A dynamic clock synchronization method based on two-way delay calibration

Abstract

The application belongs to the field of communication, and provides a dynamic clock synchronization method based on two-way time delay calibration, which is used to solve the problem of insufficient clock synchronization accuracy between base stations caused by environmental changes and signal transmission time delay fluctuations in the prior art. In the application, the local synchronization signal is sent by the master base station to the slave base station, the slave base station performs synchronization state detection after receiving the synchronization signal, enters the asynchronous state after the detection fails, and returns the asynchronous signal to the master base station; the master base station measures the transmission time delay between the master and slave base stations after receiving the asynchronous signal; at the same time, the environmental parameters of the master and slave base stations are monitored in real time through the environmental sensor, and the environmental compensation correction value is calculated by the master base station according to the environmental parameters of the master and slave base stations; the master base station adjusts the local clock in real time on the basis of the transmission time delay and the environmental compensation correction value, and realizes dynamic clock synchronization; in summary, the clock synchronization accuracy between base stations is significantly improved through two-way time delay calibration and real-time environmental compensation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of communication, and specifically provides a dynamic clock synchronization method based on bidirectional time delay calibration. BACKGROUND

[0002] In the 5G communication system, clock synchronization between base stations is a key factor to ensure network stability and high-precision positioning. Although traditional clock synchronization methods (such as GPS or Beidou satellite time service) can provide relatively accurate clock signals, they are affected by environmental changes (such as temperature fluctuations, air pressure changes, atmospheric interference, etc.) and time delay fluctuations in the signal transmission process, making it difficult to meet the high-precision positioning requirements. In addition, existing clock synchronization technologies have not effectively solved the interference caused by these environmental factors, especially in long-distance and complex environmental signal transmission between base stations.

[0003] Therefore, there is an urgent need for a new clock synchronization technology that can overcome the above problems, provide accurate clock synchronization results, and meet the high-precision requirements between 5G base stations. SUMMARY

[0004] The purpose of the present application is to provide a dynamic clock synchronization method based on bidirectional time delay calibration to solve the problem of insufficient clock synchronization accuracy between base stations caused by environmental changes and signal transmission time delay fluctuations in the prior art. Through bidirectional time delay calibration and environmental compensation mechanism, the present application can eliminate the time delay error caused by environmental factors in real time, significantly improve the clock synchronization accuracy between base stations, and meet the demand of high-precision positioning on the ground.

[0005] To achieve the above purpose, the technical solution adopted by the present application is:

[0006] A dynamic clock synchronization method based on bidirectional time delay calibration, characterized by the following steps:

[0007] Step a: set the initial synchronization state of the slave base station to the synchronization state, and the master base station sends a local synchronization signal to the slave base station;

[0008] Step b: after the slave base station receives the synchronization signal, it performs synchronization state detection. If the detection fails, it enters the asynchronous state and returns an asynchronous signal to the master base station;

[0009] Step c: after the master base station receives the asynchronous signal, it measures the transmission time delay between the master base station and the slave base station based on the bidirectional time delay calibration method;

[0010] Step d: real-time monitoring of the environmental parameters of the master and slave base stations is performed by an environmental sensor, including temperature, humidity, and air pressure. According to the environmental parameters of the master and slave base stations, the master base station calculates the environmental compensation correction value;

[0011] Step e: the master base station adjusts the local clock in real time on the basis of the transmission delay and the environment compensation correction value, to realize dynamic clock synchronization.

[0012] Further, in step b, the specific process of the synchronization state detection is as follows:

[0013] The synchronization signal sent by the master base station to the slave base station is a 1ms rectangular wave signal, the number of pulses of the rectangular wave signal received by the slave base station is intercepted in the same time interval, if the same as the synchronization local signal sent by the master base station, it is determined that the master-slave base station achieves clock synchronization, otherwise, it is determined that the master-slave base station synchronization detection fails.

[0014] Further, in step c, the specific calculation process of the transmission delay is as follows:

[0015] The master base station sends a synchronization request message to the slave base station, and the local timestamp T1 of the master base station is attached in the message; after the slave base station receives the message, the receiving timestamp T2 of the request message is recorded, and the message is returned to the master base station, and the local timestamp T3 of the slave base station is contained in the return message; after the master base station receives the reply message of the slave base station, the receiving timestamp T4 of the reply message is recorded;

[0016] Then the one-way delay of the master base station is calculated as follows:

[0017]

[0018] Where, Δt represents the one-way delay between the master and slave base stations.

[0019] Further, in step d, the environment compensation correction value is as follows:

[0020]

[0021] Where, ΔT comp represents the environment compensation correction value, d represents the distance between the master and slave base stations, c represents the speed of light in vacuum; k T , k H , k P respectively represent the correction coefficients of temperature, humidity, and air pressure on the propagation delay, ΔZ, ΔH, and ΔP respectively represent the change amounts of temperature, humidity, and air pressure between the master reference and the slave base station.

[0022] Further, in step e, the local clock correction value of the master base station is as follows:

[0023] Δt' = Δt + ΔT comp

[0024] Where, Δt' represents the local clock correction value of the master base station.

[0025] The corrected local clock is:

[0026] T' = T - At'

[0027] Where T' represents the master base station after the correction of the local clock, T represents the master base station before the correction of the local clock.

[0028] Based on the above technical solution, the beneficial effects of the present application are:

[0029] The present application provides a dynamic clock synchronization method based on two-way delay calibration, which significantly improves the clock synchronization accuracy between base stations through two-way delay calibration and real-time environment compensation, and can meet the demand of high-precision positioning. At the same time, it can monitor and adapt to environmental changes (such as temperature, humidity, etc.) in real time, effectively eliminate the delay error caused by these factors, and ensure the stability of the clock synchronization accuracy.

[0030] In summary, the present application can cope with the delay fluctuation in complex environment, and through real-time calibration and correction, it can ensure the reliability and stability of clock synchronization, especially suitable for 5G network and high-precision positioning service. Moreover, the present application is not only suitable for 5G communication system, but also can be extended to other communication systems and positioning services that require accurate clock synchronization. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The flowchart of the dynamic clock synchronization method based on two-way delay calibration in the present application.

[0032] Figure 2 The system diagram of master-slave base station in the present application. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and beneficial effects of the present application more clear and explicit, the present application will be further described in detail below in combination with the drawings and examples.

[0034] The present embodiment provides a clock synchronization method based on two-way delay calibration, and its flowchart is shown as Figure 1 Any base station in the communication network has an optical fiber interface connected with its own synchronization base station, and a certain base station is selected as the master base station, and any other base station is directly connected to the master base station, i.e. the slave base station, as shown in Figure 2 In order to realize high-precision clock synchronization, each base station needs to have the following core functional modules:

[0035] High-precision local clock module: The high-precision local clock module is the core of the whole system, and its main function is to generate stable and accurate time signals. Each base station has an internal clock for synchronizing communication events in the network. The clock is initially synchronized through Beidou satellite or other time sources, but the synchronization accuracy is affected by environmental changes and delay fluctuations. After two-way delay calibration, the clock is dynamically adjusted according to the calibration results.

[0036] Bidirectional communication module: bidirectional time delay measurement between base stations through wired communication network (such as optical fiber or dedicated clock synchronization line), this module can exchange time stamp in real time in wired network and measure the round-trip delay of signal propagation;

[0037] Environment monitoring module: the environment monitoring module is used for real-time collection of environmental parameters affecting signal propagation speed, and the base station is equipped with environmental sensors to monitor temperature, humidity, air pressure and other environmental factors affecting time delay and clock stability.

[0038] Specifically, the clock synchronization between any pair of master-slave synchronization base stations is carried out according to the following steps:

[0039] Step a: the initial synchronization state of the slave base station is set to the synchronization state, and the master base station sends the local synchronization signal to the slave base station;

[0040] Step b: after the slave base station receives the synchronization signal, the synchronization state is detected, if the detection fails, the slave base station enters the asynchronous state, and returns the asynchronous signal to the master base station; the specific process of synchronization state detection is:

[0041] The synchronization signal sent by the master base station to the slave base station is a 1ms rectangular wave signal, the number of pulses of the rectangular wave signal received by the slave base station is intercepted in the same time interval, if it is the same as the synchronization local signal sent by the master base station, it is determined that the master-slave base station reaches clock synchronization, otherwise, it is determined that the master-slave base station synchronization detection fails;

[0042] Step c: after the master base station receives the asynchronous signal (i.e. the slave base station enters the asynchronous state), the transmission delay between the master base station and the slave base station is measured based on the bidirectional time delay calibration method; the specific calculation process of the transmission delay is:

[0043] The time delay is measured by accurate time stamp recording, the master base station sends a synchronization request message to the slave base station, and the local time stamp T1 of the master base station is attached in the message; after the slave base station receives the message, the receiving time stamp T2 of the request message is recorded, and the message is returned to the master base station, and the local time stamp T3 of the slave base station is contained in the return message; after the master base station receives the reply message of the slave base station, the receiving time stamp T4 of the reply message is recorded;

[0044] Then the one-way time delay between the master and slave base stations is calculated according to the following formula:

[0045]

[0046] Where Δt represents the one-way time delay between the master and slave base stations;

[0047] T4-T1 represents the total time delay from sending the synchronization request message to receiving the reply message, T3-T2 represents the time delay from receiving the synchronization request message to sending the reply message, by the difference between the above two-way time delay, the master base station can accurately calculate the one-way time delay between the master and slave base stations;

[0048] Step d: real-time monitoring of the environment parameters of the master and slave base stations by the environment sensor, including: temperature, humidity, air pressure; according to the environment parameters of the master and slave base stations, the master base station calculates the environment compensation correction value;

[0049] Considering the influence of environmental changes (such as temperature, humidity, and air pressure fluctuations) on signal propagation time delay, an environment compensation mechanism is designed to correct the propagation time delay, and the environment compensation mechanism is specifically:

[0050] The environment sensor is responsible for real-time monitoring of the environment parameters (temperature, humidity, air pressure) of the master and slave base stations, and the data sampling frequency is set according to the application scenario, generally 1Hz to 10Hz; according to the collected environment data, the propagation time delay compensation value of the signal in the current environment is calculated in real time;

[0051] In the environment compensation model, the expression of the signal propagation time delay affected by the environmental factors is:

[0052]

[0053] Where, ΔT comp represents the environment compensation correction value, d represents the distance between the master and slave base stations, c represents the speed of light in vacuum; k T , k H , k P respectively represent the correction coefficients of temperature, humidity, and air pressure on the propagation time delay, ΔZ, ΔH, and ΔP respectively represent the change (absolute value of difference) of temperature, humidity, and air pressure between the master reference and the slave base station;

[0054] The correction coefficients of temperature, humidity, and air pressure on the propagation time delay k T , k H , k P are known in advance by actual measurement in actual application scenarios; during communication, the propagation time delay correction value is calculated according to real-time environment data;

[0055] Step e: the master base station adjusts the local clock in real time based on the two-way time delay measurement results and the environment compensation correction value, and the correction value is specifically:

[0056] Δt' = Δt + ΔT comp

[0057] Where, Δt' represents the correction value of the local clock of the master base station;

[0058] Then, the corrected local clock is:

[0059] T' = T - Δt'

[0060] Wherein, T' represents the main base station after the correction of local clock, T represents the main base station before the correction of local clock.

[0061] The above description is merely one specific implementation of the application. Any feature in the present description can be replaced by other equivalent or similar features unless otherwise specified. Any feature disclosed in the description or any step in the disclosed method or process can be combined in any manner unless mutually exclusive.

Claims

1. A method for dynamic clock synchronization based on two-way delay calibration, the method comprising: The method comprises the following steps: Step a: from the initial synchronization state of the slave station to the synchronization state, the master station sends a local synchronization signal to the slave station; Step b: after the slave station receives the synchronization signal, the synchronization state is detected, if the detection fails, the slave station enters an asynchronous state, and returns an asynchronous signal to the master station; Step c: after the master station receives the asynchronous signal, the transmission time delay between the master station and the slave station is measured based on a two-way time delay calibration method; the specific calculation process of the transmission time delay is as follows: The master station sends a synchronization request message to the slave station, and the local timestamp T1 of the master station is attached in the message; after the slave station receives the message, the receiving timestamp T2 of the request message is recorded, and the message is returned to the master station, and the local timestamp T3 of the slave station is contained in the returned message; after the master station receives the reply message of the slave station, the receiving timestamp T4 of the reply message is recorded; Then the one-way time delay of the master station is calculated as follows: Wherein, Δt represents the one-way time delay between the master station and the slave station; Step d: the environmental parameters of the master station and the slave station are monitored in real time by the environmental sensor, including temperature, humidity, and air pressure; according to the environmental parameters of the master station and the slave station, the master station calculates the environmental compensation correction value; the environmental compensation correction value is specifically as follows: where ΔT comp represents the environmental compensation correction value, d represents the distance between the master and slave base stations, c represents the speed of light in vacuum; k T , k H , k P respectively represent the correction coefficients of temperature, humidity, and air pressure on the propagation delay, and ΔZ, ΔH, and ΔP respectively represent the change amounts of temperature, humidity, and air pressure between the master base station and the slave base station. Step e: the master station adjusts the local clock in real time based on the transmission time delay and the environmental compensation correction value, and realizes dynamic clock synchronization; the local clock correction value of the master station is specifically as follows: Δt' = Δt + ΔT comp Wherein, Δt' represents the local clock correction value of the master station; The corrected local clock is as follows: T' = T- Δt' Wherein, T' represents the corrected local clock of the master station, and T represents the local clock of the master station before correction.

2. The method of claim 1, wherein the method further comprises: In step b, the specific process of synchronization state detection is as follows: The synchronization signal sent by the master station to the slave station is a 1ms rectangular wave signal, the number of pulses of the rectangular wave signal received by the slave station is intercepted in the same time interval, if it is the same as the synchronization local signal sent by the master station, it is determined that the master station and the slave station achieve clock synchronization, otherwise, it is determined that the master station and the slave station fail to achieve synchronization.

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