A method for information collection in a large-scale multi-tag RFID system based on collision stripping

Abstract

This invention discloses a method for information collection in a large-scale multi-tag RFID system based on collision stripping. This method employs standard Manchester encoding at the physical layer of the multi-tag RFID system. When determining the time slots for tag information transmission, it considers not only single-instance time slots but also the characteristic of multiple tags sharing information on the same object, combined with the decoding characteristics of Manchester encoding. By using information obtained from single-instance time slots, it decodes object information not obtained in the corresponding collision time slots. Compared to existing related protocols that only use single-instance time slots to transmit tag information, this method fully utilizes collision time slots. By understanding the relationships between different types of time slots, it cleverly extracts information from each object, improving time slot utilization and information throughput per unit time.

Description

Technical Field

[0001] This invention relates to the field of radio frequency identification (RFID) technology, and more specifically, to a method for information collection in a large-scale multi-tag RFID system based on collision stripping. Background Technology

[0002] Today, Radio Frequency Identification (RFID) technology plays a crucial role in the Internet of Things (IoT), providing an effective solution for object identification, tracking, and management. Compared to traditional barcodes, RFID technology offers numerous advantages, such as no need for visual identification, high-speed reading and multi-tag identification, long-range identification, large-capacity storage, rewriteability, and dynamic updates. With the rapid development of the global IoT market and the continuous growth of application demands, RFID technology is becoming a focus of attention across various industries. From inventory management in the retail industry to production tracking in smart manufacturing, from medical device management in smart healthcare to cargo tracking in smart logistics, the application of RFID technology is increasingly permeating daily life and work.

[0003] A typical RFID system consists of RFID tags, RFID readers, antennas, and a back-end server, transmitting data and communicating via radio signals. (1) Reader: The reader is the bridge connecting the RFID tags and the back-end server. It is responsible for sending radio signals to nearby RFID tags and receiving the tag's response data, realizing bidirectional data transmission and communication. (2) Tag: A tag in an RFID system is a passive or active device used to store and transmit data to achieve object identification and tracking. Tags are usually composed of a chip and an antenna and can be attached to the surface of an object or embedded inside the object. Each tag has a unique 96-bit ID to identify the object it is bound to. For example, the 96-bit EPC code consists of four fields: an 8-bit header, a 28-bit manufacturer identification code, a 24-bit object classification code, and a 36-bit item serial number. (3) Back-end server: The back-end server is responsible for receiving, processing, and managing the data read from the RFID reader and providing users with rich functions and application interfaces to achieve object identification, tracking, and management. With the continuous development and popularization of RFID technology, the functions and performance of the back-end server are also constantly improving, providing strong support for the development of Internet of Things applications.

[0004] The purpose of information collection protocols is to gather target information from tags in an RFID system. In sensor-enhanced RFID systems, this primarily involves collecting sensor data from tags, such as object state and surrounding environment information. In RFID systems, tags can only communicate with the reader; they cannot communicate with each other. If multiple tags simultaneously send information to the reader, signal collisions can prevent the reader from recognizing each tag's information. To address this problem, there are currently three main solutions: tree-based algorithms, Aloha-based algorithms, and polling-based algorithms. Existing research on collecting target object information often selects a representative tag from multiple tags on an object for information transmission, while other tags do not participate in the information collection process. This requires setting a state (participate or not participate) for each tag and forcibly converting a multi-tag system into a single-tag system, abandoning the multi-tag collaboration benefits of multiple tags sharing the same information on the same object. Furthermore, after selecting a representative tag, previous research only considered singleton time slots when selecting time slots for information transmission, discarding empty and collision time slots, which significantly limits frame throughput. Summary of the Invention

[0005] This invention provides a method for information collection in a large-scale multi-tag RFID system based on collision stripping, which solves the technical problem in the prior art where signal collisions cause the reader to be unable to identify the information of each tag.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0007] This invention provides a method for information collection in a large-scale multi-tag RFID system based on collision stripping, comprising:

[0008] Obtain the IDs of all tags in the multi-tag RFID system and the object information to which they belong. If the object is a target object, all tags under that object are classified as target tags. If the object is not a target object, all tags under that object are classified as non-target tags.

[0009] Using several seeds of a randomly obtained uniform hash function and a uniform hash function, the IDs of all tags are hashed and mapped to several repeatable virtual time slots of a preset bit vector VF.

[0010] Based on the label classification results, the virtual representative time slots of each target object are obtained from several repeatable virtual time slots after mapping;

[0011] Based on the preset bit vector VF and the virtual representative time slot of each target object, an indication vector is constructed;

[0012] Construct the first sequence based on the indicator vector;

[0013] The reader broadcasts the length of the bit vector VF, several seeds, and a uniform hash function to all tags;

[0014] Each tag is hashed according to the aforementioned seeds and a uniform hash function;

[0015] The combined signal, consisting of the results of all tag hash operations and the first sequence, is received by the reader.

[0016] The reader sorts the combined signals according to the reception time and constructs an execution frame EF;

[0017] Based on the virtual representative time slot and execution frame EF of each target object, determine the tag ID and the object information contained in the signal of each time slot in the execution frame EF.

[0018] Furthermore, the length of the preset bit vector VF is f, which is not less than the number of target objects, and each bit of the preset bit vector VF is called a virtual time slot.

[0019] Furthermore, using several seeds of a randomly obtained uniform hash function and the uniform hash function itself, the IDs of all tags are hashed and mapped to several repeatable virtual time slots of a preset bit vector VF, including:

[0020] h i =H(ID) i ,s r )mod f

[0021] In the formula, h i For the i-th tag ID i The mapping result, H(·) is a uniform hash function, s r Let r be the r-th seed, 1≤r≤k, and k different uniform hash functions be simulated by using k different seeds.

[0022] Furthermore, based on the label classification results, virtual representative time slots for each target object are obtained from several repeatable virtual time slots after mapping, including:

[0023] Among the several repeatable virtual time slots after mapping, at least one virtual time slot mapped to a non-target label is marked as the eliminated virtual time slot;

[0024] Then, from the remaining unmarked virtual time slots, randomly select one from the homogeneous virtual time slots mapped to the tag ID corresponding to each target object as the virtual representative time slot of the current target object, while the unselected homogeneous time slots are marked as eliminated virtual time slots; for heterogeneous virtual time slots, if there is one and only one target object that does not have a virtual representative time slot, then mark that virtual time slot as the virtual representative time slot of that target object, and mark the rest as eliminated virtual time slots, until all virtual time slots mapped to tags in the bit vector VF are marked or all target objects have virtual representative time slots;

[0025] The homogeneous virtual time slot is a time slot that includes information about only one object, while the heterogeneous virtual time slot is a time slot that includes information about multiple objects.

[0026] Furthermore, based on the preset bit vector VF and the virtual representative time slots of each target object, an indication vector is constructed, including:

[0027] The length of the indicator vector is equal to the length of the preset bit vector VF. The indicator vector is 1 at the position corresponding to the virtual representative time slot of each target object and 0 at other positions, thus obtaining the indicator vector.

[0028] Furthermore, based on the indicator vector, a first sequence is constructed, including:

[0029] After sorting the position indices corresponding to the virtual representative time slots in the indication vector in ascending order, we get:

[0030] W = {w1, w2, w3, ..., w m}

[0031] In the formula, w1, w2, w3, ..., w m The virtual representative slots are sorted in ascending order, corresponding to their corresponding location indices.

[0032] Let w0 = 0, the first sequence is:

[0033] ΔD={Δd1,Δd2,Δd3,…,Δd m}

[0034] Δd y =w y -w y-1

[0035] In the formula, Δd y Indicates w y and w y-1 The difference.

[0036] Furthermore, based on the results of all tag hash operations and the first sequence, a combined signal is formed and received by the reader:

[0037] Each tag holds a register that is initially set to 0. Each time it receives the value of the incremental sequence broadcast by the reader, it adds the corresponding value to the register and checks whether the value in the register is the same as the previously recorded hash result. If they are equal, the tag information is transmitted to the reader; if they are not equal, it waits for a period of time until the next update.

[0038] The transmitted tag information forms a combined signal that is received by the reader.

[0039] Furthermore, the transmitted tag information forms a combined signal that is received by the reader, including:

[0040] The transmitted tag information is combined into a signal according to Manchester encoding and received by the reader.

[0041] Furthermore, based on the virtual representative time slot of each target object and the execution frame EF, the tag ID and the object information to which each time slot in the execution frame EF belongs are determined, including:

[0042] For homogeneous time slots, the corresponding tag ID and the object information to which it belongs can be obtained directly;

[0043] For heterogeneous time slots, based on the known tag IDs and their associated object information, the unknown tag IDs and their associated object information are obtained sequentially until the object information of all target objects is obtained.

[0044] Furthermore, all the tags also include a flag bit, which is initialized to 1. If the information of the object to which the tag belongs has been received by the reader, it is updated to 0 and no longer participates in the information collection process. The reader will only perform hash calculation on the tag ID with the flag bit set to 1, and only tags with the flag bit set to 1 will respond to the reader's commands.

[0045] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0046] This invention addresses the tag information collection problem in large-scale multi-tag RFID systems and proposes a collision-stripping-based information collection method for such systems. Compared to existing methods, this invention utilizes not only single-instance time slots when specifying tag information transmission time slots, but also leverages the characteristics of Manchester coding to utilize some collision time slots. Since multiple tags on the same object share information, the information obtained from single-instance time slots is used to decode object information not obtained in the corresponding collision time slots. This approach addresses, to some extent, the shortcomings of existing research and improves the utilization rate of time slots and the throughput of information per unit time. Attached Figure Description

[0047] Figure 1A flowchart illustrating an information collection method for a large-scale multi-tag RFID system based on collision stripping, provided in an embodiment of the present invention;

[0048] Figure 2 A schematic diagram of the Manchester encoding principle provided in an embodiment of the present invention;

[0049] Figure 3 A schematic diagram illustrating the principle of determining the tag ID and object information contained in the signal of each time slot, as provided in an embodiment of the present invention.

[0050] Figure 4 A schematic diagram illustrating the selection of a virtual representative time slot as provided in a specific embodiment of the present invention;

[0051] Figure 5 A schematic diagram of a construction execution frame provided for a specific embodiment of the present invention;

[0052] Figure 6 This is a schematic diagram illustrating the extraction of target object information based on collision stripping in a specific embodiment of the present invention;

[0053] Figure 7 This is a schematic diagram showing the performance comparison of various algorithms under different numbers of objects and tag information bits, provided in an embodiment of the present invention. Detailed Implementation

[0054] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this patent.

[0055] To better illustrate this embodiment, some parts in the accompanying drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions;

[0056] It will be understood by those skilled in the art that certain well-known structures and their descriptions may be omitted in the accompanying drawings.

[0057] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0058] Example

[0059] This embodiment provides a method for information collection in a large-scale multi-tag RFID system based on collision stripping, such as... Figure 1 As shown, it includes:

[0060] Obtain the IDs of all tags in the multi-tag RFID system and the object information to which they belong. If the object is a target object, all tags under that object are classified as target tags. If the object is not a target object, all tags under that object are classified as non-target tags.

[0061] Using several seeds of a randomly obtained uniform hash function and a uniform hash function, the IDs of all tags are hashed and mapped to several repeatable virtual time slots of a preset bit vector VF.

[0062] Based on the label classification results, the virtual representative time slots of each target object are obtained from several repeatable virtual time slots after mapping;

[0063] Based on the preset bit vector VF and the virtual representative time slot of each target object, an indication vector is constructed;

[0064] Construct the first sequence based on the indicator vector;

[0065] The reader broadcasts the length of the bit vector VF, several seeds, and a uniform hash function to all tags;

[0066] Each tag is hashed according to the aforementioned seeds and a uniform hash function;

[0067] The combined signal, consisting of the results of all tag hash operations and the first sequence, is received by the reader.

[0068] The reader sorts the combined signals according to the reception time and constructs an execution frame EF;

[0069] Based on the virtual representative time slot and execution frame EF of each target object, determine the tag ID and the object information contained in the signal of each time slot in the execution frame EF.

[0070] In a further embodiment, the length of the preset bit vector VF is f, which is not less than the number of target objects, and each time slot of the preset bit vector VF is called a virtual time slot.

[0071] In this embodiment, the preset bit vector VF is initialized to be completely empty.

[0072] In a further embodiment, using several seeds of a randomly obtained uniform hash function and the uniform hash function, the IDs of all tags are hashed and mapped to several repeatable virtual time slots of a preset bit vector VF, including:

[0073] h i =H(ID) i ,s r )mod f

[0074] In the formula, h i For the i-th tag ID i The mapping result, H(·) is a uniform hash function, s r Let r be the r-th seed, 1≤r≤k, and k different uniform hash functions be simulated by using k different seeds.

[0075] In a further embodiment, based on the label classification results, a virtual representative time slot for each target object is obtained from a plurality of mapped repeatable virtual time slots, including:

[0076] Among the several repeatable virtual time slots after mapping, at least one virtual time slot mapped to a non-target label is marked as the eliminated virtual time slot;

[0077] Then, from the remaining unmarked virtual time slots, randomly select one from the homogeneous virtual time slots mapped to the tag ID corresponding to each target object as the virtual representative time slot of the current target object, while the unselected homogeneous time slots are marked as eliminated virtual time slots; for heterogeneous virtual time slots, if there is one and only one target object that does not have a virtual representative time slot, then mark that virtual time slot as the virtual representative time slot of that target object, and mark the rest as eliminated virtual time slots, until all virtual time slots mapped to tags in the bit vector VF are marked or all target objects have virtual representative time slots;

[0078] The homogeneous virtual time slot is a time slot that includes information about only one object, while the heterogeneous virtual time slot is a time slot that includes information about multiple objects.

[0079] In this embodiment, the virtual representative time slot is used to indicate the actual time slot used to transmit the tag. A time slot involving information about w (w≥2) objects is called a w-heterogeneous time slot. When marking virtual heterogeneous time slots, it starts with 2-heterogeneous virtual time slots. If one target object already has a virtual representative time slot while the other does not, the time slot is marked as the latter's virtual representative time slot. The remaining 2-heterogeneous virtual time slots that do not meet the condition are marked as eliminated virtual time slots. This process continues sequentially, processing 3-heterogeneous virtual time slots, 4-heterogeneous virtual time slots, and so on, until the termination condition is met.

[0080] In a further embodiment, an indication vector is constructed based on the preset bit vector VF and the virtual representative time slots of each target object, including:

[0081] The length of the indicator vector is equal to the length of the preset bit vector VF. The indicator vector is 1 at the position corresponding to the virtual representative time slot of each target object and 0 at other positions, thus obtaining the indicator vector.

[0082] In a further embodiment, a first sequence is constructed based on the indication vector, including:

[0083] After sorting the position indices corresponding to the virtual representative time slots in the indication vector in ascending order, we get:

[0084] W = {w1, w2, w3, ..., w m}

[0085] In the formula, w1, w2, w3, ..., w m The virtual representative slots are sorted in ascending order, corresponding to their corresponding location indices.

[0086] Let w0 = 0, the first sequence is:

[0087] ΔD={Δd1,Δd2,Δd3,…,Δd m}

[0088] Δd y =w y -w y-1

[0089] In the formula, Δd y Indicates w y and w y-1 The difference.

[0090] In a further embodiment, a combined signal is formed by combining the results of all tag hash operations with the first sequence and received by the reader:

[0091] Each tag holds a register that is initially set to 0. Each time it receives the value of the incremental sequence broadcast by the reader, it adds the corresponding value to the register and checks whether the value in the register is the same as the previously recorded hash result. If they are equal, the tag information is transmitted to the reader; if they are not equal, it waits for a period of time until the next update.

[0092] The transmitted tag information forms a combined signal that is received by the reader.

[0093] In a further embodiment, the transmitted tag information constitutes a combined signal that is received by the reader, including:

[0094] The transmitted tag information is combined into a signal according to Manchester encoding and received by the reader.

[0095] In this embodiment, the Manchester encoding principle is as follows: Figure 2 As shown, the main motivation for using Manchester encoding is its ability to decode the last signal when receiving combined signals, given that the other signals in a combined signal are known. Figure 2As shown, in Manchester encoding, "1" and "0" represent high-to-low and low-to-high signal transitions, respectively. Tags A, B, and C store three 7-bit object information bits: "1010000", "1001001", and "1001000". If they respond to the reader in the same time slot using Manchester encoding, the combined signal received by the reader is "10XX00X", where "X" represents a collision bit. Only the different bits in the three tag responses will cause a collision bit in the combined signal; the occurrence of a collision bit is equivalent to the occurrence of a collision bit between the three tag responses. Therefore, if the reader knows any two of the three tags, it can extract the response of the third tag from the combined signal using Manchester encoding.

[0096] In a further embodiment, based on the virtual representative time slot of each target object and the execution frame EF, the tag ID and the object information contained in the signal of each time slot in the execution frame EF are determined, such as... Figure 3 As shown, it includes:

[0097] For homogeneous time slots, the corresponding tag ID and the object information to which it belongs can be obtained directly;

[0098] For heterogeneous time slots, based on the known tag IDs and their associated object information, the unknown tag IDs and their associated object information are obtained sequentially until the object information of all target objects is obtained.

[0099] In specific embodiments, such as Figure 3 As shown, there are five target objects. To collect information about these five objects, time slots 2, 4, 6, 10, and 13 can be selected as representative time slots. Since time slot 4 is a singleton time slot, the reader can directly collect information about object A within this time slot. Based on the characteristics of Manchester encoding, when receiving a combined signal, the combined signal can be decoded using known signals. The reader can further extract information about object B by stripping away the information about object A already obtained in time slot 2. Similarly, information about objects C and D can be extracted sequentially according to the order indicated by the arrows in the diagram.

[0100] In a further embodiment, all the tags also include a flag bit, which is initialized to 1. If the information of the object to which the tag belongs has been received by the reader, it is updated to 0 and no longer participates in the information collection process. The reader will only perform hash calculation on the tag ID with the flag bit set to 1, and only tags with the flag bit set to 1 will respond to the reader's commands.

[0101] Therefore, if the flag bit of all the tags on the target objects is 0, the entire process ends; otherwise, the tags with the flag bit of 1 continue to read information repeatedly.

[0102] This embodiment also provides a specific embodiment to illustrate the method of this embodiment, specifically as follows:

[0103] Please see Figure 4 , Figure 5 , Figure 6 In a specific example, objects A, B, C, D, and F are target objects, while object E is not a target object. Each object has two labels. This implementation will include the following process when collecting target object information:

[0104] Step D1: Set f = 17 to create a bit vector VF of length f. Obtain the IDs of all tags and their associated object information. Based on whether the object is the target object, classify the tags into target tags and non-target tags. Obtain two seeds for the uniform hash function in a random manner.

[0105] Step D2: Using the above seed and uniform hash function H(·), perform a hash operation on each tag ID and map it to two repeatable virtual time slots of VF.

[0106] Step D3: As Figure 4 As shown, for any virtual time slot, if at least one non-target label maps to it, then it is marked as an eliminated virtual time slot, including virtual time slots 10, 12, 15, and 17; while virtual time slots 3, 4, and 11 are unmarked homogeneous time slots. Since virtual time slots 3 and 4 are homogeneous time slots containing only the label of object A, virtual time slot 4 is randomly selected as the virtual representative time slot for object A, so virtual time slot 3 is marked as an eliminated virtual time slot, and virtual time slot 11 is marked as the virtual representative time slot for object D. Virtual time slots 2 and 13 are unmarked 2-heterogeneous virtual time slots. Virtual time slot 2 can be used as the virtual representative time slot for object B, and virtual time slot 13 can be used as the virtual representative time slot for object F. And 3-heterogeneous virtual time slot 6 can be used as the virtual representative time slot for object C, and virtual time slot 10 is eliminated.

[0107] Step D4: The reader constructs the indicator vector IV by setting the values ​​of virtual representative slots 2, 4, 6, 11, and 13 to "1" and all other virtual slots (including the eliminated virtual slots) to "0".

[0108] Step D5: The reader sorts the indices representing the virtual time slots in step D4 (i.e., the indices with a value of "1" in the IV) in ascending order to obtain the index sequence {2, 4, 6, 11, 13}, and then constructs the incremental sequence {2, 2, 2, 5, 2} based on the difference between adjacent indices.

[0109] Step D6: The reader broadcasts parameters such as the IV length f, two seeds, and a uniform hash function, and then broadcasts the values ​​in the incremental sequence sequentially. Meanwhile, as... Figure 5As shown, the tags perform the same hashing process as D2 using the seed and uniform hash function described above, and record the results. Each tag holds a register initially set to 0. Each time it receives the value of the incremental sequence broadcast by the reader, the register is incremented by the corresponding value, and it is checked whether the value in the register is the same as the previously recorded hash result. When the register value is 2, tags 1, 3, and 4 transmit information; when the register value is 4, tag 2 transmits information; when the register value is 6, tags 3, 4, 5, 6, and 7 transmit information; when the register value is 11, tag 7 transmits information; and when the register value is 13, tags 8 and 11 transmit information. The simultaneously transmitted tag information is combined into a signal according to Manchester encoding and received by the reader.

[0110] Step D7: The reader sorts the information from the tag by reception time and constructs the execution frame EF.

[0111] Step D8: As Figure 6 As shown, according to steps D2-D3, the information of each tag and its associated object in each time slot of EF is determined; for example, time slot 1 contains information about objects A and B, and time slot 2 contains information about object A. Since time slots 2 and 4 in EF are singleton time slots, the reader can easily decode their response signals, thereby collecting information about objects A and D. Because the tag response signals in the same time slot are transmitted synchronously using Manchester encoding, the reader can extract information about objects A and D from the response signals recorded in time slots 1, 3, and 5. In this case, time slots 1 and 5 can be considered homogeneous time slots, while time slot 3 can be considered a 2-heterogeneous time slot. Therefore, the reader can extract information about objects B and F from the response signals of time slots 1 and 5. Similarly, by extracting information about object B from the signal recorded in time slot 3, information about object C can also be extracted. Thus, information about all five target objects has been successfully collected.

[0112] Step D9: Update the flag bits of all labels on A, B, C, D, and F to 0. Since the label flag bits of all target objects are 0, this step ends.

[0113] Next, this embodiment will demonstrate a simulation performance comparison between the method of the present invention (hereinafter referred to as the BCP algorithm) and the prior art under different numbers of objects and different numbers of tag information bits:

[0114] By default, the total number of objects is 2. 14 The target objects account for 90% of the total number of objects. Each object has 3 tags, 16 bits of tag information, and 4 seeds.

[0115] like Figure 7As shown in (a), in this implementation case, the execution time increases linearly with the number of objects. BCP performs best, IPP performs similarly to BCP but slightly worse, followed by MIC, and CPP performs the worst.

[0116] like Figure 7 As shown in (b), in this implementation, the execution time of each algorithm increases rapidly as the number of tag information bits increases from 1 to 32. The comparison results are similar to those in 7(a), which are BCP>IPP>MIC>>CPP.

[0117] Overall, this implementation case demonstrates the following conclusions: (1) The number of objects and the number of tag information bits have a linear impact on the execution time of each algorithm; (2) The BCP algorithm outperforms other algorithms in terms of time overhead, showing a significant improvement.

[0118] The same or similar labels correspond to the same or similar parts;

[0119] The terms used to describe positional relationships in the accompanying drawings are for illustrative purposes only and should not be construed as limiting this patent.

[0120] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for information collection in a large-scale multi-tag RFID system based on collision stripping, characterized in that, include: Obtain the IDs of all tags in the multi-tag RFID system and the object information to which they belong. If the object is a target object, all tags under that object are classified as target tags. If the object is not a target object, all tags under that object are classified as non-target tags. Using several seeds of a randomly obtained uniform hash function and a uniform hash function, the IDs of all tags are hashed and mapped to several repeatable virtual time slots of a preset bit vector VF. Based on the label classification results, the virtual representative time slots of each target object are obtained from several repeatable virtual time slots after mapping; Based on the preset bit vector VF and the virtual representative time slot of each target object, an indication vector is constructed; Construct the first sequence based on the indicator vector; The reader broadcasts the length of the bit vector VF, several seeds, and a uniform hash function to all tags; Each tag is hashed according to the aforementioned seeds and a uniform hash function; The combined signal, consisting of the results of all tag hash operations and the first sequence, is received by the reader. The reader sorts the combined signals according to the reception time and constructs an execution frame EF; Based on the virtual representative time slot and execution frame EF of each target object, determine the tag ID and the object information contained in the signal of each time slot in the execution frame EF; The transmitted tag information forms a combined signal that is received by the reader, including: The transmitted tag information is combined into a signal according to Manchester encoding and received by the reader; Based on the virtual representative time slots and execution frames EF of each target object, determine the tag ID and object information contained in the signal of each time slot in the execution frame EF, including: For homogeneous time slots, the corresponding tag ID and the object information to which it belongs can be obtained directly; For heterogeneous time slots, based on the known tag IDs and their associated object information, the unknown tag IDs and their associated object information are obtained sequentially until the object information of all target objects is obtained.

2. The method for information collection in a large-scale multi-tag RFID system based on collision stripping according to claim 1, characterized in that, The preset bit vector VF has a length of f, which is not less than the number of target objects. Each bit of the preset bit vector VF is called a virtual time slot.

3. The method for information collection in a large-scale multi-tag RFID system based on collision stripping according to claim 2, characterized in that, Using several randomly obtained seeds of a uniform hash function and the uniform hash function itself, the IDs of all tags are hashed and mapped to several repeatable virtual time slots of a preset bit vector VF, including: h i =H(ID i ,s r )mod f In the formula, h i For the i-th tag ID i The mapping result, H() is a uniform hash function, s r Let r be the r-th seed, 1≤r≤k, and k different uniform hash functions be simulated by using k different seeds.

4. The method for information collection in a large-scale multi-tag RFID system based on collision stripping according to claim 2, characterized in that, Based on the label classification results, virtual representative time slots for each target object are obtained from several repeatable virtual time slots after mapping, including: Among the several repeatable virtual time slots after mapping, at least one virtual time slot mapped to a non-target label is marked as the eliminated virtual time slot; Then, from the remaining unmarked virtual time slots, randomly select one from the homogeneous time slots mapped to the tag ID corresponding to each target object as the virtual representative time slot of the current target object, while the unselected homogeneous time slots are marked as eliminated virtual time slots; for heterogeneous time slots, if there is one and only one target object that does not have a virtual representative time slot, then mark that virtual time slot as the virtual representative time slot of that target object, and mark the rest as eliminated virtual time slots, until all virtual time slots mapped to tags in the bit vector VF are marked or all target objects have virtual representative time slots; The homogeneous time slot is a virtual time slot that includes only one object's information, while the heterogeneous time slot is a virtual time slot that includes information about multiple objects.

5. The method for information collection in a large-scale multi-tag RFID system based on collision stripping according to claim 4, characterized in that, Based on the preset bit vector VF and the virtual representative time slots of each target object, an indication vector is constructed, including: The length of the indicator vector is equal to the length of the preset bit vector VF. The indicator vector is 1 at the position corresponding to the virtual representative time slot of each target object and 0 at other positions, thus obtaining the indicator vector.

6. The method for information collection in a large-scale multi-tag RFID system based on collision stripping according to claim 5, characterized in that, Based on the indicator vector, construct the first sequence, including: After sorting the position indices corresponding to the virtual representative time slots in the indication vector in ascending order, we get: W={w1,w2,w3,…,w m } In the formula, w1, w2, w3, ..., w m The virtual representation slots are arranged in ascending order, and m represents the number of "1"s in the indicator vector, where 1 ≤ m ≤ f. Let w0 = 0, the first sequence is: ΔD={Δd1,Δd2,Δd3,…,Δd m } Δd y =in y -In y-1 In the formula, Δd y Indicates w y and w y-1 The difference is 1≤y≤m.

7. The method for information collection in a large-scale multi-tag RFID system based on collision stripping according to claim 6, characterized in that, The combined signal, consisting of the results of all tag hash operations and the first sequence, is received by the reader: Each tag holds a register that is initially set to 0. Each time it receives the value of the incremental sequence broadcast by the reader, it adds the corresponding value to the register and checks whether the value in the register is the same as the previously recorded hash result. If they are equal, the tag information is transmitted to the reader; if they are not equal, it waits for a period of time until the next update. The transmitted tag information forms a combined signal that is received by the reader.

8. The method for information collection in a large-scale multi-tag RFID system based on collision stripping according to any one of claims 1 to 7, characterized in that, All tags also include a flag bit, which is initialized to 1. If the information of the object to which the tag belongs has been received by the reader, it is updated to 0 and no longer participates in the information collection process. The reader will only perform hash calculation on the tag ID with the flag bit set to 1, and only tags with the flag bit set to 1 will respond to the reader's commands.

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