Spectrum shift based backscattering multi-user non-harmonic interference access method and system

Abstract

The application provides a spectrum shift-based backscattering multi-user non-harmonic interference access method and system, belongs to the technical field of radio frequency identification, configures differentiated parameters for various communication devices, makes the main lobe of each channel signal distributed in different frequency bands, and determines the frequency spectrum coverage range after signal frequency shift; according to the channel conflict relationship between devices, a non-directional graph model is constructed; according to the non-directional graph model, a channel allocation optimization model is established with the constraint condition of avoiding interference between users and the target of maximizing the number of available channels of the system; the channel allocation optimization model is solved to obtain an optimal channel allocation scheme. The application realizes effective avoidance of signal harmonic interference in the frequency shift process by reasonably configuring device-related parameters, thereby guaranteeing the reliability of multi-user parallel transmission; the method does not need to modify hardware facilities and is easy to implement in practice, and provides an efficient and reliable solution for the multi-user access problem in the radio frequency identification system and the environmental Internet of Things scene.

Description

Technical Field

[0001] This invention relates to the field of radio frequency identification technology, and specifically to a method and system for multi-user harmonic interference-free access based on spectrum shifting and backscattering. Background Technology

[0002] A key technical feature of RFID systems and the Internet of Things (IoT) in the environment (also known as passive IoT) is the support for a large number of users accessing the network. A critical challenge in achieving parallel access for multiple users based on backscatter communication technology is that a large number of sensors need to share the channel, and signal collisions occur when multiple tags transmit in parallel within the same frequency band. Traditional RFID systems using time-slotted ALOHA protocols or binary tree-based deterministic access methods suffer from low efficiency and limited capacity, making it difficult to meet the needs of parallel access for multiple users. To address this issue, frequency shifting technology can be used to achieve frequency division multiplexing. However, in frequency shifting schemes, adding RF devices to achieve frequency shifting leads to increased power consumption and cost, making large-scale applications difficult. Therefore, using square waves to approximate the carrier signal for frequency shifting to achieve multi-user access becomes a potentially feasible solution. Summary of the Invention

[0003] The purpose of this invention is to provide a backscattering multi-user harmonic interference-free access method and system based on spectrum shifting, so as to solve at least one of the technical problems existing in the background art.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] In a first aspect, the present invention provides a backscattering multi-user harmonic interference-free access method based on spectrum shifting, comprising the following steps:

[0006] Configure differentiated parameters for each communication device so that the main lobe of each channel signal is distributed in different frequency bands, and determine the spectrum coverage range after the signal frequency shift;

[0007] Based on the channel conflict relationships between devices, an undirected graph model is constructed;

[0008] Based on the undirected graph model, with the constraint of avoiding interference between users and the objective of maximizing the number of available channels in the system, a channel allocation optimization model is established.

[0009] Solve the channel allocation optimization model to obtain the optimal channel allocation scheme.

[0010] As a further limitation of the first aspect of the present invention, configuring differentiated parameters for each communication device includes the following key transmission parameter combinations: data rate r b Backscatter link frequency f i For user i, the bandwidth range [L] to be allocated to it i Ui ], where the left endpoint L i =f i -r b The right endpoint U i =f i +r b Avoiding the bandwidth range occupied by user i' [L i' U i' ], i≠i', where the left endpoint L i' =f i' ×h i' -r b The right endpoint U i' =f i' ×h i' +r b , Let M represent the set of odd harmonic orders; M = {2, 4, ..., 2N}, |M| = N, where N represents the cardinality of the set, corresponding to N frequency-shifted channels; m represents the number of subcarrier cycles. i ∈M uniquely identifies an independent communication channel and satisfies The constraint relationship, where

[0011] As a further limitation of the first aspect of the present invention, an undirected graph model is constructed based on the channel conflict relationship between devices, including: constructing an undirected graph G = (V, E), where the vertex set V corresponds to the subcarrier cycle number set M, i.e., V = {m i |m i ∈M}; Traversing the set of harmonic orders Each harmonic pair combination (h) i ,h i' ), where h i , Calculate m i In h i Bandwidth range of first harmonics and m i' In h i' Bandwidth range of first harmonics If the judgment interval and There is an intersection, that is, it satisfies Then add a connection vertex m in graph G. i and m i' undirected edge (m) i ,m i' ), that is, E←E∪{(m i ,m i' Undirected graph models do not have self-loop edges, that is, for any m i ∈V, the edge set E does not contain the element (m i ,mi' ).

[0012] As a further limitation of the first aspect of the present invention, a channel allocation optimization model is constructed, comprising:

[0013]

[0014] Where S is the set of channel allocation schemes to be solved, the optimization objective |S| represents the cardinality of the selected channel set, |S|<|M|=N; the constraints ensure that any two vertices s in the set S are equal. k ,s k' There is no edge between (s) k ,s k' ( ) connection, meaning there is no interference between corresponding users.

[0015] As a further limitation of the first aspect of the present invention, solving the channel allocation optimization model to obtain the optimal channel allocation scheme includes: initializing the maximum vertex subset I, i.e. Perform connectivity analysis on an undirected acyclic graph G to identify connected subgraphs {G'}. l =(V' l ,E' l )}, l≤L max L max Represents the number of connected subgraphs; traverse the vertex set V, filter out all isolated vertices and form an isolated vertex set. For a connected subgraph G' l , l≤L max Solve for its vertex subset satisfy: The vertex subsets {I' of each connected subgraph i Merge the set of isolated vertices with the set of isolated vertices W to generate the largest subset of vertices: I = (U i I' l )∪W, where Global optimal solution S opt =I, its cardinality |S opt The maximum number of users that can be supported without interference is |I|, where i is the user and i ≤ |S|. opt |Configure relevant parameters m i , where m i ∈S opt Maintain the data rate r of each user b Consistent, calculate the corresponding center frequency f i Allocate bandwidth resources [L] i U i ], where the left endpoint L i =f i -r bThe right endpoint U i =f i +r b , guarantee |S opt Disruption-free transmission for a number of users.

[0016] As a further limitation of the first aspect of the present invention, the method for solving the vertex subset of a connected subgraph is as follows:

[0017] (a) Initialize the three sets X.

[0018] (b) Check the termination condition: If but It is a subset of vertices that satisfy the constraints, output Record If the solution is a candidate, proceed to step (g); otherwise, continue to step (c).

[0019] (c) From Choose any vertex v in the array and add v to the array. Update collection X, X new =X∩fν). fν) represents a vertex in the corresponding set that is not adjacent to v;

[0020] (d) Use the updated set ( X←X new Repeat step (a);

[0021] (e) After processing v at the current recursive level, from Remove v from the middle: Add v to X: X = X ∪ {ν};

[0022] (f) Return to step (b) and process. The remaining vertices;

[0023] (g) All vertex subsets obtained by filtering satisfy the conditions of maximizing the cardinality of the set and minimizing the sum of its elements, i.e. Output I' i .

[0024] Secondly, the present invention provides a backscattering multi-user harmonic-free access system based on spectrum shifting, comprising the following steps:

[0025] The configuration module is used to configure differentiated parameters for each communication device, so that the main lobe of each channel signal is distributed in different frequency bands, and to determine the spectrum coverage range after the signal frequency shift.

[0026] The first construction module is used to construct an undirected graph model based on the channel conflict relationship between devices;

[0027] The second construction module is used to establish a channel allocation optimization model based on the undirected graph model, with the constraint of avoiding interference between users and the objective of maximizing the number of available channels in the system.

[0028] The solution module is used to solve the channel allocation optimization model to obtain the optimal channel allocation scheme.

[0029] Thirdly, the present invention provides a non-transitory computer-readable storage medium for storing computer instructions, which, when executed by a processor, implement the backscattering multi-user harmonic-free access method based on spectrum shifting as described in the first aspect.

[0030] Fourthly, the present invention provides a computer device including a memory and a processor, wherein the processor and the memory communicate with each other, the memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the backscattering multi-user harmonic interference-free access method based on spectrum shifting as described in the first aspect.

[0031] Fifthly, the present invention provides an electronic device, comprising: a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory to cause the electronic device to execute instructions for implementing the backscattering multi-user harmonic interference-free access method based on spectrum shifting as described in the first aspect.

[0032] The beneficial effects of this invention are: by rationally configuring relevant equipment parameters, effective avoidance of signal harmonic interference is achieved during frequency shifting, thereby ensuring the reliability of multi-user parallel transmission. This method requires no hardware modification, is easy to implement in practice, and provides an efficient and reliable solution to multi-user access problems in RFID systems and environmental IoT scenarios.

[0033] The advantages of additional aspects of the invention will be set forth more clearly in the following description or will be learned by practice of the invention. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1This is a flowchart illustrating the workflow of the backscattering multi-user harmonic interference-free access method based on spectrum shifting as described in an embodiment of the present invention.

[0036] Figure 2 This is a flowchart illustrating the vertex subset solution process for the backscattering multi-user harmonic-free access method based on spectrum shifting, as described in an embodiment of the present invention.

[0037] Figure 3 This is a frequency domain resource map after frequency shifting for the backscattering multi-user harmonic interference-free access method based on spectrum shifting described in this embodiment of the invention.

[0038] Figure 4 This is a schematic diagram of an undirected graph model of the backscattering multi-user harmonic interference-free access method based on spectrum shifting described in an embodiment of the present invention. Detailed Implementation

[0039] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0040] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0041] It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as here.

[0042] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, and / or groups thereof.

[0043] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0044] To facilitate understanding of the present invention, the present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments. However, the specific embodiments do not constitute a limitation on the embodiments of the present invention.

[0045] Those skilled in the art should understand that the accompanying drawings are merely schematic diagrams of embodiments, and the components in the drawings are not necessarily essential for implementing the present invention.

[0046] This invention primarily addresses the harmonic interference problem inherent in the frequency shifting process of square wave signals. A harmonic-free multi-user access method based on spectrum shifting and backscattering effectively solves the co-channel interference problem during parallel transmission of multiple devices in RFID systems and environmental IoT scenarios. It effectively avoids harmonic interference during frequency shifting, thus ensuring the reliability of multi-user parallel transmission. This method requires no hardware modification, is easy to implement in practice, and provides an efficient and reliable solution for multi-user access in RFID systems and environmental IoT scenarios.

[0047] In this method, using a square wave to approximate the carrier signal for frequency shifting to achieve multi-user access is a potentially feasible solution.

[0048] The specific principle is as follows: the original signal x(t) is passed through an approximate carrier signal s. m After modulation (t), the modulated signal y(t) is obtained. The approximate carrier wave has a period of... The time-domain expression of a square wave can be written as:

[0049]

[0050] Therefore, the modulated signal can be expressed as:

[0051]

[0052] Because square wave signals have harmonics, as can be seen from the formula, periodic square waves have harmonics at odd multiples of f. b There are frequency components in certain areas, so the modulated device signal will contain harmonics.

[0053]

[0054] Example 1

[0055] In this embodiment 1, a backscattering multi-user harmonic interference-free access system based on spectrum shifting is first provided, including: a configuration module, used to configure differentiated parameters for each communication device so that the main lobe of each channel signal is distributed in different frequency bands, and to determine the spectrum coverage range after the signal frequency shift; a first construction module, used to construct an undirected graph model according to the channel conflict relationship between devices; a second construction module, used to establish a channel allocation optimization model based on the undirected graph model, with the constraint of avoiding interference between users and the objective of maximizing the number of available channels in the system; and a solution module, used to solve the channel allocation optimization model to obtain the optimal channel allocation scheme.

[0056] In this embodiment, the above-described system is used to implement a backscattering multi-user harmonic interference-free access method based on spectrum shifting, including the following steps:

[0057] Configure differentiated parameters for each communication device so that the main lobe of each channel signal is distributed in different frequency bands, and determine the spectrum coverage range after the signal frequency shift;

[0058] Based on the channel conflict relationships between devices, an undirected graph model is constructed;

[0059] Based on the undirected graph model, with the constraint of avoiding interference between users and the objective of maximizing the number of available channels in the system, a channel allocation optimization model is established.

[0060] Solve the channel allocation optimization model to obtain the optimal channel allocation scheme.

[0061] The differentiated parameters configured for each communication device include the following key transmission parameter combinations: data rate r b Backscatter link frequency f i For user i, the bandwidth range [L] to be allocated to it i U i ], where the left endpoint L i =f i -r b The right endpoint U i =f i +r b Avoiding the bandwidth range occupied by user i' [L i' U i' ], i≠i', where the left endpoint L i' =f i' ×h i' -r b The right endpoint U i' =f i' ×h i' +rb , Let M represent the set of odd harmonic orders; M = {2, 4, ..., 2N}, |M| = N, where N represents the cardinality of the set, corresponding to N frequency-shifted channels; m represents the number of subcarrier cycles. i ∈M uniquely identifies an independent communication channel and satisfies The constraint relationship, where

[0062] Based on the channel conflict relationships between devices, an undirected graph model is constructed, including: constructing an undirected graph G = (V, E), where the vertex set V corresponds to the subcarrier cycle number set M, i.e., V = {m}. i |m i ∈M}; Traversing the set of harmonic orders Each harmonic pair combination (h) i ,h i' ), where h i , i≠i';Calculate m i In h i Bandwidth range of first harmonics and m i' In h i' Bandwidth range of first harmonics If the judgment interval and There is an intersection, that is, it satisfies Then add a connection vertex m in graph G. i and m i' undirected edge (m) i ,m i' ), that is, E←E∪{(m i ,m i' Undirected graph models do not have self-loop edges, that is, for any m i ∈V, the edge set E does not contain the element (m i ,m i' ).

[0063] Construct a channel allocation optimization model, including:

[0064]

[0065] Where S is the set of channel allocation schemes to be solved, the optimization objective |S| represents the cardinality of the selected channel set, |S|<|M|=N; the constraints ensure that any two vertices s in the set S are equal. k ,s k' There is no edge between (s) k ,s k' ( ) connection, meaning there is no interference between corresponding users.

[0066] Solving the channel allocation optimization model to obtain the optimal channel allocation scheme includes: initializing the maximum vertex subset I, i.e. Perform connectivity analysis on an undirected acyclic graph G to identify connected subgraphs G' l =(V' l ,E' l )}, l≤L max L max Represents the number of connected subgraphs; traverse the vertex set V, filter out all isolated vertices and form an isolated vertex set. For a connected subgraph G' l , l≤L max Solve for its vertex subset satisfy: The vertex subsets {I' of each connected subgraph i Merge the set of isolated vertices with the set of isolated vertices W to generate the largest subset of vertices: I = (U i I' l )∪W, where Global optimal solution S opt =I, its cardinality |S opt The maximum number of users that can be supported without interference is |I|, where i is the user and i ≤ |S|. opt |Configure relevant parameters m i , where m i ∈S opt Maintain the data rate r of each user b Consistent, calculate the corresponding center frequency f i Allocate bandwidth resources [L] i U i ], where the left endpoint L i =f i -r b The right endpoint U i =f i +r b , guarantee |S opt Disruption-free transmission for a number of users.

[0067] The method for finding the vertex subset of a connected subgraph is as follows:

[0068] (a) Initialize the three sets X.

[0069] (b) Check the termination condition: If but It is a subset of vertices that satisfy the constraints, output Record If the solution is a candidate, proceed to step (g); otherwise, continue to step (c).

[0070] (c) From Choose any vertex v in the array and add v to the array. Update collection X, X new =X∩fν). fν) represents a vertex in the corresponding set that is not adjacent to v;

[0071] (d) Use the updated set ( X←X new Repeat step (a);

[0072] (e) After processing v at the current recursive level, from Remove v from the middle: Add v to X: X = X ∪ {ν};

[0073] (f) Return to step (b) and process. The remaining vertices;

[0074] (g) All vertex subsets obtained by filtering satisfy the conditions of maximizing the cardinality of the set and minimizing the sum of its elements, i.e. Output I' i .

[0075] like Figure 1 The diagram shows a process flow for a backscattering multi-user harmonic-free access method based on spectrum shifting, which includes the following steps:

[0076] Configure differentiated parameters for each communication device so that the main lobe of each channel signal is distributed in different frequency bands, and determine the spectrum coverage range after the signal frequency shift;

[0077] Based on the channel conflict relationships between devices, an undirected graph model is constructed;

[0078] Based on the undirected graph model, with the constraint of avoiding interference between users and the objective of maximizing the number of available channels in the system, a channel allocation optimization model is established.

[0079] Solve the optimization model to obtain the optimal channel allocation scheme.

[0080] like Figure 2 The diagram shows a flowchart of vertex subset solving for a backscattering multi-user harmonic-free access method based on spectrum shifting, which includes the following steps:

[0081] (a) Initialize the three sets X. (b) Check the termination condition: If but It is a subset of vertices that satisfy the constraints, output Record If the solution is a candidate, proceed to step (g); otherwise, continue to step (c); (c) from Choose any vertex v in the array and add v to the array. Update collection X, X new =X∩f(ν). f(ν) represents the vertices in the corresponding set that are not adjacent to v. Execute step (d); (d) use the updated set ( X←X new Repeat step (a); (e) after processing v at the current recursive level, from Remove v from the middle: Add v to X: X = X ∪ {ν}; (f) Return to step (b) and process. (g) Select all subsets of vertices that satisfy the conditions of maximizing the cardinality of the set and minimizing the sum of its elements. Output I' i .

[0082] In this embodiment, considering multi-device parallel transmission using Miller encoding, the data rate r b =5kbps, the relocation plan is determined to maintain the data rate r b Consistent, the number of subcarrier cycles m is adjusted according to the frequency of the frequency shift. i m i The values ​​are even integers, and the backscatter link frequencies f and m are... i Adjust together, m i The maximum value is fixed at 12, and the corresponding set of subcarrier cycle numbers M = {2, 4, 6, 8, 10, 12}. Based on this scheme, determine the optimal set S of the subcarrier cycle number set M. opt This avoids inter-signal harmonic interference while maximizing the number of parallel transmissions.

[0083] At a given data rate r b The number of different subcarrier cycles m i Table 1 provides the corresponding bandwidth range for each value. Figure 3 As shown. Based on the constructed frequency domain resource graph, an undirected graph is constructed as follows. Figure 4 As shown, this undirected graph contains two connected subgraphs and one isolated vertex. The optimal set {2,4,8} can be obtained by combining the subset of vertices obtained from the connected subgraphs and the isolated vertex.

[0084] Given data rate r b=5kbps, with harmonic interference orders set to 3rd and 5th, and the cardinality N of the subcarrier cycle number set M not fixed, the optimal solutions for the corresponding sets are given in Table 2. When N is 32, the corresponding optimal set {2,12,14,16,18,20,22,24,26,28,30,32} is achieved, realizing parallel transmission for 12 users and effectively avoiding high-order harmonic interference.

[0085] In summary, the backscattering multi-user harmonic interference-free access method based on spectrum shifting proposed in this embodiment configures different parameters for different devices, achieving frequency shifting while effectively avoiding inter-signal harmonic interference and ensuring the reliability of multi-user parallel transmission. It effectively avoids co-channel interference problems during parallel transmission between devices, requires no hardware modification, and is easy to implement in practice.

[0086] Table 1

[0087] <![CDATA[r b =5kpbs]]> f Occupied bandwidth kHz (1st, 3rd, 5th order) <![CDATA[m1=2]]> 10k 5～15，25～35，45～55 <![CDATA[m2=4]]> 20k 15～25，55～65，95～105 <![CDATA[m3=6]]> 30k 25～35，85～95，145～155 <![CDATA[m4=8]]> 40k 35～45，115～125，195～205 <![CDATA[m5=10]]> 50k 45～55，145～155，245～255 <![CDATA[m6=12]]> 60k 55～65，175～185，295～305

[0088] Table 2

[0089]

[0090] Example 2

[0091] This embodiment 2 provides a non-transitory computer-readable storage medium for storing computer instructions. When executed by a processor, the computer instructions implement the backscattering multi-user harmonic-free access method based on spectrum shifting as described above. The method includes:

[0092] Configure differentiated parameters for each communication device so that the main lobe of each channel signal is distributed in different frequency bands, and determine the spectrum coverage range after the signal frequency shift;

[0093] Based on the channel conflict relationships between devices, an undirected graph model is constructed;

[0094] Based on the undirected graph model, with the constraint of avoiding interference between users and the objective of maximizing the number of available channels in the system, a channel allocation optimization model is established.

[0095] Solve the channel allocation optimization model to obtain the optimal channel allocation scheme.

[0096] Example 3

[0097] This embodiment 3 provides a computer device, including a memory and a processor, wherein the processor and the memory communicate with each other, and the memory stores program instructions that can be executed by the processor. The processor calls the program instructions to execute the backscattering multi-user harmonic interference-free access method based on spectrum shifting as described above, the method including:

[0098] Configure differentiated parameters for each communication device so that the main lobe of each channel signal is distributed in different frequency bands, and determine the spectrum coverage range after the signal frequency shift;

[0099] Based on the channel conflict relationships between devices, an undirected graph model is constructed;

[0100] Based on the undirected graph model, with the constraint of avoiding interference between users and the objective of maximizing the number of available channels in the system, a channel allocation optimization model is established.

[0101] Solve the channel allocation optimization model to obtain the optimal channel allocation scheme.

[0102] Example 4

[0103] This embodiment 4 provides an electronic device, including: a processor, a memory, and a computer program; wherein, the processor is connected to the memory, and the computer program is stored in the memory. When the electronic device is running, the processor executes the computer program stored in the memory to cause the electronic device to execute instructions to implement the backscattering multi-user harmonic interference-free access method based on spectrum shifting as described above. The method includes:

[0104] Configure differentiated parameters for each communication device so that the main lobe of each channel signal is distributed in different frequency bands, and determine the spectrum coverage range after the signal frequency shift;

[0105] Based on the channel conflict relationships between devices, an undirected graph model is constructed;

[0106] Based on the undirected graph model, with the constraint of avoiding interference between users and the objective of maximizing the number of available channels in the system, a channel allocation optimization model is established.

[0107] Solve the channel allocation optimization model to obtain the optimal channel allocation scheme.

[0108] In summary, the present invention provides a backscatter-based multi-user harmonic interference-free access method based on spectrum shifting. This method includes: configuring differentiated parameters for each communication device to distribute the main lobe of each channel signal across different frequency bands, and determining the spectrum coverage range after frequency shifting; constructing an undirected graph model based on the channel conflict relationship between devices; establishing a channel allocation optimization model based on the undirected graph model, with the constraint of avoiding inter-user interference and the objective of maximizing the number of available channels in the system; and solving the optimization model to obtain the optimal channel allocation scheme. This invention effectively solves the interference problem in parallel transmission of multiple devices in RFID systems and environmental IoT scenarios. By reasonably configuring relevant device parameters, frequency shifting is achieved while effectively avoiding inter-signal harmonic interference, thus ensuring the reliability of multi-user parallel transmission. Furthermore, this method requires no hardware modification and is easy to implement in practice, providing an efficient and reliable solution for multi-user access in RFID systems and environmental IoT scenarios.

[0109] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0110] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0111] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0112] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment, whereby a series of operational steps are performed to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0113] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that, based on the technical solutions disclosed in the present invention, various modifications or variations that can be made by those skilled in the art without creative effort should be included within the scope of protection of the present invention.

Claims

1. A frequency-shift-based backscattering multi-user non-harmonicaUy interfering access method, characterized in that, Includes the following steps: Configure differentiated parameters for each communication device so that the main lobe of each channel signal is distributed in different frequency bands, and determine the spectrum coverage range after the signal frequency shift; Based on the channel conflict relationships between devices, an undirected graph model is constructed; Based on the undirected graph model, with the constraint of avoiding interference between users and the objective of maximizing the number of available channels in the system, a channel allocation optimization model is established. Solve the channel allocation optimization model to obtain the optimal channel allocation scheme; The differentiated parameters configured for each communication device include the following key transmission parameter combinations: data rate Backscatter link frequency ; for users The bandwidth range that needs to be allocated to it , where the left endpoint Avoiding users Bandwidth range occupied , , where the left endpoint right endpoint , , Represents the set of odd harmonic orders; the set of subcarrier period numbers. , ,in, The cardinality of a set corresponds to Channel after frequency shift; number of subcarrier cycles Uniquely identifies an independent communication channel and satisfies The constraint relationship, where ; Based on the channel conflict relationships between devices, an undirected graph model is constructed, including: constructing the undirected graph. , where the vertex set corresponding subcarrier cycle number set ,Right now ; Traverse the set of harmonic orders Each harmonic pair combination ,in , ∈ , ;calculate exist Bandwidth range of first harmonics and exist Bandwidth range of first harmonics If the judgment interval and There is an intersection, that is, it satisfies Then in the diagram Add connection vertices and undirected edge ,Right now Undirected graph models do not have self-loop edges, that is, for any edge set Does not contain elements .

2. The backscattering multi-user harmonic-free access method based on spectrum shifting according to claim 1, characterized in that, Construct a channel allocation optimization model, including: in, Given the set of channel allocation schemes to be solved, the optimization objective is... Indicates the cardinality of the selected channel set. Constraints ensure that the set Any two vertices There is no edge between them Connection means that there is no interference between corresponding users.

3. The backscattering multi-user harmonic-free access method based on spectrum shifting according to claim 1, characterized in that, Solving the channel allocation optimization model to obtain the optimal channel allocation scheme includes: initializing the maximum vertex subset. ,Right now For undirected acyclic graphs Perform connectivity analysis to identify connected subgraphs. , Represents the number of connected subgraphs; traverses the set of vertices. Filter out all isolated points and form a set of isolated points. For connected subgraphs , Solve for its vertex subset ,satisfy: ; subset of vertices of each connected subgraph With the set of isolated points Merge to generate the largest subset of vertices: ,in Global optimal solution Its base Maximize, corresponding to the maximum number of users that can be supported without interference; for users ,in, Configure relevant parameters ,in, Maintain data rates for each user Consistent, calculate the corresponding center frequency. Allocate bandwidth resources , where the left endpoint right endpoint ,ensure Interference-free transmission for a number of users.

4. The backscattering multi-user harmonic-free access method based on spectrum shifting according to claim 3, characterized in that, The method for finding the vertex subset of a connected subgraph is as follows: (a) Initialize three sets , , ; , , ; (b) Check the termination condition: if , ,but It is a subset of vertices that satisfy the constraints, output ,Record If the solution is a candidate, proceed to step (g); otherwise, continue to step (c). (c) From Choose any vertex ,Will join in , Update collection , , , ; Indicates that the corresponding set does not contain... Adjacent vertices; (d) Use the updated set Repeat step (b); (e) Complete the recursion at the current recursive level. After processing, from Remove from : ,Will join in : = ; (f) Return to step (b) and process. The remaining vertices; (g) All vertex subsets obtained by filtering satisfy the conditions of maximizing the cardinality of the set and minimizing the sum of its elements, i.e. Output .

5. A backscattering multi-user harmonic-free access system based on spectrum shifting, used to implement the method as described in any one of claims 1-4, characterized in that, Includes the following steps: The configuration module is used to configure differentiated parameters for each communication device, so that the main lobe of each channel signal is distributed in different frequency bands, and to determine the spectrum coverage range after the signal frequency shift. The first construction module is used to construct an undirected graph model based on the channel conflict relationship between devices; The second construction module is used to establish a channel allocation optimization model based on the undirected graph model, with the constraint of avoiding interference between users and the objective of maximizing the number of available channels in the system. The solution module is used to solve the channel allocation optimization model to obtain the optimal channel allocation scheme.

6. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium is used to store computer instructions, which, when executed by a processor, implement the backscattering multi-user harmonic interference-free access method based on spectrum shifting as described in any one of claims 1-4.

7. A computer device, characterized in that, The system includes a memory and a processor, which communicate with each other. The memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the backscattering multi-user harmonic interference-free access method based on spectrum shifting as described in any one of claims 1-4.

8. An electronic device, characterized in that, include: The device includes a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory to cause the electronic device to execute instructions to implement the backscattering multi-user harmonic interference-free access method based on spectrum shifting as described in any one of claims 1-4.

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