CN109274517B

CN109274517B - GPS backup system and method

Info

Publication number: CN109274517B
Application number: CN201810813384.7A
Authority: CN
Inventors: 罗新军; 王楚锋; 罗京
Original assignee: China Information Consulting and Designing Institute Co Ltd
Current assignee: China Information Consulting and Designing Institute Co Ltd
Priority date: 2018-07-23
Filing date: 2018-07-23
Publication date: 2022-04-08
Anticipated expiration: 2038-07-23
Also published as: CN109274517A

Abstract

The invention discloses a GPS backup system and a method, comprising a main GPS receiving module, a backup switching unit, a GPS time service distribution unit, a network management center and the like, wherein the GPS receiving module is connected with the backup switching unit through a radio frequency cable, and the backup switching unit is connected with the GPS time service distribution unit through the radio frequency cable; the invention also discloses a GPS backup method, which comprises the following steps: (1) a backup system; (2) measuring the phase and frequency of a GPS clock source signal to identify the state of a GPS receiving module and the state of a receiving satellite; (3) selecting a GPS receiving module switching mode, and selecting a clock source signal of a main GPS receiving module or a standby GPS receiving module as a GPS output signal according to a measurement result and a pre-selected backup switching mode; (4) and reporting the switching state and switching alarm of the GPS module to a network management center.

Description

GPS backup system and method

Technical Field

The invention relates to the field of mobile communication, in particular to a GPS backup system and a method.

Background

With the continuous deepening of the LTE (Long Term Evolution) network construction and the formation of the LTE network scale, the network construction gradually enters the post-LTE era. The LTE wireless network has the characteristics of higher frequency band, macro-micro cooperation, heterogeneous network and the like, stations in the network are dense, inter-station cooperation is difficult, interference is large, spectrum efficiency is reduced, and station building cost is higher and higher, meanwhile, spectrum resources are increasingly tense, the difficulty in acquiring station sites, sky surfaces and transmission resources is increasingly increased, the network interference environment is increasingly complex, and network construction faces a plurality of new challenges. The C-RAN is a green and energy-saving wireless access network framework, is mainly placed in a centralized mode based on BBUs, has the characteristics of centralization, cooperation, cloud computing and the like, can effectively solve the problems and challenges of difficult station building, high station building cost, high energy consumption and the like in LTE network construction, and is an important mode for mobile network construction in the later LTE era in order to save network construction cost and accelerate construction progress, more and more LTE network construction is based on C-RAN deployment.

The 5G technology has the technical characteristics of low time delay and high reliability, the 5G network puts higher requirements on the time delay of a forward network, and the ultra-low time delay enables small-scale deployment to become the first choice of 5G C-RAN; the technical characteristics of the 5G technology, such as NFV (network function virtualization), multi-RAT (radio access technology) resource coordination, etc., 5G C-RAN deployment requirements are based on virtualization and cloud architectures. With the continuous development of 5G technology and the schedule of the construction thereof, the C-RAN construction of the LTE network needs to consider the characteristics of 5G C-RAN, and particularly, the small-scale deployment of the LTE C-RAN is more beneficial to 5G evolution.

The C-RAN is a network architecture based on BBU (Base Band Unit) centralization, Remote Radio Remote Unit (RRU) and BBU pool architecture networking with small-scale BBU centralization are adopted, and each BBU pool is only responsible for RRU in the area under the jurisdiction; compared with the traditional D-RAN (distributed radio access network) wireless network networking mode, the C-RAN network architecture has clear characteristics, (1) BBU centralization: BBUs are placed in a centralized mode, interference is reduced through an inter-station cooperation technology, capacity is improved, and spectrum efficiency is improved; (2) BBU collaboration: by introducing a real-time high-speed internal interconnection architecture, scheduling information, channel information and user data can be exchanged between different BBUs in the BBU pool quickly and efficiently, and cooperation across BBUs can be realized better.

The BBU centralization under the C-RAN architecture also brings GPS synchronization centralization, new requirements and challenges are provided for a GPS synchronization scheme, and the synchronization scheme under the traditional C-RAN construction mainly comprises a multi-GPS synchronization scheme, a GPS power division synchronization scheme, a 1588v2 synchronization scheme and the like. (1) The traditional multi-GPS synchronization scheme adopts one GPS antenna for each BBU, is consistent with the existing D-RAN GPS scheme, and has high reliability, and the defects of the traditional multi-GPS synchronization scheme are that the number of the needed GPS antennas is large, the required layout space is large, the interference is difficult to control, all stations cannot be shared, the construction cost is high, and the resource waste is serious.

(2) According to the traditional GPS antenna scheme, 1/2 feeder lines, two power branches, three power branches and four power branches are adopted, multiple BBUs can be connected, generally, single-stage 4-path branches are supported at most, but the scheme insertion loss is large, the problems that satellite signals are weak, a BBU satellite receiver is abnormal in locking a satellite, clock step-out warning and the like occur easily occur, and particularly warning frequency is prone to occurring in severe weather such as thunderstorm, snow and the like. The method is suitable for common ultra-small-scale BBU centralized scenes. (3) The 1588v2 synchronization scheme needs extra 1588 clock services, such as a remote-end-based GPS time service system, has high synchronization clock precision, needs all transmission network nodes (routers, switches and the like) of the existing network to support an IEEE 1588v2 protocol, and is difficult to implement.

Disclosure of Invention

The purpose of the invention is as follows: a plurality of challenges faced by the current synchronization scheme for C-RAN network construction restrict the development of C-RAN construction, a GPS backup system and a method are researched to realize the backup and seamless switching of GPS clock source signals, and the network reliability, interference control and construction cost under a C-RAN architecture can be greatly improved. The system and the method have the advantages of simplicity in implementation, convenience in use, low cost, high stability, strong anti-interference performance and the like, and effectively solve the problems of limited GPS (global positioning system) layout surface, limited interference and the like. The invention aims to overcome the defects of the existing LTE network C-RAN synchronization scheme, and provides a GPS (global Positioning system) backup system and a method, wherein the method is operated on the LTE network GPS backup system.

The system comprises a main GPS receiving module, a standby switching unit, a GPS time service distribution unit and a network management center, wherein the main GPS receiving module and the standby GPS receiving module are respectively connected with the standby switching unit through radio frequency cables, and the standby switching unit is connected with the GPS time service distribution unit through the radio frequency cables;

the main GPS receiving module and the standby GPS receiving module respectively comprise mushroom heads, lightning arresters and feeder lines;

the backup switching unit comprises a switching logic unit and a control unit, wherein the control unit is used for detecting the phase and the frequency of a GPS clock source signal and controlling the switching logic unit to select the clock source signal of the main GPS receiving module or the standby GPS receiving module as the GPS clock source signal to be output according to the detection result;

the GPS time service distribution unit comprises a signal amplification unit, a signal distribution unit and a signal output unit, wherein the signal amplification unit is used for amplifying and filtering GPS clock source signals, the signal distribution unit is used for carrying out power average distribution on the amplified GPS clock source signals according to the number of output ports, and the signal output unit is responsible for outputting the GPS clock source signals subjected to power distribution at each GPS clock source signal output port of the GPS time service distribution unit;

the network management center is used for carrying out remote parameter query, parameter setting operation and equipment management on equipment, and comprises a main GPS receiving module, a standby GPS receiving module and a standby switching unit, wherein the main GPS receiving module, the standby GPS receiving module and the standby switching unit are used for carrying out remote query on working states and alarm states of the main GPS receiving module, the standby GPS receiving module and the standby switching unit. The system parameters of the equipment are set mainly as follows: setting an abnormal time length threshold value, a backup switching mode and the like of a GPS receiving module;

the field operation maintenance terminal is used for carrying out local parameter query and parameter setting operation on the equipment field and issuing a main/standby GPS clock source signal switching instruction to the equipment, is connected with equipment such as a backup switching unit and the like on the field through an Ethernet or a USB or an RS232/RS485 serial port, can carry out local manual switching on a GPS clock source by field control of the backup switching unit besides finishing the functions of parameter query and parameter setting which are the same as those of a network management center, and switches a clock source signal of a standby GPS receiving module to be used as a GPS clock source signal output of the backup switching unit.

The number of the GPS time service distribution units is n, and n is more than or equal to 1;

a GPS time service distribution unit connected with the backup switching unit through a radio frequency cable is a first stage;

the ith GPS time service distribution unit is connected with the output port of the first-stage GPS time service distribution unit through a radio frequency cable, and n is more than 1 and less than or equal to n.

The invention also provides a GPS backup method, which comprises the following steps:

step 1, backing up a system: setting a main GPS receiving module and a standby GPS receiving module; connecting the main GPS receiving module and the standby GPS receiving module to a backup switching unit through radio frequency cables respectively;

and 2, respectively measuring the phase and frequency of the GPS clock source signal of the main GPS receiving module and the GPS clock source signal of the standby GPS receiving module by the backup switching unit, and identifying the states of the main GPS receiving module and the standby GPS receiving module and the states of the main GPS receiving module and the standby GPS receiving module for receiving the satellite. When the backup switching unit detects that the frequency and the phase of the received GPS clock source signal are normal (for example, the frequency is 1575.42MHz and the error range thereof), the backup switching unit judges that the GPS receiving module is normal and can correctly receive the satellite, otherwise, the backup switching unit judges that the GPS receiving module has a fault or cannot correctly receive the satellite.

Step 3, initializing parameters such as an abnormal duration threshold, a GPS clock source signal clock source backup switching mode and the like; the parameters are remotely set by a network management center or locally set by an operation maintenance terminal and stored in a local nonvolatile register of the backup switching unit.

And 4, selecting the GPS clock source signal of the main GPS receiving module or the standby GPS receiving module as the GPS clock source signal to be output by the backup switching unit according to the preselected backup switching mode and the phase and frequency measurement result.

The backup switching mode in step 3 includes an automatic mode, and step 4 includes the following steps:

step 4-1, the backup switching unit selects the clock source signal of the main GPS receiving module as the GPS clock source signal by default and outputs the clock source signal;

step 4-2, the backup switching unit detects the phases and frequencies of the GPS clock source signals of the main GPS receiving module and the standby GPS receiving module connected with the backup switching unit, and identifies the satellite receiving states of the main GPS receiving module and the standby GPS receiving module; when the backup switching unit detects that the frequency and the phase of the received GPS clock source signal are normal (for example, the frequency is 1575.42MHz and the error range thereof), the backup switching unit judges that the GPS receiving module is normal and can correctly receive the satellite, otherwise, the backup switching unit judges that the GPS receiving module has a fault or cannot correctly receive the satellite.

4-3, if the receiving satellite states of the main GPS receiving module and the standby GPS receiving module are normal, resetting the corresponding time length timer for accumulating the abnormal receiving satellite states, and continuously detecting whether the receiving satellite states of the main GPS receiving module and the standby GPS receiving module are normal, if the receiving satellite states of the main GPS receiving module or the standby GPS receiving module are abnormal, executing the step 4-4;

4-4, starting a corresponding time length timer for accumulating abnormal receiving satellite states and starting to calculate time length;

step 4-5, if the accumulated abnormal satellite receiving state duration of the main GPS receiving module is smaller than a preset abnormal duration threshold, or the accumulated abnormal satellite receiving state duration of the standby GPS receiving module is smaller than a preset abnormal duration threshold, repeating the step 4-2 to the step 4-4;

step 4-6, if the accumulated time length of the abnormal receiving satellite state of the main GPS receiving module is greater than or equal to the preset abnormal time length threshold, judging that the main GPS receiving module has a fault or the abnormal receiving satellite state occurs, and reporting a main module fault alarm to a network management center; if the satellite receiving state of the standby GPS receiving module is normal, the standby switching unit starts switching, selects the clock source signal of the standby GPS receiving module as the GPS clock source signal to be output, and reports a switching alarm to the network management center;

and 4-7, if the abnormal accumulated time of the satellite receiving state of the standby GPS receiving module is greater than or equal to the preset abnormal time threshold, judging that the standby GPS receiving module has a fault, reporting a fault alarm of the standby module to a network management center, and repeating the steps 4-2-4.

The backup switching mode further includes a manual mode, and step 4 includes: an operator issues a switching instruction through a network management center or a field operation maintenance terminal, and the backup switching unit performs switching operation according to the received switching instruction: and switching the clock source signal of the standby GPS receiving module to be used as a GPS clock source signal for output.

When the main GPS receiving module or the standby GPS receiving module has a fault and the fault is repaired, the backup switching mode is reset to an automatic mode and a fault repair alarm is reported to the network management center.

The GPS backup system and the method realize the backup and seamless switching of the GPS clock source signal, have the advantages of simple realization, convenient use, low cost, high stability, strong anti-interference performance and the like, and solve the problems of limited GPS layout surface, limited interference and the like.

Has the advantages that:

compared with the prior art, the invention has the following advantages and effects:

(1) the GPS backup system and the method support the synchronization of the multi-BBU equipment under a single GPS antenna, the GPS resources of all stations are shared, the cost is low, and the construction is simple;

(2) the invention adopts a backup mode of a main/standby GPS receiving module, has high stability and reliability, and solves the problem that BBU concentration under a C-RAN architecture has high requirement on the reliability of GPS synchronous signals;

(3) the single GPS antenna adopted by the invention replaces the traditional multi-GPS antenna solution, and the engineering construction problems of limited surface of the field GPS antenna arrangement and mutual interference among GPS are solved;

(4) the invention is particularly suitable for scenes that GPS clock source signals have interference, sites with difficult site selection and the like need BBU centralized deployment, such as: hub building core machine room, airport, subway, large office, commercial district and other BBU centralized stations; the quantity of GPS time service distribution units can be considered according to the centralized quantity of the BBUs, one set of time service system can simultaneously support the access of more BBUs, particularly a shared scene is built by multiple operator machine rooms, one set of time service system can be arranged to solve the problem of synchronization of the multiple BBUs, fusion sharing is achieved, and resource utilization is maximized.

Drawings

The foregoing and other advantages of the invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.

Fig. 1 is a schematic structural diagram of a GPS backup system according to the present invention.

Fig. 2 is a flowchart illustrating a GPS backup method according to the present invention.

Detailed Description

The invention is further explained below with reference to the drawings and the embodiments.

The GPS backup system of the invention is shown in figure 1, and comprises a main GPS receiving module, a standby GPS receiving module, a backup switching unit, a GPS time service distribution unit and a network management center. The GPS receiving module is connected with the backup switching unit through a feeder line, and the backup switching unit is connected with the GPS time service distribution unit through a radio frequency cable.

The main GPS receiving module and the standby GPS receiving module have the same structure and mainly comprise mushroom heads, lightning arresters, feeder lines and the like, and are respectively connected with the standby switching unit through the feeder lines to transmit the time information and the state information of the satellite.

The backup switching unit comprises a switching logic unit and a control unit, wherein the control unit is used for detecting the phase and the frequency of the GPS satellite signal and controlling the switching logic unit to select a clock signal source of the main GPS receiving module or the standby GPS receiving module as the GPS satellite signal to be output to the GPS time service distribution unit according to the detection result; the backup switching unit is connected with the GPS time service distribution unit through a radio frequency cable.

The GPS time service distribution unit comprises a signal amplification unit, a signal distribution unit, a signal output unit and the like and is used for amplifying, filtering, distributing power and outputting an input GPS clock source signal. The signal output unit is used for outputting the power-divided GPS clock source signal to a corresponding port; the output port of the GPS time service distribution unit is connected with the BBU through a radio frequency cable, and meanwhile, the GPS clock source signal output port of the first stage GPS time service distribution unit can also be connected with the next stage GPS time service distribution unit through a radio frequency cable and is used for expanding the GPS clock source signal output port.

The network management center is used for carrying out remote parameter query, parameter setting operation and equipment management on equipment, is connected with the backup switching unit through a wired network such as a wireless network or a radio frequency cable and the like, realizes remote query and sets system parameters of the backup switching unit, and mainly comprises: setting an abnormal time length threshold value, a backup switching mode and the like of a GPS receiving module; the standby GPS clock source switching device is used for inquiring the working states and alarm states (including alarm or normal states) of the main GPS receiving module, the standby GPS receiving module and the standby switching unit, and comprises a GPS receiving module fault alarm, a GPS clock source signal switching alarm, a standby switching mode, a standby switching switch and the like.

The GPS backup method of the present invention, as shown in fig. 2, includes the following steps:

step 2, the backup switching unit respectively measures the phase and frequency of the GPS clock source signal of the main GPS receiving module and the GPS clock source signal of the standby GPS receiving module, and identifies the states of the main GPS receiving module and the standby GPS receiving module and the states of the main GPS receiving module and the standby GPS receiving module for receiving the satellite; when the backup switching unit detects that the frequency and the phase of the received GPS clock source signal are normal (for example, the frequency is 1575.42MHz and the error range thereof), the GPS receiving module is considered to be normal and can correctly receive the satellite, otherwise, the GPS receiving module is considered to be failed or cannot correctly receive the satellite.

Step 3, initializing time length threshold values for measuring the abnormal state of the receiving satellite of the GPS receiving module, parameters such as a backup switching mode of a GPS clock source signal clock source and the like; the parameters are remotely set by a network management center or locally set by an operation maintenance terminal and stored in a local nonvolatile register of the backup switching unit.

Step 4, the backup switching unit selects a GPS clock source signal of the main GPS receiving module or the standby GPS receiving module as a GPS output signal according to a preselected backup switching mode and phase and frequency measurement results;

the backup switching mode has two modes, namely an automatic mode and a manual mode. The automatic mode specifically comprises the following steps:

(4-1) the backup switching unit defaults to select the clock source signal of the main GPS receiving module as a GPS clock source signal to be output;

(4-2) the backup switching unit detects the phases and frequencies of the GPS clock source signals of the main GPS receiving module and the backup GPS receiving module connected with the backup switching unit, and identifies the receiving satellite states of the main GPS receiving module and the backup GPS receiving module; when the backup switching unit detects that the frequency and the phase of the received GPS clock source signal are normal (for example, the frequency is 1575.42MHz and the error range thereof), the GPS receiving module is considered to be normal and can correctly receive the satellite, otherwise, the GPS receiving module is considered to be failed or cannot correctly receive the satellite.

(4-3) if the receiving satellite states of the main GPS receiving module and the standby GPS receiving module are normal, resetting the corresponding time length timer for accumulating the abnormal receiving satellite states, and repeating the steps (4-2) - (4-3);

(4-4) if the backup switching unit identifies that the receiving satellite state of the main or standby GPS receiving module connected with the backup switching unit is abnormal, starting a corresponding time length timer for accumulating the abnormal receiving satellite state and starting to calculate time length;

(4-5) if the accumulated abnormal time length of the receiving satellite state of the main GPS receiving module is less than the preset abnormal time length threshold value; if the abnormal accumulated time length of the satellite receiving state of the standby GPS receiving module is less than the preset abnormal time length threshold, repeating the steps (4-2) - (4-4);

(4-6) if the accumulated abnormal satellite receiving state time length of the main GPS receiving module is greater than or equal to a preset abnormal time length threshold, determining that the main GPS receiving module has a fault or the abnormal satellite receiving state, and reporting a fault alarm of the main GPS receiving module to a network management center; if the satellite receiving state of the standby GPS receiving module is normal, the standby switching unit starts switching, selects the clock source signal of the standby GPS receiving module as the GPS clock source signal to be output, and reports a GPS clock source signal switching alarm to the network management center;

and (4-7) if the abnormal accumulated time of the satellite receiving state of the standby GPS receiving module is greater than or equal to the preset abnormal time threshold, determining that the standby GPS receiving module has a fault, and reporting a fault alarm of the standby module to a network management center. And (4) repeating the steps (4-2) to (4-4).

The manual mode specifically is: an operator issues a switching instruction through a network management center or a field operation maintenance terminal, and the backup switching unit performs switching operation according to the received switching instruction: and switching the clock source signal of the standby GPS receiving module to be used as a GPS clock source signal for output.

And step 5, when the GPS receiving module has a fault and the fault is repaired, resetting the backup switching mode to an automatic mode and reporting a fault repair alarm to the network management center. And starting an automatic mode step.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

The present invention provides a GPS backup system and method, and a plurality of methods and ways for implementing the technical solution, the above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention. All the components not specified in the present embodiment can be realized by the prior art.

Claims

1. A GPS backup system is characterized by comprising a main GPS receiving module, a standby GPS receiving module, a backup switching unit, a GPS time service distribution unit and a network management center, wherein the main GPS receiving module and the standby GPS receiving module are respectively connected with the backup switching unit through radio frequency cables, and the backup switching unit is connected with the GPS time service distribution unit through the radio frequency cables;

the network management center is used for carrying out remote parameter query, parameter setting operation and equipment management on equipment, and comprises a main GPS receiving module, a standby GPS receiving module and a backup switching unit, wherein the main GPS receiving module, the standby GPS receiving module and the backup switching unit are used for carrying out remote query on working states and alarm states of the main GPS receiving module, the standby GPS receiving module and the backup switching unit;

the ith GPS time service distribution unit is connected with an output port of the first-stage GPS time service distribution unit through a radio frequency cable, and i is more than 1 and less than or equal to n;

the system performs the following steps:

step 2, the backup switching unit respectively measures the phase and frequency of the GPS clock source signal of the main GPS receiving module and the GPS clock source signal of the standby GPS receiving module, and identifies the states of the main GPS receiving module and the standby GPS receiving module and the states of the main GPS receiving module and the standby GPS receiving module for receiving the satellite;

step 3, initializing an abnormal duration threshold and a backup switching mode of a GPS clock source signal clock source;

step 4, the backup switching unit selects the GPS clock source signal of the main GPS receiving module or the standby GPS receiving module as the GPS clock source signal to output according to the pre-selected backup switching mode and the phase and frequency measuring result;

step 4-2, the backup switching unit detects the phases and frequencies of the GPS clock source signals of the main GPS receiving module and the standby GPS receiving module connected with the backup switching unit, and identifies the satellite receiving states of the main GPS receiving module and the standby GPS receiving module;

4-7, if the abnormal accumulated time of the satellite receiving state of the standby GPS receiving module is greater than or equal to the preset abnormal time threshold, judging that the standby GPS receiving module has a fault, reporting a fault alarm of the standby module to a network management center, and repeating the steps 4-2-4;

the backup switching mode further includes a manual mode, and step 4 includes: an operator issues a switching instruction through a network management center or a field operation maintenance terminal, and the backup switching unit performs switching operation according to the received switching instruction: switching the clock source signal of the standby GPS receiving module to be used as a GPS clock source signal for output;