Method for acquiring total number of users capable of successfully serving in space-air-ground integrated network

Abstract

The invention provides a method for acquiring the total number of users capable of successfully serving in an air-space-ground integrated network. The method comprises the following steps: constructing a communication system model between a low earth orbit LEO satellite and a ground user in a space-air-ground integrated network SAGIN, and calculating path loss, receiving power and data transmission rate of a link in the communication system model; constructing an objective function of access time slot scheduling and backhaul bandwidth allocation in the communication system model with the purpose of maximizing the number of successful service users; and under the condition that the access time slot number and the return bandwidth are limited, solving the target function by adopting a resource scheduling algorithm for maximizing the number of successfully served users, and obtaining the total number of the successfully served users. According to the invention, an access and return integrated resource scheduling scheme is designed, so that resources such as bandwidth and time slot of each link can be reasonably allocated under different network conditions, the QoS (Quality of Service) requirement of a user is met, and the overall performance of the system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of network resource scheduling, and particularly relates to a method for access time slot scheduling and backhaul bandwidth allocation in a SAGIN (Space-Air-Ground Integrated Network). Background Technique

[0002] In the existing resource scheduling methods in SAGIN, the main focus is on how to optimize performance metrics such as the energy consumption of the system, and consider how to improve the transmission rate of the system. In terms of resource allocation, a method of cooperative power allocation has been proposed to optimize the power control of the entire network, thereby achieving the purpose of enhancing the system capacity. There are solutions that study the problem of maximizing energy efficiency in SAGIN. By jointly optimizing sub-channel allocation and terminal transmission power control, their methods perform excellently in terms of energy efficiency. There are also solutions that develop a content service-oriented resource allocation method for the SAGIN 6G network, using three-party cyclic matching, and this method performs well in terms of system throughput and user satisfaction. There are also solutions that study the reasonable range of the transmission probability of the ground-air-space link with the goal of maximizing system throughput, and study the problem of maximizing the total amount of data received by the data processing center within a given time range based on the time-expanded graph.

[0003] Regarding the flow scheduling problem in the SAGIN scenario, several solutions have been proposed in the early research results. However, in the SAGIN scenario, how to comprehensively consider system resource constraints and design a comprehensive scheduling strategy remains an open and challenging topic. There is a solution that proposes a heuristic algorithm in the millimeter-wave network, aiming to improve system throughput by increasing the number of scheduled flows. In this algorithm, if scheduling an additional flow can improve system throughput, then this flow will be scheduled preferentially. There is also a solution that proposes a scheduling algorithm based on the maximum QoS (Quality of Service) awareness independent set, aiming to increase the number of flow schedules while reducing signal interference, and optimizing resource utilization and system performance. There is also a solution that proposes a QoS-aware scheduling scheme for the blocking problem in the millimeter-wave backhaul network, ensuring that the number of flow schedules and system throughput remain at a high level under limited resources. There is also a solution that proposes a coalition game algorithm to solve the user association and transmission scheduling problems in the millimeter-wave train-ground communication system with MR (Measurement Report), aiming to improve the total rate of the network and the dynamic adaptability of the system in the mobile scenario. There is also a solution that proposes a drone-assisted high-speed rail millimeter-wave communication scheme, aiming to optimize the throughput and stability of the high-speed rail communication system by maximizing the number of scheduled flows and ensuring that the QoS requirements of the high-speed rail system are met at the same time.

[0004] At present, the research on resource scheduling methods in the SAGIN multi-segment scenario rarely involves how to maximize the number of successfully served users in the system through reasonable resource allocation. Some solutions have proposed two fairness optimization strategies for different network loads: resource allocation and resource auction, aiming to maximize the data rate required by users. There are also solutions that optimize the association control and bandwidth allocation problems in SAGIN with the goal of minimizing the task waiting time.

[0005] The disadvantages of the existing SAGIN multi-segment scenario resource scheduling methods in the above-mentioned prior art include:

[0006] In the HAP (High Altitude Platforms) assisted SAGIN communication system, the existing research still has deficiencies in the scheduling of various system resources such as time and bandwidth. Future research needs to explore how to jointly optimize multiple resources, especially taking into account the QoS requirements of different users. In this context, how to dynamically allocate resources according to user needs and ensure coordinated scheduling between links will be a key research topic.

[0007] In the SAGIN scenario, how to improve the scheduling efficiency of data streams in the communication system without sacrificing user QoS is still an urgent and challenging issue to be solved. In the SAGIN communication system, the existing research still lacks in-depth discussion on the coordinated scheduling of resources in different segments. Future research should focus on the comprehensive optimization of multiple segments (air, ground, space), especially on the resource scheduling coordination problem between the access link and the backhaul link. How to achieve efficient resource allocation and scheduling between the access link and the backhaul link to ensure load balancing and communication quality between segments will be a key research direction. Summary of the Invention

[0008] Embodiments of the present invention provide a method for access slot scheduling and backhaul bandwidth allocation in SAGIN to effectively improve the overall performance and resource utilization rate of the SAGIN communication system.

[0009] To achieve the above object, the present invention adopts the following technical solutions.

[0010] A method for obtaining the total number of users that can be successfully served in an integrated space-air-ground network, including:

[0011] Construct a communication system model between low Earth orbit (LEO) satellites and ground users in the integrated space-air-ground network SAGIN, and calculate the path loss, received power, and data transmission rate of the links in the communication system model;

[0012] Construct the objective function for access slot scheduling and backhaul bandwidth allocation in the communication system model with the aim of maximizing the number of successfully served users;

[0013] Under the condition of limited access slots and backhaul bandwidth, use the resource scheduling algorithm of maximizing the number of successfully served users to solve the objective function and obtain the total number of users that can be successfully served.

[0014] Preferably, the construction of the communication system model between LEO satellites and ground users in SAGIN, and the calculation of the path loss, received power and data transmission rate of the links in the communication system model include:

[0015] Set the height of the LEO satellite as h1, the high-altitude platform HAP is deployed within the coverage area of the LEO satellite with a height of h2, and the ground user UE is distributed within the coverage ranges of the LEO satellite and the HAP. Each superframe is divided into M equal-length time slots, and one communication link is scheduled within each time slot. The spectrum is divided into N equal-length frequency bands, and different communication links use different frequency bands for transmission;

[0016] When the UE has a communication request, an access link l1 is formed: LEO satellite → UE or HAP → UE; when the HAP has a communication request, a backhaul link l2 is formed: LEO satellite → HAP. For the link l, the path loss P l L is:

[0017] P l L = 20lgf l (MHz)+10ρlgd l (km)+A(ρ), (1)

[0018] where f l represents the operating frequency, d l represents the distance between the transmitter and the receiver, ρ is the path loss exponent, A(ρ) is a constant value for a given ρ, and the received power P l re of the link l is expressed as:

[0019]

[0020] where P l tr represents the transmit power of the link l, and represent the antenna gains of the transmitter and receiver respectively. According to Shannon's channel capacity formula, the data transmission rate R l of the link l is expressed as:

[0021]

[0022] where η ∈ (0, 1) is the transceiver communication efficiency, W l is the bandwidth of link l, and N0 is the one-sided noise power spectral density of the Gaussian channel;

[0023] Assume that the number of time slots allocated to link l is T l , then the throughput q of link l l is expressed as:

[0024]

[0025] Preferably, the objective function for constructing the access time slot scheduling and backhaul bandwidth allocation in the communication system model for the purpose of maximizing the number of successfully served users includes:

[0026] Set the set of terrestrial users to be represented as The set of LEO satellites to be represented as where the LEO satellite is represented as n = 0, and the set of HAPs is represented as For the access network where terrestrial users access HAPs or LEO satellites, design an access scheduling scheme with M transmission time slots. For the backhaul network between LEO satellites and each HAP, design a backhaul scheduling scheme within the spectral window with N transmission frequency bands;

[0027] Terrestrial users access HAPs or LEO satellites through access link l1. The transmitter is represented as n, and the receiver is represented as u. Define a binary variable indicating whether access link l1 is scheduled within time slot t. If so, otherwise,

[0028] Within one time slot, a user can only choose to connect to a LEO satellite or a certain HAP. Within one time slot, a LEO satellite or a HAP can schedule at most one link. The binary variable satisfies the following conditions:

[0029]

[0030] According to formula (3), for access link l1, the achievable data rate of transmitter n at receiver u is expressed as

[0031]

[0032] Let the QoS requirement of user u be Q u , define indicating the number of time slots actually allocated to user u, specifically expressed as

[0033]

[0034] Among them, In the access network, the number of time slots included in a time frame is M, It is necessary to satisfy:

[0035]

[0036] According to formula (4), for the access link l1, the throughput of user u is expressed as

[0037]

[0038] For the backhaul link l2 between the LEO satellite and each HAP, the transmitter is expressed as n = 0, and the receiver is expressed as For each user u, the allocated backhaul bandwidth is expressed as

[0039] According to formula (3), for the backhaul link l2 of user u, the data rate at the receiver when the transmitter n = 0 is expressed as: at the receiver is expressed as:

[0040]

[0041] The bandwidth allocated to each user in the backhaul network cannot exceed the maximum bandwidth limit W, which is specifically expressed as:

[0042]

[0043] For the data sent through the HAP using the relay mode, it is necessary to ensure that the backhaul link of the HAP provides sufficient rate support for all users associated with this HAP, which is specifically expressed as:

[0044]

[0045] Define a binary variable I u to represent whether user u meets the QoS requirements. If it meets, the flag bit of this user is set to 1, that is:

[0046]

[0047] With the aim of maximizing the number of successfully served users, the objective function P1 for access slot scheduling and backhaul bandwidth allocation in the communication system model is constructed;

[0048]

[0049] Preferably, in the case of limited access slots and backhaul bandwidth, the resource scheduling algorithm of maximizing the number of successfully served users is adopted to solve the objective function, and the total number of users that can be successfully served is obtained, including:

[0050] The input data of the resource scheduling algorithm for maximizing the number of successfully served users includes U users, N HAPs, the positions of LEO satellites, and the QoS requirements of each user. The access scheduling part of the resource scheduling algorithm for maximizing the number of successfully served users preferentially allocates resources to users with fewer required time slots. According to formula (14), the number of transmission time slots actually allocated to the access link is The smaller the value of, the fewer time slots the user is allocated. Select as the user association criterion for the access link, which is simplified as Q / R. The access scheduling decision is summarized as the transmitting HAP or LEO satellite preferentially selecting a user with a smaller Q / R and associating with it. After the access link scheduling is completed, frequency resource allocation is performed on the backhaul link of the associated user. Under the constraint of formula (18), a user requiring the least backhaul bandwidth is preferentially selected for priority allocation. The backhaul bandwidth allocated to each HAP is based on the QoS of the users associated with it on the access link. The backhaul link of the HAP must ensure sufficient rate support for all users associated with this HAP. According to the allocation result of the backhaul link resources, users that are not successfully scheduled are dissociated from their access links, and their access time slots are restored. The output data of the resource scheduling algorithm for maximizing the number of successfully served users is the number of successfully served users;

[0051]

[0052]

[0053] As can be seen from the technical solutions provided by the embodiments of the present invention above, the present invention designs an integrated access and backhaul resource scheduling scheme, thereby ensuring that resources such as bandwidth and time slots of each link can be reasonably allocated under different network conditions to meet the QoS requirements of users and improve the overall performance of the system.

[0054] Additional aspects and advantages of the present invention will be given in part in the following description, and these will become apparent from the following description or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0056] Figure 1 It is a processing flowchart of a method for access time slot scheduling and backhaul bandwidth allocation in a SAGIN provided by an embodiment of the present invention;

[0057] Figure 2 This is a structural diagram of a communication system considering the communication between LEO satellites and ground users in SAGIN provided by an embodiment of the present invention;

[0058] Figure 3 This is a superframe structure diagram provided by an embodiment of the present invention;

[0059] Figure 4 This is a spectrum structure diagram provided by an embodiment of the present invention. Detailed implementation manners

[0060] The following details the implementation manners of the present invention. Examples of the implementation manners are shown in the accompanying drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The implementation manners described below by referring to the accompanying drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0061] Those skilled in the art of the present technology can understand that unless specifically stated, the singular forms "a", "an", "the", and "said" used herein may also include the plural forms. It should be further understood that the term "including" used in the specification of the present invention means the presence of the described features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or their groups. It should be understood that when an element is "connected" or "coupled" to another element, it can be directly connected or coupled to other elements, or there may also be intermediate elements. In addition, the "connection" or "coupling" used herein may include wireless connection or coupling. The phrase "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0062] Those skilled in the art of the present technology can understand that unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as the general understanding of those of ordinary skill in the art to which the present invention belongs. It should also be understood that terms such as those defined in a general dictionary should be understood to have a meaning consistent with the meaning in the context of the prior art and will not be interpreted with an idealized or overly formal meaning unless defined as herein.

[0063] For ease of understanding of the embodiments of the present invention, the following will further explain with several specific embodiments by referring to the accompanying drawings, and each embodiment does not constitute a limitation on the embodiments of the present invention.

[0064] An access time slot scheduling and backhaul bandwidth allocation method in SAGIN is proposed in an embodiment of the present invention. This method can coordinately allocate resources such as time and bandwidth according to user requirements and system status. The present invention aims to develop a more intelligent and highly adaptable flow scheduling algorithm that can respond in real time and adjust resource allocation strategies in a complex and changeable network environment, ensuring that the SAGIN communication system can provide efficient and stable services under different operating conditions, thereby achieving reliable communication quality and maximizing system performance.

[0065] The resource scheduling algorithm for maximizing the number of successfully served users proposed in the present invention preferentially selects the users with the minimum time slot requirements associated with the HAP or LEO satellite, and calculates and allocates the actual number of access time slots on the premise of meeting the user QoS requirements. Each user can only be associated with a certain HAP or LEO (Low Earth Orbit) satellite to avoid repeated associations and ensure the efficient use of system resources. After the access link scheduling is completed, the algorithm allocates the bandwidth of the backhaul link according to the access QoS requirements of each user, and preferentially considers the users with less demand for resource allocation. During the backhaul link resource allocation process, for the users that are not successfully scheduled, the association with the access link is released and their access time slots are restored to provide opportunities for other users. Through this series of scheduling operations, the algorithm can maximize the number of users successfully served in the system under limited resource conditions, and improve the overall system performance and service quality.

[0066] The processing flow chart of an access time slot scheduling and backhaul bandwidth allocation method in SAGIN provided by an embodiment of the present invention is as Figure 1 shown, including the following processing steps;

[0067] Step S10: Construct a communication system model between LEO satellites and ground users in SAGIN, and calculate the path loss, received power, and data transmission rate of the links in the above communication system model.

[0068] Step S20: With the aim of maximizing the number of successfully served users, construct an objective function for access time slot scheduling and backhaul bandwidth allocation in the communication system model.

[0069] Step S30: Use the resource scheduling algorithm for maximizing the number of successfully served users based on Q / R to solve the above objective function and obtain the total number of users that can be successfully served.

[0070] Specifically, the above step S10 includes: The structure of the communication system model considering the LEO satellite and ground users in SAGIN proposed in an embodiment of the present invention is as Figure 2As shown in the figure. The altitude of the LEO satellite is h1, the HAP is deployed within the coverage area of the LEO satellite with an altitude of h2, and ground users such as mobile phone users, vehicles, and maritime vessels are evenly distributed within the coverage ranges of the LEO satellite and the HAP. When the satellite has data to transmit to ground users, it can directly send the data to the users through a direct link, using the communication frequency band C band f1, or relay the data to the target users through the HAP, that is, the satellite first sends the data to the HAP using the millimeter wave frequency band f2, and then the HAP forwards the data to the ground users using the C band f1. The main problem solved by the present invention is the downlink data transmission scheduling problem between the LEO satellite and ground users.

[0071] During the process of ground users receiving data sent by the LEO satellite or the HAP, a Time Division Multiple Access (TDMA) method is adopted for signal access and data reception. Time is divided into a series of superframes. Figure 3 This is a superframe structure diagram provided by an embodiment of the present invention, as Figure 3 shown. Each superframe consists of a scheduling stage and a transmission stage. The scheduling stage is responsible for collecting link requests from the sending end. In the transmission stage, the superframe is further divided into M equal-length time slots, and each time slot can be used to transmit data. Since both the transmitter and the receiver are equipped with single antennas, only one communication link can be scheduled within each time slot.

[0072] During the process of the HAP receiving data sent by the LEO satellite, a Frequency Division Multiple Access (FDMA) method is adopted to achieve spectrum resource allocation and data reception. Figure 4 This is a spectrum structure diagram provided by an embodiment of the present invention. The spectrum is divided into N equal-length frequency bands, as Figure 4 shown. Different communication links use different frequency bands for transmission.

[0073] In the present invention, there are three communication nodes: the LEO satellite, the HAP, and ground users. Link l represents the actual connection for direct communication between two communication nodes. There are three communication links in this system. When the UE has a communication request, an access link l1 (LEO satellite → UE or HAP → UE) is formed. When the HAP has a communication request, a backhaul link l2 (LEO satellite → HAP) is formed. The present invention adopts a Line of Sight (LoS) loss model to achieve highly directional transmission. According to the path loss model, for link l, the path loss P l L is:

[0074] P l L= 20lgf l (MHz) + 10ρlgd l (km) + A(ρ), (1)

[0075] where f l represents the operating frequency. d l represents the distance between the transmitter and the receiver. ρ is the path loss exponent, and A(ρ) is a constant value for a given ρ. The received power P of link l l re can be expressed as:

[0076]

[0077] where P l tr represents the transmit power of link l. and represent the antenna gains at the transmitter and receiver ends respectively. According to Shannon's channel capacity formula, the data transmission rate R of link l l can be expressed as:

[0078]

[0079] where η ∈ (0,1) is the transceiver communication efficiency. W l is the bandwidth of link l. N0 is the one-sided noise power spectral density of the Gaussian channel.

[0080] Assume the number of time slots allocated to link l is T l , then the throughput q that link l can achieve l is expressed as

[0081]

[0082] When a terrestrial user receives data sent by a LEO satellite or a HAP, the present invention considers using a directional antenna. When the frequency range is from 1 GHz to 70 GHz, the antenna gain is expressed as:

[0083]

[0084] where is the off-axis angle. G m is the maximum antenna gain. D is the antenna diameter. λ is the wavelength. G1 is the first side lobe gain. are calculated respectively as:

[0085]

[0086] G1 = 12.02(D / λ) -0.6 . (7)

[0087] When the HAP receives data sent by the LEO satellite, a millimeter-wave directional antenna model is considered. The antenna gain of the directional antenna model can be expressed as:

[0088]

[0089] where θ is the off-axis angle. θ ml =-2.6·θ -3dB is the main lobe width. θ -3dB is the angle of the half-power beam width. The maximum antenna gain G m and the sidelobe gain G sl can be expressed as:

[0090] G m =10log 10 (1.6162sin(θ -3dB / 2)) 2 (9)

[0091] G sl =-0.4111log(θ -3dB )-10.579 (10)

[0092] Specifically, the above step S20 includes: In the present invention, the resource scheduling problem between the LEO satellite and the ground user will be considered. The HAP acts as a relay for auxiliary data transmission. In the present invention, the set of ground users is represented as The set of LEO satellites is represented as where the LEO satellite is represented as n = 0, and the set of HAPs is represented as For the access network where the ground user accesses the HAP or the LEO satellite, an access scheduling scheme with M transmission time slots is designed. For the backhaul network between the LEO satellite and each HAP, a backhaul scheduling scheme within the spectral window with N transmission frequency bands is designed.

[0093] The ground user accesses the HAP or the LEO satellite through the access link l1. The sender is represented as n, and the receiver is represented as u. A binary variable is defined indicating whether the access link l1 is scheduled within the time slot t. If so, Otherwise,

[0094] Within one time slot, the user can only select to connect to the LEO satellite or a certain HAP. Within one time slot, the LEO satellite or the HAP can schedule at most one link. Then the binary variable needs to satisfy the following conditions:

[0095]

[0096] According to Equation (3), for the access link l1, the achievable data rate of the sender n at the receiver u can be expressed as:

[0097]

[0098] Each user u has a QoS requirement Q u . When the number of time slots allocated to a user is greater than the number of time slots required by the user, the throughput that the user can achieve is greater than the throughput it requires. Therefore, the number of access transmission time slots initially allocated to each user is rounded up from the number of access transmission time slots it requires. The number of access transmission time slots required by a user is equal to the ratio of the total amount of data to be transmitted to the transmission rate. Define to represent the number of time slots actually allocated to user u, specifically expressed as:

[0099]

[0100] where in the access network, the number of time slots contained in a time frame is M, which needs to satisfy:

[0101]

[0102] According to Equation (4), for the access link l1, the actual achievable throughput of user u can be expressed as:

[0103]

[0104] For the backhaul link l2 between the LEO satellite and each HAP, the sender is represented as n = 0, and the receiver is represented as For each user u, the allocated backhaul bandwidth is represented as In the present invention, in order to allocate backhaul resources more effectively, the allocation of the backhaul bandwidth changes dynamically with the state of the access link.

[0105] According to Equation (3), for the backhaul link l2 of user u, the achievable data rate of the sender n = 0 at the receiver can be expressed as:

[0106]

[0107] The bandwidth allocated to each user in the backhaul network cannot exceed the maximum bandwidth limit W, specifically expressed as:

[0108]

[0109] For the data sent through the HAP in relay mode, it is necessary to ensure that the backhaul link of the HAP provides sufficient rate support for all users associated with this HAP, specifically expressed as:

[0110]

[0111] The goal of the present invention is to enable the maximum number of users to meet the QoS requirements within a specified time frame and bandwidth. A binary variable I is defined u to indicate whether user u meets the QoS requirements. If it meets, the flag bit of this user is set to 1, that is

[0112]

[0113] Therefore, the proposed problem of maximizing the number of served users can be modeled as (P1)

[0114]

[0115] Specifically, the above step S30 includes: Problem P1 is to maximize the number of successfully served users under the condition of limited access time slots and backhaul bandwidth. If user u is associated with the HAP or LEO satellite, then according to formula (14), the number of transmission time slots actually allocated to this access link is It can be seen that the smaller the value of, the fewer time slots the user is allocated. Therefore, the present invention selects as the user association criterion for the access link, which is simplified as Q / R. For the backhaul link between the LEO satellite and each HAP, the backhaul bandwidth allocated to each HAP is based on the QoS of the users associated with it on the access link. Specifically, the backhaul link of the HAP should ensure sufficient rate support for all users associated with this HAP.

[0116] Based on the above constraints, the present invention proposes a resource scheduling algorithm for maximizing the number of successfully served users based on Q / R. The input of this algorithm includes U users, N HAPs, and the positions of the LEO satellite and the QoS requirements of each user. The output of the algorithm is the access resource scheduling and backhaul resource allocation results. Line 1 requires that the users, HAPs, and LEO satellite are currently still available. Line 2 indicates that steps 3 - 11 are executed on the associable HAPs and LEO satellites. Lines 3 - 4 are that the transmitting HAP or LEO satellite preferentially selects users with a smaller Q / R and associates with them. Line 5 adds the selected users to the user set of n . Line 6 calculates the number of time slots actually allocated to user u Under the condition of satisfying (15), the scheduling variable between the transmitting end n and user u Set 1. Due to the constraint of (11), each user can only be associated with a certain HAP or LEO satellite. To avoid duplicate associations, exclude the already associated users from the set of users that can be associated, as shown in line 8. When (15) is no longer satisfied, dissociate the current n from user u, exclude n from the associable set and the user is no longer associated with this n, as shown in line 10. Loop the operations in lines 2 - 12 until the condition in line 1 is not satisfied, and the user association and access resource scheduling pre - decision are completed.

[0117] After the access link scheduling is completed, frequency resource allocation is performed on the backhaul links of the associated users. In line 16, the bandwidth allocated to the backhaul link is calculated according to the access QoS of each associated user. In lines 21 - 22, due to the limited backhaul bandwidth resources, under the constraint of (18), the users that require the least backhaul bandwidth are preferentially selected for priority allocation. Finally, in line 23, according to the allocation result of the backhaul link resources, the users whose backhaul is not successfully scheduled are dissociated from their access links, and their access time slots are restored.

[0118]

[0119]

[0120] Regarding the complexity of the resource scheduling algorithm for maximizing the number of successfully served users, it is mainly affected by the number of HAPs and users. Considering the worst - case scenario, the algorithm traverses the HAPs and all users. In this case, the computational complexity is and its complexity is not high.

[0121] In summary, the present invention proposes a QoS - aware integrated access - backhaul resource scheduling strategy for the SAGIN communication system, aiming to maximize the number of successfully served users and the system throughput. To achieve this goal, the present invention first establishes a system model and a channel model based on the actual characteristics of the SAGIN communication system to ensure that the network resource allocation and transmission environment can be accurately described. Subsequently, an optimization problem model is constructed, focusing on maximizing the number of successfully served users, and through an effective resource allocation strategy, the limited communication resources are fully utilized. Further, the present invention proposes a data transmission path selection algorithm, which combines an intelligent decision - making mechanism to select the optimal data transmission path in each time slot, ensuring both the QoS requirements of the requested flows and maximizing the number of successfully scheduled flows. The implementation of this scheduling strategy not only significantly improves the overall performance and resource utilization rate of the SAGIN communication system, optimizes the user experience, but also provides a new theoretical basis and solution for the resource management of communication systems in future multi - user and limited - resource environments.

[0122] Those of ordinary skill in the art can understand that the accompanying drawings are only schematic diagrams of an embodiment, and the modules or processes in the accompanying drawings are not necessarily essential for implementing the present invention.

[0123] From the description of the above embodiments, those skilled in the art can clearly understand that the present invention can be implemented by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of the present invention, in essence, or the part that makes a contribution to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of the present invention.

[0124] Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the device or system embodiments, since they are basically similar to the method embodiments, the description is relatively simple. For the relevant parts, reference can be made to the description of the method embodiments. The device and system embodiments described above are only illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative efforts.

[0125] As mentioned above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for obtaining the total number of users that can be successfully served in an air-ground integrated network, characterized in that: include: Construct a communication system model between low earth orbit (LEO) satellites and ground users in the space-ground integrated network SAGIN, and calculate the path loss, received power and data transmission rate of the links in the communication system model; To maximize the number of successfully served users, construct an objective function of access time slot scheduling and backhaul bandwidth allocation in the communication system model; In the case where the number of access time slots and the backhaul bandwidth are limited, a resource scheduling algorithm for maximizing the number of successfully served users is used to solve the objective function and obtain the total number of users that can be successfully served.

2. The method according to claim 1, characterized in that The construction of the communication system model between the LEO satellite and the ground user in SAGIN and the calculation of the path loss, receiving power and data transmission rate of the link in the communication system model include: Set the LEO satellite height to h1, the high-altitude platform HAP is deployed in the coverage area of ​​the LEO satellite at a height of h2, and the ground user UE is distributed in the coverage area of ​​the LEO satellite and HAP. Each superframe is divided into M equal-length time slots, and a communication link is scheduled in each time slot. The spectrum is divided into N equal-length frequency bands, and different communication links use different frequency bands for transmission; When the UE has a communication request, an access link l1 is formed: LEO satellite → UE or HAP → UE; when the HAP has a communication request, a backhaul link l2 is formed: LEO satellite → HAP. For link l, the path loss P between the transmitter and the receiver is l L for: P.S l L 20lgf l (MHz)+10ρlgd l (km)+A(ρ), (1) where f l represents the operating frequency, d l represents the distance between the transmitter and the receiver, ρ is the path loss exponent, A(ρ) is a constant value for a given ρ, and the received power P of link l l re It is expressed as: Where P l tr represents the transmission power of link l, and Represent the antenna gains of the transmitter and receiver respectively. According to Shannon's channel capacity formula, the data transmission rate R of link l l It is expressed as: Among them, η∈(0,1) is the transceiver communication efficiency, W l is the bandwidth of link l, N0 is the power spectral density of the unilateral noise of the Gaussian channel; Assume that the number of time slots allocated to link l is T l , then the throughput of link l is q l It is expressed as:

3. The method according to claim 2, characterized in that The objective function of access time slot scheduling and backhaul bandwidth allocation in the communication system model is constructed for the purpose of maximizing the number of successfully served users, including: Set the set of ground users to be represented as The collection of LEO satellites is represented as The LEO satellite is represented by n=0, and the set of HAPs is represented by For the access network of ground users accessing HAP or LEO satellite, an access scheduling scheme with M transmission time slots is designed. For the backhaul network between LEO satellite and each HAP, a backhaul scheduling scheme within a spectrum window with N transmission frequency bands is designed. Ground users access HAP or LEO satellites through access link l1. The transmitter is represented by n and the receiver is represented by u. Define a binary variable Indicates whether access link l1 is scheduled in time slot t. If yes, otherwise, In a time slot, the user can only choose to connect to a LEO satellite or a HAP. In a time slot, a LEO satellite or a HAP can schedule at most one link. The following conditions are met: According to formula (3), for access link l1, the realized data rate of transmitter n at receiver u is expressed as Assume that the QoS requirement of user u is Q u ,definition It represents the number of time slots actually allocated to user u, which is specifically expressed as in, In the access network, a time frame contains M time slots. Need to meet: According to formula (4), for access link l1, the throughput of user u is expressed as For the return link l2 between the LEO satellite and each HAP, the sending end is represented by n=0 and the receiving end is represented by For each user u, the allocated backhaul bandwidth is expressed as According to formula (3), for the return link l2 of user u, the sending end n = 0 at the receiving end The data rate at is expressed as: The bandwidth allocated to each user in the backhaul network cannot exceed the maximum bandwidth limit W, which is specifically expressed as: For data sent through a HAP using relay mode, it is necessary to ensure that the HAP's backhaul link provides sufficient rate support for all users associated with this HAP, as shown in the following figure: Define a binary variable I u To indicate whether user u meets the QoS requirements, if so, the flag bit of this user is set to 1, that is: To maximize the number of successfully served users, the objective function of access time slot scheduling and backhaul bandwidth allocation in the communication system model is constructed as P1; 4. The method according to claim 3, characterized in that The objective function is solved by using a resource scheduling algorithm for maximizing the number of successfully served users to obtain the total number of users that can be successfully served when the number of access time slots and the backhaul bandwidth are limited, including: The input data of the resource scheduling algorithm for maximizing the number of successfully served users includes U users, N HAPs, the position of the LEO satellite and the QoS requirement of each user. The access scheduling part of the resource scheduling algorithm for maximizing the number of successfully served users preferentially allocates resources to users with a small number of required time slots. According to formula (14), the number of transmission time slots actually allocated to the access link is Q u / The smaller the value of, the fewer time slots the user is allocated. u / As the user association criterion of the access link, it is simplified to Q / R. The access scheduling decision is summarized as the transmitting end HAP or LEO satellite preferentially selects the user with smaller Q / R and associates with it. After the access link scheduling is completed, frequency resource allocation is performed on the backhaul link of the associated user. Under the constraint of formula (18), the user who needs the least backhaul bandwidth is preferentially selected for priority allocation. The backhaul bandwidth allocated to each HAP is based on the QoS of the user associated with it on the access link. The backhaul link of the HAP must ensure that sufficient rate support is provided for all users associated with this HAP. According to the allocation result of the backhaul link resources, the user whose backhaul is not successfully scheduled is disassociated from its access link, and its access time slot is restored. The output data of the resource scheduling algorithm for maximizing the number of successfully served users is the number of successfully served users.

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