CN112702703B - Delay-tolerant call service request method for multi-hop air base station cooperation - Google Patents

Abstract

A delay tolerant call service request method of multi-hop air base station cooperation comprises the following steps: step 1: determining initial positions by a plurality of aerial base stations; step 2: initiator G₁To the called party G₂Initiating a call service request; and step 3: the aerial base station processes the call request in the coverage area of a single base station; and 4, step 4: the air base station processes the call request in the coverage range of the cross base station; and 5: the air base station group processes the call request with delay tolerance; step 6: an aerial base station deployment position movement decision; and 7: the air base station activates a call service link; and 8: the air base station is adjusted to the position covering the most ground terminals; and step 9: and (4) concurrent call service handling in the moving process of the air base station. The defects that in the prior art, the aerial base station cannot realize full coverage of all ground terminals, so that the call service cannot be realized among partial ground terminals through aerial base station nodes, and the success rate of the call service among the ground terminals is reduced are effectively overcome.

Description

Delay-tolerant call service request method for multi-hop air base station cooperation

technical field

The present invention relates to the technical field of service request, in particular to a method for requesting a service request of delay tolerant call with multi-hop air base station cooperation.

Background technique

Compared with manned aircraft, UAVs have the advantages of small size, low cost, convenient use, low requirements for the combat environment, and strong battlefield survivability. Since unmanned aircraft is of great significance to future air combat, major military countries in the world are stepping up the development of unmanned aircraft. Base stations (generally using line-of-sight communication frequency bands, such as 300Mhz to 3000Ghz) have obvious advantages in communication coverage compared to ground relay nodes (ground base stations), and at the same time, they have the ability to move quickly, are simple to deploy, and have strong mobility and flexibility. It has been widely used, especially in the field of emergency communication, which has formed a certain scale of application.

In a communication network in which the air base stations are air relay nodes, it may be impossible to achieve full coverage of all ground terminals due to the large distribution area of ground terminals or the limited number of temporary air base stations, so that some ground terminals cannot be implemented through air base station nodes. Call service, reducing the success rate of call service between terrestrial terminals.

SUMMARY OF THE INVENTION

In order to solve the above problems, the present invention provides a multi-hop air base station coordinated delay-tolerant call service request method, which effectively avoids the inability of the air base station to achieve full coverage of all ground terminals in the prior art, resulting in the inability of some ground terminals to pass through the air. The base station node realizes the call service and reduces the defect of the success rate of the call service between the ground terminals.

In order to overcome the deficiencies in the prior art, the present invention provides a solution for a multi-hop air base station coordinated delay-tolerant call service request method, specifically as follows:

A delay-tolerant call service request method for multi-hop air base station cooperation, comprising:

Step 1: Multiple air base stations determine the initial position;

Further, the method for determining the initial position of the multiple air base stations includes: setting the number of air base stations to m and the number of ground terminals to n, where m and n are both positive integers, first of all, these air base stations should determine the initial position of their deployment. Location, when it is impossible to cover all ground terminals in the area, the air base station group should cover the largest number of terminals, so as to build a coverage optimization model, let k _i (i=1, 2, ... n) represent the air base station U The coverage relationship of _j to the ground terminal _Gi , if _ki =j (j=1, 2,...m), it means that the ground terminal _Gi is within the coverage of the air base station U _j and accesses the base station, if k _i =0 means that the ground terminal _Gi is outside the coverage of all air base stations, assuming that the initial position of the air base station U _j is (x _j , y _j ), and the position of the ground terminal Gi is (a _i , b _{i )} Then the optimization model of the air base station group covering the most terminals is shown in formula (1):

s.t.

Where ||(x _j , y _j )-( _ai , b _i )|| represents the Euclidean distance between the two points at the initial position (x _j , y _j ), and the air base station group is obtained by using the nonlinear constraint optimization solution method Best position (x _j , y _j ), j=1, 2, ..., m. The initial position of the air base station U _j should correspond to the optimal position (x _j , y _j ).

Step 2: the initiator G ₁ initiates a call service request to the called party G ₂ ;

Further, the method for the initiating party G ₁ to initiate a call service request to the called party G ₂ includes:

The initiator _G1 sends a call request message, and the message format includes the following elements:

Message type, source terminal ID, destination terminal ID, message sequence number SN, and a time-limited counter _TH that controls message buffering; wherein, the message type is the type of the call request message, and the message sequence number SN distinguishes the call request service of different times, and the source terminal The ID and destination terminal ID are the calling party and the called party number of the call service respectively. The time-limited counter _TH that controls the message cache is set according to the delay tolerance of the calling party's call request; the initiator sends the message at the same time , and also start a local timer, when the timing time T _S of the local timer is exceeded, it is considered that this service is terminated, and T _S is slightly larger than T _H ;

The initiator considers that the service request fails when the local timer expires or when the service termination message sent by the air base station is received.

Step 3: the air base station processes call requests within the coverage of a single base station;

Further, the method for the air base station to process a call request within the coverage of a single base station includes:

It is assumed that after receiving the call request message sent by the initiator G ₁ , the air base station U ₁ identifies the called party ID from the call request message, and the message is forwarded to the called party G ₂ . When the called party is received immediately After the call response message returned by G2, it indicates that _both the calling party _G1 and the called party _G2 are within the coverage _of the air base station U1, and the airborne base station U1 then _forwards the call response message _of the called party G2 to The calling party G ₁ , the calling party G ₁ sends a call confirmation message to the air base station U ₁ , and the air base station completes the call service link G ₁ -U ₁ connecting the calling party G ₁ , the air base station and the called party G ₂ -G ₂ build.

Step 4: the air base station processes the call request within the coverage of the cross base station;

Further, the method for the air base station to process the call request within the coverage of the cross base station includes:

After receiving the call request message sent by the calling party G ₁ , the air base station U ₁ identifies the called party ID from the message, and forwards the message to the called party G ₂ , without immediately receiving the called party G ₂ When the call response message is returned, it indicates that the called party G ₂ is not within the coverage of the air base station U ₁ ; if the air base station U ₁ has other air base stations connected to it, the air base station U ₁ is in all the air base stations communicated with it. The call request message is forwarded within the coverage of the air base station. If the called party G ₂ is in the connected air base station group, it will respond in real time, that is, connect the calling party G ₁ , the air base station U ₁ , the air base station U ₂ and the called party G 1 . _The call service link _{G1 -} U1 _- U2 _- G2 of the calling party G2 is established.

Step 5: The air base station group processes the delay-tolerant call request;

Further, the air base station group processing delay-tolerant call requests includes:

After the air base station U1 receives the call request message sent by the calling party _G1 , it returns to execute steps ₃ and 4 in sequence, and if the call service link cannot be established immediately in response to the call request, it executes a delay-tolerant call request to establish a call service link. business link:

Step 5-1: If the calling party G ₁ is within the coverage of the air base station U ₁ , the air base station U ₁ inquires other air base stations via the Beidou short message and the ad hoc network link to learn that the called party G ₂ is in the air base station U ₂ , but the self-organized network link between the air base station U ₁ and the air base station U ₂ is disconnected. After the call request message sent by the calling party G ₁ reaches the air base station, it cannot be immediately forwarded to the called party G ₂ , the calling party _G1 cannot get the call response immediately, then the calling party U1 caches the call request message _;

Step 5-2: If the calling party G ₁ is within the coverage of the air base station U ₁ , the air base station U ₁ inquires other base stations via the Beidou short message and the ad hoc network link to learn that the called party G ₂ is not covered by the air base station group Within the range, after the call request message sent by the calling party _G1 reaches the air base station, it cannot be immediately forwarded to the called party G2, and the calling party _G1 cannot immediately get _a call response, then the air base station U1 caches the call request message;

Step 5-3: If the calling party _G1 is not within the coverage of the air base station, the call request message of the calling party G1 arrives at the air base station U _a in the form of Beidou short message, and the air base station U _a then passes through the Beidou short message. The form of the message and the ad hoc network link query other base stations to learn that the called party G ₂ is within the coverage of the air base station U ₂ , then the air base station U _a caches the call request message;

Step 5-4: If the calling party G ₁ is not within the coverage of the air base station, the call request message of the calling party G ₁ arrives at the air base station U _a in the form of a Beidou short message, and the air base station U _a then passes through the Beidou short message. The form of short message and the ad hoc network link query other base stations to learn that the called party G ₂ is not within the coverage of the air base station group, then the air base station U _a buffers the call request message.

Step 6: Decision on the movement of the deployment position of the air base station;

Further, the method for deploying the position movement decision of the air base station includes:

Step 6-1: For step _5-1 , the air base station U1 inquires the position of the corresponding ground terminal from the location information base according to the source terminal ID and destination terminal ID in the call request message, and records the calling party _G1 and the called party. The horizontal position coordinates of the party G ₂ are (a ₁ , b ₁ ) and (a ₂ , b ₂ ) respectively, and the air base station U ₁ can know the number of air base stations in the communication area. The specific processing flow is as follows:

Step 6-1-1: If m=2, and ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||>r+2R, the air base station aborts this service request; if ||( a ₁ , b ₁ )-(a ₂ , b ₂ )||≤r+2R, then the air base station executes the position movement strategy;

Set the two air base stations U ₁ and air base station U ₂ to move straight from the positions (x ₁ , y ₁ ) and (x ₂ , y ₂ ) to the horizontal position points (x ₁ ′, y ₁ ′) and (x ₂ ) respectively ′, y ₂ ′), and according to formula (2):

min{max{||(x ₁ , y ₁ )-(x ₁ ′, y ₁ ′)||, ||(x ₂ , y ₂ )-(x ₂ ′, y ₂ ′)||}} ( 2)

s.t.

则空中基站中止本次业务请求；若

则空中基站将调整水平位置部署，沿直线移动至(x₁′，y₁′)和(x₂′，y₂′)；Combining the optimization algorithm based on nonlinear constraints can solve (x ₁ ', y ₁ ') and (x ₂ ', y ₂ '), let d=min{max{||(x ₁ , y ₁ )-(x ₁ ′, y ₁ ′)||, ||(x ₂ , y ₂ )-(x ₂ ′, y ₂ ′)||}}, if

Then the air base station aborts this service request; if

Then the air base station will adjust the horizontal position deployment and move along a straight line to (x ₁ ', y ₁ ') and (x ₂ ', y ₂ ');

Step 6-1-2: If m>2, and ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||≤r+2R, then cover the calling party G ₁ and the called party G respectively ₂ , the air base station U ₁ and the air base station U ₂ , perform the operation of step 6-1-1;

并不中止本次业务请求，继续执行后续操作；若||(a₁，b₁)-(a₂，b₂)||＞2r+2R，则空中基站中止本次业务请求；若||(a₁，b₁)-(a₂，b₂)||≤r+2R且

或r+2R＜||(a₁，b₁)-(a₂，b₂)||≤2r+2R，则空中基站U₁从除空中基站U₁和空中基站U₂之外的基站中选择一个空闲基站，记为空中基站U₃，三个空中基站执行移动策略；of which if

Do not suspend this service request, and continue to perform subsequent operations; if ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||>2r+2R, the air base station suspends this service request; if || (a ₁ , b ₁ )-(a ₂ , b ₂ )||≤r+2R and

Or r+2R<||(a ₁ , b ₁ )-(a ₂ , b ₂ )||≤2r+2R, then the air base station U ₁ is selected from the base stations other than the air base station U ₁ and the air base station U ₂ Select an idle base station, denoted as air base station U ₃ , and three air base stations execute the mobility strategy;

Set up three air base stations, namely air base station U ₁ , air base station U ₂ and air base station U ₃ , which are moved linearly by positions (x ₁ , y ₁ ), (x ₂ , y ₂ ) and (x ₃ , y ₃ ), respectively to the horizontal position points (x ₁ ′, y ₁ ′), (x ₂ ′, y ₂ ′) and (x ₃ ′, y ₃ ′), and according to formula (3):

min{max{||(x ₁ , y ₁ )-(x ₁ ′, y ₁ ′)||, ||(x ₂ , y ₂ )-(x ₂ ′, y ₂ ′)||, || (x ₃ , y ₃ )-(x ₃ ′, y ₃ ′)||}} (3)

s.t.

则空中基站中止本次业务请求；若

则空中基站将调整水平位置部署，沿直线移动至(x₁′，y₁′)、(x₂′，y₂′)和(x₃′，y₃′)；Combined with the optimization algorithm based on nonlinear constraints, (x ₁ ', y ₁ '), (x ₂ ', y ₂ ') and (x ₃ ', y ₃ ') can be solved, let d=min{max{||( x ₁ , y ₁ )-(x ₁ ′, y ₁ ′)||, ||(x ₂ , y ₂ )-(x ₂ ′, y ₂ ′)||, ||(x ₃ , y ₃ ) -(x ₃ ′, y ₃ ′)||}}, if

Then the air base station aborts this service request; if

Then the air base station will adjust the horizontal position deployment and move along a straight line to (x ₁ ', y ₁ '), (x ₂ ', y ₂ ') and (x ₃ ', y ₃ ');

Step 6-2: For step 5-2, the air base station U ₁ inquires the position of the corresponding ground terminal from the location information base according to the source ID and destination ID in the call request message, and records the calling party G ₁ and the called party. The horizontal position coordinates of square G ₂ are (a ₁ , b ₁ ) and (a ₂ , b ₂ ) respectively, and the air base station U ₁ can know the number of air base stations in the communication area. The specific processing flow is as follows:

Step 6-2-1: If ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||≤2R, then the air base station U ₁ executes the position movement strategy, and sets the air base station U ₁ from the horizontal position (x ₁ , y ₁ ) moves straight to the horizontal position point (x ₁ ′, y ₁ ′), and according to formula (4):

min||(x ₁ , y ₁ )-(x ₁ ′, y ₁ ′)|| (4)

s.t.

则空中基站将调整水平位置部署，沿直线移动至(x₁′，y₁′)；Combined with the optimization algorithm based on nonlinear constraints, (x ₁ ′, y ₁ ′) can be solved, let d=||(x ₁ , y ₁ )-(x ₁ ′, y ₁ ′)||, if

Then the air base station will adjust the horizontal position deployment and move along a straight line to (x ₁ ′, y ₁ ′);

Step 6-2-2: If m=2, in addition to the air base station U ₁ , another air base station is used as U ₂ , and then refer to step 6-1-1 to execute;

Step 6-2-3: If m>2, the air base station U ₁ schedules and selects the nearest and idle air base station from the called party G ₂ as the air base station U ₂ through the ad hoc network link or in the form of Beidou short messages, and then connects to the air base station U 2 . Next, refer to step 6-1-2 to execute;

Step 6-3: For step 5-3, the air base station U _a queries the location of the corresponding ground terminal from the location information base according to the source ID and destination ID in the call request message, and records the calling party G ₁ and the called party The horizontal position coordinates of G ₂ are (a ₁ , b ₁ ) and (a ₂ , b ₂ ) respectively, and the air base station U _a can know the number of air base stations in the communication area. The processing flow is as follows:

Step 6-3-1: firstly executed by the air base station U ₂ covering the called party G ₂ with reference to step 6-2-1;

Step 6-3-2: If m=2, in addition to the air base station U ₂ , another air base station is used as U ₁ , and then refer to step 6-1-1 for execution;

Step 6-3-3: If m>2, the air base station U _a schedules the air base station through the self-organized network link or in the form of Beidou short message, and the selection principle is the nearest and idle air base station from the calling party G ₁ as U ₁ , or take the air base station U _a itself as the air base station U ₁ according to this principle, and then refer to step 6-1-2 for execution;

Step 6-4: For step 5-4, the air base station U _a queries the location of the corresponding ground terminal from the location information base according to the source terminal ID and destination terminal ID in the call request message, and records the calling party G ₁ and the called party The horizontal position coordinates of G ₂ are (a ₁ , b ₁ ) and (a ₂ , b ₂ ) respectively, and the air base station U _a can know the number of air base stations in the communication area. The processing flow is as follows:

Step _6-4-1 : _The air base station U _a schedules and selects the air base station through the ad hoc network link or in the form of Beidou short messages. The air base station, or select U _a itself according to this principle, refer to step 6-2-1 for execution;

Step 6-4-2: If m=2, the air base station closest to the calling party G ₁ is used as the air base station U ₁ , and the air base station closest to the called party G ₂ is used as the air base station U ₂ , and then refer to step 6- 1-1 execution;

Step 6-4-3: If m > 2, the air base station U _a schedules and selects the air base station through the ad hoc network link or in the form of Beidou short messages. The principle is the distance between the calling party G ₁ and the called party G ₂ . and the two nearest and idle air base stations in turn are used as air base station U ₁ and air base station U ₂ , wherein the air base station closest to the calling party G ₁ is used as the air base station U ₁ , and the air base station closest to the called party G ₂ is used as the air base station U 1 . The base station U ₂ , or the air base station U _a itself is regarded as the air base station U ₁ or the air base station U ₂ according to this principle, and then refer to step 6-1-2 for execution.

Step 7: the air base station activates the call service link;

Further, the method for activating the call service link by the air base station includes: after the air base station group moves to the estimated position, forwarding the call request message of the calling party G ₁ to the called party G ₂ , and receiving the call request message from the called party G ₂ . After receiving the call response message from the calling party G 1 , it will be forwarded to the calling party G ₁ . After receiving the call confirmation message of the calling party G ₁ , the service link will be activated; the called party G ₂ cannot be received normally. Both the call response message and the call confirmation message of the calling party _G1 will terminate this service request.

Step 8: The air base station is adjusted to the position covering the most ground terminals;

Further, the method for adjusting the air base station to a position covering the most ground terminals includes:

After the call service between the calling party G ₁ and the called party G ₂ is ended, the air base station group participating in the movement, according to the location distribution of the current ground terminals and the positions of other air base stations, will not be able to cover the air base stations within the radius of other air base stations. The ground terminal performs local optimization coverage, that is, covers the maximum number of ground terminals, and moves to the estimated position in a straight line, wherein the solution model is performed with reference to step 1.

Step 9: concurrent call service handling during the movement of the air base station;

Further, the method for handling concurrent call services during the movement of the air base station includes:

The concurrent call service processing of the air base station in the parked state is performed according to the normal process of the existing air base station.

The charging method is as follows:

Step 9-1: Priority to ensure the real-time call request service: If an instant response is obtained when the call request message is forwarded, indicating that both parties to the new call service are within the coverage of the base station, the priority is to ensure that the real-time call request service is normally performed, that is, the direction of movement. Unchanged, but when the signal of both parties or one party of the newly added real-time request is about to be lower than the receiving threshold, stop moving and maintain the current position until the end of the service, and the time spent is included in the call request from the calling party G ₁ to the called party G ₂ If the delay causes a timeout, the service request between the calling party G ₁ and the called party G ₂ should be terminated directly, and then go to step 7 for execution;

Step 9-2: If other call service requests are concurrently added, and it is difficult to realize the new request call immediately, the call should be included in the subsequent service queue of the air base station, buffered, and the buffering timing is started. After processing the calling party _G1 to the called party Call requests between G and ₂ , and then process the subsequent delay-tolerant call requests in a first-in, first-out queue, and those that cause timeouts should be cleared from the queue or terminated.

The beneficial effects of the present invention are:

Aiming at how to realize the call service between the uncovered ground terminals and meet the emergency communication requirements between some ground terminals when the network communication coverage of multiple air base stations is insufficient, the present invention combines the air base stations to move quickly and flexibly change the network topology It innovates the premise requirements of traditional call services for link connectivity and the application characteristics of "one call is connected", and proposes a delay-tolerant call service request method for multi-base station cooperation, which can provide ground service when the network coverage is poor The terminal successfully establishes the call service to the greatest extent and most efficiently, and can be used as an effective supplement to the normal call service process in practical applications to meet the needs of emergency communication.

Description of drawings

FIG. 1 is a schematic diagram of the construction coverage optimization model of the present invention.

FIG. 2 is a schematic diagram of the elements in the message format of the present invention.

FIG. 3 is a schematic diagram of the air base station U instantly establishing the call service link G ₁ -UG ₂ according to the present invention.

FIG. 4 is a schematic diagram of establishing a call service link G ₁ -U ₁ -U ₂ -G ₂ via the air base station U1 and the air base station U2 according to the present invention.

FIG. 5 is a schematic diagram of the movement of a base station in space and time when m=2 according to the present invention.

FIG. 6 is a schematic diagram of the movement of a base station in space and time m>2 according to the present invention.

FIG. 7 is a schematic diagram of the movement of the air base station U1 _of the present invention.

FIG. 8 is a flow chart of a method for requesting a delay-tolerant call service for multi-hop air base station cooperation according to the present invention.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and embodiments.

In the present invention, there should be:

1. The air base station node should include a call service control message buffer unit. The format of the sent call control message should include: message type, source terminal ID, destination terminal ID, message sequence number SN, time-limited counter _TH for the control message buffer of the control message, and the message type includes call request message, call response message and Type of call confirmation message. The initial value of _TH is determined by the call service initiator according to the maximum tolerated delay, in seconds. The determination of the maximum tolerable delay is based on the user's expectation on the connection time of the communication service, which is usually set by the user according to personal needs. For example, the maximum delay tolerance tolerated by the user is 50S, which means that the user expects to be connected within 50 seconds, and if it exceeds 50S, the service will be abandoned.

2. Both the air base station and the ground terminal integrate Beidou positioning and short message functions. The air base station can learn the location information of other air base stations and the location information of all ground terminals. Assuming that there are n ground terminals, their positions are (a _i , b _i ), i=1,2,...,n. where n is the number of ground terminals, i is the number of the ground terminals, (a _i , b _i ) is the ground precise coordinates of the ground terminals, a _i is the longitude coordinates of the ground precise coordinates of the ground terminals, and b _i is the ground precise coordinates of the ground terminals latitude coordinates.

3. The air base station rises to a certain height according to the geographical terrain to achieve line-of-sight coverage for most areas. The reference radius for the horizontal coverage of the ground terminal is R, and the average moving speed is v. In order to provide a certain redundancy, it is recommended to set the horizontal The coverage reference radius is set to a conservative R value.

4. The air base station integrates the self-organized network link, the maximum communication radius is r, and supports multiple air base stations to form an interconnected relay network. The call service link is relayed by the ground terminal through one or more air base stations to reach another ground terminal.

5. According to the time delay requirement of call service transmission, the information carrying the call of the sending terminal reaches the receiving terminal of the opposite party through at most 4 hops (ie, 3 air base station relays).

6. Different air base stations use different frequencies, and the networking between different base stations can avoid wireless interference.

7. The ground terminal is handed over between different base stations. According to the reception threshold criterion, that is, the signal strength of the original base station is lower than that of the adjacent base station, and the handover will not occur. Only when the signal strength of the original base station is lower than the reception threshold (exceeds the original base station coverage), only adjacent base stations that meet the requirements will be selected for access.

8. Judging whether the terminal is within the coverage of a certain air base station is realized according to the request and confirmation of the message, which is practical and accurate, and should be used as far as possible when there are implementation conditions; and coverage optimization and mobile decision-making, to determine whether the deployment location is The coverage of the ground terminal is judged according to the line-of-sight transmission distance, which is theoretically accurate, and there may be certain errors in engineering.

9. Over-the-air base station mobility decision estimation in the process of processing delay-tolerant call service requests is a relatively simple nonlinear constrained optimization problem, and the processing time is negligible.

As shown in Fig. 1-Fig. 8, the method for requesting a delay-tolerant call service for multi-hop air base station cooperation includes:

Step 1: Multiple air base stations determine the initial position;

The method for determining the initial position of the multiple air base stations includes: setting the number of air base stations to m and the number of ground terminals to n, where m and n are both positive integers, first of all, these air base stations should determine the initial position of their deployment, and then When it is impossible to cover all ground terminals in the area, the air base station group should cover the largest number of terminals, so as to build a coverage optimization model, let k _i (i=1, 2, ... n) represent the air base station U _j to the ground The coverage relationship of the terminal Gi, _j is the number of the air base station, i is the number of the ground terminal, if k _i =j (j=1, 2, ... m), it means that the ground terminal _Gi is in the air base station U _j If _ki = 0, it means that the ground terminal G _i is outside the coverage of all air base stations. Assuming that the initial position of the air base station U _j is (x _j , y _j ), the ground terminal G i The position of _i is (a _i , b _i ), (x _j , y _j ) is the precise ground coordinates of the air base station U _j , where j is the number of the air base station, and x _j is the longitude of the ground precise coordinates of the air base station U _j Coordinate, y _j is the latitude coordinate of the ground precise coordinate of the air base station U _j .

Then, as shown in Figure 1, the optimization model of the base station group covering the most terminals in the air is shown in formula (1):

s.t.

where ||(x _j , y _j )-(a _i , b _i )|| represents the initial position (x _j , y _j ) of the air base station U _j and the position (a _i , b _i ) of the plane terminal G _i The Euclidean distance between them can be obtained by adopting the nonlinear constraint optimization solution method to obtain the optimal position (x _j , y _j ) of the base station group in the air, j=1, 2,...,m. The initial position of the air base station U _j should correspond to the optimal position (x _j , y _j ). The nonlinear constrained optimization solution method can be a heuristic algorithm. The air base station group consists of all air base stations. (a _i , b _i ) are the ground precise coordinates of the ground terminal G _i , i is the ground terminal number, a _i is the longitude coordinate of the ground precise coordinates of the ground terminal G _i , and b _i is the ground precise coordinates of the ground terminal G _i Latitude coordinates. (x _j , y _j ) are the ground precise coordinates of the air base station U _j , where j is the number of the air base station, x _j is the longitude coordinate of the ground precise coordinates of the air base station U _j , and y _j is the ground precise coordinate of the air base station U _j The latitude coordinates of the coordinates.

Step ₂ : The initiator G1 initiates a call service request to the called party G2 _; the initiator _G1 and the called party G2 are _both ground terminals.

The method for initiating a call service request by the initiator G ₁ to the called party G ₂ includes:

The initiator _G1 sends a call request message, and the message format includes the following elements:

Message type, source terminal ID, destination terminal ID, message sequence number SN, and a time-limited counter _TH that controls message buffering; wherein, the message type is the type of the call request message, and the message sequence number SN distinguishes the call request service of different times, and the source terminal The ID and destination terminal ID are the calling party number and the called party number of the call service respectively, and the time-limited counter _TH of the control message buffer is set according to the delay tolerance degree of the calling party's call request; A local timer will also be started, and when the timing time T _S of the local timer is exceeded, it is considered that this service is terminated, and considering the transmission and processing delay, T _S is slightly larger than T _H ;

The initiator considers that the service request fails when the local timer expires or when the service termination message sent by the air base station is received.

Step 3: the air base station processes call requests within the coverage of a single base station;

The method for processing a call request within the coverage of a single base station by the air base station includes:

It is assumed that after receiving the call request message sent by the initiator G ₁ , the air base station U ₁ identifies the called party ID from the call request message, and the message is forwarded to the called party G ₂ . When the called party is received immediately After the call response message returned by G2, it indicates that _both the calling party _G1 and the called party _G2 are within the coverage _of the air base station U1, and the airborne base station U1 then _forwards the call response message _of the called party G2 to The calling party G ₁ , the calling party G ₁ sends a call confirmation message to the air base station U ₁ , and the air base station completes the call service chain connecting the calling party G ₁ , the air base station and the called party G ₂ as shown in FIG. 3 Road G ₁ -U ₁ -G ₂ is established.

Step 4: the air base station processes the call request within the coverage of the cross base station;

The method for the air base station to process the call request within the coverage of the cross base station includes:

After receiving the call request message sent by the calling party G ₁ , the air base station U ₁ identifies the called party ID from the message, and forwards the message to the called party G ₂ , without immediately receiving the called party G ₂ When the call response message is returned, it indicates that the called party G ₂ is not within the coverage of the air base station U ₁ ; if the air base station U ₁ has other air base stations connected to it, the air base station U ₁ is in all the air base stations communicated with it. The call request message is forwarded within the coverage of the air base station. If the called party G ₂ is in the connected air base station group, it will respond in real time. As shown in Figure 4, the called party G ₂ is within the coverage of the air base station U ₂ . , and the air base station U1 and the air base station _U2 are connected via the ad hoc network link, then the called party _G2 sends _a call response message to the air base station _U2 , and forwards it to the air base station _U1 , and finally forwards it to the calling party Party G ₁ , the calling party G ₁ replies with a call confirmation message, that is, the call service link G ₁ -U ₁ -U ₂ connecting the calling party G ₁ , the air base station U ₁ , the air base station U ₂ and the called party G ₂ -G ₂ build.

Step 5: The air base station group processes the delay-tolerant call request;

The air base station group handles delay-tolerant call requests, including:

After the air base station U1 receives the call request message sent by the calling party _G1 , it returns to execute steps ₃ and 4 in sequence, and if the call service link cannot be established immediately in response to the call request, it executes a delay-tolerant call request to establish a call service link. business link:

Step 5-1: If the calling party G ₁ is within the coverage of the air base station U ₁ , the air base station U ₁ inquires other air base stations via the Beidou short message and the ad hoc network link to learn that the called party G ₂ is in the air base station U ₂ , but the self-organized network link between the air base station U ₁ and the air base station U ₂ is disconnected. After the call request message sent by the calling party G ₁ reaches the air base station, it cannot be immediately forwarded to the called party G ₂ , the calling party _G1 cannot get the call response immediately, then the calling party U1 caches the call request message _;

Step 5-2: If the calling party G ₁ is within the coverage of the air base station U ₁ , the air base station U ₁ inquires other base stations via the Beidou short message and the ad hoc network link to learn that the called party G ₂ is not covered by the air base station group Within the range, after the call request message sent by the calling party _G1 reaches the air base station, it cannot be immediately forwarded to the called party G2, and the calling party _G1 cannot immediately get _a call response, then the air base station U1 caches the call request message;

Step 5-3: If the calling party _G1 is not within the coverage of the air base station, the call request message of the calling party G1 arrives at the air base station U _a in the form of Beidou short message, and the air base station U _a then passes through the Beidou short message. The form of the message and the ad hoc network link query other base stations to learn that the called party G ₂ is within the coverage of the air base station U ₂ , and the air base station U _a may also be the air base station U ₂ , then the air base station U _a caches the call request message ; In the form of Beidou short message, the record selection of the most recent access to the air base station can be used, or a certain base station can be preset as the base station to be accessed by Beidou short message when it is not within the coverage area.

Step 5-4: If the calling party G ₁ is not within the coverage of the air base station, the call request message of the calling party G ₁ arrives at the air base station U _a in the form of a Beidou short message, and the air base station U _a then passes through the Beidou short message. The form of short message and the ad hoc network link query other base stations to learn that the called party G ₂ is not within the coverage of the air base station group, then the air base station U _a buffers the call request message.

Step 6: Decision on the movement of the deployment position of the air base station;

The method for deploying the position movement decision of the air base station includes:

Step 6-1: For step _5-1 , the air base station U1 inquires the position of the corresponding ground terminal from the location information base according to the source terminal ID and destination terminal ID in the call request message, and records the calling party _G1 and the called party. The horizontal position coordinates of the party G ₂ are (a ₁ , b ₁ ) and (a ₂ , b ₂ ) respectively, and the air base station U ₁ can know the number of air base stations in the communication area. The specific processing flow is as follows: the called party G ₂ is The destination terminal, the calling party G ₁ is the source terminal. (a ₁ , b ₁ ) and (a ₂ , b ₂ ) are the horizontal position coordinates of the calling party G ₁ and the called party G ₂ of the ground terminal, respectively. a ₁ and a ₂ are corresponding longitude coordinates, and b ₁ and b ₂ are corresponding latitude coordinates.

Step 6-1-1: If m=2, and ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||>r+2R, the air base station aborts this service request; if ||( a ₁ , b ₁ )-(a ₂ , b ₂ )||≤r+2R, then the air base station executes the position movement strategy;

Among them, r is the effective communication distance between air base stations, and R is the conservative value of the horizontal coverage of the air base station to the ground terminal, that is, the minimum coverage is taken to ensure the effectiveness of the air base station coverage and a certain degree of redundancy. value.

Set the two air base stations U ₁ and air base station U ₂ to move straight from the positions (x ₁ , y ₁ ) and (x ₂ , y ₂ ) to the horizontal position points (x ₁ ′, y ₁ ′) and (x ₂ ) respectively ', y ₂ '), (x ₁ , y ₁ ) and (x ₂ , y ₂ ) are the initial position coordinates of the air base station U1 and the air base station U2 respectively, x ₁ , x ₂ are the corresponding longitude coordinates, y ₁ , y ₂ is the corresponding latitude coordinate. (x ₁ ', y ₁ ') and (x ₂ ', y ₂ ') are the position coordinates of the air base station U1 and the air base station U2 after the first move as required, and x ₁ ' and x ₂ ' are the corresponding longitudes coordinates, y ₁ ′, y ₂ ′ are the corresponding latitude coordinates. And according to formula (2):

min{max{||(x ₁ , y ₁ )-(x ₁ ′, y ₁ ′)||, ||(x ₂ , y ₂ )-(x ₂ ′, y ₂ ′)||}} ( 2)

s.t.

则空中基站中止本次业务请求；若

d为空中基站U1和空中基站U2Combining the optimization algorithm based on nonlinear constraints can solve (x ₁ ', y ₁ ') and (x ₂ ', y ₂ '), let d=min{max{||(x ₁ , y ₁ )-(x ₁ ′, y ₁ ′)||, ||(x ₂ , y ₂ )-(x ₂ ′, y ₂ ′)||}}, if

Then the air base station aborts this service request; if

d is the air base station U1 and the air base station U2

The maximum value of the two values of the straight-line distance (shortest movement) between the initial position and the position after the first movement, ν is the average movement speed of the drone, and _TH is the time-limited counter value of the control message buffer. The meaning of the formula is that the maximum value of the moving process time of the air base station cannot exceed the value of the time-limited counter (user delay tolerance), and it is meaningless to move beyond the value.

As shown in Figure 5, the air base station will adjust the horizontal position deployment, and move along a straight line to (x ₁ ', y ₁ ') and (x ₂ ', y ₂ ');

Step 6-1-2: If m>2, and ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||≤r+2R, then cover the calling party G ₁ and the called party G respectively ₂ , the air base station U ₁ and the air base station U ₂ , perform the operation of step 6-1-1;

并不中止本次业务请求，继续执行后续操作；若||(a₁，b₁)-(a₂，b₂)||＞2r+2R，则空中基站中止本次业务请求；若||(a₁，b₁)-(a₂，b₂)||≤r+2R且

或r+2R＜||(a₁，b₁)-(a₂，b₂)||≤2r+2R，则空中基站U₁从除空中基站U₁和空中基站U₂之外的基站中选择一个空闲基站，记为空中基站U₃，三个空中基站执行移动策略；所述选择一个可以是到空中基站U₁和空中基站U₂距离和最小且空闲的空中基站，若无空闲的空闲基站就加入排队来延迟等候有空闲基站再进行选择。of which if

Do not suspend this service request, and continue to perform subsequent operations; if ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||>2r+2R, the air base station suspends this service request; if || (a ₁ , b ₁ )-(a ₂ , b ₂ )||≤r+2R and

Or r+2R<||(a ₁ , b ₁ )-(a ₂ , b ₂ )||≤2r+2R, then the air base station U ₁ is selected from the base stations other than the air base station U ₁ and the air base station U ₂ Select an idle base station, denoted as air base station U ₃ , and three air base stations implement the mobility strategy; the selected one can be the air base station with the smallest and idle distance to the air base station U ₁ and the air base station U ₂ , if there is no idle idle The base station joins the queue to delay and wait for an idle base station before making a selection.

Set up three air base stations, namely air base station U1, air base station U2 and air base station U3, and move linearly from positions (x ₁ , y ₁ ), (x ₂ , y ₂ ) and (x ₃ , y ₃ ) to the horizontal position respectively points (x ₁ ′, y ₁ ′), (x ₂ ′, y ₂ ′) and (x ₃ ′, y ₃ ′), and according to formula (3):

min{max{||(x ₁ , y ₁ )-(x ₁ ′, y ₁ ′)||, ||(x ₂ , y ₂ )-(x ₂ ′, y ₂ ′)||, || (x ₃ , y ₃ )-(x ₃ ′, y ₃ ′)||}} (3)

s.t.

则空中基站中止本次业务请求；若

如图6所示，则空中基站将调整水平位置部署，沿直线移动至(x₁′，y₁′)、(x₂′，y₂′)和(x₃′，y₃′)；m＝2时，说明有2个空中基站，分别为空中基站U₁，另一个为空中基站U₂，若||(a₁，b₁)-(a₂，b₂)||＞r+2R，则空中基站中止本次业务请求；若||(a₁，b₁)-(a₂，b₂)||≤r+2R，则空中基站执行位置移动策略，使得地面终端G₁和G₂分别在空中基站U₁和U₂的覆盖范围内，且空中基站U₁和U₂符合通信联通要求，则根据移动位置距离进行条件判定，是否符合位置移动调整要求。Combined with the optimization algorithm based on nonlinear constraints, (x ₁ ', y ₁ '), (x ₂ ', y ₂ ') and (x ₃ ', y ₃ ') can be solved, let d=min{max{||( x ₁ , y ₁ )-(x ₁ ′, y ₁ ′)||, ||(x ₂ , y ₂ )-(x ₂ ′, y ₂ ′)||, ||(x ₃ , y ₃ ) -(x ₃ ′, y ₃ ′)||}}, if

Then the air base station aborts this service request; if

As shown in Figure 6, the air base station will adjust the horizontal position deployment, and move along a straight line to (x ₁ ', y ₁ '), (x ₂ ', y ₂ ') and (x ₃ ', y ₃ '); m When = 2, it means that there are two air base stations, one is the air base station U ₁ , and the other is the air base station U ₂ , if ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||>r+2R , the air base station aborts this service request; if ||( _{a 1} , b ₁ )-(a ₂ , b ₂ )|| ₂ are within the coverage of air base stations U ₁ and U ₂ respectively, and air base stations U ₁ and U ₂ meet the requirements of communication and connectivity, then conditionally determine whether they meet the position movement adjustment requirements according to the moving position distance.

Step 6-2: For step 5-2, the air base station U ₁ inquires the position of the corresponding ground terminal from the location information base according to the source ID and destination ID in the call request message, and records the calling party G ₁ and the called party. The horizontal position coordinates of square G ₂ are (a ₁ , b ₁ ) and (a ₂ , b ₂ ) respectively, and the air base station U ₁ can know the number of air base stations in the communication area. The specific processing flow is as follows:

Step 6-2-1: If ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||≤2R, then the air base station U ₁ executes the position movement strategy, and sets the air base station U ₁ from the horizontal position (x ₁ , y ₁ ) moves straight to the horizontal position point (x ₁ ′, y ₁ ′), and according to formula (4):

min||(x ₁ , y ₁ )-(x ₁ ′, y ₁ ′)|| (4)

s.t.

如图7所示，则空中基站将调整水平位置部署，沿直线移动至(x₁′，y₁′)；Combined with the optimization algorithm based on nonlinear constraints, (x ₁ ′, y ₁ ′) can be solved, let d=||(x ₁ , y ₁ )-(x ₁ ′, y ₁ ′)||, if

As shown in Figure 7, the air base station will adjust the horizontal position and move to (x ₁ ', y ₁ ') along a straight line;

Step 6-2-2: If m=2, in addition to the air base station U ₁ , another air base station is used as U ₂ , and then refer to step 6-1-1 to execute; when m=2, it means that there are two air base stations, respectively is an air base station U ₁ , and the other is an air base station U ₂ , if ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||>r+2R, the air base station aborts this service request; if | |(a ₁ , b ₁ )-(a ₂ , b ₂ )||≤r+2R, then the air base station executes the position movement strategy, so that the ground terminals G ₁ and G ₂ are covered by the air base stations U ₁ and U ₂ respectively Within the range, and the air base stations U ₁ and U ₂ meet the requirements of communication and connectivity, the conditional determination is made according to the distance of the moving position to determine whether it meets the position movement.

或r+2R＜||(a₁，b₁)-(a₂，b₂)||≤2r+2R，则空中基站U₁从除空中基站U₁和空中基站U₂之外的基站中选择一个空闲基站，记为空中基站U₃，所述选择的空中基站U₃可以是到空中基站U₁和空中基站U₂距离和最小且空闲的空中基站，则空中基站执行位置移动策略，使得地面终端G₁和G₂分别在空中基站U₁和U₂的覆盖范围内，空基站U₃则作为基站U₁和U₂联通的中间转接基站，则根据移动位置距离进行条件判定，是否符合位置移动调整要求。Step 6-2-3: If m>2, the air base station U ₁ schedules and selects the nearest and idle air base station from the called party G ₂ as the air base station U ₂ through the ad hoc network link or in the form of Beidou short messages, and then connects to the air base station U 2 . Next, refer to step 6-1-2 for execution; when m > 2, it means that there are at least 3 air base stations, namely air base station U ₁ , and another air base station U ₁ schedules and selects through the ad hoc network link or in the form of Beidou short messages The air base station that is closest to the called party terminal G ₂ and is idle is used as the air base station U ₂ . If it is found through the positioning calculation that the distance between the terminals of G ₁ and G ₂ satisfies ||(a ₁ , b ₁ )-(a ₂ , b ₂ ) ||≤r+2R, follow step 6-1-1; if ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||>2r+2R, the air base station suspends this service request , because the distance is too large, 3 air base stations cannot meet the information communication requirements; if ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||≤r+2R and

Or r+2R<||(a ₁ , b ₁ )-(a ₂ , b ₂ )||≤2r+2R, then the air base station U ₁ is selected from the base stations other than the air base station U ₁ and the air base station U ₂ Select an idle base station, denoted as air base station U ₃ , the selected air base station U ₃ can be the air base station with the smallest and idle distance to the air base station U ₁ and the air base station U ₂ , then the air base station executes the position movement strategy, so that The ground terminals G ₁ and G ₂ are respectively within the coverage of the air base stations U ₁ and U ₂ , and the air base station U ₃ is used as an intermediate transfer base station for the communication between the base stations U ₁ and U ₂ , and the condition is determined according to the distance of the moving position. Meet the requirements of position movement adjustment.

Step 6-3: For step 5-3, the air base station U _a queries the location of the corresponding ground terminal from the location information base according to the source ID and destination ID in the call request message, and records the calling party G ₁ and the called party The horizontal position coordinates of G ₂ are (a ₁ , b ₁ ) and (a ₂ , b ₂ ) respectively, and the air base station U _a can know the number of air base stations in the communication area. The processing flow is as follows:

则执行位置移动策略。Step 6-3-1: firstly executed by the air base station U ₂ covering the called party G ₂ with reference to step 6-2-1; the air base station U ₂ learns the calling party terminal G ₁ and the called party G ₂ through the Beidou positioning function The coordinate position of , it is known through calculation that if ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||≤2R, it means that the air base station U ₂ can cover 2 ground terminals at the same time, then the optimal calculation Position movement strategy, if the shortest distance d moved by the base station in the air can satisfy d=||(x ₁ , y ₁ )-(x ₁ ′, y ₁ ′)||,

Then the position movement strategy is executed.

Step 6-3-2: If m=2, in addition to the air base station U ₂ , another air base station is used as U ₁ , and then refer to step 6-1-1 for execution;

或r+2R＜||(a₁，b₁)-(a₂，b₂)||≤2r+2R，则空中基站U₂从除空中基站U₁和空中基站U₂之外的基站中选择一个空闲基站，记为空中基站U₃，所述选择的空中基站U₃可以是到空中基站U₁和空中基站U₂距离和最小且空闲的空中基站，则空中基站执行位置移动策略，使得地面终端G₁和G₂分别在空中基站U₁和U₂的覆盖范围内，空基站U₃则作为基站U₁和U₂联通的中间转接基站，则根据移动位置距离进行条件判定，是否符合位置移动调整要求。Step 6-3-3: If m>2, the air base station U _a schedules and selects the nearest and idle air base station from the calling party G ₁ through the ad hoc network link or in the form of Beidou short messages as U ₁ , or According to this principle, the air base station U _a itself is regarded as the air base station U ₁ , and then refer to step 6-1-2 for execution; when m>2, it means that there are at least 3 air base stations, which are the air base station U ₂ and the air base station U 2 respectively. _a Select the nearest and idle air base station from the calling and called party terminal _{G 1} as the air base station U ₁ through the ad hoc network link or in the form _of Beidou short message scheduling. _a is U ₁ . If the distance between the terminal positions of G ₁ and G ₂ satisfies ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||≤r+2R, then follow step 6-1 -1 is executed; if ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||>2r+2R, the air base station aborts this service request, because the distance is too large, 3 air base stations cannot satisfy the information Unicom requirements; if ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||≤r+2R and two air base stations move

Or r+2R<||(a ₁ , b ₁ )-(a ₂ , b ₂ )||≤2r+2R, then the air base station U ₂ is selected from the base stations other than the air base station U ₁ and the air base station U ₂ Select an idle base station, denoted as air base station U ₃ , the selected air base station U ₃ can be the air base station with the smallest and idle distance to the air base station U ₁ and the air base station U ₂ , then the air base station executes the position movement strategy, so that The ground terminals G ₁ and G ₂ are respectively within the coverage of the air base stations U ₁ and U ₂ , and the air base station U ₃ is used as an intermediate transfer base station for the communication between the base stations U ₁ and U ₂ , and the condition is determined according to the distance of the moving position. Meet the requirements of position movement adjustment.

Step 6-4: For step 5-4, the air base station U _a queries the location of the corresponding ground terminal from the location information base according to the source ID and destination ID in the call request message, and records the calling party G ₁ and the called party The horizontal position coordinates of G ₂ are (a ₁ , b ₁ ) and (a ₂ , b ₂ ) respectively, and the air base station U _a can know the number of air base stations in the communication area. The processing flow is as follows:

则执行位置移动策略。这里U_a即可能是那个符合要求的空中基站U。Step _6-4-1 : _The air base station U _a schedules and selects the air base station through the ad hoc network link or in the form of Beidou short messages. The air base station, or select U _a itself according to this principle, refer to the reference step 6-2-1 for execution; the air base station U _a schedules and selects the air base station U through the ad hoc network link or in the form of Beidou short messages, and the principle is to The sum of the distance between the calling party G ₁ and the called party G ₂ is the closest and idle, and the air base station U obtains the coordinate positions of the calling party terminal G ₁ and the called party G ₂ through the Beidou positioning function. ₁ , b ₁ )-(a ₂ , b ₂ )||≤2R, it means that the air base station U can cover 2 ground terminals at the same time, then calculate the optimal position movement strategy, if the air base station moves the shortest distance d can satisfy d=||(x ₁ , y ₁ )-(x ₁ ′, y ₁ ′)||,

Then the position movement strategy is executed. Here U _a may be the air base station U that meets the requirements.

Step 6-4-2: If m=2, the air base station closest to the calling party G ₁ is used as the air base station U ₁ , and the air base station closest to the called party G ₂ is used as the air base station U ₂ , and then refer to step 6- 1-1 is executed; when m=2, it means that there are 2 air base stations. Through Beidou positioning, the air base station close to the calling party G ₁ can be used as the air base station U ₁ , and the air base station closest to the called party G ₂ can be used as the air base station U 1 . Base station U ₂ , the distance between terminal G ₁ and terminal G ₂ ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||>r+2R, the air base station suspends this service request; if ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||≤r+2R, then the air base station executes the position movement strategy, so that the ground terminals G ₁ and G ₂ are respectively within the coverage of the air base stations U ₁ and U ₂ , And if the air base stations U ₁ and U ₂ meet the requirements of communication and connectivity, the conditional determination is made according to the distance of the moving positions, whether they meet the requirements of position movement adjustment.

或r+2R＜||(a₁，b₁)-(a₂，b₂)||≤2r+2R，则从空中基站U₁和U₂之外的基站中选择一个空闲基站，记为空中基站U₃，所述选择的空中基站U₃可以是到空中基站U₁和空中基站U₂距离和最小且空闲的空中基站，则空中基站执行位置移动策略，使得地面终端G₁和G₂分别在空中基站U₁和U₂的覆盖范围内，空基站U₃则作为基站U₁和U₂联通的中间转接基站，则根据移动位置距离进行条件判定，是否符合位置移动调整要求。Step 6-4-3: If m>2, the air base station U _a schedules the selection principle through the ad hoc network link or in the form of Beidou short messages: the sum of the distances to the calling party G ₁ and the called party G ₂ is the closest in sequence And the two idle air base stations are used as air base station U ₁ and air base station U ₂ , wherein the air base station closest to the calling party G ₁ is used as air base station U ₁ , and the air base station closest to the called party G ₂ is used as air base station U ₂ , or according to this principle, the air base station U _a itself is regarded as the air base station U ₁ or the air base station U ₂ , and then refer to step 6-1-2 for execution. When m>2, it means that there are at least 3 air base stations, namely the air base station U ₁ closest to the calling party terminal G ₁ , and the air base station U ₂ closest to the called party terminal G ₂ (here U _a itself may be U ₁ or U ₂ ), if it is found through the positioning calculation that the distance between the terminal positions of G ₁ and G ₂ satisfies ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||≤r+2R, then follow step 6- 1-1 execution; if ||(a ₁ , b ₁ )-(a ₂ , b ₂ )|| > 2r+2R, the air base station aborts this service request, and 3 air base stations cannot satisfy it because the distance is too large Information communication requirements; if ||(a ₁ , b ₁ )-(a ₂ , b ₂ )||≤r+2R and only two base stations move, make

Or r+2R<||(a ₁ , b ₁ )-(a ₂ , b ₂ )||≤2r+2R, then select an idle base station from the base stations other than the air base stations U ₁ and U ₂ , denoted as The air base station U ₃ , the selected air base station U ₃ may be the air base station with the smallest and idle distance to the air base station U ₁ and the air base station U ₂ , then the air base station executes the position movement strategy, so that the ground terminals G ₁ and G ₂ Within the coverage _of the air base stations U1 and _U2 respectively, the air base station _U3 is used as _an intermediate transfer base station for the communication between the base stations U1 and _U2 , and the condition is determined according to the distance of the moving position, whether it meets the position movement adjustment requirements.

Step 7: the air base station activates the call service link;

The method for activating a call service link by the air base station includes: in various situations, after the air base station group moves to the estimated position, forwarding the call request message of the calling party G ₁ to the called party G ₂ , and receiving the call request message from the called party After the call response message of G2, it will be forwarded to the calling party _G1 , and after receiving the call confirmation message of the calling party _G1 , the service link (may be a single base station relay, two base stations ₎ will be activated. relay or three-base station relay network); when the call response message of the called party G ₂ and the call confirmation message of the calling party G ₁ cannot be received normally, the service request will be terminated.

Step 8: The air base station is adjusted to the position covering the most ground terminals;

The method for adjusting the air base station to a position covering the most ground terminals includes:

After the call service between the calling party G ₁ and the called party G ₂ is ended, the air base station group participating in the movement, according to the location distribution of the current ground terminals and the positions of other air base stations, will not be able to cover the air base stations within the radius of other air base stations. The ground terminal performs local optimization coverage, that is, covers the maximum number of ground terminals, and moves to the estimated position in a straight line, wherein the solution model is performed with reference to step 1. Referring to step 1, that is, after the air base station completes the current service, the air base station group should cover the largest number of terminals, calculate the strategy according to the model formula (1), and adjust the position.

Step 9: concurrent call service handling during the movement of the air base station;

The method for handling concurrent call services during the movement of the air base station includes:

The concurrent call service processing of the air base station in the parked state is performed according to the normal process of the existing air base station. During the moving process, if other call service requests are concurrent, the supplementary processing methods are as follows:

Step 9-1: Guarantee the real-time request call service preferentially: Since the delay-tolerant call service request method is a supplement to the normal service, the normal real-time request call service should be given priority. If an instant response is obtained when the call request message is forwarded, it means that both parties to the newly added call service are within the coverage of the base station, and priority is given to ensuring that the service of the real-time request call is carried out normally, that is, the moving direction remains unchanged, but the two parties to the newly added real-time request call or When the signal of one party is about to be lower than the receiving threshold, it should stop moving and maintain the current position until the end of the service. The time spent will be included in the call request delay from the calling party G1 to the called party G2. If a timeout occurs, the calling party G1 should be terminated directly. To the service request between the called party G2, and then go to step 7 for execution; the meaning of the reception threshold: in the information communication, the minimum value of the signal transmission and reception between the two parties is set to ensure the communication quality. If the value is lower than this value, the normal communication. For example, if the receiving threshold is 50dB, if the signal strength is higher than 50dB, it means normal communication is possible, and if it is lower than 50dB, it means that the signal is not good and cannot communicate normally.

Step 9-2: If other call service requests are concurrently added, and it is difficult to realize the new request call immediately, it should be included in the subsequent service queue of the air base station, cached and start the cache timing, and the calling party G1 to the called party G2 are processed. The call request between the two, and then the subsequent delay-tolerant call request is processed according to the first-in-first-out queue, and the service request that causes the timeout should be cleared from the queue or terminated.

The present invention has been described above by means of the embodiments, and those skilled in the art should understand that the present disclosure is not limited to the above-described embodiments, and various changes can be made without departing from the scope of the present invention. change and replace.

Claims (3)

1. A method for requesting a delay tolerant call service in multi-hop cooperation with an air base station is characterized by comprising the following steps:

step 1: determining initial positions by a plurality of aerial base stations;

step 2: initiator G₁To the called party G₂Initiating a call service request;

and step 3: the aerial base station processes the call request in the coverage area of a single base station;

and 4, step 4: the air base station processes the call request in the coverage range of the cross base station;

and 5: the air base station group processes the call request with delay tolerance;

step 6: an aerial base station deployment position movement decision;

and 7: the air base station activates a call service link;

and 8: the air base station is adjusted to the position covering the most ground terminals;

and step 9: handling concurrent call service in the moving process of the air base station;

the initiator G₁To the called party G₂The method for initiating the call service request comprises the following steps:

the initiator G₁Sending a call request message, wherein the message format comprises the following elements:

message type, source terminal ID, destination terminal ID, message sequence number SN and time-limited counter T for controlling message buffer_H(ii) a The message type is the type of the call request message, the message serial number SN distinguishes the call request service of different times, the source terminal ID and the target terminal ID are the calling party number and the called party number of the call service of the time respectively, and the time-limited counter T for controlling the message cache_HSetting a delay tolerance degree according to a calling request of a calling party; when the initiator sends a message, the initiator also starts a local timer, and the timing time T of the local timer is exceeded_SConsidering the service termination, T_SGreater than T_H；

The initiator considers that the service request fails when the local timer is overtime or receives a service termination message sent by the air base station;

the method for processing the call request in the coverage area of the single base station by the air base station comprises the following steps:

setting an airborne base station U₁Receiving an initiator G₁After the call request message is sent, the called party ID is identified from the call request message, which is forwarded to the called party G₂Receiving the called party G when in time₂After the call response message is replied to, this indicates the calling party G₁And the called party G₂Are all in the air base station U₁Within the coverage area of the base station U in the air₁The called party G is called again₂Forwards the call response message to the calling party G₁Calling party G₁To aerial base station U₁Sending a call confirmation message, the air base station completes the connection of the calling party G₁Aerial base station and called party G₂Call service link G of₁-U₁-G₂Establishing;

the method for processing the call request in the coverage area of the cross base station by the air base station comprises the following steps:

the aerial base station U₁Receive masterCaller G₁After the call request message is sent, the called party ID is identified from the message, and the message is forwarded to the called party G₂Not receiving called party G immediately₂When a call response message is returned, this indicates the called party G₂Off-air base station U₁Within the coverage of (c); if the air base station U₁With other air base stations, air base stations U, in communication therewith₁Forwarding the call request message in the coverage area of all air base stations connected with it, if called party G₂Within the connected air base station group, real-time response is made, i.e. calling party G is connected₁Aerial base station U₁Aerial base station U₂And the called party G₂Call service link G of₁-U₁-U₂-G₂Establishing;

the group of air base stations processing delay tolerant call requests, comprising:

the aerial base station U₁Receiving a calling party G₁After the call request message is sent, returning to the sequence to execute the step 3 and the step 4, if the call service link can not be immediately established in response to the call request, executing the delay tolerant call request to establish the service link:

step 5-1: if the calling party G₁In the air base station U₁Within the coverage area of the base station U in the air₁The called party G is obtained by inquiring other air base stations through Beidou short messages and ad hoc network links₂In the air base station U₂But an airborne base station U₁And an aerial base station U₂The ad hoc network link is disconnected, calling party G₁After the transmitted call request message reaches the air base station, the message can not be forwarded to the called party G immediately₂Calling party G₁The calling party U can not obtain the call response immediately₁Caching the call request message;

step 5-2: if the calling party G₁In the air base station U₁Within the coverage area of the base station U in the air₁The called party G is obtained by inquiring other base stations through Beidou short messages and Ad hoc network links₂Out of coverage of the air base station group, calling party G₁Sending a callAfter the request message arrives at the air base station, the request message can not be forwarded to the called party G immediately₂Calling party G₁If the call response can not be obtained immediately, the air base station U₁Caching the call request message;

step 5-3: if the calling party G₁Out of coverage of the airborne base station, calling party G₁The call request message reaches an aerial base station U in the form of Beidou short message_aAerial base station U_aThen, the called party G is obtained by inquiring other base stations through the Beidou short message and the Ad hoc network link₂In the air base station U₂Within the coverage area of (2), then the aerial base station U_aCaching the call request message;

step 5-4: if the calling party G₁Out of coverage of the airborne base station, calling party G₁The call request message reaches an aerial base station U in the form of Beidou short message_aAerial base station U_aThen, other base stations are inquired by the Beidou short message form and the Ad hoc network link to acquire the called party G₂If the mobile station is not in the coverage area of the air base station group, the air base station U_aCaching the call request message;

the method for the aerial base station deployment position movement decision comprises the following steps:

step 6-1: for step 5-1, the airborne base station U₁According to the source terminal ID and the destination terminal ID in the call request message, the position of the corresponding ground terminal is inquired from the position information base, and the calling party G is recorded₁And the called party G₂Has horizontal position coordinates of (a)₁，b₁) And (a)₂，b₂) Simultaneous air base station U₁The number of base stations in the air in a communication area can be obtained, and the specific processing flow is as follows:

step 6-1-1: if m is 2, and | | (a)₁，b₁)-(a₂，b₂) If the | is more than R +2R, the air base station stops the service request; if (a)₁，b₁)-(a₂，b₂) If the | is less than or equal to R +2R, the air base station executes a position moving strategy; m is the number of aerial base stations, R is the reference radius of the aerial base stations to the horizontal coverage range of the ground terminal, v is the unmanned planeThe average moving speed, r is the maximum communication distance between the base stations in the air;

setting two air base stations U₁And an aerial base station U₂Respectively by position (x)₁，y₁) And (x)₂，y₂) Straight line to horizontal position point (x'₁，y′₁) And (x'₂，y′₂) And according to formula (2):

min{max{||(x₁，y₁)-(x′₁，y′₁)||，||(x₂，y₂)-(x′₂，y′₂)||}} (2)

s.t.

solving for (x 'in combination with a non-linear constraint based optimization algorithm'₁，y′₁) And (x'₂，y′₂) Let d be min { max { | (x)₁，y₁)-(x′₁，y′₁)||，||(x₂，y₂)-(x′₂，y′₂) If | }, if

The air base station stops the service request; if it is

The aerial base station will adjust the horizontal position deployment, moving in a straight line to (x'₁，y′₁) And (x'₂，y′₂)；

Step 6-1-2: if m >2, and | | (a)₁，b₁)-(a₂，b₂) R +2R is less than or equal to | |, then covering the calling party G₁And the called party G₂Aerial base station U₁And an aerial base station U₂Executing the operation of step 6-1-1;

and wherein if

Continuing to execute subsequent operation without stopping the service request; if (a)₁，b₁)-(a₂，b₂) If the | | is more than 2R +2R, the air base station stops the service request; if (a)₁，b₁)-(a₂，b₂) R +2R is less than or equal to | |

Or R +2R < | | (a)₁，b₁)-(a₂，b₂) If | | | is less than or equal to 2R +2R, then the aerial base station U₁From removing aerial base station U₁And an aerial base station U₂Selecting one idle base station from other base stations and recording as an air base station U₃Three airborne base stations implement a mobility strategy;

three air base stations, namely an air base station U1, an air base station U2 and an air base station U3 are respectively set to be composed of positions (x)₁，y₁)、(x₂，y₂) And (x)₃，y₃) Straight line to horizontal position point (x'₁，y′₁)、(x′₂，y′₂) And (x'₃，y′₃) And according to formula (3):

min{max{||(x₁，y₁)-(x′₁，y₁′)||，||(x₂，y₂)-(x′₂，y′₂)||，||(x₃，y₃)-(x′₃，y′₃)||}} (3)

s.t.

solving for (x 'in combination with a non-linear constraint based optimization algorithm'₁，y′₁)、(x′₂，y′₂) And (x'₃，y′₃) Let d be min { max { | (x)₁，y₁)-(x′₁，y′₁)||，||(x₂，y₂)-(x′₂，y′₂)||，||(x₃，y₃)-(x′₃，y′₃) If | }, if

The air base station stops the service request; if it is

The aerial base station will adjust the horizontal position deployment, moving in a straight line to (x'₁，y′₁)、(x′₂，y′₂) And (x'₃，y′₃)；

Step 6-2: for step 5-2, the airborne base station U₁According to the source end ID and the destination end ID in the call request message, the position of the corresponding ground terminal is inquired from the position information base, and the calling party G is recorded₁And the called party G₂The horizontal position coordinates are respectively (a)₁，b₁) And (a)₂，b₂) Simultaneous air base station U₁The number of base stations in the air in a communication area can be obtained, and the specific processing flow is as follows:

step 6-2-1: if (a)₁，b₁)-(a₂，b₂) When | | < 2R, then the aerial base station U₁Executing the position moving strategy and setting the air base station U₁From the horizontal position (x)₁，y₁) Straight line to horizontal position point (x'₁，y′₁) And according to equation (4):

min||(x₁，y₁)-(x′₁，y′₁)|| (4)

s.t.

solving for (x 'in combination with a non-linear constraint based optimization algorithm'₁，y₁'), let d | | (x)₁，y₁)-(x′₁，y′₁) If

The aerial base station will adjust the horizontal position deployment, moving in a straight line to (x'₁，y′₁)；

Step 6-2-2: if m is 2, except for the airborne base station U₁Another aerial base station as U₂Next, it is performed with reference to step 6-1-1;

step 6-2-3: if m is more than 2, the aerial base station U₁Distance called party G is scheduled and selected through an ad hoc network link or in a Beidou short message mode₂Nearest and idle aerial base station as aerial base station U₂Next, it is performed with reference to step 6-1-2;

step 6-3: for step 5-3, the airborne base station U_aAccording to the source end ID and the destination end ID in the call request message, the position of the corresponding ground terminal is inquired from the position information base, and the calling party G is recorded₁And called G₂Has horizontal position coordinates of (a)₁，b₁) And (a)₂，b₂) Simultaneous air base station U_aThe number of base stations in the air in a communication area can be obtained, and the processing flow is as follows:

step 6-3-1: first of all by covering the called party G₂Aerial base station U₂Is performed with reference to step 6-2-1;

step 6-3-2: if m is 2, except for the airborne base station U₂Another aerial base station is used as U₁Next, it is performed with reference to step 6-1-1;

step 6-3-3: if m is more than 2, the aerial base station U_aScheduling selection principle as a distance calling party G through an ad hoc network link or in a form of Beidou short message₁Nearest and idle aerial base station as U₁Or according to the principle, the aerial base station U_aItself as an aerial base station U₁Next, it is performed with reference to step 6-1-2;

step 6-4: for step 5-4, the airborne base station U_aAccording to the source end ID and the destination end ID in the call request message, the position of the corresponding ground terminal is inquired from the position information base, and the calling party G is recorded₁And called G₂Has horizontal position coordinates of (a)₁，b₁) And (a)₂，b₂) Simultaneous air base station U_aThe number of base stations in the air in a communication area can be obtained, and the processing flow is as follows:

step 6-4-1: aerial base station U_aThe air base station is scheduled and selected through an ad hoc network link or in a Beidou short message mode, and the principle is that the calling party G is reached₁And the called party G₂The idle aerial base station with the shortest distance sum or U is selected according to the principle_aSelf, the execution is carried out with reference to the step 6-2-1;

step 6-4-2: if m is 2, G is distance from the calling party₁The near aerial base station is used as an aerial base station U₁From the called party G₂The nearest aerial base station is taken as an aerial base station U₂Next, with reference to step 6-1-1;

step 6-4-3: if m is more than 2, the aerial base station U_aThe air base station is scheduled and selected through an ad hoc network link or in a Beidou short message mode, and the principle is that the calling party G is reached₁And the called party G₂Two idle aerial base stations with the distance sum being sequentially nearest are used as aerial base stations U₁And an aerial base station U₂Wherein is distant from the calling party G₁The nearest aerial base station is taken as an aerial base station U₁From the called party G₂The nearest aerial base station is taken as an aerial base station U₂Or according to the principle, the aerial base station U_aItself as an aerial base station U₁Or aerial base station U₂And is next performed with reference to step 6-1-2.

2. The method for requesting a delay tolerant call service in multi-hop cooperation with an air base station according to claim 1, wherein the method for adjusting the air base station to the position covering the most ground terminals comprises:

end calling party G₁And the called party G₂After the inter-call service, the air base station group participating in the movement carries out local optimal coverage on the ground terminals which are not within the coverage radius of other air base stations according to the position distribution of the current ground terminals and the positions of other air base stations, namely, the ground terminals cover the maximum number of ground terminals and move to the estimated position in a straight line, wherein the calculation is carried outThe solution model is performed with reference to step 1.

3. The method for requesting delay tolerant call traffic in multi-hop cooperative air base station according to claim 1, wherein the method for handling concurrent call traffic during the moving process of the air base station comprises:

the air base station processes the concurrent call service in the parking state and executes the processing according to the normal flow of the existing air base station, and if other call service requests are concurrent in the moving process, the supplementary processing method comprises the following steps:

step 9-1: preferentially ensuring real-time request call service: if an instant response is obtained when the call request message is forwarded, which indicates that both sides of the newly added call service are in the coverage range of the base station, the service of the real-time request call is preferentially ensured to be normally carried out, namely the moving direction is not changed, but when the signals of both sides or one side of the newly added real-time request call are about to be lower than a receiving threshold, the movement is stopped to maintain the current position until the service is ended, and the consumed time is counted into the calling party G₁To the called party G₂The calling party G should be terminated directly by delaying the call request, resulting in a timeout₁To the called party G₂Then, the service request is carried out in step 7;

step 9-2: if other new call service requests are simultaneously sent and it is difficult to realize that the new request call should be brought into the subsequent service queue of the air base station in real time, the buffer memory is carried out and the buffer memory timing is started, and the calling party G is processed₁To the called party G₂In between, the subsequent delay tolerant call requests are processed in a first-in-first-out queue, resulting in the overtime request to be cleared or terminated from the queue.

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