Rfid near field area reading method and system based on power-response curve calibration

Abstract

This invention relates to the fields of radio frequency identification (RFID) and near-field wireless communication technology, and discloses an RFID near-field area reading method and system based on power-response curve calibration. The method includes: acquiring a preset spatial boundary and a preset total number of tags within the boundary; transmitting radio frequency signals at multiple power levels; receiving tag response data containing at least a responding tag identifier; constructing a power-response rate curve based on the tag response data at each power level; determining the power range where the rate of response increase satisfies a preset growth condition as a critical power range based on the curve, and determining the critical power accordingly; determining the target transmission power based on the desired coverage, critical power, and preset safety margin; performing tag reading at the target transmission power; dividing the responding tags into tags within the boundary and tags outside the boundary based on the spatial location information corresponding to the tag identifier, and verifying the effectiveness of the area definition accordingly. This method can improve the accuracy of RFID near-field area reading.

Description

Technical Field

[0001] This invention relates to the fields of radio frequency identification and near-field wireless communication technology, and in particular to an RFID near-field area reading method and system based on power-response curve calibration. Background Technology

[0002] Currently, radio frequency identification (RFID) technology is widely used in warehousing and logistics, smart manufacturing, retail anti-counterfeiting, and pharmaceutical sorting to automatically identify tags within a target area. RFID devices typically include a reader, a smart chip, an RF front-end, and an antenna. They transmit RF signals and receive tag response data to achieve tag reading and information processing.

[0003] In one existing technology, in near-field reading scenarios, a fixed transmission power of the reader is preset, or the transmission power is set according to empirical parameters, to match the reading / writing range with a preset spatial boundary, and reading is performed based on the tag response result. This method can meet basic reading requirements when environmental conditions are relatively stable.

[0004] However, in practical applications, factors such as the surrounding metal shelves, paper packaging, plastic containers, liquid-containing goods, and the placement, orientation, and number of tags can all change, altering the actual coverage area of ​​the radio frequency signal. When the transmission power is set too high, tags outside the preset spatial boundary may be read, resulting in misreads; conversely, when the transmission power is set too low, tags within the preset spatial boundary may not be read, resulting in missed reads. Using a fixed transmission power or relying on empirical parameters is insufficient to adapt to these changes and fails to balance tag reading coverage within the area with the misread rate of tags outside the area.

[0005] In summary, existing technologies cannot accurately determine the transmission power that matches the preset spatial boundary based on changes in the actual reading environment, leading to missed readings of tags within the preset spatial boundary or misreading of tags outside the preset spatial boundary, thus affecting the accuracy of RFID near-field reading. Summary of the Invention

[0006] This invention provides an RFID near-field area reading method and system based on power-response curve calibration. It determines the target transmission power that matches the preset spatial boundary based on the tag response data at different transmission power levels and verifies the effectiveness of the area definition, thereby improving the reading coverage of tags within the preset spatial boundary and suppressing misreading of tags outside the preset spatial boundary.

[0007] In a first aspect, to solve the above-mentioned technical problems, the present invention provides an RFID near-field region reading method based on power-response curve calibration, comprising: Obtain a preset spatial boundary and a preset total number of tags within the preset spatial boundary, transmit radio frequency signals at multiple transmission power levels, and receive tag response data; the tag response data includes at least the tag identifier of the responding tag; Based on the tag response data received at each of the aforementioned transmission power levels, a power-response rate curve is constructed; Based on the power-response rate curve, the power range in which the rate of response rate change satisfies the preset rate of increase condition is determined as the critical power range, and the critical power is determined based on the critical power range. The target transmit power is determined based on the desired coverage, the critical power, and the preset safety margin. Tag reading is performed at the target transmission power. Based on the spatial location information corresponding to the tag identifier in the read tag response data, the responding tags are divided into tags within a preset spatial boundary and tags outside a preset spatial boundary. The validity of the area definition is verified based on the division results.

[0008] In one optional implementation, transmitting radio frequency signals at multiple transmission power levels and receiving tag response data includes: Multiple transmit power levels are set sequentially with a first power step, and a preset inventory duration is maintained at each transmit power level to obtain initial tag response data; The power range to be refined is determined based on the initial tag response data. Multiple transmit power levels are set within the power range to be refined with a second power step size smaller than the first power step size, and supplementary tag response data is obtained. The initial tag response data and the supplementary tag response data are integrated to obtain tag response data.

[0009] In one optional implementation, constructing a power-response rate curve based on the tag response data received at each of the said transmit power levels includes: Based on the spatial location information corresponding to the tag identifier in the tag response data received at each of the aforementioned transmission power levels, determine the number of response tags within the preset spatial boundary at each of the aforementioned transmission power levels; The response rate is determined based on the ratio of the number of response tags to the total number of preset tags, and the power-response rate curve is constructed with the transmission power corresponding to each transmission power level as the horizontal axis and the response rate as the vertical axis.

[0010] In one optional implementation, determining the power range where the rate of response change satisfies a preset growth condition as a critical power range, and determining the critical power based on the critical power range, includes: Calculate the responsivity increment between adjacent transmit power levels, and the change in responsivity increment between adjacent responsivity increments; When the change in the response rate increment changes from a positive value to a negative value, or when the response rate increment changes from being higher than a preset increment threshold to being lower than the preset increment threshold, the corresponding power range is determined as the critical power range. The critical power is determined based on the responsivity and the change in responsivity increment corresponding to each transmit power level within the critical power range.

[0011] In one optional implementation, determining the target transmit power based on the desired coverage, the critical power, and the preset safety margin includes: Based on the critical power and the preset safety margin, a candidate transmit power range is determined; Based on the power-response rate curve, the transmission power with a response rate that satisfies the desired coverage rate is determined from the candidate transmission power range and is taken as the target transmission power; wherein, the desired coverage rate is used to measure the tag reading target within the candidate transmission power range.

[0012] In one optional implementation, determining the transmit power whose responsivity satisfies the desired coverage from the candidate transmit power range based on the power-response curve includes: Configure the desired coverage rate according to the region reading accuracy requirements of the reading task; The minimum number of response tags is determined based on the expected coverage rate and the preset total number of tags; Within the candidate transmit power range, the lowest transmit power within the preset spatial boundary, where the number of response tags is not less than the minimum number of response tags, is selected as the target transmit power.

[0013] In one optional implementation, verifying the validity of the region delineation based on the division results includes: The actual coverage rate is determined based on the ratio of the number of tags within the preset spatial boundary to the total number of preset tags in the partitioning results, and the misread rate outside the boundary is determined based on the ratio of the number of tags outside the preset spatial boundary to the total number of response tags in the partitioning results. When the actual coverage rate is not lower than the expected coverage rate and the misread rate outside the boundary is not higher than the preset misread rate threshold, the area definition is determined to be valid.

[0014] In another optional implementation, the step of verifying the validity of the region delineation based on the division results further includes: When the actual coverage is lower than the expected coverage, increase the target transmission power; When the actual coverage is not lower than the expected coverage and the out-of-bounds misread rate is higher than the preset misread rate threshold, the target transmit power is reduced. Perform tag reading with the adjusted target transmit power, and verify the validity of the area delineation based on the tag response data read again.

[0015] In another optional implementation, the step of performing tag reading and verifying the validity of area demarcation with the adjusted target transmit power further includes: The absolute values ​​of each adjustment to the target transmit power within multiple consecutive read cycles are accumulated to obtain the cumulative power adjustment. When the cumulative power adjustment exceeds the preset drift threshold, tag response data is reacquired at multiple transmit power levels, the power-response rate curve is reconstructed, and the critical power and the target transmit power are updated.

[0016] Secondly, the present invention provides an RFID near-field area reading system based on power-response curve calibration, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the above-described RFID near-field area reading method based on power-response curve calibration.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention determines the response rate based on tag response data at different transmission power levels, and determines the critical power range based on the response rate increment and the change in response rate increment. This makes the determination of the critical power based on the actual response changes of tags within the target area, rather than a fixed power setting. Determining the target transmission power based on the critical power, desired coverage, and safety margin helps to match the reading range with the preset spatial boundary, improves the reading coverage of tags within the target area, and suppresses misreading of tags outside the boundary.

[0018] (2) The present invention first obtains initial tag response data according to the first power step size, then determines the power range to be refined based on the initial tag response data, and obtains supplementary tag response data within the range according to the second power step size. Since the second power step size is smaller than the first power step size, it can refine the power range where the difference in the number of response tags of adjacent power levels reaches the refinement judgment threshold, thereby improving the accuracy of the power-response rate curve and the determination result of the critical power.

[0019] (3) This invention verifies the effectiveness of area delineation based on actual coverage and misread rate outside the boundary, and increases the target transmission power when the actual coverage is insufficient and decreases the target transmission power when the misread rate outside the boundary exceeds the limit; when the cumulative power adjustment within a continuous reading cycle exceeds the preset drift threshold, the power scan and curve reconstruction are performed again. Thus, the transmission power can be adjusted according to the reading results and environmental changes, reducing the probability of tag missed reading within the preset spatial boundary and tag misread outside the preset spatial boundary. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the RFID near-field region reading method based on power-response curve calibration provided in the first embodiment of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Reference Figure 1 The first embodiment of the present invention provides an RFID near-field region reading method based on power-response curve calibration, including steps S101 to S105, as follows: S101, obtain the preset spatial boundary and the preset total number of tags within the preset spatial boundary, transmit radio frequency signals at multiple transmission power levels, and receive tag response data; the tag response data includes at least the tag identifier of the responding tag; S102, construct a power-response rate curve based on the tag response data received at each of the aforementioned transmission power levels; S103, based on the power-response rate curve, the power range in which the rate of response rate change satisfies the preset rate of response rate change is determined as the critical power range, and the critical power is determined based on the critical power range; S104, determine the target transmission power based on the desired coverage, the critical power, and the preset safety margin; S105, perform tag reading with the target transmission power, divide the responding tags into tags within the preset spatial boundary and tags outside the preset spatial boundary according to the spatial location information corresponding to the tag identifier in the read tag response data, and verify the validity of the area definition based on the division result.

[0023] In step S101, a preset spatial boundary and a preset total number of tags within the preset spatial boundary are obtained, radio frequency signals are transmitted at multiple transmission power levels, and tag response data is received; the tag response data includes at least the tag identifier of the responding tag.

[0024] Before a reading task begins, the upper-level management system sends the RFID reader a preset spatial boundary, a preset tag list, and a preset total number of tags corresponding to the task. The preset tag list records tags pre-registered within the preset spatial boundary, with each tag identifier corresponding to only one tag record in the list. The total number of preset tags within the preset spatial boundary is denoted as N0, which serves as the unified statistical benchmark for subsequent calculations of response rate and actual coverage.

[0025] Each tag record in the preset tag list includes at least a tag identifier and spatial location information. The spatial location information can be represented using one or more of the following methods: two-dimensional coordinates, three-dimensional coordinates, area number, shelf number, shelf number, storage location number, or workstation number. The preset spatial boundary is used to define the target area range of this reading task, and can be represented by a two-dimensional or three-dimensional coordinate range, or by an area code, shelf number, storage location number, or workstation number.

[0026] In one implementation, the spatial location information is pre-written into the tag's user storage area; after the RFID reader reads the tag identifier, it further retrieves the corresponding spatial location information from the tag's user storage area. In another implementation, the upper-level management system maintains a mapping relationship between tag identifiers and spatial location codes; when the tag response data only includes the tag identifier, the RFID reader or the upper-level management system queries the mapping relationship based on the tag identifier to obtain the corresponding spatial location information. By using a preset tag list and spatial location information, it is possible to determine whether the responding tag is located within a preset spatial boundary.

[0027] Within the same reading task, the preset total number of tags, N0, remains constant to ensure that the response rate obtained at different transmission power levels has the same calculation benchmark. When the upper-level management system detects goods entering or leaving the warehouse, changes in tag binding relationships, changes in tag spatial locations, or adjustments to preset spatial boundaries, it updates the preset tag list, spatial location information, and the preset total number of tags, N0, before the next reading task begins. This avoids using a tag count inconsistent with the current reading task as the response rate calculation benchmark.

[0028] The preset scanning power range is determined by the output power range supported by the RFID reader, antenna configuration, target area size, and security constraints of the reading task. The lower limit of the preset scanning power range is denoted as P. min The upper limit is denoted as P. max P min and P maxThe minimum and maximum transmit power allowed for this scan are defined respectively. In this paper, transmit power, power range endpoints, and received signal strength are all expressed in dBm; power step size, safety margin, power adjustment amount, and drift threshold are all expressed in dB; inventory duration and response time are expressed in ms; number of tags is expressed in units; response rate, coverage, false read rate, and their increments are all dimensionless quantities.

[0029] To balance scanning efficiency and power resolution near the critical power level, a coarse scan can be performed first, followed by a fine scan. The power step size for the coarse scan is denoted as ΔP. r The fine scan power step size is denoted as ΔP. f , where ΔP f <ΔP r Coarse scanning is used to obtain the overall trend of tag response changes across the entire preset scan power range, while fine scanning is used to improve the power resolution within the power range to be refined.

[0030] Let P be the i-th coarse scan transmit power level. ri The i-th coarse scan transmit power level is determined according to the following formula: P ri =P min +(i-1)ΔP r , Where i is the index of the coarse scan transmit power level; when P ri ≤P max At that time, a coarse scan is performed. After the coarse scan is completed, the power range to be refined is determined based on the change in the number of response tags at adjacent coarse scan transmit power levels. The lower limit of the power range to be refined is denoted as P. L The upper limit is denoted as P. U P L and P U Determined from adjacent coarse scan transmit power levels.

[0031] Within the power range to be refined, the j-th fine-scan transmit power level is denoted as P. fj Determined according to the following formula: P fj =P L +(j-1)ΔP f , Where j is the sequence number of the fine-scan transmit power level; when P fj ≤P UAt that time, the corresponding fine scan is performed. The power range to be refined is determined based on the difference in the number of response tags corresponding to adjacent coarse scan power levels. The refinement judgment threshold is pre-given in the task configuration; when the difference in the number is not lower than the refinement judgment threshold, the range between the two corresponding coarse scan power levels is determined as the power range to be refined. The refinement judgment threshold is obtained by rounding up the product of the preset total number of tags and the preset refinement ratio. The preset refinement ratio is configured by the upper-level management system according to the allowed inventory fluctuation range, and its value is not less than 0 and not greater than 1.

[0032] Tag inventory is performed at each coarse scan transmission power level and each fine scan transmission power level, and the preset inventory duration corresponding to each transmission power level is uniformly denoted as T. The T is calibrated before the task starts; the same T is used for each transmission power level of the same reading task to make the tag response results of each power level comparable.

[0033] The preset inventory duration is calibrated during trial operation based on the number of tags and communication protocol parameters: Under the same transmission power, the inventory duration is gradually extended. When the number of newly added responding tags after two consecutive extensions does not exceed the preset stable number, the previous inventory duration is determined as the inventory duration for this mission. The preset stable number is obtained by rounding up the product of the preset total number of tags and the preset stable ratio. The preset stable ratio is configured by the upper-level management system according to the allowable inventory fluctuation range. The inventory duration must not exceed the single-level scan duration allowed for the reading mission. Therefore, each power level uses the same time window sufficient to complete the tag response.

[0034] Each response frame is stored in association with at least the current transmit power level, inventory cycle identifier, and tag identifier. Response frames that fail verification, cannot be identified by the tag identifier, or are duplicates are not included in the response tag set. If the same tag returns multiple response messages within the same preset inventory duration, only one tag identifier is retained to avoid duplicate tag counts due to repeated responses from the same tag.

[0035] After completing the coarse and fine scans, the actual transmit power levels involved in curve construction are uniformly denoted as P in ascending order. q Where q is the sequence number of the merged transmit power level. For the q-th transmit power level P q The response tag set R is formed by collecting the received tag identifiers within the preset inventory time T and deduplicating the tag identifiers. q .

[0036] When the fine scan transmit power level is the same as the coarse scan transmit power level, the response tag set obtained from the fine scan is used to replace the corresponding coarse scan transmit power level's response tag set. Since both the coarse and fine scans are performed within the same preset inventory duration T, the replaced response tag set still maintains a consistent statistical caliber. This avoids directly merging the response results of two independent inventory counts, thus preventing the comparison between different transmit power levels from being affected by individual power levels having longer equivalent inventory times.

[0037] The tag response data includes at least the transmission power level and the tag identifier of the responding tag. When the RFID reader can output additional information, it can also record the received signal strength and response time, and save them in association with the tag identifier according to the transmission power level and inventory cycle identifier. For example, the preset scan power range can be 18dBm to 30dBm, and the coarse scan power step ΔP r It can be 2dB, fine scan power step size ΔP f The threshold can be 0.5dB, and the preset inventory count duration T can be 200ms. A coarse scan obtains tag response data corresponding to 18dBm, 20dBm, 22dBm, 24dBm, 26dBm, 28dBm, and 30dBm. If the difference in the number of response tags between any two adjacent power levels in the three coarse scan power levels (24dBm, 26dBm, and 28dBm) is not less than the refinement threshold, then 24dBm to 28dBm is determined as the power range to be refined, and a supplementary scan is performed with a fine scan power step size of 0.5dB.

[0038] In step S102, a power-response rate curve is constructed based on the tag response data received at each of the aforementioned transmit power levels.

[0039] For each transmit power level P q According to the response tag set R q The spatial location information corresponding to each tag identifier is used to filter response tags whose tag identifiers are included in the preset tag list and located within the preset spatial boundary, and the number of the filtered response tags is recorded as N. q N q As the molecule used to calculate the responsivity at this emission power level.

[0040] When determining whether a response tag is located within a preset spatial boundary, if the tag identifier is included in a preset tag list and the corresponding spatial location information falls within the preset spatial boundary, then the response tag corresponding to that tag identifier is counted in N. q If the spatial location information corresponding to the tag identifier is outside the preset spatial boundary, then the response tag will not be counted in N. qIf a tag identifier is not included in the preset tag list but its corresponding spatial location information falls within the preset spatial boundary, the response data for that transmission power level is marked as inconsistent with the list data, and the data for that transmission power level will not be used for power-response curve construction until the preset tag list is updated. If the spatial location information corresponding to a certain response tag cannot be obtained, that response tag will not be included in N. q The response data for that transmission power level is marked as incomplete location data. After supplementing or updating the correspondence between the tag identifier and the spatial location information, the tag inventory for that transmission power level is re-executed. The data for that transmission power level is not used for power-response curve construction until the location data is supplemented.

[0041] The total number of preset tags N0 within the preset spatial boundary is obtained in step S101. N0 serves as a unified benchmark for calculating the response rate of each transmit power level within the same reading task. The q-th transmit power level P... q The corresponding response rate is denoted as C. q And calculate according to the following formula: ; Among them, C q The value ranges from 0 to 1. C q Indicates at the transmit power level P q The percentage of preset labels that generate effective responses within the preset spatial boundaries.

[0042] When the response tag set R q When N is empty, let N be empty. q =0, C q =0. When the response tag set R q If the value is not empty, but all response labels are located outside the preset space boundary, then N is also considered empty. q =0, C q =0. When N0=0, it means that no preset label is configured within the preset spatial boundary, and the calculation benchmark for the response rate cannot be established; at this time, the power-response rate curve construction is not performed, and the upper-level management system reconfirms and reads the task configuration.

[0043] For each transmit power level, record the corresponding transmit power level P. q The number of response tags N within the preset spatial boundary q and response rate C q Arrange the various transmission power levels in ascending order, using P as the power level. q For the x-axis, C q Connecting the coordinate points on the ordinate yields the power-response curve. When adjacent transmit power levels correspond to the same response, the coordinate points corresponding to each transmit power level are still retained.

[0044] For example, when the total number of preset tags N0 within the preset spatial boundary is 100, the corresponding number of response tags N within the preset spatial boundary for 18dBm, 20dBm, 22dBm, 24dBm, 26dBm, 28dBm, and 30dBm are... q The numbers can be 12, 28, 57, 83, 94, 96, and 96 respectively; the corresponding response rates C q The values ​​can be 0.12, 0.28, 0.57, 0.83, 0.94, 0.96, and 0.96, respectively. The power-response rate curve formed by connecting the above coordinate points characterizes the trend of the tag's response rate within the preset spatial boundary as the transmission power increases.

[0045] In step S103, based on the power-response rate curve, the power range in which the rate of response rate change satisfies the preset rate of response rate change is determined as the critical power range, and the critical power is determined based on the critical power range.

[0046] The points in the power-response curve are arranged in ascending order of transmit power. Based on the response rates corresponding to adjacent points, the response rate increment and the change in response rate increment are calculated sequentially, and the change in tag response rate with increasing transmit power is determined based on the response rate increment and the change in response rate increment.

[0047] Transmit power from P q-1 Increase to P q The increment in response rate generated at that time is denoted as G. q The response rate increment G q Calculate according to the following formula: G q =C q -C q-1 Among them, C q Indicates the transmit power level P q The corresponding response rate, C q-1 Indicates the transmit power level P q-1 Corresponding response rate; G q The transmit power is represented by P q-1 Increase to P q The increase in label response rate within the preset spatial boundary.

[0048] When the response rate increment is greater than zero, it indicates that the number of response tags in the region has increased after increasing the transmission power; when it is equal to zero, it indicates that the number of response tags in the region has not increased; when it is less than zero, the corresponding curve point is marked as a fluctuation point. For fluctuation points, the response rate is re-acquired according to the number of repeated counts configured in the read task under the same transmission power, and the original response rate of the fluctuation point is replaced with the median of the multiple response rates, and then the response rate increment is recalculated.

[0049] When the power-response curve contains both coarse and fine scan points, the response rate increment is compared only between consecutive points with the same power step size. The first growth rate condition requires at least four points in the consecutive comparison segment, and the second growth rate condition requires at least three points. If the number of points is insufficient, the corresponding condition is not used to determine the critical interval. Adjacent points located at the boundary between the two power step sizes are not included in the continuous change determination.

[0050] Furthermore, the change in response rate increment between adjacent response rate increments is denoted as H. q The change in response rate increment H q Calculate according to the following formula: H q =G q -G q-1 Among them, G q The transmit power is represented by P q-1 Increase to P q The response rate increment at time, G q-1 The transmit power is represented by P q-2 Increase to P q-1 Response rate increment at time; H q Used to represent the change in response rate increment between two adjacent power ranges.

[0051] When H q When H > 0, it indicates that the response rate increment corresponding to the current power range is greater than the response rate increment corresponding to the previous power range, that is, the response rate growth rate of the tag within the preset spatial boundary is increasing; when H q When the value is less than 0, it indicates that the response rate increment corresponding to the current power range is less than the response rate increment corresponding to the previous power range, meaning the response rate growth rate is decreasing. When the change in response rate increment is zero, it indicates that the response rate increment of the current power range is equal to that of the previous power range, meaning the response rate growth rate remains unchanged. When the change in response rate increment changes from a positive value to a non-positive value, it indicates that the power-response rate curve has changed from a state of increasing response rate growth to a state of no longer increasing response rate growth, and the corresponding position is where the label response rate growth trend reverses.

[0052] The preset growth rate condition includes at least one of a first growth rate condition and a second growth rate condition. The first growth rate condition is that the change in response rate increment changes from a positive value to a non-positive value; the second growth rate condition is that the response rate increment changes from being higher than a preset increment threshold to being lower than the preset increment threshold. When either the first growth rate condition or the second growth rate condition is met, it is determined that the change in response rate growth rate within the corresponding power range meets the preset growth rate condition.

[0053] For the first growth rate condition, when H q-1>0 and H q When the value is ≤0, it indicates that the change in responsivity increment changes from positive to non-positive between adjacent power ranges, thus affecting the transmit power level P. q-1 Up to transmit power level P q The power range between these ranges is defined as a critical power interval.

[0054] For the second growth rate condition, the preset incremental threshold is denoted as θ. G The preset incremental threshold θ G Used to represent the minimum increment of the response rate that allows continued growth to be considered effective. When G q-1 >θ G And G q ≤θ G When this occurs, it indicates that the response rate increment has changed from being higher than the preset increment threshold to not being higher than the preset increment threshold, and the transmit power level P is adjusted accordingly. q-1 Up to transmit power level P q The power range between these two values ​​is defined as a critical power interval.

[0055] The preset incremental threshold is determined based on historical valid read tasks. Historical power-response rate curves with preset spatial boundaries, antenna configurations, tag types, and inventory durations that are consistent with the current task are selected. The response rate increments after the confirmed critical power in each historical curve are extracted, and the maximum value of the response rate increment is determined as the preset incremental threshold.

[0056] The historical power-response rate curves used to determine the preset incremental threshold are selected from no fewer than five historical read tasks within 30 days prior to the start time of the current read task. The preset spatial boundaries, antenna configurations, tag types, inventory durations, scanning power ranges, and transmit power step sizes of each historical read task are consistent with those of the current read task, and the tag response data is complete, the area demarcation verification is valid, and no configuration changes occurred during the calibration process.

[0057] When available historical curves are unavailable, the preset incremental threshold is calibrated through trial runs. The response rate increment and the change in response rate increment are calculated sequentially for the trial run curve. The continuous response rate increments after the first change in response rate increment from positive to non-positive are used as calibration samples, and the maximum value of these calibration samples is used to determine the preset incremental threshold. This calibration process is repeated if the tag type, antenna configuration, or preset spatial boundary changes.

[0058] If there are fewer than 5 historical power-response rate curves, perform at least 5 complete trial runs within 24 hours under the same read configuration. Each valid trial run curve should cover the preset scan power range and contain at least two consecutive response rate increments after the position where the response rate increment first changes from positive to negative. If there are fewer than 5 valid trial run curves or the above-mentioned changes do not occur, do not use the second speed-up condition, but use the first speed-up condition or the handling method for the aforementioned missing critical power range to continue calibration.

[0059] It should be noted that the first growth rate condition is used to detect the trend reversal of the response rate increment from increasing to decreasing, while the second growth rate condition is used to detect the state where the response rate increment decreases to within a preset range. The two conditions determine the critical power range from the perspectives of both the trend and magnitude of the increment. When the two conditions yield different critical power ranges, each critical power range is retained and filtered during subsequent critical power determination. When the critical power ranges obtained from the two conditions are the same or overlap, the same or overlapping power range is considered as a single critical power range to avoid the same power range being recorded repeatedly.

[0060] When neither the first nor the second growth rate condition forms a critical power range, the curve point where the response rate is first not lower than the desired coverage rate is found in ascending order of transmit power. If the transmit power corresponding to the curve point is P... q And q is greater than 1, then P q-1 To P q The power range between these two points is defined as the critical power range, and P is... q-1 Determined as critical power P c If q=1, and the power-response curve contains at least two curve points, then the power range between P1 and P2 is defined as the critical power interval, and P1 is defined as the critical power P. c If there are no curve points that meet the desired coverage, or if there are fewer than two available curve points, output the status information that no effective critical power range has been formed, and after adjusting the scanning power range or the transmit power step size, re-execute steps S101 to S103.

[0061] For each critical power range, the lower endpoint of the critical power range is used as a candidate critical power. The lower endpoint represents the transmit power level corresponding to the point where the responsivity increment changes direction or decreases to a preset increment threshold, and is used to characterize the initial power at which the tag responsivity gain in the region begins to weaken due to further increases in transmit power.

[0062] When there is only one critical power interval in the power-response curve, the lower endpoint of the critical power interval is defined as the critical power P. c The critical power Pc As input for step S104.

[0063] When multiple critical power ranges exist in the power-response curve, first compare the response rates corresponding to each candidate critical power and retain the candidate critical power with the highest response rate; if the corresponding response rates are the same, select the candidate critical power with the smallest change in response rate increment; if both values ​​are still the same, select the candidate critical power with the lower transmit power. The screening result is determined as the critical power.

[0064] For example, in the example where the preset total number of tags is 100 as described in step S102, the response rates corresponding to 24dBm, 26dBm, 28dBm, and 30dBm are 0.83, 0.94, 0.96, and 0.96, respectively. The response rate increments corresponding to adjacent power ranges are 0.11, 0.02, and 0, respectively. When the preset increment threshold θ... G When set to a value greater than or equal to 0.02 and less than 0.11, the response rate increment decreases from 0.11 corresponding to the 24dBm to 26dBm power range to 0.02 corresponding to the 26dBm to 28dBm power range, satisfying the second growth rate condition. Therefore, 26dBm to 28dBm is determined as the critical power range, and the lower end of the critical power range, 26dBm, is taken as the candidate critical power.

[0065] In step S104, the target transmit power is determined based on the desired coverage, the critical power, and the preset safety margin, including: Based on the critical power and the preset safety margin, the candidate transmit power range is determined; The desired coverage rate is determined based on the region reading accuracy requirements of the reading task, and the minimum number of response tags is determined based on the desired coverage rate and the preset total number of tags; Based on the power-response rate curve, the lowest transmission power within the preset spatial boundary of the candidate transmission power range, where the number of response tags is not less than the minimum number of response tags, is selected as the target transmission power.

[0066] The preset safety margin is denoted as ΔP. s Used at critical power P c The selectable range of target transmission power is limited based on the critical power P. c and preset safety margin ΔP s Determine the candidate transmit power range I.

[0067] The lower limit of the candidate transmit power range I is the critical power P. c The upper limit of power is denoted as P. h The upper limit of power is determined according to the following formula: P h=min(P c +ΔP s P max ) The candidate transmit power range I is then represented as: I=[P c P h ] Among them, P max This indicates the upper limit of the preset scan power range, used to limit the candidate transmit power range.

[0068] The candidate transmit power range has a lower limit of critical power and an upper limit of the sum of critical power and preset safety margin; when the upper limit exceeds the preset scan power range, the upper limit of the preset scan power range is adopted.

[0069] The preset safety margin can be determined based on the power records of historical reading tasks. For historical reading tasks whose preset spatial boundaries, antenna configurations, and tag types are consistent with the current task, the non-negative difference between the minimum transmit power required to achieve the desired coverage and the corresponding historical critical power is calculated, and the maximum value of the non-negative difference is determined as the preset safety margin.

[0070] The historical readout tasks used to determine the preset safety margin are selected from no fewer than five historical tasks within 30 days prior to the start time of the current readout task. The preset spatial boundaries, antenna configurations, tag types, expected coverage, scanning power range, and transmit power step sizes of each historical readout task are consistent with those of the current readout task, and they have complete power-response curves and valid verification results for area delineation.

[0071] When historical records are lacking, a preset safety margin is calibrated through trial runs: starting from the critical power, the curve points are checked step by step to determine the transmit power at which the number of responding tags first reaches the read mission requirements, and the difference between this transmit power and the critical power is determined as the preset safety margin. This calibration process is repeated if the antenna configuration, tag type, or preset spatial boundary changes.

[0072] When deploying for the first time or when there are fewer than 5 historical read tasks that meet the conditions, the preset safety margin should be determined according to the aforementioned trial operation calibration method. When the critical power P... c The corresponding number of response tags is no less than the minimum number of response tags N. r When, let ΔP s =0; when there are no curve points that meet the conditions within the preset scanning power range, let ΔP s =P max -P c Furthermore, in subsequent target transmission power screening, it outputs status information indicating that the calibration did not meet the area read accuracy requirements. Therefore, the preset safety margin satisfies 0 ≤ ΔP. s ≤Pmax -P c .

[0073] The preset safety margin only limits the width of the candidate transmit power range and is not used as a fixed compensation value directly superimposed to the critical power; the target transmit power is still obtained by screening the actual curve points within the candidate range.

[0074] The desired coverage rate is determined based on the region read accuracy requirements of the read task. This desired coverage rate is denoted as C. e The desired coverage C e The value is greater than 0 and not greater than 1.

[0075] The expected coverage rate represents the minimum percentage of preset tags that must generate a response within the preset spatial boundary for this reading task, relative to the total number of preset tags. It is a task configuration parameter. The upper-level management system configures the expected coverage rate before the reading task begins and maintains its value unchanged during the target transmission power determination and area demarcation verification process.

[0076] In one approach, the region read accuracy requirement for a read task is represented by the maximum permissible missed read rate. Let the maximum permissible missed read rate be denoted as E1, then the expected coverage C... e Determined according to the following formula: C e =1-E1 Where E1 represents the maximum proportion of preset tags that are allowed to not generate a response within the preset space boundary out of the total number of preset tags; C e This represents the expected coverage rate corresponding to the maximum allowable missed read rate. The maximum allowable missed read rate can be pre-configured based on the regional read accuracy requirements of the read task.

[0077] Based on the expected coverage C e Given a preset total number of tags N0, determine the minimum number of response tags. Let N be the minimum number of response tags. r And calculate according to the following formula:

[0078] Where, N r Indicates the minimum number of response tags required to achieve the desired coverage; C e Indicates the expected coverage rate; This indicates a rounding up operation. Using the rounding up method ensures that the actual percentage calculated based on the number of tags is not lower than the desired coverage rate.

[0079] For example, when the preset total number of tags N0 is 100 and the desired coverage C is... e When the value is 0.95, the minimum number of response tags N is... rThe number is 95. When the preset total number of tags N0 is 83 and the expected coverage C is... e When C is 0.95, e ×N0 is 78.85, and the minimum number of response tags N obtained after rounding up is 78.85. r There are 79.

[0080] Select curve points from the power-response curves whose transmit power falls within the candidate transmit power range I, and obtain the number N of response tags within the preset spatial boundary corresponding to each curve point. q The transmit power level that meets the following conditions will be used to achieve the desired coverage: N q ≧N r Since the minimum number of response tags is calculated by converting the expected coverage rate into the total number of preset tags, the response rate at the corresponding curve point satisfies the expected coverage requirement of this reading task when the number of response tags is not less than the minimum number of response tags.

[0081] From the candidate transmit power range I, satisfying N q ≧N r Among the available transmission power levels, the transmission power level with the lowest transmission power value is selected as the target transmission power. This target transmission power is denoted as P. t ,but:

[0082] The curly braces contain a candidate set of target transmit power, and the vertical line indicates that the transmit power levels in the set must simultaneously meet the subsequent limiting conditions. min indicates that the minimum value in the candidate set is selected. When the candidate set is empty, the processing method described below for not meeting the area reading accuracy requirements is executed.

[0083] When the critical power P c The corresponding number of response tags is no less than the minimum number of response tags N. r At that time, the critical power P c The target transmission power P is determined. t When the critical power P c The corresponding number of response tags is less than the minimum number of response tags N. r At that time, check the remaining curve points within the candidate transmission power range in ascending order of transmission power, and select the first one that satisfies N. q ≧N r The transmission power level is determined as the target transmission power P. tIf no curve point that meets the minimum number of response tags is found within the candidate transmit power range, the system outputs a status message indicating that the calibration has not met the area read accuracy requirements, and stops generating the target transmit power. After the upper-level management system verifies the preset tag list, preset spatial boundaries, antenna configuration, and preset safety margin, it restarts the calibration.

[0084] For example, when the critical power P c 26dBm, with a preset safety margin ΔP s When the transmit power is 0.5dB, the candidate transmit power range is 26dBm to 26.5dBm. When the preset total number of tags N0 is 100 and the desired coverage C... e When the value is 0.95, the minimum number of response tags N is... r The number is 95. If the number of response tags corresponding to 26dBm in the power-response rate curve is 94 and the number of response tags corresponding to 26.5dBm is not less than 95, then 26.5dBm is determined as the target transmit power P. t .

[0085] In step S105, tag reading is performed with the target transmission power. Based on the spatial location information corresponding to the tag identifier in the read tag response data, the responding tags are divided into tags within a preset spatial boundary and tags outside a preset spatial boundary. The validity of the area definition is verified based on the division results.

[0086] Before performing the verification read, a unique verification cycle identifier is established for this read, and this verification cycle identifier is associated with and saved along with the target transmission power, response frame, and tag identifier. The RFID reader sets the transmission power to the target transmission power P. t Perform a tag inventory and form the set of response tags for this verification according to the response frame verification and tag identifier deduplication rules specified in step S101.

[0087] Based on the tag identifier of the response tag, the established correspondence between tag identifiers and spatial location information is invoked to obtain the spatial location information corresponding to each response tag. Response tags whose spatial location information falls within a preset spatial boundary are classified as tags within the preset spatial boundary, and those whose spatial location information does not fall within the preset spatial boundary are classified as tags outside the preset spatial boundary. When the spatial location information of a response tag falls within the preset spatial boundary but its tag identifier is not included in the preset tag list, this verification is marked as inconsistent list data, and the area definition determination is paused; after verifying and updating the preset tag list, the verification reading is re-executed. When a response tag does not have corresponding spatial location information, this verification is marked as incomplete location data, and the area definition determination is paused. After supplementing the spatial location information corresponding to the tag identifier, the verification reading is re-executed to avoid including tags with unknown spatial locations in any area. The number of tags within the preset spatial boundary is denoted as N. in The number of labels outside the preset spatial boundary is denoted as N. out N in and N out These correspond to the number of responses within the region and the number of responses outside the region, respectively. Let N be the total number of response tags in this verification. all ,but: N all =N in +N out Where, N all The total number of response tags that complete the spatial location division is used as the denominator for the out-of-bounds misread rate.

[0088] Based on the number N of tags within the preset spatial boundary in The actual coverage rate is determined by the ratio of the actual coverage rate to the preset total number of tags N0, and this actual coverage rate is denoted as C. a Calculate according to the following formula:

[0089] Among them, C a The actual coverage rate C represents the proportion of preset tags that generate a response within a preset spatial boundary when tag reading is performed at the target transmission power. a The value ranges from 0 to 1.

[0090] It should be noted that the actual coverage rate C a The responsivity C in the aforementioned power-responsivity curve is the verification result obtained after performing actual tag reading at the target transmit power. q These are curve data from the power calibration phase. They have different uses and are represented by different symbols.

[0091] Based on the number N of tags outside the preset spatial boundary outTotal number of response tags N all The ratio of the two values ​​is used to determine the out-of-bounds false read rate. This out-of-bounds false read rate is denoted as E0 and calculated using the following formula:

[0092] Where E0 represents the proportion of labels outside the preset spatial boundary to all response labels in this verification, and the outside misread rate E0 ranges from 0 to 1. When N all When C = 0, it indicates that no response tag was read at the target transmission power. In this case, let the actual coverage C... a =0, the division calculation of the misread rate outside the boundary is not performed, and the area delineation is determined to be invalid based on the condition that the actual coverage rate is lower than the expected coverage rate.

[0093] Let the preset misread rate threshold be θ. o The preset misread rate threshold θ o This is used to limit the maximum proportion of tags outside the preset spatial boundary allowed to occupy among all response tags. The preset misread rate threshold is directly configured by the proportion of response tags outside the boundary allowed by the reading task. If a configuration value is missing, during trial operation, verification records where the actual coverage reaches the desired coverage rate are selected, the misread rate outside the boundary for each record is calculated, and the maximum misread rate outside the boundary allowed to be retained by the service is determined as the preset misread rate threshold. This threshold is redefined after changes to the preset spatial boundary or antenna configuration.

[0094] The preset misread rate threshold θ o The value range is from 0 to 1. When the reading accuracy requirement of the reading task specifies the maximum proportion that the outer boundary label is allowed to occupy, this maximum proportion is directly determined as the preset false reading rate threshold. For example, when the allowed proportion is 2%, let θ o =0.02, and remains unchanged during this area delineation verification process. When no allowable ratio is given in the task configuration, under the same preset spatial boundary, antenna configuration, tag type and target transmission power, no less than 5 verification reads are performed within 24 hours, and the maximum value of the out-of-boundary false read rate corresponding to no less than 5 valid verification records is determined as the preset false read rate threshold; if there are less than 5 valid verification records, the conclusion that the area delineation is valid is not output.

[0095] When the actual coverage rate C a No less than the expected coverage rate C e Furthermore, the out-of-bounds misread rate E0 is not higher than the preset misread rate threshold θ. o When the area is defined, the boundary is considered valid, that is:

[0096] Both of the above conditions must be met simultaneously. The actual coverage rate condition is used to determine whether the reading results of the tags within the preset spatial boundary meet the reading task requirements, while the false reading rate condition outside the boundary is used to determine whether the response ratio of the tags outside the preset spatial boundary is within the allowable range.

[0097] For example, when the preset total number of tags N0 is 100 and the desired coverage C is... e When the value is 0.95, tag reading is performed at the target transmission power, resulting in 96 tags within the preset spatial boundary and 1 tag outside the preset spatial boundary. At this point, N... in There are 96, N out For 1, N all There are 97, with an actual coverage rate of C. a The false read rate is 0.96, and the out-of-bounds false read rate E0 is approximately 0.0103. When the preset false read rate threshold θ... o When the value is 0.02, the actual coverage rate is not lower than the expected coverage rate, and the misread rate outside the boundary is not higher than the preset misread rate threshold, thus the area definition is valid.

[0098] When the actual coverage rate C a Below expected coverage C e When the coverage is insufficient, the branch is processed and the transmission power is increased; only when the actual coverage has reached the expected coverage and the false read rate E0 outside the boundary is higher than the preset false read rate threshold θ. o If the error exceeds the limit outside the boundary, the transmission power is reduced. After processing both branches, the next verification cycle begins.

[0099] The power adjustment step size is denoted as... The power adjustment step size is greater than 0 and not greater than the second power step size, in order to reduce the repeated changes in the region definition result between the missed reading state and the misread state caused by excessively large single power adjustment amplitude.

[0100] Let P be the transmit power used in the k-th verification cycle. k In the first verification cycle, the target transmission power determined in step S104 is used, i.e., P1 = P t When the actual coverage rate C a Below expected coverage C e At that time, increase the transmit power for the next verification cycle:

[0101] Among them, P k P represents the transmit power used in the current verification cycle. k+1 This indicates the transmit power used in the next verification cycle. When the actual coverage C... a No less than the expected coverage rate C e Furthermore, the out-of-bounds misread rate E0 is higher than the preset misread rate threshold θ.o At that time, reduce the transmit power for the next verification cycle:

[0102] Through P min and P max Limit the adjusted transmit power to keep the result within the preset scan power range allowed by the RFID reader. (Using the adjusted transmit power P...) k+1 The tag reading is performed again, and the actual coverage and out-of-bounds false read rate are recalculated. When the recalculated actual coverage is not lower than the expected coverage and the recalculated out-of-bounds false read rate is not higher than the preset false read rate threshold, the area demarcation is determined to be valid, and the adjusted transmit power is updated to the target transmit power.

[0103] If the adjusted transmit power reaches the upper limit of the preset scan power range but the actual coverage is still lower than the expected coverage, the output area will be in a state of insufficient tag reading; if the adjusted transmit power reaches the lower limit of the preset scan power range but the false read rate outside the boundary is still higher than the preset false read rate threshold, the output area will be in a state of excessive tag response. Either state will trigger a task configuration check, and the power calibration will be re-executed after the check is completed.

[0104] Multiple adjustments to the target transmit power within a continuous read cycle reflect the cumulative offset of the current read environment relative to the calibration state. To quantify this cumulative offset, the absolute value of the difference in target transmit power between adjacent read cycles is taken and accumulated to obtain the cumulative power adjustment amount:

[0105] Among them, A p This represents the cumulative result of the absolute value of the target transmit power adjustment over multiple consecutive read cycles; K represents the number of read cycles that have been verified; P k P represents the target transmit power used in the k-th readout cycle; k+1 This represents the target transmit power used in the (k-1)th read cycle.

[0106] The absolute value of the adjustment is accumulated so that the adjustment caused by increasing or decreasing the transmission power is included in the cumulative power adjustment, thus avoiding the mutual cancellation of power adjustments in opposite directions.

[0107] Let the preset drift threshold be θ. p Select continuous reading cycles in which the area definition has been continuously valid in history and has not triggered recalibration, calculate the cumulative power adjustment of each cycle segment, and determine the maximum value as the preset drift threshold; if historical records are missing, determine the threshold after forming similar cycle records through trial operation.

[0108] In this embodiment, a continuous reading cycle segment starts from the most recent calibration and adjusts the cumulative power by A. p The verification read cycle begins after zeroing and ends when any of the following occurs: continuous read time reaches 24 hours, the read task ends, the read configuration changes, the region definition verification becomes invalid, or recalibration is triggered. A valid period segment is defined as a period segment containing at least 10 consecutive verification read cycles, where the region definition result in each cycle is valid. At least 5 valid period segments with the same read configuration within 30 days prior to the start time of the current read task are selected, and the maximum cumulative power adjustment value corresponding to each valid period segment is determined as the preset drift threshold. For initial deployments or when the effective period is less than 5, set the initial preset drift threshold θ. p =9 The unit is dB; after forming no less than 5 effective periodic segments, the preset drift threshold is updated according to the maximum value of the cumulative power adjustment.

[0109] If the cumulative power adjustment is not greater than the preset drift threshold, the current calibration result continues to be used; if the cumulative power adjustment exceeds the preset drift threshold, it is determined that the cumulative correction has exceeded the applicable range of the current calibration result, and recalibration is triggered. During recalibration, steps S101 to S104 are executed again to reacquire tag response data at multiple transmit power levels, reconstruct the power-response rate curve, and update the critical power and target transmit power based on the reconstructed power-response rate curve. After recalibration is completed, the cumulative power adjustment A is... p Reset to zero and perform subsequent tag readings using the updated target transmit power.

[0110] In summary, this invention discloses an RFID near-field reading method based on power-response curve calibration. This method can adjust the RFID near-field reading range according to the actual reading environment, taking into account both the reading coverage of tags within the preset spatial boundary and the misreading limitation of tags outside the preset spatial boundary.

[0111] The second embodiment of the present invention provides an RFID near-field area reading system based on power-response curve calibration, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps of the RFID near-field area reading method based on power-response curve calibration described above.

[0112] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A method for reading RFID near-field regions based on power-response curve calibration, characterized in that, include: Obtain a preset spatial boundary and a preset total number of tags within the preset spatial boundary, transmit radio frequency signals at multiple transmission power levels, and receive tag response data; The tag response data shall at least include the tag identifier of the response tag; Based on the tag response data received at each of the aforementioned transmission power levels, a power-response rate curve is constructed; Based on the power-response rate curve, the power range in which the rate of response rate change satisfies the preset rate of increase condition is determined as the critical power range, and the critical power is determined based on the critical power range. The target transmit power is determined based on the desired coverage, the critical power, and the preset safety margin. Tag reading is performed at the target transmission power. Based on the spatial location information corresponding to the tag identifier in the read tag response data, the responding tags are divided into tags within a preset spatial boundary and tags outside a preset spatial boundary. The validity of the area definition is verified based on the division results.

2. The RFID near-field region reading method based on power-response curve calibration according to claim 1, characterized in that, The process of transmitting radio frequency signals at multiple transmission power levels and receiving tag response data includes: Multiple transmit power levels are set sequentially with a first power step, and a preset inventory duration is maintained at each transmit power level to obtain initial tag response data; The power range to be refined is determined based on the initial tag response data. Multiple transmit power levels are set within the power range to be refined with a second power step size smaller than the first power step size, and supplementary tag response data is obtained. The initial tag response data and the supplementary tag response data are integrated to obtain tag response data.

3. The RFID near-field region reading method based on power-response curve calibration according to claim 1, characterized in that, The step of constructing a power-response rate curve based on the tag response data received at each of the aforementioned transmission power levels includes: Based on the spatial location information corresponding to the tag identifier in the tag response data received at each of the aforementioned transmission power levels, determine the number of response tags within the preset spatial boundary at each of the aforementioned transmission power levels; The response rate is determined based on the ratio of the number of response tags to the total number of preset tags, and the power-response rate curve is constructed with the transmission power corresponding to each transmission power level as the horizontal axis and the response rate as the vertical axis.

4. The RFID near-field region reading method based on power-response curve calibration according to claim 3, characterized in that, The step of determining the power range in which the rate of response change satisfies a preset growth condition as the critical power range, and determining the critical power based on the critical power range, includes: Calculate the responsivity increment between adjacent transmit power levels, and the change in responsivity increment between adjacent responsivity increments; When the change in the response rate increment changes from a positive value to a non-positive value, or when the response rate increment changes from being higher than a preset increment threshold to being lower than the preset increment threshold, the corresponding power range is determined as the critical power range. The critical power is determined based on the responsivity and the change in responsivity increment corresponding to each transmit power level within the critical power range.

5. The RFID near-field region reading method based on power-response curve calibration according to claim 1, characterized in that, Determining the target transmit power based on the desired coverage, the critical power, and the preset safety margin includes: Based on the critical power and the preset safety margin, a candidate transmit power range is determined; Based on the power-response rate curve, the transmission power whose response rate satisfies the desired coverage rate is determined from the candidate transmission power range and is taken as the target transmission power; wherein, the desired coverage rate is used to characterize the minimum allowable ratio between the number of response tags within the preset spatial boundary and the total number of preset tags.

6. The RFID near-field region reading method based on power-response curve calibration according to claim 5, characterized in that, The step of determining the transmit power whose responsivity satisfies the desired coverage from the candidate transmit power range based on the power-response curve includes: The desired coverage rate is determined based on the region reading accuracy requirements of the reading task; The minimum number of response tags is determined based on the desired coverage rate and the preset total number of tags; From the candidate transmit power range, the lowest transmit power within the preset spatial boundary with a number of response tags not less than the minimum number of response tags is selected as the target transmit power.

7. The RFID near-field region reading method based on power-response curve calibration according to claim 1, characterized in that, The verification of the validity of the region definition based on the division results includes: The actual coverage rate is determined based on the ratio of the number of tags within the preset spatial boundary to the total number of preset tags in the partitioning results, and the misread rate outside the boundary is determined based on the ratio of the number of tags outside the preset spatial boundary to the total number of response tags in the partitioning results. When the actual coverage rate is not lower than the expected coverage rate and the misread rate outside the boundary is not higher than the preset misread rate threshold, the area definition is determined to be valid.

8. The RFID near-field region reading method based on power-response curve calibration according to claim 7, characterized in that, The step of verifying the validity of the region delineation based on the division results also includes: When the actual coverage is lower than the expected coverage, increase the target transmission power; When the actual coverage is not lower than the expected coverage and the out-of-bounds misread rate is higher than the preset misread rate threshold, the target transmit power is reduced. Perform tag reading with the adjusted target transmit power, and verify the validity of the area delineation based on the tag response data read again.

9. The RFID near-field region reading method based on power-response curve calibration according to claim 8, characterized in that, The step of performing tag reading and verifying the validity of area demarcation using the adjusted target transmit power also includes: The absolute values ​​of each adjustment to the target transmit power within multiple consecutive read cycles are accumulated to obtain the cumulative power adjustment. When the cumulative power adjustment exceeds the preset drift threshold, tag response data is reacquired at multiple transmit power levels, the power-response rate curve is reconstructed, and the critical power and the target transmit power are updated.

10. An RFID near-field area reading system based on power-response curve calibration, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the RFID near-field area reading method based on power-response curve calibration as described in any one of claims 1 to 9.

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