Unmanned aerial vehicle air base station hovering site selection method based on Stackelberg game

Abstract

The invention discloses an unmanned aerial vehicle air base station hovering site selection method based on a Stackelberg game. The method comprises the following steps: step 1, an air base station randomly selects a position for hovering and collects a minimum data transmission rate demand value of a user in a network and a maximum total channel gain value of the air base station to a user set # imgabs0 # in a three-dimensional space; step 2, the air base station adopts a Stackelberg game mechanism to make a decision for the optimal channel gain information of each user of the user set # imgabs1 #; 3, the air base station forms a three-dimensional channel gain equal-height body for each user according to the optimal channel gain information of the users and the position information of each user, and if the three-dimensional channel gain equal-height bodies of all the users in the user set # imgabs2 have a common intersection, the three-dimensional channel gain equal-height bodies of all the users in the user set # imgabs2 have a common intersection; if yes, the air base station can perform random site selection in the intersection and hover in the air; otherwise, deleting the users with the least intersection with the three-dimensional channel gain equal-height bodies of the other users in the user set # imgabs3 #, and if a plurality of the users exist, deleting the users with the minimum coverage volume of the three-dimensional channel gain equal-height bodies of the users, and returning to the step 2. According to the method, a scene without base station service caused by natural disasters and the like of a plurality of users in the same area is considered, so that the problem of hovering site selection of the air base station of the temporary unmanned aerial vehicle is solved, and the method physically conforms to a scene of practical application and can be effectively applied to engineering practice.

Description

Technical Field

[0001] The present invention relates to the technical field of aerial base stations in wireless communications, and in particular to a hovering site selection method for an aerial base station of an unmanned aerial vehicle based on Stackelberg game. Background Art

[0002] In wireless networks, traditional ground base stations are affected by factors such as geographical conditions and building obstructions, making it difficult to achieve wide-area coverage without dead angles. Especially in remote areas, mountainous areas, oceans and other areas, the construction of communication infrastructure is costly and difficult, resulting in insufficient network coverage. In particular, when natural disasters (such as earthquakes, typhoons and freezing rain, etc.) occur, the traditional fixed base stations on the ground will be missing, thus affecting the signal transmission of surrounding users. Aerial base stations can cover a wider area, reduce the number of ground base stations deployed, and improve the breadth and depth of network coverage. This helps to solve the communication problems in remote areas, mountainous areas, oceans and other areas, and provide users with more stable and reliable network services. Compared with traditional base stations, aerial base stations do not require complex infrastructure construction and can build temporary communication networks in a short time. This is particularly important in emergency situations such as natural disasters and emergencies, and can quickly restore communications to ensure the smooth progress of rescue operations. At the same time, aerial base stations can be flexibly adjusted and optimized according to actual needs, such as adjusting flight altitude, coverage, etc., to adapt to different communication needs and environmental changes. Summary of the invention

[0003] Purpose of the invention: The present invention provides a hovering site selection method for an aerial base station of a UAV based on Stackelberg game to solve the problem of location selection of an aerial base station serving multiple users in three-dimensional space.

[0004] Technical solution: The method for selecting a hovering site for a UAV aerial base station based on Stackelberg game described in the present invention comprises the following steps:

[0005] Step 1: The aerial base station randomly selects a location to hover and collects the minimum data transmission rate requirements of users in the network and the aerial base station's requests for user sets in three-dimensional space. The maximum total channel gain value;

[0006] Step 2: The air base station uses the Stackelberg game mechanism to collect user Make decisions based on the optimal channel gain information of each user;

[0007] Step 3: The aerial base station forms a three-dimensional channel gain contour for each user based on the user's optimal channel gain information and the location information of each user. If the three-dimensional channel gain contours of all users in the user set have a common intersection, then the aerial base station can be randomly selected in the above intersection and hover in the air; otherwise, the user set Delete the user whose three-dimensional channel gain contour body intersection with other users is the smallest. If there are several such users, delete the user whose three-dimensional channel gain contour body coverage volume is the smallest, and return to step 2.

[0008] Furthermore, in step 2, in the game, the aerial base station, as the leader of the two parties in the game, sells limited channel gain resources, and the users, as the buyers in the game, obtain benefits by purchasing limited channel gain resources.

[0009] Furthermore, the seller utility function in the game model is defined as the total revenue paid by all users to the air base station for purchasing limited channel gain resources.

[0010] Furthermore, the utility function of the buyer in the game model is defined as the difference between the game benefit of each user's data transmission rate and the game cost of purchasing the channel gain of the air base station, which is in: is the average power value allocated by the air base station to the user for its downlink data transmission, σ 2 is the noise at the user receiver, h m is the channel gain from the air base station to user m, and β is the unit resource pricing.

[0011] Further, in step 3, according to the optimal The three-dimensional channel gain contour of the user can be obtained, in which the channel gain from the aerial base station to user m is equal to

[0012] Furthermore, through the user collection Whether multiple rounds of games are needed is determined by whether the three-dimensional channel gain contours of all users in have a common intersection. If there is no common intersection, multiple rounds of games are started.

[0013] Furthermore, in the initialization phase of the multi-round game, the user set Delete the user whose three-dimensional channel gain contour body intersection with other users is the smallest. If there are several such users, delete the user whose three-dimensional channel gain contour body volume is the smallest.

[0014] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The present invention takes into account the scenario where multiple users are without base station services in the same area due to natural disasters and other reasons, so as to solve the problem of temporary drone aerial base station hovering site selection, which physically conforms to the real-life application scenario and can be effectively applied to engineering practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the method flow of the present invention. DETAILED DESCRIPTION

[0016] like Figure 1 As shown, a method for selecting a hovering site for a UAV aerial base station based on Stackelberg game includes the following steps:

[0017] Step 1: The aerial base station randomly selects a location to hover and collects the minimum data transmission rate requirements of users in the network and the aerial base station's requests for user sets in three-dimensional space. The maximum total channel gain value;

[0018] Step 2: The air base station uses the Stackelberg game mechanism to collect user Make decisions based on the optimal channel gain information of each user;

[0019] Step 3: The aerial base station forms a three-dimensional channel gain contour for each user based on the user's optimal channel gain information and the location information of each user. If the three-dimensional channel gain contours of all users in have a common intersection, then the aerial base station can be randomly selected in the above intersection and hover in the air, and the algorithm ends; otherwise, the user set Delete the user whose three-dimensional channel gain contour body intersection with other users is the smallest. If there are several such users, delete the user whose three-dimensional channel gain contour body coverage volume is the smallest, and return to step 2.

[0020] The Stackelberg game mechanism described in step 2 is to model the problem of hovering site selection for drone aerial base stations as an economic game model for solution.

[0021] In the game, the aerial base station, as the leader, sells limited channel gain resources, while users, as the buyers, gain benefits by purchasing limited channel gain resources.

[0022] The seller utility function in the game model is defined as the total revenue paid by all users to the air base station for purchasing limited channel gain resources.

[0023] The utility function of the buyer in the game model is defined as the difference between the game benefit of each user's data transmission rate and the game cost of purchasing the channel gain of the air base station, which is

[0024] In step 3, according to the optimal The three-dimensional channel gain contour of the user can be obtained, in which the channel gain from the aerial base station to user m is equal to

[0025] In step 3, if the user set The three-dimensional channel gain contours of all users in have a common intersection, then the aerial base station can be arbitrarily located in the above intersection and hover in the air, and the algorithm ends.

[0026] In step 3, pass the user collection Whether the three-dimensional channel gain contours of all users in the game have a common intersection is used to determine whether multiple rounds of games are needed. If there is no common intersection, multiple rounds of games are started.

[0027] In the initialization phase of the multi-round game, the user set Delete the user whose three-dimensional channel gain contour body intersection with other users is the smallest. If there are several such users, delete the user whose own three-dimensional channel gain contour body volume is the smallest.

[0028] Combination Figure 1 As shown, the design scheme of the present invention is further specifically analyzed and described.

[0029] In the network described in the scheme of the present invention, it is assumed that there are M user terminals defined as user The coordinates of can be accurately located by Beidou satellite positioning system, denoted as L m ={x m ,y m ,z m In the present invention, a drone is set as an aerial base station to serve the M user terminals, and the location information of the drone is L AirBS ={x AirBS ,y AirBS ,z AirBS}.

[0030] In the present invention, considering that the aerial base station is not restricted by position and space and can hover and stay in three-dimensional space, the deployment of the aerial base station has problems such as diversity, complexity and randomness in position, which makes it difficult for the aerial base station to select a hovering site. Therefore, how to reasonably select a hovering site for the aerial base station for multiple users is a key problem that needs to be solved urgently.

[0031] Considering that each user hopes that the aerial base station is closer to himself, so that its path loss is small, so as to obtain a higher data transmission rate. Therefore, in the hovering site selection method of the aerial base station of the unmanned aerial vehicle based on the Stackelberg game provided by the present invention, different users are in a competitive relationship in the issue of purchasing the aerial base station site selection resources. The Stackelberg game is a pure strategy non-cooperative sequential game model in economics. The participants of the game can be divided into leaders and followers according to the priority of the action and the completeness of the information. Followers only have partial information and take the lead in action; while the leader takes action later because he has all the information of the followers. Among them, the leader needs to consider the optimal response of the followers when setting the game strategy, and the followers give their own optimal resource purchase size according to the optimal decision of the leader. In the present invention, since the aerial base station has global information and resources for aerial base station site selection, the aerial base station is used as the leader of the game model to sell its site selection resources, and users who only have partial information act as followers in the game. These followers in the game compete for the resources for aerial base station site selection.

[0032] In the present invention, the purpose of each user (follower) purchasing the resources of the air base station site selection in the game mechanism is to increase the data transmission rate R of its data service. m , that is, for users The gaming payoff is

[0033]

[0034] in: is the average power value allocated by the air base station to the user for its downlink data transmission, σ 2 is the noise at the user receiver, h m is the channel gain from the air base station to user m.

[0035] From the typical path loss formula Where PL(d) is the path loss (in dB) at a distance of d meters from the transmitter, PL(d1) is the known path loss at a reference distance d1, and n is the path loss exponent, which depends on the propagation environment (such as urban, suburban, rural, indoor, etc.).

[0036]

[0037] Also due to d m is the distance from the aerial base station to user m, Then there is

[0038]

[0039] The price that each user (follower) pays for purchasing the resources of the air base station site selection in the game mechanism is the price paid for the improved channel gain, that is, The game cost is

[0040] δ m =βh m

[0041] Among them, β represents the unit channel gain resource price sold by the aerial base station to followers.

[0042] The utility function of a game follower consists of two parts: game gain and game cost, which is

[0043]

[0044] As the number of channel gain resources purchased by followers increases, the benefits of data transmission rate they obtain also increase, but their cost function will also increase. For followers in the game model, their goal is to obtain the highest benefit at the lowest cost in the game behavior, that is, to maximize their own utility function,

[0045]

[0046]

[0047] in, is the minimum data transmission rate requirement value of user m.

[0048] The seller leader in the game relationship, i.e., the air base station, sells its own location information resources to multiple competing users. Therefore, its objective function is defined as the total cost paid by all users to purchase resources, which is

[0049]

[0050] Due to the limited location of aerial base stations, facing a randomly distributed user set The total channel gain in the network cannot be increased indefinitely, so the leader in the Stackelberg game relationship has a constraint of

[0051]

[0052] Among them, h max For the aerial base station to collect users in three-dimensional space The maximum total channel gain value can be obtained from the location information of all users.

[0053] In the game, the airborne base station as the leader aims to gain profits by selling limited channel gain resources. Therefore, the seller's goal in selling is to maximize its own utility function while considering constraints. Therefore, for the leader,

[0054]

[0055]

[0056] The optimization problems at followers and leaders together constitute the Stackelberg game. The final Stackelberg equilibrium can be obtained by the two parties, the leader (airborne base station) and the followers (users), playing games according to certain rules. That is, the optimal unit resource pricing β is obtained by maximizing the utility function representing the interests of the base station and the users with a mutually competitive relationship. * , and then the optimal channel gain information from the air base station to each user can be obtained

[0057] For users The best According to its definition Get the optimal air base station location information for user m and A three-dimensional channel gain contour body can be formed for user m, which is recorded as

[0058] If the user collection The three-dimensional channel gain contours of all users in have a common intersection Right now This means that the aerial base station is The site selection can make All users in the network obtain the optimal channel gain value. Then, the optimal air base station location information is obtained. and The aerial base station performs hovering service at the above address, and the algorithm ends;

[0059] Otherwise when When , it means that the aerial base station cannot be located at any position. To obtain the optimal channel gain value for all users in the to update.

[0060] Calculate the number of intersections between each user's contour body and the contour bodies of other users, which is

[0061]

[0062] Calculate user collection The set of users with the least intersection of the three-dimensional channel gain contours of any user and the other users is

[0063]

[0064] If |ε|=1, it means that there is only one user with the least intersection of three-dimensional channel gain contours, so the user set Delete the user whose three-dimensional channel gain contour intersection with the rest of the users is the least,

[0065]

[0066] If |ε|>1, the three-dimensional channel gain contour volume of the user in ε is calculated as Then delete the user whose three-dimensional channel gain isoheterogeneous volume is the smallest, which is

[0067]

[0068] Updated user collection The Stackelberg game is played again to obtain the optimal channel gain information value from the air base station to the user until all sets The algorithm ends when the three-dimensional channel gain contours of the users have a common intersection.

Claims

1. A method for hovering site selection of UAV aerial base stations based on Stackelberg game, characterized in that: The steps include: Step 1: The aerial base station randomly selects a location to hover and collects the minimum data transmission rate requirements of users in the network and the aerial base station's requests for user sets in three-dimensional space. The maximum total channel gain value; Step 2: The air base station uses the Stackelberg game mechanism to collect user Make decisions based on the optimal channel gain information of each user; Step 3: The aerial base station forms a three-dimensional channel gain contour for each user based on the user's optimal channel gain information and the location information of each user. The three-dimensional channel gain contours of all users in the set have a common intersection, then the aerial base station can be randomly selected in the above intersection and hover in the air; otherwise, the user set Delete the user whose three-dimensional channel gain contour body intersection with other users is the smallest. If there are several such users, delete the user whose three-dimensional channel gain contour body coverage volume is the smallest, and return to step 2.

2. The method for selecting a hovering site for a UAV base station in the air based on Stackelberg game as claimed in claim 1, characterized in that: In step 2, in the game, the aerial base station, as the leader of the two parties in the game, sells limited channel gain resources, and the users, as the buyers in the game, obtain benefits by purchasing limited channel gain resources.

3. The method for selecting a hovering site for a UAV base station in the air based on Stackelberg game as claimed in claim 1, characterized in that: The seller utility function in the game model is defined as the total revenue paid by all users to the air base station for purchasing limited channel gain resources.

4. The method for selecting a hovering site for a UAV base station in the air based on Stackelberg game as claimed in claim 1, characterized in that: The utility function of the buyer in the game model is defined as the difference between the game benefit of each user's data transmission rate and the game cost of purchasing the channel gain of the air base station, which is in: is the average power value allocated by the air base station to the user for its downlink data transmission, σ 2 is the noise at the user receiver, h m is the channel gain from the air base station to user m, and β is the unit resource pricing.

5. The method for selecting a hovering site for a UAV base station in the air based on Stackelberg game as claimed in claim 1, characterized in that: In step 3, according to the optimal The three-dimensional channel gain contour of the user can be obtained, in which the channel gain from the aerial base station to user m is equal to 6. The method for selecting a hovering site for a UAV base station in the air based on Stackelberg game as claimed in claim 1, characterized in that: By user collection Whether multiple rounds of games are needed is determined by whether the three-dimensional channel gain contours of all users in have a common intersection. If there is no common intersection, multiple rounds of games are started.

7. The method for selecting a hovering site for a UAV base station in the air based on Stackelberg game as claimed in claim 1, characterized in that: In the initialization phase of the multi-round game, the user set Delete the user whose three-dimensional channel gain contour body intersection with other users is the smallest. If there are several such users, delete the user whose three-dimensional channel gain contour body volume is the smallest.

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