, and if the uplink response slot number is 0, it responds. The Query signaling is of fixed length.

[0042] QueryRep (Repeated Read) signaling: Primarily used to trigger a new time slot during a round of reading. Upon receiving a Query signaling message, the tag determines if it needs to participate in the current round of reading. If the uplink response time slot sequence number is greater than 0, the tag does not respond initially. Each new QueryRep signaling message is considered a new time slot, and an uplink response is only initiated when the previously determined uplink response time slot sequence number arrives. Specifically, the tag selects a 16-bit random number (RN16) and sends it to the reader. The QueryRep signaling message is of fixed length.

[0043] The Ack (Acknowledgement) signaling is primarily used by the reader to acknowledge receipt of the tag's uplink response. This signaling contains a 16-bit random number previously sent by the tag. Upon receiving the Ack signaling, if the tag determines that the 16-bit random number it received matches the 16-bit random number it previously sent to the reader, it will initiate a further uplink response. Specifically, the tag will send back part or all of its ID (such as EPC, Electronic Product Code) to the reader. When the reader receives part or all of this tag ID, it considers the basic reading of the tag complete. Optionally, the reader can also perform other further operations on the tag, such as reading or writing to a specific storage area of ​​the tag, which are not directly related to this invention and will not be elaborated upon. The Ack signaling is of fixed length.

[0044] In a round of tag reading process, QueryRep signaling is the most frequently sent signaling by the reader, followed by Ack signaling. Query and Select signaling are sent less frequently. Query signaling is sent only once in each round, while Select signaling is optional.

[0045] The reader can directly send Query signals to the tags to select a tag in a specific session and state for a new reading process; alternatively, it may first send one or more Select signals to select the tag and change the internal flag state of the tag in a specific session, and then send Query signals to select a tag in a specific session and state for a new reading process.

[0046] The first synchronization signal is used by the tag to determine the start time of downlink signaling. For example... Figure 2 As shown in the figure, the positions from left to right represent the timing, with the left side representing earlier times. The end time of the first synchronization signal corresponds to the start time of the downlink signaling.

[0047] In step S104, at least one uplink signaling is sent according to the uplink time basic unit length, including:

[0048] The transmission duration of a unit bit of data is determined based on the determined uplink time basic unit length;

[0049] Send at least one uplink signaling according to the determined transmission duration.

[0050] That is, the settings: ,in, Indicates the duration of transmission for a single bit. It is a preset positive integer. This indicates the length of the basic unit of uplink time.

[0051] In one embodiment, the target time period can be set as follows: from the time the first uplink signaling is sent after receiving the first synchronization signal and downlink signaling, to the time the next downlink signaling with a new indication field is received. One or more uplink signaling messages may exist within the target time period.

[0052] If the new indicator field has a different value than the previous indicator field, then the uplink time basic unit length and downlink time basic unit length shall be recalculated according to the value of the new indicator field using the method in steps S102-S103.

[0053] In one embodiment, the downlink time basic unit length can be determined as follows:

[0054]

[0055] in, Indicates the length of the first synchronization signal; Represents a preset positive integer; This indicates the length of the downlink time basic unit.

[0056] The value can be 8, 16, 32, 64, etc. When K takes the form of an integer power of 2, it makes... Easier to calculate. In other embodiments, Other values ​​other than integer powers of 2 can also be obtained, but this embodiment of the invention does not limit this.

[0057] After the tag detects the first synchronization signal, the length of the first synchronization signal can be obtained. The length of the first synchronization signal can be represented by the number of sampling points in the sampling point sequence.

[0058] The following examples illustrate two implementation methods for determining the length of the uplink time basic unit of the uplink signaling to be sent.

[0059] The first implementation method is as follows:

[0060]

[0061] in, Indicates the length of the basic unit of uplink time; Indicates the segmentation ratio; Indicates the length of the downlink time basic unit; This indicates the value indicated by the field.

[0062] The second implementation method is as follows:

[0063]

[0064] in, Indicates the length of the basic unit of uplink time; Indicates the length of the downlink time basic unit; This indicates the value indicated by the field.

[0065] In the aforementioned embodiment, the tag received a first synchronization signal. Then, it can be substituted into the formula of any of the above implementation methods to calculate. .

[0066] The DR (Divide Ratio) is represented by a corresponding field in downlink signaling. Specifically, in Query signaling, the DR field is 1 bit, where 0 represents 8 and 1 represents 64 / 3.

[0067] Specifically, the value of the indication field is determined based on the segmentation ratio in the downlink signaling; that is, the value indicated by the indication field. The value of the DR field determines the value. When the DR field is different, the same indicator field can also correspond to different values ​​P, as detailed in subsequent embodiments. If changes are possible, This can also be modified accordingly, allowing for the support of more different transmission rates in the uplink transmission from the tag to the reader, which can be selected according to actual needs, further increasing flexibility. The use of the DR field reuses mechanisms from existing technologies, resulting in better compatibility.

[0068] In contrast, the second implementation method obtains the result in one step. The calculation process is simpler.

[0069] The following describes how step S102 sets the indication field in the downlink signaling.

[0070] Method 1: Add an indication field to the Query signaling and define it as follows: Fields. Indicator fields can be added anywhere in the Query signaling message; the location can be pre-specified via the communication protocol. The Query signaling message is mandatory for each inventory check and is sent via Query signaling. The field does not require additional signaling, resulting in minimal overhead.

[0071] Method 2: Add an indication field to the Select signaling. Send via Select signaling. When only a query signal is sent for inventory, the field remains in the traditional mode. When a query signal is preceded by a message carrying... When using the Select signaling for a field, the new mode applies. This has no impact on the Query signaling and offers better protocol compatibility.

[0072] Specifically, since other types of signaling are shorter and occur more frequently than Select and Query signaling—for example, QueryRep signaling is sent every time a new time slot is triggered during a round of reading, while Query signaling is only sent once when a new round of reading begins—adding a P field to other types of signaling would increase the overall overhead due to the increased number of times the P field is sent. Furthermore, since the P field only needs to be indicated once and can be reused, it is unnecessary to repeatedly carry the same parameter in frequently sent signaling. Therefore, using Select and Query signaling is more resource-efficient.

[0073] In both of the above methods, adding a new indication field means adding a new field while keeping all the fields in the original signaling unchanged.

[0074] As can be seen from the above, in the solution provided by the embodiments of the present invention, by sending a first synchronization signal before the downlink signaling, the tag can determine the length of the uplink time basic unit by obtaining the signal length, thus avoiding the problem of inaccurate length measurement statistics caused by inaccurate detection of the rising edge of the tag when covering long distances. Furthermore, the uplink time basic unit length is determined according to the downlink time basic unit length and the indication field in the downlink signaling, so that the tag and the reader can communicate accurately according to the determined uplink and downlink time basic unit lengths, thereby ensuring the uplink and downlink communication function.

[0075] By setting the indicator field, the length of the uplink time basic unit can be controlled, enabling uplink signaling to support multiple transmission rates, maintaining a certain degree of flexibility, and allowing for the setting of higher transmission rates. Compared to transmitting at a fixed minimum rate, this also helps improve transmission efficiency. During communication, downlink signaling is shorter, such as tens of bits, and frequently occurring signaling may even be only a few bits, while uplink signaling is much longer, such as tag-reported IDs and sensor data, which often approach hundreds of bits. This means that uplink occupies a larger proportion of the overall communication time, so increasing the uplink rate helps improve overall transmission efficiency.

[0076] In one embodiment, the tag detects the first synchronization signal sent by the reader in the following manner:

[0077] Receive the target signal sent by the reader; generate a second synchronization signal, which contains the same sequence as the first synchronization signal; calculate the sliding correlation result between the second synchronization signal and the target signal; if there is a peak value in the sliding correlation result that is greater than a preset correlation threshold, then it is determined that the first synchronization signal was detected in the received target signal.

[0078] The target signal can be any signal sent by the reader. Since detection has not yet been performed, the received target signal may contain the first synchronization signal, or it may be downlink signaling or other types of information without a synchronization signal.

[0079] The first and second synchronization signals contain the same sequence, which can be predefined in the communication protocol between the reader and the tag.

[0080] For example, the parameter M in the aforementioned embodiments can also be preset in the communication protocol.

[0081] In one embodiment, the sliding correlation result between the second synchronization signal and the target signal can be calculated in the following manner:

[0082] For sequences extracted from different positions in the target signal, the sequence included in the second synchronization signal is multiplied by each sequence at each sampling point to obtain the sum of the products of each sampling point of each sequence, which is used as the sliding correlation result.

[0083] Specifically, a sequence of equal-length sampling points is extracted from the received target signal, multiplied one by one by the sampling points in the sequence of the second synchronization signal, and then summed to obtain the result. A sampling point refers to the level value of the signal sampled at a certain moment.

[0084] The summation result is compared with a preset detection threshold. If it is greater than or equal to the detection threshold, the first synchronization signal is considered to have been detected. Otherwise, the first synchronization signal is considered not to have been detected. One or more sampling points are moved backward in the received target signal to extract another segment of equal length sequence and the process is continued.

[0085] If the first synchronization signal is detected in the target signal, it will reach its maximum value when calculating the summation result because it contains a sequence identical to the second synchronization signal. Setting the detection threshold to a value lower than this maximum value will allow for the detection of the first synchronization signal.

[0086] like Figure 3 As shown, the tag receives the target signal and obtains a sequence of received signal sampling points, i.e., a sequence of the target signal. This sequence contains at least one bit, and each bit is represented by the value of at least one sampling point. Different sampling points correspond to different times.

[0087] The target signal itself consists of high and low levels, corresponding to bits 1 and 0. If it is bit 1, i.e., a high-level sampling point, the tag value is +1; if it is bit 0, representing a low-level sampling point, the tag value is -1. This applies to both the received signal sampling point sequence and the second synchronization signal sampling point sequence.

[0088] When a synchronization signal sampling point sequence identical to the second synchronization signal sampling point sequence is received, the product at each sampling point is 1, and the sum equals the number of sampling points in the second synchronization signal sampling point sequence, resulting in a peak value. When the received signal sampling point sequence differs significantly from the second synchronization signal sampling point sequence, more -1 values ​​will appear in the product of each sampling point, and the sum will be smaller than the aforementioned peak value. This sampling point sequence correlation method, compared to the rising edge detection method, has a higher signal detection success rate at long distances and can more accurately detect the position of the first synchronization signal.

[0089] In an embodiment of the present invention, the synchronization signal comprises a sequence of 0 and 1 bits, and each bit is composed of at least one sampling point, i.e., the above-mentioned sampling point sequence.

[0090] In this case, a second synchronization signal containing multiple sets of sequences can be generated, with a different number of sampling points in each set of sequences;

[0091] Correspondingly, the sub-correlation results of the sliding correlation between each set of sequences in the second synchronization signal and the target signal can be calculated, and the sliding correlation result can be determined based on each sub-correlation result.

[0092] The tag periodically samples according to its own clock to obtain sampling points, but the tag's clock may be inaccurate, and there will be a certain offset above and below the reference clock frequency. That is, the second synchronization signal sampling point sequence may contain more or fewer sampling points.

[0093] Thus, when performing sliding correlation calculations using sampling points, even if each bit of the first and second synchronization signals is the same, the sliding correlation result may still be inaccurate because the number of sampling points may differ under offset conditions.

[0094] Therefore, generating multiple sets of sequences and making the number of sampling points in the multiple sets of sequences different can cope with the situation where the number of sampling points increases or decreases due to the offset.

[0095] In this way, the sub-correlation results of the sliding correlation between each set of sequences and the target signal can be calculated in parallel using multiple paths. The calculation method is similar to that of the sliding correlation results in the previous embodiment, with the only difference being the sequences. The set of sequences with the largest sub-correlation results is selected, and the number of sampling points of this set of sequences is taken as the length of the second synchronization signal. The sub-correlation results of this set of sequences are then taken as the sliding correlation results.

[0096] In one embodiment, the first synchronization signal includes a sequence with a predetermined number of 0 bits at the beginning.

[0097] In practice, there are instances where the received first synchronization signal is incomplete or distorted. For example, while the reader is sending the first synchronization signal, the digital part of the tag may have already started working, but the analog part may not be ready yet. In this case, the digital part will receive a low-level signal. By the time the analog part is ready and starts working, it may have already missed the first 2 to 3 bits of the first synchronization signal.

[0098] like Figure 4 As shown. If the tag misses the beginning of the first synchronization signal, the received first synchronization signal sequence includes the sequence of sampled points from the entire first synchronization signal excluding the beginning portion. The second synchronization signal sequence is the complete second synchronization signal.

[0099] Assuming the first synchronization signal is 32 bits and the second synchronization signal has 10 samples per bit, there are a total of 320 samples. The first two bits (20 samples) are missed. If the tag doesn't miss any samples and the received first and second synchronization signal sequences are identical, the sliding correlation result is 320 if the product at each sample point is 1. If two bits are missed, and in the worst case, the first two bits of the second synchronization signal are both 1, the tag defaults to receiving bit -1, so the product of the first two bits is -1, resulting in a sliding correlation result of 320 – 20 - 20 = 280. The correlation result is reduced, equivalent to a performance penalty in tag synchronization.

[0100] In this case, the first synchronization signal has a preset number of 0 bits at the beginning. For example, the first 2 or 3 bits are 0. In the above embodiment, in the case of missing or not missing, the first two bits of the first synchronization signal are both -1. The missing part will not reduce the overall correlation peak, thus avoiding the loss of tag synchronization performance.

[0101] When the form of the second synchronization signal is not properly selected, multiple correlation peaks may be generated during the correlation process, leading to false detections. For example... Figure 5 As shown, the sampling point sequence of the second synchronization signal is divided into several segments of equal length, denoted as A~H.

[0102] When A=B=C=D=…=H, the correlation results of the second synchronization signal's sampling point sequence at two positions in the diagram may both be peak values. The correlation results between the second synchronization signal's sampling point sequence at the first position (B~H) and the received synchronization signal's sampling point sequence, and the sliding correlation results between the second position (A~G) and the received first synchronization signal's sampling point sequence, may be equal. In this case, the timing of receiving the first synchronization signal is inaccurate.

[0103] A=B=C=D=…=H, at this time the second synchronization signal is a multiple repetition of the same subsequence A.

[0104] At this point, the difference in the overall correlation results lies only in the correlation results between the first position A and the missed portion, and the correlation results between the second position H and the beginning portion of the data. If the beginning portion of the data happens to be all 0s, the two correlation results will be exactly the same, resulting in two identical peaks; if the beginning portion of the data happens to be exactly the same as or partially the same as A, the latter correlation result may even be larger. The tag may mistakenly identify the latter position as the first synchronization signal, causing false detections, resulting in the beginning portion of the data also being missed, affecting the decoding of subsequent data, and reducing reliability.

[0105] Therefore, in one scenario, the first synchronization signal can be configured to include a sequence that does not contain repeating subsequences. A sequence that does not contain repeating subsequences means that the arrays formed by the values ​​of each sampling point in a subsequence extracted from different positions within the first synchronization signal sequence are different. In this way, the first synchronization signal is not composed of multiple repetitions of a short subsequence. This avoids the problem of multiple equal sliding correlation results caused by the repetition of short sequences.

[0106] Furthermore, in the case of subsequence repetition in the above embodiments, it can be further assumed that the bits corresponding to subsequence A are [1 0]. Without missing any sampling points in the sequence of received synchronization signals, the only maximum peak value is 160, and there are two second-largest peak values, both 140, such as... Figure 6 As shown in the figure. The horizontal axis represents time in microseconds, and the vertical axis represents the peak value of the sliding correlation result.

[0107] When two bits are missed, and the beginning of the data is the same as the missed part (both are low), the relevant results are as follows: Figure 7 As shown. Similar to Figure 6 The horizontal axis represents time, and the vertical axis represents the peak value of the sliding correlation result. As can be seen... Figure 7 Two maximum peak values ​​appeared, both at 140, indicating that the labels were more likely to be falsely detected.

[0108] Therefore, in one case, the autocorrelation result of the sequence included in the first synchronization signal can be set to have a single peak; in another case, the maximum peak value of the autocorrelation result of the sequence included in the first synchronization signal can be set to be no less than twice the second largest peak value.

[0109] Here, autocorrelation refers to the sliding correlation between the sequence of the first synchronization signal and itself. It is also known that the second synchronization signal has the same sequence as the first synchronization signal. Under the influence of the above autocorrelation results, the sliding correlation result between the second synchronization signal and the first synchronization signal also has a single peak value. Furthermore, when the maximum peak value in the autocorrelation result is not less than twice the second largest peak value, the maximum peak value in the sliding correlation result is also more obvious.

[0110] As shown above, using a sequence with good autocorrelation as the first synchronization signal can reduce the probability of multiple correlation peaks occurring when the first synchronization signal at the beginning is missed, thereby reducing the possibility of false tag detection.

[0111] The above solution is illustrated below through a specific embodiment.

[0112] In one possible implementation, the downlink time basic unit = 25μs. The reader sends a first synchronization signal before each downlink signaling message. The first synchronization signal is a fixed sequence with a length L = 32 × (K=32). The reader adds an indication field with a length of 2 bits to the Query signaling. = ×P / DR, the specific definition of the value of P and the different values ​​of P under different P values The values ​​are shown in Table 1 below. Assume the length of a single bit in the tag's uplink signal. = (M=1), then the reader / writer will... Receive uplink signals.

[0113] Table 1

[0114]

[0115] Assume the tag sampling clock frequency is 1.28MHz. The length of the first synchronization signal sequence detected before the downlink signaling is L = 800μs (1024 sampling points). =L / 32 (K=32) = 25μs (32 sampling points). The tag decodes the Query command sent by the reader. Assuming that the indicator field bit is 10 and the DR field bit is 0, the DR field value is 8. According to the field definition section in the table above, the P field value is 8. =25μs (32 sampling points). Assuming a single bit length for tag uplink signaling. = ( =1) =25μs (32 sampling points), the label is based on Send uplink signaling.

[0116] One possible implementation, downlink time basic unit =25μs. The reader sends a first synchronization signal before each downlink signaling message. The first synchronization signal is a fixed sequence with a length of... =32× (K=32). The reader adds an indicator field to the Query command, with a length of 2 bits. = ×P, the specific value definition of P and the different values ​​of P under different P values The values ​​are shown in Table 2 below. Assume the length of a single bit in the tag's uplink signal. = ( =1), then the reader / writer will... Receive uplink signaling.

[0117] Table 2

[0118]

[0119] Assume the tag sampling clock frequency is 1.28MHz. The tag detects the first synchronization signal sequence before downlink signaling, with a detected length of L = 800μs (1024 sampling points). =32, then =L / 32=25μs (32 sampling points). The tag decodes the query signaling sent by the reader. Assuming that the P field bit is 10 and the DR field bit is 0, the DR field value is 8. According to the field definition section in the table above, the P field value is 1. = ×P = 25μs (32 sampling points). Assume the length of a single bit in the tag's uplink signal. = ( =1) =25μs (32 sampling points), the label is based on Send uplink signals.

[0120] In the above embodiments, similarly, It can also take other values ​​such as 8, 16, 64, etc. It can also take other values ​​such as 2, 4, 8, etc. It can also take other values ​​such as 12.5, 6.25, 3.125, 50, etc. The signaling sent for the P field can also be Select signaling, etc.

[0121] Alternatively, the query signaling can be ignored. The influence of fields, if involved in formulas The DR field can be fixed to a single value. For example, if the default value is 8, then each table can retain only rows with a DR value of 0; if the default value is 64 / 3, then each table can retain only rows with a DR value of 64 / 3. The P field can also have other lengths, such as 3 bits, 4 bits, etc. It can support a wider range of possible values.

[0122] For the first synchronization signal, one possible approach is [00011100111010001101110100100101], where K = 32. Assume each bit has 10 sampling points.

[0123] On the one hand, this sequence is not generated by repeated short sequences, exhibiting good autocorrelation performance with only a single peak in the correlation result, as shown in the autocorrelation results. Figure 10 As shown. The only maximum peak value is 320, and the other peak values ​​do not exceed 50. The maximum peak value is greater than 6 × the second largest peak value.

[0124] On the other hand, the first three bits of the first synchronization signal in this sequence are all 0, which can effectively avoid the problem of reduced correlation results caused by missing the beginning of the first synchronization signal sampling point sequence. Assume that the tag generates three different lengths of second synchronization signal sampling point sequences with 9, 10, and 11 sampling points per bit, respectively, and performs three-way parallel correlation. The correlation result when the first synchronization signal sampling point sequence corresponds to 10 sampling points per bit is as follows... Figure 11 As shown. Solid lines, dashed lines, and dotted lines correspond to the correlation results for 9, 11, and 10 sampling points per bit, respectively. The correlation results for not missing the beginning of the first synchronization signal sampling point sequence and for missing the first 2 or 3 bits are the same, with a maximum peak value of 320, which does not decrease.

[0125] Alternatively, the first synchronization signal may also include the reverse of the above sequence, [1 0 1 0 0 1 0 0 1 0 11 1 0 1 1 0 0 0 1 0 1 1 1 0 0 1 1 1 0 0 0], where the first two bits are not [0 0] and the first three bits are not [0 0 0]. The only maximum peak value in the autocorrelation result is 320, and the remaining peak values ​​do not exceed 50.

[0126] The reverse order uses the correlation results obtained through 3-way parallel processing. Figure 12 Solid lines, dashed lines, and dotted lines correspond to the results of 9, 11, and 10 sampling points per bit, respectively, with a maximum peak value of 300.

[0127] The correlation results of missing the first 3 bits of the sampling sequence of the first synchronization signal in reverse order are as follows: Figure 13 As shown, the maximum peak value is 280.

[0128] For the reverse-order first synchronization signal, since the first 2 and 3 bits are not all 0, the maximum correlation peak will decrease when the first 2 or 3 bits are missed, thus affecting the tag's synchronization performance. However, for the forward-order first synchronization signal, since the first 3 bits are all 0, the maximum correlation peak will not decrease even if the first 2 or 3 bits are missed, thus avoiding any impact on the tag's synchronization performance.

[0129] Another possible approach is that the first synchronization signal can be [00001100111010001101110100100101], and the method for calculating the sliding correlation result is similar to the above, with a maximum peak value of 320.

[0130] In one embodiment, the sequence included in the first synchronization signal is obtained from more than one candidate sequence of the same length. For example, if sequences A and B of the same length are preset as candidate sequences, then for each time the reader sends the first synchronization signal, one of sequences A and B is selected to generate the first synchronization signal containing the selected candidate sequence.

[0131] In this case, the length of the downlink time basic unit can be determined as follows;

[0132]

[0133] in, Indicates the length of the first synchronization signal; Represents a preset positive integer; Indicates the length of the downlink time basic unit; Represents sequence parameters, for different sequences The values ​​are different.

[0134] Specifically, The value can be 8, 16, 32, 64, etc. Similar to the aforementioned embodiments, When taking the form of an integer power of 2, It is easier to calculate.

[0135] The value of can be 1, 2, 4, 8, etc. Assume the first synchronization signal contains sequence 1 and sequence 2. For sequence 1, =1, for sequence 2, = 2, When taking the form of an integer power of 2, It is easier to calculate.

[0136] In this case, the following two implementation methods can determine the length of the uplink time basic unit.

[0137] First implementation method:

[0138]

[0139] in, Indicates the length of the basic unit of uplink time; Indicates the segmentation ratio; Indicates the length of the downlink time basic unit; This represents the second sequence parameter, for different candidate sequences. Different values; This indicates the value indicated by the field.

[0140] The second implementation method:

[0141]

[0142] in, Indicates the length of the basic unit of uplink time; Indicates the length of the downlink time basic unit; This represents the second sequence parameter, for different candidate sequences. Different values; This indicates the value indicated by the field.

[0143] The reader follows the sequence parameters Definite The first synchronization signal is sent, the tag receives the first synchronization signal, and after receiving the first synchronization signal, the tag calculates based on the length of the second synchronization signal: = ( / ) / .

[0144] Of the two implementation methods above, These are bit combinations; the same bit combination corresponds to different values ​​in different sequences, such as... For sequence 1, the corresponding value is 1; for sequence 2, the corresponding value is 2, and so on. Alternatively, formally, it can be directly... × writing Then with Similarly, The same combination of bits can have different values ​​for different sequences.

[0145] Of the two implementation methods above, the first method can reuse the mechanism of the DR field in the existing technology and has better compatibility; while the calculation method using the second method is simpler.

[0146] The setting method for the indicator field is the same as that in the previous embodiment. It can be set in the Query signaling or the Select signaling, which will not be described in detail here.

[0147] In one embodiment, when there are two candidate sequences, the sampling points corresponding to the two candidate sequences take opposite values.

[0148] In other words, the two candidate sequences have opposite values ​​at the sampling points corresponding to the same time. Taking sequences A and B as candidate sequences, when the second synchronization signal generated by the tag contains sequence A, if the sequence of the first synchronization signal is A, the maximum peak value can be obtained according to the sliding correlation calculation method in the aforementioned embodiment. However, when detecting B, no peak value that meets the requirements will appear. Therefore, the tag knows that the reader is sending A, and thus uses the second sequence parameter corresponding to A. Calculate the basic unit length of uplink time If the sequence of the first synchronization signal is B, the negative value of the maximum peak value can be obtained according to the calculation method of the aforementioned embodiment. The tag knows that the reader sends B, and then uses the second sequence parameter corresponding to B. Calculate the basic unit length of uplink time .

[0149] As mentioned above, by setting multiple sequences in the first synchronization signal, downlink can also support multiple transmission rates, providing more flexibility. The higher transmission rate, compared to fixed minimum transmission rate, is also conducive to improving transmission efficiency.

[0150] The following specific examples illustrate parameter-based methods. , Implementation method for calculating the basic unit length of uplink and downlink time.

[0151] In one possible implementation, the reader sends a first synchronization signal before each downlink signaling instruction. This first synchronization signal has two different sequences, denoted as Sequence 1 and Sequence 2. The relationship between these two sequences is that they are inverted at sampling points; that is, a bit that is 0 in Sequence 1 has a corresponding bit that is 1 in Sequence 2, and vice versa. The first synchronization signals of both sequences have the same length, L = 32 × × ( = 32). For sequence 1, = 1, = 25μs; for sequence 2, = 2, = 12.5μs. The reader / writer has added an indicator field to the Query command. , It has a length of 2 bits. , and Specific value definitions and different under the value The values ​​are shown in Table 3 below. Assume the length of a single bit in the tag uplink signal. = ( = 1), then the reader / writer will use... Receive uplink signals.

[0152] Table 3

[0153]

[0154] Assume the tag sampling clock frequency is 1.28MHz. The tag detects the first synchronization signal sequence before downlink signaling, and the detected length is L = 800μs (1024 sampling points).

[0155] Assuming the detected sequence by the label is sequence 1, it can be known that = 1, then = / 32 ( = 32) / 1 ( = 1) = 25μs (32 sampling points). The tag decodes the Query signaling sent by the reader. Assuming that the P field bit is 10 and the DR field bit is 0, the DR field value is 8. According to the field definition section in the table above, the P field value is 8 and the O value is 1. = 25μs. Assuming the single bit length of the tag uplink signal. ' = '( = 1) = 25μs, the tag according to 'Send uplink signals.'

[0156] Assuming the detected sequence by the label is sequence 2, it can be known that = 2, then = / 32 ( = 32) / 2 = 12.5μs (16 sampling points). The tag decodes the query signaling sent by the reader, assuming that among them... The field bit is 10. If the field bit is 0, then The field value is 8. According to the field definition in the table above, we know... The field value is 8, and the O value is 2. = 25μs (32 sampling points). Assuming a single bit length of the tag uplink signal. = ( = 1) = 25μs (32 sampling points), the label is based on Send uplink signals.

[0157] In the above implementation methods, the calculation can also be performed. Collaborative writing The table is redefined as shown in Table 4 below. That is, for different sequences, The same bits in a field correspond to different numerical values.

[0158] Table 4

[0159]

[0160] In one possible implementation, the reader sends a first synchronization signal before each downlink signaling instruction. This first synchronization signal has two different sequences, denoted as Sequence 1 and Sequence 2. The relationship between these two sequences is that they are inverted at sampling points; that is, a bit that is 0 in Sequence 1 has a corresponding bit that is 1 in Sequence 2, and vice versa. The first synchronization signals of both sequences are of equal length. = 32 × × ( = 32). For sequence 1, = 1, = 25μs; for sequence 2, = 2, = 12.5μs. The reader / writer adds a new field to the Query command. , It has a length of 2 bits. = × × . and Specific value definitions and different The TUL values ​​for the given ranges are shown in Table 5 below. Assume the single bit length of the tag uplink signal. = ( =1), then the reader / writer will... Receive uplink signals.

[0161] Table 5

[0162]

[0163] Assume the tag sampling clock frequency is 1.28MHz. The tag detects the first synchronization signal sequence before downlink signaling, and the detected length is L = 800μs (1024 sampling points).

[0164] Assuming the detected sequence is sequence 1, we know Q = 1, then... = / 32 ( = 32) / 1 ( = 1) = 25μs (32 sampling points). The tag decodes the query command sent by the reader, assuming that among them... The field bit is 10. If the field bit is 0, then The field value is 8. According to the field definition in the table above, we know... The field value is 1, and the O value is 1. = 25μs (32 sampling points). Assuming a single bit length of the tag uplink signal. = ( = 1) = 25μs (32 sampling points), the label is based on Send uplink signals.

[0165] Assuming the detected sequence by the label is sequence 2, it can be known that = 2, then = / 32 ( = 32) / 2 = 12.5μs (16 sampling points). The tag decodes the query command sent by the reader, assuming that among them... If the field bit is 10 and the DR field bit is 0, then... The field value is 8. According to the field definition in the table above, we know... The field value is 1, and the O value is 2. = 25μs (32 sampling points). Assuming a single bit length of the tag uplink signal. = ( = 1) = 25μs (32 sampling points), the label is based on Send uplink signals.

[0166] In the above implementation methods, the calculation can also be performed. In the formula Collaborative writing ,Right now = × P, the table is redefined as shown in Table 6 below. That is, for different sequences, The same bits in a field correspond to different numerical values.

[0167] Table 6

[0168]

[0169] In the above embodiments, similarly, It can also take other values ​​such as 8, 16, 64, etc. It can also take other values ​​such as 2, 4, 8, etc. It can also be sent with other values ​​such as 12.5, 6.25, and 50. The signaling for a field can also be a Select signaling, etc. The Query signaling can also be ignored. The influence of fields, if involved in formulas It can be fixed to a single value, such as the default value of 8, in which case each table can retain only [the specified value]. Rows with a value of 0; if the default value is 64 / 3, then each table can retain only the rows with a value of 0. The row with a value of 64 / 3. The field can also have other lengths, such as 3 bits, 4 bits, etc. It can support a wider range of possible values. The number of different sequences for the first synchronization signal can also be other possibilities, such as 3, 4, etc. It can support a wider range of possible values.

[0170] Based on the aforementioned embodiments, the P field can be sent in the Select signaling by reusing the Mask variable-length field.

[0171] Specifically, when the current downlink signaling is Select signaling and there are preset special fields in Select signaling, the indication field is determined according to the Mask field in Select signaling.

[0172] The Select signaling contains pre-defined special fields, called special Select signaling, which use parameter values ​​or combinations of values ​​that do not appear in normal Select signaling. For example, special fields include any of the following:

[0173] The Target field can take any one of the values ​​101, 110, or 111.

[0174] The MemBank field with a value of 00;

[0175] A combined field consisting of a Truncate field with a value of 1 and a Target field with a value of any one of 000, 001, 010, or 011;

[0176] The Truncate field has a value of 1 and the MemBank field has a value of either 10 or 11;

[0177] The Pointer field has a value of 01111111 and the MemBank field has a value of 10.

[0178] In one embodiment, the indicator field is determined based on at least one characteristic parameter contained in the Mask field.

[0179] Specifically, for different characteristic parameters, the number of bits they occupy is preset, such as... Figure 8 As shown.

[0180] For example, characteristic parameter x1 occupies y1 bits, characteristic parameter x2 occupies y2 bits, characteristic parameter x3 occupies y3 bits, and so on. The variable-length Mask field is reused. These characteristic parameters are arranged in order. For example, the first y1 bits of the Mask field are fixed as characteristic parameter x1, the next y2 bits are fixed as characteristic parameter x2, and the next y3 bits are fixed as characteristic parameter x3.

[0181] Figure 8 In this context, the specific values ​​for special fields are as described in any of the special fields in the preceding embodiments. Select represents the Select signaling, and Mask represents the Mask field. The following embodiments... Figure 9 The same representation method was also used.

[0182] In other embodiments, the Mask field also includes an indication parameter indicating the presence or absence of each characteristic parameter.

[0183] For example, an indicator parameter with a 1-bit increment for each characteristic parameter can be used to indicate whether that characteristic parameter exists. Figure 9 As shown. For example, for characteristic parameter x1, y1+1 bits are occupied; for characteristic parameter x2, y2+1 bits are occupied; for characteristic parameter x3, y3+1 bits are occupied, and so on. The variable-length Mask field is multiplexed. These characteristic parameters are arranged in order. For example, the first bit of the Mask field indicates whether characteristic parameter x1 exists. If it is 1, it exists. The next y1 bits are characteristic parameter x1; if it is 0, it does not exist. The next bit indicates whether characteristic parameter x2 exists, and so on.

[0184] In embodiments using the Mask field, the indicator field is one of the characteristic parameters, while other characteristic parameters can be used to indicate the encoding type, bit rate, etc., of the uplink signaling sent by the tag.

[0185] As shown above, by directly reusing existing fields of the existing Select signaling, there is no need to define new signaling or add new fields, resulting in better protocol compatibility and lower implementation complexity.

[0186] Furthermore, since the Mask field itself is variable-length, supporting up to 255 bits, it is easier to extend the function when new feature parameters are added by reusing this field to indicate feature parameters.

[0187] The following example illustrates how to use the Mask field to determine the indicator field.

[0188] In one possible implementation, the reader sends a Select signaling message, where the Target field has a value of 101, and the first two bits of the Mask field are used to send the P field. Upon receiving the Select signaling message, the tag finds that the Target field is 101, determines that the Select signaling message is a special Select signaling message used to send characteristic parameters, and obtains the P field from the first two bits of the Mask field.

[0189] Another possible implementation involves the reader sending a Select signaling message, where the Target field is 101, the first bit of the Mask field is 1 (indicating the presence of a P field), and the second and third bits are used to transmit the P field. Upon receiving the Select signaling message, the tag finds that the Target field is 101 and determines that this Select signaling message is a special Select signaling message used to transmit characteristic parameters. Finding that the first bit of the Mask field is 1, it determines that a P field is present and retrieves the P field from the second and third bits of the Mask field.

[0190] In the above embodiments, similarly, the Target field can also be 110, 111, etc., and the P field and the bit indicating the presence of the P field can also be in other positions in the Mask field, such as after several other characteristic parameters (such as the encoding type and code rate of the tag's uplink signal). Indicating special Select signaling can also be achieved by setting the MemBank field to 00, or setting the Target field to one of 000, 001, 010, or 011 and the Truncate field to 1, or setting the MemBank field to one of 10 or 11 and the Truncate field to 1, or setting the MemBank field to 10 and the Pointer field to 01111111, etc.

[0191] In the specific implementations of the above technical solutions, it is exemplarily assumed that the tag's sampling clock frequency of 1.28MHz is without deviation. In the case of deviation, the length of the detected first synchronization signal may be greater than or less than 1024 sampling points, and the formula in the above embodiments is used to calculate the number of sampling points.

[0192] In one embodiment of the present invention, see Figure 14 Furthermore, a passive backscatter communication method is provided for use in a reader / writer, including:

[0193] S1401: Send a first synchronization signal and downlink signaling to the tag, so that the tag determines the downlink time basic unit length based on the length of the first synchronization signal, and determines the uplink time basic unit length of the uplink signaling within the target time period based on the downlink time basic unit length and the indication field in the downlink signaling; wherein, the downlink signaling includes at least Select signaling and / or Query signaling, and the indication field is a newly added field in Select signaling and / or Query signaling; the length of the first synchronization signal is a positive integer multiple of the downlink time basic unit length;

[0194] S1402: During the target time period, receive at least one uplink signaling sent by the tag according to the uplink time basic unit length.

[0195] For passive backscatter communication methods on the reader side, the solutions provided in the following embodiments can also be applied.

[0196] In one embodiment, the length of the downlink time basic unit is determined as follows:

[0197]

[0198] in, This indicates the length of the first synchronization signal; Represents a preset positive integer; This indicates the length of the downlink time basic unit.

[0199] In one embodiment, the length of the uplink time basic unit is determined as follows:

[0200]

[0201] in, Indicates the length of the basic unit of uplink time; Indicates the segmentation ratio; This indicates the length of the downlink time basic unit; This refers to the indicated field.

[0202] In one embodiment, the length of the uplink time basic unit is determined as follows:

[0203]

[0204] in, Indicates the length of the basic unit of uplink time; This indicates the length of the downlink time basic unit; This refers to the indicated field.

[0205] In one embodiment, the first synchronization signal includes a sequence that does not contain repeating subsequences;

[0206] And / or,

[0207] The autocorrelation result of the sequence included in the first synchronization signal has a single peak.

[0208] And / or,

[0209] The maximum peak value in the autocorrelation result of the sequence included in the first synchronization signal is not less than twice the second largest peak value.

[0210] In one embodiment, the sequence included in the first synchronization signal is obtained from more than one candidate sequence of the same length;

[0211] The length of the downlink time basic unit is determined in the following manner;

[0212]

[0213] in, This indicates the length of the first synchronization signal; Represents a preset positive integer; This indicates the length of the downlink time basic unit; Represents sequence parameters, for different candidate sequences The values ​​are different.

[0214] In one embodiment, when there are two candidate sequences, the bit values ​​corresponding to the two candidate sequences are opposite.

[0215] From the receiving perspective, the tag side sees sampling points, while from the transmitting perspective, the reader / writer side sees bits. Therefore, the bit values ​​corresponding to the two candidate sequences on the reader / writer side are opposite, which is equivalent to the sampling points corresponding to the two candidate sequences on the tag side having opposite values ​​in the aforementioned embodiment.

[0216] In one embodiment, the length of the uplink time basic unit is determined as follows:

[0217]

[0218] in, Indicates the length of the basic unit of uplink time; Indicates the segmentation ratio; This indicates the length of the downlink time basic unit; This represents the second sequence parameter, for different candidate sequences. Different values; This refers to the indicated field.

[0219] In one embodiment, the length of the uplink time basic unit is determined as follows:

[0220]

[0221] in, Indicates the length of the basic unit of uplink time; This indicates the length of the downlink time basic unit; This represents the second sequence parameter, for different candidate sequences. Different values; This refers to the indicated field.

[0222] In one embodiment, when the downlink signaling is a Select signaling and there is a preset special field in the Select signaling, the indication field is determined according to the Mask field in the Select signaling.

[0223] In one embodiment, the special field includes any one of the following:

[0224] The Target field can take any one of the values ​​101, 110, or 111.

[0225] The MemBank field with a value of 00;

[0226] A combined field consisting of a Truncate field with a value of 1 and a Target field with a value of any one of 000, 001, 010, or 011;

[0227] The Truncate field has a value of 1 and the MemBank field has a value of either 10 or 11;

[0228] The Pointer field has a value of 01111111 and the MemBank field has a value of 10.

[0229] In one embodiment, the indication field is determined based on at least one characteristic parameter contained in the Mask field.

[0230] In one embodiment, the Mask field also includes an indication parameter indicating whether each characteristic parameter exists.

[0231] In one embodiment, the value of the indication field is determined based on the segmentation ratio in the downlink signaling.

[0232] The settings of various parameters on the reader end, such as the segmentation ratio (DR) and sequence parameters, as well as the calculation methods of various parameters, such as determining the basic unit length of the uplink time unit of the uplink signaling within the target time period, are similar to the aforementioned embodiment of the passive backscatter communication method applied to tags. The only difference is the execution subject. You can refer to steps S101-S103 in the aforementioned embodiment, which will not be described in detail here.

[0233] In one embodiment of the present invention, see Figure 15 Furthermore, a passive backscatter communication system is provided, the system comprising a tag and a reader / writer; wherein,

[0234] The reader / writer is used to send a first synchronization signal and downlink signaling to the tag;

[0235] The tag is used to receive the first synchronization signal and the downlink signaling, determine the downlink time basic unit length based on the length of the first synchronization signal, and determine the uplink time basic unit length of the uplink signaling within a target time period based on the downlink time basic unit length and the indication field in the downlink signaling; wherein the downlink signaling includes at least Select signaling and / or Query signaling, and the indication field is a newly added field in the Select signaling and / or Query signaling; the length of the first synchronization signal is a positive integer multiple of the downlink time basic unit length;

[0236] The tag is also used to send at least one uplink signaling to the reader within the target time period according to the determined uplink time basic unit length.

[0237] In the solution provided by this invention, by sending a first synchronization signal before downlink signaling, the tag can determine the length of the uplink time basic unit by obtaining the signal length, thus avoiding the problem of inaccurate length measurement statistics caused by inaccurate tag detection of rising edge during long-distance coverage. Furthermore, the uplink time basic unit length is determined according to the downlink time basic unit length and the indication field in the downlink signaling, so that the tag and the reader can communicate accurately according to the determined uplink and downlink time basic unit lengths, thereby ensuring the uplink and downlink communication function.

[0238] By setting the indicator field, the length of the uplink time basic unit can be controlled, enabling uplink signaling to support multiple transmission rates, maintaining a certain degree of flexibility, and allowing for the setting of higher transmission rates. Compared to transmitting at a fixed minimum rate, this also helps improve transmission efficiency. During communication, downlink signaling is shorter, such as tens of bits, and frequently occurring signaling may even be only a few bits, while uplink signaling is much longer, such as tag-reported IDs and sensor data, which often approach hundreds of bits. This means that uplink occupies a larger proportion of the overall communication time, so increasing the uplink rate helps improve overall transmission efficiency.

[0239] In one embodiment of the present invention, a tag is also provided, including a computer program that, when executed by a processor, implements the passive backscatter communication method for the tag described above.

[0240] In one embodiment of the present invention, a reader / writer is also provided, including a computer program that, when executed by a processor, implements the passive backscatter communication method described above for the reader / writer.

[0241] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A passive backscatter communication method, characterized in that, Applied to a label, the method includes: Receive the first synchronization signal and downlink signaling sent by the reader / writer; The downlink time basic unit length is determined based on the length of the first synchronization signal, and the uplink time basic unit length of the uplink signaling within the target time period is determined based on the downlink time basic unit length and the indication field in the downlink signaling; wherein, the downlink signaling includes at least Select signaling and / or Query signaling, and the indication field is a newly added field in the Select signaling and / or Query signaling, or, when the downlink signaling is Select signaling and there is a preset special field in the Select signaling, the indication field is determined according to the Mask field in the Select signaling; the length of the first synchronization signal is a positive integer multiple of the downlink time basic unit length; At least one uplink signaling is sent to the reader within the target time period according to the determined uplink time basic unit length.

2. The method according to claim 1, characterized in that, The length of the downlink time basic unit is determined as follows: in, This indicates the length of the first synchronization signal; Represents a preset positive integer; This indicates the length of the downlink time basic unit.

3. The method according to claim 1, characterized in that, The length of the uplink time basic unit is determined as follows: in, Indicates the length of the basic unit of uplink time; Indicates the segmentation ratio; This indicates the length of the downlink time basic unit; This indicates the value indicated by the indicated field.

4. The method according to claim 1, characterized in that, The length of the uplink time basic unit is determined as follows: in, Indicates the length of the basic unit of uplink time; This indicates the length of the downlink time basic unit; This indicates the value indicated by the indicated field.

5. The method according to claim 1, characterized in that, The tag detects the first synchronization signal sent by the reader in the following manner: Receive the target signal sent by the reader / writer; A second synchronization signal is generated, which contains the same sequence as the first synchronization signal; Calculate the sliding correlation result between the second synchronization signal and the target signal; If the sliding correlation result contains a peak value greater than a preset correlation threshold, then it is determined that the first synchronization signal was detected in the received target signal.

6. The method according to claim 5, characterized in that, The generation of the second synchronization signal includes: A second synchronization signal is generated, which contains multiple sets of sequences, and the number of sampling points in each set of sequences is different; The calculation of the sliding correlation result between the second synchronization signal and the target signal includes: Calculate the sub-correlation results of the sliding correlation between each set of sequences in the second synchronization signal and the target signal, and determine the sliding correlation result based on each sub-correlation result.

7. The method according to claim 1, characterized in that, The first synchronization signal includes a sequence that does not contain repeating subsequences; And / or, The autocorrelation result of the sequence included in the first synchronization signal has a single peak. And / or, The maximum peak value in the autocorrelation result of the sequence included in the first synchronization signal is not less than twice the second largest peak value.

8. The method according to claim 1, characterized in that, The first synchronization signal includes a sequence obtained from more than one candidate sequence of the same length; The length of the downlink time basic unit is determined in the following manner; in, This indicates the length of the first synchronization signal; Represents a preset positive integer; This indicates the length of the downlink time basic unit; Represents sequence parameters, for different candidate sequences The values ​​are different.

9. The method according to claim 8, characterized in that, When two candidate sequences exist, the values ​​at the sampling points corresponding to the two candidate sequences are opposite.

10. The method according to claim 8, characterized in that, The length of the uplink time basic unit is determined as follows: in, Indicates the length of the basic unit of uplink time; Indicates the segmentation ratio; This indicates the length of the downlink time basic unit; This represents the second sequence parameter, for different candidate sequences. Different values; This indicates the value indicated by the indicated field.

11. The method according to claim 8, characterized in that, The length of the uplink time basic unit is determined as follows: in, Indicates the length of the basic unit of uplink time; This indicates the length of the downlink time basic unit; This represents the second sequence parameter, for different candidate sequences. Different values; This indicates the value indicated by the indicated field.

12. The method according to claim 1, characterized in that, The value of the indication field is determined based on the segmentation ratio in the downlink signaling.

13. A passive backscatter communication method, characterized in that, Applied to a reader / writer, the method includes: A first synchronization signal and downlink signaling are sent to the tag, so that the tag determines the downlink time basic unit length based on the length of the first synchronization signal, and determines the uplink time basic unit length of the uplink signaling within the target time period based on the downlink time basic unit length and the indication field in the downlink signaling; wherein, the downlink signaling includes at least Select signaling and / or Query signaling, and the indication field is a newly added field in the Select signaling and / or Query signaling, or, when the downlink signaling is Select signaling and there is a preset special field in the Select signaling, the indication field is determined according to the Mask field in the Select signaling; the length of the first synchronization signal is a positive integer multiple of the downlink time basic unit length; During the target time period, at least one uplink signaling sent by the tag is received according to the length of the uplink time basic unit.

14. The method according to claim 13, characterized in that, The length of the downlink time basic unit is determined as follows: in, This indicates the length of the first synchronization signal; Represents a preset positive integer; This indicates the length of the downlink time basic unit.

15. The method according to claim 13, characterized in that, The length of the uplink time basic unit is determined as follows: in, Indicates the length of the basic unit of uplink time; Indicates the segmentation ratio; This indicates the length of the downlink time basic unit; This indicates the value indicated by the indicated field.

16. The method according to claim 13, characterized in that, The length of the uplink time basic unit is determined as follows: in, Indicates the length of the basic unit of uplink time; This indicates the length of the downlink time basic unit; P indicates the value indicated by the indicator field.

17. The method according to claim 13, characterized in that, The first synchronization signal includes a sequence that does not contain repeating subsequences; And / or, The autocorrelation result of the sequence included in the first synchronization signal has a single peak. And / or, The maximum peak value in the autocorrelation result of the sequence included in the first synchronization signal is not less than twice the second largest peak value.

18. The method according to claim 13, characterized in that, The first synchronization signal includes a sequence obtained from more than one candidate sequence of the same length; The length of the downlink time basic unit is determined in the following manner; in, This indicates the length of the first synchronization signal; Represents a preset positive integer; This indicates the length of the downlink time basic unit; Represents sequence parameters, for different candidate sequences The values ​​are different.

19. The method according to claim 18, characterized in that, When two candidate sequences exist, the corresponding bit values ​​of the two candidate sequences are opposite.

20. The method according to claim 18, characterized in that, The length of the uplink time basic unit is determined as follows: in, Indicates the length of the basic unit of uplink time; DR indicates the segmentation ratio; This indicates the length of the downlink time basic unit; This represents the second sequence parameter, for different candidate sequences. Different values; This indicates the value indicated by the indicated field.

21. The method according to claim 18, characterized in that, The length of the uplink time basic unit is determined as follows: in, Indicates the length of the basic unit of uplink time; This indicates the length of the downlink time basic unit; This represents the second sequence parameter, for different candidate sequences. Different values; This indicates the value indicated by the indicated field.

22. The method according to claim 13, characterized in that, The value of the indication field is determined based on the segmentation ratio in the downlink signaling.

23. A passive backscatter communication system, characterized in that, The system includes tags and readers; wherein... The reader / writer is used to send a first synchronization signal and downlink signaling to the tag; The tag is used to receive the first synchronization signal and the downlink signaling, determine the downlink time basic unit length based on the length of the first synchronization signal, and determine the uplink time basic unit length of the uplink signaling within a target time period based on the downlink time basic unit length and the indication field in the downlink signaling; wherein, the downlink signaling includes at least Select signaling and / or Query signaling, and the indication field is a newly added field in the Select signaling and / or Query signaling, or, when the downlink signaling is Select signaling and there is a preset special field in the Select signaling, the indication field is determined according to the Mask field in the Select signaling; the length of the first synchronization signal is a positive integer multiple of the downlink time basic unit length; The tag is also used to send at least one uplink signaling to the reader within the target time period according to the determined uplink time basic unit length.

24. A tag comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the passive backscatter communication method as described in any one of claims 1-12.

25. A reader / writer, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the passive backscatter communication method as described in any one of claims 13-22.

Images