A time synchronization method for motion platforms in a full-duplex system

Abstract

This invention discloses a time synchronization method for motion platforms in a full-duplex system, comprising the following steps: S1. A time reference node and a node to be synchronized send RTT requests Req1 and Req2 to each other at the same local timing; S2. When the time reference node receives the RTT request Req2 from the node to be synchronized, it records the reception time T1; when the node to be synchronized receives the RTT request Req1 from the time reference node, it records the reception time T2; S3. The time reference node sends a feedback message ACK with T1 to the node to be synchronized; S4. After receiving the feedback message ACK with T1, the node to be synchronized calculates the time offset of the clock sources of the two platforms before this synchronization using T1 and T2, thus completing the time synchronization. This invention effectively reduces the time synchronization error introduced by the relative motion between nodes in high-speed motion platforms, improves the time synchronization accuracy between high-speed motion platforms, and reduces the complexity of time synchronization.

Description

Technical Field

[0001] This invention relates to the field of communications, and in particular to a time synchronization method for a motion platform in a full-duplex system. Background Technology

[0002] Full-duplex systems allow two platforms to transmit data bidirectionally simultaneously; typical telephones and mobile phones are full-duplex systems. However, because the transceiver devices used for communication are configured with different crystal oscillators to control the local time of the nodes, different crystal oscillators, even identical crystal oscillators, will develop frequency offsets over time under different physical conditions. The existence of clock offsets may cause collisions between transceiver devices at certain moments during communication. Therefore, a unified time base is needed for the entire network.

[0003] Traditional time synchronization methods between platforms do not take into account the relative motion between platforms, resulting in large time synchronization errors. Time synchronization methods that take into account relative motion have higher computational complexity. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a time synchronization method for motion platforms in a full-duplex system, which effectively improves the time synchronization accuracy between high-speed motion platforms and reduces the complexity of time synchronization.

[0005] The objective of this invention is achieved through the following technical solution: a time synchronization method for a motion platform in a full-duplex system, characterized by comprising the following steps:

[0006] S1. For two motion platforms in a full-duplex communication system, one motion platform is designated as the time reference node and the other motion platform is designated as the synchronization target node; the time reference node and the synchronization target node send RTT requests Req1 and Req2 to each other at the same time when they are timing locally.

[0007] S2. When the time reference node receives the RTT request Req2 sent by the node to be synchronized, it records the reception time. When the synchronization node receives the RTT request Req1 sent by the time reference node, it records the reception time. ;

[0008] S3. The time reference node will bring The ACK feedback information is sent to the time node to be synchronized;

[0009] S4. The time node to be synchronized receives the tape. After receiving the ACK feedback message, through , Calculate the time offset of the clock sources of the two platforms before this synchronization, and complete the time synchronization;

[0010] The time synchronization method further includes step S5:

[0011] Based on the preset relative error threshold, the number of time synchronizations is determined, and steps S1 to S4 are repeated during each time synchronization process to ensure the final time synchronization accuracy.

[0012] The beneficial effects of this invention are: the method proposed in this invention takes into account both time synchronization accuracy and computational complexity, effectively improving the accuracy of time synchronization between platforms and reducing the complexity of time synchronization; and under the premise of maximum relative motion speed, the number of time synchronization operations is solved. As long as the condition of the number of time synchronization operations is met, and as long as the relative motion does not exceed the maximum value of the motion speed, the final relative error is less than the relative error threshold, thereby effectively ensuring the final time synchronization accuracy. Attached Figure Description

[0013] Figure 1 This is a flowchart of the method of the present invention;

[0014] Figure 2 This is a schematic diagram illustrating the principle of high-precision time synchronization between full-duplex motion platforms operating at the same frequency. Detailed Implementation

[0015] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0016] like Figure 1 As shown, a time synchronization method for a motion platform in a full-duplex system includes the following steps:

[0017] S1. For two motion platforms in a full-duplex communication system, one motion platform is designated as the time reference node and the other motion platform is designated as the synchronization target node; the time reference node and the synchronization target node send RTT requests Req1 and Req2 to each other at the same time when they are timing locally.

[0018] S2. When the time reference node receives the RTT request Req2 sent by the node to be synchronized, it records the reception time. When the synchronization node receives the RTT request Req1 sent by the time reference node, it records the reception time. ;

[0019] S201. When the time reference node and the node to be synchronized are synchronized without error, the RTT request transmission times sent by the two nodes should be the same. Let the time difference between the startup of the node to be synchronized and the time reference node be . The node to be synchronized receives the RTT synchronization request Rqe1 sent by the time reference node, and records the time as follows: With the node to be synchronized as the reference frame, its relationship is as follows:

[0020]

[0021] in, The relative velocity between the node to be synchronized and the time reference node. The speed of light;

[0022] S202. The time reference node receives the RTT request Req2 sent by the node to be synchronized, and records the time as... With the node to be synchronized as the reference frame, its relationship is as follows:

[0023] .

[0024] S3. The time reference node will bring The ACK feedback information is sent to the time node to be synchronized.

[0025] S4. After the synchronization node receives the ACK sent by the time reference node, it will... , Subtraction yields the following expression:

[0026]

[0027] in, Taking the world's fastest airplane as an example, its speed is Mach 6.72, approximately 2.286816 kilometers per second, far less than the speed of light. Ignoring the simplifications in the calculation, the clock offset is obtained as follows: The estimated value :

[0028]

[0029] Based on the estimated time offset, the estimated time offset is subtracted from the timer of the node to be synchronized to complete the time synchronization.

[0030] For example, the maximum speed of a fighter jet at high altitude is generally... km / h, substituted get Approximately Then the relative error of time synchronization calculation each time is: As can be seen from the above formula, the larger v is, the larger the error is. Therefore, we take the maximum value of the relative motion rate for calculation. If e is greater than the target accuracy, we only need to perform the above steps multiple times. Otherwise, the time synchronization is completed.

[0031] The time synchronization method further includes step S5:

[0032] Based on the preset relative error threshold, the number of time synchronizations is determined, and steps S1 to S4 are repeated during each time synchronization process to ensure the final time synchronization accuracy.

[0033] S501. Calculate the relative error for each time synchronization:

[0034]

[0035] S502. Due to According to the formula for relative error, the larger v is, the larger the error. Therefore, the maximum known relative velocity between the node to be synchronized and the time reference node is taken. , bring in Calculate the corresponding k, and then calculate the corresponding relative error, that is, the maximum relative error of a single time synchronization, denoted as . ;

[0036] S503. At the maximum relative velocity After n time synchronizations, the final relative error is ,make The relative error is equal to the preset relative error threshold. n is then rounded up to obtain the final number of time synchronizations n1, thus ensuring that the final relative error is less than the relative error threshold under the condition that the maximum speed of motion does not exceed the maximum value.

[0037] S504. After determining the number of time synchronization attempts n1, repeat steps S1 to S4 to complete precise time synchronization.

[0038] In summary, this paper proposes a novel high-precision time synchronization method for simultaneous, full-duplex motion platforms to address the problem of time synchronization between them. This method effectively reduces the time synchronization error introduced by the relative motion between nodes in high-speed motion platforms, improves the time synchronization accuracy, and reduces the complexity of time synchronization.

[0039] The present invention has been described in detail herein with reference to specific embodiments. The description of these embodiments is provided to enable those skilled in the art to make or apply the invention. Various modifications to these embodiments will be readily understood by those skilled in the art. The invention is not limited to these examples or some aspects thereof. The scope of the invention is defined in detail by the appended claims.

[0040] The foregoing description illustrates and describes a preferred embodiment of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A time synchronization method for a motion platform in a full-duplex system, characterized in that: Includes the following steps: S1. For two motion platforms in a full-duplex communication system, one motion platform is designated as the time reference node and the other motion platform is designated as the synchronization target node; the time reference node and the synchronization target node send RTT requests Req1 and Req2 to each other at the same time when they are timing locally. S2. When the time reference node receives the RTT request Req2 sent by the node to be synchronized, it records the reception time. When the synchronization node receives the RTT request Req1 sent by the time reference node, it records the reception time. ; Step S2 includes the following sub-steps: S201. When the time reference node and the node to be synchronized are synchronized without error, the RTT request transmission times sent by the two nodes should be the same. Let the power-on time difference between the node to be synchronized and the time reference node be, i.e., the clock offset. The node to be synchronized receives the RTT synchronization request Rqe1 sent by the time reference node, and records the time as follows: With the node to be synchronized as the reference frame, its relationship is as follows: ； in, The relative velocity between the node to be synchronized and the time reference node. The speed of light; S202. The time reference node receives the RTT request Req2 sent by the node to be synchronized, and records the time as... With the node to be synchronized as the reference frame, its relationship is as follows: ； S3. The time reference node will bring The ACK feedback information is sent to the time node to be synchronized; S4. The time node to be synchronized receives the tape. After receiving the ACK feedback message, through , Calculate the time offset of the clock sources of the two platforms before this synchronization, and complete the time synchronization; In step S4, after the synchronization node receives the ACK sent by the time reference node, it performs... , The relationship is obtained by performing subtraction: ； in, Since it is much smaller than the speed of light, we can ignore it to simplify the calculation, and obtain the clock offset as: The estimated value : ； Based on the estimated time offset, the estimated time offset is subtracted from the timer of the node to be synchronized to complete the time synchronization.

2. The time synchronization method for a motion platform in a full-duplex system according to claim 1, characterized in that: The time synchronization method further includes step S5: Based on the preset relative error threshold, the number of time synchronizations is determined, and steps S1 to S4 are repeated during each time synchronization process to ensure the final time synchronization accuracy.

3. The time synchronization method for a motion platform in a full-duplex system according to claim 2, characterized in that: Step S5 includes the following sub-steps: S501. Calculate the relative error for each time synchronization: ； S502. Due to According to the formula for relative error, the larger v is, the larger the error. Therefore, the maximum known relative velocity between the node to be synchronized and the time reference node is taken. , bring in Calculate the corresponding k, and then calculate the corresponding relative error, that is, the maximum relative error of a single time synchronization, denoted as . ; S503. Maximum relative velocity After n time synchronizations, the final relative error is ,make The relative error is equal to the preset relative error threshold. n is then rounded up to obtain the final number of time synchronizations n1, thus ensuring that the final relative error is less than the relative error threshold under the condition that the maximum speed of motion does not exceed the maximum value. S504. After determining the number of time synchronization attempts n1, repeat steps S1 to S4 to complete precise time synchronization.

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