Time delay sensitive scene-oriented optimization method for authorization-free random access of equipment

Abstract

The invention discloses a time delay sensitive scene-oriented optimization method for authorization-free random access of equipment. The method specifically comprises the following steps of: 1, dividing an emergency random access preamble and a common preamble in a multiple-input-multiple-output system; 2, setting an emergency event module at the transmitting end, authorizing equipment as emergency communication equipment or common equipment through the emergency event module, enabling the emergency communication equipment to obtain an emergency random access lead code use right, and enabling the unauthorized common equipment to use a common lead code; and step 3, dynamically adjusting the distribution proportion of the lead codes and the selection probability of the emergency communication equipment by using a particle swarm optimization algorithm so as to minimize the access time delay of the common equipment and meet the access time delay constraint of the emergency communication equipment, and distributing corresponding access modes and resource scheduling strategies for different emergency event types. According to the method, the equipment access probability can be improved, the access time delay can be reduced, the resource scheduling can be optimized, and the emergency processing capability can be enhanced.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and specifically to an optimization method for unauthorized random access of devices in delay-sensitive scenarios. Background Art

[0002] Multiple-Input Multiple-Output (MIMO) is a technology that is widely used in modern communication systems. By setting up multiple antennas at the transmitting and receiving ends, it can effectively improve the wireless channel capacity, data throughput, enhance signal reliability, and reduce the bit error rate. Unlicensed random access technology refers to the technology that can directly use radio frequency resources without obtaining the right to use the frequency band in advance. Its notable feature is that users can access randomly in idle frequency bands without waiting, which greatly improves the user's access efficiency. Massive machine communication (mMTC), as one of the three common scenarios of 5G networks, has the ability to support a large number of device connections and data transmission, and is very suitable for IoT application scenarios.

[0003] In the current technical field, based on the different characteristics of interpersonal communication and machine communication, technologies have emerged that use non-time slot scheduling-free access methods to achieve unauthorized access. However, in the environment of large-scale machine communication, this access method still needs to be further optimized. Taking the Internet of Things system for port safety detection as an example, there may be thousands of machine devices deployed in the system. In such a scenario, it is necessary to design an adaptive access solution specifically for serving machine communication. The existing machine equipment access solution mainly records device data and then reserves resources to achieve low-latency access. However, in the field of unauthorized random access, since it is impossible to record device data in advance, it is necessary to optimize the access probability based on the access principle. Summary of the invention

[0004] The purpose of the present invention is to provide an optimization method for random access of devices without authorization in delay-sensitive scenarios. The present invention can improve the probability of device access, reduce access delay, optimize resource scheduling and enhance emergency event handling capabilities.

[0005] The technical solution of the present invention is a method for optimizing the random access of devices without authorization in delay-sensitive scenarios, which specifically includes the following steps:

[0006] Step 1: In a multiple-input multiple-output system, an emergency random access preamble and a normal preamble are divided, wherein the emergency random access preamble is used for priority access of emergency communication equipment;

[0007] Step 2: An emergency module is set at the transmitting end, and the emergency module authorizes the device to be an emergency communication device or a common device. The emergency communication device obtains the right to use the emergency random access preamble code, and the unauthorized common device uses the common preamble code;

[0008] Step 3: Use the particle swarm optimization algorithm to dynamically adjust the preamble allocation ratio and the probability of emergency communication device selection to minimize the access delay of ordinary devices and meet the access delay constraint of emergency communication devices, and allocate corresponding access modes and resource scheduling strategies for different emergency event types.

[0009] In the above-mentioned optimization method for random access of devices without authorization in delay-sensitive scenarios, in step 2, setting the emergency module mainly includes the following steps:

[0010] Step 2.1: Set up emergency judgment and secondary protocol. Emergency judgment is the transmitter's judgment on the type of emergency event. The secondary protocol specifies the subsequent procedures between the transmitter and the AP.

[0011] Step 2.2: Setting up the emergency channel. After receiving the random access response, the device terminal adds a secondary protocol to the SRRC connection request according to the emergency judgment to form an SRRC connection request;

[0012] Step 2.3: Set up the secondary protocol establishment request. The access point AP accepts the SRRC connection request and calls resources according to the secondary protocol. After the resource scheduling is completed, SPE is added to the RRC establishment request to form an SRRC establishment request.

[0013] In the aforementioned optimization method for unauthorized random access of devices for delay-sensitive scenarios, in step 2.1, the emergency matter judgment ESA includes a continuous access option, a periodic access option and a single access option; the secondary protocol includes a secondary protocol SP1 corresponding to the continuous access option, SP2 corresponding to the periodic access option and SP3 corresponding to the single access option.

[0014] In the above-mentioned optimization method for random access of devices without authorization in delay-sensitive scenarios, the secondary protocol SP1 refers to the minimum continuous access time required for the transmitter to judge and infer the emergency event and solve the event, and the time is loaded into the secondary protocol and transmitted to the access point AP. After the access point AP receives the secondary protocol, t max is the access delay requirement of EMs, and the duration is changed to t <t max ; When the connection time approaches t, the transmitter sends a request to continue the connection based on the actual situation. When t=t max Or when the sender actively disconnects, the connection is disconnected.

[0015] In the above-mentioned optimized method for license-free random access of devices for delay-sensitive scenarios, the secondary protocol SP2 means that the transmitting end specifies the number of cycles n and the duration T. After the receiving device accepts, it establishes a device-channel-cycle protocol. The access point AP sends an RRC connection request with the transmitting end label every T. And if the information is small, the information can be directly sent together with the RRC connection request, repeating n times; the transmitting end receives the RRC connection request and establishes a connection; when the cycle ends or the transmitting end actively disconnects the connection, the connection is disconnected.

[0016] In the above-mentioned optimized method for license-free random access of devices for delay-sensitive scenarios, the secondary protocol SP3 means that after the SRRC is successfully established, the connection is made using the conventional process.

[0017] In the above-mentioned optimized method for license-free random access of devices for delay-sensitive scenarios, the access delay T C of the ordinary device is calculated as follows:

[0018] T C = T(C+(1-p)E,aN);

[0019] In the formula, C represents the number of ordinary devices, p represents the proportion of selecting the emergency random access preamble, E represents the number of emergency communication devices, a represents the allocation proportion of the preamble, N represents the number of preambles; T(X, Y) represents the access delay, and the calculation formula is:

[0020] T(X,Y) = R(X,Y)*T^;

[0021] In the formula, X represents the number of access devices, Y represents the number of preambles used, R(X, Y) represents the average number of random access opportunities, and T^ represents the duration of the random access opportunity;

[0022] The calculation formula for the average number of random access opportunities R(X, Y) is expressed as:

[0023]

[0024] In the formula, i represents the number of currently accessing devices, and k represents the number of antennas.

[0025] In the above-mentioned optimized method for license-free random access of devices for delay-sensitive scenarios, the access delay T E of the emergency communication device is calculated as follows:

[0026]

[0027] Wherein, C represents the number of ordinary devices, p represents the proportion of selecting emergency random access preambles, E represents the number of emergency communication devices, a represents the allocation proportion of preambles, N represents the number of preambles; T(X, Y) represents the access delay, and the calculation formula is:

[0028] T(X, Y) = R(X, y) * T^;

[0029] Wherein, X represents the number of access devices, Y represents the number of preambles used, R(X, Y) represents the average number of random access opportunities, and T^ represents the duration of random access opportunities;

[0030] The calculation formula for the average number of random access opportunities R(X, Y) is expressed as:

[0031]

[0032] Wherein, i represents the number of current access devices, and k represents the number of antennas.

[0033] In the above-mentioned optimization method for device-free random access in a delay-sensitive scenario, the steps of dynamically adjusting the allocation proportion of preambles and the selection probability of emergency communication devices by using the particle swarm optimization algorithm are as follows:

[0034] Step 3.1: Initialize the acceleration constants C 1 and C 2 , the number of particles F, the velocity V, the variable X = {a, p, k}, the best position f of each particle * , the best position g of all particles * and the number of iterations I;

[0035] Step 3.2: Iterate for each particle i, i ≤ k: I, calculate the objective function value J(X i ) corresponding to the current position of each particle i, and compare the objective function value J(X i ) corresponding to the current position with the objective function value of the local optimal position and the objective function value of the global optimal position respectively, and update the best position f of each particle * and the best position g of all particles * according to the comparison results;

[0036] Step 3.3: Continuously iterate and optimize through the velocity and position update formulas to obtain the optimal solution of the best position g of all particles * ;

[0037] Step 3.4: According to the obtained best position g of all particles * = {a * , p * , k* The optimal solution of {}, extract the allocation ratio a of the optimal preamble * and the optimal emergency communication device selection probability p * .

[0038] In the above-mentioned optimization method for device-unauthorized random access in a latency-sensitive scenario, the calculation formulas for speed and position update are as follows:

[0039] V^ = V + C 1 *rand()*(f * - X) + C 2 *rand()*(g * - X);

[0040] V^ = X + V;

[0041] In the formula, rand() represents a random function, and V^ represents the speed after iteration.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The present invention introduces an emergency random access preamble, divides the emergency random access preamble and the ordinary preamble subsets, allows the emergency communication device to preferentially select the emergency random access preamble subset for access, reduces the collision probability, and ensures low-latency access. The present invention uses the particle swarm optimization algorithm to dynamically adjust the allocation ratio of the preamble and the emergency communication device selection probability, and continuously iterates and optimizes through the speed and position update formulas, ensuring the access performance. The present invention can formulate different access modes and resource scheduling strategies for different types of emergency events by setting emergency matter judgment and a secondary protocol, ensuring fast response processing, optimizing resource scheduling and allocation, and thus ensuring the processing priority and timeliness. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a flowchart of the method of the present invention;

[0045] Figure 2 is a schematic diagram of the preamble selection situation of the present invention;

[0046] Figure 3 is a schematic diagram of SP1 access of the present invention;

[0047] Figure 4 is a schematic diagram of SP2 access of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0048] The following further describes the present invention with reference to the drawings and embodiments, but it shall not be used as a basis for limiting the present invention.

[0049] Embodiment: An optimization method for device-unauthorized random access in a latency-sensitive scenario, as Figure 1 As shown, the specific steps include:

[0050] Step 1: Based on the Multiple-Input Multiple-Output (MIMO) technology, an emergency random access preamble (ERA) subset and a common preamble subset are divided, wherein the ERA subset is used for priority access of emergency communication equipment (EMs); in this embodiment, a part of the subsets are separated from the original common preamble (Random Access Preamble, RA) set, and these subsets are defined as emergency random access preambles. The preamble selection at this time is as follows Figure 2 shown.

[0051] Step 2: An emergency module is set at the transmitting end, and the emergency module authorizes the device to be an emergency communication device or a common device. The emergency communication device obtains the right to use the emergency random access preamble code, and the unauthorized common device uses the common preamble code;

[0052] In this embodiment, an emergency module is set at the transmitter, and the ERA authority is limited by the emergency module. When the operator or the automated program enables the emergency module, the emergency module authorizes the transmitter. The authorized device is an emergency communication device (emergency massive machine type communications, EMs), and the unauthorized device is a common device (common massive machine type communications, CMs). The transmitter obtains the authority and uses ERA, thereby effectively resolving the collision during the device access process and helping to achieve efficient resource acquisition.

[0053] Setting up the emergency module mainly includes the following steps:

[0054] Step 2.1: Set up emergency situation assessment and secondary protocol; the emergency situation assessment (ESA) includes continuous access option, periodic access option and single access option; continuous access option: in the face of special situations where contact needs to be maintained for a period of time, set the maximum duration of emergency access for a single time, allowing the device terminal to continuously occupy the channel during this time; periodic access option: in the face of emergency events that require communication and have periodic characteristics, agree on RA between the transmitter and the access point AP; single access option: the emergency is a one-time event and can be resolved by establishing a connection once.

[0055] The Secondary Protocol (SP) includes SP1 corresponding to the continuous access option, SP2 corresponding to the periodic access option, and SP3 corresponding to the single access option. The emergency matter judgment is the judgment of the type of emergency matter by the transmitting end, and the secondary protocol stipulates the subsequent procedures between the transmitting end and the access point AP. By setting the emergency matter judgment (ESA) and the secondary protocol (SP), the present invention can formulate different access modes and resource scheduling strategies for different types of emergency events, ensure fast response processing, optimize resource scheduling and allocation, so as to ensure the processing priority and timeliness.

[0056] SP1: The transmitting end's emergency matter judgment speculates the minimum continuous access time required to solve the event, loads the time into the secondary protocol, and transmits it to the access point AP. After receiving the secondary protocol, the access point AP changes the continuous time to t < t max (t max is the access delay requirement of EMs); when the connection time is close to t, the transmitting end sends a Continue Connection Request (CCR) based on the actual situation. When t = t max or the transmitting end actively disconnects the connection, the connection is disconnected, as Figure 3 shown.

[0057] SP2: The transmitting end stipulates the cycle number n and duration T. After the receiving device accepts, it establishes a device-channel-cycle protocol. The access point AP sends an RRC connection request with the device tag taken away (RRC-DT) with the transmitting end's tag every T interval. And if the information is small, the information can be directly sent together with the RRC connection request, repeating n times; the transmitting end receives the RRC-DT and establishes a connection; when the cycle ends or the transmitting end actively disconnects the connection, the connection is disconnected, as Figure 4 shown. RRC (Radio Resource Control), that is, radio resource control. It is a protocol layer between the UE (user equipment) and the eNodeB (base station), mainly responsible for the functions of the control plane, managing and scheduling radio resources to ensure stable and efficient communication.

[0058] SP3: After the SRRC is successfully established, the connection is made using the conventional process. SRRC represents the Secondary Radio Resource Control, that is, a protocol layer extended on the basis of the standard RRC (Radio Resource Control) protocol, used to handle specific service requirements.

[0059] Step 2.2: Set up the Emergency Access Lane (EAL). After the device terminal receives the Random Access Response (RAR), it determines whether to add a secondary protocol to the RRC connection request based on the emergency matter, and forms an SRRC connection request.

[0060] Step 2.3: Set up the Secondary Protocol Establishment Request (SPE). The access point AP accepts the SRRC connection request, and at the same time calls resources according to the secondary protocol. After the resource scheduling is completed, the SPE is added to the RRC establishment request to form an SRRC establishment request.

[0061] Step 3: Dynamically adjust the allocation ratio of preambles and the selection probability of emergency communication devices by using the particle swarm optimization algorithm to minimize the access delay of ordinary devices and meet the access delay constraints of emergency communication devices, and allocate corresponding access modes and resource scheduling strategies for different emergency event types.

[0062] For the coexistence system of massive machine type communication (mMTC) and ultra-reliable low-latency communication (uRLLC), the access delay is a key performance indicator because it plays an important role in the end-to-end delay. Therefore, in this embodiment, the average access delays of EMs and CMs are analyzed based on the introduction of the MIMO system to evaluate the performance.

[0063] To obtain the analysis of the delay optimization design mechanism, the performance of the traditional distributed queuing mechanism is first analyzed. When X devices communicate with a base station with k antennas using Y preambles, the calculation formula for the access delay of the devices is:

[0064] T(X, Y) = R(X, Y) * T^;

[0065] In the formula, X represents the number of access devices, Y represents the number of preambles used, R(X, Y) represents the average number of random access opportunities, and T^ represents the duration of the random access opportunity.

[0066] The calculation formula for the average number of random access opportunities R(X, Y) is expressed as:

[0067]

[0068] In the formula, i represents the number of currently accessing devices, C represents the number of ordinary devices, and k represents the number of antennas.

[0069] In this embodiment, the number of devices selecting emergency random access preambles is pE. For ordinary preambles, the number is C + (1 - p)E, and the access delay T of the ordinary devices C The calculation formula is:

[0070] T C = T(C + (1 - p)E, aN);

[0071] Wherein, p represents the proportion of selecting the emergency random access preamble, E represents the number of emergency communication devices, a represents the allocation proportion of the preamble, and N represents the number of preambles.

[0072] The access delay T of the emergency communication device E has the following calculation formula:

[0073]

[0074] Wherein, p represents the proportion of devices selecting the emergency random access preamble, E represents the number of emergency communication devices, a represents the allocation proportion of the preamble, and N represents the number of preambles.

[0075] After introducing MIMO, for the coexistence of hybrid traffic, the allocation proportion a of the preamble, the proportion p of devices selecting the emergency random access preamble, and the number of antennas k have a great impact on the access delays of EMs and CMs. A smaller splitting ratio a of the preamble can ensure the access delay of EMs. However, due to fewer preambles, it will simultaneously reduce the access performance of CMs. In addition, that EMs only select the preambles for EMs can reduce the collision probability, but a larger a may increase the access delay of EMs. In this case, the allocation proportion a of the preamble and the proportion p of devices selecting the emergency random access preamble should be jointly optimized according to the traffic load and the number of preambles. On the one hand, it can ensure the access performance of EMs with low access delay requirements; on the other hand, it can reduce the access delay of CMs to improve the system performance. Therefore, based on the time-delay optimization design, the optimization problem of minimizing the access delay of CMs can be expressed as:

[0076]

[0077] Satisfying

[0078] T E ≤ t max ;

[0079] 0 ≤ p ≤ 1;

[0080] 0 ≤ a ≤ 1;

[0081] Wherein, t max is the access delay requirement of the emergency communication device.

[0082] The problem involved in the optimization problem of minimizing the access delay of CMs belongs to the category of NP-hard problems. To efficiently obtain a suboptimal solution for this optimization problem, a heuristic algorithm, the Particle Swarm Optimization (PSO) algorithm, is selected. This algorithm has the advantages of low computational complexity and fast convergence speed, and can better handle such complex problems while ensuring efficiency.

[0083] Based on PSO, the access delay is regarded as the fitness function, and the number E of EMs, the number C of CMs, the number k of antennas, and the number N of preambles are initialized.

[0084] Specifically, the steps of using the particle swarm optimization algorithm to dynamically adjust the allocation ratio of preambles and the selection probability of emergency communication devices are as follows:

[0085] Step 3.1: Initialize the acceleration constants C 1 and C 2 , the number of particles F, the velocity V, the variable X = {a, p, k}, the best position f of each particle * , the best position g of all particles * and the number of iterations I;

[0086] Step 3.2: Iterate for each particle i, i ≤ k: I, calculate the objective function value J(X i ) corresponding to the current position of each particle i, and compare the objective function value J(X i ) corresponding to the current position with the objective function value of the local optimal position and the objective function value of the global optimal position respectively, and update the best position f of each particle * and the best position g of all particles * according to the comparison results;

[0087] Among them, if then update the local optimal position f of this particle * = X i ; if then update the global optimal position g * = X i .

[0088] Step 3.3: Continuously iterate and optimize through the velocity and position update formulas to obtain the optimal solution of the best position g of all particles * ;

[0089] Among them, the velocity and position update calculation formulas are as follows:

[0090] V^ = V + C 1 *rand()*(f * - X) + C 2 *rand()*(g* -X);

[0091] V^ = X + V;

[0092] where rand() represents the random function and V^ represents the velocity after iteration.

[0093] Step 3.4: According to all the best positions g of the particles obtained * = {a * , p * , k *}, extract the allocation ratio a of the optimal preamble * and the selection probability p of the optimal emergency communication device * .

[0094] All parameters converge after I iterations. When the iteration ends, the global optimal position g * = {a * , p * , k *} is a determined vector.

[0095] Extract the parameters related to the required optimal solution from g * , that is, find the allocation ratio a of the optimal preamble * and the selection probability p of the optimal emergency communication device * in the search space through the particle swarm optimization algorithm, so that the objective function value is optimal.

[0096] The present invention introduces an emergency random access preamble (ERA), divides the ERA subset and the normal preamble subset, allows emergency communication devices (EMs) to preferentially select the ERA subset for access, reduces the collision probability, and ensures low-latency access. The present invention dynamically adjusts the preamble allocation ratio and selection probability through particle swarm optimization (PSO) to meet the low-latency requirements of emergency communication devices. When the total number of devices E = 1000, p = 0.6 (proportion of EMs), N = 100 (total number of preambles), k = 4 (number of antennas), a = 0.7 (preamble allocation ratio), it can be calculated that in the present invention, the successful access probability of EMs is increased to 98.7%, and the preamble collision probability is reduced by 40% - 60%; the access delay fluctuation of CMs is reduced by 65%, and the optimization amplitude reaches 30% - 45%.

[0097] The present invention uses the PSO algorithm to dynamically adjust the preamble allocation ratio a and the selection probability p of the emergency communication device, takes the access delay as the fitness function, and continuously iteratively optimizes through the velocity and position update formulas. When the number of particles F = 50 and the maximum number of iterations I = 100, the optimal solution a * = 0.75, p *= 0.65. After optimization, the access delay of EMs is about 0.0433 milliseconds, with little change, meeting the delay requirements; the access delay of CMs remains 0.065 milliseconds, ensuring the access performance.

[0098] In summary, the present invention can improve the device access probability, reduce the access delay, optimize the resource scheduling, and enhance the emergency handling ability.

Claims

1. A method for optimizing random access of devices without authorization in delay-sensitive scenarios, characterized in that: The specific steps include: Step 1: In a multiple-input multiple-output system, an emergency random access preamble and a normal preamble are divided, wherein the emergency random access preamble is used for priority access of emergency communication equipment; Step 2: An emergency module is set at the transmitting end, and the emergency module authorizes the device to be an emergency communication device or a common device. The emergency communication device obtains the right to use the emergency random access preamble code, and the unauthorized common device uses the common preamble code; Step 3: Use the particle swarm optimization algorithm to dynamically adjust the preamble allocation ratio and the probability of emergency communication device selection to minimize the access delay of ordinary devices and meet the access delay constraint of emergency communication devices, and allocate corresponding access modes and resource scheduling strategies for different emergency event types.

2. The method for optimizing the authorization-free random access of devices in delay-sensitive scenarios according to claim 1, characterized in that: In step 2, setting up the emergency module mainly includes the following steps: Step 2.1: Set up emergency judgment and secondary protocol. Emergency judgment is the transmitter's judgment on the type of emergency event. The secondary protocol specifies the subsequent procedures between the transmitter and the access point AP. Step 2.2: Setting up the emergency channel. After receiving the random access response, the device terminal adds a secondary protocol to the SRRC connection request according to the emergency judgment to form an SRRC connection request; Step 2.3: Set up the secondary protocol establishment request. The access point AP accepts the SRRC connection request and calls resources according to the secondary protocol. After the resource scheduling is completed, SPE is added to the RRC establishment request to form an SRRC establishment request.

3. The method for optimizing the random access of devices without authorization in delay-sensitive scenarios according to claim 2, characterized in that: In step 2.1, the emergency decision ESA includes a continuous access option, a periodic access option and a single access option; the secondary protocol includes a secondary protocol SP1 corresponding to the continuous access option, SP2 corresponding to the periodic access option and SP3 corresponding to the single access option.

4. The method for optimizing the device authorization-free random access for delay-sensitive scenarios according to claim 3, characterized in that: The secondary protocol SP1 refers to the minimum continuous access time required for the transmitter to judge and infer the emergency event and solve the event, and loads the time into the secondary protocol and transmits it to the access point AP. After the access point AP receives the secondary protocol, t max is the access delay requirement of EMs, and the duration is changed to t<t max ; When the connection time approaches t, the transmitter sends a request to continue the connection based on the actual situation. When t=t max Or when the sender actively disconnects, the connection is disconnected.

5. The method for optimizing the random access of devices without authorization in delay-sensitive scenarios according to claim 3, characterized in that: The secondary protocol SP2 refers to the transmitter specifying the number of cycles n and duration T. After the receiving device accepts it, the device-channel-period protocol is established. The access point AP sends an RRC connection request with a transmitter tag every interval T, and if the information is small, the information can be directly sent together with the RRC connection request, and repeated n times; the transmitter receives the RRC connection request and establishes a connection; when the cycle ends or the transmitter actively disconnects, the connection is disconnected.

6. The method for optimizing the authorization-free random access of devices in delay-sensitive scenarios according to claim 3, characterized in that: The secondary protocol SP3 refers to the use of a conventional process to establish a connection after the SRRC is successfully established.

7. The method for optimizing the device authorization-free random access for delay-sensitive scenarios according to claim 1, characterized in that: The calculation formula of the access delay TC of the common device is: TC = T(C + (1-p)E, aN); In the formula, C represents the number of common devices, p represents the proportion of selecting emergency random access preambles, E represents the number of emergency communication devices, a represents the allocation ratio of preambles, N represents the number of preambles; T(X, Y) represents the access delay, and the calculation formula is: T(X, Y) = R(X, Y) * T^; Where X represents the number of access devices, Y represents the number of preambles used, R(X, Y) represents the average number of random access opportunities, and T^ represents the duration of a random access opportunity. The calculation formula of the average number of random access opportunities R(X, Y) is expressed as: In the formula, i represents the number of currently connected devices, and k represents the number of antennas.

8. The method for optimizing the random access of devices without authorization in delay-sensitive scenarios according to claim 1, characterized in that: The access delay T of the emergency communication device E The calculation formula is: In the formula, C represents the number of common devices, p represents the proportion of selecting emergency random access preambles, E represents the number of emergency communication devices, a represents the allocation ratio of preambles, N represents the number of preambles; T(X, Y) represents the access delay, and the calculation formula is: T(X, Y) = R(X, Y) * T^; Where X represents the number of access devices, Y represents the number of preambles used, R(X, Y) represents the average number of random access opportunities, and T^ represents the duration of a random access opportunity. The calculation formula of the average number of random access opportunities R(X, Y) is expressed as: In the formula, i represents the number of currently connected devices, and k represents the number of antennas.

9. The method for optimizing the random access of devices without authorization for delay-sensitive scenarios according to claim 7 or 8, characterized in that: The steps of dynamically adjusting the preamble allocation ratio and the probability of emergency communication equipment selection using the particle swarm optimization algorithm are as follows: Step 3.1: Initialize acceleration constants C1 and C2, number of particles F, velocity V, variable X = {a, p, k}, optimal position f of each particle * , the optimal position g of all particles * and the number of iterations I; Step 3.2: Iterate for each particle i, i≤k:I, and calculate the objective function value J(X i ), the objective function value J(X i ) are respectively related to the objective function value of the local optimal position And the objective function value of the global optimal position Compare and update the optimal position f of each particle according to the comparison results * and the optimal position g of all particles * ; Step 3.3: Continuously iterate and optimize the speed and position update formula to obtain the optimal position g of all particles * The optimal solution of Step 3.4: According to the best position g of all particles obtained * ={a * , p * , k * }, extract the optimal preamble allocation ratio a * and the optimal emergency communication equipment selection probability p * .

10. The method for optimizing the device authorization-free random access for delay-sensitive scenarios according to claim 9, characterized in that: The speed and position update calculation formula is as follows: V^=V+C1*rand()*(f * -X)+C2*rand()*(g * -X); V^=X+V; In the formula, rand() represents the random function, and V^ represents the speed after iteration.

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