A method for minimizing information age access for large-scale Internet of Things scenarios

Abstract

The present invention proposes an information age minimization access method for large-scale Internet of Things scenarios, which relates to the technical field of wireless communications. First, the discretized time is divided into a number of small slots with a certain time length, and the number of user nodes in the network and the data packet arrival rate of the user nodes are obtained by a central base station to obtain a state equation of the probability of successful network transmission, and then the access channel probability in the state equation is optimized. By analyzing the expected optimal access channel probability and the solution of the monostable boundary optimal access channel probability within (0, 1), the optimal access channel probability is obtained. Finally, the central base station notifies each user node of the optimal access channel probability, and performs channel access and data packet transmission according to the optimal access channel probability, thereby minimizing the average peak information age of the network, and ensuring the stability of the network transmission performance while achieving the optimal information timeliness of the network.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communication, and more specifically, to an information age minimization access method for large-scale Internet of Things (IoT) scenarios. Background Art

[0002] The timeliness of information directly affects the performance of IoT applications in many IoT scenarios, such as environmental monitoring systems, unmanned aerial vehicle (UAV) networking, autonomous driving systems, or intelligent healthcare. IoT application systems are very sensitive to the timeliness of information. Timely and effective information can help decision-makers make correct judgments, while outdated information not only fails to assist decision-makers but may even cause misguidance, leading to a sharp decline in application performance. Therefore, how to improve the information timeliness of the system is crucial for ensuring system performance.

[0003] The age of information is an index used to characterize the timeliness of information, which is defined as the time interval between the generation time of the last successfully transmitted data packet and the current time. The peak age of information is widely used to characterize the age of information. It measures the maximum value that the age of information reaches before the data packet is successfully transmitted, and can effectively measure the age of information of user nodes in the network, further grasping the strength of the timeliness of each user node in the network.

[0004] In IoT application scenarios, due to limited channel resources, different user nodes in the network need to share the same channel resource. If multiple users choose to access the channel and transmit data packets at the same time, conflicts will occur, resulting in the transmission failure of all user nodes. To avoid the decline in communication quality caused by frequent conflicts, how to efficiently allocate and schedule all nodes in the network has always been a concern.

[0005] One of the characteristics of large-scale IoT is the large number of user nodes, which will lead to high communication overhead and control energy consumption in the implementation of existing centralized scheduling schemes. Therefore, for large-scale IoT or sensor networks, a distributed solution is needed to solve the access problem. The Carrier Sense Multiple Access (CSMA) protocol has been widely used in many IoT communication scenarios. The CSMA protocol discretizes time into several time slots and supports nodes to monitor the channel. After a node senses that the channel is idle, it will access the channel at the beginning of the time slot with a certain probability of accessing the channel, and then complete the transmission of the packet. Obviously, the design of the access channel probability directly determines the access quality of the CSMA protocol.

[0006] In the access probability design of existing solutions, only throughput and delay are often considered, while the age of information or the peak age of information is not taken into account, ignoring the value and significance of information timeliness in communication. In fact, the number of data packets in a low-latency system is small, while a large number of data packets in a high-throughput system need to queue in the buffer for a long time, which will both lead to a large age of information. As a communication metric that characterizes information value and measures information timeliness, the age of information is worthy of further optimization alone. How to optimize the age of information in the network under the CSMA protocol is still an open problem. To further improve the system quality and application performance of large-scale Internet of Things, it is urgent and necessary to study how to optimize the age of information under the CSMA protocol. Summary of the Invention

[0007] To solve the problem of how to minimize the peak age of information in the current large-scale Internet of Things scenario, the present invention proposes an access method for minimizing the age of information for large-scale Internet of Things scenarios, designs a network age of information optimization method based on the CSMA protocol for large-scale Internet of Things nodes, and determines the optimal access channel scheme, ensuring the stability of network transmission performance.

[0008] To achieve the above technical effects, the technical solution of the present invention is as follows:

[0009] An access method for minimizing the age of information for large-scale Internet of Things scenarios, including:

[0010] S1. Discretize the time of data packet transmission into equal-length time slots, and divide each time slot into several small time slots with a certain time length ratio;

[0011] S2. The central base station obtains the number of user nodes in the network and the data packet arrival rate of user nodes, and obtains the state equation of the network successful transmission probability;

[0012] S3. Optimize the access channel probability in the state equation, and respectively analyze the solutions of the expected optimal access channel probability and the single-stable boundary optimal access channel probability in the range of (0, 1);

[0013] S4. When both the expected optimal access channel probability and the single-stable boundary optimal access channel probability have solutions in the range of (0, 1), take the minimum value of the expected optimal access channel probability and the single-stable boundary optimal access channel probability as the optimal access channel probability;

[0014] S5. The central base station notifies each user node of the optimal access channel probability, and each user node performs channel access and data packet transmission according to the optimal access channel probability, realizing the minimization of the average peak age of information in the original network.

[0015] In this technical solution, when each user node detects that the channel is idle, if there are data packets to be sent in the buffer, it will perform channel access and data packet transmission according to the optimal access channel probability, minimizing the average peak age of information of the original network, thereby achieving the optimal information timeliness of the network.

[0016] Preferably, in step S1, using synchronization technology, first discretize the time of data packet transmission into equal-length time slots, and then based on the CSMA protocol, divide each time slot into several small time slots with a duration ratio of a, complete the alignment and synchronization of each user node in the small time slots, and listen to the channel in any small time slot before sending data, avoiding multiple nodes sending data in the same time slot, forming data congestion and collision, resulting in a slow network speed.

[0017] Preferably, in step S2, adjust the buffer size of each user node to a single data packet, and each node adopts a first-come, first-served queue service strategy; obtain the number of user nodes n and the data packet arrival rate λ of the user nodes in the Internet of Things from the central base station, where the arrival of data packets is a Bernoulli process with a parameter of λ.

[0018] Preferably, in step S2, the state equation of the network successful transmission probability p is:

[0019]

[0020] Among them, n represents the number of user nodes, λ represents the data packet arrival rate of the user nodes, a represents the duration ratio of the small time slot, and q represents the access channel probability. Here, the state equation of the network successful transmission probability can be used to determine whether the network is in a single-stable state or a double-stable state.

[0021] Preferably, in step S3, the solution expression of the expected optimal access channel probability q M is:

[0022]

[0023] By substituting parameters to solve, q M is obtained, where W 0 is the Lambert W function; if q M is not within the interval (0, 1), record q M as no solution.

[0024] Preferably, in step S3, the solution expression of the single-stable state boundary optimal access channel probability q B is:

[0025]

[0026] If q BIf it does not exist within the interval (0, 1), then denote q B as having no solution.

[0027] Preferably, if the expected optimal access channel probability q M has no solution within (0, 1), then the optimal access channel probability q* is q B ; if the optimal access channel probability q at the monostable boundary B has no solution within (0, 1), then the optimal access channel probability q* is; if q M and q B both have solutions within (0, 1), then the optimal access channel probability is q* = min{q B , q M}.

[0028] Herein, ensuring the optimal access channel probability of the network under monostable conditions improves the stability of network transmission and avoids the situation where the operating working point of the network suddenly drops from the original stable point to a very small second stable state solution under bistable conditions, resulting in a sharp decline in the network transmission success probability and deterioration of transmission performance.

[0029] Preferably, after step S5, it further includes verifying the effect of the age-of-information minimization access method using the network average peak age-of-information verification. According to the Bernoulli process of packet arrival and the first-come-first-served queue service policy under a single buffer size, the average peak age-of-information A of network nodes under this setting is obtained, and the calculation formula is as follows:

[0030]

[0031] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0032] The present invention proposes an age-of-information minimization access method for large-scale Internet of Things scenarios. First, the discretized time is divided into several small time slots with a certain time duration ratio. The central base station obtains the number of user nodes and the packet arrival rate of user nodes in the network to obtain the state equation of the network successful transmission probability. Then, the access channel probability in the state equation is optimized. By analyzing the solutions of the expected optimal access channel probability and the optimal access channel probability at the monostable boundary within (0, 1), the optimal access channel probability is obtained. Finally, the central base station informs each user node of the optimal access channel probability, and channel access and packet transmission are performed according to the optimal access channel probability, realizing the minimization of the network average peak age-of-information. When selecting the optimal access channel probability, different stable state conditions during network transmission are fully considered, ensuring the stability of network transmission performance while achieving the optimal information timeliness of the network. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1Schematic flowchart of the age-of-information minimization access method for large-scale Internet of Things scenarios proposed in Embodiment 1 of the present invention;

[0034] Figure 2 Schematic diagram of the application scenario of the age-of-information minimization access method for large-scale Internet of Things scenarios proposed in Embodiment 1 of the present invention;

[0035] Figure 3 Schematic flowchart of the optimal access channel probability optimization process proposed in Embodiment 2 of the present invention;

[0036] Figure 4 Schematic diagram of the optimization effect of the age-of-information minimization access method for large-scale Internet of Things scenarios proposed in Embodiment 3 of the present invention; Detailed implementation manners

[0037] The drawings are only for illustrative purposes and should not be construed as limitations on this patent;

[0038] For a better illustration of this embodiment, some parts of the drawings are omitted, enlarged or reduced, which do not represent the actual size;

[0039] For those skilled in the art, it is understandable that some well-known content descriptions in the drawings may be omitted.

[0040] The technical solutions of the present invention will be further described below with reference to the drawings and embodiments.

[0041] The description of the positional relationship in the drawings is only for illustrative purposes and should not be construed as limitations on this patent;

[0042] Embodiment 1

[0043] As Figure 1 shown, this embodiment proposes an age-of-information minimization access method for large-scale Internet of Things scenarios. Referring to Figure 1 , the method includes the following steps:

[0044] S1. Discretize the time of data packet transmission into equal-length time slots, and divide each time slot into several small time slots with a certain duration ratio;

[0045] Using synchronization technology, first discretize the time of data packet transmission into equal-length time slots, and then based on the CSMA protocol, divide each time slot into several small time slots with a duration ratio of a, complete the alignment and synchronization of each user node in the small time slots, and listen to the channel in any small time slot before sending data. In this embodiment, it is assumed that the CSMA protocol in the network divides each time slot into 10 small time slots, that is, the ratio of each small time slot a = 0.1. The transmission and channel access of each data packet together require a complete time slot.

[0046] S2. Obtain the number of user nodes in the network and the packet arrival rate of user nodes from the central base station, and derive the state equation of the network successful transmission probability;

[0047] Among them, adjust the cache size of each user node to a single packet, and each node adopts a first-come-first-served queue service strategy; obtain the number of user nodes n and the packet arrival rate λ of user nodes in the Internet of Things from the central base station. The arrival of packets is a Bernoulli process with parameter λ. The state equation of the network successful transmission probability p is:

[0048]

[0049] Among them, n represents the number of user nodes, λ represents the packet arrival rate of user nodes, a represents the proportion of the hour slot duration, and q represents the access channel probability. In this embodiment, the packet arrival rate λ of each user node is 0.005.

[0050] S3. Optimize the access channel probability in the state equation, and respectively analyze the solutions of the expected optimal access channel probability and the monostable boundary optimal access channel probability in the range of (0, 1);

[0051] S4. When both the expected optimal access channel probability and the monostable boundary optimal access channel probability have solutions in the range of (0, 1), take the minimum value of the expected optimal access channel probability and the monostable boundary optimal access channel probability as the optimal access channel probability;

[0052] S5. The central base station informs each user node of the optimal access channel probability, and each user node performs channel access and packet transmission according to the optimal access channel probability, so as to minimize the average peak age of information of the original network.

[0053] After that, all user nodes set the corresponding access channel probabilities. When each user node detects that the channel is idle, if there are packets to be sent in the buffer, it performs channel access and packet transmission according to the optimal access channel probability. As Figure 2 shown, since the optimal access channel probability is designed for minimizing the peak age of information, the average peak age of information of the original network can be minimized under the channel access of the optimal access channel probability, thereby achieving the optimal information timeliness of the network.

[0054] Embodiment 2

[0055] As Figure 3 shown, in this embodiment, the specific process of obtaining the optimal access channel probability is as follows:

[0056] The solution formula of the expected optimal access channel probability q M is as follows:

[0057]

[0058] Substitute the known parameters into the above solution expression to solve for q M , where the known parameters include: the proportion of the small time slot duration a, the number of user nodes n, the packet arrival rate λ of the user nodes, and W 0 is the Lambert W function; if q M is not within the interval (0, 1), record q M as having no solution.

[0059] The solution formula for the monostable boundary optimal access channel probability q B is as follows:

[0060]

[0061] Perform root finding within the interval (0, 1). The monostable boundary optimal access channel probability q B is the non-zero real solution of the above solution equation. The solution method can be the bisection method, the secant method, or the inverse quadratic interpolation method. If q B does not exist within the interval (0, 1), then record q B as having no solution.

[0062] If the expected optimal access channel probability q M has no solution within (0, 1), then the optimal access channel probability q* is q B ; if the monostable boundary optimal access channel probability q B has no solution within (0, 1), then the optimal access channel probability q* is q M ; if q M and q B both have solutions within (0, 1), then the optimal access channel probability is q* = min{q B , q M}.

[0063] Example 3

[0064] In this example, the effect of the age-of-information minimization access method is verified by using the network average peak age of information. According to the Bernoulli process of packet arrival and the first-come-first-served queue service policy under a single buffer size, the average peak age of information A of the network nodes in this setting is obtained, and the calculation formula is as follows:

[0065]

[0066] See Figure 4, assume that in the network, the CSMA protocol divides each time slot into 10 small time slots, that is, the proportion of each small time slot is a = 0.1. The transmission and channel access of each data packet together require a complete time slot, and the packet arrival rate of each user node is λ = 0.005. Under different numbers of network user nodes, when the channel access probability takes a constant value of 0.001 or adopts the optimal channel access probability optimized in this embodiment, the comparison of the average peak age of information in the network is as follows Figure 4 As shown, by using the optimal channel access probability obtained in this embodiment, the minimum average peak age of the network can be achieved, and the timeliness of information in the network has been greatly improved compared with the original fixed value.

[0067] Obviously, the above embodiments of the present invention are only examples for clearly explaining the present invention, and are not limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A method for minimizing information age access for large-scale Internet of Things scenarios, characterized in that: include: S1. Discretize the time of data packet transmission into time slots of equal length, and divide each time slot into several small slots with a certain duration ratio; S2. The central base station obtains the number of user nodes in the network and the packet arrival rate of the user nodes, and derives the state equation of the probability of successful transmission of the network based on the number of user nodes and the packet arrival rate of the user nodes; S3. Optimize the access channel probability in the state equation: analyze the solutions of the expected optimal access channel probability and the monostable boundary optimal access channel probability in the range of (0, 1) respectively; S4. When both the expected optimal access channel probability and the monostable boundary optimal access channel probability have solutions in the range of (0, 1), the minimum value of the expected optimal access channel probability and the monostable boundary optimal access channel probability is taken as the optimal access channel probability; S5. The central base station informs each user node of the optimal access channel probability. Each user node performs channel access and data packet transmission according to the optimal access channel probability, thereby minimizing the average peak information age of the original network.

2. The information age minimization access method for large-scale Internet of Things scenarios according to claim 1 is characterized in that: In step S1, the synchronization technology is used to discretize the data packet transmission time into time slots of equal length, and then based on the CSMA protocol, each time slot is divided into several small slots with a duration ratio of a, so as to complete the alignment and synchronization of each user node in the small slot, and monitor the channel in any small slot before sending data.

3. The information age minimization access method for large-scale Internet of Things scenarios according to claim 2 is characterized in that: In step S2, the cache size of each user node is adjusted to a single data packet, and each node adopts a first-come-first-served queue service strategy; the number of user nodes n in the Internet of Things and the data packet arrival rate λ of the user nodes are obtained from the central base station, where the arrival of the data packet is a Bernoulli process with a parameter λ.

4. The information age minimization access method for large-scale Internet of Things scenarios according to claim 3 is characterized in that: In step S2, the state equation of the network successful transmission probability p is: Where n represents the number of user nodes, λ represents the data packet arrival rate of the user nodes, a represents the proportion of small slot duration, and q represents the access channel probability.

5. The information age minimization access method for large-scale Internet of Things scenarios according to claim 4 is characterized in that: In step S3, the expected optimal access channel probability q M The solution expression is: Where W0 is the Lambert W function; if q M Not in the interval (0, 1), record q M There is no solution.

6. The information age minimization access method for large-scale Internet of Things scenarios according to claim 5 is characterized in that: In step S3, the monostable boundary optimal access channel probability q B The solution expression is: If q B does not exist in the interval (0, 1), then q B There is no solution.

7. The information age minimization access method for large-scale Internet of Things scenarios according to claim 6 is characterized in that: If the expected optimal access channel probability q M There is no solution in (0, 1), then the optimal access channel probability q* is q B .

8. The information age minimization access method for large-scale Internet of Things scenarios according to claim 6 is characterized in that: If the monostable boundary optimal access channel probability q B There is no solution in (0, 1), then the optimal access channel probability q* is q M .

9. The information age minimization access method for large-scale Internet of Things scenarios according to claim 6 is characterized in that: If q M and q B There is a solution in (0, 1), then the optimal access channel probability is q*=min{q B ,q M }.

10. The information age minimization access method for large-scale Internet of Things scenarios according to any one of claims 4, 7 to 9, characterized in that: After step S5, the method further includes verifying the effect of the information age minimization access method by using the network average peak information age verification. According to the Bernoulli process of data packet arrival and the first-come-first-served queue service strategy under a single cache size, the average peak information age A of the network node under this setting is obtained. The calculation formula is as follows:

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