Passive Internet of Things node media access control method, system, device and medium

Abstract

The present invention discloses a passive Internet of Things node medium access control method, system, device and medium, wherein the method comprises: S1, when a wireless sensor node has a data transmission demand, initializing the number of conflicts i=0; S2, updating the priority K of the node data transmission according to the current remaining energy E of the node; initializing the fixed waiting time T1 and the random backoff time T2 of the node according to the priority K; S3, monitoring the channel state, if the channel is idle within the T1 time, executing step S4; S4, the wireless sensor node backs off for T2 time and waits; S5, sending data, if a confirmation signal from a receiving end is received, the data is sent successfully, otherwise, executing step S6; S6, the wireless sensor node updates its own number of conflicts i=i+1, if i is greater than a preset conflict upper limit i max , then the data transmission fails. The present invention solves the channel allocation problem when terminal nodes are simultaneously connected to readers, and can be widely used in the field of passive Internet of Things.

Description

Technical Field

[0001] The present invention relates to the field of passive Internet of Things, and in particular to a passive Internet of Things node medium access control method, system, device and medium. Background Art

[0002] In recent years, wireless sensor networks have been widely used in smart home, environmental monitoring, intelligent control, medical and health care, etc. Since the terminal nodes are small in size and easy to deploy, they usually form a self-organizing wireless network with nearby wireless devices to monitor the surrounding environment information.

[0003] However, the size of the terminal node limits the capacity of its own battery. Replacing batteries for a large number of nodes is costly or even impossible, which brings huge challenges to the deployment and subsequent maintenance of wireless sensor networks. The passive Internet of Things has solved the above problems very well. The terminal node does not connect to an external power supply or carry a battery, and it collects radio frequency energy in the environment to power the node. As an ultra-low power communication method, environmental backscatter communication has become the preferred communication method for the passive Internet of Things.

[0004] The medium access control (MAC) protocol determines how the wireless channel is used, allocates limited wireless communication resources between wireless sensor nodes, and is used to build the underlying infrastructure of the wireless sensor network system. Traditional wireless sensor networks are mostly battery-powered, and the research focus of the medium access control protocol is to reduce network energy consumption and extend the survival time of nodes. However, the terminal nodes that use environmental backscatter communication obtain radio frequency energy in the environment to maintain the normal operation of the node, and the remaining energy of the node has the characteristic of dynamic change. In addition, the terminal node should reduce the collision probability and reduce the energy loss caused by node collision. At this time, the focus becomes how to use the energy available to the node to reduce the collision probability of the node. Therefore, it is urgent to design a medium access control protocol for passive IoT nodes based on environmental backscatter communication. Summary of the invention

[0005] In order to solve at least one of the technical problems existing in the prior art to a certain extent, the object of the present invention is to:

[0006] The technical solution adopted by the present invention is:

[0007] A passive Internet of Things node medium access control method comprises the following steps:

[0008] S1. When the wireless sensor node has a data transmission requirement, the number of conflicts i is initialized to 0, and then step S2 is executed;

[0009] S2, the wireless sensor node updates the priority K of node data transmission according to the current remaining energy E of the node; initializes the fixed waiting time T1 and random backoff time T2 of the node according to the priority K, and then executes step S3;

[0010] S3, the wireless sensor node monitors the channel status, if the channel is idle within the T1 time length, execute step S4, otherwise continue to execute step S2;

[0011] S4, the wireless sensor node backs off for T2 time and waits, and after the backoff phase ends, executes step S5;

[0012] S5, the wireless sensor node sends data. If a confirmation signal is received from the receiving end, the data is sent successfully, otherwise, step S6 is executed;

[0013] S6: The wireless sensor node updates its own conflict times i=i+1. If i is greater than the preset conflict upper limit i max , then the data transmission fails, otherwise execute step S2.

[0014] Furthermore, in step S2, the design scheme of the node data transmission priority K has the following characteristics: the node with higher residual energy has smaller K, which represents a higher priority of the node. The minimum value of K is 1, and the maximum value is the granularity n of the node priority classification.

[0015] Furthermore, the priority K is calculated as follows:

[0016]

[0017] Among them, E max is the upper limit of energy that a node can obtain, E min It is the energy threshold to maintain the normal operation of the node, and n is the granularity of node priority classification.

[0018] Furthermore, in step S2, the design scheme of the node fixed waiting time T1 has the following characteristics:

[0019] T1 is determined by the formula T1 = g(K)*Δt, where g(K) is a monotonically increasing function that returns an integer value, and Δt is the duration of a unit time slot;

[0020] Based on this design, it can be seen that nodes with different priorities have different fixed waiting times T1, and nodes with higher priorities have lower T1, and have higher transmission opportunities than nodes with lower priorities.

[0021] Furthermore, in step S2, the design scheme of the node random backoff duration T2 has the following characteristics:

[0022] T2 is determined by the formula T2=Rand(A,B)*Δt. Rand(A,B) returns a random integer in the range [A,B). All nodes A=g(K), and the node with non-lowest priority B=g(K+1). The value of the node with the lowest priority B can be an integer greater than g(K).

[0023] Furthermore, when the node monitors the channel in step S3 and when the node backs off and waits in step S4, the RF energy in the environment can be obtained to supplement the remaining energy of the node. Therefore, the priority of low-priority nodes will gradually increase during multiple monitoring and backing off processes, greatly improving the probability of node transmission and ensuring the fairness of the nodes.

[0024] Another technical solution adopted by the present invention is:

[0025] An environmental backscatter passive Internet of Things system comprises a wireless sensor node and a receiving device, wherein the wireless sensor node is controlled by using the above-mentioned passive Internet of Things node medium access control method.

[0026] Furthermore, the receiving device is a reader.

[0027] Another technical solution adopted by the present invention is:

[0028] A passive Internet of Things node medium access control device, comprising:

[0029] at least one processor;

[0030] at least one memory for storing at least one program;

[0031] When the at least one program is executed by the at least one processor, the at least one processor implements the above method.

[0032] Another technical solution adopted by the present invention is:

[0033] A computer-readable storage medium stores a program executable by a processor, wherein the program executable by the processor is used to execute the method described above when executed by the processor.

[0034] The beneficial effects of the present invention are as follows: the present invention introduces two concepts, fixed waiting time and random backoff time, and reduces the collision probability of nodes with different priorities by distinguishing different fixed waiting time. By distinguishing different random backoff time, the collision probability of nodes with the same priority is reduced. In addition, the present invention provides a priority mechanism, so that nodes with higher residual energy have higher priority access to the channel, reducing the risk of communication failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the embodiments of the present invention or the drawings of related technical solutions in the prior art are introduced below. It should be understood that the drawings introduced below are only for the convenience of clearly describing some embodiments of the technical solutions of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 It is a topological structure diagram applied to the environment backscatter passive Internet of Things in an embodiment of the present invention;

[0037] Figure 2 This is a passive Internet of Things node medium access control protocol algorithm flow based on environmental backscatter communication in an embodiment of the present invention. DETAILED DESCRIPTION

[0038] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limitations of the present invention. For the step numbers in the following embodiments, they are only provided for the convenience of explanation, and the order between the steps is not limited in any way, and the execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0039] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0040] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0041] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0042] like Figure 1The figure shows an environment reflection scattering passive Internet of Things composed of wireless sensor nodes and readers. In order to connect multiple terminal nodes based on environment backscattering communication to the reader and use the energy available to the nodes to reduce the probability of node collision, this embodiment provides a passive Internet of Things node medium access control protocol based on environment backscattering communication, see Figure 2 , including the following steps:

[0043] S101, when the wireless sensor node has a data transmission demand, initialize the number of conflicts i=0, and then execute step S102;

[0044] S102: The wireless sensor node updates the priority of node data transmission according to the current remaining energy E of the node. Where E max is the upper limit of energy that a node can obtain, E min The energy threshold for maintaining the normal operation of the node, n is the granularity of the node priority classification. Finally, the fixed waiting time T1 and the random backoff time T2 of the node are initialized according to K, and then step S103 is executed;

[0045] S103, the wireless sensor node monitors the channel status, if the channel is idle within the T1 time length, execute step S104, otherwise continue to execute step S102;

[0046] S104, the wireless sensor node backs off for T2 time and waits, and after the back-off phase ends, executes step S105;

[0047] S105, the wireless sensor node sends data. If a confirmation signal is received from the receiving end, the data is sent successfully, otherwise, step S106 is executed;

[0048] S106: The wireless sensor node updates its own conflict times i=i+1. If i is greater than the upper limit of conflicts allowed by the node i max , then the data transmission fails, otherwise execute step S102.

[0049] As an optional implementation, in step S102, the design scheme of the node data transmission priority K has the following characteristics: the node with higher residual energy has a smaller K, which represents a higher priority of the node. The minimum value of K is 1, and the maximum value is the granularity n of the node priority classification.

[0050] As an optional implementation, in step S102, the design scheme of the node fixed waiting time T1 has the following characteristics: T1 is determined by the formula T1 = g(K)*Δt, g(K) is a single increasing function and returns an integer value, and Δt is the duration of the unit backoff time slot. From this design scheme, it can be seen that nodes with different priorities have different fixed waiting times T1, and the higher the priority of the node, the lower the T1, and the node has a higher transmission opportunity than the low priority node.

[0051] Further as an optional implementation, in step S102, the design scheme of the node random backoff time T2 has the following characteristics: T2 is determined by the formula T2 = Rand(A, B)*Δt, Rand(A, B) returns a random integer in the range [A, B), all nodes A = g(K), the node B with non-lowest priority = g(K+1), and the value of the node B with the lowest priority can be an integer greater than g(K).

[0052] As an optional implementation, when the node monitors the channel in step S103 and when the node backs off and waits in step S104, the RF energy in the environment can be obtained to supplement the remaining energy of the node. Therefore, the priority of low-priority nodes will gradually increase during multiple monitoring and backing off processes, greatly improving the probability of node transmission and ensuring the fairness of the nodes.

[0053] As can be seen from the above, the method of this embodiment has the following characteristics: the terminal node adaptively adjusts the fixed waiting time and random backoff time of the node according to the residual energy of the node itself. The node with higher residual energy has a higher transmission priority. High-priority nodes have a shorter fixed waiting time than low-priority nodes. The collision probability between nodes of different priorities is reduced by distinguishing the fixed waiting time of nodes of different priorities. Nodes of the same priority have the same fixed waiting time, and the random backoff time is randomly taken from a certain range, which further reduces the collision probability between nodes of the same priority.

[0054] The above method is explained in detail below in conjunction with specific embodiments.

[0055] Consider a wireless sensor network that includes one reader and four wireless sensor nodes. The residual energy of node 1> the residual energy of node 2> the residual energy of node 3> the residual energy of node 4. Among them, the residual energy of node 1 is E1=0.92(E max -E min ), the remaining energy of node 2 is E2=0.85(E max -E min ), the remaining energy of node 3 is E3=0.51(E max -E min), the remaining energy of node 4 is E4=0.43(E max -E min ), the granularity of the protocol instance node priority classification is n=5, and the duration of the unit time slot is Δt. The node with priority 1 is T1=Δt, T2=Rand(0,8)*Δt, the node with priority 2 is T1=9*Δt, T2=Rand(0,16)*Δt, the node with priority 3 is T1=25*Δt, T2=Rand(0,32)*Δt, the node with priority 4 is T1=57*Δt, T2=Rand(0,64)*Δt, the node with priority 5 is T1=121*Δt, T2=Rand(0,128)*Δt. Assuming that all four nodes have the need for data transmission, the operation steps of the protocol when applied to the above passive Internet of Things are as follows:

[0056] S201, node 1, node 2, node 3, node 4 initialize their own conflict times i = 0;

[0057] S202. The node updates the node data transmission priority according to the current remaining energy. The priority of node 1 is K=1, the fixed waiting time T1=Δt, and the random backoff time T2=6*Δt. The priority of node 2 is K=1, the fixed waiting time T1=Δt, and the random backoff time T2=4*Δt. The priority of node 3 is K=3, the fixed waiting time T1=25*Δt, and the random backoff time T2=17*Δt. The priority of node 4 is K=3, the fixed waiting time T1=25*Δt, and the random backoff time T2=26*Δt.

[0058] S203, node 1, node 2, node 3, node 4 monitor the channel status, node 1 and node 2 have a fixed waiting time of T1 = Δt, the channel is idle within Δt, and step S204 is executed. The fixed waiting time of node 3 and node 4 is T1 = 25*Δt. When node 1 and node 2 finish executing step S204 to send data, node 3 and node 4 are still monitoring the channel. At this time, the channel is busy, so node 1 and node 2 turn to execute step S202.

[0059] S204, the random backoff duration of node 1 is T2=6*Δt, and the random backoff duration of node 2 is T2=4*Δt. Therefore, node 2 ends the backoff phase before node 1. When node 2 executes step S205, node 1 freezes its own backoff timer. At this time, the backoff duration of node 1 is still 2*Δt.

[0060] S205, Node 2 sends data and successfully receives a confirmation signal from the receiving end, indicating that Node 2 has successfully sent data.

[0061] At this time, there are still nodes 1, 3, and 4 that have not successfully sent data. The remaining duration of the backoff timer of node 1 is 2*Δt, which is less than the fixed waiting time T1=25*Δt of nodes 3 and 4. Therefore, node 1 sends data after the timer ends and successfully receives the confirmation signal from the receiving end. Node 1 sends data successfully.

[0062] Finally, there are still nodes 3 and 4 that have not successfully sent data. Since nodes 3 and 4 have collected RF energy in the environment in the cycles of steps S202 and S203 for several times, they will calculate an updated priority, fixed waiting time, and random backoff time according to the latest remaining energy state of the node. After that, the data sending process of nodes 3 and 4 is similar to the sending example of nodes 1 and 2.

[0063] In summary, the method of this embodiment has the following beneficial effects compared with the prior art:

[0064] (1) The embodiment of the present invention proposes a passive IoT node medium access control protocol based on environmental backscatter communication. Compared with the prior art, it does not require strict time synchronization and can also effectively reduce the probability of collision between nodes. The embodiment of the present invention introduces two concepts: fixed waiting time and random backoff time. By distinguishing different fixed waiting times, the collision probability between nodes of different priorities is reduced. By distinguishing different random backoff times, the collision probability between nodes of the same priority is reduced.

[0065] (2) Since wireless sensor nodes using environmental backscatter communication usually use supercapacitors to store RF energy in the environment, the amount of energy stored is much smaller than the solution of traditional wireless sensor nodes using battery energy storage, and nodes with lower residual energy will bear a higher risk of communication failure. Therefore, the embodiment of the present invention provides a priority mechanism, so that nodes with higher residual energy have higher priority access to the channel, reducing the risk of communication failure.

[0066] This embodiment also provides an environment reflection scattering passive Internet of Things system, including a wireless sensor node and a receiving device, wherein the wireless sensor node adopts Figure 2 The control method shown is used for control.

[0067] The environmental backscattering passive Internet of Things system of this embodiment has a corresponding relationship with a passive Internet of Things node media access control method provided by the method embodiment of the present invention, and therefore has the corresponding functions and beneficial effects of the method.

[0068] This embodiment also provides a passive Internet of Things node medium access control device, including:

[0069] at least one processor;

[0070] at least one memory for storing at least one program;

[0071] When the at least one program is executed by the at least one processor, the at least one processor implements the above method.

[0072] A passive Internet of Things node media access control device of this embodiment can execute a passive Internet of Things node media access control method provided by the method embodiment of the present invention, can execute any combination of implementation steps of the method embodiment, and has the corresponding functions and beneficial effects of the method.

[0073] The present application also discloses a computer program product or a computer program, which includes a computer instruction stored in a computer-readable storage medium. A processor of a computer device can read the computer instruction from the computer-readable storage medium, and the processor executes the computer instruction, so that the computer device executes Figure 2 The method shown.

[0074] This embodiment also provides a storage medium, which stores instructions or programs that can execute a passive Internet of Things node media access control method provided by an embodiment of the method of the present invention. When the instructions or programs are run, any combination of implementation steps of the method embodiment can be executed, and the corresponding functions and beneficial effects of the method can be obtained.

[0075] In some selectable embodiments, the function / operation mentioned in the block diagram may not occur in the order mentioned in the operation diagram. For example, depending on the function / operation involved, the two boxes shown in succession can actually be executed substantially simultaneously or the boxes can sometimes be executed in reverse order. In addition, the embodiment presented and described in the flow chart of the present invention is provided by way of example, for the purpose of providing a more comprehensive understanding of technology. The disclosed method is not limited to the operation and logic flow presented herein. Selectable embodiments are expected, wherein the order of various operations is changed and the sub-operation of a part for which is described as a larger operation is performed independently.

[0076] In addition, although the present invention is described in the context of functional modules, it should be understood that, unless otherwise specified, one or more of the functions and / or features described may be integrated into a single physical device and / or software module, or one or more functions and / or features may be implemented in separate physical devices or software modules. It is also understood that a detailed discussion of the actual implementation of each module is unnecessary for understanding the present invention. More specifically, in view of the properties, functions, and internal relationships of the various functional modules in the device disclosed herein, the actual implementation of the module will be understood within the conventional skills of the engineer. Therefore, those skilled in the art can implement the present invention set forth in the claims without excessive experimentation using ordinary techniques. It is also understood that the specific concepts disclosed are merely illustrative and are not intended to limit the scope of the present invention, which is determined by the full scope of the appended claims and their equivalents.

[0077] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0078] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0079] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0080] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0081] In the above description of this specification, the description with reference to the terms "one embodiment / example", "another embodiment / example" or "certain embodiments / examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0082] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

[0083] The above is a specific description of the preferred implementation of the present invention, but the present invention is not limited to the above embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A passive Internet of Things node media access control method, characterized in that: The following steps are involved: S1. When the wireless sensor node has a data transmission requirement, the number of conflicts i is initialized to 0, and then step S2 is executed; S2, the wireless sensor node updates the priority K of node data transmission according to the current remaining energy E of the node; initializes the fixed waiting time T1 and random backoff time T2 of the node according to the priority K, and then executes step S3; S3, the wireless sensor node monitors the channel status, if the channel is idle within the T1 time length, execute step S4, otherwise continue to execute step S2; S4, the wireless sensor node backs off for T2 time and waits, and after the backoff phase ends, executes step S5; S5, the wireless sensor node sends data. If a confirmation signal is received from the receiving end, the data is sent successfully, otherwise, step S6 is executed; S6: The wireless sensor node updates its own conflict times i=i+1. If i is greater than the preset conflict upper limit i max , then the data transmission fails, otherwise, execute step S2; In step S2, the design scheme of the node fixed waiting time T1 has the following characteristics: T1 is determined by the formula T1 = g(K)*Δt, where g(K) is a monotonically increasing function that returns an integer value, and Δt is the duration of a unit time slot; Based on this design, it can be seen that nodes with different priorities have different fixed waiting times T1, and nodes with higher priorities have lower T1, and have higher transmission opportunities than nodes with lower priorities; In step S2, the design scheme of the node random backoff duration T2 has the following characteristics: T2 is determined by the formula T2=Rand(A,B)*Δt. Rand(A,B) returns a random integer in the range [A,B). All nodes A=g(K), and the node with non-lowest priority B=g(K+1). The value of the node with the lowest priority B can be an integer greater than g(K).

2. A passive Internet of Things node media access control method according to claim 1, characterized in that: In step S2, the design scheme of the priority K of node data transmission has the following characteristics: The higher the energy of the node, the smaller K is, which means the node has a higher priority. The minimum value of K is 1, and the maximum value is the granularity n of the node priority classification.

3. A passive Internet of Things node media access control method according to claim 2, characterized in that: The priority level K is calculated as follows: Among them, E max is the upper limit of energy that a node can obtain, E min It is the energy threshold to maintain the normal operation of the node, and n is the granularity of node priority classification.

4. A passive Internet of Things node media access control method according to claim 1, characterized in that: When the node monitors the channel in step S3 and when the node backs off and waits in step S4, the RF energy in the environment can be obtained to supplement the remaining energy of the node. Therefore, the priority of low-priority nodes will gradually increase during multiple monitoring and backing off processes, greatly improving the probability of node transmission and ensuring the fairness of the nodes.

5. An environmental backscatter passive Internet of Things system, characterized in that: It comprises a wireless sensor node and a receiving device, wherein the wireless sensor node is controlled by a passive Internet of Things node medium access control method as described in any one of claims 1 to 4.

6. The environmental backscatter passive Internet of Things system according to claim 5, characterized in that: The receiving device is a reader.

7. A passive Internet of Things node media access control device, characterized in that: include: at least one processor; at least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor implements the method according to any one of claims 1 to 4.

8. A computer-readable storage medium storing a program executable by a processor, characterized in that: The processor-executable program is used to perform the method according to any one of claims 1 to 4 when executed by the processor.

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