U.S. patent application number 17/506046 was filed with the patent office on 2022-02-10 for time synchronization method, apparatus, and system.
This patent application is currently assigned to HUAWEI TECHNOLOGIES CO., LTD.. The applicant listed for this patent is HUAWEI TECHNOLOGIES CO., LTD.. Invention is credited to Xingjian SHI, Jinhui WANG, Chuan XU.
Application Number | 20220045837 17/506046 |
Document ID | / |
Family ID | |
Filed Date | 2022-02-10 |
United States Patent
Application |
20220045837 |
Kind Code |
A1 |
SHI; Xingjian ; et
al. |
February 10, 2022 |
TIME SYNCHRONIZATION METHOD, APPARATUS, AND SYSTEM
Abstract
In various embodiments, a method is provided. In this method, a
first signal is received from a master node, and is sampled to
obtain a first sample. The first sample is then quantized to obtain
a quantized form of the first sample. A first synchronization
sequence is detected from the quantized form of the first sample at
T2. First information is received from the master node and the
first information is used to indicate a moment T1 at which the
master node sends the first synchronization sequence. A second
synchronization sequence is sent to the master node at T3. Second
information received from the master node and the second
information is used to indicate a moment T4 at which the master
node detects a quantized form of the second synchronization
sequence. Time synchronization is performed based on T1, T2, T3,
and T4.
Inventors: |
SHI; Xingjian; (Beijing,
CN) ; WANG; Jinhui; (Dongguan, CN) ; XU;
Chuan; (Shenzhen, CN) |
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Applicant: |
Name |
City |
State |
Country |
Type |
HUAWEI TECHNOLOGIES CO., LTD. |
Shenzhen |
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CN |
|
|
Assignee: |
HUAWEI TECHNOLOGIES CO.,
LTD.
Shenzhen
CN
|
Appl. No.: |
17/506046 |
Filed: |
October 20, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16914453 |
Jun 28, 2020 |
11171769 |
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17506046 |
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PCT/CN2017/120075 |
Dec 29, 2017 |
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16914453 |
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International
Class: |
H04L 7/00 20060101
H04L007/00; H04L 29/06 20060101 H04L029/06; H04Q 11/00 20060101
H04Q011/00 |
Claims
1. A time synchronization method, comprising: receiving, by a slave
node, a first signal from a master node, wherein the first signal
comprises a first synchronization sequence; detecting, by the slave
node, the first synchronization sequence from the first signal,
wherein a moment of detecting the first synchronization sequence is
T2; receiving, by the slave node, first information from the master
node, wherein the first information indicates a moment T1 at which
the master node sends the first synchronization sequence; sending,
by the slave node, a second synchronization sequence to the master
node, wherein a moment of sending the second synchronization
sequence is T3, and the second synchronization sequence is inserted
at the channel layer of the slave node; receiving, by the slave
node, second information from the master node, wherein the second
information indicates a moment T4 at which the master node detects
a quantized form of the second synchronization sequence; and
performing, by the slave node, time synchronization between the
slave node and the master node based on T1, T2, T3, and T4.
2. The method according to claim 1, wherein the detecting, by the
slave node, of the first synchronization sequence from the first
signal comprises: sampling, by the slave node, the first signal to
obtain a first sample; quantizing, by the slave node, the first
sample to obtain a quantized form of the first sample; and
detecting, by the slave node, the first synchronization sequence
from the quantized form of the first sample.
3. The method according to claim 2, wherein detecting, by the slave
node, of the first synchronization sequence from the quantized form
of the first sample comprises: performing, by the slave node,
correlation peak detection of the first synchronization sequence on
the quantized form of the first sample.
4. The method according to claim 2, wherein the first signal
further comprises a third synchronization sequence used for group
synchronization, and a first offset exists between a first element
of the third synchronization sequence and a first element of the
first synchronization sequence; and detecting, by the slave node,
of the first synchronization sequence from the quantized form of
the first sample comprises: determining, by the slave node, a first
location, wherein the first location is a location of the first
element of the third synchronization sequence in the quantized form
of the first sample; determining, by the slave node, a second
location based on the first location and the first offset, wherein
the second location is a location of the first element of the first
synchronization sequence in the quantized form of the first sample;
obtaining, by the slave node, a quantized form of a second sample
based on the second location, wherein the first sample comprises
the second sample; and detecting, by the slave node, the first
synchronization sequence from the quantized form of the second
sample.
5. The method according to claim 4, wherein the determining, by the
slave node, of the first location comprises: performing, by the
slave node, correlation peak detection of the third synchronization
sequence on the quantized form of the first sample to determine the
first location; and detecting, by the slave node, the first
synchronization sequence from the quantized form of the second
sample comprises: performing, by the slave node, correlation peak
detection of the first synchronization sequence on the quantized
form of the second sample.
6. The method according to claim 1, wherein the sending, by the
slave node, of the second synchronization sequence to the master
node comprises: generating, by the slave node, an encoded codeword;
inserting, by the slave node, the second synchronization sequence
into the encoded codeword; processing, by the slave node, the
encoded codeword into which the second synchronization sequence is
inserted, to generate a second signal; and sending, by the slave
node, the second signal to the master node.
7. The method according to claim 6, further comprising: inserting,
by the slave node into the encoded codeword, a fourth
synchronization sequence used for group synchronization, wherein a
second offset exists between a first element of the fourth
synchronization sequence and a first element of the second
synchronization sequence.
8. A time synchronization method, comprising: sending, by a master
node, a first signal to a slave node, wherein the first signal
comprises a first synchronization sequence, and the first
synchronization sequence is inserted at a channel layer of the
master node; sending, by the master node, first information to the
slave node, wherein the first information indicates a moment T1 at
which the master node sends the first synchronization sequence;
receiving, by the master node, a second signal from the slave node,
wherein the second signal comprises a second synchronization
sequence; detecting, by the master node, the second synchronization
sequence from the second signal, wherein a moment of detecting the
second synchronization sequence is T4; and sending, by the master
node, second information to the slave node, wherein the second
information indicates T4, and T1 and T4 are used for time
synchronization between the master node and the slave node.
9. The method according to claim 8, wherein the detecting, by the
master node, of the second synchronization sequence from the second
signal comprises: sampling, by the master node, the second signal
to obtain a third sample; quantizing, by the master node, the third
sample to obtain a quantized form of the third sample; and
detecting, by the master node, the second synchronization sequence
from the quantized form of the third sample.
10. The method according to claim 9, wherein detecting, by the
master node, of the second synchronization sequence from the
quantized form of the third sample comprises: performing, by the
master node, correlation peak detection of the second
synchronization sequence on the quantized form of the third
sample.
11. The method according to claim 9, wherein the second signal
further comprises a fourth synchronization sequence used for group
synchronization, and a second offset exists between a first element
of the fourth synchronization sequence and a first element of the
second synchronization sequence; and detecting, by the master node,
of the second synchronization sequence from the quantized form of
the third sample comprises: determining, by the master node, a
third location, wherein the third location is a location of the
first element of the fourth synchronization sequence in the
quantized form of the third sample; determining, by the master
node, a fourth location based on the third location and the second
offset, wherein the fourth location is a location of the first
element of the second synchronization sequence in the quantized
form of the third sample; obtaining, by the master node, a
quantized form of a fourth sample based on the fourth location,
wherein the third sample comprises the fourth sample; and
detecting, by the master node, the second synchronization sequence
from the quantized form of the fourth sample.
12. The method according to claim 11, wherein the determining, by
the master node, of the third location comprises: performing, by
the master node, correlation peak detection of the fourth
synchronization sequence on the quantized form of the third sample
to determine the third location; and detecting, by the master node,
of the second synchronization sequence from the quantized form of
the fourth sample comprises: performing, by the master node,
correlation peak detection of the second synchronization sequence
on the quantized form of the fourth sample.
13. The method according to claim 8, wherein the sending, by a
master node, of the first signal to a slave node comprises:
generating, by the master node, an encoded codeword; inserting, by
the master node, the first synchronization sequence into the
encoded codeword; processing, by the master node, the encoded
codeword into which the first synchronization sequence is inserted
to generate the first signal; and sending, by the master node, the
first signal to the slave node.
14. The method according to claim 13, further comprising:
inserting, by the master node into the encoded codeword, a third
synchronization sequence used for group synchronization, wherein a
first offset exists between a first element of the third
synchronization sequence and a first element of the first
synchronization sequence.
15. A node, comprising: a memory configured to store a computer
program instruction; and a processor coupled to the memory, wherein
the computer program instruction causes the node to be configured
to: receive a first signal from a master node, wherein the first
signal comprises a first synchronization sequence; detect the first
synchronization sequence from the first signal, wherein a moment of
detecting the first synchronization sequence is T2; receive first
information from the master node, wherein the first information
indicates a moment T1 at which the master node sends the first
synchronization sequence; send a second synchronization sequence to
the master node, wherein a moment of sending the second
synchronization sequence is T3, and the second synchronization
sequence is inserted at the channel layer of the slave node; and
receive second information from the master node, wherein the second
information is used to indicate a moment T4 at which the master
node detects a quantized form of the second synchronization
sequence; and perform time synchronization between the slave node
and the master node based on T1, T2, T3, and T4.
16. The node according to claim 14, wherein the computer program
instruction further causes the node to be configured to: sample the
first signal to obtain a first sample; quantize the first sample to
obtain a quantized form of the first sample; and detect the first
synchronization sequence from the quantized form of the first
sample.
17. The node according to claim 15, wherein the computer program
instruction causes the node to be configured to: perform
correlation peak detection of the first synchronization sequence on
the quantized form of the first sample.
18. The node according to claim 16, wherein the first signal
further comprises a third synchronization sequence used for group
synchronization, and a first offset exists between a first element
of the third synchronization sequence and a first element of the
first synchronization sequence; and the computer program
instruction further causes the node to be configured to: determine
a first location, wherein the first location is a location of the
first element of the third synchronization sequence in the
quantized form of the first sample; determine a second location
based on the first location and the first offset, wherein the
second location is a location of the first element of the first
synchronization sequence in the quantized form of the first sample;
obtain a quantized form of a second sample based on the second
location, wherein the first sample comprises the second sample; and
detect the first synchronization sequence from the quantized form
of the second sample.
19. The node according to claim 17, wherein the computer program
instruction causes the node to be configured to: perform
correlation peak detection of the third synchronization sequence on
the quantized form of the first sample to determine the first
location; and perform correlation peak detection of the first
synchronization sequence on the quantized form of the second
sample.
20. The node according to claim 15, wherein the computer program
instruction causes the processor to be configured to: generate an
encoded codeword; insert the second synchronization sequence into
the encoded codeword; process the encoded codeword into which the
second synchronization sequence is inserted to generate a second
signal; and send, by the slave node, the second signal to the
master node.
21. The node according to claim 20, wherein the computer program
instruction further causes the processor to be configured to:
insert a fourth synchronization sequence used for group
synchronization, wherein a second offset exists between a first
element of the fourth synchronization sequence and a first element
of the second synchronization sequence.
22. A node, comprising: a memory configured to store a computer
program instruction; and a processor coupled to the memory, wherein
the computer program instruction causes the node to be configured
to: send a first signal to a slave node, wherein the first signal
comprises a first synchronization sequence, and the first
synchronization sequence is inserted at a channel layer of the
master node; send first information to the slave node, wherein the
first information indicates a moment T1 at which the master node
sends the first synchronization sequence; receive a second signal
from the slave node, wherein the second signal comprises a second
synchronization sequence; detect the second synchronization
sequence from the second signal, wherein a moment of detecting the
second synchronization sequence is T4; and send second information
to the slave node, wherein the second information indicates T4, and
T1 and T4 are used for time synchronization between the master node
and the slave node.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 16/914,453, filed on Jun. 28, 2020, which is a
continuation of International Application No. PCT/CN2017/120075,
filed on Dec. 29, 2017, both of which are hereby incorporated by
reference in their entireties.
TECHNICAL FIELD
[0002] The embodiments relate to the communications field, and in
particular, to a time synchronization method, apparatus, and
system.
BACKGROUND
[0003] A full name of the Institute of Electrical and Electronics
Engineers (IEEE) 1588 protocol is "Standard for a Precision Clock
Synchronization Protocol for Networked Measurement and Control
Systems", which defines a Precision Time Protocol (PTP). A basic
function of the Precision Time Protocol is to maintain
synchronization between a most precise clock and other clocks in a
distributed network. In actual application, IEEE 1588 is a
master-slave synchronization system. In a synchronization process
of the system, a master node periodically releases a time
synchronization packet and timestamp information, a slave node
obtains the related time synchronization packet and timestamp
information by exchanging a packet with the master node and
calculates a line time delay and a time difference between the
master node and the slave node. The slave node then uses the time
difference to adjust a local time, so that a slave node time is
consistent with a master node time.
[0004] With development of communications technologies, an
increasingly strict requirement is imposed on an offset of time
synchronization between base stations in a communications scenario.
For example, in a 5th Generation (5G) mobile communications
network, an offset of time synchronization between base stations is
required to fall within 100 ns, imposing a strict requirement on
time synchronization in an optical switching network. For example,
a time synchronization precision loss caused by a single-hop device
needs to be controlled to fall within 5 ns. However, in an optical
transport network at a metropolitan convergence layer, a photonic
integrated device (PID) scenario is usually used. In this scenario,
no dedicated optical supervisory channel (OSC) is used to transmit
a 1588 time synchronization packet, and the 1588 synchronization
packet needs to be transmitted through an electric supervisory
channel (ESC). During transmission through the ESC channel, all
time synchronization packet data needs to be forwarded by using a
line-side optical module. As an optical module becomes more
complex, delay uncertainty caused by the optical module is higher.
For example, the delay uncertainty is usually above a magnitude of
10 ns, causing a bottleneck to a 5G high-precision time
synchronization technology.
SUMMARY
[0005] Various embodiments can provide a time synchronization
method, apparatus, and system, to improve precision of time
synchronization.
[0006] According to a first aspect, a time synchronization method
is provided, including: receiving, by a slave node, a first signal
from a master node, where the first signal includes a first
synchronization sequence; sampling, by the slave node, the first
signal, to obtain a first sample; quantizing, by the slave node,
the first sample, to obtain a quantized form of the first sample;
detecting, by the slave node, the first synchronization sequence
from the quantized form of the first sample, where a moment of
detecting the first synchronization sequence is T2; receiving, by
the slave node, first information from the master node, where the
first information is used to indicate a moment T1 at which the
master node sends the first synchronization sequence; sending, by
the slave node, a second synchronization sequence to the master
node, where a moment of sending the second synchronization sequence
is T3; receiving, by the slave node, second information from the
master node, where the second information is used to indicate a
moment T4 at which the master node detects a quantized form of the
second synchronization sequence; and performing, by the slave node,
time synchronization between the slave node and the master node
based on T1, T2, T3, and T4.
[0007] In this embodiment, time synchronization is performed
between the master node and the slave node by sending the first
synchronization sequence and the second synchronization sequence,
and the moments of receiving the synchronization sequences are
determined when the synchronization sequences are in the quantized
forms. Therefore, relatively few types of signal processing are
performed on the synchronization sequences, so that delay
uncertainty caused by different signal processing can be reduced,
thereby improving precision of time synchronization.
[0008] In an example implementation, the detecting, by the slave
node, the first synchronization sequence from the quantized form of
the first sample includes: performing, by the slave node,
correlation peak detection of the first synchronization sequence on
the quantized form of the first sample.
[0009] In an example implementation, the first signal further
includes a third synchronization sequence used for group
synchronization, and a first offset exists between a first element
of the third synchronization sequence and a first element of the
first synchronization sequence; and the detecting, by the slave
node, the first synchronization sequence from the quantized form of
the first sample includes: determining, by the slave node, a first
location, where the first location is a location of the first
element of the third synchronization sequence in the quantized form
of the first sample; determining, by the slave node, a second
location based on the first location and the first offset, where
the second location is a location of the first element of the first
synchronization sequence in the quantized form of the first sample;
obtaining, by the slave node, a quantized form of a second sample
based on the second location, where the first sample includes the
second sample; and detecting, by the slave node, the first
synchronization sequence from the quantized form of the second
sample.
[0010] In this embodiment, the first offset exists between the
third synchronization sequence used for group synchronization and
the first synchronization sequence. Therefore, after determining
the first location of the third synchronization sequence in the
quantized form of the first sample, the slave node may determine
the second location of the first synchronization sequence based on
the first offset, and obtain the quantized form of the second
sample based on the second location, to perform correlation peak
detection of the first synchronization sequence. This reduces an
operation amount of correlation peak detection, and improves
efficiency of correlation peak detection, thereby improving
efficiency of time synchronization between the master node and the
slave node.
[0011] In an example implementation, the determining, by the slave
node, a first location includes: performing, by the slave node,
correlation peak detection of the third synchronization sequence on
the quantized form of the first sample, to determine the first
location; and the detecting, by the slave node, the first
synchronization sequence from the quantized form of the second
sample includes: performing, by the slave node, correlation peak
detection of the first synchronization sequence on the quantized
form of the second sample.
[0012] In an example implementation, the sending, by the slave
node, a second synchronization sequence to the master node
includes: generating, by the slave node, an encoded codeword;
inserting, by the slave node, the second synchronization sequence
into the encoded codeword, where a moment of inserting the second
synchronization sequence is T3; processing, by the slave node, the
encoded codeword into which the second synchronization sequence is
inserted, to generate a second signal; and sending, by the slave
node, the second signal to the master node.
[0013] In this embodiment, time synchronization is performed
between the master node and the slave node by sending the first
synchronization sequence and the second synchronization sequence,
and T3 used for time synchronization is a moment of inserting the
second synchronization sequence after encoding. Therefore,
relatively few types of signal processing are performed on the
second synchronization sequence before the second synchronization
sequence is detected, so that delay uncertainty caused by different
signal processing can be reduced, thereby improving precision of
time synchronization.
[0014] In an example implementation, the slave node inserts, into
the encoded codeword, a fourth synchronization sequence used for
group synchronization, where a second offset exists between a first
element of the fourth synchronization sequence and a first element
of the second synchronization sequence.
[0015] In this embodiment, the second offset exists between the
fourth synchronization sequence used for group synchronization and
the second synchronization sequence. Therefore, after determining a
third location of the fourth synchronization sequence, the master
node may extract, based on the second offset, a quantized form that
is of a fourth sample and in which the second synchronization
sequence is located, to perform correlation peak detection of the
second synchronization sequence. This reduces an operation amount
of correlation peak detection, and improves efficiency of
correlation peak detection, thereby improving efficiency of time
synchronization between the master node and the slave node.
[0016] In an example implementation, before the receiving, by a
slave node, a first signal from a master node, the method further
includes: receiving, by the slave node, first primary
synchronization information from the master node, where the first
primary synchronization information is used to trigger the slave
node to detect whether the signal received by the slave node from
the master node includes the first synchronization sequence.
[0017] In this embodiment, the master node sends the first primary
synchronization information to the slave node, to instruct the
slave node to trigger detection of the first synchronization
sequence, so that the slave node may perform detection in a time
window starting from a moment of receiving the first primary
synchronization information, instead of continuously performing
detection, thereby improving efficiency of detecting the first
synchronization sequence.
[0018] In an example implementation, before the sending, by the
slave node, a second synchronization sequence to the master node,
the method further includes: sending, by the slave node, first
secondary synchronization information to the master node, where the
first secondary synchronization information is used to trigger the
master node to detect whether the signal from the slave node
includes the second synchronization sequence.
[0019] In this embodiment, the slave node sends the first secondary
synchronization information to the master node, to instruct the
master node to trigger detection of the second synchronization
sequence, so that the master node may perform detection in a time
window starting from a moment of receiving the first secondary
synchronization information, instead of continuously performing
detection, thereby improving efficiency of detecting the second
synchronization sequence.
[0020] In an example implementation, after the sending, by the
slave node, a second synchronization sequence to the master node,
the method further includes: sending, by the slave node, second
secondary synchronization information to the master node, where the
second secondary synchronization information is used to indicate
that the slave node has sent the second synchronization
sequence.
[0021] In this embodiment, the slave node sends the second
secondary synchronization information to the master node, to
indicate that the second synchronization sequence has been sent.
Therefore, after receiving the second secondary synchronization
information, the master node may stop detecting the second
synchronization sequence. This can avoid a resource waste caused by
continuously performing correlation peak detection when the master
node fails to detect the second synchronization sequence.
Therefore, a protection mechanism exists when detection of the
second synchronization sequence fails, thereby improving time
synchronization efficiency.
[0022] In an example implementation, the receiving, by the slave
node, second information from the master node includes: when the
master node detects the second synchronization sequence, receiving,
by the slave node, the second information from the master node; and
further includes: when the master node detects no second
synchronization sequence, receiving, by the slave node, second
primary synchronization information from the master node, where the
second primary synchronization information is used to indicate that
the master node fails to detect the second synchronization
sequence.
[0023] In this embodiment, when the master node fails to detect the
second synchronization sequence, the master node sends the second
primary synchronization information to the slave node, to indicate
that detection of the second synchronization sequence fails.
Therefore, a protection mechanism exists when detection of the
second synchronization sequence fails, so that the slave node
discards invalid data, thereby improving time synchronization
efficiency.
[0024] According to a second aspect, a time synchronization method
is provided, including: sending, by a master node, a first signal
to a slave node, where the first signal includes a first
synchronization sequence; sending, by the master node, first
information to the slave node, where the first information is used
to indicate a moment T1 at which the master node sends the first
synchronization sequence; receiving, by the master node, a second
signal from the slave node, where the second signal includes a
second synchronization sequence; sampling, by the master node, the
second signal, to obtain a third sample; quantizing, by the master
node, the third sample, to obtain a quantized form of the third
sample; detecting, by the master node, the second synchronization
sequence from the quantized form of the third sample, where a
moment of detecting the second synchronization sequence is T4; and
sending, by the master node, second information to the slave node,
where the second information is used to indicate T4, and T1 and T4
are used for time synchronization between the master node and the
slave node.
[0025] In this embodiment, time synchronization is performed
between the master node and the slave node by sending the first
synchronization sequence and the second synchronization sequence,
and moments of receiving the synchronization sequences are
determined when the synchronization sequences are in the quantized
forms. Therefore, relatively few types of signal processing are
performed on the synchronization sequences, so that delay
uncertainty caused by different signal processing can be reduced,
thereby improving precision of time synchronization.
[0026] In an example implementation, the detecting, by the master
node, the second synchronization sequence from the quantized form
of the third sample includes: performing, by the master node,
correlation peak detection of the second synchronization sequence
on the quantized form of the third sample.
[0027] In an example implementation, the second signal further
includes a fourth synchronization sequence used for group
synchronization, and a second offset exists between a first element
of the fourth synchronization sequence and a first element of the
second synchronization sequence; and the detecting, by the master
node, the second synchronization sequence from the quantized form
of the third sample includes: determining, by the master node, a
third location, where the third location is a location of the first
element of the fourth synchronization sequence in the quantized
form of the third sample; determining, by the master node, a fourth
location based on the third location and the second offset, where
the fourth location is a location of the first element of the
second synchronization sequence in the quantized form of the third
sample; obtaining, by the master node, a quantized form of a fourth
sample based on the fourth location, where the third sample
includes the fourth sample; and detecting, by the master node, the
second synchronization sequence from the quantized form of the
fourth sample.
[0028] In this embodiment, the second offset exists between the
fourth synchronization sequence used for group synchronization and
the second synchronization sequence. Therefore, after determining
the third location of the fourth synchronization sequence, the
master node may extract, based on the second offset, the quantized
form that is of the fourth sample and in which the second
synchronization sequence is located, to perform correlation peak
detection of the second synchronization sequence. This reduces an
operation amount of correlation peak detection, and improves
efficiency of correlation peak detection, thereby improving
efficiency of time synchronization between the master node and the
slave node.
[0029] In an example implementation, the determining, by the master
node, a third location includes: performing, by the master node,
correlation peak detection of the fourth synchronization sequence
on the quantized form of the third sample, to determine the third
location; and the detecting, by the master node, the second
synchronization sequence from the quantized form of the fourth
sample includes: performing, by the master node, correlation peak
detection of the second synchronization sequence on the quantized
form of the fourth sample.
[0030] In an example implementation, the sending, by a master node,
a first signal to a slave node includes: generating, by the master
node, an encoded codeword; inserting, by the master node, the first
synchronization sequence into the encoded codeword, where a moment
of inserting the first synchronization sequence is T1; processing,
by the master node, the encoded codeword into which the first
synchronization sequence is inserted, to generate the first signal;
and sending, by the master node, the first signal to the slave
node.
[0031] In an example implementation, the method further includes:
inserting, by the master node into the encoded codeword, a third
synchronization sequence used for group synchronization, where a
first offset exists between a first element of the third
synchronization sequence and a first element of the first
synchronization sequence.
[0032] In this embodiment, the first offset exists between the
third synchronization sequence used for group synchronization and
the first synchronization sequence. Therefore, after determining
the first location of the third synchronization sequence in the
quantized form of the first sample, the slave node may determine
the second location of the first synchronization sequence based on
the first offset, and obtain the quantized form of the second
sample based on the second location, to perform correlation peak
detection of the first synchronization sequence. This reduces an
operation amount of correlation peak detection, and improves
efficiency of correlation peak detection, thereby improving
efficiency of time synchronization between the master node and the
slave node.
[0033] In an example implementation, before the sending, by a
master node, a first signal to a slave node, the method further
includes: sending, by the master node, first primary
synchronization information to the slave node, where the first
primary synchronization information is used to trigger the slave
node to detect whether the signal received by the slave node from
the master node includes the first synchronization sequence.
[0034] In this embodiment, the master node sends the first primary
synchronization information to the slave node, to instruct the
slave node to trigger detection of the first synchronization
sequence, so that the slave node may perform detection in a time
window starting from a moment of receiving the first primary
synchronization information, instead of continuously performing
detection, thereby improving efficiency of detecting the first
synchronization sequence.
[0035] In an example implementation, before the receiving, by the
master node, a second signal from the slave node, the method
further includes: receiving, by the master node, first secondary
synchronization information from the slave node, where the first
secondary synchronization information is used to trigger the master
node to detect whether the signal from the slave node includes the
second synchronization sequence.
[0036] In this embodiment, the slave node sends the first secondary
synchronization information to the master node, to instruct the
master node to trigger detection of the second synchronization
sequence, so that the master node may perform detection in a time
window starting from a moment of receiving the first secondary
synchronization information, instead of continuously performing
detection, thereby improving efficiency of detecting the second
synchronization sequence.
[0037] In an example implementation, after the receiving, by the
master node, a second signal from the slave node, the method
further includes: receiving, by the master node, second secondary
synchronization information from the slave node, where the second
secondary synchronization information is used to indicate that the
slave node has sent the second synchronization sequence.
[0038] In this embodiment, the slave node sends the second
secondary synchronization information to the master node, to
indicate that the second synchronization sequence has been sent.
Therefore, after receiving the second secondary synchronization
information, the master node may stop detecting the second
synchronization sequence. This can avoid a resource waste caused by
continuously performing correlation peak detection when the master
node fails to detect the second synchronization sequence.
Therefore, a protection mechanism exists when detection of the
second synchronization sequence fails, improving time
synchronization efficiency.
[0039] In an example implementation, the sending, by the master
node, second information to the slave node includes: when the
master node detects the second synchronization sequence, sending,
by the master node, the second information to the slave node; and
further includes: when the master node detects no second
synchronization sequence, sending, by the master node, second
primary synchronization information to the slave node, where the
second primary synchronization information is used to indicate that
the master node fails to detect the second synchronization
sequence.
[0040] In this embodiment, when the master node fails to detect the
second synchronization sequence, the master node sends the second
primary synchronization information to the slave node, to indicate
that detection of the second synchronization sequence fails.
Therefore, a protection mechanism exists when detection of the
second synchronization sequence fails, so that the slave node
discards invalid data, thereby improving time synchronization
efficiency.
[0041] According to a third aspect, a node is provided, where the
node is configured to perform the method implemented by a slave
node in any one of the first aspect or the possible implementations
of the first aspect. For example, the node includes a module
configured to perform the method in any one of the first aspect or
the possible implementations of the first aspect.
[0042] According to a fourth aspect, a node is provided, where the
node is configured to perform the method implemented by a master
node in any one of the second aspect or the possible
implementations of the second aspect. For example, the node
includes a module configured to perform the method in any one of
the second aspect or the possible implementations of the second
aspect.
[0043] According to a fifth aspect, a node is provided, where the
node includes a communications interface, a memory, a processor,
and a bus system. The communications interface, the memory, and the
processor are connected by using the bus system. The memory is
configured to store an instruction. The processor is configured to
execute the instruction stored in the memory, to control the
communications interface to receive a signal and/or send a signal.
In addition, when the processor executes the instruction stored in
the memory, the processor can perform the method performed by a
slave node in any one of the first aspect or the possible
implementations of the first aspect.
[0044] According to a sixth aspect, a node is provided, where the
node includes a communications interface, a memory, a processor,
and a bus system. The communications interface, the memory, and the
processor are connected by using the bus system. The memory is
configured to store an instruction. The processor is configured to
execute the instruction stored in the memory, to control the
communications interface to receive a signal and/or send a signal.
In addition, when the processor executes the instruction stored in
the memory, the processor can perform the method performed by a
master node in any one of the second aspect or the possible
implementations of the second aspect.
[0045] According to a seventh aspect, a master-slave
synchronization system is provided, where the system includes the
nodes in the third aspect and the fourth aspect, or the system
includes the nodes in the fifth aspect and the sixth aspect.
[0046] According to an eighth aspect, a computer readable medium is
provided, and is configured to store a computer program, and the
computer program includes an instruction used to perform the method
in any one of the first aspect or the possible implementations of
the first aspect.
[0047] According to a ninth aspect, a computer readable medium is
provided, and is configured to store a computer program, and the
computer program includes an instruction used to perform the method
in any one of the second aspect or the possible implementations of
the second aspect.
BRIEF DESCRIPTION OF DRAWINGS
[0048] FIG. 1 is a schematic diagram of a process of time
synchronization between a master node and a slave node in a related
technology;
[0049] FIG. 2 is a schematic diagram of an application environment
according to an embodiment;
[0050] FIG. 3 is a schematic diagram of an internal structure of an
optical module in a related technology;
[0051] FIG. 4 is a schematic diagram of an internal structure of an
optical module according to an embodiment;
[0052] FIG. 5 is a schematic diagram of a frame of inserting a
synchronization sequence according to an embodiment;
[0053] FIG. 6 is a schematic diagram of detecting a synchronization
sequence according to an embodiment;
[0054] FIG. 7 is a schematic flowchart of a time synchronization
method according to an embodiment;
[0055] FIG. 8 is a schematic flowchart of a time synchronization
method according to another embodiment;
[0056] FIG. 9 is a schematic structural diagram of a node according
to an embodiment;
[0057] FIG. 10 is a schematic structural diagram of a node
according to another embodiment;
[0058] FIG. 11 is a schematic structural diagram of a node
according to still another embodiment; and
[0059] FIG. 12 is a schematic structural diagram of a node
according to yet another embodiment.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0060] The solutions of the embodiments may be applied to various
communications systems, such as: an optical communications system,
a Global System for Mobile Communications (GSM), a Code Division
Multiple Access (CDMA) system, a Wideband Code Division Multiple
Access (WCDMA) system, a general packet radio service (GPRS), a
Long Term Evolution (LTE) system, an LTE frequency division duplex
(FDD) system, an LTE time division duplex (TDD) system, a Universal
Mobile Telecommunications System (UMTS), a Worldwide
Interoperability for Microwave Access (WiMAX) communications
system, a future 5th Generation (5G) system, or a New Radio (NR)
system.
[0061] A node (for example, a master node or a slave node) in
various embodiments in accordance with the disclosure may be a
device used for communicating with a terminal device. The node may
be a base transceiver station (BTS) in the GSM or the (CDMA system,
or may be a NodeB (NB) in the WCDMA system, or may be an evolved
NodeB (eNB or eNodeB) in the LTE system, or may be a radio
controller in a cloud radio access network (CRAN) scenario; or the
network device may be a relay station, an access point, an
in-vehicle device, a wearable device, a network device in a future
5G network, a network device in a future evolved PLMN network, or
the like. This is not limited in the embodiments.
[0062] The following describes the solutions with reference to
accompanying drawings.
[0063] For ease of understanding, the following describes concepts
of some terms used in the embodiments.
[0064] Optical module: A function of the optical module is
optical-to-electrical conversion. After processing data, a transmit
end converts an electrical signal into an optical signal, and after
the optical signal is transmitted by using an optical fiber, a
receive end converts the optical signal into an electrical signal
and performs lossless restoration on the data.
[0065] Serializer/deserializer (serdes, SDS): is a module used for
serial/parallel conversion.
[0066] Framer/deframer (FRM): a frame mapping/demapping module in
an optical module. The framer/deframer can map a constant bit rate
(CBR) service to an optical channel transport unit (OTU)
service.
[0067] Transmission digital signal processor (Tx DSP): a digital
signal processing module in a sending direction, configured to
preprocess a to-be-sent signal, for example, perform channel
equalization, or perform noise reduction processing on the
to-be-sent signal.
[0068] Reception digital signal processor (Rx DSP): a digital
signal processing module in a receiving direction, which may
perform determining on a received signal. Determining means
determining a quantized digital signal as a binary digital signal.
The received digital signal processor may further perform group
synchronization on received signals. During digital communication,
generally, a specific quantity of elements form a "word" or
"sentence", for example, form a "group" to be transmitted. Group
synchronization is to identify a start/end moment of a digital
information group ("word" or "sentence"), or to provide a "start"
moment and an "end" moment of each group. Group synchronization is
sometimes referred to as frame synchronization. To implement group
synchronization, some special code words may be inserted into a
digital information stream as a head/tail mark of each group. These
special code words may be a synchronization sequence used for group
synchronization. An element is a basic signal unit that carries an
information amount. For example, an element may be symbols that are
used to represent a binary number and that have a same time
interval.
[0069] Electrical-to-optical conversion (E/O) module: configured to
convert an electrical signal into an optical signal.
[0070] Optical-to-electrical conversion (O/E) module: configured to
convert an optical signal into an electrical signal.
[0071] Digital-to-analog conversion circuit (DAC): a digital signal
processing module in a sending direction, configured to convert a
digital signal into an analog signal.
[0072] Analog-to-digital conversion circuit (ADC): a digital signal
processing module in a receiving direction, configured to convert
an analog signal into a digital signal. The DAC may be configured
to sample an input analog signal, to obtain a sample. The sample is
then quantized to obtain a quantized form of the sample. The sample
obtained through sampling may be a digital signal that is discrete
in time domain, and the quantized form of the sample (or a
quantized sample) may be a digital signal that is discrete in both
time domain and amplitude.
[0073] First in first out (FIFO): used to buffer data.
[0074] Forward error correction (FEC): a data encoding technology,
in which a receive end may be configured to verify a detection
error in transmission. In an FEC manner, a receive end not only can
discover an error of data, but also can determine a location of an
error occurring in a binary element, to correct the error.
[0075] Channel equalization: an anti-fading measure used to improve
transmission performance of a communications system in a fading
channel.
[0076] Correlation peak: an autocorrelation operation performed on
a segment of signal sequence. When signals overlap, autocorrelation
energy is highest, and an energy peak that is apparently different
from those of other locations can be seen.
[0077] Synchronization sequence used for group synchronization: a
specific element sequence, used for synchronization and channel
estimation at a receive end.
[0078] FIG. 1 is a schematic diagram of a process of time
synchronization between a master node and a slave node in a related
technology. The following first describes a synchronization process
of the 1588 protocol in a related technology with reference to FIG.
1.
[0079] S101. A master node (master) sends a first synchronization
(sync) packet to a slave node (slave), and records a sending moment
T1 into a register.
[0080] S102. The slave node receives the first synchronization
packet and records a moment T2 of receiving the first
synchronization packet.
[0081] S103. The master node sends a Follow_up packet to the slave
node, where the "Follow_up" packet includes the moment T1.
[0082] S104. The slave node sends a Delay_ReqDelay packet to the
master node and records a moment T3 of sending the Delay_Req
packet.
[0083] S105. The master node receives the Delay_Req packet and
records a moment T4 of receiving the Delay_Req packet.
[0084] S106. The master node sends a Delay_RespDelay packet to the
slave node, where the Delay_Resp packet includes T4.
[0085] S107. The slave node may calculate a delayDelay and a time
offset between the master node and the slave node based on T1 to
T4. A calculation formula is as follows:
Delay = ( T .times. 2 - T .times. 1 ) + ( T .times. 4 - T .times. 3
) 2 ( 1 ) Offset = ( T .times. 2 - T .times. 1 ) - ( T .times. 4 -
T .times. 3 ) 2 ( 2 ) ##EQU00001##
[0086] Delay is used to represent a delay, and the delay represents
a delay time caused in network transmission. Offset is used to
indicate an offset, and the offset represents a time difference
between a slave clock and a master clock.
[0087] The slave node may adjust a clock of the slave node based on
a calculated delay and offset, to synchronize the clock with that
of the master node.
[0088] The following describes an application environment of this
embodiment with reference to FIG. 2. FIG. 2 shows a module through
which a signal used for time synchronization between the master
node and the slave node passes. As shown in FIG. 2, on a master
node side, a signal is transmitted to an optical fiber after
passing through a system clock module, a service board, and an
optical module, and is then sent to the slave node. After the slave
node receives the signal by using the optical fiber, the signal
passes through an optical module and a service board, and then
arrives at a system clock module.
[0089] The service board may also be referred to as a line card and
may be configured to generate a time synchronization pulse signal
and perform timestamping and protocol processing.
[0090] The system clock module may be a clock of a network element
device and is configured to provide synchronization timing and time
information for all service boards on the network element device.
The system clock module may be configured to implement timestamp
calculation, filtering, and adjustment. For example, the network
element device may be the node in this embodiment.
[0091] A line-side optical module is equivalent to a service line
and introduces a delay during time synchronization. In a related
technology, an optical module can support only a delay report
function. The optical module may read a location of an FIFO
waterline inside the optical module to calculate uplink and
downlink delays. However, precision is relatively low in this
manner. For example, in the related technology, precision of only
about 20 ns can be implemented.
[0092] FIG. 3 is a schematic diagram of an internal structure of an
optical module 30 in the related technology. FIG. 3 shows paths
through which an optical channel transport unit (OTU) service
passes in a sending direction and a receiving direction. A side of
an SDS module is connected to a service board, and a side of an
electrical-to-optical conversion (E/O) module or an
optical-to-electrical conversion (0/E) module is connected to an
optical fiber.
[0093] In an optical transport network, an OTU represents a framed
optical channel data information structure. The OTU may include a
data payload area and an overhead area. Alternatively, an OTUx may
be used to represent a framed optical channel data information
structure, x represents an order of an OTU service, and a higher
order indicates a higher rate. Packets and data sent in the optical
transport network may be carried over the OUT for transmission.
[0094] In the sending direction, the OTU service passes through the
SDS module, an FRM module, an FEC module, a Tx DSP module, a
digital-to-analog conversion circuit (DAC), and an E/O module. The
SDS module and the FRM belong to a service layer. The FEC module,
the Tx DSP module, the DAC, and the E/O module belong to a channel
layer. For example, a service on a DAC line card is sent to the
optical module by passing through the SDS. Inside the optical
module, the FRM implements OTUx service framing detection, and then
channel FEC encoding is performed, and channel equalization
algorithm processing is performed in the Tx DSP. The service passes
through the DAC and is converted by the E/O module into an optical
signal, and is sent to the optical fiber.
[0095] In the receiving direction, the OTU service successively
passes an O/E module, an ADC, an Rx DSP module, an FEC module, an
FRM module and an SDS module. The SDS module and the FRM belong to
the service layer. The FEC module, the Rx DSP module, the ADC, and
the O/E module belong to the channel layer. For example, the O/E
module and the ADC collect and obtain line sample data, and after
the Rx DSP performs channel equalization algorithm processing, FEC
error correction is performed, to implement lossless reception of
the service, and then the data is sent to the service board by
using the SDS after FRM framing.
[0096] According to the foregoing descriptions, in the related
technology, the uplink and downlink delays are calculated by
reading the location of the FIFO waterline inside the optical
module. During signal processing, the FIFO is located in a position
at an upper layer of the FEC, that is, located in a position at the
service layer. For example, at a receive end, after a time
synchronization packet is received from the optical fiber, the
signal needs to be processed by a plurality of modules before a
delay can be reported. A time synchronization method in the 1588
protocol is based on an ideal condition: Signals in a sending
direction and a receiving direction are processed at a same moment
inside a node. However, in actual application, processing moments
of a plurality of signal processing modules through which the
signal passes in the sending direction and the receiving direction
have an error, and delay uncertainty is caused, affecting precision
of time synchronization between a master node and a slave node. In
addition, more processing modules through which the signal passes
lead to larger delay uncertainty and lower precision of time
synchronization.
[0097] An embodiment provides a time synchronization method. A main
idea of the time synchronization method is to add a synchronization
sequence used for time synchronization to a signal sent by a
master/slave node, and to detect the synchronization sequence when
a received signal is in a quantized form, to determine a moment for
time synchronization. In this way, time synchronization can be
implemented at a lower layer during signal processing, thereby
reducing delay uncertainty and improving precision of time
synchronization.
[0098] In one embodiment, a synchronization sequence used for time
synchronization may be added to a signal of a transmit end, and a
receive end may perform synchronization and timestamping through
correlation peak detection of the synchronization sequence. In
addition, the service layer implements a process of time
synchronization between the master node and the slave node based on
a time stamp and an algorithm. The foregoing transmit end may be a
master node, the foregoing receive end may be a slave node, and the
foregoing synchronization sequence may replace the first
synchronization packet in S101 in FIG. 1. Alternatively, the
foregoing transmit end may be a slave node, the foregoing receive
end may also be a slave node, and the foregoing synchronization
sequence may replace the Delay_Req packet in S105 in FIG. 1.
[0099] The transmit end may add the synchronization sequence used
for time synchronization to an encoded codeword that is obtained
through encoding (for example, after FEC is performed). Then
processing may be performed based on the encoded codeword to which
the synchronization sequence is added, to generate a signal, and
send the signal to the receive end. The foregoing processing may
include, for example, preprocessing, analog-to-digital conversion,
and E/O conversion on the encoded codeword. The receive end may
detect a quantized form of the synchronization sequence, to
determine a moment of receiving the synchronization sequence. The
synchronization sequence is inserted after being encoded on a
transmit end side, and timestamping is performed before encoding on
a receive end side. Therefore, time synchronization can be
implemented at a lower layer during signal processing. Because
fewer types of processing are performed on the signal before the
quantized form of the synchronization sequence is detected, delay
uncertainty is reduced, thereby improving precision of time
synchronization.
[0100] In addition, the foregoing synchronization sequence may also
be referred to as a training sequence. A synchronization sequence
is an element sequence and may be used for time synchronization or
channel estimation at the receive end. A synchronization sequence
has high correlation operation orthogonality. For example, the
synchronization sequence has extremely strong autocorrelation
energy, but very low energy of co-correlation with any other
signal. In addition, the synchronization sequence can still
maintain the foregoing features relatively well after channel link
noise is superposed. With this characteristic, a synchronization
sequence insertion point can be searched for at the receive end by
using a correlation operation, that is, time synchronization can be
implemented. Synchronization sequence detection by using the
foregoing correlation operation may also be referred to as
correlation peak detection. The foregoing correlation operation is
a time-domain signal convolution. A convolution formula is shown as
follows:
c .function. ( n ) = k = 0 n .times. a .function. ( k ) .times. b
.function. ( n - k ) , .times. n = 0 ~ ( n .times. 1 + n .times. 2
) ( 3 ) ##EQU00002##
[0101] Here, c(n) represents a convolved sequence, a(k) represents
a convolution sequence a, b(n-k) represents a deconvolution of a
convolution sequence b, n represents a subscript serial number of a
convolution sequence result, k represents a subscript serial number
of a convolution sequence operation, n1 represents a length of the
convolution sequence a, and n2 represents a length of the
convolution sequence b.
[0102] FIG. 4 is a structural diagram of an optical module 40
according to this embodiment. As shown in FIG. 4, to implement the
time synchronization method in this embodiment, the optical module
40 further includes the following modules:
[0103] (1) Optical module time synchronization protocol and
algorithm (oTSPA) module: also referred to as an auto-negotiation
protocol algorithm module. The oTSPA module is a state machine that
is responsible for processing a synchronization sequence received
or sent by an optical module and is configured to implement
transmission of a time synchronization signal and ensure normal
transmission of the time synchronization signal by using a specific
handshake protocol. The oTSPA module may receive and process a
timestamp packet sent by a real time counter (RTC) and insert the
timestamp packet into OTU overheads; or place a timestamp packet
generated in a synchronization sequence at the channel layer in
service layer overheads for transmission. Further, the oTSPA may
drive a transmit end synchronization sequence insertion module to
insert the synchronization sequence used for time synchronization.
The oTSPA may also drive a receive end synchronization sequence
identification module to detect the synchronization sequence used
for time synchronization.
[0104] (2) Transmit end synchronization sequence insertion module:
inserts, driven by the auto-negotiation protocol algorithm, the
synchronization sequence used for time synchronization, and
generates a pulse signal corresponding to the synchronization
sequence and sends the pulse signal to the RTC for timestamping. As
shown in FIG. 4, after an encoded codeword passes through the
transmit end synchronization sequence insertion module, the
synchronization sequence used for time synchronization may be
inserted into the encoded codeword. In some embodiments, the
synchronization sequence used for time synchronization may be
inserted into the encoded codeword together with a synchronization
sequence used for group synchronization.
[0105] In some embodiments, when a time synchronization request is
initiated, the synchronization sequence used for time
synchronization may be inserted into a fixed location following the
synchronization sequence used for group synchronization. In
addition, a corresponding pulse signal is generated when the
synchronization sequence used for time synchronization is inserted,
and the pulse signal is sent to the RTC for timestamping. For
example, FIG. 5 is a schematic diagram of inserting, into an
encoded codeword of the transmit end, a synchronization sequence
used for time synchronization. As shown in FIG. 5, when a time
synchronization request needs to be initiated, the synchronization
sequence used for time synchronization may be inserted into a fixed
location following a synchronization sequence used for group
synchronization. Therefore, a location of the synchronization
sequence used for time synchronization may be obtained by using an
offset location of the synchronization sequence used for group
synchronization. A correlation operation of correlation peak
detection is performed on only one data block extracted from the
synchronization sequence used for time synchronization, so that
operation complexity can be reduced. In some embodiments, when the
time synchronization request is initiated, the synchronization
sequence may be inserted into the fixed location, or when no time
synchronization request is initiated, an overhead section
corresponding to the fixed location may be used to send a random
code.
[0106] In some embodiments, the transmit end may spare one time
synchronization sequence overhead location at an interval of a
fixed time unit, to ensure transmission bandwidth utilization.
[0107] In some embodiments, in some embodiments, there may be no
location association relationship between a synchronization
sequence used for time synchronization and a synchronization
sequence used for group synchronization.
[0108] (3) Receive end synchronization sequence identification
module: configured to identify a synchronization sequence in data
through a correlation operation, generate a corresponding pulse
signal, and send the pulse signal to the RTC for timestamping.
[0109] For example, FIG. 6 is a schematic diagram of a process in
which the receive end performs correlation peak detection of a
synchronization sequence. The receive end may perform correlation
peak detection on a data block obtained after ADC sampling and
serial/parallel conversion, and when a synchronization sequence
used for time synchronization is detected, generate a corresponding
pulse signal, and send the pulse signal to the RTC for
timestamping. In some embodiments, the receive end may first
perform correlation peak detection of a synchronization sequence
used for group synchronization, to determine a location of the
synchronization sequence used for group synchronization, and
determine a location of the synchronization sequence used for time
synchronization based on the location of the synchronization
sequence used for group synchronization. The receive end may
extract, based on the location of the synchronization sequence used
for time synchronization, a data segment in the location, and then
perform correlation peak detection on the extracted data segment,
and at a moment of detecting the synchronization sequence used for
time synchronization, generate a corresponding pulse signal, and
send the pulse signal to the RTC for timestamping.
[0110] (4) Real time counter (RTC): configured to generate a
timestamp based on a received pulse signal and send the timestamp
to the oTSPA module.
[0111] The following describes a time synchronization method 700
according to an embodiment in accordance with reference to FIG. 7.
The method 700 may be performed by a master node and a slave node.
As shown in FIG. 7, the method 700 includes the following
steps.
[0112] S701. The master node sends a first signal to the slave
node, where the first signal includes a first synchronization
sequence, and correspondingly, the slave node receives the first
signal from the master node, where a moment at which the master
node inserts the first synchronization sequence into an encoded
codeword corresponding to the first signal is T1, and a moment at
which the slave node detects the first synchronization sequence is
T2.
[0113] For example, the slave node samples the first signal to
obtain a first sample, quantizes the first sample to obtain a
quantized form of the first sample, and detects the first
synchronization sequence from the quantized form of the first
sample. The moment of detecting the first synchronization sequence
is T2.
[0114] A function of the foregoing first synchronization sequence
may be similar to that of the first synchronization packet in FIG.
1. The master node needs to record the moment T1 of sending the
first synchronization sequence and sends T1 to the slave node in
subsequent interaction. The slave node needs to record the moment
T2 of receiving the first synchronization sequence. T1 and T2 are
used for time synchronization between the master node and the slave
node.
[0115] In some embodiments, the slave node detects the first
synchronization sequence from the quantized form of the first
sample in two manners. In a first manner, the slave node directly
performs correlation peak detection of the first synchronization
sequence on the quantized form of the first sample. In a second
manner, the first signal further includes a third synchronization
sequence used for group synchronization, and a first offset exists
between a first element of the third synchronization sequence and a
first element of the first synchronization sequence; and the
detecting, by the slave node, the first synchronization sequence
from the quantized form of the first sample includes: determining,
by the slave node, a first location, where the first location is a
location of the first element of the third synchronization sequence
in the quantized form of the first sample; determining, by the
slave node, a second location based on the first location and the
first offset, where the second location is a location of the first
element of the first synchronization sequence in the quantized form
of the first sample; obtaining, by the slave node, a quantized form
of a second sample based on the second location, where the first
sample includes the second sample; and detecting, by the slave
node, the first synchronization sequence from the quantized form of
the second sample.
[0116] The determining, by the slave node, a first location
includes: performing, by the slave node, correlation peak detection
of the third synchronization sequence on the quantized form of the
first sample, to determine the first location; and the detecting,
by the slave node, the first synchronization sequence from the
quantized form of the second sample includes: performing, by the
slave node, correlation peak detection of the first synchronization
sequence on the quantized form of the second sample.
[0117] In this embodiment, the first offset exists between the
third synchronization sequence used for group synchronization and
the first synchronization sequence. Therefore, after determining
the first location of the third synchronization sequence in the
quantized form of the first sample, the slave node may determine
the second location of the first synchronization sequence based on
the first offset and obtain the quantized form of the second sample
based on the second location, to perform correlation peak detection
of the first synchronization sequence. This reduces an operation
amount of correlation peak detection, and improves efficiency of
correlation peak detection, thereby improving efficiency of time
synchronization between the master node and the slave node.
[0118] The slave node may generate a pulse signal corresponding to
T2 and perform timestamping at the moment of detecting the first
synchronization sequence. For a specific process of generating the
pulse signal corresponding to T2 and performing timestamping, refer
to content of the receive end synchronization sequence
identification module in FIG. 4.
[0119] Both the quantized form of the first sample and the
quantized form of the second sample are digital signals before a
binary digital signal is generated. In other words, the foregoing
quantized form is a signal discrete in both time and amplitude. For
example, the quantized form of the first sample may be a data block
obtained before FEC processing is performed.
[0120] 5702. The master node sends first information to the slave
node, where the first information is used to indicate a moment T1
at which the master node sends the first synchronization sequence,
and correspondingly, the slave node receives the first information
from the master node.
[0121] In some embodiments, a function of the first information is
similar to that of the Follow_up packet in FIG. 1. The first
information may also be carried in a packet.
[0122] In some embodiments, the master node may record T1. For
example, that the master node sends the first synchronization
sequence to the slave node at the moment T1 includes: generating,
by the master node, an encoded codeword; inserting, by the master
node, the first synchronization sequence into the encoded codeword,
where a moment of inserting the first synchronization sequence is
T1; processing, by the master node, the encoded codeword into which
the first synchronization sequence is inserted, to generate the
first signal; and sending, by the master node, the first signal to
the slave node. For example, the master node may generate a pulse
signal and perform timestamping when inserting the first
synchronization sequence, and a moment corresponding to the
timestamp is T1. For a specific process of generating the pulse
signal corresponding to T1 and performing timestamping, refer to
content related to the transmit end synchronization sequence
insertion module in FIG. 4.
[0123] For example, the master node may insert the foregoing first
synchronization sequence into an encoded codeword on which FEC
processing is performed and generate a timestamp corresponding to
T1.
[0124] S703. The slave node sends a second synchronization sequence
to the master node, where a moment of sending the second
synchronization sequence is T3, and correspondingly, the master
node receives the second synchronization sequence from the slave
node, where a moment at which the master node detects a quantized
form of the second synchronization sequence is T4.
[0125] A function of the foregoing second synchronization sequence
may be similar to that of the Delay_Req packet in FIG. 1. The slave
node may record T3, and the master node may record T4, and send T4
to the slave node in subsequent interaction. T3 and T4 are also
used for time synchronization between the master node and the slave
node.
[0126] In some embodiments, the slave node may record T3. In some
embodiments, that the slave node sends a second synchronization
sequence to the master node includes: generating, by the slave
node, an encoded codeword; inserting, by the slave node, the second
synchronization sequence into the encoded codeword, where a moment
of inserting the second synchronization sequence is T3; processing,
by the slave node, the encoded codeword into which the second
synchronization sequence is inserted, to generate a second signal;
and sending, by the slave node, the second signal to the master
node. For example, the slave node may generate a pulse signal and
perform timestamping when inserting the second synchronization
sequence, and a moment corresponding to the timestamp is T3. For a
specific process of generating the pulse signal corresponding to T3
and performing timestamping, refer to content related to the
transmit end synchronization sequence insertion module in FIG.
4.
[0127] For example, the slave node may insert the foregoing first
synchronization sequence into an encoded codeword on which FEC
processing is performed and generate a timestamp corresponding to
T3.
[0128] That the master node detects the second synchronization
sequence from a quantized form of the third sample, where the
moment of detecting the second synchronization sequence is T4
includes: receiving, by the master node, the second signal from the
slave node, where the second signal includes the second
synchronization sequence; sampling, by the master node, the second
signal, to obtain the third sample; quantizing, by the master node,
the third sample, to obtain the quantized form of the third sample;
and detecting, by the master node, the second synchronization
sequence from the quantized form of the third sample, where the
moment of detecting the second synchronization sequence is T4.
[0129] In some embodiments, the master node may detect the second
synchronization sequence from the quantized form of the third
sample in two manners. In a first manner, the master node directly
performs correlation peak detection of the second synchronization
sequence on the quantized form of the third sample. In a second
manner, the second signal further includes a fourth synchronization
sequence used for group synchronization, and a second offset exists
between a first element of the fourth synchronization sequence and
a first element of the second synchronization sequence; and the
detecting, by the master node, the second synchronization sequence
from the quantized form of the third sample includes: determining,
by the master node, a third location, where the third location is a
location of the first element of the fourth synchronization
sequence in the quantized form of the third sample; determining, by
the master node, a fourth location based on the third location and
the second offset, where the second location is a location of the
first element of the fourth synchronization sequence in the
quantized form of the third sample; obtaining, by the master node,
a quantized form of a fourth sample based on the fourth location,
where the third sample includes the fourth sample; and detecting,
by the master node, the second synchronization sequence from the
quantized form of the fourth sample.
[0130] The determining, by the master node, a third location
includes: performing, by the master node, correlation peak
detection of the fourth synchronization sequence on the quantized
form of the third sample, to determine the third location. The
detecting, by the master node, the second synchronization sequence
from the quantized form of the fourth sample includes: performing,
by the master node, correlation peak detection of the second
synchronization sequence on the quantized form of the fourth
sample.
[0131] In this embodiment, the second offset exists between the
fourth synchronization sequence used for group synchronization and
the second synchronization sequence. Therefore, after determining
the third location of the fourth synchronization sequence, the
master node may extract, based on the second offset, the quantized
form that is of the fourth sample and in which the second
synchronization sequence is located, to perform correlation peak
detection of the second synchronization sequence. This reduces an
operation amount of correlation peak detection, and improves
efficiency of correlation peak detection, thereby improving
efficiency of time synchronization between the master node and the
slave node.
[0132] The master node may generate a pulse signal corresponding to
T4 and perform timestamping at the moment of detecting the second
synchronization sequence. For a specific process of generating the
pulse signal corresponding to T4 and performing timestamping, refer
to content of the receive end synchronization sequence
identification module in FIG. 4.
[0133] S704. The master node sends second information to the slave
node, where the second information is used to indicate T4, and
correspondingly, the slave node receives the second information
from the master node.
[0134] In some embodiments, a function of the second information is
similar to that of the Delay_Resp packet in FIG. 1. The second
information may also be carried in a packet.
[0135] S705. The slave node performs time synchronization between
the slave node and the master node based on T1, T2, T3, and T4.
[0136] For example, the performing time synchronization between the
slave node and the master node based on T1, T2, T3, and T4 may be:
substituting, by the slave node, T1, T2, T3, and T4 into the
formula (1) and the formula (2) in FIG. 1, to calculate a delay and
a time offset between the master node and the slave node. The slave
node may adjust a time of the slave node based on the delay and the
time offset.
[0137] In this embodiment, time synchronization is performed
between the master node and the slave node by sending the first
synchronization sequence and the second synchronization sequence.
The moments T2 and T4 of receiving the synchronization sequences
are determined when the synchronization sequences are in the
quantized forms, and the moments T1 and T3 of sending the
synchronization sequences are subsequent to encoding. In other
words, the moments T1 and T3 of sending the synchronization
sequences are subsequent to encoding, and the moments T2 and T4 of
receiving the synchronization sequences are prior to decoding.
Therefore, in the foregoing time intervals, or in other words, in
an interval from T1 to T2 and an interval from T3 to T4, relatively
few types of signal processing are performed on the synchronization
sequences, so that delay uncertainty caused by different signal
processing can be reduced, thereby improving precision of time
synchronization.
[0138] In one solution of this embodiment, a synchronization
sequence is used to perform time synchronization. In this manner,
the synchronization sequence is detected at a channel layer, and it
is possible that a receive end cannot correctly detect the
synchronization sequence. Therefore, the following continues to
describe the method 700, which further includes a processing method
upon a failure in detecting a synchronization sequence.
[0139] In some embodiments, before the master node sends the first
synchronization sequence to the slave node, the method 700 further
includes: sending, by the master node, first primary
synchronization information to the slave node, where the first
primary synchronization information is used to trigger the slave
node to detect whether the signal received by the slave node from
the master node includes the first synchronization sequence.
Correspondingly, the slave node receives the first primary
synchronization information from the master node.
[0140] For example, after receiving the first primary
synchronization information, the slave node starts correlation peak
detection of the first synchronization sequence. If the slave node
still detects no first synchronization sequence after receiving the
first information, it indicates that the slave node fails to detect
the first synchronization sequence. The slave node stops detecting
the first synchronization sequence. In this case, the slave node
considers T2 indicated by the first information as invalid data,
and a new round of a time synchronization process is performed
between the master node and the slave node. In other words, the
slave node performs correlation peak detection of the first
synchronization sequence in a time window between a moment of
receiving the first primary synchronization information and a
moment of receiving the first information. If detection of the
first synchronization sequence in the time window fails, it
indicates that time synchronization fails, and a new round of the
time synchronization process needs to be started. Therefore, a
protection mechanism exits when detection of the first
synchronization sequence fails, so that the slave node discards
invalid data, thereby improving time synchronization
efficiency.
[0141] In this embodiment, the master node sends the first primary
synchronization information to the slave node, to instruct the
slave node to trigger detection of the first synchronization
sequence, so that the slave node may perform detection in the time
window starting from the moment of receiving the first primary
synchronization information, instead of continuously performing
detection, thereby improving efficiency of detecting the first
synchronization sequence.
[0142] In some embodiments, before the slave node sends the second
synchronization sequence to the master node, the method 700 further
includes: sending, by the slave node, first secondary
synchronization information to the master node, where the first
secondary synchronization information is used to trigger the master
node to detect whether the signal from the slave node includes the
second synchronization sequence.
[0143] Similar to the first primary synchronization information,
the slave node sends the first secondary synchronization
information to the master node before sending the second
synchronization sequence, to trigger the master node to detect the
second synchronization sequence, so that the master node does not
need to continuously perform detection.
[0144] In some embodiments, after the slave node sends the second
synchronization sequence to the master node, the method 700 further
includes: sending, by the slave node, second secondary
synchronization information to the master node, where the second
secondary synchronization information is used to indicate that the
slave node has sent the second synchronization sequence.
[0145] In this embodiment, after receiving the first secondary
synchronization information, the master node starts correlation
peak detection of the second synchronization sequence. If the
master node still detects no second synchronization sequence after
receiving the second secondary synchronization information, it
indicates that the master node fails to detect the second
synchronization sequence. The master node stops detecting the
second synchronization sequence. In this case, the master node
sends second primary synchronization information to the slave node,
and the information is used to indicate that the master node fails
to detect the second synchronization sequence, so that the slave
node considers previously recorded T3 as invalid data. In other
words, the master node performs correlation peak detection of the
second synchronization sequence in a time window between a moment
of receiving the first secondary synchronization information and a
moment of receiving the second secondary synchronization
information. If detection of the second synchronization sequence in
the time window fails, it indicates that time synchronization
fails, and a new round of the time synchronization process needs to
be started. Therefore, a protection mechanism exits when detection
of the second synchronization sequence fails, so that the slave
node discards invalid data, thereby improving time synchronization
efficiency.
[0146] In this embodiment, the slave node sends the second
secondary synchronization information to the master node, to
indicate that the second synchronization sequence has been sent.
Therefore, after receiving the second secondary synchronization
information, the master node may stop detecting the second
synchronization sequence. This can avoid a resource waste caused by
continuously performing correlation peak detection when the master
node fails to detect the second synchronization sequence.
Therefore, a protection mechanism exists when detection of the
second synchronization sequence fails, improving time
synchronization efficiency.
[0147] In an S704 part of the method 700, that the master node
sends second information to the slave node, or correspondingly, the
slave node receives the second information from the master node
includes: When the master node successfully detects the second
synchronization sequence, the master node sends the second
information to the slave node, and correspondingly, the slave node
receives the second information from the master node. The method
further includes: when the master node fails to detect the second
synchronization sequence, the master node sends the second primary
synchronization information to the slave node, where the second
primary synchronization information is used to indicate that the
master node fails to detect the second synchronization sequence,
and correspondingly, the slave node receives the second primary
synchronization information from the master node.
[0148] In this embodiment, when the master node fails to detect the
second synchronization sequence, the master node sends the second
primary synchronization information to the slave node, to indicate
that detection of the second synchronization sequence fails.
Therefore, a protection mechanism exists when detection of the
second synchronization sequence fails, so that the slave node
discards invalid data, thereby improving time synchronization
efficiency.
[0149] The following describes one example embodiment in accordance
with the disclosure with reference to FIG. 8. FIG. 8 is a schematic
diagram of a specific process of a time synchronization request. As
shown in FIG. 8, a method 800 includes the following steps.
[0150] S801. A master node sends first primary synchronization
information to a slave node, and correspondingly, the slave node
receives the first primary synchronization information.
[0151] For a function and definition of the first primary
synchronization information, refer to related descriptions in FIG.
7, and details are not described herein again.
[0152] In some embodiments, after receiving the first primary
synchronization information, the slave node may start correlation
peak detection of a first synchronization sequence.
[0153] In some embodiments, an oSTPA of the master node may send
the first primary synchronization information, and after receiving
the first primary synchronization information, an oSTPA of the
slave node triggers correlation peak detection of the first
synchronization sequence.
[0154] S802. The master node sends a first synchronization sequence
to the slave node and records a moment T1 of sending the first
synchronization sequence, and correspondingly, the slave node
receives the first synchronization sequence from the master node
and records a moment T2 of receiving the first synchronization
sequence.
[0155] In some embodiments, the master node may insert the first
synchronization sequence into a to-be-sent first signal, and the
slave node may detect the first synchronization sequence by using a
correlation peak detection function.
[0156] For example, implementation of inserting, by the master
node, the first synchronization sequence into an encoded codeword
corresponding to the first signal and a specific process of
detecting the first time synchronization training by the slave
node, refer to related descriptions in FIG. 4 to FIG. 7, and
details are not described herein again.
[0157] S803. The master node sends first information to the slave
node, where the first information is used to indicate the moment
T1, and correspondingly, the slave node receives the first
information, and obtains the moment T1.
[0158] In some embodiments, the first information may be carried in
a packet.
[0159] In some embodiments, if the slave node still detects no
first synchronization sequence after receiving the first
information, it indicates that the slave node fails to detect the
first synchronization sequence. Therefore, the slave node considers
the moment T1 indicated by the first information as invalid data
and discards a current round of a time synchronization
operation.
[0160] S804. The slave node sends first secondary synchronization
information to the master node, and correspondingly, the master
node receives the first secondary synchronization information.
[0161] For a function and definition of the first secondary
synchronization information, refer to related descriptions in FIG.
7, and details are not described herein again.
[0162] In some embodiments, after receiving the first secondary
synchronization information, the master node may start correlation
peak detection of a second synchronization sequence.
[0163] S805. The slave node sends a second synchronization sequence
to the master node, and records a sending moment T3, and
correspondingly, the master node receives the second
synchronization sequence, and records a receiving moment T4.
[0164] In some embodiments, the slave node may insert the second
synchronization sequence into a to-be-sent second signal, and the
master node may detect the second synchronization sequence by using
a correlation peak detection function.
[0165] For example, implementation of inserting, by the slave node,
the second synchronization sequence into an encoded codeword
corresponding to the second signal and a specific process of
detecting the second time synchronization training by the master
node, refer to related descriptions in FIG. 4 to FIG. 7, and
details are not described herein again.
[0166] S806. After sending the second synchronization sequence, the
slave node sends second secondary synchronization information to
the master node, and correspondingly, the master node receives the
second secondary synchronization information.
[0167] In some embodiments, if the master node still detects no
second synchronization sequence after receiving the second
secondary synchronization information, it indicates that the master
node fails to detect the second synchronization sequence.
[0168] S807. If the master node successfully detects the second
synchronization sequence, the master node sends second information
to the slave node; or if the master node fails to detect the second
time synchronization training, the master node sends second primary
synchronization information to the slave node; and correspondingly,
the slave node receives the second information, or the slave node
receives the second primary synchronization information.
[0169] The second information is used to indicate the moment
T4.
[0170] In some embodiments, the primary synchronization response
message may be used to indicate, to the slave node, that detection
of the second synchronization sequence fails. After receiving the
second primary synchronization information, the slave node may
consider T3 as invalid data.
[0171] S808. The slave node calculates a delay and a time offset
between the master node and the slave node based on T1 to T4, for
time synchronization between the master node and the slave
node.
[0172] In this embodiment, time synchronization is performed
between the master node and the slave node by sending the first
synchronization sequence and the second synchronization sequence,
and the moments T2 and T4 of receiving the synchronization
sequences are determined when the synchronization sequences are in
quantized forms. Therefore, in the foregoing time intervals, or in
other words, in an interval from T1 to T2 and an interval from T3
to T4, relatively few types of signal processing are performed on
the synchronization sequences, so that delay uncertainty caused by
different signal processing can be reduced, thereby improving
precision of time synchronization.
[0173] Further, the master node sends the first primary
synchronization information to the slave node, to instruct the
slave node to trigger detection of the first synchronization
sequence, so that the slave node may perform detection in the time
window, instead of continuously performing detection, thereby
improving efficiency of detecting the first synchronization
sequence.
[0174] The time synchronization method and apparatus in the
embodiments are described above in detail with reference to FIG. 1
to FIG. 8, and the following continues to describe an apparatus
according to an embodiment with reference to the accompanying
drawings.
[0175] FIG. 9 is a schematic block diagram of a node 900 according
to an embodiment. It should be understood that the node 900 can
perform steps that are performed by a slave node in FIG. 1 to FIG.
8. To avoid repetition, details are not described herein again. The
node 900 includes a processing unit 901 and a communications unit
902. The processing unit 901 is configured to: receive a first
signal from a master node by using the communications unit 902,
where the first signal includes a first synchronization sequence;
sample the first signal, to obtain a first sample; quantize the
first sample, to obtain a quantized form of the first sample;
detect the first synchronization sequence from the quantized form
of the first sample, where a moment of detecting the first
synchronization sequence is T2; receive first information from the
master node by using the communications unit 902, where the first
information is used to indicate a moment T1 at which the master
node sends the first synchronization sequence; send a second
synchronization sequence to the master node by using the
communications unit 902, where a moment of sending the second
synchronization sequence is T3; receive second information from the
master node by using the communications unit 902, where the second
information is used to indicate a moment T4 at which the master
node detects a quantized form of the second synchronization
sequence; and perform time synchronization between the slave node
and the master node based on T1, T2, T3, and T4.
[0176] FIG. 10 is a schematic block diagram of a node 1000
according to an embodiment. It should be understood that the node
1000 can perform steps that are performed by a master node in FIG.
1 to FIG. 8. To avoid repetition, details are not described herein
again. The node 1000 includes a processing unit 1001 and a
communications unit 1002. The processing unit 1001 is configured to
send a first signal to a slave node by using the communications
unit 1002, where the first signal includes a first synchronization
sequence; send first information to the slave node by using the
communications unit 1002, where the first information is used to
indicate a moment T1 at which the master node sends the first
synchronization sequence; receive a second signal from the slave
node by using the communications unit 1002, where the second signal
includes a second synchronization sequence; sample the second
signal, to obtain a third sample; quantize the third sample, to
obtain a quantized form of the third sample; detect the second
synchronization sequence from the quantized form of the third
sample, where a moment of detecting the second synchronization
sequence is T4; and send second information to the slave node by
using the communications unit 1002, where the second information is
used to indicate T4, and T1 and T4 are used for time
synchronization between the master node and the slave node.
[0177] FIG. 11 is a schematic structural diagram of a node 1100
according to an embodiment. As shown in FIG. 11, the node 1100
includes one or more processors 1130, one or more memories 1110,
and one or more communications interfaces 1120. The processor 1130
is configured to control the communications interface 1120 to
receive and send signals, and the memory 1110 is configured to
store a computer program. The processor 1130 is configured to
invoke the computer program from the memory 1110, and run the
computer program, so that the node 1100 performs a corresponding
procedure and/or operation performed by a slave node in the time
synchronization method embodiment. For brevity, details are not
described herein.
[0178] It should be noted that the node 900 shown in FIG. 9 may be
implemented by the node 1100 shown in FIG. 11. For example, the
communications unit 901 may be implemented by the communications
interface 1120 in FIG. 11. The processing unit 901 may be
implemented by the processor 1130.
[0179] FIG. 12 is a schematic structural diagram of a node 1200
according to an embodiment. As shown in FIG. 12, the node 1200
includes one or more processors 1230, one or more memories 1210,
and one or more communications interfaces 1220. The processor 1230
is configured to control the communications interface 1220 to
receive and send signals, and the memory 1210 is configured to
store a computer program. The processor 1230 is configured to
invoke the computer program from the memory 1210, and run the
computer program, so that the node 1200 performs a corresponding
procedure and/or operation performed by a master node in the time
synchronization method embodiment. For brevity, details are not
described herein.
[0180] It should be noted that the node 1000 shown in FIG. 10 may
be implemented by the node 1200 shown in FIG. 12. For example, the
communications unit 1001 may be implemented by the communications
interface 1220 in FIG. 12. The processing unit 1001 may be
implemented by the processor 1230.
[0181] A person of ordinary skill in the art may be aware that, in
combination with the examples described in the embodiments, units
and algorithm steps may be implemented by electronic hardware or a
combination of computer software and electronic hardware. Whether
the functions are performed by hardware or software depends on
particular applications and design constraint conditions of the
solutions. A person of ordinary skill in the art may use different
methods to implement the described functions for each particular
application, but it should not be considered that the
implementation goes beyond the scope of the embodiments.
[0182] It may be clearly understood by a person of ordinary skill
in the art that, for the purpose of convenient and brief
description, for a detailed working process of the foregoing
system, apparatus, and unit, reference may be made to a
corresponding process in the foregoing method embodiments, and
details are not described herein again.
[0183] In the several embodiments provided herein, it should be
understood that the disclosed system, apparatus, and method may be
implemented in other manners. For example, the described apparatus
embodiment is merely an example. For example, the unit division is
merely logical function division and may be other division in
actual implementation. For example, a plurality of units or
components may be combined or integrated into another system, or
some features may be ignored or not performed. In addition, the
displayed or discussed mutual couplings or direct couplings or
communication connections may be implemented by using some
interfaces. The indirect couplings or communication connections
between the apparatuses or units may be implemented in electronic,
mechanical, or other forms.
[0184] The units described as separate parts may or may not be
physically separate, and parts displayed as units may or may not be
physical units, may be located in one position, or may be
distributed on a plurality of network units. Some or all of the
units may be selected based on actual requirements to achieve the
objectives of the solutions of the embodiments.
[0185] In addition, functional units in the embodiments may be
integrated into one processing unit, or each of the units may exist
alone physically, or two or more units are integrated into one
unit.
[0186] When the functions are implemented in the form of a software
functional unit and sold or used as an independent product, the
functions may be stored in a computer-readable storage medium.
Based on such an understanding, the solutions of the embodiments
essentially, or the part contributing to the prior art, or some of
the solutions may be implemented in a form of a software product.
The software product is stored in a storage medium and includes
several instructions for instructing a computer device (which may
be a personal computer, a server, or a network device) to perform
all or some of the steps of the methods described in the
embodiments. The foregoing storage medium includes: any medium that
can store program code, such as a USB flash drive, a removable hard
disk, a read-only memory (ROM), a random access memory (RAM), a
magnetic disk, or an optical disc.
[0187] The foregoing descriptions are merely specific
implementations of the embodiments and are non-limiting.
* * * * *