OLSR protocol self-adaption method and system in network topology change environment

Abstract

The invention discloses an OLSR protocol adaptive method and system in a network topology change environment, and the method comprises the steps: firstly, dynamically adjusting the stability of an OLSR protocol link through employing a HELLO message, then dynamically adjusting the sending interval of the HELLO message through employing a node neighbor change rate, and then obtaining a HELLO packet received by a node i in one HELLO message sending interval; according to the method, the function that the sending interval of the HELLO message is automatically adjusted along with the change rate of the node neighbor so as to adapt to the dynamic change of the network topology is realized, and more stable MPR nodes and end-to-end paths can be selected according to the predicted link duration, so that the OLSR protocol has self-adaptive capability to the change of the network topology structure; and the OLSR protocol can achieve the effects of balancing overhead and improving network performance in a high-dynamic network environment, so that not only is the response capability of the node to link perception enhanced, but also the end-to-end path is more stable, and the method is suitable for being widely popularized and used.

Description

Technical Field

[0001] The present invention relates to the technical field of OLSR protocol, and in particular to an OLSR protocol self-adaptation method and system under a network topology change environment. Background Art

[0002] Wireless self-organizing networks have broad application prospects in academic research, commercial market, earthquake relief and military operations. For example, a multi-UAV system organized in a self-organizing manner can more efficiently collaborate to complete complex tasks than a single large UAV system. The efficiency of the routing protocol is crucial to the performance of wireless self-organizing networks. Among them, the OLSR (Optimized Link State Routing) protocol is one of the widely used table-driven active routing protocols. The OLSR protocol is an optimization of the classic link state algorithm, and the concept of multipoint relay is used in the protocol to select a part of the nodes from the one-hop neighbor nodes of this node as MPR nodes (Multipoint Relay), and the control messages in the network are forwarded by the MPR nodes, thereby significantly reducing the control overhead. The OLSR protocol performs link state perception and global routing establishment by broadcasting HELLO messages and TC (Topology Control) messages.

[0003] At present, in the standard OLSR protocol, link perception and neighbor discovery are completed by broadcasting HELLO messages at a fixed period. Since fixed-period broadcasts cannot adapt to the high-speed movement of nodes in the network, the network topology will change dynamically, resulting in outdated topology information and routing failure. However, in scenarios where the topology changes slowly, more frequent broadcasts of control messages will occupy network resources, thereby increasing routing overhead. Most of the existing path selection methods cannot fully consider the movement direction, speed and channel quality between nodes, resulting in short link duration of the elected MPR node, poor channel quality and low path stability, which seriously degrades network performance. Therefore, it is necessary to design an OLSR protocol adaptive method and system under the network topology change environment. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art, and to better and effectively solve the problem that the existing path selection methods mostly fail to fully consider the moving direction, speed and channel quality between nodes, resulting in the short link duration of the selected MPR node, poor channel quality and low path stability. An OLSR protocol self-adaptation method and system under a network topology change environment are provided, which realizes the function of automatically adjusting the sending interval of HELLO messages according to the speed of the node neighbor change rate to adapt to the dynamic change of the network topology, and can select more stable MPR nodes and end-to-end paths according to the predicted link duration, so that the OLSR protocol has the ability to adapt to the changes in the network topology structure, and the OLSR protocol can achieve the effect of balancing the overhead and improving the network performance in a highly dynamic network environment, which not only enhances the node's responsiveness to link perception, but also makes the end-to-end path more stable.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: An OLSR protocol self-adaptation method under a network topology change environment comprises the following steps: Step A, using HELLO message to dynamically adjust the OLSR protocol link stability; Step B, dynamically adjust the sending interval of HELLO messages using the node neighbor change rate; Step C, obtaining the HELLO packets received by node i within a HELLO message sending interval, and then using the node geographic location and node speed information in the HELLO packet to calculate the link duration between node i and the adjacent node j; Step D, using the link duration between node i and adjacent node j to adjust the MPR selection and path selection of the OLSR protocol, completing the OLSR protocol adaptive adjustment operation.

[0006] In the aforementioned OLSR protocol self-adaptation method under a network topology change environment, step A uses HELLO messages to dynamically adjust the OLSR protocol link stability, specifically, waiting for the HELLO message timer to time out.

[0007] In the aforementioned OLSR protocol adaptive method under a network topology change environment, step B uses the node neighbor change rate to dynamically adjust the HELLO message sending interval. Specifically, after the HELLO message timer times out, each node compares the last HELLO message with the current HELLO message to calculate and save the neighbor change rate, and then calculates the average change rate of the neighbors in the previous t-1 HELLO messages. The specific steps are as follows: Step B1, when calculating the neighbor change rate, the newly added node and the node leaving the communication range are regarded as the changed neighbors, and then the average neighbor change rate in the current HELLO message is calculated and saved, so as to find the average neighbor change rate in the previous t-1 HELLO messages; Step B2, comparing the neighbor change rate in the current HELLO message with the average neighbor change rate in the previous t-1 HELLO messages and modifying the HELLO message sending interval; Step B3: setting the Htime value and the Vtime value in the HELLO message according to the modified HELLO message sending interval.

[0008] The aforementioned OLSR protocol self-adaptation method under a network topology change environment, step B1 specifically comprises the following steps: Step B11, calculate the neighbor node change rate in the HELLO cycle, as shown in formula (1), (1) Among them, N i Indicates the number of newly added one-hop neighbors, M i represents the number of one-hop neighbors left, K i represents the total number of one-hop neighbors in the i-th HELLO message, represents the neighbor change rate in the i-th HELLO message; Step B12, calculate the average neighbor change rate in the t-1 HELLO messages before the jth HELLO message , as shown in formula (2), (2).

[0009] The aforementioned OLSR protocol self-adaptation method under a network topology change environment, step B2 specifically comprises the following steps: Step B21, if the neighbor change rate of the jth HELLO message Less than the average neighbor change rate in the first t-1 HELLO messages , it means that the change of node neighbors is gradually decreasing and the local topology change is becoming flat, so the sending interval of HELLO messages is increased; Step B22: If the neighbor change rate of the jth HELLO message Greater than the average neighbor change rate in the first t-1 HELLO messages , it means that the node neighbor changes are gradually increasing and the local topology changes are intensifying, reducing the frequency of sending HELLO messages; Step B23, if the neighbor change rate of the jth HELLO message Equal to the average neighbor change rate in the first t-1 HELLO messages , it means that the node neighbors change steadily and the node local topology changes steadily, and the HELLO message sending interval is kept at the initial default value; Step B24, modify the HELLO message sending interval, as shown in formula (3), (3) Among them, Interval represents the sending interval of HELLO message, m0 represents the default sending interval value of HELLO message, m1 represents the sending interval value after reduction, and m2 represents the sending interval value after increase. , and is a positive real number.

[0010] The aforementioned OLSR protocol self-adaptation method under a network topology change environment, step B3 specifically comprises the following steps: Step B31, setting the Htime value in the HELLO message according to the modified HELLO message sending interval, as shown in formula (4), (4); Step B32, setting the Vtime value in the HELLO message according to the modified HELLO message sending interval, as shown in formula (5), (5).

[0011] In the aforementioned OLSR protocol adaptive method under a network topology change environment, step C obtains the HELLO packet received by node i within a HELLO message sending interval, and then uses the node geographic location and node speed information in the HELLO packet to calculate the link duration between node i and the adjacent node j, wherein the specific calculation steps of the link duration between node i and the adjacent node j are as follows: Step C1, calculate the distance that node i and node j move from the current time to the next time t as shown in formula (6) and formula (7), respectively. (6) (7) Among them, d i and d j They represent the distances that nodes i and j move from the current moment to the next moment t, respectively, and v i and v j Represent the speed of node i and node j respectively; Step C2, calculate the coordinates of node i and node j at the next time t as shown in formula (8) and formula (9), respectively. , , (8) , , (9) Among them, x i ,y i 、z i and x j ,y j 、z j Respectively represent the coordinates of node i and node j at the next time t, , and , Respectively represent the angles between the moving directions of nodes i and j, , and They represent the three-dimensional coordinates of node i at the previous moment, , and Respectively represent the three-dimensional coordinates of node j at the previous moment; Step C3, calculate the distance D between node i and node j at the next time t, as shown in formula (10), , , ; , , ; (10) Among them, a, b, and c represent the components of distance D in the x, y, and z directions, respectively. , and They represent the components of the relative velocity between node i and node j in the x, y, and z directions respectively; Step C4, assuming that the distance between node i and node j at the next time t is R, the link duration time LET between node i and adjacent node j is as shown in formula (11): , , ; ; (11) in, , and All indicate set values.

[0012] The aforementioned OLSR protocol self-adaptation method under a network topology change environment, step D, uses the link duration between node i and adjacent node j to adjust the MPR selection and path selection of the OLSR protocol to complete the OLSR protocol self-adaptation adjustment operation, the specific steps are as follows, Step D1, using the link duration between node i and adjacent node j to adjust the MPR selection of the OLSR protocol, the specific steps are as follows: Step D11, normalize the link duration between node i and node j, as shown in formula (12), (12) in, represents the normalized link duration, LET max Indicates the maximum link duration, LET min Indicates the minimum link duration; Step D12, using the normalized link duration The willingness is weighted to complete the adjustment of the MPR selection of the OLSR protocol, as shown in formula (13): (13) in, Indicates the original willingness of the node, represents weighted willingness; Step D2, using the link duration between node i and adjacent node j to adjust the path selection of the OLSR protocol, specifically, using the link duration between node i and node j to weight ETX to complete the path selection of the OLSR protocol, as shown in formula (14), (14) in, represents the weighted ETX, and They represent the forward propagation probability and reverse propagation probability of the link respectively.

[0013] An OLSR protocol self-adaptive system under a network topology change environment comprises a link stability adjustment module, a sending interval adjustment module, a link duration calculation module and an OLSR protocol adjustment module, wherein the link stability adjustment module is used to dynamically adjust the link stability of the OLSR protocol by using a HELLO message; the sending interval adjustment module is used to dynamically adjust the sending interval of the HELLO message by using a node neighbor change rate; the link duration calculation module is used to obtain a HELLO packet received by a node i within a HELLO message sending interval, and then calculate the link duration between the node i and an adjacent node j by using the node geographical location and node speed information in the HELLO packet; the OLSR protocol adjustment module is used to adjust the MPR selection and path selection of the OLSR protocol by using the link duration between the node i and the adjacent node j, thereby completing the OLSR protocol self-adaptive adjustment operation.

[0014] The beneficial effects of the present invention are as follows: an OLSR protocol self-adaptation method and system in a network topology change environment of the present invention firstly utilizes HELLO messages to dynamically adjust the OLSR protocol link stability, then utilizes the node neighbor change rate to dynamically adjust the HELLO message sending interval, then obtains the HELLO packet received by node i within a HELLO message sending interval, and then utilizes the node geographic location and node speed information in the HELLO packet to calculate the link duration between node i and adjacent node j, and then utilizes the link duration between node i and adjacent node j to adjust the MPR selection and path selection of the OLSR protocol to complete the OLSR protocol self-adaptation adjustment operation; effectively realizes that the OLSR protocol self-adaptation method and system have the function of automatically adjusting the HELLO message sending interval with the speed of the node neighbor change rate to adapt to the dynamic change of the network topology, and can select more stable MPR nodes and end-to-end paths according to the predicted link duration, so that the OLSR protocol has the ability to adapt to the change of the network topology structure, and the OLSR protocol can achieve the effect of balancing the overhead and improving the network performance in a highly dynamic network environment, which not only enhances the node's response ability to link perception, but also makes the end-to-end path more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is an overall flow chart of an OLSR protocol self-adaptation method under a network topology change environment of the present invention. DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with the accompanying drawings.

[0017] like Figure 1 As shown, the OLSR protocol self-adaptation method under a network topology change environment of the present invention comprises the following steps: Step A: dynamically adjust the OLSR protocol link stability by using the HELLO message, specifically, waiting for the HELLO message timer to time out.

[0018] Step B, dynamically adjust the sending interval of HELLO messages by using the node neighbor change rate. Specifically, after the HELLO message timer times out, each node compares the last HELLO message with the current HELLO message to calculate and save the neighbor change rate, and then finds the average change rate of neighbors in the previous t-1 HELLO messages. The specific steps are as follows: Step B1, when calculating the neighbor change rate, take the newly added node and the node leaving the communication range as the changed neighbors, then calculate and save the average neighbor change rate in the current HELLO message, so as to find the average neighbor change rate in the previous t-1 HELLO messages. The specific steps are as follows: Among them, the first t-1 HELLO messages are selected to calculate the average neighbor change rate in order to make the sliding average window adapt to the rapid changes in the topology in the mobile ad hoc network scenario. A larger window will make the response mechanism slow, while a smaller window will cause numerical jitter, making it difficult to stabilize the frequency regulation.

[0019] Step B11, calculate the neighbor node change rate in the HELLO cycle, as shown in formula (1), (1) Among them, N i Indicates the number of newly added one-hop neighbors, M i represents the number of one-hop neighbors left, K i represents the total number of one-hop neighbors in the i-th HELLO message, represents the neighbor change rate in the i-th HELLO message; Step B12, calculate the average neighbor change rate in the t-1 HELLO messages before the jth HELLO message , as shown in formula (2), (2).

[0020] Step B2, compare the neighbor change rate in the current HELLO message with the average neighbor change rate in the previous t-1 HELLO messages and modify the HELLO message sending interval. The specific steps are as follows: Among them, comparing the neighbor change rate in the current HELLO message with the average neighbor change rate in the previous t-1 HELLO messages is to convert the change rate into a relative value; if the neighbor change rate in the current HELLO message is greater than the average neighbor change rate in the previous t-1 HELLO messages by a threshold α, the sending interval of the HELLO message is reduced to keep the link information fresh; if the neighbor change rate in the current HELLO message is between α and β compared with the average neighbor change rate in the previous t-1 HELLO messages, the sending interval of the current HELLO message is maintained; if the neighbor change rate in the current HELLO message is less than the threshold β compared with the average neighbor change rate in the previous t-1 HELLO messages, the sending interval of the HELLO message is increased to reduce the network control overhead; Step B21, if the neighbor change rate of the jth HELLO message Less than the average neighbor change rate in the first t-1 HELLO messages , it means that the change of node neighbors is gradually decreasing and the local topology change is becoming flat, so the sending interval of HELLO messages is increased; Step B22: If the neighbor change rate of the jth HELLO message Greater than the average neighbor change rate in the first t-1 HELLO messages , it means that the node neighbor changes are gradually increasing and the local topology changes are intensifying, reducing the frequency of sending HELLO messages; Step B23, if the neighbor change rate of the jth HELLO message Equal to the average neighbor change rate in the first t-1 HELLO messages , it means that the node neighbors change steadily and the node local topology changes steadily, and the HELLO message sending interval is kept at the initial default value; Step B24, modify the HELLO message sending interval, as shown in formula (3), (3) Among them, Interval represents the sending interval of HELLO message, m0 represents the default sending interval value of HELLO message, m1 represents the sending interval value after reduction, and m2 represents the sending interval value after increase. , and is a positive real number.

[0021] Step B3, setting the Htime value and Vtime value in the HELLO message according to the modified HELLO message sending interval, the specific steps are as follows: Among them, Htime and Vtime are set to make the effective time of the HELLO message keep the same as the sending interval of the HELLO message. A shorter HELLO sending interval uses a shorter effective time, which avoids the accumulation of neighbor information in the node's neighbor database and causes incorrect link calculation. A longer HELLO sending interval uses a longer effective time, which allows the node's neighbor information to be kept for a longer time without being lost. Step B31, setting the Htime value in the HELLO message according to the modified HELLO message sending interval, as shown in formula (4), (4); Step B32, setting the Vtime value in the HELLO message according to the modified HELLO message sending interval, as shown in formula (5), (5).

[0022] Step C, obtaining the HELLO packets received by node i within a HELLO message sending interval, and then using the node geographic location and node speed information in the HELLO packet to calculate the link duration between node i and the adjacent node j, wherein the specific calculation steps of the link duration between node i and the adjacent node j are as follows: Step C1, calculate the distance that node i and node j move from the current time to the next time t as shown in formula (6) and formula (7), respectively. (6) (7) Among them, d i and d j They represent the distances that nodes i and j move from the current moment to the next moment t, respectively, and v i and v j Represent the speed of node i and node j respectively; Step C2, calculate the coordinates of node i and node j at the next time t as shown in formula (8) and formula (9), respectively. , , (8) , , (9) Among them, x i ,y i 、z i and x j ,yj 、z j Respectively represent the coordinates of node i and node j at the next time t, , and , Respectively represent the angles between the moving directions of nodes i and j, , and They represent the three-dimensional coordinates of node i at the previous moment, , and Respectively represent the three-dimensional coordinates of node j at the previous moment; Step C3, calculate the distance D between node i and node j at the next time t, as shown in formula (10), , , ; , , ; (10) Among them, a, b, and c represent the components of distance D in the x, y, and z directions, respectively. , and They represent the components of the relative velocity between node i and node j in the x, y, and z directions respectively; Step C4, assuming that the distance between node i and node j at the next time t is R, the link duration time LET between node i and adjacent node j is as shown in formula (11): , , ; ; (11) in, , and All indicate set values.

[0023] Step D, using the link duration between node i and adjacent node j to adjust the MPR selection and path selection of the OLSR protocol, completes the OLSR protocol adaptive adjustment operation, the specific steps are as follows, Step D1, using the link duration between node i and adjacent node j to adjust the MPR selection of the OLSR protocol, the specific steps are as follows: Step D11, normalize the link duration between node i and node j, as shown in formula (12), (12) in, represents the normalized link duration, LET max Indicates the maximum link duration, LET min Indicates the minimum link duration; Step D12, using the normalized link duration The willingness is weighted to complete the adjustment of the MPR selection of the OLSR protocol, as shown in formula (13): (13) in, Indicates the original willingness of the node, represents weighted willingness; Step D2, using the link duration between node i and adjacent node j to adjust the path selection of the OLSR protocol, specifically, using the link duration between node i and node j to weight ETX to complete the path selection of the OLSR protocol, as shown in formula (14), (14) in, represents the weighted ETX, and They represent the forward propagation probability and reverse propagation probability of the link respectively.

[0024] An OLSR protocol self-adaptive system under a network topology change environment comprises a link stability adjustment module, a sending interval adjustment module, a link duration calculation module and an OLSR protocol adjustment module, wherein the link stability adjustment module is used to dynamically adjust the link stability of the OLSR protocol by using a HELLO message; the sending interval adjustment module is used to dynamically adjust the sending interval of the HELLO message by using a node neighbor change rate; the link duration calculation module is used to obtain a HELLO packet received by a node i within a HELLO message sending interval, and then calculate the link duration between the node i and an adjacent node j by using the node geographical location and node speed information in the HELLO packet; the OLSR protocol adjustment module is used to adjust the MPR selection and path selection of the OLSR protocol by using the link duration between the node i and the adjacent node j, thereby completing the OLSR protocol self-adaptive adjustment operation.

[0025] In summary, the present invention provides an OLSR protocol self-adaptation method and system in a network topology change environment. First, HELLO messages are used to dynamically adjust the OLSR protocol link stability. Then, the node neighbor change rate is used to dynamically adjust the HELLO message sending interval. Subsequently, the HELLO packet received by node i within a HELLO message sending interval is obtained. Then, the node geographic location and node speed information in the HELLO packet are used to calculate the link duration between node i and the adjacent node j. Then, the link duration between node i and the adjacent node j is used to adjust the MPR selection and path selection of the OLSR protocol to complete the OLSR protocol self-adaptation adjustment operation. The OLSR protocol self-adaptation method and system are effectively implemented to have the function of automatically adjusting the HELLO message sending interval with the speed of the node neighbor change rate to adapt to the dynamic changes of the network topology. According to the predicted link duration, more stable MPR nodes and end-to-end paths can be selected to make the OLSR protocol self-adaptive to the changes in the network topology structure. In addition, the OLSR protocol can achieve the effect of balancing the overhead and improving the network performance in a highly dynamic network environment, which not only enhances the node's responsiveness to link perception, but also makes the end-to-end path more stable.

[0026] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An OLSR protocol self-adaptation method under a network topology change environment, characterized by: The following steps are included: Step A, using HELLO message to dynamically adjust the OLSR protocol link stability; Step B, dynamically adjust the sending interval of HELLO messages using the node neighbor change rate; Step C, obtaining the HELLO packets received by node i within a HELLO message sending interval, and then using the node geographic location and node speed information in the HELLO packet to calculate the link duration between node i and the adjacent node j; Step D, using the link duration between node i and adjacent node j to adjust the MPR selection and path selection of the OLSR protocol, completing the OLSR protocol adaptive adjustment operation.

2. The OLSR protocol self-adaptation method under a network topology change environment according to claim 1, characterized in that: Step A: dynamically adjust the OLSR protocol link stability by using the HELLO message, specifically, waiting for the HELLO message timer to time out.

3. The OLSR protocol self-adaptation method under a network topology change environment according to claim 2, characterized in that: Step B, dynamically adjust the sending interval of HELLO messages by using the node neighbor change rate. Specifically, after the HELLO message timer times out, each node compares the last HELLO message with the current HELLO message to calculate and save the neighbor change rate, and then finds the average change rate of neighbors in the previous t-1 HELLO messages. The specific steps are as follows: Step B1, when calculating the neighbor change rate, the newly added node and the node leaving the communication range are regarded as the changed neighbors, and then the average neighbor change rate in the current HELLO message is calculated and saved, so as to find the average neighbor change rate in the previous t-1 HELLO messages; Step B2, comparing the neighbor change rate in the current HELLO message with the average neighbor change rate in the previous t-1 HELLO messages and modifying the HELLO message sending interval; Step B3: setting the Htime value and the Vtime value in the HELLO message according to the modified HELLO message sending interval.

4. The OLSR protocol self-adaptation method under a network topology change environment according to claim 3, characterized in that: Step B1 The specific steps are as follows: Step B11, calculate the neighbor node change rate in the HELLO cycle, as shown in formula (1), （1） Among them, N i Indicates the number of newly added one-hop neighbors, M i represents the number of one-hop neighbors left, K i represents the total number of one-hop neighbors in the i-th HELLO message, represents the neighbor change rate in the i-th HELLO message; Step B12, calculate the average neighbor change rate in the t-1 HELLO messages before the jth HELLO message , as shown in formula (2), （2）。 5. The OLSR protocol self-adaptation method under a network topology change environment according to claim 4, characterized in that: The specific steps of step B2 are as follows: Step B21, if the neighbor change rate of the jth HELLO message Less than the average neighbor change rate in the first t-1 HELLO messages , it means that the change of node neighbors is gradually decreasing and the local topology change is becoming flat, so the sending interval of HELLO messages is increased; Step B22: If the neighbor change rate of the jth HELLO message Greater than the average neighbor change rate in the first t-1 HELLO messages , it means that the node neighbor changes are gradually increasing and the local topology changes are intensifying, reducing the frequency of sending HELLO messages; Step B23, if the neighbor change rate of the jth HELLO message Equal to the average neighbor change rate in the first t-1 HELLO messages , it means that the node neighbors change steadily and the node local topology changes steadily, and the HELLO message sending interval is kept at the initial default value; Step B24, modify the HELLO message sending interval, as shown in formula (3), （3） Among them, Interval represents the sending interval of HELLO message, m0 represents the default sending interval value of HELLO message, m1 represents the sending interval value after reduction, and m2 represents the sending interval value after increase. , and is a positive real number.

6. The OLSR protocol self-adaptation method under a network topology change environment according to claim 5, characterized in that: Step B3: The specific steps are as follows: Step B31, setting the Htime value in the HELLO message according to the modified HELLO message sending interval, as shown in formula (4), （4）； Step B32, setting the Vtime value in the HELLO message according to the modified HELLO message sending interval, as shown in formula (5), （5）。 7. The OLSR protocol self-adaptation method under a network topology change environment according to claim 6, characterized in that: Step C, obtaining the HELLO packets received by node i within a HELLO message sending interval, and then using the node geographic location and node speed information in the HELLO packet to calculate the link duration between node i and the adjacent node j, wherein the specific calculation steps of the link duration between node i and the adjacent node j are as follows: Step C1, calculate the distance that node i and node j move from the current time to the next time t as shown in formula (6) and formula (7), respectively. （6） （7） Among them, d i and d j They represent the distances that nodes i and j move from the current moment to the next moment t, respectively, and v i and v j Represent the speed of node i and node j respectively; Step C2, calculate the coordinates of node i and node j at the next time t as shown in formula (8) and formula (9), respectively. ， ， （8） ， ， （9） Among them, x i ,y i 、z i and x j ,y j 、z j Respectively represent the coordinates of node i and node j at the next time t, , and , Respectively represent the angles between the moving directions of nodes i and j, , and They represent the three-dimensional coordinates of node i at the previous moment, , and Respectively represent the three-dimensional coordinates of node j at the previous moment; Step C3, calculate the distance D between node i and node j at the next time t, as shown in formula (10), ， ， ； ， ， ； （10） Among them, a, b, and c represent the components of distance D in the x, y, and z directions, respectively. , and They represent the components of the relative velocity between node i and node j in the x, y, and z directions respectively; Step C4, assuming that the distance between node i and node j at the next time t is R, the link duration time LET between node i and adjacent node j is as shown in formula (11): ， ， ； ； （11） in, , and All indicate set values.

8. The OLSR protocol self-adaptation method under a network topology change environment according to claim 7, characterized in that: Step D, using the link duration between node i and adjacent node j to adjust the MPR selection and path selection of the OLSR protocol, completes the OLSR protocol adaptive adjustment operation, the specific steps are as follows, Step D1, using the link duration between node i and adjacent node j to adjust the MPR selection of the OLSR protocol, the specific steps are as follows: Step D11, normalize the link duration between node i and node j, as shown in formula (12), （12） in, represents the normalized link duration, LET max Indicates the maximum link duration, LET min Indicates the minimum link duration; Step D12, using the normalized link duration The willingness is weighted to complete the adjustment of the MPR selection of the OLSR protocol, as shown in formula (13): （13） in, Indicates the original willingness of the node, represents weighted willingness; Step D2, using the link duration between node i and adjacent node j to adjust the path selection of the OLSR protocol, specifically, using the link duration between node i and node j to weight ETX to complete the path selection of the OLSR protocol, as shown in formula (14), （14） in, represents the weighted ETX, and They represent the forward propagation probability and reverse propagation probability of the link respectively.

9. An OLSR protocol adaptive system under a network topology change environment, wherein the specific operation process of the OLSR protocol adaptive system is based on the OLSR protocol adaptive method according to any one of claims 1 to 8, characterized in that: It includes a link stability adjustment module, a transmission interval adjustment module, a link duration calculation module and an OLSR protocol adjustment module, wherein the link stability adjustment module is used to dynamically adjust the OLSR protocol link stability using a HELLO message; The sending interval adjustment module is used to dynamically adjust the sending interval of the HELLO message by using the node neighbor change rate; The link duration calculation module is used to obtain the HELLO packet received by node i within a HELLO message sending interval, and then use the node geographical location and node speed information in the HELLO packet to calculate the link duration between node i and the adjacent node j; The OLSR protocol adjustment module is used to adjust the MPR selection and path selection of the OLSR protocol by using the link duration between the node i and the adjacent node j, thereby completing the OLSR protocol adaptive adjustment operation.

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