Protocol method for irregular repetitive time slot aloha based on terminal priority

Abstract

The application provides a protocol method of an irregular repeated time slot ALOHA based on terminal priority, and mainly solves the problems of throughput performance decline and low throughput performance of IRSA protocol and PR-ALOHA under high channel load; the scheme steps of the application are as follows: based on the IRSA protocol, an access controller is added to construct a P-IRSA scheme system model framework; the application constructs a new P-IRSA scheme, retains the original high performance of the IRSA scheme on the basis of the IRSA protocol, adds the access controller which influences the access probability of terminal equipment, and gives different access probabilities to terminal equipment with different priorities according to the estimated value of the current channel load. The actual experiment for verifying the scheme shows the superiority of the scheme.

Description

Technical Field

[0001] The invention belongs to the technical field of wireless communications, and in particular relates to a protocol method of irregularly repeated time slot ALOHA based on terminal priority. Background Art

[0002] With the continuous development of the economy and society, communication scenarios and user needs are becoming increasingly diverse, and the communication needs of massive machine-type devices have become an urgent problem that needs to be addressed. Traditional random access strategies based on resource allocation are insufficient to cope with massive machine-type communication scenarios where the number of terminals changes frequently and short burst packets are predominant. Therefore, researchers have begun to refocus on the contention-based ALOHA and its derivative machine protocols proposed in the last century. In particular, the performance of these protocols has been significantly improved after the introduction of iterative interference cancellation technology. For example, the contention-removing diversity slotted ALOHA (CRDSA) and iterative random subset assignment (IRSA) protocols, by optimizing the number of packet copies and introducing iterative interference cancellation technology, not only improve throughput performance but also significantly reduce the probability of collisions.

[0003] However, despite its excellent theoretical throughput, the IRSA protocol does not fully consider user Quality of Service (QoS) requirements. This can lead to a degradation in the QoS of some services, particularly when channel load exceeds a threshold. Among the vast majority of machine-to-machine communications, a significant portion of scenarios, such as those requiring regular updates of system and location information, do not require high real-time performance. Conversely, many scenarios involve system security, payment, and other requirements, which require higher access priority. This means that when channel packet collisions are unavoidable, communication needs in these scenarios should be met as much as possible. To address this issue, the PR-ALHOA protocol reserves specific time slots in data frames for high-priority services, classifying traffic as either low-priority or high-priority to address different scenarios. PR-ALHOA effectively addresses the communication challenges of high-priority scenarios without compromising overall throughput. However, its throughput performance is inferior to IRSA, and channel resource utilization still requires improvement. Summary of the Invention

[0004] In order to overcome the shortcomings of the existing technology and solve the problems of reduced throughput performance of the existing IRSA protocol under high channel load and low throughput performance of the PR-ALOHA protocol, the present invention proposes a protocol method of irregular repetitive time slot ALOHA based on terminal priority.

[0005] A protocol method for irregularly repetitive time slot ALOHA based on terminal priority includes a P-IRSA system framework model; the P-IRSA system framework model is an IRSA protocol model with an access controller added; the IRSA protocol model includes a terminal, a selector, a receiving channel and a receiving end; the access controller includes an access control adaptation method and a system channel load estimation method; the access control adaptation method calculates the system channel load according to the system channel load estimation method, multiplies the calculated access probability of a terminal with a priority of k by a random number between 0 and 1, and if the multiplied result is less than the access probability of the terminal with the priority of k, the terminal is allowed to access; if the multiplied result is greater than or equal to the access probability of the terminal with the priority of k, the access is denied; if the terminal is allowed to access, the selector uses the degree distribution of the predefined terminal to determine the number of data packet copies, and according to the number of data packet copies, the terminal will send the data packet copies in different time slots; if the terminal is denied access, the access request of the next terminal is processed.

[0006] Furthermore, the steps of the access control adaptive method are:

[0007] S1-101: Define the priority of the terminal according to the terminal type;

[0008] S1-102: Define the constraints of the P-IRSA system framework model:

[0009] The constraints of the P-IRSA system framework model are the simulation channel load threshold The probability that the channel load threshold G * , the constraint expression is:

[0010]

[0011] 0≤p ac (k)≤1,k=1,2,…,L;

[0012] Among them, P user (k) is the ratio of the number of terminals with priority k to the number of all terminals; p ac (k) is the access probability of the terminal with priority k; is the simulation channel load threshold, G is the system channel load; L is the number of terminal priorities;

[0013] S1-103: Define the system channel load turning point P(k). The system channel load turning point is used to adjust the access probability of terminals with different priorities. The number of channel load turning points P(k) is the same as the number of terminal priorities.

[0014] The expression formula of the system channel load turning point P(k) is:

[0015]

[0016] Among them, P user (i) is the ratio of the number of terminals with priority i to the number of all terminals; is the simulation channel load threshold;

[0017] S1-104: Calculate access probabilities of terminals with different priorities;

[0018] Calculate the system channel load and, based on the system channel load, calculate the access probability of terminals of different priorities.

[0019] Furthermore, the steps of the system channel load estimation method are:

[0020] Step 1: Calculate the number of time slots N in each frame where no terminal is connected to any time slot in the frame I :

[0021]

[0022] Where n is the number of time slots; m is the number of terminals in the current channel; Λ'(1) is the average number of data packet copies sent by all active terminals;

[0023] Step 2: Calculate the number of terminals in the current channel and obtain the estimated channel load G;

[0024] By calculating the number of terminals in the current channel, the estimated channel load G is:

[0025]

[0026] Where n represents the number of time slots; N I represents the number of time slots in each frame with no terminal connected to it; Λ'(1) represents the average number of data packet copies sent by all active terminals.

[0027] Furthermore, the system channel load includes four situations, specifically:

[0028] a. When the system channel load is less than or equal to the first turning point;

[0029] b. When the system channel load is greater than the first system channel load turning point, and the system channel load is less than or equal to the second system channel load turning point;

[0030] c. When the system channel load is greater than the ω-th system channel load turning point, and the system channel load is less than or equal to the ω+1-th system channel load turning point;

[0031] d. The system channel load is greater than the Lth system channel load turning point.

[0032] Furthermore, the step of calculating the access probability of terminals of different priorities is:

[0033] When the system channel load is case a, the following conditions apply:

[0034] G≤P(1);

[0035]

[0036] Where G is the system channel load; P(1) represents the load turning point of the first channel; P user (k) is the ratio of the number of terminals with priority k to the number of all terminals; L is the number of different terminal priorities;

[0037] At this time, the channel load has not yet reached the first turning point. When all terminals do not perform access control, the maximum throughput is achieved, that is:

[0038] p ac (k)=1,k=1,2,...,L;

[0039] Among them, p ac (k) is the access probability of the terminal with priority k; L is the number of different terminal priorities;

[0040] When the system channel load is case b, there are conditions: P(1) <G≤P(2);

[0041] Where G is the system channel load; P(1) represents the load turning point of the first channel; P(2) represents the load turning point of the second channel;

[0042] At this time, the channel load is between the first channel load turning point and the second channel load turning point. ac When (k)=1,k=1,2,...,L,we have:

[0043]

[0044] Among them, P user (k) is the ratio of the number of terminals with priority k to the number of all terminals; is the simulation channel load threshold, G is the system channel load;

[0045] When the system channel load exceeds the critical point, the throughput will be reduced, thus limiting the access probability of low-priority terminals. According to the constraints of the P-IRSA system framework model, there is a formula:

[0046]

[0047] Among them, P user (k) is the ratio of the number of terminals with priority k to the number of all terminals; p ac (k) is the access probability of the terminal with priority k; is the simulation channel load threshold, G is the system channel load, and L is the number of different terminal priorities;

[0048] In order to obtain the maximum throughput and ensure the transmission of high-priority terminals, the access probability p of terminals with different priorities is ac (k) is set to:

[0049]

[0050] Among them, P user (i) is the ratio of the number of terminals with priority i to the number of all terminals; p ac (k) is the access probability of the terminal with priority k; is the simulation channel load threshold, G is the system channel load, and L is the number of different terminal priorities;

[0051] When the system channel load is case c, the following conditions apply:

[0052] P(ω) <G≤P(ω+1),ω=2,3,...,L-1;

[0053] Where G is the system channel load; P(ω) represents the load turning point of the ωth channel; P(ω+1) represents the load turning point of the ω+1th system channel;

[0054] At this time, when p ac When (k)=1, k=1,2,...,L, we have the following formula:

[0055]

[0056] Among them, P user (k) is the ratio of the number of terminals with priority k to all terminals; p ac (k) is the access probability of the terminal with priority k; is the simulation channel load threshold, G is the system channel load, and L is the number of different terminal priorities;

[0057] To achieve maximum throughput and ensure data packet transmission for high-priority terminals, the access probability of high-priority terminals is set to 1 and the access probability of low-priority terminals is set to 0. The formula is:

[0058]

[0059] Among them, Puser (k) is the ratio of the number of terminals with priority k to all terminals; p ac (k) is the access probability of the terminal with priority k; is the simulation channel load threshold, G is the system channel load, and L is the number of different terminal priorities;

[0060] In order to obtain the maximum throughput and ensure the transmission of high-priority terminals, the access probability p of terminals with different priorities is ac (k) is set to:

[0061]

[0062] Among them, P user (i) is the ratio of the number of terminals with priority i to the number of all terminals; p ac (k) is the access probability of the terminal with priority k; is the simulation channel load threshold, G is the system channel load, L is the number of different terminal priorities, and ω is the ωth channel;

[0063] When the system channel load is case d, the following conditions apply:

[0064] G>P(L);

[0065] Where G is the system channel load; P(L) represents the load turning point of the ωth channel;

[0066] At this time, only the terminal with the highest priority can access the channel, p ac (k) is set to:

[0067]

[0068] Among them, P user (1) is the ratio of the number of terminals with priority 1 to the number of all terminals; p ac (k) is the access probability of the terminal with priority k; is the simulation channel load threshold, G is the system channel load, and L is the number of different terminal priorities.

[0069] The present invention has the following beneficial effects: The P-IRSA scheme significantly reduces packet loss and improves throughput under high channel loads compared to the IRSA scheme. Furthermore, the proposed channel load estimate closely matches the actual channel load, ensuring the quality of service for critical services under high-load conditions. Under high channel load conditions, the communication needs of high-priority terminal devices are prioritized, thereby ensuring the quality of service for critical services. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1The flowchart of the design of irregular repetitive time slot ALOHA protocol method based on terminal priority;

[0071] Figure 2 The simulation results of packet loss rate of different schemes as the channel load G changes;

[0072] Figure 3 The simulation results of throughput of different schemes as the channel load G changes. DETAILED DESCRIPTION

[0073] A protocol method for irregularly repeated time slot ALOHA based on terminal priority, comprising the following steps:

[0074] S1: Based on the IRSA protocol, construct the P-IRSA system framework model;

[0075] The IRSA protocol model includes a terminal, a selector, a receiving channel and a receiving end;

[0076] The P-IRSA system framework model is to add an access controller on the basis of the IRSA protocol;

[0077] After receiving the terminal access request, the access controller determines whether the terminal is allowed to access based on the terminal priority and channel load;

[0078] If the terminal is allowed to access, the selector uses the degree distribution of the predefined terminals to decide the number of packet copies. According to the number of packet copies, the terminal will send packet copies in different time slots.

[0079] If the terminal access is denied, the access request of the next terminal will be processed;

[0080] The access control module gives different terminals different access probabilities according to terminal priority and channel load, so that when the channel load is greater than the channel load threshold, high-priority terminals enjoy a higher access probability;

[0081] The access controller includes an access control adaptive method and a system channel load estimation method; the access control adaptive method multiplies the access probability of a terminal with a priority of k calculated based on the system channel load by a random number between 0 and 1, and allows the terminal access if the result of the multiplication is less than the access probability of the terminal with the priority of k; otherwise, the access is denied;

[0082] The access controller prioritizes the communication needs of high-priority terminal devices under high channel load conditions, thereby ensuring the service quality of key services;

[0083] The steps of designing the access control adaptive method by the access controller are as follows:

[0084] S201: defining the priority of the terminal according to the type of the terminal;

[0085] S202: Define the constraints of the P-IRSA system framework model:

[0086] The constraints of the P-IRSA system framework model are the simulation channel load threshold The probability that the channel load threshold G * , the constraint condition makes the packet loss rate within the acceptable range, ensuring the traffic of high-priority terminals. When the traffic load exceeds the critical point, the access of low-priority devices is reduced. The expression of the constraint condition is:

[0087]

[0088] 0≤p ac (k)≤1,k=1,2,…,L;

[0089] Among them, P user (k) is the ratio of the number of terminals with priority k to the number of all terminals; p ac (k) is the access probability of the terminal with priority k; is the simulation channel load threshold, G is the system channel load; L is the number of terminal priorities;

[0090] S203: defining a system channel load turning point P(k), which is used to adjust the access probability of terminals with different priorities; the number of channel load turning points P(k) is the same as the number of terminal priorities;

[0091] The expression formula of the system channel load turning point P(k) is:

[0092]

[0093] Among them, P user (i) is the ratio of the number of terminals with priority i to the number of all terminals; is the simulation channel load threshold;

[0094] S204: Calculate the access probability of the terminal;

[0095] Based on the system channel load, the access probability of the terminal is calculated in four cases:

[0096] a. When the system channel load is less than or equal to the first turning point;

[0097] b. When the system channel load is greater than the first system channel load turning point, and the system channel load is less than or equal to the second system channel load turning point;

[0098] c. When the system channel load is greater than the ω-th system channel load turning point, and the system channel load is less than or equal to the ω+1-th system channel load turning point;

[0099] d. The system channel load is greater than the Lth system channel load turning point;

[0100] When the system channel load is case a, the following conditions apply:

[0101] G≤P(1);

[0102]

[0103] Where G is the system channel load; P(1) represents the load turning point of the first channel; P user (k) is the ratio of the number of terminals with priority k to the number of all terminals; p ac (k) is the access probability; L is the number of different terminal priorities;

[0104] At this time, the channel load has not yet reached the first turning point. When all terminals do not perform access control, the maximum throughput is achieved, that is:

[0105] p ac (k)=1,k=1,2,...,L;

[0106] Among them, p ac (k) is the access probability; L is the number of different terminal priorities;

[0107] When the system channel load is case b, the following conditions apply:

[0108] P(1) <G≤P(2);

[0109] Where G is the system channel load; P(1) represents the load turning point of the first channel; P(2) represents the load turning point of the second channel;

[0110] At this time, the channel load is between the first channel load turning point and the second channel load turning point. ac When (k)=1,k=1,2,...,L,we have:

[0111]

[0112]

[0113] Among them, P user (k) is the ratio of the number of terminals with priority k to the number of all terminals; is the simulation channel load threshold, G is the system channel load;

[0114] When the system channel load exceeds the critical point, the throughput will be reduced, thus limiting the access probability of low-priority terminals. According to the constraints of the P-IRSA system framework model, the following formula is obtained:

[0115]

[0116] Among them, P user (k) is the ratio of the number of terminals with priority k to the number of all terminals; p ac (k) is the access probability of the terminal with priority k; is the simulation channel load threshold, G is the system channel load, and L is the number of different terminal priorities;

[0117] In order to obtain the maximum throughput and ensure the transmission of high-priority terminals, the access probability of terminals of different priorities is set as follows:

[0118]

[0119] Among them, P user (i) is the ratio of the number of terminals with priority i to the number of all terminals; p ac (k) is the access probability of the terminal with priority k; is the simulation channel load threshold, G is the system channel load, and L is the number of different terminal priorities;

[0120] When the system channel load is case c, the following conditions apply:

[0121] P(ω) <G≤P(ω+1),ω=2,3,...,L-1;

[0122] Where G is the system channel load; P(ω) represents the load turning point of the ωth channel; P(ω+1) represents the load turning point of the ω+1th system channel;

[0123] At this time, when p ac When (k)=1, k=1,2,...,L, we have the following formula:

[0124]

[0125] Among them, P user (k) is the ratio of the number of terminals with priority k to all terminals; p ac (k) is the access probability of the terminal with priority k; is the simulation channel load threshold, G is the system channel load, and L is the number of different terminal priorities;

[0126] To achieve maximum throughput and ensure data packet transmission for high-priority terminals, the access probability of high-priority terminals is set to 1 and the access probability of low-priority terminals is set to 0. The following formula is used:

[0127]

[0128] Among them, P user (k) is the ratio of the number of terminals with priority k to all terminals; p ac (k) is the access probability of the terminal with priority k; is the simulation channel load threshold, G is the system channel load, and L is the number of different terminal priorities;

[0129] In order to obtain the maximum throughput and ensure the transmission of high-priority terminals, the access probability of terminals of different priorities is set as follows:

[0130]

[0131] Among them, P user (i) is the ratio of the number of terminals with priority i to the number of all terminals; p ac (k) is the access probability of the terminal with priority k; is the simulation channel load threshold, G is the system channel load, L is the number of different terminal priorities, and ω is the ωth channel;

[0132] When the system channel load is case d, the following conditions apply:

[0133] G>P(L);

[0134] Where G is the system channel load; P(L) represents the load turning point of the ωth channel;

[0135] At this point, only the highest priority terminal can access the channel, and the access probability is set as follows:

[0136]

[0137] Among them, P user (1) is the ratio of the number of terminals with priority 1 to the number of all terminals; p ac (k) is the access probability of the terminal with priority k; is the simulation channel load threshold, G is the system channel load, and L is the number of different terminal priorities;

[0138] The access controller designs an adaptive access control method that divides terminals into multiple priority levels and dynamically adjusts the access probability of terminals of each priority level according to the channel load. This can effectively control the number of data packets in the channel and avoid an increase in packet loss rate and a decrease in throughput caused by channel overload.

[0139] The estimation method of the system channel load G is:

[0140] Step 1: The number of time slots in each frame where no terminal is connected to any time slot in the frame is N I :

[0141]

[0142] Where n is the number of time slots; m is the number of terminals in the current channel; Λ'(1) is the average number of data packet copies sent by all active terminals;

[0143] Step 2: Calculate the number of terminals in the current channel and obtain the estimated channel load G;

[0144] In this embodiment, the estimated channel load G obtained by calculating the number of terminals on the current channel is expressed as follows:

[0145]

[0146] Where n represents the number of time slots; N I represents the number of time slots in each frame with no terminal connected to it; Λ'(1) represents the average number of data packet copies sent by all active terminals;

[0147] S3. Based on the P-IRSA system framework model, an iterative elimination scheme is used to evaluate the packet loss rate and throughput of the network system;

[0148] For the iterative elimination scheme, the probability that the state of an edge associated with a time slot node is unknown during the i-th iterative interference elimination process is defined as p i , assuming that the probability that the state of an edge associated with a terminal node is unknown is q i Then, p i and q i Respectively expressed as:

[0149]

[0150] Among them, ρ l represents the probability that an edge is connected to a time slot node with degree l; p i,l represents the probability that the state of the edge connected to a time slot node with degree l is unknown during the i-th iterative interference cancellation process; λ l represents the probability that an edge is connected to a terminal node with degree l; qi,l It represents the probability that the state of the edge connected to a terminal node with degree l is unknown during the i-th iterative interference elimination process.

[0151] In this embodiment, since time slot nodes and terminal nodes require different processing logic when decoding: a terminal node with an in-degree of l only needs to successfully receive any one of l different time slot data packet copies to recover all other copies, while a time slot node with an in-degree of l needs to successfully receive l-1 terminal node data packets to decode the last data packet, thus defining p i,l and q i,l as follows:

[0152] p i,l =1-(1-q i ) l-1 ;

[0153] q i,l =p i-1 i-1 ;

[0154] Among them, p i represents the probability that the state of an edge associated with a time slot node is unknown during the i-th iteration of interference cancellation; q i represents the probability that the state of an edge associated with a terminal node is unknown during the i-th iteration of interference elimination; p i,l represents the probability that the state of the edge connected to a time slot node with degree l is unknown during the i-th iterative interference cancellation process; q i,l It represents the probability that the state of the edge connected to a terminal node with degree l is unknown during the i-th iterative interference elimination process.

[0155] According to the above formula, we can get p i and q i , respectively expressed as the following formulas:

[0156]

[0157] Among them, p i represents the probability that the state of an edge associated with a time slot node is unknown during the i-th iteration of interference cancellation; q i represents the probability that the state of an edge associated with a terminal node is unknown during the i-th iterative interference elimination process; ρ l represents the probability that an edge is connected to a time slot node with degree l; l It represents the probability that an edge is connected to a terminal node with degree l.

[0158] In this embodiment, the derived packet loss rate P L The calculation formula is as follows:

[0159]

[0160] Among them, Λ l represents the probability that the terminal node degree is l; p l It represents the probability that the node degree of a terminal node is l.

[0161] In this embodiment, the derived calculation formula for throughput is as follows:

[0162] T=G(1-P L );

[0163] Where G represents the channel load; P L Indicates the packet loss rate.

[0164] In this embodiment, the channel load threshold G * It is the maximum channel load that the system can converge to so that all data packets can be successfully received. When the channel load is lower than G * When the system converges to a packet loss rate of 0, when the channel load is higher than G * When , it cannot converge to 0, and the channel load satisfies the following expression:

[0165]

[0166] Where Λ'(1) represents the average number of data packet copies sent by all active terminals; G represents the channel load; q i It represents the probability that the state of an edge associated with a terminal node is unknown during the i-th iterative interference elimination process.

[0167] The final channel load threshold G is derived based on mathematical derivation * The expression is as follows:

[0168]

[0169] Among them, G * represents the channel load threshold; Λ'(1) represents the average number of data packet copies sent by all active terminals; λ2 represents the probability that an edge is connected to a terminal node with degree 2.

[0170] The iterative elimination scheme can accurately evaluate the packet loss rate and throughput of the network system through precise iterative elimination scheme design and probability calculation, significantly improving the efficiency and reliability of network transmission.

[0171] The present invention will be further described below with reference to the accompanying drawings and examples.

[0172] The exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be understood that the embodiments shown and described in the accompanying drawings are merely exemplary and are intended to illustrate the principles and spirit of the present invention, rather than to limit the scope of the present invention.

[0173] like Figure 1 As shown, an irregularly repeated time slot ALOHA protocol scheme based on terminal priority includes the following steps:

[0174] S1. Based on the IRSA protocol, a P-IRSA system model framework is constructed, which mainly includes terminals, access controllers, selectors, receiving channels, and receivers.

[0175] S2. Design an adaptive access control scheme at the access controller based on the P-IRSA system model.

[0176] S3. Based on the P-IRSA scheme system model, an iterative elimination scheme is designed at the receiving end;

[0177] In this embodiment, the P-IRSA solution system model framework in step S1 is supplemented with modules for channel load estimation and access control.

[0178] In this embodiment, the access control module is specifically: the terminal device uses the access controller (Access Controller) to limit the number of data packets in the channel before accessing, and the access controller gives different terminal devices different access probabilities according to the terminal device priority and channel load conditions, so as to ensure that when the channel load is greater than the channel load threshold, high-priority terminal devices enjoy a higher access probability.

[0179] In this embodiment, in step S2, the access controller designs an access control adaptive scheme, and the access control adaptive algorithm is specifically:

[0180] S201. The total number of terminals is divided into multiple priority levels;

[0181] S202. Define simulation channel load threshold The probability is slightly less than the system channel load threshold G * , ensure that the packet loss rate is within an acceptable range;

[0182] S203 defines L channel load turning points P (k), used to adjust the access probability of terminals of different priorities;

[0183] S204. Design the access probability of each terminal node under different channel loads.

[0184] In this embodiment, the simulation channel load threshold defined in step S202 is The probability is slightly less than the system channel load threshold G * The expression formula is:

[0185]

[0186] 0≤p ac (k)≤1,k=1,2,…,L;

[0187] Among them, P user (k) is the ratio of terminals with priority k to all terminal devices; p ac (k) is the access probability; is the simulation channel load threshold, and G is the system channel load.

[0188] In this embodiment, the expression formula of the L channel load turning points P(k) defined in step S203 is:

[0189]

[0190] Among them, P user (i) is the ratio of terminals with priority i to all terminal devices; is the simulated channel load threshold.

[0191] In this embodiment, the access probability of each terminal node under different channel loads is designed in step S204 to consider four different situations according to the channel load, specifically:

[0192] a. The channel load has not yet reached the first turning point.

[0193] b. The channel load is between the first channel load turning point and the second channel load turning point.

[0194] c. The channel load is between the ωth channel load turning point and the ω+1th channel load turning point.

[0195] d. The channel load exceeds the Lth channel load turning point.

[0196] In this embodiment, for the above-mentioned situation a, the following conditions apply:

[0197] G≤P(1);

[0198]

[0199] Where G is the system channel load; P(1) represents the load turning point of the first channel; P user (k) is the ratio of terminals with priority k to all terminal devices; p ac (k) is the access probability; L is the number of channels.

[0200] At this point, the channel load has not yet reached the first turning point. When all terminal nodes do not perform access control, the maximum throughput is achieved, that is:

[0201] p ac (k)=1,k=1,2,...,L;

[0202] Among them, p ac (k) is the access probability; L is the number of channels.

[0203] In this embodiment, for the above-mentioned situation b, the following conditions apply:

[0204] P(1) <G≤P(2);

[0205] Where G is the system channel load; P(1) represents the load turning point of the first channel; and P(2) represents the load turning point of the second channel.

[0206] At this time, the channel load is between the first channel load turning point and the second channel load turning point. ac When (k)=1,k=1,2,...,L,we have:

[0207]

[0208] Among them, P user (k) is the ratio of terminals with priority k to all terminal devices; p ac (k) is the access probability; is the simulation channel load threshold, G is the system channel load, and L is the number of channels.

[0209] When the channel load exceeds the critical point, the throughput will be reduced. Therefore, the access probability of low-priority terminals should be limited. According to the probability of the simulated channel load threshold being less than the system channel load threshold, the following formula is obtained:

[0210]

[0211] Among them, P user (k) is the ratio of terminals with priority k to all terminal devices; p ac (k) is the access probability; is the simulation channel load threshold, G is the system channel load, and L is the number of channels.

[0212] In order to obtain the maximum throughput and ensure the transmission of high-priority terminals, the access probability of terminals of different priorities is set as follows:

[0213]

[0214] Among them, P user(i) is the ratio of terminals with priority i to all terminal devices; p ac (k) is the access probability; is the simulation channel load threshold, G is the system channel load, and L is the number of channels.

[0215] In this embodiment, for the above-mentioned situation c, the following conditions apply:

[0216] P(ω) <G≤P(ω+1),ω=2,3,...,L-1;

[0217] Where G is the system channel load; P(ω) represents the load turning point of the ωth channel; and P(ω+1) represents the load turning point of the ω+1th channel.

[0218] At this time, when p ac When (k)=1, k=1,2,...,L, we have the following formula:

[0219]

[0220] Among them, P user (k) is the ratio of terminals with priority k to all terminal devices; p ac (k) is the access probability; is the simulation channel load threshold, G is the system channel load, and L is the number of channels.

[0221] To achieve maximum throughput and ensure data packet transmission for high-priority terminals, the access probability of high-priority terminals is set to 1 and the access probability of low-priority terminals is set to 0. The following formula is used:

[0222]

[0223] Among them, P user (k) is the ratio of terminals with priority k to all terminal devices; p ac (k) is the access probability; is the simulation channel load threshold, G is the system channel load, and L is the number of channels.

[0224] In order to obtain the maximum throughput and ensure the transmission of high-priority terminals, the access probability of terminals of different priorities is set as follows:

[0225]

[0226] Among them, P user (i) is the ratio of terminals with priority i to all terminal devices; p ac (k) is the access probability; is the simulation channel load threshold, G is the system channel load, L is the number of channels, and ω is the ωth channel.

[0227] In this embodiment, for the above situation d, the following conditions apply:

[0228] G>P(L);

[0229] Where G is the system channel load; P(L) represents the load turning point of the ωth channel.

[0230] At this point, only the highest priority terminal can access the channel, and the access probability is set as follows:

[0231]

[0232] Among them, P user (1) is the ratio of terminals with priority 1 to all terminal devices; p ac (k) is the access probability; is the simulation channel load threshold, G is the system channel load, and L is the number of channels.

[0233] In this embodiment, the method for estimating the channel load required for designing the access probability in step S204 includes defining the number of time slots N in each frame to which no terminal node is connected. I and calculate the number of terminals in the current channel in two steps.

[0234] In this embodiment, the channel load estimation method defines the number of time slots N in each frame to which no terminal node is connected. I The expression is as follows:

[0235]

[0236] Where n is the number of time slots; m is the number of terminals in the current channel; and Λ'(1) is the average number of data packet copies sent by all active terminals.

[0237] In this embodiment, the estimated channel load G' obtained by calculating the number of terminals in the current channel is expressed as follows:

[0238]

[0239] Where n represents the number of time slots; N I represents the number of time slots in each frame with no terminal node connected to it; Λ'(1) represents the average number of data packet copies sent by all active terminals.

[0240] In this embodiment, the simulated channel load threshold is designed to be slightly lower than the system channel load threshold. This ensures that the packet loss rate remains within an acceptable range even when the channel load is high, thereby improving system stability and reliability. Furthermore, by defining multiple channel load turning points and adjusting the access probability based on the different stages of the channel load, it can flexibly respond to communication needs under varying load conditions. In particular, under high load conditions, access is prioritized for high-priority terminals, improving overall system performance and service quality.

[0241] In this embodiment, the iterative elimination scheme designed at the receiving end in step S3 is analyzed using a bipartite graph method, and its performance such as throughput and packet loss rate is derived.

[0242] In this embodiment, for the iterative elimination scheme, the probability that the state of an edge associated with a time slot node is unknown during the i-th iterative interference elimination process is defined as p i , assuming that the probability that the state of an edge associated with a terminal node is unknown is q i Then, p i and q i Respectively expressed as:

[0243]

[0244] Among them, ρ l represents the probability that an edge is connected to a time slot node with degree l; p i,l represents the probability that the state of the edge connected to a time slot node with degree l is unknown during the i-th iterative interference cancellation process; λ l represents the probability that an edge is connected to a terminal node with degree l; q i,l It represents the probability that the state of the edge connected to a terminal node with degree l is unknown during the i-th iterative interference elimination process.

[0245] In this embodiment, since time slot nodes and terminal nodes require different processing logic when decoding: a terminal node with an in-degree of l only needs to successfully receive any one of l different time slot data packet copies to recover all other copies, while a time slot node with an in-degree of l needs to successfully receive l-1 terminal node data packets to decode the last data packet, thus defining p i,l and q i,l as follows:

[0246] p i,l =1-(1-q i ) l-1 ;

[0247] q i,l =p i-1 i-1 ;

[0248] Among them, p i represents the probability that the state of an edge associated with a time slot node is unknown during the i-th iteration of interference cancellation; q i represents the probability that the state of an edge associated with a terminal node is unknown during the i-th iteration of interference elimination; p i,l represents the probability that the state of the edge connected to a time slot node with degree l is unknown during the i-th iterative interference cancellation process; q i,l It represents the probability that the state of the edge connected to a terminal node with degree l is unknown during the i-th iterative interference elimination process.

[0249] According to the above formula, we can get p i and q i , respectively expressed as the following formulas:

[0250]

[0251] Among them, p i represents the probability that the state of an edge associated with a time slot node is unknown during the i-th iteration of interference cancellation; q i represents the probability that the state of an edge associated with a terminal node is unknown during the i-th iterative interference elimination process; ρ l represents the probability that an edge is connected to a time slot node with degree l; l It represents the probability that an edge is connected to a terminal node with degree l.

[0252] In this embodiment, the derived packet loss rate P L The calculation formula is as follows:

[0253]

[0254] Among them, Λ l represents the probability that the terminal node degree is l; p l It represents the probability that the node degree of a terminal node is l.

[0255] In this embodiment, the derived calculation formula for throughput is as follows:

[0256] T=G(1-P L );

[0257] Where G represents the channel load; P L Indicates the packet loss rate.

[0258] In this embodiment, the channel load threshold G * It is the maximum channel load that the system can converge to so that all data packets can be successfully received. When the channel load is lower than G * When the system converges to a packet loss rate of 0, when the channel load is higher than G *When , it cannot converge to 0, and the channel load satisfies the following expression:

[0259]

[0260] Where Λ'(1) represents the average number of data packet copies sent by all active terminals; G represents the channel load; q i It represents the probability that the state of an edge associated with a terminal node is unknown during the i-th iterative interference elimination process.

[0261] The final channel load threshold G is derived based on mathematical derivation * The expression is as follows:

[0262]

[0263] Among them, G * represents the channel load threshold; Λ'(1) represents the average number of data packet copies sent by all active terminals; λ2 represents the probability that an edge is connected to a terminal node with degree 2.

[0264] The present invention is simulated and verified, and the relationship between channel load and data packet status is obtained through numerical analysis. The terminal node degree distribution Λ=0.5x 2 +0.28x 3 +0.22x 8 ,n=200,channel load G=[1,0.938,0.85],channel threshold G * =0.985. The results show that when the channel load G = 0.938 and G = 0.85, the packet unknown probability q decreases significantly after one iteration, indicating that the system can effectively decode and recover packets under these loads. When the channel load G = 1, the packet unknown probability q still decreases in the high range (0.8, 1) but begins to increase in the low range (0, 0.8). This indicates that the high channel load leads to increased packet collisions, causing some packets to enter a deadlock state and be unable to be successfully received or recovered.

[0265] Experimental results demonstrate the practical performance of the proposed channel load estimation method, demonstrating that the estimated channel load closely matches the actual channel load. Comparing the estimated mean and variance under different channel loads reveals that the variance of the estimated value is small under low channel loads and gradually increases with increasing channel load. When the channel load is high, the variance increases significantly, indicating that the estimation accuracy decreases under high loads. The probability density distribution of the estimated channel load when the actual channel load G = 0.5 is plotted experimentally, showing that the distribution approximates a Gaussian distribution, with its mean and variance closely related to the actual channel load.

[0266] like Figure 2 and Figure 3 As shown: The actual simulation experiment used the terminal node degree distribution Λ=0.5x 2 +0.28x 3 +0.22x 8 ,n=200 (maximum number of iterations) When the channel load G is at a high level, the packet loss rate of IRSA approaches 100%, while that of P-IRSA approaches 1%; the actual simulation experiment uses the terminal node degree distribution Λ=0.5x 2 +0.28x 3 +0.22x 8 ,n=200 (maximum number of iterations) When the channel load G is at a high level, the IRSA throughput rate approaches 0%, while the P-IRSA throughput rate approaches 70%.

[0267] Throughput performance analysis shows that the P-IRSA scheme's throughput performance is particularly outstanding under high channel load. Under low channel loads G < 0.5, the throughput of IRSA, AC-CRDSA, and P-IRSA is almost equal to the channel load, with few packet collisions and efficient decoding. As the channel load increases, the throughput of IRSA gradually decreases, especially when G > 0.8, where the throughput drops rapidly, consistent with previous theoretical analysis. AC-CRDSA's throughput performance is relatively stable due to the introduction of an access control mechanism, but its maximum throughput remains around 0.5. P-IRSA, on the other hand, achieves the best throughput performance under high channel loads, particularly in terms of throughput protection for high-priority terminals, where it demonstrates a significant advantage. These results demonstrate that P-IRSA effectively improves the overall system throughput by dynamically adjusting terminal access probabilities.

Claims

1. A protocol method for irregularly repeating slotted ALOHA based on terminal priority, comprising an IRSA protocol model, wherein the IRSA protocol model includes a terminal, a selector, a receiving channel, and a receiving end, and is characterized in that: An access controller is added to the IRSA protocol model to form a P-IRSA system framework model; the access controller includes an access control adaptive method and a system channel load estimation method; the access control adaptive method calculates the system channel load according to the system channel load estimation method, and calculates the priority obtained as The access probability of the terminal is multiplied by a random number between 0 and 1. If the result of the multiplication is less than the priority The access probability of the terminal is allowed to access. If the multiplied result is greater than or equal to the priority If the access probability of the terminal is less than , the terminal access is denied; If the terminal is allowed to access, the selector uses the predefined terminal degree distribution to determine the number of packet copies; the terminal will send packet copies in different time slots according to the number of packet copies; If the terminal access is denied, the access request of the next terminal will be processed; The steps of the access control adaptive method are: S1-101: Define the priority of the terminal according to the terminal type; S1-102: Define the constraints of the P-IRSA system framework model: The constraints of the P-IRSA system framework model are the simulation channel load threshold The probability is less than the system channel load threshold , the constraint expression is: ； ； ； in, The priority is The ratio of the number of terminals to the total number of terminals; The priority is The access probability of the terminal; is the simulation channel load threshold, is the system channel load; is the number of terminal priorities; S1-103: Defining the system channel load turning point , the system channel load turning point is used to adjust the access probability of terminals with different priorities; the channel load turning point The number of is the same as the number of terminal priorities; System channel load turning point The expression formula is: ； in, The priority is The ratio of the number of terminals to the total number of terminals; is the simulation channel load threshold; S1-104: Calculate access probabilities of terminals with different priorities; Calculate the system channel load and, based on the system channel load, calculate the access probability of terminals of different priorities; The system channel load is as follows: a. When the system channel load is less than or equal to the first turning point; b. When the system channel load is greater than the first system channel load turning point, and the system channel load is less than or equal to the second system channel load turning point; c. When the system channel load is greater than The system channel load turning point, and the system channel load is less than or equal to the System channel load turning point; d. System channel load is greater than The system channel load turning point.

2. The method for irregularly repeating time slot ALOHA based on terminal priority according to claim 1, characterized in that: The steps of the system channel load estimation method are: Step 1: Calculate the number of time slots in each frame where no terminal is connected to any time slot in the frame : ； in, Indicates the number of time slots; Indicates the number of terminals in the current channel; Indicates the average number of data packet copies sent by all active terminals; Step 2: Calculate the number of terminals in the current channel and obtain the estimated channel load ; The estimated channel load is obtained by calculating the number of terminals on the current channel for: ； in, Indicates the number of time slots; Indicates the number of time slots in each frame to which no terminal is connected; Indicates the average number of packet copies sent by all active endpoints.

3. The protocol method of irregularly repeated time slot ALOHA based on terminal priority according to claim 1, characterized in that: The steps of calculating the access probabilities of terminals of different priorities are: When the system channel load is case a, the following conditions apply: ； ； in, is the system channel load; It is represented as the load turning point of the first channel; The priority is The ratio of the number of terminals to the total number of terminals; The number of different terminal priorities; At this time, the channel load has not yet reached the first turning point. When all terminals do not perform access control, the maximum throughput is achieved, that is: ； in, The priority is The access probability of the terminal; The number of different terminal priorities; When the system channel load is case b, the following conditions apply: ; in, is the system channel load; It is represented as the load turning point of the first channel; It is represented as the load turning point of the second channel; At this time, the channel load is between the first channel load turning point and the second channel load turning point. When: ； ； in, The priority is The ratio of the number of terminals to the total number of terminals; is the simulation channel load threshold, is the system channel load; When the system channel load exceeds the critical point, the throughput will be reduced, thus limiting the access probability of low-priority terminals. According to the constraints of the P-IRSA system framework model, there is a formula: ； in, The priority is The ratio of the number of terminals to the total number of terminals; The priority is The access probability of the terminal; is the simulation channel load threshold, is the system channel load, The number of different terminal priorities; In order to obtain the maximum throughput and ensure the transmission of high-priority terminals, the access probability of terminals with different priorities is Set to: ； in, The priority is The ratio of the number of terminals to the total number of terminals; The priority is The access probability of the terminal; is the simulation channel load threshold, is the system channel load, The number of different terminal priorities; When the system channel load is case c, the following conditions apply: ； in, is the system channel load; Expressed as The load turning point of each channel; Expressed as Load turning point of each system channel; At this time, when When , we have the following formula: ； ； in, The priority is The ratio of the number of terminals to all terminals; The priority is The access probability of the terminal; is the simulation channel load threshold, is the system channel load, The number of different terminal priorities; To achieve maximum throughput and ensure data packet transmission for high-priority terminals, the access probability of high-priority terminals is set to 1 and the access probability of low-priority terminals is set to 0. The formula is: ； in, The priority is The ratio of the number of terminals to all terminals; The priority is The access probability of the terminal; is the simulation channel load threshold, is the system channel load, The number of different terminal priorities; In order to obtain the maximum throughput and ensure the transmission of high-priority terminals, the access probability of terminals with different priorities is Set to: ； in, The priority is The ratio of the number of terminals to the total number of terminals; The priority is The access probability of the terminal; is the simulation channel load threshold, is the system channel load, is the number of different terminal priorities, For the channels; When the system channel load is case d, the following conditions apply: ； in, is the system channel load; Expressed as The load turning point of each channel; At this time, only the terminal with the highest priority can access the channel. Set to: ； in, is the ratio of the number of terminals with priority 1 to the number of all terminals; The priority is The access probability of the terminal; is the simulation channel load threshold, is the system channel load, The number of different terminal priorities.

4. A computer-readable storage medium storing a computer program, wherein: When the computer program is executed by a processor, the protocol method of irregularly repeated time slot ALOHA based on terminal priority according to any one of claims 1 to 3 is implemented.

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