A Conflict Resolution Method and System for a Communication System Based on Slotted ALOHA and NOMA

Abstract

The present invention discloses a method and system for conflict resolution in a communication system based on slotted ALOHA and NOMA. A communication system model combining slotted ALOHA and NOMA is constructed. The communication system model includes unauthorized random access of N users. The N user nodes are accessed to the network formed by the communication model according to Q1 newly allocated packet transmission power levels, and the collided data packets are moved into the collision queue. Conflict resolution is synchronously performed on the obtained collision queue based on the FCFS algorithm. The collision queue that has not been resolved after completion is saved, and the feedback information (0, 1, e) and R, L after the end of the Mth time slot are recorded. The time slot number, the lower threshold of the decomposition interval, and the collision queue are updated according to the feedback information (0, 1, e) and R, L. Conflict resolution is performed on the obtained collision queue based on the FCFS algorithm until all data packets are successfully transmitted. The present invention can obtain a higher passing rate and a lower average delay, and realizes the improvement of the system passing rate and delay performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communication, and particularly relates to a method and system for conflict resolution in a communication system based on slotted ALOHA and non-orthogonal multiple access (NOMA). Background Art

[0002] As a basic communication scenario in the 5G era, massive machine type communication (mMTC) has a large number of terminals. Each terminal needs to transmit a small amount of data and has weak delay sensitivity, requiring large-scale access with smaller data packets.

[0003] Grant-free random access is an access method proposed in the massive machine communication scenario to reduce data delay and save the overhead of control signaling. Users can directly transmit metadata and data to the base station without waiting for any permission.

[0004] Slotted ALOHA is a random access method proposed based on pure ALOHA. The system divides the time domain into several time slots with the same length as the data packet. Each packet can only be transmitted at the beginning of the time slot, and the system performance in terms of throughput is improved by reducing the vulnerable interval.

[0005] As an important technology in the 5G era, non-orthogonal multiple access technology can achieve effective reuse of spectrum resources, solve the problem of collision of some data packets, and obtain a lower packet loss rate and a higher throughput. Currently, more research is focused on power-domain non-orthogonal multiple access technology. The system selects different transmission powers at the sending end and performs successive interference cancellation at the receiving end to achieve multiple access through different power levels under the same time-frequency resource conditions.

[0006] In a communication system combining slotted ALOHA and NOMA, data packets randomly access in an unauthorized manner, and their arrival times and transmission powers are randomly distributed. The data packets arriving in a certain time slot are transmitted simultaneously at the beginning of the next time slot. If they are all at different power levels, the receiving end can decode them using NOMA technology.

[0007] The conflict resolution algorithm was proposed to solve the problem of how to ensure that all colliding data packets can be successfully transmitted in a competitive multiple access protocol. The two most common conflict resolution methods are the tree conflict resolution algorithm and the FCFS first-come, first-served splitting algorithm. Based on these two methods, some papers have proposed improved methods, such as the enhanced conflict resolution algorithm, the conflict resolution algorithm based on the business prediction model, and the probability-based ALOHA algorithm. The essence of this type of improved algorithm is still consistent with the FCFS first-come, first-served splitting algorithm. According to the conflict resolution situation, the length and starting time of the allocation interval are dynamically adjusted.

[0008] When the FCFS algorithm is applied to the system combining slotted ALOHA and NOMA, the transmission order of data packets is basically consistent with the arrival order, that is, it satisfies the first-come-first-decomposition principle. However, there are also some problems:

[0009] 1. As the arrival rate of new packets increases, the probability of collision of newly arrived data packets also gradually increases. A large number of data packets are accumulated in the waiting area. The system is always in the process of conflict resolution, and the throughput rate is affected.

[0010] 2. A large number of new packets that should have been transmitted in the corresponding time slots are piled up at the end of the queue, affecting the average delay. Summary of the invention

[0011] The technical problem to be solved by the present invention is to provide a communication system conflict decomposition method and system based on time slot ALOHA and NOMA in response to the deficiencies in the above-mentioned prior art, which is used to solve the technical problem that colliding data packets cannot be reasonably scheduled, so as to improve the system's pass rate and reduce the average delay.

[0012] The present invention adopts the following technical solutions:

[0013] A communication system conflict decomposition method based on slotted ALOHA and NOMA includes the following steps:

[0014] S1. Construct a communication system model combining slotted ALOHA and NOMA. The communication system model includes random access of N users without authorization.

[0015] S2, connecting the N user nodes in step S1 to the network formed by the communication model according to the allocated Q1 new packet transmission power levels, and moving the colliding data packets into the collision queue;

[0016] S3, synchronously performing conflict decomposition on the collision queue obtained in step S2 based on the FCFS algorithm;

[0017] S4, save the collision queue that has not been resolved after step S3, and record the feedback information (0, 1, e) and R, L after the end of the Mth time slot;

[0018] S5. Update the time slot number Pa according to the feedback information (0, 1, e) obtained in step S4 and R, L id , decompose the lower threshold t of the interval down and the collision queue;

[0019] S6. Based on the FCFS algorithm, decompose the collision queue obtained in step S5 until all data packets are successfully transmitted.

[0020] Specifically, step S1 is as follows:

[0021] S101. Construct a communication system where N users are independent of each other and have the same distance to the central base station;

[0022] S102. In terms of power, divide the system into Q levels, where Q1 power levels are used for the transmission of newly arrived data packets and Q2 power levels are used for collision resolution;

[0023] S103. From the path loss L p it is obtained that the path losses of all nodes are the same when the distances are the same;

[0024] S104. Substitute the transmission power level threshold P Ti into the received power P r to calculate the received power level thresholds P Rj ;

[0025] S105. After the data packet sent by the user arrives at a certain moment, randomly transmit at any power within the assigned power level at the start time of the next time slot;

[0026] S106. When multiple data packets are transmitted simultaneously in a time slot, the signal received at the receiving end contains multiple superimposed signals. For signals at different power levels, use non-orthogonal multiple access technology to first demodulate the signal with higher power. At this time, regard other signals as noise, then remove the demodulated signal from the received signal, continue to demodulate other signals, and successfully distinguish the data packets. The data packet transmission within the time slot is successful. On the contrary, if there is a situation where the data packets transmitted within this time slot occupy the same power level and cannot be distinguished, the data packet transmission within the time slot fails.

[0027] Specifically, step S2 is as follows:

[0028] S201. At the start time of the next time slot after the arrival time of the node, each distributed node transmits at any level among the Q1 power levels assigned in step S1 and demodulates the received signal;

[0029] S202. After a time slot ends, the feedback information obtained by the system is (1, e), where 1 indicates that there is no data packet transmission in this time slot, that is, this time slot is an idle time slot or all the transmitted data packets in this time slot are successfully transmitted, and e indicates that a collision occurs in the time slot and the data packet transmission fails.

[0030] S203. When the feedback information e is detected, the communication system sends all the data packets transmitted in the time slot into the collision queue in the order of arrival.

[0031] S204. Whether or not a collision occurs, the new packet transmission process continues as the time slot moves backward until the end of the new Nth packet transmission cycle, that is, the end of the Mth time slot transmission.

[0032] Specifically, step S3 is as follows:

[0033] S301. In an extreme case, the difference 2T0 between the moment of obtaining the collision feedback and the moment of data packet arrival, that is, the difference between the moment of obtaining the feedback and the arrival moment of all data packets in the corresponding time slot is less than 2T0, and the arrival moment of the collision queue is delayed by 2T0 based on the original arrival moment at the communication system, and then conflict resolution is performed.

[0034] S302. Set the initial allocation interval length to α0, initialize the moment t0 when the conflict resolution is completed to 0, initialize the lower threshold t of the allocation interval down = 0, the L set and the R set are used to store data packets, and record the current time slot number as Pa id ;

[0035] S303. Define the allocation interval length of the first time slot as α = min(α o , Pa id - t down ), and transmit the data packets with arrival moments within (t down , t down + α) at the start moment of the Pa id th time slot with any power level among the Q2 power levels allocated in step S1. After decoding using the NOMA technology, update the collision queue.

[0036] S304. At the end moment of the time slot, the time slot number Pa id moves backward by one bit. The feedback information obtained by the communication system is (0, 1, e), where 0 indicates that the time slot is empty and no data packet is transmitted, 1 represents that the data packet in the time slot is successfully transmitted, and e indicates that a collision occurs in the time slot. The communication system obtains the feedback that the data transmitted in this time slot is from the L set or the R set.

[0037] S305. Determine the changes of the corresponding parameters according to different feedbacks, and determine the data packets to be transmitted in the next time slot.

[0038] S306. Repeat steps S303 to S305 until the time slot sequence number Pa id = M.

[0039] Furthermore, in step S305, the determination of the corresponding parameter changes according to different feedbacks includes:

[0040] Feedback e indicates that a collision occurs in this time slot. The current assigned interval is evenly divided into L and R sets. The L set is transmitted in the next time slot, and the lower threshold t down remains unchanged, and the length α of the assigned interval is reduced to half of the original;

[0041] Feedback 1, L indicates that the L set is successfully transmitted in this time slot, and the corresponding R set needs to be transmitted in the next time slot. The lower threshold t down is updated to t down + α, and the length α of the assigned interval remains unchanged;

[0042] Feedback 0, L indicates that the L set is transmitted in this time slot and it is found that the L set is an empty set. In this case, there is no need to attempt to transmit the corresponding R set in the next time slot. Instead, the R set is decomposed into L and R sets again, and the new L set is transmitted in the next time slot. The lower threshold t down is updated to t down + α, and the length α of the assigned interval is reduced to half of the original;

[0043] Feedback R (0 or 1) indicates that the R set transmitted by R in this time slot is an empty set or is successfully transmitted. One conflict resolution cycle ends, and the next cycle is started. The lower threshold t down is updated to t down + α, and the assigned interval α is updated to α = min(α o , Pa id - t down ).

[0044] Specifically, step S3 is carried out synchronously with step S2, and the running time is the (1 - M)th time slot.

[0045] Specifically, step S5 is specifically as follows:

[0046] S501. Judge the last conflict resolution cycle corresponding to the end moment of step S3. When the feedback information is 0, R or 1, R, the last conflict resolution cycle has been completed; otherwise, the last conflict resolution cycle has not been completed;

[0047] S502. When the last conflict resolution cycle has not been completed, continue to decompose. When transmitting, randomly select the power among Q power levels until the conflict resolution cycle is completed, update the collision queue and record the time slot sequence number Pa id , and the lower threshold t of the allocation interval down is updated to t down + α;

[0048] When the last conflict resolution cycle is completed, the time slot sequence number Pa id is determined to be M.

[0049] Specifically, step S6 is specifically as follows:

[0050] S601. Set the initial allocation interval length to α1, and move the time slot sequence number Pa id one position backward;

[0051] S602. Transmit the data packets whose arrival times are within (t down , t down +α) at any power level among the Q power levels allocated in S1 at the start time of the Pa id -th time slot, and decode using the NOMA technology;

[0052] S603. At the end time of the time slot, move the time slot sequence number Pa id one position backward. The feedback information that the system needs to obtain is (0, 1, e). 0 indicates that the time slot is empty and no data packet is transmitted. 1 represents that the data packet in this time slot is successfully transmitted. e indicates that a collision occurs in the time slot, and the communication system obtains the feedback that the data transmitted in this time slot is from the L set or the R set;

[0053] S604. Determine the changes of the corresponding parameters according to different feedbacks, and determine the data packets to be transmitted in the next time slot;

[0054] S605. Repeat steps S602 to S604 until the collision queue is an empty set and all data packets are successfully transmitted.

[0055] Furthermore, in step S604, determining the changes of the corresponding parameters according to different feedbacks includes:

[0056] Feedback e represents that a collision occurs in this time slot. Divide the current allocation interval evenly into the L and R sets, transmit the L set in the next time slot, keep the lower threshold t down unchanged, and reduce the allocation interval length α to half of the original;

[0057] Feedback 1, L represents that the L set is successfully transmitted in this time slot. The corresponding R set needs to be transmitted in the next time slot. Update the lower threshold t down to t down +α, and keep the allocation interval length α unchanged;

[0058] Feedback 0, L represents that the L set is transmitted in this time slot and it is found that the L set is an empty set. At this time, in the next time slot, do not decompose the R set into the L and R sets again, transmit a new L set in the next time slot, update the lower threshold t down to t down +α, and reduce the allocation interval length α to half of the original;

[0059] The length of the assigned interval α is directly updated to α1.

[0060] In a second aspect, an embodiment of the present invention provides a communication system conflict resolution system based on slotted ALOHA and NOMA, including:

[0061] Building module, building a communication system model combining slotted ALOHA and NOMA, the communication system model includes N users with random access without authorization;

[0062] The allocation module connects the N user nodes in the construction module to the network formed by the communication model according to the allocated Q1 new packet transmission power levels, and moves the colliding data packets into the collision queue;

[0063] The synchronization module performs conflict resolution on the collision queue obtained by the allocation module based on the FCFS algorithm;

[0064] The recording module saves the collision queue that has not been decomposed after the synchronization module ends, and records the feedback information (0, 1, e) and R, L after the end of the Mth time slot;

[0065] Update module, based on the feedback information (0, 1, e) obtained by the recording module and R, L update the time slot number Pa id , decomposition interval lower threshold t down and collision queues;

[0066] The decomposition module performs conflict decomposition on the collision queue obtained by the update module based on the FCFS algorithm until all data packets are successfully transmitted.

[0067] Compared with the prior art, the present invention has at least the following beneficial effects:

[0068] A communication system conflict resolution method based on slotted ALOHA and NOMA is proposed. All data packets are accessed in an unauthorized random manner. Before the new packet transmission process ends, a (1, e) feedback method is added to exchange feedback information for system performance improvement. In the power domain, the conflict resolution process based on the FCFS algorithm and the transmission process of the new data packet are divided into two independent modules, each of which moves forward; after the new packet transmission process ends, the two processes are merged into a conflict resolution process, and all power in the power domain is used for conflict resolution, which effectively improves the system throughput performance and reduces the average delay.

[0069] Furthermore, the transmission mechanism of the communication system based on slotted ALOHA and NOMA is analyzed, and the system is divided into two parts: new packet transmission and conflict resolution in the power domain. The system model is defined to facilitate the subsequent presentation.

[0070] Furthermore, on the power domain allocated for the transmission of new packets, the data packets are transmitted according to the protocol rules until the new packet transmission process is completed. During this period, the collided data packets are sent into the collision queue, avoiding the situation that the new packets are piled up in the waiting area due to a long conflict resolution cycle, and ensuring a certain passing rate and average delay.

[0071] Furthermore, during the new packet transmission process, the power domain allocated for conflict resolution resolves the conflicts in the collision queue using the FCFS algorithm. The characteristics of the FCFS algorithm determine that the data packets in the collision queue are resolved in the order of arrival, effectively ensuring the average delay.

[0072] Furthermore, the system determines the transmission content of the next time slot according to the data packet transmission status of the previous time slot. This distributed transmission method effectively reduces the energy consumption of the system for scheduling data.

[0073] Furthermore, the transmission process of newly arrived data packets is synchronized with the conflict resolution process, achieving the function of fully utilizing power resources and ensuring the transmission order.

[0074] Furthermore, save the unresolved collision queue and the feedback information at the last moment, accurately record the system state, so as to facilitate the precise operation of subsequent programs.

[0075] Furthermore, determine the state of the system at the last moment of new packet transmission according to the feedback information, so as to directly enter the final link or first complete the current conflict resolution cycle, making the most of each time slot and power level.

[0076] Furthermore, use the FCFS algorithm to resolve the conflicts of the remaining data packets in the collision queue at all power levels until all packets are successfully transmitted, giving full play to the advantages of the NOMA technology, using all power levels, and effectively ensuring the system passing rate and experimental performance.

[0077] Furthermore, determine the data packets that need to be retransmitted in the next time slot according to the result of conflict resolution in the current time slot, ensuring that no data packets are missed.

[0078] It can be understood that the beneficial effects of the second aspect above can be referred to the relevant descriptions in the first aspect above, and will not be elaborated here.

[0079] In summary, the present invention can obtain a higher passing rate and a lower average delay, achieving the improvement of the system passing rate and delay performance.

[0080] Next, through the drawings and embodiments, the technical solutions of the present invention will be further described in detail. Description of the Drawings

[0081] Figure 1 It is a flowchart of the present invention;

[0082] Figure 2 Communication system model diagram constructed for the present invention;

[0083] Figure 3 Comparison chart of passing rates between the present invention and the FCFS algorithm when the total power level number Q = 3;

[0084] Figure 4 Comparison chart of average delays between the present invention and the FCFS algorithm when the total power level number Q = 3;

[0085] Figure 5 Comparison chart of passing rates between the present invention and the FCFS algorithm when the total power level number Q = 4;

[0086] Figure 6 Comparison chart of average delays between the present invention and the FCFS algorithm when the total power level number Q = 4. Detailed implementation manners

[0087] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the protection scope of the present invention.

[0088] In the description of the present invention, it should be understood that the terms "include" and "comprise" indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0089] It should also be understood that the terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms.

[0090] It should be further understood that the term " / and" used in the specification of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations. For example, A and / or B can represent: the existence of A alone, the existence of both A and B, and the existence of B alone. In addition, the character " / " in this article generally represents an "or" relationship between the preceding and following associated objects.

[0091] It should be understood that, although the terms first, second, third, etc. may be used to describe preset ranges, etc. in the embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are only used to distinguish preset ranges from each other. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0092] The word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0093] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0094] The present invention provides a communication system conflict resolution method based on time slot ALOHA and NOMA, which adopts an unauthorized random access method to access all data packets. Before the end of the new packet transmission process, a (1, e) feedback method is added to exchange feedback information for the improvement of system performance; in the power domain, the conflict resolution process based on the FCFS algorithm and the transmission process of the new data packet are divided into two independent modules, each of which moves forward; after the new packet transmission process is completed, the two processes are merged into a conflict resolution process, and all power in the power domain is used for conflict resolution, which effectively improves the throughput performance of the communication system and reduces the average delay.

[0095] See also Figure 1 The present invention provides a communication system conflict decomposition method based on time slot ALOHA and NOMA, comprising the following steps:

[0096] S1. Construct a model of the communication system of slotted ALOHA and NOMA with unlicensed random access of N users.

[0097] See also Figure 2 , the model of the communication system is as follows:

[0098] S101. Construct a communication system where the distances from N mutually independent users to the central base station are the same;

[0099] S102. In terms of power, divide the system into Q levels, where Q1 power levels are used for the transmission of newly arrived data packets and Q2 power levels are used for conflict resolution;

[0100] In the communication system, the length of each time slot, i.e., the transmission length of each data packet, is T0. Each time slot includes a broadcast segment and a data segment, and the broadcast segment broadcasts feedback information. There are a total of Q power levels, specifically as follows:

[0101] Q = Q1 + Q2

[0102] Among them, Q1 power levels are allocated for the transmission of new packets, Q2 power levels are allocated for conflict resolution, and the time length of one cycle is MT0, where M is a positive integer.

[0103] S103. From the path loss L p It is obtained that the path losses of all nodes are the same when the distances are the same;

[0104] The path loss L p Specifically:

[0105] L p = [c / (4πdf c )] 2

[0106] Among them, c is the speed of light, d is the transmission distance, and f c is the central frequency.

[0107] S104. Substitute the transmission power level threshold P Ti into the received power P r to calculate the received power level thresholds P Rj ;

[0108] The received power P r Specifically:

[0109] P r = P s G tx L p G rx

[0110] Among them, i = 1,..., L, j = 1,..., L, P s is the transmission power, G tx is the transmission antenna gain, and G rx is the receiving antenna gain.

[0111] S105. After the data packet sent by the user arrives at a certain moment, randomly transmit at any power within the assigned power level at the start time of the next time slot;

[0112] S106. When multiple data packets are transmitted simultaneously in a time slot, the signal received at the receiving end contains multiple superimposed signals. For signals at different power levels, use non-orthogonal multiple access technology to demodulate the signal with higher power first. At this time, regard other signals as noise, then remove the demodulated signal from the received signal, continue to demodulate other signals, and successfully distinguish the data packets, indicating that the data packet transmission within the time slot is successful. On the contrary, if there is a situation where the data packets transmitted within this time slot occupy the same power level and cannot be distinguished, the data packet transmission within the time slot fails.

[0113] S2. Connect the N user nodes in step S1 to the network formed by the communication model according to the Q1 new packet transmission power levels assigned. If a collision occurs, move the collided data packets into the collision queue, and the data packets in this queue will be sent to step S3 for collision resolution;

[0114] S201. At the start time of the next time slot after the node arrival time, each distributed node transmits at any level among the Q1 power levels assigned in step S1, and demodulate the received signal using the method in step S105;

[0115] S202. After a time slot ends, the feedback information that the system needs to obtain is (1, e). 1 indicates that there is no data packet transmission within this time slot, that is, this time slot is an idle time slot or all the data packets transmitted within this time slot are successfully transmitted, and e indicates that a collision occurs within this time slot and the data packet transmission fails;

[0116] S203. After monitoring the feedback information e, the system sends all the data packets transmitted within this time slot into the collision queue in the order of arrival, and performs collision resolution on the data packets in this queue in step S3;

[0117] S204. Whether a collision occurs or not, each step in step S2 continues with the shift of the time slot until the end of the new packet transmission cycle, that is, the end of the Mth time slot transmission.

[0118] S3. Based on the FCFS algorithm, perform collision resolution on the collision queue in step S2. Step S3 is synchronized with step S2, and the running time is the (1 - M)th time slot;

[0119] S301. In the most extreme case, the difference between the moment when the collision feedback is obtained and the data packet arrival moment is 2T0, that is, the difference between the moment when all data packets obtain feedback in the corresponding time slot and the arrival moment is less than 2T0. Therefore, the arrival moment of the collision queue is delayed by 2T0 based on the original arrival system moment, and then collision resolution is performed;

[0120] S302. Set the initial allocation interval length to α0, initialize the time t0 = 0 when conflict resolution is completed, initialize the lower threshold t of the allocation interval to 0, define the L set and the R set to store data packets, and record the slot sequence number currently in progress as Pa down ; id

[0121] S303. Define the allocation interval length α of the first slot as α = min(α o , Pa id - t down ), obtain the allocation interval of subsequent slots from step S305, and transmit the data packets with arrival times within (t down , t down + α) at the start time of the Pa id -th slot at any of the Q2 power levels allocated in step S1, decode them using NOMA technology, and update the collision queue after successful decoding;

[0122] S304. At the end of the slot, shift the slot sequence number Pa id one position backward. The feedback information that the system needs to obtain is (0, 1, e). 0 indicates that the slot is empty and no data packet is transmitted, 1 represents that the data packet in the slot is successfully transmitted, e indicates that a collision occurs in the slot. In addition, the system also needs to obtain the feedback on whether it is the L set or the R set transmitted in this slot;

[0123] S305. Determine the changes in the corresponding parameters according to different feedbacks and determine the data packets to be transmitted in the next slot;

[0124] Case 1:

[0125] The feedback e represents that a collision occurs in this slot. It is necessary to divide the current assigned interval into the L set and the R set on average, transmit the L set in the next slot, keep the lower threshold t down unchanged, and reduce the assigned interval length α to half of the original.

[0126] Case 2:

[0127] The feedback 1, L represents that the L set is successfully transmitted in this slot. The corresponding R set needs to be transmitted in the next slot. Update the lower threshold t down to t down + α, and keep the assigned interval length α unchanged.

[0128] Case 3:

[0129] The feedback 0, L represents that the L set is transmitted in this slot and it is found that the L set is an empty set. In this case, there is no need to attempt to transmit the corresponding R set in the next slot. Instead, decompose the R set into the L set and the R set again, transmit the new L set in the next slot, and update the lower threshold t down to t down ​+α, reduce the length of the assigned interval α to half of the original.

[0130] Case 4:

[0131] The feedback R (0 or 1) indicates that the R set transmitted in this time slot R is an empty set or a successful transmission. The end of a conflict resolution cycle, start the next cycle, and the lower threshold t down is updated to t down +α, the assigned interval α is updated to α = min(α o , Pa id -t down ).

[0132] S306. Repeat steps S303, S304, and S305 until Pa id = M.

[0133] S4. Save the collision queue that has not been resolved after the end of step S3, record the feedback information (0, 1, e) and R, L after the end of the Mth time slot, and enter step S5;

[0134] S5. Update the time slot sequence number Pa id , the lower threshold t of the decomposition interval down and the collision queue according to the feedback information obtained in step S4;

[0135] S501. Determine whether the last conflict resolution cycle corresponding to the end moment of step S3 is completed. If the feedback information is 0, R or 1, R, the last conflict resolution cycle has been completed; otherwise, the last conflict resolution cycle has not been completed;

[0136] S502. Perform the next operation according to the judgment result of step S501.

[0137] Case 1:

[0138] The last conflict resolution cycle has not been completed, then continue to decompose according to the process of step S305, but when transmitting, it is no longer limited to the levels in Q2 power levels, but randomly select the power in Q power levels until the conflict resolution cycle is completed, update the collision queue and record the time slot sequence number Pa at this time id , the lower threshold t of the allocation interval down is updated to t down +α.

[0139] Case 2:

[0140] The last conflict resolution cycle has been completed, and the time slot sequence number Pa id is determined to be M.

[0141] S6. Based on the FCFS algorithm, perform conflict resolution on the collision queue in step S5 until all data packets are successfully transmitted.

[0142] S601. Set the initial allocation interval length to α1 and the number of time slot sequence numbers to Pa id Shift it one place backward;

[0143] S602. Transmit the data packets whose arrival times are within (t down , t down +α) at the start time of the Pa id -th time slot with any power level among the Q power levels allocated in S1, decode it using NOMA technology, and update it after successful decoding;

[0144] S603. At the end time of the time slot, shift the time slot sequence number Pa id one place backward. The feedback information that the system must obtain includes (0, 1, e). 0 indicates that the time slot is empty and no data packet is transmitted. 1 represents that the data packet in the time slot is successfully transmitted. e indicates that a collision occurs in the time slot. In addition, the system also needs to obtain the feedback on whether it is the L set or the R set transmitted in this time slot;

[0145] S604. Determine the change of the corresponding parameters according to different feedbacks and determine the data packets to be transmitted in the next time slot;

[0146] Case 1:

[0147] The feedback e represents that a collision occurs in this time slot. It is necessary to evenly divide the current assigned interval into the L and R sets, transmit the L set in the next time slot, keep the lower threshold t down unchanged, and reduce the assigned interval length α to half of the original;

[0148] Case 2:

[0149] The feedback 1, L represents that the L set is successfully transmitted in this time slot. The corresponding R set needs to be transmitted in the next time slot. The lower threshold t down is updated to t down +α, and the assigned interval length α remains unchanged;

[0150] Case 3:

[0151] The feedback 0, L represents that the L set is transmitted in this time slot and it is found that the L set is an empty set. At this time, there is no need to attempt to transmit the corresponding R set in the next time slot. Instead, decompose the R set into the L and R sets again and transmit the new L set in the next time slot. The lower threshold t down is updated to t down +α, and the assigned interval length α is reduced to half of the original;

[0152] Case 4:

[0153] The assigned interval length α is directly updated to α1.

[0154] S605. Repeat steps S602, S603, and S604 until the collision queue is an empty set and all data packets are successfully transmitted.

[0155] In another embodiment of the present invention, a communication system conflict resolution system based on slotted ALOHA and NOMA is provided. This system can be used to implement the above-mentioned communication system conflict resolution method based on slotted ALOHA and NOMA. Specifically, the communication system conflict resolution system based on slotted ALOHA and NOMA includes a construction module, an allocation module, a synchronization module, a recording module, an update module, and a decomposition module.

[0156] Among them, the construction module constructs a communication system model combining slotted ALOHA and NOMA. The communication system model includes unauthorized random access of N users.

[0157] The allocation module accesses the network formed by the communication model with N user nodes in the construction module according to the Q1 new packet transmission power levels assigned, and moves the collided data packets into the collision queue.

[0158] The synchronization module resolves conflicts in the collision queue obtained by the allocation module based on the FCFS algorithm.

[0159] The recording module saves the collision queue that has not been resolved after the synchronization module ends, and records the feedback information (0, 1, e) and R, L after the end of the Mth time slot.

[0160] The update module updates the time slot number Pa id and the lower threshold t of the decomposition interval down and the collision queue according to the feedback information (0, 1, e) and R, L obtained by the recording module.

[0161] The decomposition module resolves conflicts in the collision queue obtained by the update module based on the FCFS algorithm until all data packets are successfully transmitted.

[0162] In another embodiment of the present invention, a terminal device is provided. The terminal device includes a processor and a memory. The memory is used to store a computer program, and the computer program includes program instructions. The processor is used to execute the program instructions stored in the computer storage medium. The processor may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, and is suitable for implementing one or more instructions. Specifically, it is suitable for loading and executing one or more instructions to implement the corresponding method flow or corresponding function. The processor described in the embodiment of the present invention can be used for the operation of the communication system conflict resolution method based on slotted ALOHA and NOMA, including:

[0163] Construct a communication system model combining slotted ALOHA and NOMA. The communication system model includes unauthorized random access of N users; access the network formed by the communication model with N user nodes according to the allocated Q1 new packet transmission power levels, and move the collided data packets into the collision queue; perform conflict resolution on the obtained collision queue synchronously based on the FCFS algorithm; save the collision queue that has not been resolved after the end, and record the feedback information (0, 1, e) and R, L after the end of the Mth time slot; update the time slot number Pa id , the lower threshold t of the decomposition interval down and the collision queue; perform conflict resolution on the obtained collision queue based on the FCFS algorithm until all data packets are successfully transmitted.

[0164] In another embodiment of the present invention, the present invention further provides a storage medium, specifically a computer-readable storage medium (Memory). The computer-readable storage medium is a memory device in a terminal device and is used to store programs and data. It can be understood that the computer-readable storage medium here can include both the built-in storage medium in the terminal device and, of course, the extended storage medium supported by the terminal device. The computer-readable storage medium provides a storage space, and the operating system of the terminal is stored in this storage space. And, one or more instructions suitable for being loaded and executed by a processor are also stored in this storage space. These instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory (Non-Volatile Memory), such as at least one disk memory.

[0165] One or more instructions stored in the computer-readable storage medium can be loaded and executed by a processor to implement the corresponding steps of the communication system conflict resolution method based on slotted ALOHA and NOMA in the above embodiments; one or more instructions in the computer-readable storage medium are loaded and executed by a processor to perform the following steps:

[0166] Construct a communication system model combining slotted ALOHA and NOMA. The communication system model includes unauthorized random access of N users; connect N user nodes to the network formed by the communication model according to the allocated Q1 new packet transmission power levels, and move the collided data packets into the collision queue; perform conflict resolution on the obtained collision queue synchronously based on the FCFS algorithm; save the collision queue that has not been resolved after completion, and record the feedback information (0, 1, e) and R, L after the end of the Mth time slot; update the time slot sequence number Pa id , the lower threshold t of the decomposition interval down and the collision queue; perform conflict resolution on the obtained collision queue based on the FCFS algorithm until all data packets are successfully transmitted.

[0167] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components described and shown in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0168] Simulation parameter settings:

[0169] Total number of time slots M for new packet arrivals: 1000

[0170] Initial allocation interval length α0 in stage S1 (unit: one time slot length): 2.6

[0171] Initial allocation interval length α1 in stage S2 (unit: one time slot length): 2.6

[0172] Packet arrival rate lamda: 0.5 - 3

[0173] Number of packets N: M * lamda

[0174] Number of repeated experiments: 100.

[0175] Please refer to Figure 3 , for the case where the number of power levels Q = 4, we respectively simulated the performance of the pure FCFS algorithm and the improved algorithm. Figure 3 It shows that when the system parameters are set to Q1 = 1, Q2 = 2 and Q1 = 2, Q2 = 1, the change relationship trend of the system passing rate of the improved algorithm with the new packet arrival rate is similar to that of the FCFS algorithm, both increasing first and then decreasing, and the improved algorithm is better than the FCFS algorithm. Among them, when the new packet arrival rate is 1, the maximum increase in the passing rate of the improved algorithm compared to the FCFS algorithm under the allocation method with power levels Q1 = 1, Q2 = 2 can reach about 10%.

[0176] Please refer to Figure 4 , for the case where the number of power levels Q = 4, we respectively simulated the performance of the pure FCFS algorithm and the improved algorithm. Figure 4 It shows that when the system parameters are set to Q1 = 1, Q2 = 2 and Q1 = 2, Q2 = 1, the average transmission delay of both allocation methods is better than that of the original FCFS algorithm. Among them, the maximum improvement in the delay performance under the allocation method with Q1 = 2, Q2 = 1 can reach about 20%.

[0177] Please refer to Figure 5 , for the case where the number of power levels Q = 5, we respectively simulated the performance of the pure FCFS algorithm and the improved algorithm. Figure 5 It shows that when the system parameters are set as Q1 = 1, Q2 = 3; Q1 = 2, Q2 = 2, and Q1 = 1, Q2 = 3, the changing relationship trend between the system passing rate and the new packet arrival rate of the improved algorithm is similar to that of the FCFS algorithm, both increasing first and then decreasing, and it is better than the FCFS algorithm. Among them, when the new packet arrival rate is 1.2, the maximum increase in the passing rate of the improved algorithm compared to the FCFS algorithm under the allocation methods of power levels Q1 = 1, Q2 = 3 and Q1 = 2, Q2 = 2 can reach about 25%.

[0178] Please refer to Figure 6 , for the case where the number of power levels Q = 5, we respectively simulated the performance of the pure FCFS algorithm and the improved algorithm. Figure 6 It shows that when the system parameters are set as Q1 = 1, Q2 = 3; Q1 = 2, Q2 = 2, and Q1 = 1, Q2 = 3, the average transmission delays of the three allocation methods are all better than the original FCFS algorithm. Among them, the allocation method of Q1 = 3, Q2 = 1 can improve the delay performance by up to about 30% at most.

[0179] In summary, a communication system conflict resolution method and system based on slotted ALOHA and NOMA of the present invention can obtain a higher passing rate and a lower average delay; by using the method of adding feedback information, the transmission process of new data packets and the conflict resolution process are separated in the power domain. During the transmission process of new packets, conflict resolution is carried out simultaneously. After the transmission process of new packets ends, the power levels are no longer divided, but all serve the conflict resolution process, effectively improving the passing rate and delay performance.

[0180] Those skilled in the art can clearly understand that, for the convenience and conciseness of description, only the above-mentioned division of each functional unit and module is used as an example. In actual applications, the above functions can be allocated to different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiments can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of each functional unit and module are only for the convenience of mutual distinction and do not limit the protection scope of the present application. The specific working processes of the units and modules in the above system can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated here.

[0181] In the above embodiments, the descriptions of the respective embodiments have their own emphases. For parts not described or recorded in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

[0182] Those of ordinary skill in the art can realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or by a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0183] In the embodiments provided by the present invention, it should be understood that the disclosed device / terminal and method can be implemented in other ways. For example, the device / terminal embodiments described above are merely illustrative. For example, the division of the modules or units is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, and the indirect couplings or communication connections of the devices or units can be in electrical, mechanical or other forms.

[0184] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or may be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0185] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0186] When the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, to implement all or part of the processes in the above-described embodiment methods of the present invention, it can also be completed by instructing relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps of the above-described various method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file, or some intermediate form, etc. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disc, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the content included in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0187] This application is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing device to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing device generate a device for implementing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0188] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device implements the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0189] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus, so that a series of operation steps are executed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions for implementing the steps of the process Figure 1 one process or a plurality of processes and / or blocks Figure 1 steps for implementing the functions specified in one block or a plurality of blocks.

[0190] The above is only to illustrate the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A conflict resolution method for a communication system based on slotted ALOHA and NOMA, characterized in that It includes the following steps: S1. Construct a communication system model that combines slotted ALOHA and NOMA. The communication system model includes the unlicensed random access of N users; S2. Connect the N user nodes in step S1 to the network formed by the communication system model according to the allocated new packet transmission power levels, and move the collided data packets into the collision queue; S3. Based on the FCFS algorithm, synchronously perform conflict resolution on the collision queue obtained in step S2. Step S3 is specifically as follows: S301. The difference between the moment of obtaining collision feedback and the packet arrival moment in extreme cases , that is, the difference between the moment of obtaining feedback for all packets in the corresponding time slot and the arrival moment is less than . The arrival moment of the collision queue is delayed by based on the moment in the original arrival communication system model, and then conflict resolution is performed; S302. Set the initial allocation interval length to , initialize the time when conflict resolution is completed , initialize the lower threshold of the allocation interval , the L set and the R set are used to store data packets, and record the current slot number as ; S303. The allocation interval length of the first time slot is defined as , and the data packets arriving at the moment within are transmitted at any power level among the power levels allocated in step S1 at the start time of the th time slot. After decoding using the NOMA technology, update the collision queue; S304. At the end of the time slot, the time slot number is shifted by one position. The feedback information obtained by the communication system model is (0, 1, e), where 0 indicates that the time slot is empty and no data packet is transmitted, 1 represents that the data packet in the time slot is successfully transmitted, and e indicates that a collision occurs in the time slot. The communication system model obtains the feedback that the data transmitted in this time slot is from set L or set R; S305. Determine the change of corresponding parameters according to different feedbacks, and determine the data packets to be transmitted in the next time slot; S306. Repeat steps S303 to S305 until the time slot number ; S4. Save the collision queue that has not been resolved after step S3 ends, and record the feedback information (0, 1, e) and the R set and L set after the end of the Mth time slot; S5. Update the time slot number according to the feedback information (0, 1, e) obtained in step S4, the R set, and the L set. Lower threshold of the decomposition interval and the collision queue. S6. Based on the FCFS algorithm, perform conflict resolution on the collision queue obtained in step S5 until all data packets are successfully transmitted.

2. The method for conflict resolution of a communication system based on slotted ALOHA and NOMA according to claim 1, wherein Step S1 is specifically as follows: S101. Construct a communication system model in which N users are independent of each other and have the same distance to the central base station; S102 divides the system into Q levels in terms of power, where levels of power are used for the transmission of newly arrived data packets, levels of power are used for conflict resolution; S103. From the path loss it is obtained that the path losses of all nodes are the same when the distances are the same; S104. Bring the transmission power level threshold into the received power to calculate the received power level thresholds for each level ; S105. After the data packets sent by the users arrive at a certain moment, randomly start the next time slot and transmit at any power within the assigned power level; S106. When multiple data packets are transmitted simultaneously in a time slot, the signal received at the receiving end contains multiple superimposed signals. For signals at different power levels, use non-orthogonal multiple access technology to first demodulate the signal with higher power. At this time, regard other signals as noise, then remove the demodulated signal from the received signal, continue to demodulate other signals, and successfully distinguish the data packets. The data packet transmission within the time slot is successful. On the contrary, if there is a situation where the data packets transmitted within this time slot occupy the same power level and cannot be distinguished, the data packet transmission within the time slot fails.

3. The method for conflict resolution of a communication system based on slotted ALOHA and NOMA according to claim 1, wherein Step S2 is specifically as follows: S201. At the start time of the next time slot after the node arrival time, each distributed node transmits at any of the power levels allocated in step S1, and demodulates the received signal. S202. After a time slot ends, the feedback information obtained by the system is (1, e). 1 indicates that there is no data packet transmission within this time slot, that is, this time slot is an idle time slot, or all the data packets transmitted within this time slot are successfully transmitted. e indicates that a collision occurs within the time slot and the data packet transmission fails; S203. When the feedback information e is detected, the communication system model sends all the data packets transmitted within the time slot into the collision queue in the order of arrival; S204. Whether a collision occurs or not, the new packet transmission process continues as the time slot moves backward until the end of the new Nth packet transmission cycle, that is, the end of the Mth time slot transmission.

4. The method for conflict resolution of a communication system based on slotted ALOHA and NOMA according to claim 1, wherein In step S305, determining the change of corresponding parameters according to different feedbacks includes: The feedback e indicates that a collision occurs in this time slot. The current allocation interval is evenly divided into L and R sets. The L set is transmitted in the next time slot, and the lower threshold remains unchanged, and the length of the allocation interval is reduced to half of the original; Feedback 1. L represents the set L of successful transmissions in this time slot. The corresponding set R needs to be transmitted in the next time slot, and the lower threshold is updated to , which refers to the length of the allocation interval and remains unchanged; Feedback 0, L indicates that L sets have been transmitted in this time slot and it is found that the L sets are empty sets. In this case, there is no need to attempt to transmit the corresponding R sets in the next time slot. Instead, the R sets are decomposed into L and R sets again, and the new L sets are transmitted in the next time slot. The lower threshold is updated to , and the length of the allocation interval is reduced to half of the original; The feedback R (0 or 1) indicates that the R set transmitted in this time slot R is an empty set or a successful transmission. The conflict resolution period ends, and the next period is started, with the lower threshold is updated to , the allocation interval is updated to .

5. The method for conflict resolution of a communication system based on slotted ALOHA and NOMA according to claim 1, characterized in that Step S3 is carried out synchronously with Step S2, and their running times are both the nth time slot.

6. The method for conflict resolution of a communication system based on slotted ALOHA and NOMA according to claim 1, wherein Step S5 is specifically as follows: S501. Judge the last conflict resolution cycle corresponding to the end moment of step S3. When the feedback information is 0, R or 1, R, the last conflict resolution cycle has been completed; otherwise, the last conflict resolution cycle has not been completed; S502. When the last conflict resolution period is not completed, continue the decomposition. Randomly select the power among Q power levels during transmission until the conflict resolution period is completed. Update the collision queue and record the slot sequence number at this time. , the lower threshold of the allocation interval is updated to ; When the last collision resolution cycle has been completed, the slot sequence number is determined to be M.

7. The method for conflict resolution of a communication system based on slotted ALOHA and NOMA according to claim 1, wherein Step S6 is specifically as follows: S601. Set the initial allocated interval length to , and shift the time slot sequence number one position backward; S602. Transmit the data packets with arrival times within at the start time of the th time slot at any of the Q power levels allocated in S1, and decode using NOMA technology; S603. At the end of a time slot, the time slot sequence number is shifted one position backward. The feedback information that the system needs to obtain includes (0, 1, e). 0 indicates that the time slot is empty and no data packet is transmitted. 1 represents that the data packet in this time slot is successfully transmitted. e indicates that a collision occurs in the time slot. The communication system obtains the feedback that the data transmitted in this time slot belongs to set L or set R; S604. Determine the change of corresponding parameters according to different feedbacks, and determine the data packets to be transmitted in the next time slot; S605. Repeat steps S602 to S604 until the collision queue is an empty set and all data packets are successfully transmitted.

8. The method for conflict resolution of a communication system based on slotted ALOHA and NOMA according to claim 7, wherein In step S604, determining the change of corresponding parameters according to different feedbacks includes: Feedback e indicates that a collision occurs in this time slot. The current allocation interval is evenly divided into L and R sets, and the L set is transmitted in the next time slot. The lower threshold remains unchanged, and the length of the allocation interval is reduced to half of the original; Feedback 1. L represents the set L of successful transmissions in this time slot. The corresponding set R needs to be transmitted in the next time slot. The lower threshold is updated to , which refers to the length of the allocation interval and remains unchanged; Feedback 0, L indicates that the L set has been transmitted in this time slot and it is found that the L set is an empty set. At this time, in the next time slot, the R set will not be decomposed into L and R sets again, and a new L set will be transmitted in the next time slot. The lower threshold is updated to , and the length of the assigned interval is reduced to half of the original; Assigned interval length Directly update to .

9. A communication system conflict resolution system based on slotted ALOHA and NOMA, characterized in that, It includes: A construction module that constructs a communication system model that combines slotted ALOHA and NOMA. The communication system model includes the unlicensed random access of N users; The allocation module accesses the network formed by the communication system model with N user nodes in the construction module according to the allocated new packet transmission power levels, and moves the collided data packets into the collision queue; Synchronization module, based on the FCFS algorithm, synchronizes and decomposes the collision queue obtained by the allocation module, specifically: The difference between the moment of obtaining collision feedback and the arrival moment of the data packet in extreme cases , that is, the difference between the moment of obtaining feedback and the arrival moment of all data packets in the corresponding time slots is less than . The arrival moment of the collision queue is delayed by based on the moment of the original arrival communication system model, and then conflict resolution is performed; Set the initial allocation interval length to , initialize the time when conflict resolution is completed , initialize the lower threshold of the allocation interval , the L set and R set are used to store data packets, and record the current slot number as ; The allocation interval length of the first time slot is defined as , and packets arriving at a time within are transmitted at an arbitrary power level among the allocated power levels at the start time of the th time slot. After decoding using NOMA technology, the collision queue is updated; At the end of the time slot, the time slot sequence number is shifted one position backward. The feedback information obtained by the communication system model is (0, 1, e). 0 indicates that the time slot is empty and no data packet is transmitted. 1 represents that the data packet in the time slot is successfully transmitted. e indicates that a collision occurs in the time slot. The communication system model obtains the feedback that the data transmitted in this time slot is from set L or set R; Determine the changes in corresponding parameters according to different feedbacks, and determine the data packets to be transmitted in the next time slot; Repeat the above steps until the time slot number ; Recording module, which saves the collision queue that has not been decomposed after the synchronization module ends, and records the feedback information (0, 1, e) and the R set and L set after the end of the Mth time slot; Update module, which updates the time slot sequence number according to the feedback information (0, 1, e) obtained by the recording module, the R set, and the L set , the lower threshold of the decomposition interval and the collision queue; Decomposition module, based on the FCFS algorithm, decomposes the collision queue obtained by the update module until all data packets are successfully transmitted.

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