Micro base station of mobile telecommunication network and timing method thereof

Abstract

The invention discloses a miniature base station of a mobile telecommunication network and a timing method thereof. The miniature base station comprises a receiving end, a main chip and a phase-locked loop, a receiving end receives a PTP packet, wherein the PTP packet has a synchronous Ethernet signal and a front-end timestamp; the main chip is connected to the receiving end, the main chip is provided with a time correction program, a PTP driving program and a synchronous register, and the PTP driving program reads a front-end timestamp; the phase-locked loop generates multiple frequency according to the reference frequency and sends the multiple frequency to the synchronous register; the PTP drive program refers to the multiple frequency of the synchronous register, generates a first local end timestamp and transmits the first local end timestamp to the time correction program, the time correction program generates time offset according to the first local end timestamp and the front end timestamp and sends the time offset to the PTP drive program, the PTP drive program corrects the synchronous register according to the time offset, and the synchronous register is started according to the time offset. And the PTP driving program outputs the second local end timestamp.

Description

Technical Field

[0001] The invention relates to a digital device and a time calibration method thereof, and in particular to a micro base station of a mobile telecommunication network and a time calibration method thereof. Background Art

[0002] With the rapid development of communication technology, users can communicate through wireless networks and connect to the Internet through mobile telephony. The current mobile communication protocol has developed to the fifth generation, commonly known as 5G communication technology (5th generation mobile networks or 5th generation wireless systems).

[0003] Under 5G communication technology, time synchronization between any two base stations or between base stations and terminals is more stringent. When time synchronization between any two devices is abnormal, the communication between the two devices will be interfered, which will affect the user experience of telecommunications or communications. In particular, 5G micro base stations (such as small cells) deployed indoors cannot use the Global Positioning System due to the shielding of buildings, making it impossible for 5G micro base stations to perform time synchronization.

[0004] In addition, although 5G micro base stations can use their own clock generators as a timing reference source, micro base stations often use low-precision clock generators, so they will experience clock skew after a long time. For communication equipment behind the micro base station, signal interference and other problems will occur during the communication process. For a micro base station at the end of a communication line, as long as any of the base stations in front have a timing error, it will affect the communication of the micro base station. Summary of the invention

[0005] In view of this, in one embodiment, the micro base station of the mobile telecommunication network includes a receiving end, a main chip and a phase-locked loop; the receiving end receives a PTP packet, the PTP packet has a synchronous Ethernet signal and a front-end timestamp; the main chip is connected to the receiving end, the main chip has a time correction program, a PTP driver and a synchronization register, the PTP driver reads the front-end timestamp of the PTP packet; the phase-locked loop is connected to the receiving end and the main chip, the phase-locked loop generates a multiple frequency according to the reference frequency of the synchronous Ethernet signal, and the phase-locked loop sends the multiple frequency to the synchronization register; wherein, the PTP driver refers to the multiple frequency of the synchronization register to generate a first local end timestamp, the PTP driver provides the first local end timestamp to the time correction program, the time correction program generates a time offset according to the first local end timestamp and the front-end timestamp and sends the time offset to the PTP driver, the PTP driver corrects the synchronization register according to the time offset, and the PTP driver outputs a second local end timestamp.

[0006] The local time stamp generates a calibrated second pulse signal, and the phase-locked loop outputs the calibrated second pulse signal to the modulation element.

[0007] In one embodiment, the main chip further includes a storage unit, the storage unit stores a record information file, and the time correction program records each generated time offset into the record information file.

[0008] In one embodiment, the master chip further includes a synchronization program, and the synchronization program determines whether the operation state of the master chip is a normal state, a delayed state, or an out-of-sync state according to the record information file.

[0009] In one embodiment, the main chip is in a delayed state, the PTP driver generates an average offset according to the time offset, and the time correction program corrects the synchronization register with the average offset to output a third local time stamp.

[0010] In one embodiment, the main chip is in a desynchronized state, and the PTP driver outputs a local second pulse signal to the phase-locked loop. The phase-locked loop corrects the synchronization register with the local second pulse signal to output a fourth local end timestamp.

[0011] In one embodiment, the main chip further includes a monitoring program. The monitoring program detects that the PTP driver stops updating the time offset. The monitoring program provides a preset offset to the PTP driver so that the PTP driver calibrates the synchronization register according to the preset offset.

[0012] In one embodiment, a time synchronization method for a mobile telecommunication network includes the following steps: a micro base station receives a PTP packet, the PTP packet includes a synchronous Ethernet signal and a front-end timestamp; the micro base station generates a multiple frequency according to the synchronous Ethernet signal; the micro base station reads the front-end timestamp of the PTP packet; the micro base station references the multiple frequency to obtain a first local end timestamp for timing; the micro base station generates a time offset according to the front-end timestamp and the first local end timestamp; the micro base station generates a second local end timestamp according to the time offset.

[0013] In one embodiment, the step of receiving the timing request by the femto base station includes the femto base station being connected to a time reference terminal; and the time reference terminal transmitting the timing request to the femto base station.

[0014] In one embodiment, the step of referring to the multiple frequency in the micro base station further includes a clock generator of the micro base station providing a preset operating frequency; the micro base station replaces the preset operating frequency with the multiple frequency and obtains a second local time stamp.

[0015] In one embodiment, the step of "generating a time offset based on a front-end timestamp and a first local end timestamp" in the micro base station includes the micro base station recording each time offset to a record information file; the micro base station determines whether the operation status is a normal state, a delayed state or an out-of-sync state based on the record information file.

[0016] In one embodiment, the operation state is a delayed state and further includes the femtocell generating an average offset according to the time offset; the femtocell outputs a third local time stamp with reference to the average offset.

[0017] In one embodiment, the operation state is an out-of-sync state and further includes the femtocell outputting a fourth local time stamp according to the local pulse second signal.

[0018] The micro base station and the timing processing method are applied to the timing processing of the mobile communication network. The micro base station generates a higher-precision first local end timestamp through the PTP packet and the synchronous Ethernet signal. Therefore, the micro base station compares the first local end timestamp with the front-end timestamp and obtains the corresponding time offset. The micro base station further uses the time offset to generate a second local end timestamp. The micro base station performs modulation and demodulation (Modulation & Demodulation) of the communication according to the second local end timestamp. The micro base station can be based on the timing reference of the external network. Therefore, the micro base station does not need to set up an additional higher-precision clock generator. In addition to reducing production costs, the micro base station can also use the recorded time offset as the source of timing when the time reference end is lost, so as to maintain a longer frequency synchronization time and reduce interference between signals.

[0019] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments, but is not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A diagram of the architecture of a time synchronization system for mobile telecommunication network communications according to an embodiment of the present invention.

[0021] Figure 2 FIG. 1 is a schematic diagram of components of a micro base station of a mobile telecommunication network according to an embodiment of the present invention.

[0022] Figure 3 FIG. 4 is a flow chart of a method for synchronizing time in a mobile telecommunication network according to an embodiment of the present invention.

[0023] Figure 4 A schematic diagram of generating a first local timestamp according to an embodiment.

[0024] Figure 5 A schematic diagram of generating a second local timestamp according to an embodiment.

[0025] Figure 6 FIG. 1 is a schematic diagram of components of a micro base station of a mobile telecommunication network according to another embodiment.

[0026] Figure 7 FIG. 4 is a schematic diagram of a main chip operation state flow chart of an embodiment.

[0027] Among them, the reference numerals

[0028] 1000: Time calibration system

[0029] 100: Time reference terminal

[0030] 200: Intermediary base station set

[0031] 210: Communication base station

[0032] 300: Micro base station

[0033] 310: Receiving end

[0034] 320: Main chip

[0035] 321:PTP Driver

[0036] 322: Time Correction Procedure

[0037] 323: Synchronous register

[0038] 324:Clock Generator

[0039] 330: Phase-locked loop

[0040] 340: Modulation element

[0041] 350: Storage element

[0042] 351: Record data file

[0043] 360: Monitoring Program

[0044] 370: Synchronization Program

[0045] 410:PTP packet

[0046] 411:Synchronous Ethernet signal

[0047] 412: front-end timestamp

[0048] 421: Default operating frequency

[0049] 422: Multiple frequency

[0050] 423: Time offset

[0051] 431: First local time stamp

[0052] 432: Second local time stamp

[0053] 441: Corrected pulse-per-second signal

[0054] S310,S320,S330,S340,S350,S360,S710,S720,S730,S740,S750: Steps DETAILED DESCRIPTION

[0055] The structural principle and working principle of the present invention are described in detail below in conjunction with the accompanying drawings:

[0056] Please refer to Figure 1 and Figure 2 The timing system for mobile telecommunication network communication (hereinafter referred to as timing system 1000) includes a time reference terminal 100 (grandmaster), an intermediate base station set 200 and a micro base station 300 (small cell).

[0057] The time reference end 100 regularly broadcasts a PTP packet 410 (Precision Time Protocol, PTP) to the micro base station 300. The time reference end 100 can be an independent network time master clock, or one of the communication base stations 210 of the intermediate base station set 200, so that the selected communication base station 210 serves as the time reference end 100. Figure 1 An independent time reference end 100 is used as an illustration, but in actual practice, any communication base station 210 with a network clock can be selected from the intermediate base station set 200 as the time reference end 100 .

[0058] The intermediate base station set 200 is connected to the time reference end 100 and the micro base station 300. The intermediate base station set 200 can be composed of multiple communication base stations 210, or a single communication base station 210. The communication base station 210 is a macro base station (Macrocell Base Stations), a micro base station (Microcell Base Stations), a picocell base station (Picocell Base Stations), a nano base station (Femtocell Base Stations) or a combination thereof. Figure 1 In the example, a plurality of communication base stations 210 constitute an intermediate base station set 200. The communication base stations 210 may be connected to each other via a physical Ethernet network or a telecommunication backbone network, or the communication base stations 210 may be connected to a micro base station 300.

[0059] The micro base station 300 has a receiving end 310 (phy), a main chip 320, a phase-locked loop 330 and a modulation element 340. Figure 2 As shown. The receiving end 310 is connected to the time reference end 100. The receiving end 310 receives the PTP packet 410 of the time reference end 100, and the PTP packet 410 has a synchronous Ethernet signal 411 and a front-end timestamp 412 (timestamp). The main chip 320 is connected between the receiving end 310 and the phase-locked loop 330. The phase-locked loop 330 is connected to the modulation element 340. The phase-locked loop 330 is used to provide a reference frequency to the main chip 320, so that the main chip 320 generates a multiple frequency 422 and outputs the corresponding result to the modulation element 340, and its intermediate operation will be described later.

[0060] The main chip 320 includes a clock generator 324, a synchronization register 323, a time calibration program 322 (ptp41), and a PTP driver 321 (Precision Time Protocol Driver, PTP driver). Figure 2 In order to facilitate the description of the overall operation of the main chip 320, the application program (userspace, not shown) and the kernel program (kernel space, not shown) are drawn at the same time. Figure 2 The clock generator 324 is connected to the synchronous register 323 so that the synchronous register can output a corresponding timing cycle.

[0061] Before the initial time calibration, the clock generator 324 provides a preset operating frequency 421 to the synchronization register 323, so that the synchronization register 323 generates an uncorrected local time stamp according to the preset clock. The PTP driver 321 obtains the preset operating frequency 421 of the synchronization register 323. The PTP driver 321 generates a corresponding local time stamp according to the obtained preset operating frequency 421.

[0062] After the micro base station 300 is network-connected to the time reference end 100, the main chip 320 of the micro base station 300 executes the time calibration program 322 and the PTP driver 321. The time calibration program 322 is used to generate a time offset 423 for the PTP driver 321 and related components to calculate the corresponding local time stamp (no number). Please refer to Figure 3 , Figure 4 and Figure 5 The time synchronization method of the mobile telecommunication network of the micro base station 300 comprises the following steps:

[0063] Step S310: The micro base station receives a PTP packet, wherein the PTP packet includes a synchronous Ethernet signal and a front-end timestamp;

[0064] Step S320: the micro base station generates a multiple frequency according to the synchronous Ethernet signal;

[0065] Step S330: the micro base station reads the front-end timestamp of the PTP packet;

[0066] Step S340: The micro base station references the multiple frequency to obtain a first local time stamp;

[0067] Step S350: the femtocell generates a time offset according to the front-end timestamp and the first local timestamp; and

[0068] Step S360: The femtocell generates a second local timestamp according to the time offset.

[0069] First, the micro base station 300 is connected to the time reference end 100 via an Ethernet network or a telecommunications network. The time reference end 100 sends a timing request to the micro base station 300, so that the micro base station 300 starts the timing process (corresponding to step S310). The timing request includes a PTP packet 410, and the PTP packet 410 includes a synchronous Ethernet signal 411 (SyncE) and a front-end timestamp 412. The receiving end 310 of the micro base station 300 receives the timing request and forwards the timing request to the main chip 320 and the phase-locked loop 330. The PTP driver 321 of the main chip 320 reads the front-end timestamp 412 of the PTP packet 410, and the PTP driver 321 sends the front-end timestamp 412 to the time calibration program 322 (corresponding to step S330).

[0070] Next, the phase-locked loop 330 reads the synchronous Ethernet signal 411 of the PTP packet 410. The reference frequency in the synchronous Ethernet signal 411 is 25 MHz, or a multiple of the reference frequency. The phase-locked loop 330 generates a multiple frequency 422 based on the reference frequency of the synchronous Ethernet signal 411 and multiplies it by a specified multiple, and the specified multiple is a rational number greater than the number "1". For example, the reference frequency is 50 MHz. The phase-locked loop 330 can output a multiple frequency 422 of 125 MHz. The phase-locked loop 330 provides the multiple frequency 422 to the synchronous register 323 of the main chip 320 (corresponding to step S320).

[0071] The synchronization register 323 stops obtaining the preset operating frequency 421 from the clock generator 324. The synchronization register 323 replaces the preset operating frequency 421 with the multiple frequency 422 (i.e., reclocks the synchronization register 323). The PTP driver 321 obtains the multiple frequency 422 from the synchronization register 323. The PTP driver 321 generates a new local time stamp according to the multiple frequency 422, and the generated time stamp is referred to as the first local time stamp 431 (corresponding to step S340). Since the accuracy of the reference frequency is higher than the preset operating frequency 421, the accuracy of the multiple frequency 422 is higher than the preset operating frequency 421. Therefore, the accuracy of the first local time stamp 431 will also be higher than the local time stamp before correction. The PTP driver 321 sends the first local time stamp 431 to the time correction program 322.

[0072] After the time correction program 322 obtains the first local time stamp 431 and the front-end time stamp 412, the time correction program 322 calculates a time offset 423 according to the difference between the first local time stamp 431 and the front-end time stamp 412 (corresponding to step S350). The front-end time stamp 412 is the reference time provided by the time reference end 100. The first local time stamp 431 is the estimated time of the micro base station 300 corrected by the multiple frequency 422. The time correction program 322 sends the time offset 423 to the PTP driver 321. The PTP driver 321 adjusts the timing cycle output by the synchronization register 323 according to the time offset 423. Generally speaking, the cycle and the frequency are reciprocal to each other, so the cycle after the synchronization register 323 is adjusted will also change the frequency. The PTP driver 321 refers to the corrected synchronization register 323 and the multiple frequency 422 to output a new local time stamp, and this time stamp is called the second local time stamp 432 (corresponding to step S360).

[0073] The PLL 330 generates a calibrated pulse per second (PPS) signal 441 according to the sync register 323 and the second local time stamp 432. The PLL 330 outputs the calibrated pulse per second signal 441 to the modulation element 340 for the modulation element 340 to use as a time reference source for signal transmission.

[0074] After the micro base station 300 completes the second local time stamp 432, the synchronization register 323 uses the corrected multiple frequency 422 as the default operating frequency 421 for the next time synchronization request processing. The main chip 320 performs a new round of time synchronization processing according to the newly received PTP packet 410 and the default operating frequency 421 (i.e., the previous multiple frequency 422). Figure 3 Steps S320 to S360: Each time the femtocell 300 receives a new PTP packet 410, the femtocell 300 adjusts the accuracy of the local timestamp.

[0075] In some embodiments, the micro base station 300 further includes a storage element 350, please refer to Figure 6 The storage element 350 stores a log file 351. The time calibration program 322 records the time offset 423 generated each time into the log file 351. In other words, the micro base station 300 performs a time calibration process each time it receives a time calibration request, so the time calibration program 322 records the time offset 423 generated each time into the log file 351.

[0076] In some embodiments, the main chip 320 further includes a monitoring program 360 (monitor driver) and a synchronization program 370 (sync center). Figure 6 After the main chip 320 is enabled, it starts to execute the monitoring program 360 and the synchronization program 370. The monitoring program 360 detects whether the PTP driver 321 records the time offset 423 to the record information file. If the PTP driver 321 does not update the time offset 423 to the record information file, it means that the communication between the micro base station 300 and the time reference terminal 100 is interrupted.

[0077] The synchronization program 370 determines the operating state of the main chip 320 according to the recorded information file. The operating state is normal state, holdover state or freerun state. Please refer to Figure 7 When the PTP driver 321 still records the time offset 423 to the recording information file, it indicates that the operation status of the main chip 320 is normal.

[0078] If the PTP driver 321 stops updating, the operation state of the main chip 320 may be a delayed state or a desynchronized state. The micro base station 300 is not connected to the time reference terminal 100, and the monitoring program 360 determines whether the calibrated second pulse signal 441 output by the phase-locked loop 330 is stable. The stability of the calibrated second pulse signal 441 is based on the measurement error between the calibrated second pulse signal 441 and the second pulse signal of the time reference terminal 100. After a specified period of time, if the measurement error between the calibrated second pulse signal 441 and the second pulse signal of the time reference terminal 100 is greater than 1.5 microseconds (μs), it means that the micro base station 300 is unstable.

[0079] The monitoring program 360 provides the preset offset to the PTP driver 321, so that the PTP driver 321 calibrates the synchronization register 323 according to the preset offset. If the error of the calibrated second pulse signal 441 is maintained within a specified range, the monitoring program 360 determines that the phase-locked loop 330 is in a delayed state. Otherwise, the monitoring program 360 determines that the phase-locked loop 330 is in a lost state.

[0080] The monitoring program 360 obtains the number of time offsets 423 of the recording data file 351, and determines whether the number of time offsets 423 is greater than a threshold value. After the number of time offsets 423 exceeds the threshold value, the adjustment amount of the time offset 423 by the PTP driver 321 will converge. Therefore, the time correction program 322 can use the history data of the recording data file 351 as the basis for correcting the time.

[0081] The PTP driver 321 generates an average offset (i.e., the aforementioned preset offset) according to the time offset 423 of the recorded data file. The time correction program 322 corrects the multiple frequency 422 of the synchronization register 323 with the average offset to output a corrected second local time stamp 432, and this second local time stamp 432 is referred to as a third local time stamp (without a label).

[0082] If it is out of sync, the PTP driver 321 outputs a local second pulse signal to the phase-locked loop 330. The phase-locked loop 330 corrects the synchronization register 323 with the local second pulse signal (i.e., the preset offset) to output a second local end timestamp 432, which is referred to as the fourth local end timestamp (no number). The local second pulse signal can be the time offset 423 last recorded by the PTP driver 321, or the preset second pulse signal of the main chip 320.

[0083] The micro base station 300 and the timing processing method are applied to the timing processing of the mobile communication network. The micro base station 300 generates a higher precision first local end timestamp 431 through the PTP packet 410 and the synchronous Ethernet signal 411. Therefore, the micro base station 300 compares the first local end timestamp 431 with the front end timestamp 412 and obtains the corresponding time offset 423. The micro base station 300 further generates a second local end timestamp 432 using the time offset 423. The micro base station 300 performs communication modulation and demodulation processing according to the second local end timestamp 432. The micro base station 300 can be based on the timing reference of the external network. Therefore, the micro base station 300 does not need to set up an additional higher precision clock generator 324. In addition to reducing the production cost, the micro base station 300 can also use the recorded time offset 423 as the timing source when the time reference end 100 is lost, so as to maintain a longer frequency synchronization time and reduce interference between signals.

[0084] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A micro base station for a mobile telecommunication network, characterized in that: include: A receiving end receives a PTP packet having a synchronous Ethernet signal and a front-end timestamp; A main chip connected to the receiving end, the main chip having a time calibration program, a PTP driver and a synchronization register, the PTP driver reading the front-end timestamp of the PTP packet; and A phase-locked loop, connected to the receiving end and the main chip, the phase-locked loop generates a multiple frequency according to a reference frequency of the synchronous Ethernet signal, and the phase-locked loop sends the multiple frequency to the synchronous register; The PTP driver generates a first local-end timestamp by referring to the multiple frequency of the synchronization register. The PTP driver provides the first local-end timestamp to the time correction program. The time correction program generates a time offset according to the first local-end timestamp and the front-end timestamp and sends the time offset to the PTP driver. The PTP driver corrects the synchronization register according to the time offset. The PTP driver outputs a second local-end timestamp.

2. The micro base station of a mobile telecommunication network according to claim 1, characterized in that: The invention also comprises a modulation element connected to the phase-locked loop. The phase-locked loop generates a corrected second pulse signal according to the synchronous register and the second local end time stamp. The phase-locked loop outputs the corrected second pulse signal to the modulation element.

3. The micro base station of a mobile telecommunication network according to claim 1, characterized in that: The main chip also includes a storage unit, the storage unit stores a record information file, and the time correction program records the time offset generated each time into the record information file.

4. The micro base station of a mobile telecommunication network according to claim 3, characterized in that: The main chip also includes a synchronization program, and the synchronization program determines whether the operation state of the main chip is a normal state, a delayed state or a lost state according to the record information file.

5. The micro base station of a mobile telecommunication network according to claim 4, characterized in that: The main chip is in the postponement state, the PTP driver generates an average offset according to the time offsets, and the time correction program corrects the synchronization register with the average offset to output a third local end timestamp.

6. The micro base station of a mobile telecommunication network according to claim 4, characterized in that: The main chip is in the out-of-step state, the PTP driver outputs a local second pulse signal to the phase-locked loop, and the phase-locked loop corrects the synchronization register with the local second pulse signal to output a fourth local end timestamp.

7. The micro base station of a mobile telecommunication network as claimed in claim 3, characterized in that: The main chip also includes a monitoring program. The monitoring program detects that the PTP driver does not update the time offset. The monitoring program provides a preset offset to the PTP driver so that the PTP driver can calibrate the synchronization register according to the preset offset.

8. A time synchronization method for a mobile telecommunication network, characterized in that: The following steps are involved: A PTP packet is received by a micro base station, wherein the PTP packet includes a synchronous Ethernet signal and a front-end timestamp; The micro base station generates a multiple frequency according to the synchronous Ethernet signal; The micro base station reads the front-end timestamp of the PTP packet; The micro base station refers to the multiple frequency to obtain a first local time stamp for timing; The micro base station generates a time offset according to the front-end timestamp and the first local timestamp; as well as The micro base station generates a second local time stamp according to the time offset.

9. The time synchronization method for a mobile telecommunication network as claimed in claim 8, characterized in that: The step of “receiving the PTP packet by the micro base station” includes: The micro base station is connected to a time reference terminal; and The time reference terminal transmits the time calibration request to the micro base station.

10. The time synchronization method for a mobile telecommunication network as claimed in claim 8, characterized in that: The step of "the micro base station refers to the multiple frequency" also includes: A clock generator of the micro base station provides a preset operating frequency; and The micro base station replaces the preset operating frequency with the multiple frequency and obtains the second local time stamp.

11. The time synchronization method for a mobile telecommunication network as claimed in claim 8, characterized in that: The step of “the femtocell generates the time offset according to the front-end timestamp and the first local timestamp” includes: The micro base station records each of the time offsets in a record information file; and The micro base station determines an operation state as a normal state, a delayed state or an out-of-sync state according to the record information file.

12. The method for synchronizing time in a mobile telecommunication network as claimed in claim 11, characterized in that: The operational status for the deferred status also includes: The femtocell generates an average offset according to the time offsets; and The micro base station refers to the average offset and outputs a third local time stamp.

13. The time synchronization method for a mobile telecommunication network as claimed in claim 11, characterized in that: The operating state is the out-of-step state and also includes: The micro base station outputs a fourth local time stamp according to a local second pulse signal.

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