A coding-based RFID interval detection method

Abstract

The present invention discloses a coding-based RFID interval detection method, comprising the following steps: step 1, pre-coding the data in the tag that needs to perform interval detection through a set of coding schemes based on positional value notation; step 2, encoding the current detection interval threshold using the same coding scheme as in step 1, and separating the target tag from the non-target tag using an incremental separation strategy according to the obtained coding vector; the target tag is a tag that meets the interval query condition, and the non-target tag is a tag that does not meet the interval query condition; step 3, counting the target tags separated in step 2, confirming whether the target tag currently exists, and outputting the detection result. The method of the present invention can not only improve the time efficiency of interval detection while ensuring stable performance, but also be compatible with standard RFID tags and directly deployed in commercial RFID systems.

Description

Technical Field

[0001] The invention relates to an RFID interval detection method, in particular to an RFID interval detection method based on coding. Background Art

[0002] Radio Frequency Identification (RFID) is the core technology of the perception layer of the Internet of Things. Compared with traditional perception media, RFID has the distinctive features of small size, low cost, passive perception (no power supply required), non-line-of-sight communication, and batch reading, making it the most widely used technology in the Internet of Things system. With the continuous development of this technology and its in-depth application in various industries, large-scale RFID systems are becoming increasingly popular.

[0003] In this context, efficient RFID information collection methods are crucial. RFID information collection refers to collecting data of interest to users from a collection of tags. These data may be static information of the identified object (such as production batch number, production date), or real-time information of its surrounding environment (such as temperature, humidity). Large-scale RFID systems mean that many RFID tags will compete for limited channel resources at the same time, resulting in increased channel conflicts and a sharp increase in transmission delays, which seriously affects the efficiency of information collection and cannot provide guarantees for the real-time performance of upper-layer applications. The RFID interval detection method is a special information collection method that aims to detect whether there are tags in the current RFID system whose stored data is within a given interval. Interval detection is widely used in all walks of life. Efficient interval detection methods can quickly confirm the existence of target tags (tags that meet the interval query conditions) so that administrators can be warned in time to take corresponding measures in the event of an emergency, thereby avoiding unnecessary property losses and ensuring personnel safety.

[0004] The current solutions for interval detection have the following main problems: 1) Incompatibility with standards - the method has several idealized assumptions that are incompatible with RFID standards; 2) Low time efficiency - in large-scale RFID systems or when the detection interval is large, the time efficiency of the method will be significantly reduced; 3) Poor performance stability - as the detection interval or tag data distribution changes, the time efficiency of the method will fluctuate greatly. Summary of the invention

[0005] Purpose of the invention: The technical problem to be solved by the present invention is to provide an RFID interval detection method based on coding in view of the shortcomings of the prior art.

[0006] In order to solve the above technical problems, the present invention discloses a coding-based RFID interval detection method, comprising the following steps:

[0007] Step 1, pre-encoding the data in the tag that needs to perform interval detection through a set of encoding schemes based on positional value notation;

[0008] Step 2, encode the current detection interval threshold using the same encoding scheme as in step 1, and use an incremental separation strategy to separate the target label and the non-target label according to the obtained encoding vector; the target label is the label that meets the interval query condition, and the non-target label is the label that does not meet the interval query condition;

[0009] Step 3: Take inventory of the target tags separated in step 2, confirm whether the target tags currently exist, and output the detection results.

[0010] The encoding scheme based on the positional value notation described in step 1 of the present invention includes:

[0011] Step 1-1, select a base is a positive integer greater than 1, constructing a digital set

[0012] Step 1-2, for a non-negative integer d, convert it into The number represented by the base number is recorded as

[0013] Steps 1-3, The number on each digit in the The final combination of these vectors is the encoding vector corresponding to the non-negative integer d, denoted as

[0014] The digital set described in step 1-1 of the present invention Among them, the vector v n is a vector in the digital set, and n is

[0015] The incremental separation strategy described in step 2 of the present invention includes:

[0016] Step 2-1, using the threshold value τ of the interval to be detected to obtain a mask set mask_set;

[0017] Step 2-2, construct a Select instruction based on the first mask in the mask set mask_set, activate a maximum target label subset, and silence the remaining target labels and all non-target labels;

[0018] Step 2-3, construct a Select instruction according to the remaining masks in the mask set mask_set, activate a maximum target label subset among the remaining silent target labels in turn, and do not perform any operations on other labels; repeat the above process until all target labels are activated.

[0019] The method for obtaining the mask set in step 2-1 of the present invention includes:

[0020] Step 2-1-1, calculate the values ​​of each variable required to obtain the mask set, including as well as in is the threshold τ in the base The representation in the counting method of for The corresponding encoding vector is, for The rightmost continuous The number of digits, For these continuous The number of consecutive zero digits before a digit, is the encoding vector The index set of character '1' in is the encoding vector The number of characters '1' in the string.

[0021] Step 2-1-2, determine whether the current threshold τ meets the special situation. If Then a length of The zero vector of bits is added to the mask set mask_set, where u is an interval Any positive integer within l RN is the threshold τ in the base Representation in the counting method length and ends step 2-1, i.e. skipping steps 2-1-3 to 2-1-5.

[0022] Step 2-1-3, sequentially transform the mask M(r i ″)+′0′ is added to the mask set mask_set, where M(r″ i ) is the encoding vector corresponding to the threshold τ No. r″ i All characters to the left of the bit but not including the r" i The mask is M(r″ i ) plus the character '0'.

[0023] Step 2-1-4, if Replace the last mask added to the mask set in mask_set with M(r″ i′ ),in And end step 2-1, that is, skip step 2-1-5.

[0024] Step 2-1-5, if M(r″ i′+1 ) is added to the mask set mask_set, where M(r″ i′+1 ) is the encoding vector corresponding to the threshold τ No. r″ i′+1 All characters to the left of the bit but not including the r" i′+1 bits; otherwise, Added mask_set.

[0025] The method of counting the target tags separated in step 2 in step 3 of the present invention includes:

[0026] The Query command in the C1G2 protocol is used to count the target tags. If a reply is received, it indicates that the target tag exists; otherwise, the target tag does not exist; finally, the coding-based RFID interval detection is completed.

[0027] Beneficial effects:

[0028] The present invention proposes a coding-based RFID interval detection method, which, through precoding and tag grouping mechanism, can not only improve the time efficiency of interval detection while ensuring stable performance, but also is compatible with standard RFID tags and can be directly deployed in commercial RFID systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.

[0030] Figure 1 The present invention provides a flowchart of a coding-based RFID interval detection method.

[0031] Figure 2 A flow chart of the encoding scheme based on the positional value notation provided by the present invention.

[0032] Figure 3 This is a flow chart of the incremental separation strategy provided by the present invention.

[0033] Figure 4 The present invention provides a flowchart for obtaining a mask set.

[0034] Figure 5 This is a schematic diagram of the time efficiency comparison experimental results provided by the present invention.

[0035] Figure 6 This is a schematic diagram of the performance stability comparison experiment results provided by the present invention. DETAILED DESCRIPTION

[0036] In order to make the above-mentioned purpose, technical scheme and advantages of the present invention more obvious and easy to understand, the specific implementation of the present invention is described in detail below with reference to the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific implementation disclosed below.

[0037] The present invention discloses a coding-based RFID interval detection method, the method comprising:

[0038] A coding-based RFID interval detection method, such as Figure 1 As shown, the method includes:

[0039] Step S1, pre-encoding the data in the tag that needs to perform interval detection through a set of encoding schemes based on positional value notation;

[0040] Step S2: according to the current detection interval, an incremental separation strategy is used to separate the target tags (tags that meet the interval query conditions) and the non-target tags (tags that do not meet the interval query conditions);

[0041] Step S3: Count the target tags to confirm whether the target tags currently exist and output the detection results.

[0042] Interval detection specifically refers to detecting whether there is a tag whose stored data is within the specified interval. The tag that meets the conditions is called the target tag. If the target tag exists, the detection result is returned as "yes"; if the target tag does not exist, the detection result is returned as "no". Specifically, given a tag set Γ={t1,t2,…,t N}, for a label t in the label set Γ i (1≤i≤N), the data stored is defined as d i To simplify the description, the default value is d i is a positive integer (negative integers or decimals can be mapped to a positive integer interval. The mapping rule is determined by the specific interval detection problem and is not within the scope of this invention). The detection interval can be divided into three categories: [0,τ], [τ,+∞), (τ L ,τ U ]. The interval detection corresponding to these three types of intervals answers the following three questions respectively:

[0043] ·[0,τ] interval detection: set {d i}Is there any data that is not greater than the given lower limit τ?

[0044] ·[τ,+∞) interval detection: set {di}Is there any data that is not less than the given upper limit τ?

[0045] ·(τ L ,τ U ]Interval detection: set {d i} whether there is a value greater than a given lower limit τ L , less than or equal to the given upper limit τ U data?

[0046] The present invention proposes an RFID interval detection method based on coding, the basic idea of ​​which is to separate the target tag from the non-target tag to avoid the non-target tag from participating in the competition for limited channel resources, thereby greatly improving the efficiency of interval detection. This method proposes an encoding scheme based on the positional value system, which significantly reduces the time overhead of the tag separation process by pre-coding the data in the tag.

[0047] The method first executes step S1 to store the data {d i} is encoded, specifically, the data stored in the tag is encoded according to a coding scheme based on the positional value system. i} is converted to

[0048] like Figure 2 As shown, the encoding scheme based on the positional value notation in step S1 includes:

[0049] Step S11: Select a base number c (c is usually a positive integer greater than 1) and construct a digital set.

[0050] Place value counting refers to the method of counting according to the place value system, that is, the size of a number is represented by a set of ordered numbers, and the size represented by each number depends on both its own value and its position. In the following text, "counting method" refers specifically to the place value counting method. In counting method, there is an important concept called cardinality (or weight), which is recorded as This encoding scheme will first select a positive integer As the cardinality, we then construct a bit vector set As a digital set Among them, the vector v i The length is bits, and use the character '0' to initialize each bit of the vector. In order to avoid loss of generality, the index of the vector is specified to increase from right to left, and the rightmost index is 1. Corresponding to the vector v i The i-th character is set to '1', and the other bits remain unchanged (still '0'), that is, The zero vector v0 is not processed.

[0051] Step S12: for a non-negative integer d, convert it into The number represented by the base number is recorded as

[0052] Step S13: The number on each digit in the The corresponding vectors in are replaced, and the final combination of these vectors is the final encoding vector, denoted as

[0053] For example, the selected cardinality You will get a digital set Used to represent the digital numbers 0 to 3, non-negative integers 623 10 In quaternary notation, this would be represented as Each digit of the digit is represented by a digital set By replacing the corresponding vector in , the final encoding vector can be obtained as

[0054] After completing the precoding of the tag data, the next step is to perform step S2 to separate the target tag from the non-target tag. This process mainly utilizes the Select instruction defined in the current global UHF RFID standard - EPCglobal Class1Gen2 (C1G2) protocol. The instruction has a total of 6 fields, which can be simply expressed as follows:

[0055]

[0056] When a tag receives a Select instruction, it will check whether the string starting from the Pointer position and the length of Length bits in the memory block Membank is the same as the mask Mask. If they are the same, the tag is called a matching tag; otherwise, it is called an unmatched tag. Two types of special flags are defined in the tag's memory: inventory flags and selection flags. The Select instruction sets any of these two types of flags based on the mask matching results, the Target field, and the Action field, thereby dividing the tag set into two groups. Both types of flags have two different states (A and B, SL and ~SL). The flag of the matching tag will be set to one of the states, while the flag of the unmatched tag will be set to the other state.

[0057] It is not difficult to know from the basic principle of the above Select instruction that by executing multiple Select instructions, the flag bit of the target tag can be set to one state, and the flag bits of the remaining tags can be set to another state, thereby realizing the logical separation of the target tag and the non-target tag.

[0058] This method designs an incremental separation strategy to reduce the time overhead of the label separation process. The following will first take the [0,τ] interval detection as an example to describe the label separation process in detail; the other two detections, namely the [τ,+∞) interval detection and (τ L ,τ U ] interval detection will be explained later.

[0059] like Figure 3 As shown, the incremental separation strategy in step S2 includes:

[0060] Step S21, obtaining a mask set mask_set using the threshold value τ of the interval to be detected;

[0061] Step S22: construct a Select instruction according to the first mask in the mask set mask_set, activate a maximum target label subset, and silence other labels at the same time;

[0062] Step S23: construct several Select instructions according to the remaining masks in the mask set mask_set, and activate a maximum target tag subset among the remaining silent target tags in turn, while not performing any operation on other tags; repeat this process until all target tags are activated.

[0063] like Figure 4 As shown, the method for obtaining the mask set in step S21 includes:

[0064] Step S211, calculating the values ​​of each variable required to obtain the mask set;

[0065] Step S212: Determine whether the current threshold τ satisfies the special condition. If yes, Then a length of The zero vector of bits is added to the mask set mask_set, and step S21 is ended, i.e., the following steps S213 to S215 are skipped;

[0066] Step S213: For general cases, sequentially convert M(r″ i )+′0′ is added to the mask set mask_set, where

[0067] Step S214: If Replace the last mask added to the mask set mask_set with M(r″i′ ),in And end step S21, that is, skip the next step S215;

[0068] Step S215: If M(r″ i′+1 ) is added to the mask set mask_set; otherwise, Added mask_set.

[0069] To achieve label separation using as few Select instructions as possible, the key is to find the minimum mask set of the data set corresponding to the data held by the target label. The basic idea of ​​the incremental separation strategy is to use the threshold τ to correspond to the encoding vector By using the index of the character '1' in the detection interval, we can find the largest sub-interval that can be matched using only one Select instruction among all the sub-intervals of the detection interval.

[0070] Step S211 first calculates the values ​​of the variables required to obtain the mask set, including as well as The definitions of the variables are given below.

[0071] Given any threshold τ, its cardinality is The counting method can be expressed as:

[0072]

[0073] In the above formula, X1 and X2 are any non-zero numbers, and Y is Corresponding digital, define l RN for The length of , other related definitions are as follows:

[0074] definition is the set of digits where non-zero digits are located, where the digits increase from right to left and the rightmost digit is 0;

[0075] definition For w i The set of numerical values ​​corresponding to the digits on the digits (when the base is not greater than 10, the numbers between 0 and 9 can be used as digits; but when the base is greater than 10, other characters may be used as digits. For example, in the hexadecimal notation, characters A to F are usually used as digits to represent the values ​​10 to 15);

[0076] definition for The rightmost continuous The number of digits;

[0077] definition For these continuous The number of consecutive zero digits preceding a digit.

[0078] In the above formula Corresponding encoding vector for:

[0079]

[0080] definition is the encoding vector The index set of the character '1' in the index set increases from right to left, and the rightmost character index is 0. In order to avoid loss of generality, the indexes in the index set are arranged in descending order of index value, that is, the index satisfies: when i<j, there must be r" i >r″ j .definition is the encoding vector The number of characters '1' in the string.

[0081] For example, when the cardinality is The threshold is τ = 623 10 When And there are:

[0082]

[0083]

[0084]

[0085]

[0086] After obtaining the values ​​of each variable, step S212 determines whether the current threshold is a special case, that is, Where 1≤u<C. If this is the special case, only one mask is needed to match all numbers in the current detection interval [0,τ]. The mask is a length of The zero vector of the bit is added to the mask set mask_set to end step S21; if the current situation is normal, that is, Then continue to execute steps S213 to S215.

[0087] Steps S213 to S215 handle general situations.

[0088] Step S213 will use Center front The index of the character '1' gets i' masks, which are composed of the encoding vector No. r″ iAll characters to the left of the bit but not including the r" i Position (M (r ″ i )) plus '0'. When i = 1, the mask M(r″1)+'0' will match the interval All numbers in; when 1<i≤i′, the mask M(r″ i )+′0′ will match the interval All numbers within.

[0089] far right The characters '1' do not need to be processed one by one, and only one mask is needed to process the remaining unmatched digits. and The design of the last mask is different depending on whether it is 0 or not.

[0090] Step S214 is The final mask construction scheme.

[0091] when and When Ends with A continuous Digital, and these continuous When the number before the digit is not zero, after obtaining i′ masks in step S213, the remaining unmatched data is in the interval Therefore, we only need to remove the last '0' of the i'th mask to match the remaining data, that is, the i'th mask is M(r" i′ ).

[0092] For example, for the sample τ=623 10 , using step S213, three masks can be obtained to match numbers in the interval [0,607]:

[0093] ①[0,511]←mask:00,

[0094] ②[512,575]←mask:010000,

[0095] ③[576,607]←mask:01000100,

[0096] Just delete the '0' at the end of the third mask, and the new mask is as follows:

[0097] ③[576,623]←mask:0100010,

[0098] The above three masks can match all numbers in the interval [0,623].

[0099] when and When The end is neither When the number is not zero, only the number τ remains unmatched. Similarly, just remove the '0' at the end of the last mask in the current mask set to match all the numbers in the interval [0,τ].

[0100] Step S215 is The final mask construction scheme.

[0101] when and When Ends with A continuous Digital, and these continuous When the number before the digit is zero, after obtaining i′ masks, a new mask M(r″) is still required. i′+1 ) to match the interval The data within.

[0102] For example, when the cardinality is The threshold is τ = 591 10 When Using step S213, two masks can be obtained to match numbers in the interval [0,575]:

[0103] ①[0,511]←mask:00,

[0104] ②[512,575]←mask:010000,

[0105] Since z′(4,591 10 )=1>0 and d′(4,591 10 )=2>0, a new mask is needed to process the remaining numbers:

[0106] ③[576,591]←mask:010001000,

[0107] The above three masks can match all numbers in the interval [0,591].

[0108] when and When When the last digit is zero, only the digit τ remains unmatched. A new mask is also needed to match the digit τ alone. The mask is the encoding vector corresponding to the digit τ.

[0109] At this point, step S21 has been completed, and a mask set mask_set that can match all numbers in the interval [0,τ] is obtained. Steps S22 to S23 will use the obtained mask set mask_set to construct a corresponding Select instruction for setting the flag bit of the label.

[0110] Step S22 activates a maximum target tag subset that can be matched using only one Select instruction, while silencing other tags. The Select instruction is constructed as follows:

[0111] Flag←AB:S(t=2,a=0,b=3,p′,l=len1,m=mask1),

[0112] Among them, t=2 means setting the S2 inventory flag; a=0 means that the Action field is AB, that is, the S2 inventory flag of the matching tag is set to A and the unmatched tag is set to B; b=3 means selecting the Membank-3 memory block; l=len1 means that the mask length is the length of the first mask in the mask set; m=mask1 means that the mask is the first mask in the mask set.

[0113] Step S23 constructs several Select instructions based on the remaining masks in the mask set mask_set, and activates a maximum target tag subset in the silent tags in turn, while not performing any operations on other tags; repeat the above process until all target tags are activated. The Select instruction is constructed as follows:

[0114] Flag←A-:S(t=2,a=1,b=3,p′,l=len i ,m=mask i ),

[0115] Where a=1 means that the Action field is A-, that is, the S2 inventory flag of the matching tag is set to A, and no action is performed on the other tags; l=len i Indicates that the mask length is the length of the i-th (i>1) mask in the mask set; m = mask i Indicates that the mask is the i-th mask in the mask set.

[0116] At this point, step S2 has been completed, and all tags (target tags) holding data in the interval [0,τ] have been activated (the inventory flag is set to A); other tags (non-target tags) are silent (the inventory flag is set to B).

[0117] Step S3 will use the Query command defined in the C1G2 protocol to inventory the target tag, confirm whether the target tag currently exists, and output the detection result.

[0118] The Query command is used to start a round of inventory. After using the Select command to set the tag's flag, the next Query command can use the set flag to select which tags to participate in the next inventory. The command can be expressed as follows:

[0119]

[0120] The Sel field determines which tags respond to the command; the Session field selects a count flag; the Target field selects tags with a count flag of A or B to participate in the count, where 0 indicates the tag with a count flag of A is selected and 1 indicates the tag with a count flag of B is selected. When a tag is successfully counted, it will reverse its own count flag (A→B or B→A).

[0121] Step S3 will execute the following Query instruction:

[0122]

[0123] The above instruction will count the tag (target tag) whose S2 inventory flag is A. If a reply is received, it means that the target tag exists; otherwise, the target tag does not exist.

[0124] The above mainly describes the process of performing [0,τ] interval detection in this method. For [τ,+∞) interval detection, it is only necessary to replace the Action field of the Select instruction in step S22 and step S23 from AB and A- to BA and B-. Thus, all tags whose data is not less than the given upper limit τ can be activated (the inventory flag is set to A), while other tags are silenced (the inventory flag is set to B). Then execute step S3 to use the Query instruction to take inventory of the tag (target tag) with the inventory flag A. If a reply is received, it indicates that the target tag exists; otherwise, the target tag does not exist.

[0125] For (τ L ,τ U ] interval detection, you need to first activate the held data in the interval [0,τ U ], and then keep the data silent in the interval [0,τ L Specifically, firstly execute step S1; then use τ U As the threshold, step S2 is executed; then τ L Step S2 is executed again as the threshold, but the Action field of all Select instructions needs to be replaced with B-; finally, step S3 is executed.

[0126] Taking the [0,τ] interval detection as an example, the present invention constructs a typical commercial RFID system containing 500 standard RFID tags, and verifies the performance of the present method in practice through a large number of experiments. The experiment uses an Alien ALR-F800 reader; a directional antenna with a gain of 8.6dBic and an operating frequency of about 920MHz; and 500 common commercial RFID tags (Alien 3412 Higgs3).

[0127] The RQ protocol, the optimal solution for current interval detection, is used as a benchmark to verify the performance of this method in three different scenarios. In scenario 1, the number of tags n is set to 100, and the length of the data in the tag in binary is l bin is 16, the number of target labels n t is 1; in scenario 2, more tags are deployed, that is, n = 500, l bin =16,n t =1; in scenario 3, the data range is expanded, that is, n=500, l bin =32,n t =1. Figure 5 As shown, in all scenarios, the time efficiency of this method is better. Taking scenario 2 as an example, the time overhead of the RQ protocol is 566ms, while that of this method is 336ms, which significantly improves the time efficiency (40.64%).

[0128] In addition to time efficiency, the performance stability of the method is also crucial. Figure 6 The figure shows a box plot based on the experimental results in scenario 3. As shown in the figure, the vertical distance of each method's corresponding box plot represents the discrete degree of its execution time. The longer the distance, the more dispersed the data; the shorter the distance, the more concentrated the data distribution. Obviously, the performance of this method is extremely stable.

[0129] The present invention proposes a coding-based RFID interval detection method, which, through precoding and tag grouping mechanism, can not only improve the time efficiency of interval detection while ensuring stable performance, but also is compatible with standard RFID tags and can be directly deployed in commercial RFID systems.

[0130] In a specific implementation, the present invention further provides a computer storage medium, wherein the computer storage medium can store a program, and when the program is executed, the program can include some or all of the steps in each embodiment provided by the present invention. The storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0131] Those skilled in the art can clearly understand that the technology in the embodiments of the present invention can be implemented by means of software plus a necessary general hardware platform. Based on this understanding, the technical solution in the embodiments of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which can be stored in a storage medium such as ROM / RAM, a disk, an optical disk, etc., and includes a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present invention or some parts of the embodiments.

[0132] The present invention provides a method and idea of ​​a coding-based RFID interval detection method. There are many methods and ways to implement the technical solution. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. A coding-based RFID interval detection method, characterized in that: The following steps are involved: Step 1, pre-encoding the data in the tag that needs to perform interval detection through a set of encoding schemes based on positional value notation; Step 2, encode the current detection interval threshold using the same encoding scheme as in step 1, and use an incremental separation strategy to separate the target label and the non-target label according to the obtained encoding vector; the target label is the label that meets the interval query condition, and the non-target label is the label that does not meet the interval query condition; Step 3: Count the target tags separated in step 2, confirm whether the target tags currently exist, and output the detection results; The encoding scheme based on the positional value notation in step 1 includes: Step 1-1, select a base is a positive integer greater than 1, constructing a digital set Step 1-2, for a non-negative integer d, convert it into The number represented by the base number is recorded as Steps 1-3, The number on each digit in the The final combination of these vectors is the encoding vector corresponding to the non-negative integer d, denoted as The incremental separation strategy described in step 2 includes: Step 2-1, using the threshold value τ of the interval to be detected to obtain a mask set mask_set; Step 2-2, construct a Select instruction based on the first mask in the mask set mask_set, activate a maximum target label subset, and silence the remaining target labels and all non-target labels; Step 2-3, construct a Select instruction according to the remaining masks in the mask set mask_set, activate a maximum target label subset among the remaining silent target labels in turn, and do not perform any operations on other labels; repeat the above process until all target labels are activated; The method of obtaining the mask set in step 2-1 includes: Step 2-1-1, calculate the values ​​of each variable required to obtain the mask set, including as well as in is the threshold τ in the base The representation in the counting method of for The corresponding encoding vector is, for The rightmost continuous The number of digits, For these continuous The number of consecutive zero digits before a digit, is the encoding vector The index set of character '1' in is the encoding vector The number of characters '1' in the string; Step 2-1-2, determine whether the current threshold τ meets the special situation. If Then a length of The zero vector of bits is added to the mask set mask_set, where u is an interval Any positive integer within l RN is the threshold τ in the base Representation in the counting method length, and end step 2-1, i.e. skip steps 2-1-3 to 2-1-5; Step 2-1-3, sequentially transform the mask M(r″) i )+′0′ is added to the mask set mask_set, where M(τ″ i ) is the encoding vector corresponding to the threshold τ No. r″ i All characters to the left of the bit but not including the r" i The mask is M(r″ i ) plus the character '0'; Step 2-1-4, if Replace the last mask added to the mask set in mask_set with M(r″ i′ ),in And end step 2-1, i.e. skip step 2-1-5; Step 2-1-5, if M(r″ i′+1 ) is added to the mask set mask_set, where M(r″ i′+1 ) is the encoding vector corresponding to the threshold τ No. r″ i′+1 All characters to the left of the bit but not including the r" i′+1 bits; otherwise, Added mask_set.

2. The coding-based RFID interval detection method according to claim 1, characterized in that: The digital set described in step 1-1 Among them, the vector is a vector in the digital set, and n is 3. The coding-based RFID interval detection method according to claim 2, characterized in that: The method of counting the target tags separated in step 2 in step 3 includes: The Query command in the C1G2 protocol is used to count the target tags. If a reply is received, it indicates that the target tag exists; otherwise, the target tag does not exist; finally, the coding-based RFID interval detection is completed.

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