Method for improving network synchronization precision

Abstract

The invention relates to the technical field of mobile communication, and provides a method for improving network synchronization precision, which comprises the following steps of: firstly, inputting a distance of a nearest point user of an RU (Remote Unit), and converting the distance into a transmission time delay by using a light velocity, or directly using the transmission time delay 0; thirdly, counting the MSG1 TA measurement value of the user under the RU within a period of time, and subtracting the transmission time delay from the minimum value to obtain the time delay T containing the hardware processing time delay and the optical fiber time delay; and finally, adjusting the frame boundary advance T of the downlink signal of the RU, and compensating the time delay, so that the downlink signals of different RUs reach Tc-level time synchronization. Tc in 5G is about 0.5 ns, so that the synchronization precision reaches 0.5 ns, and the positioning resolution is improved to 0.15 m. According to the method, extra hardware is not needed, the cost is low, the uplink TA measurement value is used for controlling the downlink transmission clock, time delay is effectively compensated, and high-precision network synchronization is achieved.

Description

Technical Field

[0001] The present application belongs to the field of mobile communication transmission technology, and in particular, relates to a method for improving network synchronization accuracy. Background Art

[0002] In 4G and 5G systems, there are more and more private network scenarios that use communication base stations for positioning. A commonly used positioning method is TDOA.

[0003] TDOA uses relative time, that is, by measuring the difference in signal arrival time between the mobile phone and two nearby base stations, to calculate the distance difference between the mobile phone and the base station, thereby avoiding errors caused by the lack of synchronization between the base station and the mobile phone.

[0004] It is similar to the TOA algorithm, but the time estimated at the base station is not the arrival time. , but time difference , indicating that the terminal is Base stations and The difference in transmission delay between base stations. The corresponding main calculation is:

[0005] As can be seen from the formula, there is no essential difference between the TDOA algorithm and the TOA algorithm, but because the base station side estimates the time difference, it will offset part of the synchronization error and measurement error, achieving higher accuracy. In addition, the TDOA positioning algorithm does not require the terminal to maintain time synchronization with the wireless base station, but only requires the base stations to maintain time synchronization.

[0006] Currently, both 5G and 4G are time-synchronized networks. The actual network measurement shows that the time difference of downlink signals from different base stations is between (-2us and 2us). Due to device limitations, RU equipment can usually achieve a time accuracy of 500ns. 8 Meters per second, the positioning accuracy errors are (-600m, 600m), 150m respectively. However, this positioning error caused by network synchronization error is intolerable, and the network synchronization accuracy needs to be improved. Summary of the invention

[0007] An embodiment of the present application provides a method for improving network synchronization accuracy. The present invention aims to improve the time synchronization accuracy of downlink signals sent by different RUs in a 4G / 5G system, thereby improving positioning accuracy.

[0008] The technical solution adopted by the present invention is: The present invention provides a method for improving network synchronization accuracy. First, the transmission delay between the RU and the nearest user is determined by calculating the ratio of the user distance to the speed of light. Then, the TA measurement value of the user MSG1 under the RU is counted, the minimum value is taken and the transmission delay is subtracted to obtain the time delay T including the hardware processing delay and the optical fiber delay; finally, the downlink signal frame boundary of the RU is advanced by T to compensate for the related delay, so as to achieve Tc level time synchronization of downlink signals of different RUs.

[0009] Preferably, the transmission delay is assumed to be zero delay; Count the MSG1 TA values ​​of users under RU for a period of time, take the minimum TA value minus the transmission delay to get the time delay T, where T is the hardware processing delay and fiber delay; The frame boundary of the downlink signal of the RU is adjusted in advance by T to compensate for the hardware processing delay and fiber delay of the RU, so that the downlink signals sent by different RUs can reach the Tc level of time synchronization.

[0010] Preferably, the downlink signal frame boundary of RU is advanced by T, so that the downlink signals sent by different RUs can achieve time synchronization at the Tc (0.5ns) level, thereby achieving a positioning resolution of 0.15m.

[0011] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: Improve the time synchronization accuracy of downlink signals from different RUs in 4G / 5G systems and enhance positioning accuracy.

[0012] No additional hardware required: This method does not require additional hardware equipment and can achieve network synchronization using only the base station equipment itself, thus reducing costs.

[0013] Utilize existing measurement values: By utilizing the upstream TA measurement value to control the downstream transmit clock, compensation for hardware processing delay and fiber delay is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1 It is a flow chart of the method provided in the embodiment of the present application. DETAILED DESCRIPTION

[0016] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0017] The time synchronization of BU comes from GPS time, which is time synchronization. However, due to the different hardware processing delays and fiber delays of the RUs connected to BU, the downlink signals introduce delays, resulting in the downlink signals of different RUs being out of sync, affecting the positioning accuracy. This embodiment provides a method for improving network synchronization accuracy, including: 1) Enter the distance of the nearest user to the RU and convert it to transmission delay using the speed of light; or directly use the transmission delay of 0; The "delay 0" mentioned in the document means that there is no transmission delay between the user and the RU (radio unit) at the closest point, that is, the transmission delay is zero. This is an idealized assumption used to simplify calculations and analysis.

[0018] In actual applications, it takes a certain amount of time for a signal to be transmitted from an RU to a user equipment (UE), and this time is the transmission delay. The size of the transmission delay depends on many factors, such as the distance of signal propagation and the medium. However, in some specific scenarios or idealized models, in order to simplify the problem, it can be assumed that the distance between the nearest user and the RU is very close, so that the transmission delay can be ignored. In this case, "delay 0" is used to represent this situation.

[0019] For example, in the first embodiment, it is mentioned that "the distance of the UE closest to the RU is 0". Here, "distance 0" and "delay 0" correspond to each other. They are both for simplifying the calculation and directly using the TA measurement value to obtain the time delay T without considering the influence of the transmission delay. In this way, the downlink signal frame boundary of the RU can be analyzed and adjusted more intuitively to compensate for the hardware processing delay and the fiber delay, thereby improving the network synchronization accuracy.

[0020] 2) Count the MSG1 TA measurement values ​​of users under RU for a period of time, take the minimum value of the TA measurement value minus the transmission delay to obtain the time delay T, where T is the hardware processing delay and fiber delay; Adjust the RU's downlink signal frame boundary in advance by T to compensate for the RU's hardware processing delay and fiber delay, so that the downlink signals sent by different RUs reach the Tc level of time synchronization; No additional hardware is required, and downlink network synchronization can be achieved using the base station equipment itself.

[0021] The principle is that all network base stations align the GPS clock in the downlink. The uplink RU processing delay and link transmission delay can be theoretically calculated by subtracting the minimum air interface overhead from the uplink measurement value, thus achieving a lower-cost network synchronization method.

[0022] The uplink TA measurement value is used to control the downlink transmission clock. The minimum unit of the TA measurement value is Tc. Therefore, the downlink synchronization accuracy that can be achieved using this method is: the downlink signals sent by different RUs can be synchronized to the Tc (0.5ns) level, so that the positioning resolution can reach Tc (0.5ns)*c = 0.15m.

[0023] First, how far is each transmission tower from its nearest user device (such as a mobile phone). This distance can help us calculate how long it takes for the signal to travel from the transmission tower to the user device, which we call "transmission delay." To simplify the problem, assume that this transmission delay is zero, just like assuming that the user device is at the foot of the transmission tower.

[0024] Observe the TA values ​​of the signals (MSG1) fed back to the transmission tower by all user devices over a period of time. Find the smallest TA value among these values, and then subtract the previously calculated transmission delay to get a special time value T. This T value represents the total time it takes for the transmission tower's own equipment to process the signal and for the signal to be transmitted in the optical fiber.

[0025] Finally, each tower advances its signal transmission time by T, which is like letting the tower "shout" the signal in advance to make up for the time it spends processing and transmitting the signal. Specifically, it reaches the Tc level of time synchronization, which is about 0.5 nanoseconds.

[0026] Embodiment 1 Assuming that the distance of the nearest UE to the RU is 0, the minimum measured value of the terminal msg1 TA within the coverage of the RU for 24 hours is 32Tc. The downlink signal of the RU is advanced by 32Tc based on the GPS clock, where 5G tc = 1 / (4096*480000)s.

[0027] Improved synchronization accuracy: Through the above method, the downlink signals sent by different RUs can achieve Tc-level time synchronization. In 5G, Tc (time unit) = 1 / (4096×480000)s, which is approximately equal to 0.5ns. Therefore, the downlink synchronization accuracy can reach 0.5ns.

[0028] Improved positioning accuracy: Due to the improvement of downlink signal time synchronization accuracy, the positioning resolution reaches Tc (0.5ns) × c (speed of light) = 0.15m. This means that the positioning error is greatly reduced, and the location of the user equipment can be determined more accurately.

[0029] It should be noted that the information interaction, execution process, etc. between the above-mentioned devices / units are based on the same concept as the method embodiment of the present application. Their specific functions and technical effects can be found in the method embodiment part and will not be repeated here.

[0030] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application implements all or part of the processes in the above-mentioned embodiment method, which can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may at least include: any entity or device that can carry the computer program code to the camera / terminal device, recording medium, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium. For example, a USB flash drive, a mobile hard disk, a magnetic disk or an optical disk. In some jurisdictions, according to legislation and patent practice, computer-readable media cannot be electric carrier signals and telecommunication signals.

[0031] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0032] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0033] In the embodiments provided in the present application, it should be understood that the disclosed devices / network equipment and methods can be implemented in other ways. For example, the device / network equipment embodiments described above are merely schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0034] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0035] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for improving network synchronization accuracy, characterized in that: First, determine the transmission delay between the RU and the nearest user by calculating the ratio of the user distance to the speed of light. Then, count the TA measurement values ​​of user MSG1 under the RU, take the minimum value and subtract the transmission delay to obtain the time delay T including the hardware processing delay and the fiber delay. Finally, advance the downlink signal frame boundary of the RU by T to compensate for the related delay and achieve Tc-level time synchronization of the downlink signals of different RUs.

2. The method according to claim 1, characterized in that The transmission delay is assumed to be zero delay; Count the MSG1 TA values ​​of users under RU for a period of time, take the minimum TA value minus the transmission delay to get the time delay T, where T is the hardware processing delay and fiber delay; The frame boundary of the downlink signal of the RU is adjusted in advance by T to compensate for the hardware processing delay and fiber delay of the RU, so that the downlink signals sent by different RUs can reach the Tc level of time synchronization.

3. The method according to claim 1, characterized in that The downlink signal frame boundary of RU is advanced by T, so that the downlink signals sent by different RUs can achieve time synchronization at the Tc level of 0.5ns, thereby achieving a positioning resolution of 0.15m.

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