Irregular repeated time slot ALOHA protocol method based on multi-packet reception

Abstract

The invention provides an irregular repeated time slot ALOHA protocol method based on multi-packet reception, which belongs to the technical field of wireless communication, introduces a multi-packet reception capability MR on the basis of a traditional IRSA protocol, and relaxes a decoding condition from a conflict-free condition to a condition that the number of conflict data packets is less than or equal to MR, thereby reducing the number of iterations of decoding, and improving the decoding efficiency. And the data packet transmission capability of the system can be improved, the decoding capability, throughput and packet loss rate performance under high channel load can be improved, and the performance superior to that of a traditional random access protocol can be obtained in a massive machine communication scene. The scheme is verified through actual experiments, and the superiority of the scheme is shown.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, specifically relating to an irregular repetitive time slot ALOHA protocol method based on multi-packet reception. Background Technology

[0002] The Internet of Things (IoT) is considered a rapidly developing new paradigm in the internet age. With the rapid development of IoT, more and more terminal devices will be applied in more complex communication scenarios. At the same time, many problems and challenges arise. As a key scenario supporting machine-to-machine communication in the 5G standard, massive machine-type communications (mMTC) needs to support the rapidly growing IoT industry. With the continuous increase in mobile internet terminal devices and the enrichment of communication scenarios, higher requirements are placed on the availability and robustness of access solutions. Existing access solutions can no longer meet these needs.

[0003] The IRSA protocol addresses the issues of high collision probability and low throughput in massive machine-type communication scenarios. However, the initial condition for using this scheme for iterative decoding is that there are "clean" time slots in the current channel without collisions. It is this characteristic that causes the decoding capability of IRSA to decrease significantly under high channel load, and its throughput performance to drop rapidly, even falling behind traditional access schemes. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies and improve the decoding capability and throughput of the IRSA protocol under high channel load, this invention provides an irregular repetitive time slot ALOHA protocol method based on multi-packet reception.

[0005] The solution to the technical problem of this invention is an ALOHA protocol method based on multi-packet reception with irregular repetitive time slots, comprising the following steps: S1: Construct the MR-IRSA system model; The MR-IRSA system model is based on the IRSA protocol model, and adds multi-packet reception capability to the multi-packet reception channel in the IRSA protocol model. MR; The IRSA protocol model includes a transmitter, a selector, a multi-packet reception channel, and a receiver; the range of the multi-packet reception capability is... MR ≥1; S2: Based on the MR-IRSA system model, the sending end sends data packet copies according to a pre-given probability distribution. The sending end sends data packet copies in different time slots, and the sending end sends at most one data packet copy in each time slot; S3: The receiving end receives all data packet copies and constructs a bipartite graph using the received data packet copies; the bipartite graph includes time slot nodes and terminal nodes; wherein, a time slot node represents all time slots; a terminal node represents the sending end that sends a data packet copy in a time slot node; if the sending end j sends a data packet copy in time slot i, there is an edge connecting time slot node i and sending end node j; if the data packet copy sent by sending end node j in time slot i is successfully decoded, this edge is a dashed line, otherwise it is a solid line; Iterate through all time slot nodes in the bipartite graph. For any time slot node, if the number of solid lines connecting it to the time slot node is... If the multi-packet reception capability (MR) is less than or equal to the multi-packet reception capability (MR), then all data packet replicas in the time slot node are decoded. If a data packet replica satisfies any one of the decoding conditions, the decoding is successful. At the same time, the bipartite graph is updated, and all solid lines connecting the time slot nodes are changed to dashed lines. Based on the decoded data packet replica, the sender corresponding to the decoded data packet replica is determined, and the sender corresponding to the decoded data packet replica is marked as successfully decoded. The bipartite graph is updated, and all terminal nodes corresponding to the senders connected to the time slot node are found. All solid lines connecting the terminal nodes corresponding to the senders are changed to dashed lines. If the number of solid lines connected to the time slot node If the received packet count (MR) exceeds the multi-packet reception capacity (MR), decoding is not possible, and the process continues to traverse the next time slot node. Repeatedly traverse all time slot nodes until the total number of solid lines connected to each time slot node is reached. The number of solid lines is 0 or connected to a time slot node. If the signal exceeds the multi-packet reception capacity (MR), decoding cannot continue, so the traversal of the bipartite graph is stopped, and decoding is halted.

[0006] The decoding conditions include decoding condition 1, decoding condition 2, and decoding condition 3; Decoding condition 1: If there is no transmission conflict in the time slot where the data packet copy is located, that is, there is only one data packet copy in the time slot, and that is, there is only one sending end node connected to the current time slot node. Decoding condition 2: If the total number of data packet replicas in the time slot where the data packet replica is located is... Less than or equal to the multi-packet reception capacity (MR), meaning the number of transmitting nodes connected to the current timeslot node is within the multi-packet reception capacity. Decoding condition 3: If the total number of data packet replicas in the time slot where the data packet replica is located is... The maximum number of packets that can be received (MR) is greater than the multi-packet reception capacity, but all copies of packets exceeding the MR can be recovered or successfully decoded. This means the current time slot node has multiple lines connected to the sending node, but at most only one... The solid line connects to the time slot node.

[0007] The beneficial effects of this invention are as follows: By employing multi-packet reception (MR) capability, the decoding threshold is relaxed from "no collision" to "collision count ≤ MR". This allows collision slots, which in traditional protocols required iterative interference elimination, to be directly resolved in the first iteration. This proactive utilization of collision slots directly increases the system's actual peak throughput and significantly improves channel congestion under high load. Secondly, it significantly reduces data transmission latency and computational overhead. Because MR capability provides the receiver with stronger initial decoding potential, the system no longer relies solely on a lengthy iterative interference elimination process to recover data packets. Under the same packet loss rate requirement, the number of iterations required by this scheme is greatly reduced, not only shortening the latency from signal reception to data decoding but also reducing the computational complexity on the base station side, which is of great significance for mMTC applications with high real-time requirements. Attached Figure Description

[0008] Figure 1 The figure shown is a system model diagram of an irregular repetitive time slot ALOHA protocol method based on multi-packet reception provided by the present invention; Figure 2 The diagram shown is a schematic of the MR-IRSA transmitter provided by the present invention; Figure 3 The diagram shown is a diagram illustrating the initial and final states of the iterative interference elimination process provided by this invention. Figure 4 The diagram shown is a schematic of the iterative interference elimination process provided by the present invention; Figure 5 The diagram shows the relationship between the unknown probability of data packets and the channel load provided by the present invention; (a) is the unknown probability curve of data packets when the channel load is equal to 3; (b) is the unknown probability curve of data packets when the channel load is equal to 3.5. Figure 6 The figure shown is a graph illustrating the relationship between multi-packet reception capability and channel load threshold provided by this invention. Figure 7 The figure shown is a graph showing the relationship between multi-packet reception capability and normalized throughput provided by the present invention; (a) is a graph showing the degree distribution of terminal nodes. (a) The relationship between multi-packet reception capability and normalized throughput; (b) Taking the degree distribution of terminal nodes. The relationship between multi-packet reception capability and normalized throughput; Figure 8 The figure shown is a graph illustrating the relationship between multi-packet receiving capability and packet loss rate provided by this invention. Figure 9 The figure shown is a graph illustrating the relationship between packet error rate and normalized throughput provided by this invention. Figure 10 The figure shows the relationship between the number of time slots and the normalized throughput provided by the present invention; (a) is the normalized throughput curve when the number of time slots is 50; (b) is the normalized throughput curve when the number of time slots is 100; (c) is the normalized throughput curve when the number of time slots is 200; and (d) is the normalized throughput curve when the number of time slots is 1000. Detailed Implementation

[0009] The present invention will be further described below with reference to the accompanying drawings and embodiments. The solution to the technical problem of this invention is an ALOHA protocol method based on multi-packet reception with irregular repetitive time slots, comprising the following steps: S1: Construct the MR-IRSA system model; The MR-IRSA system model is based on the IRSA protocol model, and adds multi-packet reception capability to the multi-packet reception channel in the IRSA protocol model. MR; The IRSA protocol model includes a transmitter, a selector, a multi-packet reception channel, and a receiver; the scope of the multi-packet reception capability is [missing information]. MR ≥1; S2: Based on the MR-IRSA system model, the sending end sends data packet copies according to a pre-given probability distribution. The sending end sends data packet copies in different time slots, and the sending end sends at most one data packet copy in each time slot; S3: The receiving end receives all data packet copies and decodes the data packet copies; The receiving end receives all data packet copies; based on the received data packet copies, the receiving end constructs a bipartite graph; the bipartite graph includes time slot nodes and terminal nodes; wherein, a time slot node represents all time slots; a terminal node represents the sending end that sends a data packet copy in a time slot node; if the sending end j sends a data packet copy in time slot i, there is an edge connecting time slot node i and sending end node j; if the data packet copy sent by sending end node j in time slot i is successfully decoded, this edge is a dashed line, otherwise it is a solid line; The data packet copy satisfies the decoding requirement if it meets any of the following decoding conditions; The decoding conditions include decoding condition 1, decoding condition 2, and decoding condition 3; Decoding condition 1: If there is no transmission conflict in the time slot where the data packet copy is located, that is, there is only one data packet copy in the time slot, and that is, there is only one sending end node connected to the current time slot node. Decoding condition 2: If the total number of data packet replicas in the time slot where the data packet replica is located is... Less than or equal to the multi-packet reception capacity (MR), meaning the number of transmitting nodes connected to the current timeslot node is within the multi-packet reception capacity. Decoding condition 3: If the total number of data packet replicas in the time slot where the data packet replica is located is... The maximum number of packets that can be received (MR) is greater than the multi-packet reception capacity, but all copies of packets exceeding the MR can be recovered or successfully decoded. This means the current time slot node has multiple lines connected to the sending node, but at most only one... The solid line connects to the time slot node; Based on the bipartite graph, traverse all time slot nodes; The receiving end receives all data packet copies and constructs a bipartite graph using the received data packet copies. The bipartite graph includes time slot nodes and terminal nodes. A time slot node represents all time slots. A terminal node represents the sending end that sends a data packet copy in a time slot node. If the sending end j sends a data packet copy in time slot i, there is an edge connecting time slot node i and sending end node j. If the data packet copy sent by sending end node j in time slot i is successfully decoded, this edge is a dashed line; otherwise, it is a solid line. Iterate through all time slot nodes in the bipartite graph. For any time slot node, if the number of solid lines connecting it to the time slot node is... If the multi-packet reception capability (MR) is less than or equal to the multi-packet reception capability (MR), then all data packet replicas in the time slot node are decoded. If a data packet replica satisfies any one of the decoding conditions, the decoding is successful. At the same time, the bipartite graph is updated, and all solid lines connecting the time slot nodes are changed to dashed lines. Based on the decoded data packet replica, the sender corresponding to the decoded data packet replica is determined, and the sender corresponding to the decoded data packet replica is marked as successfully decoded. The bipartite graph is updated, and all terminal nodes corresponding to the senders connected to the time slot node are found. All solid lines connecting the terminal nodes corresponding to the senders are changed to dashed lines. If the number of solid lines connected to the time slot node If the received packet count (MR) exceeds the multi-packet reception capacity (MR), decoding is not possible, and the process continues to traverse the next time slot node. Repeatedly traverse all time slot nodes until the total number of solid lines connected to each time slot node is reached. The number of solid lines is 0 or connected to a time slot node. If the signal exceeds the multi-packet reception capacity (MR), decoding cannot continue, so the bipartite graph traversal is stopped and decoding is halted. To facilitate the evaluation of the MR-IRSA system model, the normalized throughput of the MR-IRSA system model is calculated. T N for: T N= ; in, The actual throughput of the system is calculated as follows: ; To facilitate the evaluation of the MR-IRSA system model, the normalized channel load of the MR-IRSA system model is calculated. G N for: G N = ; in, G The actual channel load of the system is calculated as follows: G = ; in, This represents the number of terminal devices that are active and sending data in the current data frame. This represents the total number of time slots contained in the current data frame.

[0010] To facilitate the evaluation of the MR-IRSA system model, the normalized channel load threshold of the MR-IRSA system model is calculated. G * N for: G * N = ; in, This is the channel load threshold; Obtain channel load threshold The steps are as follows: During the traversal of the bipartite graph, define the process of performing the first step... i During the next iteration of the interference cancellation process, the probability that the state of a certain edge associated with a time slot node is unknown is: p i The probability that the state of an edge associated with a terminal node is unknown is: q i It can be seen that the probability that the state of an edge associated with a time slot node is known can be expressed as 1. p i Physically, this means that the probability of a data packet connected to a time slot node at this time not colliding is 1. p i That is, the probability that data packets from all connected terminal nodes can still undergo iterative interference cancellation process is 1, provided that the decoding conditions are met. pi ; For any time slot node, assume it has a common l For a given set of connected edges to be decodeable, a necessary condition is that at least one of the connected edges must have a certain number of edges that can be decoded. l - 1 - MR The state of the edge is already known. Therefore:

[0011] in, p i,l For the first i In the next iteration, the degree is... l The probability that the edge state associated with a time slot node is unknown, and we have: , ; q i,l For the first i In the next iteration, the degree is... l The probability that the edge state associated with the terminal device node is unknown, and we have: , ; Indicates multi-packet receiving capability as The maximum number of edges with unknown states that are allowed when there is an edge connected to the time slot node; k is a loop variable that represents the number of edges with unknown states in the time slot node.

[0012] Then we have:

[0013] Where K is MR, For a certain edge and degree l The probability of time slot node association, Let be the polynomial form of the probability of an edge being associated with a terminal node. for of k The first derivative.

[0014] As a preferred option It can be represented as:

[0015] Therefore, we can obtain:

[0016] but p i and q i They can be represented as:

[0017]

[0018] in, l For a certain edge and degree l The probability of associating with terminal nodes. (x) is in polynomial form; The average number of data packet copies sent to all active terminals.

[0019] As a preferred approach, in real-world communication scenarios, the probability that the state of a certain edge associated with a certain terminal node is unknown... The value of gradually decreases as the iterative interference is eliminated, as expressed by the formula:

[0020] Then we have:

[0021] Further results were obtained:

[0022] It is easy to know that, in At that time, after recursive update The value will decrease.

[0023] As a preferred option, in order to obtain The expression first defines the function. :

[0024] when At that time, it can be concluded that At this point, the following equation holds true:

[0025] Channel load when the above equation holds That is, the channel load threshold. .

[0026] Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It is obvious that the embodiments shown and described in the drawings are merely exemplary, and not all embodiments, and are intended to illustrate the principles and spirit of the invention, and not to limit the scope of the invention.

[0027] like Figure 1 As shown, an irregular repetitive time slot ALOHA protocol method based on multi-packet reception includes the following steps: S1. Based on the MR-IRSA scheme system model, introduce multi-packet reception capability into the multi-packet reception channel. MR ; S2. Based on the MR-IRSA scheme system model, the terminal sends a copy of the data packet according to a pre-given probability distribution. S3. Based on the MR-IRSA scheme system model, design the receiver with multi-packet reception capability. MR An iterative interference elimination scheme.

[0028] In this embodiment, compared with the IRSA scheme, the MR-IRSA scheme system model described in step S1 improves the multi-packet reception capability from 1 to 1 in the multi-packet reception channel. MR ≥1.

[0029] In this embodiment, the decoding condition of the iterative interference cancellation scheme in step S3 is reduced from no data packet collisions occurring in the time slot to the number of data packets in the time slot being less than or equal to... MR .

[0030] In this embodiment, the iterative interference cancellation scheme described in step S3 is represented using a bipartite graph, and includes the following steps: S301. Divide the data packet state into initial state, iterative decoding state, and final state; S302. A bipartite graph consists of time slot nodes, terminal nodes, and edges connecting the two. S303. Edges that have been successfully decoded are represented by dashed lines, while edges that have not yet been successfully decoded are represented by solid lines.

[0031] In this embodiment, a specific example is used to illustrate the iterative elimination process: A schematic diagram of the MR-IRSA transmitter is shown below. Figure 2 As shown in the figure. Among them, terminals A, B, C, and D send 2 copies of the data packets, while terminals E and F send 3 copies of the data packets.

[0032] In this embodiment, Figure 2 The initial and final states of the corresponding iterative interference cancellation process are as follows: Figure 3 As shown in the diagram, terminals A, B, and C send data packets 1A, 2A, 1B, 2B, 1C, and 2C in time slots 1 and 2, respectively; terminal D sends data packets 1D and 2D in time slots 1 and 3; terminal E sends data packets 1E, 2E, and 3E in time slots 1, 2, and 3; and terminal F sends data packets 1F, 2F, and 3F in time slots 1, 3, and 4.

[0033] In this embodiment, Figure 2 The corresponding specific iterative interference elimination process is as follows: Figure 4 As shown, the multi-packet receiving capability MR = 2. Specifically, it includes the following steps: S401. Initialize the in-degree of the time slot nodes, i.e., the number of solid lines connecting the time slot nodes are 6, 4, 3, and 1 respectively. The in-degree of the current time slot node 4 is 1, where 1 ≤ 1. MR = 2, therefore time slot node 4 meets the condition, and recovery starts from time slot node 4; S402. The only terminal node associated with time slot node 4 is terminal node F, and the other replica data packets of F are also successfully decoded; S403. During the second decoding process, the in-degree of the time slot node becomes 5, 4, 2, 0. Time slot node 3 meets the decoding conditions, that is, terminal nodes D and E are successfully decoded, and the related data packet interference is removed. S404. During the third decoding process, the in-degree of the time slot node is 3, 3, 0, 0. There is no time slot node that meets the decoding requirements, and the iterative interference elimination process ends here.

[0034] In this embodiment, the normalized throughput of the MR-IRSA scheme is defined. T N Normalized channel load G N and normalized channel load threshold G * N .

[0035] Specifically, T N , G N , G * N They are respectively: T N = ; G N = ; G * N = ; in, T For the actual throughput of the system, G For the actual channel load of the system, G * This represents the actual channel load threshold of the system. MR This is for multi-packet receiving capability.

[0036] In this embodiment, the actual throughput of the system T The calculation formula is:

[0037] in, Figure 1 In the corresponding iterative interference cancellation process, the number of successfully decoded data packets is 3 (F, D, E), and the total number of time slots is 4. Therefore: T = 3 / 4 = 0.75; T N = T / MR = 0.375; In this embodiment, the actual channel load of the system G The calculation formula is: G = M / N in, M This represents the number of terminal devices that are active and sending data in the current data frame. N This represents the total number of time slots contained in the current data frame. Figure 1 The corresponding iterative interference cancellation process, the total number of time slots N = 4, Total number of activated terminals M = 6, therefore: G = 6 / 4 = 1.5 G N = G / MR = 0.75 In this embodiment, in order to calculate the channel load threshold * Analyze the process from the perspective of the edge between the terminal node and the time slot node. i The state of the data packet after the interference is eliminated in the next iteration.

[0038] Specifically, for iterative elimination schemes, the definition is made during the first iteration. i During the next iteration of the interference cancellation process, the probability that the state of a certain edge associated with a time slot node is unknown is: p i The probability that the state of an edge associated with a terminal node is unknown is: q i It can be seen that the probability that the state of an edge associated with a time slot node is known can be expressed as 1. p i Physically, this means that the probability of a data packet connected to a time slot node at this time not colliding is 1. p i That is, the probability that data packets from all connected terminal nodes can still undergo iterative interference cancellation process is 1, provided that the decoding conditions are met. pi .

[0039] More specifically, for a given time slot node, assuming it has a common... l For a given set of connected edges to be decodeable, a necessary condition is that at least one of the connected edges must have a certain number of edges that can be decoded. l - 1 - MR The state of the edge is already known. Therefore:

[0040] in, p i,l For the first i In the next iteration, the degree is... l The probability that the edge state associated with a time slot node is unknown, and we have: , ; q i,l For the first i In the next iteration, the degree is... l The probability that the edge state associated with the terminal device node is unknown, and we have: , ; Indicates multi-packet receiving capability as The maximum number of edges with unknown states that are allowed when there are l edges connected to the time slot node; k is a loop variable that represents the number of edges with unknown states in the time slot node.

[0041] Then we have:

[0042] Where K is MR, For a certain edge and degree l The probability of time slot node association, Let be the polynomial form of the probability of an edge being associated with a terminal node. for of k The first derivative.

[0043] In this embodiment, It can be represented as:

[0044] Therefore, we can obtain:

[0045] but p i and q i They can be represented as:

[0046]

[0047] in, l For a certain edge and degree l The probability of associating with terminal nodes. (x) is in polynomial form; The average number of data packet copies sent to all active terminals.

[0048] In this embodiment, the probability that the state of a certain edge associated with a certain terminal node is unknown. The value of gradually decreases as the iterative interference is eliminated, as expressed by the formula:

[0049] Then we have:

[0050] Further results were obtained:

[0051] It is easy to know that, in At that time, after recursive update The value will decrease.

[0052] In this embodiment, in order to obtain The expression first defines the function. :

[0053] when At that time, it can be concluded that At this point, the following equation holds true:

[0054] Channel load when the above equation holds That is, the channel load threshold. .

[0055] The invention was verified through simulation. Numerical analysis revealed the relationship between the unknown probability of data packets and the channel load. The results are as follows: Figure 5 As shown. The simulation experiment uses the degree distribution of terminal nodes. Multi-packet receiving capability Number of time slots Channel load Channel load threshold The maximum number of iterations was 200, meaning that sufficient iterative decoding was performed in the simulation to ensure that any decoding failures were not solely due to collisions. Results show that when the channel load is 3, The curve is always located at Below. It can be concluded that... The initial value is always located in the middle of the two lines. After the iteration begins, The value continues to decrease if the number of iterations is unlimited. The value of , i.e., the unknown probability of the edge, will eventually decrease to 0, at which point all packet replicas can be decoded. When the channel load is 3.5, it can be seen that... When the value is in the range of 0.55 to 0.9, the iterated value is... The value will actually increase, indicating that this is different from the case when the channel load is equal to 3. The value cannot converge to 0, so it is impossible to successfully receive all data packets.

[0056] Simulation results of the impact of multi-packet reception capability on the normalized channel load threshold are as follows: Figure 6 As shown. The simulation parameters used in the simulation are... , , The maximum number of iterations is 200, and the number of maximum duplicate data packets corresponding to the terminal node degree distribution are 4 and 8, respectively. Experimental results show that in the MR-IRSA scheme, when the multi-packet reception capability is 2 and 3, the normalized channel load threshold of the system is... It has higher values ​​when multi-packet receiving capability When the value is greater than 3, regardless of the terminal node degree distribution used, The values ​​are all starting to decline, indicating that the multi-packet receiving capability is decreasing. It's not necessarily true that the higher the degree distribution, the better. When the multi-packet reception capability is 1, that is, when the MR-IRSA scheme degenerates into the traditional IRSA scheme, its It only has a value of 0.5, but when multi-packet reception capability is introduced, its... It rose to 0.84 ( (time) and 0.85 ( (At that time), it increased significantly by approximately 68% and 70%. However, for other degree distribution scenarios, although not as... This results in significant improvements, but each improvement is to varying degrees. Even without introducing multi-packet reception capabilities, the performance of these optimal distributions is already high; however, with the introduction of multi-packet reception capabilities, their... This improvement further demonstrates the superiority of the MR-IRSA scheme.

[0057] Simulation results of the impact of multi-packet reception capability on normalized throughput are as follows: Figure 7 As shown. The simulation parameters used in the simulation are... , , The maximum number of iterations is 200, and the number of maximum duplicate data packets corresponding to the terminal node degree distribution are 4 and 8, respectively. Experimental results show that, when approaching the channel load threshold, the throughput performance of the scheme with multi-packet reception capability is greater than that of the scheme without multi-packet reception capability (i.e., ),in, The performance of the scheme is the best. However, when the channel load exceeds the channel load threshold, the increased channel load leads to more data packets in the channel due to the introduction of multi-packet reception capability. Even with stronger decoding capabilities, these capabilities cannot be effectively utilized, meaning collisions cannot be resolved. Therefore, simulation results show that the performance of the scheme with multi-packet reception capability degrades when the channel load exceeds the threshold, especially when the multi-packet reception capability is at its maximum, where the degradation is greater. This demonstrates that a higher multi-packet reception capability is not always better. The actual simulation results of this scheme show that when… The overall performance is best when the multi-packet reception capability is at its optimal level. In real-world communication scenarios, improving multi-packet reception capability often requires additional costs, and the cost tends to increase even more as the multi-packet reception capability improves. Therefore, a comprehensive consideration is necessary in practical implementation.

[0058] Simulation results of the impact of multi-packet reception capability on system packet loss rate are as follows: Figure 8 As shown. The simulation parameters used in the simulation are... , , The maximum number of iterations was 200. Experimental results show that under most channel loads, the packet loss rate decreases as the multi-packet receiving capability increases. The slope of the curve indicates that the larger the multi-packet receiving capability, the greater its impact on the packet loss rate. A larger multi-packet receiving capability results in more actual data packets under the same normalized channel load. When the normalized channel load approaches the normalized channel load threshold, data packets begin to congest, decoding capability is limited, and therefore the packet loss rate begins to rise rapidly. When the normalized channel load exceeds the normalized channel load threshold, the packet loss rate approaches 1, indicating that as the normalized channel load exceeds the threshold, the system's ability to transmit data packets decreases significantly, and the system cannot handle collisions. This is consistent with previous simulation results.

[0059] Simulation results of the impact of packet error rate on system throughput are as follows: Figure 9 As shown. The simulation parameters used in the simulation are... , Packet error rate The maximum number of iterations is 200. Simulation results show that when the normalized channel load is less than the normalized channel load threshold, the packet error rate (BER) has almost no impact on throughput when it is 0.01 or 0.05. When the BER is 0.1, the throughput performance decreases slightly, but the decrease is very small. When the normalized channel load is equal to 0.6, the normalized throughput decreases by only 0.01. The results show that when the normalized channel load is higher than the threshold, the system's decoding capability begins to gradually decrease. However, the packet loss caused by the BER actually reduces the probability of conflicting transmissions to some extent, alleviating channel congestion and slightly improving the system's throughput performance. Overall, when the BER is within a reasonable range, the change in the system's normalized throughput is not particularly large, which is similar to actual communication scenarios and also demonstrates the robustness of the MR-IRSA scheme.

[0060] Simulation results of the impact of the number of time slots on system throughput are as follows: Figure 10 As shown. The parameters used in the simulation are... , , , The maximum number of iterations is 200. Simulation results show that when the number of time slots is 1000, the peak normalized throughput reaches approximately 0.85, an improvement of about 19.5% compared to 50 time slots, and an improvement of about 13% compared to 100 time slots. This indicates that as the number of time slots increases, the system performance gradually improves, approaching the theoretical performance of the system. Furthermore, the simulation results also clearly show that as the number of time slots increases, the channel load corresponding to the peak normalized throughput point gets closer and closer to the channel load threshold point, which is consistent with the previous analysis of the channel load threshold point. However, in actual systems, increasing the number of time slots is often accompanied by other limitations, such as technical and energy consumption constraints, similar to the optimization process of terminal node degree distribution. Therefore, in practice, it is often necessary to consider multiple factors when setting the number of time slots in each frame.

Claims

1. A method for the irregular repetitive time slot ALOHA protocol based on multi-packet reception, characterized in that, Includes the following steps: S1: Construct the MR-IRSA system model; The MR-IRSA system model is based on the IRSA protocol model, and adds multi-packet reception capability to the multi-packet reception channel in the IRSA protocol model. MR; S2: Based on the MR-IRSA system model, the sending end sends data packet copies according to a pre-given probability distribution. The sending end sends data packet copies in different time slots, and the sending end sends at most one data packet copy in each time slot; S3: The receiving end receives all data packet copies and constructs a bipartite graph using the received data packet copies; the bipartite graph includes time slot nodes and terminal nodes; wherein, a time slot node represents all time slots; a terminal node represents the sending end that sends a data packet copy in a time slot node; if the sending end j sends a data packet copy in time slot i, there is an edge connecting time slot node i and sending end node j; if the data packet copy sent by sending end node j in time slot i is successfully decoded, this edge is a dashed line, otherwise it is a solid line; Iterate through all time slot nodes in the bipartite graph. For any time slot node, if the number of solid lines connecting it to the time slot node is... If the multi-packet reception capability (MR) is less than or equal to the multi-packet reception capability (MR), then all data packet replicas in the time slot node are decoded. If a data packet replica satisfies any one of the decoding conditions, the decoding is successful. At the same time, the bipartite graph is updated, and all solid lines connecting the time slot nodes are changed to dashed lines. Based on the decoded data packet replica, the sender corresponding to the decoded data packet replica is determined, and the sender corresponding to the decoded data packet replica is marked as successfully decoded. The bipartite graph is updated, and all terminal nodes corresponding to the senders connected to the time slot node are found. All solid lines connecting the terminal nodes corresponding to the senders are changed to dashed lines. If the number of solid lines connected to the time slot node If the received packet count (MR) exceeds the multi-packet reception capacity (MR), decoding is not possible, and the process continues to traverse the next time slot node. Repeatedly traverse all time slot nodes until the total number of solid lines connected to each time slot node is reached. The number of solid lines is 0 or connected to a time slot node. If the signal exceeds the multi-packet reception capacity (MR), decoding cannot continue, and the traversal of the bipartite graph is stopped.

2. The ALOHA protocol method based on multi-packet reception with irregular repetitive time slots according to claim 1, characterized in that, The decoding conditions include decoding condition 1, decoding condition 2, and decoding condition 3; The decoding condition 1 is that if there is no transmission conflict in the time slot where the data packet copy is located, that is, there is only one data packet copy in the time slot, which means that there is only one sending end node connected to the current time slot node. The decoding condition 2 is if the total number of data packet replicas in the time slot where the data packet replica is located is... Less than or equal to the multi-packet reception capacity (MR), meaning the number of transmitting nodes connected to the current timeslot node is within the multi-packet reception capacity. The decoding condition 3 is if the total number of data packet replicas in the time slot where the data packet replica is located is... The maximum number of packets that can be received (MR) is greater than the multi-packet reception capacity, but all copies of packets exceeding the MR can be recovered or successfully decoded. This means the current time slot node has multiple lines connected to the sending node, but at most only one... The solid line connects to the time slot node.

3. The ALOHA protocol method based on multi-packet reception with irregular repetitive time slots according to claim 1, characterized in that, The range of the multi-packet receiving capability is: MR ≥1.

4. A storage medium, characterized in that, It stores a computer program that, when executed by a processor, implements the steps of the ALOHA protocol method based on multi-packet reception with irregular repeating time slots as described in any one of claims 1-3.

5. A terminal device, comprising a processor, a memory, and a computer program stored in the memory; characterized in that, When the processor executes a computer program, it implements the steps of the irregular repetitive time slot ALOHA protocol method based on multi-packet reception as described in any one of claims 1-3.

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