CN111934841B

CN111934841B - Method and device for determining reference clock, system, storage medium and electronic device

Info

Publication number: CN111934841B
Application number: CN202011006095.XA
Authority: CN
Inventors: 吴涛; 沈杰; 陈高强; 张静静; 马超
Original assignee: Sunwave Communications Co Ltd
Current assignee: Sunwave Communications Co Ltd
Priority date: 2020-09-23
Filing date: 2020-09-23
Publication date: 2021-01-22
Anticipated expiration: 2040-09-23
Also published as: CN111934841A; WO2022062308A1

Abstract

The invention provides a method, a device, a system, a storage medium and an electronic device for determining a reference clock, wherein the method comprises the following steps: for each remote in the target loop, determining each remote as a current remote when: acquiring a first signal received by a first port of a current remote terminal from a target loop and a second signal received by a second port of the current remote terminal from the target loop; according to the first signal and the second signal, determining that one port of a first port and a second port of the current remote machine is a slave port and the other port of the first port and the second port is a master port; and determining the reference clock of the current remote machine according to the signal received by the slave port of the current remote machine from the target loop. The invention solves the technical problem that the increase of the cascade stage number of the far-end equipment in the loop leads to the increase of the phase noise of the reference clock of the far-end equipment in the loop.

Description

Method and device for determining reference clock, system, storage medium and electronic device

Technical Field

The present invention relates to the field of communications, and in particular, to a method, an apparatus, a system, a storage medium, and an electronic apparatus for determining a reference clock.

Background

The distributed coverage system includes a base station, a near-end Unit (referred to as an Access Unit, referred to as AU for short), a Remote Unit (referred to as Remote Unit, referred to as RU for short), and other devices, where each device includes a transmitter, a receiver, and a Digital Pre-Distortion (DPD) feedback path. Various transmitters and receivers, such as the ADC/DAC included therein and Local Oscillators (LOs) require reference clocks with low jitter and phase noise to improve performance, since the phase noise and jitter performance of the clock generator can have a serious impact on the dynamic range and linearity performance of the data Converter, which in turn affects the Error Vector Magnitude (EVM) indicator of the transmitter/receiver and further affects the signal transmission rate.

Clock sources for synchronization between base stations are usually derived from a Global Positioning System (GPS), and clock sources for synchronization between devices such as AU or RU are derived from a Common Radio Interface (CPRI) link. GPS has excellent long-term frequency stability; the RU and other devices need to recover a clock from the CPRI link and use the clock as a reference clock of the local clock chip, and the recovered clock is degraded by phase Noise and jitter with respect to a reference clock of a previous device, so that the recovered clock is a poor reference clock, which may cause phase Noise of the LO to increase, and further increase transmission/reception EVM and Signal to Noise Ratio (SNR). Moreover, high clock jitter and noise floor can reduce the system SNR and cause Spurious radiation from the data converter, further reducing the Spurious-free Dynamic Range (SFDR) of the data converter, and thus the low performance clock source ultimately results in reduced system capacity and throughput.

In the related art, the networking mode of the distributed coverage system includes star, chain, and mixed modes of star and chain. Generally, a networking mode requires a loop protection function, that is, a near-end machine and a plurality of far-end machines are connected in series to form a loop, however, the more far-end machines are connected in the loop in series, the greater the clock phase noise of the far-end machine at the last stage is, and the greater the degradation of the EVM is. As shown in fig. 1, on the physical connection of the loop, the a port of the AU is connected to RU1, RU1 is connected to RU2, … … is connected to RU7 and RU8, and RU8 is connected to the D port of the AU. For each RU, its slave port (also called S port) is used to receive the downstream signal from the previous device in the loop and transfer the received downstream signal to the master port (also called M port) of the RU, and the M port is used to transfer the downstream signal transferred from the S port to the next device in the loop. In the networking mode of fig. 1, paths through which downlink signals pass are an a port, RU1, RU2 … … RU7, and RU 8. Each RU device recovers a clock signal from a signal (e.g., a signal based on the CPRI protocol) received in the loop according to its S port, and transmits the recovered clock signal to a local clock chip as a reference clock. As the number of RU devices in the loop increases, RU devices in the loop, such as RU8 in fig. 1, are at the last stage of signal transmission and are also at the last stage of clock recovery, so RU8 is the most noisy according to the clock phase received from its S port, resulting in a corresponding degradation of the EVM of the clock phase signal of RU8, thereby affecting the signal transmission rate.

In the related art, an effective technical scheme is not provided yet for the technical problem that the increase of the cascade stage number of the far-end equipment in the loop leads to the increase of the phase noise of the reference clock of the far-end equipment in the loop.

Disclosure of Invention

The embodiment of the invention provides a method, a device, a system, a storage medium and an electronic device for determining a reference clock, which are used for at least solving the technical problem that the increase of the cascade stage number of remote equipment in a loop causes the increase of the phase noise of the reference clock of the remote equipment in the loop.

According to an embodiment of the present invention, there is provided a method for determining a reference clock, including: performing the following for each remote machine in the target loop, wherein each remote machine is determined to be the current remote machine when the following are performed for that remote machine: acquiring a first signal received by a first port of the current remote-end machine from the target loop and a second signal received by a second port of the current remote-end machine from the target loop, wherein the target loop comprises: a loop consisting of a near-end unit and a plurality of far-end units; according to the first signal and the second signal, determining that one of the first port and the second port of the current remote machine is a slave port and the other one of the first port and the second port is a master port; and determining the reference clock of the current remote machine according to the signal received by the slave port of the current remote machine from the target loop.

Optionally, before the performing, for each remote machine in the target loop, the following: respectively sending a first signal and a second signal to the target loop through a first port of the near-end machine and a second port of the near-end machine, where the first signal is transmitted in the target loop according to a first signal transmission path, the second signal is transmitted in the target loop according to a second signal transmission path, the first signal sent by the near-end machine carries first identification information and second identification information, the first identification information is used to represent the first port of the near-end machine, the second identification information is used to represent that the number of far-end machines through which the first signal passes in the target loop is an initial value, the second signal sent by the near-end machine carries third identification information and fourth identification information, the third identification information is used to represent the second port of the near-end machine, and the fourth identification information is used to represent the number of far-end machines through which the second signal passes in the target loop The number is the initial value.

Optionally, after the acquiring a first signal received by the first port of the present remote unit from the target loop and a second signal received by the second port of the present remote unit from the target loop, the method further includes: receiving the first signal from a first device connected to the current remote machine through a first port of the current remote machine and receiving the second signal from a second device connected to the current remote machine through a second port of the current remote machine, wherein the first device is a device in the target loop connected to the first port of the current remote machine and the second device is a device in the target loop connected to the second port of the current remote machine; after a value represented by second identification information carried in the first signal received by the current remote terminal is increased by a preset value, updated second identification information is obtained, and after a value represented by fourth identification information carried in the second signal received by the second port of the current remote terminal is increased by the preset value, updated fourth identification information is obtained; updating second identification information in the first signal received by the current remote terminal by using the updated second identification information to obtain an updated first signal, and sending the updated first signal to the second device through a second port of the current remote terminal; and updating fourth identification information in the second signal received by the current remote terminal by using the updated fourth identification information to obtain an updated second signal, and sending the updated second signal to the first device through the first port of the current remote terminal.

Optionally, the determining, according to the first signal and the second signal, that one of the first port and the second port of the current remote machine is a slave port and the other of the first port and the second port is a master port includes: acquiring first identification information and second identification information carried in the first signal, and third identification information and fourth identification information carried in the second signal, wherein the second identification information is used for indicating the number of remote terminals passed by the first signal in the target loop, and the fourth identification information is used for indicating the number of remote terminals passed by the second signal in the target loop; in a case where the first identification information represents one port of the near-end machine and the third identification information represents another port of the near-end machine, in a case where a value represented by the second identification information is less than or equal to a value represented by the fourth identification information, determining the first port of the current far-end machine as a slave port of the current far-end machine and determining the second port of the current far-end machine as a master port of the current far-end machine; in a case where the first identification information represents the one port of the near-end machine and the third identification information represents the other port of the near-end machine, in a case where a value represented by the second identification information is larger than a value represented by the fourth identification information, determining the second port of the current remote machine as a slave port of the current remote machine, and determining the first port of the current remote machine as a master port of the current remote machine.

Optionally, the determining a reference clock of the current remote unit according to a signal received from the target loop by a slave port of the current remote unit includes: acquiring a signal received by the current remote terminal from a device connected with a slave port of the current remote terminal in the target loop; recovering a clock signal according to the signal received from the equipment connected with the slave port of the current remote terminal in the target loop; and determining the recovered clock signal as a reference clock of the current remote terminal.

Optionally, the determining, according to the first signal and the second signal, that one of the first port and the second port of the current remote machine is a slave port and the other of the first port and the second port is a master port includes: determining that a first remote terminal fails when a signal sent by a second remote terminal connected with a master port of a current remote terminal is received by the current remote terminal and a signal sent by the first remote terminal connected with a slave port of the current remote terminal is not received by the current remote terminal within a preset time period; switching the slave port of the current remote machine and the master port of the current remote machine, wherein the plurality of remote machines further include the first remote machine and the second remote machine.

According to another embodiment of the present invention, there is provided a reference clock determining apparatus including: an obtaining module, a first determining module and a second determining module, wherein the device is configured to determine, by the obtaining module, the first determining module and the second determining module, a reference clock of each remote unit in a target loop, wherein when the reference clock of each remote unit is determined, each remote unit is determined as a current remote unit: wherein the obtaining module is configured to obtain a first signal received by a first port of the current remote end from the target loop, and a second signal received by a second port of the current remote end from the target loop, where the target loop includes: a loop consisting of a near-end unit and a plurality of far-end units; the first determining module is configured to determine, according to the first signal and the second signal, that one of the first port and the second port of the current remote machine is a slave port, and the other of the first port and the second port is a master port; and the second determining module is used for determining the reference clock of the current remote machine according to the signal received by the slave port of the current remote machine from the target loop.

According to another embodiment of the present invention, there is provided a system for determining a reference clock, including: a near-end machine and a plurality of remote machines, wherein each of the plurality of remote machines is configured to perform the following operations, wherein each of the plurality of remote machines determines itself as a current remote machine when performing the following operations: acquiring a first signal received by a first port of the current remote-end machine from the target loop and a second signal received by a second port of the current remote-end machine from the target loop, wherein the target loop comprises: a loop consisting of the near-end machine and the plurality of far-end machines; according to the first signal and the second signal, determining that one of the first port and the second port of the current remote machine is a slave port and the other one of the first port and the second port is a master port; and determining the reference clock of the current remote machine according to the signal received by the slave port of the current remote machine from the target loop.

With the present invention, the following operations are performed for each remote in the target loop, wherein each remote is determined to be the current remote when the following operations are performed for the each remote: acquiring a first signal received by a first port of the current remote-end machine from the target loop and a second signal received by a second port of the current remote-end machine from the target loop, wherein the target loop comprises: a loop consisting of a near-end unit and a plurality of far-end units; according to the first signal and the second signal, determining that one of the first port and the second port of the current remote machine is a slave port and the other one of the first port and the second port is a master port; and determining the reference clock of the current remote machine according to the signal received by the slave port of the current remote machine from the target loop. Therefore, the technical problem that the increase of the cascade stage number of the far-end equipment in the loop leads to the increase of the phase noise of the reference clock of the far-end equipment in the loop can be solved, the phase noise of the reference clock of the far-end equipment caused by the increase of the cascade stage number of the far-end equipment is reduced, and the deterioration degree of the transmission/reception error vector magnitude of the system is reduced.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:

FIG. 1 is a diagram illustrating a method for determining a reference clock in the related art;

FIG. 2 is a flow chart of a method for reference clock determination according to an embodiment of the invention;

FIG. 3 is a network topology diagram of a method for reference clock determination according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of loop protection according to another embodiment of the present invention;

FIG. 5 is a schematic diagram of loop protection according to yet another embodiment of the present invention;

fig. 6 is a block diagram of a reference clock determination apparatus according to another embodiment of the present invention;

fig. 7 is a schematic structural diagram of an alternative electronic device according to an embodiment of the invention.

Detailed Description

The invention will be described in detail hereinafter with reference to the accompanying drawings in conjunction with embodiments. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.

An embodiment of the present invention provides a method for determining a reference clock, and fig. 2 is a flowchart of the method for determining a reference clock according to the embodiment of the present invention, in which the following operations from step S102 to step S106 are performed for each remote terminal in a target loop, where each remote terminal is determined as a current remote terminal when the following operations are performed for each remote terminal:

step S102, obtaining a first signal received by a first port of the current remote terminal from the target loop, and a second signal received by a second port of the current remote terminal from the target loop, where the target loop includes: a loop consisting of a near-end unit and a plurality of far-end units;

step S104, according to the first signal and the second signal, determining that one port of the first port and the second port of the current remote machine is a slave port and the other port of the first port and the second port is a master port;

step S106, determining the reference clock of the current remote machine according to the signal received by the slave port of the current remote machine from the target loop.

In the above embodiment, the first port of each remote unit receives the first signal from the target loop and the second port receives the second signal from the target loop, that is, there is a bidirectional signal transmission path in the target loop.

The method in the above embodiment may be applied to the network topology shown in fig. 3, as shown in fig. 3, the near-end unit AU transmits a first signal to the target loop through its first port (i.e. port a in fig. 3), and transmits a second signal to the target loop through its second port (i.e. port D in fig. 3), where the target loop is a loop composed of the AU and the far-end units RU1 to RU 8. With the above embodiment, the slave port and the master port of each of the plurality of remote machines shown in fig. 3 can be determined.

In the above embodiment, for the current remote unit (i.e. any one of the remote units in the target loop), taking the remote unit RU1 in fig. 3 as an example, after the first port (i.e. port 1) of the RU1 receives the first signal from the target loop (i.e. the AU in the target loop), the second identification information identifier value carried in the first signal is updated, that is, the value of the second information identifier is increased by a preset value (e.g. 1), and the first signal after updating the second identification information is transferred to the second port (i.e. port 2) of the RU1, and the second port continues to transmit the updated first signal to the next device (i.e. RU2) connected to the second port in the target loop; the first port of RU2 receives the first signal and then performs the same processing as that performed in RU1, i.e. adds 1 to the value identified by the second identification information in the received signal, and continues to transmit to the next device connected to RU1 until the second port of the AU receives the signal transmitted by RU 8; and the second port of the AU transmits the second signal to the target loop, each remote terminal in the target loop receives the second signal through the first port, and the remote terminal also adds 1 to the value indicated by the fourth identification information in the second signal to obtain an updated second signal, and then transmits the updated second signal through the second port to the next device connected to the second port, for example, after the first port of RU8 receives the second signal transmitted by the D port of the AU, the first port of RU8 transmits the updated second signal to the next device connected to the second port of RU8 in the target loop, until the first port of the AU receives the updated second signal transmitted by RU 1. Taking as an example that the first identification information carried in the first signal sent by the a port of the AU is a (the content of the first identification information may be "a" expressed in hexadecimal form), the second identification information represents a value of 0, the third identification information carried in the first signal sent by the D port of the AU is D, and the fourth identification information represents a value of 0: the first signal received by the first port of RU1 carries "a 1", the first signal received by RU2 from RU1 carries "a 2", and the first signal received by the D port of … … AU from RU8 carries "a 9"; the second signal received by the second port of RU8 carries "D1", the second signal received by RU7 from RU8 carries "D2", and the second signal received by the a port of … … AU from RU1 carries "D9".

In the above embodiment, in a case where the first identification information carried in the first signal indicates one port (e.g., the first port a) of the near-end machine and the third identification information carried in the second signal indicates another port (e.g., the second port D) of the near-end machine, it may be determined that there is no device having a fault in the target loop in which the current remote machine is located, and in a case where a value indicated by the second identification information is less than or equal to a value indicated by the fourth identification information, it is determined that the number of remote machines between the first port of the current remote machine and the one port of the near-end machine in the target loop is less than or equal to the number of remote machines between the second port of the current remote machine and another port of the near-end machine; and the value represented by the second identification information in the first signal received by the current remote machine is also used to represent the position serial number of the current remote machine on the signal transmission path of the first signal in the target loop (i.e. it represents that the current remote machine is the next remote machine on the signal transmission path of the first signal), and the value represented by the fourth identification information in the second signal received by the current remote machine is also used to represent the position serial number of the current remote machine on the signal transmission path of the second signal in the target loop (i.e. it represents that the current remote machine is the next remote machine on the signal transmission path of the second signal).

The above embodiments may be used in a distributed coverage system, that is, the near-end machine and the plurality of remote machines in the above embodiments are all devices in the distributed coverage system. The method in the above embodiment is applied to any one of the plurality of remote machines, that is, the above operation is performed on each of the plurality of remote machines, so that each remote machine determines, according to the first signal and the second signal respectively received by the first port and the second port from the target loop, a position serial number of itself in a signal transmission path of the first signal, and a position serial number of itself in a signal transmission path of the second signal, thereby determining a slave port and a master port of itself; because each remote machine determines the reference clock according to the signal received from the port from the target loop (i.e. recovers the clock from the received signal and provides the clock as the reference clock to the local clock chip), the embodiments can reduce the number of signal transmission stages in the clock recovery process of the target loop, reduce the number of cascade stages of clock recovery of the target loop, prevent the deterioration of clock phase noise, and further avoid the deterioration of the system EVM.

It should be noted that, because the current remote terminal is connected to the first remote terminal through the slave port thereof, that is, it indicates that the current remote terminal determines the reference clock according to the signal received from the first remote terminal, when the first remote terminal fails, the current remote terminal cannot receive the signal from the first remote terminal any more, and at this time, the slave port of the current remote terminal and the master port of the current remote terminal need to be switched (that is, the slave port and the master port are switched, for example, the first port of the current remote terminal is a slave port, the second port is a master port, and after the switching, the first port of the current remote terminal is determined as a master port, and the second port is determined as a slave port).

Optionally, after the switching the slave port of the current remote end machine and the master port of the current remote end machine, the method further includes: and determining the reference clock of the current remote machine according to the signal received by the current slave port of the current remote machine from the second remote machine.

Optionally, after the switching the slave port of the current remote end machine and the master port of the current remote end machine, the method further includes: sending a third signal to the target loop through a current slave port of the current remote terminal, wherein the third signal carries fifth identification information and sixth identification information, the fifth identification information is used for indicating that the target loop is in fault, and a value indicated by the sixth identification information is used for indicating an initial value; under the condition that each remote machine in a first remote machine set of the plurality of remote machines receives the third signal sent by the current remote machine, determining that the target loop has a fault according to the fifth identification information carried in the third signal, keeping a master port and a slave port of the remote machine unchanged, and sending the third signal to a third device connected with a slave port of the remote machine through the slave port of the remote machine, wherein the first remote machine set comprises the second remote machine, and the third device is a next remote machine or a near-end machine connected with the slave port of the remote machine.

Optionally, the fifth identification information is further used to indicate that the device in the target loop that has failed is the first remote machine.

Optionally, each remote terminal in the first remote terminal set, when receiving the third signal through its own main port, further updates a value indicated by sixth identification information in the third signal to obtain an updated third signal, and sends the updated third signal to a next remote terminal or a near-end terminal connected to itself.

As shown in fig. 4, after the RU6 (i.e. the first remote unit in the above embodiment) fails, the RU5 (i.e. the current remote unit in the above embodiment) switches the master port and the slave port, and sends the third data to the target loop (in this case, the path formed by the a ports of RU4, RU3, RU2, RU1 and AU) through the current slave port (i.e. port 1 of RU 5), the RU4, after receiving the third signal, updates the sixth representation information therein and then sends the updated sixth representation information to the RU3 connected thereto, and the RU3, after receiving the third data from the RU4, performs the same processing operation as that of the RU4 until the a port of the AU receives the third data sent by the RU 1.

Optionally, the method further comprises: maintaining a master port and a slave port of a third remote unit unchanged, wherein the master port of the third remote unit is connected to the first remote unit, and the plurality of remote units includes the third remote unit; sending a fourth signal to the target loop through a slave port of the third remote terminal, where the fourth signal carries seventh identification information and eighth identification information, the seventh identification information is used to indicate that the target loop has a fault, and the eighth identification information is used to indicate an initial value; under the condition that each remote machine in a second remote machine set in the plurality of remote machines receives the fourth signal, determining that the target loop has a fault according to seventh identification information carried in the fourth signal, and keeping a main port and a slave port of each remote machine unchanged; and transmitting the fourth signal to a fourth device connected with the slave port of the fourth device through the slave port of the fourth device, wherein the fourth device is a next remote machine or a near-end machine connected with the slave port of the fourth device.

Note that, in the above-described embodiment, the initial value may be 1.

As shown in fig. 5, RU7 connected to the slave port of RU6 performs the same operation as RU5, that is, RU7 transmits a fourth signal to the target loop (in this case, a path made up of RU8, the D port of AU), similarly to the operation performed by RU5 connected to the master port of RU 6. The master port and the slave port of RU5 are inverted, and the master port and the slave port of RU1 to RU4, and the master port and the slave port of RU7 and RU8 are all kept unchanged.

The following explains the method for determining the reference clock in the above embodiment with an example, but is not intended to limit the technical solution of the embodiment of the present invention.

As shown in fig. 3, the target loop is a loop composed of a first port of the AU (i.e., a port), RU1, RU2 … … RU8, and a second port of the AU (i.e., D port).

In this embodiment of the present invention, the downlink signal flow includes two paths, and each RU detects a position of itself in the loop through signals received from the two paths, specifically: the a port of the AU transfers a first signal carrying fixed identification information (i.e., the first identification information and the second identification information in the above-mentioned embodiment) id (e.g., a1, where "a" is the first identification information and is used to represent the a port of the AU, and "1" is a value represented by the second identification information) to the 1 port of RU1 (i.e., the first port in the above-mentioned embodiment), and RU1 automatically adds 1 to the value of the second identification information carried in the first signal (i.e., a1 becomes a2) after the 1 port receives the first signal, and transfers the value to RU2 through the 2 port; the 1 port of RU2 receives the first signal carrying a2 transmitted by the 2 port of RU1, and after automatically adding 1, transmits the first signal carrying A3 to RU3 through the 2 port, and so on, the first signal received by RU1 carries a1, the second signal received by RU2 carries a2, the first signal received by … … RU8 carries A8, and the first signal received by the D port of AU carries a 9.

The D port of the AU transmits the second signal carrying D1 in the same way, and RU8 … … RU1 processes the received second signal in a similar way to the received first signal, so that the second signal received by RU8 carries D1, the second signal received by RU7 carries D2, the second signal received by RU … … RU1 carries D8, and the second signal received by the a port of the AU carries D9.

It should be noted that, the signal received by the remote unit in the embodiment of the present invention refers to a signal received by the remote unit through one port of the remote unit from a device (i.e., the remote unit or the near-end unit) in the target loop directly connected to the port.

Thus, for RU 1: the port 1 receives a signal carrying A1, the port 2 receives a signal carrying D8, and the RU1 is determined to be in a loop of the AU connected with the port A and the port D according to values indicated by second identification information and fourth identification information in the two signals; and according to the serial number values in the two signals, determining that the RU1 is the 1 st device connected under the A port of the AU and the 8 th device connected under the D port of the AU, so that the RU1 sets the 1 port as the S port and the 2 port as the M port, and the flow direction of the downlink signal flows from the 1 port to the 2 port and is transmitted to the RU2 continuously. The clock recovery process is that RU1 obtains a recovered clock from the data stream through a SERializer/DESerializer (serdes) of the S-port and provides the recovered clock to the clock chip of RU1 as a local reference clock.

Therefore, RU1, RU2, RU3 and RU4 know that they are closer to the a port in the loop topology and set their slave ports, so that the number of signal transmission stages under the a port link is only 4 stages. Similarly, RU5, RU6, RU7, and RU8 know that they are the closest D-port in the loop topology, and set their slave ports, so that the number of signaling stages in the D-port link is only 4. That is, in the above embodiment, two paths included in the downstream signal flow shown in fig. 3 are formed, that is: the path composed of the A port, RU1, RU2, RU3 and RU4 of the near-end machine AU and the path composed of the D port, RU8, RU7, RU6 and RU5 of the AU reduce the cascade stage number of clock recovery in the loop by half, thereby preventing EVM deterioration caused by clock phase noise deterioration due to excessive cascade equipment number and optimizing signal coverage.

Through the embodiment, the signal transmission stage number of the previous clock recovery in the loop topology is 8 stages, namely, the signal transmission stage number is 8-stage cascade stage number, and now the signal transmission stage number is changed into the cascade stage number with only 4 stages, so that the phase noise of the recovered clock is greatly superior to the noise condition before the loop topology, the performance of the EVM is improved to a certain extent, and the transmission rate and the coverage range of the signal are optimized. As shown in fig. 3, the number of signal transmission stages of clock recovery in the loop topology becomes a 4-stage cascade stage, that is, the number of cascade stages of RU1 to RU4 in fig. 3 is 4, and the number of cascade stages of RU8 to RU5 is also 4.

As shown in fig. 4, in the above method according to the embodiment of the present invention, loop protection may also be implemented, where when a fault occurs in a middle RU (e.g. RU6 in fig. 4), since the port 1 of the RU5 cannot obtain optical fiber synchronization with the RU6, identification information (id) on the port 1 is set to f1 (where fifth identification information f is used to indicate that there is a faulty device in the loop, and 1 is a value identified by sixth identification information; optionally, the fifth identification information f is also used to indicate the RU6 (i.e. the first remote terminal in the above embodiment has a fault) and return a third signal carrying f1 to the RU4, and the third signal received by the RU4 carries the third signal carrying f4 received by the f1 … … RU1 and the f5 received by the port a.

RU7 also transmits a fourth signal, where the fourth signal received by RU8 carries f1 and the fourth signal received by port D carries f 2.

At this time, for RU 1: when port 1 receives a1 and port 2 receives f4, RU1 knows that there is a failed device in the loop, and when RU1 is in the unidirectional link under port a and is the 1 st device under port a, there are 4 devices in the unidirectional link after RU 1. RU1 keeps its S and M ports unchanged, and downstream signals flow from 1 port to 2 port and continue to be transmitted to RU 2. The clock recovery process is that RU1 obtains a recovered clock from the data stream through a SERializer/DESerializer (serdes) of the S-port and provides the recovered clock to the clock chip of RU1 as a local reference clock.

Thus, RU1, RU2, RU3, RU4, and RU5 know that they are closer to the a-port in the loop topology, and thus the number of signaling steps for clock recovery under the a-port link is only 5 steps. Similarly, RU7, RU8 know that they are the closest in the loop topology to port D, so that the number of signaling stages for clock recovery under the port D link is only 2. Through the embodiment, topology information of the target loop can be obtained by the AU and each RU, so that the situation that the RU6 has a fault is positioned, and a loop protection function is realized.

It should be noted that the first signal, the second signal, the third signal and the fourth signal in the above embodiments may be signals based on a CPRI protocol, that is, between the AU and the RUs 1 and RU8, and between the RUs communicate with each other through the CPRI protocol, thereby forming a CPRI link.

It should be noted that, in the above embodiment, the first identification information, the third identification information, the fifth identification information, and the seventh identification information may be a first field in a signal based on the CPRI protocol, that is, one field in which the first identification information, the third identification information, and the fifth identification information may be the same, and when the near-end machine transmits a signal, a value of the field may be set to indicate a port that transmits the signal, or, when there is a failed remote machine in the target loop, another remote machine directly connected to the failed remote machine may generate a signal, and set a value of the field of the signal to indicate that a failure occurs; the second identification information, the fourth identification information, the sixth identification information, and the eighth identification information may be a second field in the signal based on the CPRI protocol, that is, the second identification information, the fourth identification information, the sixth identification information, and the eighth identification information may be the same field, the value of the field may be set to an initial value (for example, 1) when the near-end unit transmits the signal, and when each far-end unit receives the signal from the device connected thereto, the value indicated by the field of the signal is updated, and the updated information is continuously transmitted to the next device connected thereto.

Through the above description of the embodiments, those skilled in the art can clearly understand that the method according to the above embodiments can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware, but the former is a better implementation mode in many cases. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which is stored in a storage medium (e.g., ROM/RAM, magnetic disk, optical disk) and includes instructions for enabling a terminal device (e.g., a mobile phone, a computer, a server, or a network device) to execute the method according to the embodiments of the present invention.

According to another embodiment of the present invention, there is provided a device for determining a reference clock, which is used to implement the foregoing embodiments and preferred embodiments, and which has been described above and will not be described again. As used below, the term "module" may be a combination of software and/or hardware that implements a predetermined function. Although the means described in the embodiments below are preferably implemented in software, an implementation in hardware, or a combination of software and hardware is also possible and contemplated.

Fig. 6 is a block diagram of a reference clock determining apparatus according to another embodiment of the present invention, which includes an obtaining module 72, a first determining module 74 and a second determining module 76, and is configured to determine, by the obtaining module 72, the first determining module 74 and the second determining module 76, a reference clock of each remote machine in a target loop, where when determining the reference clock of each remote machine, each remote machine is determined as a current remote machine:

the obtaining module 72 is configured to obtain a first signal received by a first port of the current remote end from the target loop, and a second signal received by a second port of the current remote end from the target loop, where the target loop includes: a loop consisting of a near-end unit and a plurality of far-end units;

the first determining module 74 is configured to determine, according to the first signal and the second signal, that one of the first port and the second port of the current remote machine is a slave port, and the other of the first port and the second port is a master port;

the second determining module 76 is configured to determine the reference clock of the current remote unit according to the signal received from the target loop by the slave port of the current remote unit.

Optionally, the apparatus further includes a sending module, configured to send a first signal and a second signal to the target loop through a first port of the near-end machine and a second port of the near-end machine, respectively, before determining a reference clock of each far-end machine in the target loop, where the first signal is transmitted in the target loop according to a first signal transmission path, the second signal is transmitted in the target loop according to a second signal transmission path, the first signal sent by the near-end machine carries first identification information and second identification information, the first identification information is used to represent the first port of the near-end machine, the second identification information is used to represent that the number of far-end machines that the first signal passes through in the target loop is an initial value, and the second signal sent by the near-end machine carries third identification information and fourth identification information, the third identification information is used to indicate the second port of the near-end unit, and the fourth identification information is used to indicate that the number of far-end units through which the second signal passes in the target loop is the initial value.

Optionally, the obtaining module 72 is further configured to: receiving the first signal from a first device connected to the current remote machine through a first port of the current remote machine and receiving the second signal from a second device connected to the current remote machine through a second port of the current remote machine, wherein the first device is a device in the target loop connected to the first port of the current remote machine and the second device is a device in the target loop connected to the second port of the current remote machine; after a value represented by second identification information carried in the first signal received by the current remote terminal is increased by a preset value, updated second identification information is obtained, and after a value represented by fourth identification information carried in the second signal received by the second port of the current remote terminal is increased by the preset value, updated fourth identification information is obtained; updating second identification information in the first signal received by the current remote terminal by using the updated second identification information to obtain an updated first signal, and sending the updated first signal to the second device through a second port of the current remote terminal; and updating fourth identification information in the second signal received by the current remote terminal by using the updated fourth identification information to obtain an updated second signal, and sending the updated second signal to the first device through the first port of the current remote terminal.

Optionally, the obtaining module 72 is configured to: acquiring first identification information and second identification information carried in the first signal, and third identification information and fourth identification information carried in the second signal, wherein the second identification information is used for indicating the number of remote terminals passed by the first signal in the target loop, and the fourth identification information is used for indicating the number of remote terminals passed by the second signal in the target loop; the first determining module 74 is further configured to: in a case where the first identification information represents one port of the near-end machine and the third identification information represents another port of the near-end machine, in a case where a value represented by the second identification information is less than or equal to a value represented by the fourth identification information, determining the first port of the current far-end machine as a slave port of the current far-end machine and determining the second port of the current far-end machine as a master port of the current far-end machine; in a case where the first identification information represents the one port of the near-end machine and the third identification information represents the other port of the near-end machine, in a case where a value represented by the second identification information is larger than a value represented by the fourth identification information, determining the second port of the current remote machine as a slave port of the current remote machine, and determining the first port of the current remote machine as a master port of the current remote machine.

Optionally, the obtaining module 72 is further configured to: acquiring a signal received by the current remote terminal from a device connected with a slave port of the current remote terminal in the target loop; recovering a clock signal according to the signal received from the equipment connected with the slave port of the current remote terminal in the target loop; and determining the recovered clock signal as a reference clock of the current remote terminal.

Optionally, the first determining module 74 is further configured to: determining that a first remote terminal fails when a signal sent by a second remote terminal connected with a master port of a current remote terminal is received by the current remote terminal and a signal sent by the first remote terminal connected with a slave port of the current remote terminal is not received by the current remote terminal within a preset time period; switching the slave port of the current remote machine and the master port of the current remote machine, wherein the plurality of remote machines further include the first remote machine and the second remote machine.

According to another embodiment of the present invention, there is provided a reference clock determining apparatus including: a processing module for performing the following for each remote in a target loop, wherein each remote is determined to be a current remote when the following are performed for the each remote: acquiring a first signal received by a first port of the current remote-end machine from the target loop and a second signal received by a second port of the current remote-end machine from the target loop, wherein the target loop comprises: a loop consisting of a near-end unit and a plurality of far-end units; according to the first signal and the second signal, determining that one of the first port and the second port of the current remote machine is a slave port and the other one of the first port and the second port is a master port; and determining the reference clock of the current remote machine according to the signal received by the slave port of the current remote machine from the target loop.

Another embodiment of the present invention further provides a system for determining a reference clock, including: a near-end machine and a plurality of remote machines, wherein each of the plurality of remote machines is configured to perform the following operations, wherein each of the plurality of remote machines determines itself as a current remote machine when performing the following operations:

acquiring a first signal received by a first port of the current remote-end machine from the target loop and a second signal received by a second port of the current remote-end machine from the target loop, wherein the target loop comprises: a loop consisting of the near-end machine and the plurality of far-end machines;

according to the first signal and the second signal, determining that one of the first port and the second port of the current remote machine is a slave port and the other one of the first port and the second port is a master port;

and determining the reference clock of the current remote machine according to the signal received by the slave port of the current remote machine from the target loop.

Optionally, the near-end machine is configured to: respectively sending a first signal and a second signal to the target loop through a first port of the near-end machine and a second port of the near-end machine, where the first signal is transmitted in the target loop according to a first signal transmission path, the second signal is transmitted in the target loop according to a second signal transmission path, the first signal sent by the near-end machine carries first identification information and second identification information, the first identification information is used to represent the first port of the near-end machine, the second identification information is used to represent that the number of far-end machines through which the first signal passes in the target loop is an initial value, the second signal sent by the near-end machine carries third identification information and fourth identification information, the third identification information is used to represent the second port of the near-end machine, and the fourth identification information is used to represent the number of far-end machines through which the second signal passes in the target loop The number is the initial value.

Optionally, the present remote unit is further configured to: receiving the first signal from a first device connected to the current remote machine through a first port of the current remote machine and receiving the second signal from a second device connected to the current remote machine through a second port of the current remote machine, wherein the first device is a device in the target loop connected to the first port of the current remote machine and the second device is a device in the target loop connected to the second port of the current remote machine; after a value represented by second identification information carried in the first signal received by the current remote terminal is increased by a preset value, updated second identification information is obtained, and after a value represented by fourth identification information carried in the second signal received by the second port of the current remote terminal is increased by the preset value, updated fourth identification information is obtained; updating second identification information in the first signal received by the current remote terminal by using the updated second identification information to obtain an updated first signal, and sending the updated first signal to the second device through a second port of the current remote terminal; and updating fourth identification information in the second signal received by the current remote terminal by using the updated fourth identification information to obtain an updated second signal, and sending the updated second signal to the first device through the first port of the current remote terminal.

Optionally, the present remote unit is further configured to: acquiring first identification information and second identification information carried in the first signal, and third identification information and fourth identification information carried in the second signal, wherein the second identification information is used for indicating the number of remote terminals passed by the first signal in the target loop, and the fourth identification information is used for indicating the number of remote terminals passed by the second signal in the target loop; in a case where the first identification information represents one port of the near-end machine and the third identification information represents another port of the near-end machine, in a case where a value represented by the second identification information is less than or equal to a value represented by the fourth identification information, determining the first port of the current far-end machine as a slave port of the current far-end machine and determining the second port of the current far-end machine as a master port of the current far-end machine; in a case where the first identification information represents the one port of the near-end machine and the third identification information represents the other port of the near-end machine, in a case where a value represented by the second identification information is larger than a value represented by the fourth identification information, determining the second port of the current remote machine as a slave port of the current remote machine, and determining the first port of the current remote machine as a master port of the current remote machine.

Optionally, the present remote unit is further configured to: acquiring a signal received by the current remote terminal from a device connected with a slave port of the current remote terminal in the target loop; recovering a clock signal according to the signal received from the equipment connected with the slave port of the current remote terminal in the target loop; and determining the recovered clock signal as a reference clock of the current remote terminal.

Optionally, the present remote unit is further configured to: determining that a first remote terminal fails when a signal sent by a second remote terminal connected with a master port of a current remote terminal is received by the current remote terminal and a signal sent by the first remote terminal connected with a slave port of the current remote terminal is not received by the current remote terminal within a preset time period; switching the slave port of the current remote machine and the master port of the current remote machine, wherein the plurality of remote machines further include the first remote machine and the second remote machine.

An embodiment of the present invention further provides a storage medium including a stored program, wherein the program executes any one of the methods described above.

Alternatively, in the present embodiment, the storage medium may be configured to store program codes for performing the following steps:

s1, for each remote machine in the target loop, determining said each remote machine as the current remote machine when:

acquiring a first signal received by a first port of the current remote-end machine from the target loop and a second signal received by a second port of the current remote-end machine from the target loop, wherein the target loop comprises: a loop consisting of a near-end unit and a plurality of far-end units;

Optionally, in this embodiment, the storage medium may include, but is not limited to: various media capable of storing program codes, such as a usb disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a removable hard disk, a magnetic disk, or an optical disk.

Optionally, the specific examples in this embodiment may refer to the examples described in the above embodiments and optional implementation manners, and this embodiment is not described herein again.

Embodiments of the present invention also provide an electronic device comprising a memory having a computer program stored therein and a processor arranged to run the computer program to perform the steps of any of the above method embodiments.

Optionally, the electronic apparatus may further include a transmission device and an input/output device, wherein the transmission device is connected to the processor, and the input/output device is connected to the processor.

Optionally, in this embodiment, the processor may be configured to execute the following steps by a computer program:

Fig. 7 is a schematic structural diagram of an alternative electronic device according to an embodiment of the invention. Alternatively, it can be understood by those skilled in the art that the structure shown in fig. 7 is only an illustration, and the electronic device may also be a terminal device such as a smart phone (e.g., an Android phone, an iOS phone, etc.), a tablet computer, a palm computer, a Mobile Internet Device (MID), a PAD, and the like. Fig. 7 is a diagram illustrating a structure of the electronic device. For example, the electronic device may also include more or fewer components (e.g., network interfaces, etc.) than shown in FIG. 7, or have a different configuration than shown in FIG. 7.

The memory 1002 may be used to store software programs and modules, such as program instructions/modules corresponding to the method for determining a reference clock and the device for determining a reference clock in the embodiment of the present invention, and the processor 1004 executes various functional applications and data processing by running the software programs and modules stored in the memory 1002, that is, implements the method for determining a reference clock. The memory 1002 may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some examples, the memory 1002 may further include memory located remotely from the processor 1004, which may be connected to the terminal over a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof. As an example, the memory 1002 may include, but is not limited to, the obtaining module 72, the first determining module 74, and the second determining module 76 of the determining device of the reference clock. In addition, other module units in the above-mentioned device for determining the reference clock may also be included, but are not limited to this, and are not described in detail in this example.

Optionally, the above-mentioned transmission device 1006 is used for receiving or sending data via a network. Examples of the network may include a wired network and a wireless network. In one example, the transmission device 1006 includes a Network adapter (NIC) that can be connected to a router via a Network cable and other Network devices so as to communicate with the internet or a local area Network. In one example, the transmission device 1006 is a Radio Frequency (RF) module, which is used for communicating with the internet in a wireless manner.

In addition, the electronic device further includes: a display 1008 for displaying a screen; and a connection bus 1010 for connecting the respective module parts in the above-described electronic apparatus.

In other embodiments, the terminal or the server may be a node in a distributed system, wherein the distributed system may be a blockchain system, and the blockchain system may be a distributed system formed by connecting a plurality of nodes through a network communication form. Nodes can form a Peer-To-Peer (P2P, Peer To Peer) network, and any type of computing device, such as a server, a terminal, and other electronic devices, can become a node in the blockchain system by joining the Peer-To-Peer network.

It will be apparent to those skilled in the art that the modules or steps of the present invention described above may be implemented by a general purpose computing device, they may be centralized on a single computing device or distributed across a network of multiple computing devices, and alternatively, they may be implemented by program code executable by a computing device, such that they may be stored in a storage device and executed by a computing device, and in some cases, the steps shown or described may be performed in an order different than that described herein, or they may be separately fabricated into individual integrated circuit modules, or multiple ones of them may be fabricated into a single integrated circuit module. Thus, the present invention is not limited to any specific combination of hardware and software.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining a reference clock, comprising:

performing the following for each remote machine in the target loop, wherein each remote machine is determined to be the current remote machine when the following are performed for that remote machine:

determining a reference clock of the current remote machine according to a signal received by a slave port of the current remote machine from the target loop;

wherein the determining that one of the first port and the second port of the current remote machine is a slave port and the other of the first port and the second port is a master port according to the first signal and the second signal comprises: determining that a first remote terminal fails when a signal sent by a second remote terminal connected with a master port of a current remote terminal is received by the current remote terminal and a signal sent by the first remote terminal connected with a slave port of the current remote terminal is not received by the current remote terminal within a preset time period; switching the slave port of the current remote machine and the master port of the current remote machine, wherein the plurality of remote machines further include the first remote machine and the second remote machine;

wherein the method further comprises: maintaining a master port and a slave port of a third remote unit unchanged, wherein the master port of the third remote unit is connected to the first remote unit, and the plurality of remote units includes the third remote unit; sending a fourth signal to the target loop through a slave port of the third remote terminal, where the fourth signal carries seventh identification information and eighth identification information, the seventh identification information is used to indicate that the target loop has a fault, and the eighth identification information is used to indicate an initial value; under the condition that each remote machine in a second remote machine set in the plurality of remote machines receives the fourth signal, determining that the target loop has a fault according to seventh identification information carried in the fourth signal, keeping a master port and a slave port of the remote machine unchanged, and sending the fourth signal to a fourth device connected with a slave port of the remote machine through the slave port of the remote machine, wherein the fourth device is a next remote machine or a near-end machine connected with the slave port of the remote machine;

wherein the determining that one of the first port and the second port of the current remote machine is a slave port and the other of the first port and the second port is a master port according to the first signal and the second signal comprises: acquiring first identification information and second identification information carried in the first signal, and third identification information and fourth identification information carried in the second signal, wherein the second identification information is used for indicating the number of remote terminals passed by the first signal in the target loop, and the fourth identification information is used for indicating the number of remote terminals passed by the second signal in the target loop; in a case where the first identification information represents one port of the near-end machine and the third identification information represents another port of the near-end machine, in a case where a value represented by the second identification information is less than or equal to a value represented by the fourth identification information, determining the first port of the current far-end machine as a slave port of the current far-end machine and determining the second port of the current far-end machine as a master port of the current far-end machine; in a case where the first identification information represents the one port of the near-end machine and the third identification information represents the other port of the near-end machine, in a case where a value represented by the second identification information is larger than a value represented by the fourth identification information, determining the second port of the current remote machine as a slave port of the current remote machine, and determining the first port of the current remote machine as a master port of the current remote machine.

2. The method of claim 1, wherein prior to said performing for each remote machine in the target loop:

respectively sending a first signal and a second signal to the target loop through a first port of the near-end machine and a second port of the near-end machine, where the first signal is transmitted in the target loop according to a first signal transmission path, the second signal is transmitted in the target loop according to a second signal transmission path, the first signal sent by the near-end machine carries first identification information and second identification information, the first identification information is used to represent the first port of the near-end machine, the second identification information is used to represent that the number of far-end machines through which the first signal passes in the target loop is an initial value, the second signal sent by the near-end machine carries third identification information and fourth identification information, the third identification information is used to represent the second port of the near-end machine, and the fourth identification information is used to represent the number of far-end machines through which the second signal passes in the target loop The number is the initial value.

3. The method of claim 2, wherein after said obtaining a first signal received by a first port of said current remote unit from said target loop and a second signal received by a second port of said current remote unit from said target loop, said method further comprises:

receiving the first signal from a first device connected to the current remote machine through a first port of the current remote machine and receiving the second signal from a second device connected to the current remote machine through a second port of the current remote machine, wherein the first device is a device in the target loop connected to the first port of the current remote machine and the second device is a device in the target loop connected to the second port of the current remote machine;

after a value represented by second identification information carried in the first signal received by the current remote terminal is increased by a preset value, updated second identification information is obtained, and after a value represented by fourth identification information carried in the second signal received by the second port of the current remote terminal is increased by the preset value, updated fourth identification information is obtained;

updating second identification information in the first signal received by the current remote terminal by using the updated second identification information to obtain an updated first signal, and sending the updated first signal to the second device through a second port of the current remote terminal;

and updating fourth identification information in the second signal received by the current remote terminal by using the updated fourth identification information to obtain an updated second signal, and sending the updated second signal to the first device through the first port of the current remote terminal.

4. The method of claim 1, wherein said determining a reference clock of said current remote unit from signals received from said target loop at a slave port of said current remote unit comprises:

acquiring a signal received by the current remote terminal from a device connected with a slave port of the current remote terminal in the target loop;

recovering a clock signal according to the signal received from the equipment connected with the slave port of the current remote terminal in the target loop;

and determining the recovered clock signal as a reference clock of the current remote terminal.

5. An apparatus for determining a reference clock, comprising: an obtaining module, a first determining module and a second determining module, wherein the device is configured to determine, by the obtaining module, the first determining module and the second determining module, a reference clock of each remote unit in a target loop, wherein when the reference clock of each remote unit is determined, each remote unit is determined as a current remote unit:

wherein the obtaining module is configured to obtain a first signal received by a first port of the current remote end from the target loop, and a second signal received by a second port of the current remote end from the target loop, where the target loop includes: a loop consisting of a near-end unit and a plurality of far-end units;

the first determining module is configured to determine, according to the first signal and the second signal, that one of the first port and the second port of the current remote machine is a slave port, and the other of the first port and the second port is a master port;

the second determining module is configured to determine a reference clock of the current remote terminal according to a signal received from the target loop by a slave port of the current remote terminal;

the second determining module is further configured to: determining that a first remote terminal fails when a signal sent by a second remote terminal connected with a master port of a current remote terminal is received by the current remote terminal and a signal sent by the first remote terminal connected with a slave port of the current remote terminal is not received by the current remote terminal within a preset time period; switching the slave port of the current remote machine and the master port of the current remote machine, wherein the plurality of remote machines further include the first remote machine and the second remote machine; sending a third signal to the target loop through a current slave port of the current remote terminal, wherein the third signal carries fifth identification information and sixth identification information, the fifth identification information is used for indicating that the target loop is in fault, and a value indicated by the sixth identification information is used for indicating an initial value;

wherein the apparatus is further configured to: maintaining a master port and a slave port of a third remote unit unchanged, wherein the master port of the third remote unit is connected to the first remote unit, and the plurality of remote units includes the third remote unit; sending a fourth signal to the target loop through a slave port of the third remote terminal, where the fourth signal carries seventh identification information and eighth identification information, the seventh identification information is used to indicate that the target loop has a fault, and the eighth identification information is used to indicate an initial value; under the condition that each remote machine in a second remote machine set in the plurality of remote machines receives the fourth signal, determining that the target loop has a fault according to seventh identification information carried in the fourth signal, keeping a master port and a slave port of the remote machine unchanged, and sending the fourth signal to a fourth device connected with a slave port of the remote machine through the slave port of the remote machine, wherein the fourth device is a next remote machine or a near-end machine connected with the slave port of the remote machine;

the obtaining module is further configured to: acquiring first identification information and second identification information carried in the first signal, and third identification information and fourth identification information carried in the second signal, wherein the second identification information is used for indicating the number of remote terminals passed by the first signal in the target loop, and the fourth identification information is used for indicating the number of remote terminals passed by the second signal in the target loop; the first determining module is further configured to: in a case where the first identification information represents one port of the near-end machine and the third identification information represents another port of the near-end machine, in a case where a value represented by the second identification information is less than or equal to a value represented by the fourth identification information, determining the first port of the current far-end machine as a slave port of the current far-end machine and determining the second port of the current far-end machine as a master port of the current far-end machine; in a case where the first identification information represents the one port of the near-end machine and the third identification information represents the other port of the near-end machine, in a case where a value represented by the second identification information is larger than a value represented by the fourth identification information, determining the second port of the current remote machine as a slave port of the current remote machine, and determining the first port of the current remote machine as a master port of the current remote machine.

6. A system for determining a reference clock, comprising: a near-end machine and a plurality of remote machines, wherein each of the plurality of remote machines is configured to perform the following operations, wherein each of the plurality of remote machines determines itself as a current remote machine when performing the following operations:

acquiring a first signal received by a first port of the current remote terminal from a target loop and a second signal received by a second port of the current remote terminal from the target loop, wherein the target loop comprises: a loop consisting of the near-end machine and the plurality of far-end machines;

the present remote machine is further configured to: determining that a first remote terminal fails when a signal sent by a second remote terminal connected with a master port of a current remote terminal is received by the current remote terminal and a signal sent by the first remote terminal connected with a slave port of the current remote terminal is not received by the current remote terminal within a preset time period; switching the slave port of the current remote machine and the master port of the current remote machine, wherein the plurality of remote machines further include the first remote machine and the second remote machine;

wherein the plurality of remote units further comprises a third remote unit, the third remote unit further configured to: keeping the master port and the slave port of the third remote machine unchanged, wherein the master port of the third remote machine is connected to the first remote machine; sending a fourth signal to the target loop through a slave port of the third remote terminal, where the fourth signal carries seventh identification information and eighth identification information, the seventh identification information is used to indicate that the target loop has a fault, and the eighth identification information is used to indicate an initial value; each remote machine of a second set of remote machines of the plurality of remote machines, upon receiving the fourth signal, to: determining that the target loop fails according to seventh identification information carried in the fourth signal, keeping a master port and a slave port of the target loop unchanged, and sending the fourth signal to fourth equipment connected with the slave port of the target loop through the slave port of the target loop, wherein the fourth equipment is a next far-end machine or a near-end machine connected with the slave port of the target loop;

7. A storage medium, in which a computer program is stored, wherein the computer program is arranged to, when executed by a processor, perform the method of any one of claims 1 to 4.

8. An electronic device comprising a memory and a processor, characterized in that the memory has stored therein a computer program, the processor being arranged to execute the method of any of claims 1 to 4 by means of the computer program.