CN111654350A - Method for detecting frequency deviation of communication transmission network element equipment - Google Patents
Method for detecting frequency deviation of communication transmission network element equipment Download PDFInfo
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- H04J3/0617—Systems characterised by the synchronising information used the synchronising signal being characterised by the frequency or phase
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- H—ELECTRICITY
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- H04J3/16—Time-division multiplex systems in which the time allocation to individual channels within a transmission cycle is variable, e.g. to accommodate varying complexity of signals, to vary number of channels transmitted
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Abstract
The invention discloses a method for detecting frequency deviation of network element equipment of a communication transmission network, which can calculate the measurement interval time according to the time of sending messages twice and the time of receiving the messages twice in a PTP (precision time protocol), and can quickly detect the frequency deviation between a master device and a slave device according to the corresponding relation between the relative frequency deviation of the master device and the slave device and the measurement interval time, wherein the precision reaches ppb order of magnitude or above. And, when the frequency deviation exceeds a threshold, an alarm signal may be generated. According to the method for detecting the frequency deviation of the communication transmission network element equipment, provided by the invention, the master equipment can be applied to the communication transmission network SPN/PTN equipment, the slave equipment can be applied to the communication transmission network SPN/PTN equipment which does not adjust the equipment time in the measurement interval time, and an instrument or a base station connected with the SPN/PTN equipment.
Description
Technical Field
The invention relates to the technical field of communication time-frequency synchronization, in particular to a method for detecting frequency deviation of network element equipment of a communication transmission network.
Background
In order to ensure the normal operation of the digital communication transmission network, the synchronization of the whole network must be realized, that is, all network elements of the whole network are ensured to have the same frequency accuracy. Each telecom operator is provided with a synchronous network which consists of synchronous network node equipment and a synchronous timing link. The synchronous network node equipment is provided with a primary reference clock, a secondary node clock and a tertiary node clock, and synchronous timing signals of the node clocks are transmitted by the communication transmission network. According to the requirements of international standard ITU-T G.811, the frequency accuracy of the primary reference clock is superior to 1E-11, so that whether a high-precision clock signal can be smoothly transmitted to the end of a network or not is lack of an effective online real-time monitoring means at present.
In a traditional digital communication transport network, a timing link is carried by Synchronous Digital Hierarchy (SDH) equipment, the SDH system does not have a high-precision (ppb-level) frequency deviation (frequency deviation for short) performance monitoring mechanism, and only when the frequency deviation of upstream equipment exceeds the pulling range (± 4.6ppm) of the SDH system, the SDH system reports a frequency deviation out-of-limit alarm, and most manufacturers make better traction range indexes, the equipment pulling range is far greater than 4.6ppm, such as 8ppm, that is, when the frequency deviation of the upstream network element equipment is greater than or equal to 8ppm, the downstream network element equipment alarms. The frequency offset detection threshold range of the latest Sliced Packet Network (SPN) system can be set, and is generally 1ppm-9.2 ppm. In an SDH system, a Packet Transport Network (PTN) system, or an SPN system, the frequency offset detection threshold far exceeds the frequency offset requirement of the service (e.g., radio access Network) carried by the system. For example, in Global System for Mobile Communications (GSM), Long Term Evolution (LTE) systems, 5G base stations, etc., the radio frequency offset of these systems is required to be better than ± 50ppb, and the requirement of the wired input port (interface connected to the transmission network) is required to be better than 16 ppb. The existing carrying networks such as digital communication transmission networks and the like do not have the online real-time detection means of high-precision frequency deviation, so that the synchronous performance of the communication transmission network is difficult to effectively ensure the application of a service system.
In summary, the frequency offset detection accuracy of the existing digital communication transport network and packet transport network is in the ppm order, and generally does not reach the ppb level accuracy.
Disclosure of Invention
In view of the above, the present invention provides a method for detecting a frequency deviation of a network element device of a communications transport network, which is used to detect a synchronization performance, especially a frequency deviation, of the communications transport network, and evaluate whether the synchronization performance of the communications transport network, especially a service network such as a wireless network carried thereon, can meet a requirement.
The invention provides a method for detecting frequency deviation of network element equipment of a communication transmission network, which comprises the following steps:
s1: recording an upstream network element device of a communication transmission network as a master device running a PTP protocol, and recording a downstream network element device of the communication transmission network, or a test instrument connected with the master device, or a wireless base station connected with the master device as a slave device running the PTP protocol;
s2: acquiring the time when the master device sends a 0 th Sync message, acquiring the time when the master device sends an nth Sync message after a first preset time interval, and subtracting the time when the master device sends the 0 th Sync message from the time when the master device sends the nth Sync message to obtain a first measurement interval time; acquiring the time when the slave device receives the corresponding 0 th Sync message and the time when the slave device receives the corresponding nth Sync message, and subtracting the time when the slave device receives the 0 th Sync message from the time when the slave device receives the nth Sync message to obtain second measurement interval time;
s3: acquiring the time when the slave device sends the 0 th Daley _ Req message, acquiring the time when the slave device sends the mth Daley _ Req message after a second preset time interval, and subtracting the time when the slave device sends the 0 th Daley _ Req message from the time when the slave device sends the mth Daley _ Req message to obtain a third measurement interval time; acquiring the time when the master device receives the corresponding 0 th Daley _ Req message and the time when the master device receives the corresponding mth Daley _ Req message, and subtracting the time when the master device receives the 0 th Daley _ Req message from the time when the master device receives the mth Daley _ Req message to obtain a fourth measurement interval time;
s4: obtaining a relative frequency deviation value of the clock frequency of the master device and the clock frequency of the slave device according to a corresponding relation between a relative frequency deviation of the frequency of sending the Sync message by the master device relative to the frequency of receiving the Sync message by the slave device and the first measurement interval time and the second measurement interval time, or according to a corresponding relation between a relative frequency deviation of the frequency of receiving the Daley _ Req message by the master device relative to the frequency of sending the Daley _ Req message by the slave device and the third measurement interval time and the fourth measurement interval time;
s5: and judging the frequency synchronization performance of the communication transmission network according to the obtained relative frequency deviation value of the clock frequency of the master equipment and the clock frequency of the slave equipment.
In a possible implementation manner, in the method for detecting a frequency deviation of a network element device in a communications transport network provided by the present invention, in step S4, obtaining a relative frequency deviation value between a clock frequency of a master device and a clock frequency of a slave device according to a corresponding relationship between a relative frequency deviation of a frequency of sending a Sync message by the master device relative to a frequency of receiving a Sync message by the slave device and the first measurement interval time and the second measurement interval time, specifically includes:
the relative frequency deviation of the clock frequency of the master device relative to the clock frequency of the slave device is equal to the relative frequency deviation of the frequency of sending the Sync message by the master device relative to the frequency of receiving the Sync message by the slave device, and the relative frequency deviation of the frequency of sending the Sync message by the master device relative to the frequency of receiving the Sync message by the slave device is equal to the ratio of the difference between the second measurement interval time and the first measurement interval time to the first measurement interval time.
In a possible implementation manner, in the method for detecting a frequency deviation of a network element device in a communications transport network provided by the present invention, in step S4, obtaining a relative frequency deviation value between a clock frequency of a master device and a clock frequency of a slave device according to a corresponding relationship between a relative frequency deviation of a frequency of receiving a Daley _ Req packet by the master device relative to a frequency of sending a Daley _ Req packet by the slave device, and the third measurement interval time and the fourth measurement interval time, specifically includes:
the relative frequency deviation of the clock frequency of the master device relative to the clock frequency of the slave device is equal to the relative frequency deviation of the frequency of receiving the Daley _ Req messages by the master device relative to the frequency of sending the Daley _ Req messages by the slave device, and the relative frequency deviation of the frequency of receiving the Daley _ Req messages by the master device relative to the frequency of sending the Daley _ Req messages by the slave device is equal to the ratio of the difference between the third measurement interval time and the fourth measurement interval time.
In a possible implementation manner, in the method for detecting a frequency deviation of a network element device of a communications transport network provided by the present invention, the first preset time interval is greater than or equal to 20 s.
In a possible implementation manner, in the method for detecting a frequency deviation of a network element device of a communications transport network provided by the present invention, the second preset time interval is greater than or equal to 20 s.
In a possible implementation manner, in the method for detecting a frequency deviation of a network element device of a communications transport network provided by the present invention, after the step S5 is executed, and the frequency synchronization performance of the communications transport network is determined according to the obtained clock frequency deviation value of the master device and the slave device, the method further includes the following steps:
s6: setting a frequency deviation monitoring threshold value according to the synchronous performance requirement of a service network carried by a communication transmission network; and when the obtained relative frequency deviation value of the clock frequency of the master equipment and the clock frequency of the slave equipment exceeds a set frequency deviation monitoring threshold value, sending an alarm signal.
The method for detecting the frequency deviation of the communication transmission network element equipment can calculate the measurement interval time according to the time of sending the message twice and the time of receiving the message twice in the PTP protocol, can quickly detect the frequency deviation between the master equipment and the slave equipment according to the corresponding relation between the relative frequency deviation of the master equipment and the slave equipment and the measurement interval time, can reach the ppb order of magnitude or above, is closely related to the measurement interval time, and can completely meet the requirement of the radio access network on the detection precision of the frequency deviation of 16 ppb. And, when the frequency deviation exceeds a prescribed threshold, an alarm signal may be automatically generated. According to the method for detecting the frequency deviation of the communication transmission network element equipment, provided by the invention, the master equipment can be applied to the communication transmission network SPN/PTN equipment, the slave equipment can be applied to the communication transmission network SPN/PTN equipment which does not adjust the equipment time in the measurement interval time, and equipment such as an instrument or a base station connected with the SPN/PTN equipment.
Drawings
Fig. 1 is a flowchart of a method for detecting a frequency offset of a network element device in a communications transport network according to the present invention;
FIG. 2 shows the utilization of t in the PTP protocol1、t2Calculating a schematic of a frequency deviation of a master device relative to a slave device;
FIG. 3 shows the utilization of t in the PTP protocol3、t4Calculating a schematic of a frequency deviation of a master device relative to a slave device;
fig. 4 is a second flowchart of a method for detecting a frequency offset of a network element device of a communications transport network according to the present invention;
FIG. 5 is a schematic diagram of a connection between a master device and a slave device;
FIG. 6 is a screen shot of group 1 timestamp data captured by a slave device when the slave device is frequency-homologous to a master device.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only examples and are not intended to limit the present invention.
The method for detecting the frequency deviation of the network element equipment of the communication transmission network, as shown in fig. 1, comprises the following steps:
s1: recording an upstream network element device of a communication transmission network as a master device running a PTP protocol, and recording a downstream network element device of the communication transmission network, or a test instrument connected with the master device, or a wireless base station connected with the master device as a slave device running the PTP protocol;
specifically, the slave device is not limited to a downstream network element device of the communication transport network, but may be any device in the communication network that operates the PTP protocol, such as a wireless base station or a test meter;
s2: acquiring the time when the master device sends a 0 th Sync message, acquiring the time when the master device sends an nth Sync message after a first preset time interval, and subtracting the time when the master device sends the 0 th Sync message from the time when the master device sends the nth Sync message to obtain a first measurement interval time; acquiring the time when the slave equipment receives the corresponding 0 th Sync message and the time when the slave equipment receives the corresponding nth Sync message, and subtracting the time when the slave equipment receives the 0 th Sync message from the time when the slave equipment receives the nth Sync message to obtain second measurement interval time;
s3: acquiring the time when the slave equipment sends the 0 th Daley _ Req message, acquiring the time when the slave equipment sends the mth Daley _ Req message after a second preset time interval, and subtracting the time when the slave equipment sends the 0 th Daley _ Req message from the time when the slave equipment sends the mth Daley _ Req message to obtain a third measurement interval time; acquiring the time when the master device receives the corresponding 0 th Daley _ Req message and the time when the master device receives the corresponding mth Daley _ Req message, and subtracting the time when the master device receives the 0 th Daley _ Req message from the time when the master device receives the mth Daley _ Req message to obtain a fourth measurement interval time;
s4: obtaining a relative frequency deviation value of a clock frequency of the master device and a clock frequency of the slave device according to a corresponding relation between a relative frequency deviation of a frequency of sending the Sync message by the master device relative to a frequency of receiving the Sync message by the slave device and a first measurement interval time and a second measurement interval time, or according to a corresponding relation between a relative frequency deviation of a frequency of receiving a Daley _ Req message by the master device relative to a frequency of sending the Daley _ Req message by the slave device and a third measurement interval time and a fourth measurement interval time;
s5: and judging the frequency synchronization performance of the communication transmission network according to the obtained relative frequency deviation value of the clock frequency of the master equipment and the clock frequency of the slave equipment.
In a specific implementation, in the method for detecting a frequency deviation of a network element device of a communications transport network provided by the present invention, a port of an upstream network element device of the communications transport network may be set as a master port, a port corresponding to a downstream network element device of the communications transport network, or a test instrument connected to the master device, or a radio base station connected to the master device is set as a slave port, and a PTP protocol is run. Specifically, both the master device and the slave device support the 1588v2 PTP protocol.
The following describes in detail t in the PTP protocol1、t2、t3、t4Four time stamps are used to calculate the frequency offset between the master and slave devices.
Setting the frequency of sending Sync message by the master device as f1The frequency of receiving Sync message from the slave device is f2. As shown in FIG. 2, the time when the primary device sends the 0 th Sync message is t10Every one Sync message sending period TmThe time of sending the 1 st Sync message is t11Two periods T of sending Sync messages at intervalsmThe time of sending the 2 nd Sync message is t12The time for sending the n-2 th Sync message after the interval of n-2 Sync message periods is t1(n-2), the moment of sending the n-1 Sync message after the interval of n-1 Sync message periods is t1(n-1), the moment of sending the nth Sync message after the interval of n Sync message periods is t1n. The moment when the slave device receives the 0 th Sync message is t20At intervals of one received Sync message period TsThe moment of receiving the 1 st Sync message is t21The time for receiving the n-2 th Sync message after the interval of n-2 Sync message periods is t2(n-2), the time of receiving the n-1 Sync message after the interval of n-1 Sync message periods is t2(n-1)The time of receiving the nth Sync message after the interval of n Sync message receiving periods is t2n. Frequency f of sending Sync message by master equipment1And sending Sync message period TmFrequency f of receiving Sync message from equipment2And receiving Sync message period TsThe relationship of (a) to (b) is as follows:
f1＝1/Tm＝1/(t11-t10) (1)
f2＝1/Ts＝1/(t21-t20) (2)
from equations (1) and (2) we can obtain:
f1/f2＝(t21-t20)/(t11-t10) (3)
from equation (3) we can obtain:
f1/f2＝n*(t21-t20)/n*(t11-t10)
＝((t2n-t2(n-1))+(t2(n-1)-t2(n-2))+…+(t21-t20))/((t1n-t1(n-1))+(t1(n-1)-t1(n-2))+…+(t11-t10))
＝(t2n-t20)/(t1n-t10) (4)
thus, t by PTP protocol1、t2Calculating the frequency f of sending Sync message by the main equipment1Frequency f relative to the reception of Sync messages from a slave device2The relative frequency deviation of (a) is:
(f1/f2)-1＝((t2n-t20)/(t1n-t10))-1 (5)
similarly, as shown in fig. 3, the time when the slave device sends the 0 th Daley _ Req message is t30The time for sending the 1 st Daley _ Req message after one Daley _ Req message sending period is t31The time for sending the 2 nd Daley _ Req message after two Daley _ Req message sending periods is t32The time for sending the (n-2) th Daley _ Req message after the interval of n-2 Daley _ Req message periods is t3(n-2)The time for sending the (n-1) th Daley _ Req message after n-1 Daley _ Req message periods is t3(n-1)The time for sending the nth Daley _ Req message after n Daley _ Req message periods is t3n. The time when the master device receives the 0 th Daley _ Req message is t40The time when the 1 st Daley _ Req message is received after one Daley _ Req message receiving period is t41The time for receiving the 2 nd Daley _ Req message after two cycles of receiving Daley _ Req messages is t42The time for receiving the (n-2) th Daley _ Req message after the interval of n-2 Daley _ Req message periods is t4(n-2)The time for receiving the (n-1) th Daley _ Req message after the interval of n-1 Daley _ Req message periods is t4(n-1)The time for receiving the nth Daley _ Req message after n cycles of receiving Daley _ Req messages is t4n. By the same token, t through the PTP protocol can be deduced3、t4Frequency f of receiving Daley _ Req message by computing master equipment4And frequency f of sending Daley _ Req message from the equipment3The relative frequency deviation of (a) is:
(f4/f3)-1＝((t3m-t30)/(t4m-t40))-1 (6)
assume that the clock frequency of the master device is fmThe clock frequency of the slave device is fsAnd they have the same nominal frequency. Due to f1And f4Are all clocked by the master device, so that f1And f4Clock frequency f of both master devicesmDiffer by a multiple of a constant, and f1And f4Clock frequency f of both master devicesmThe frequency accuracy of the frequency is the same; in the same way, since f2And f3Are all controlled by the slave clock, so f2And f3Clock frequency f of the slave devicessDiffer by a multiple of a constant, and f2And f3Clock frequency f of the slave devicessThe frequency accuracy of (2) is the same. Thus, it is possible to obtain:
fm/fs＝f1/f2＝f4/f3(7)
from equation (7) we can obtain:
(fm/fs)-1＝(f1/f2)-1＝(f4/f3)-1 (8)
in summary, when step S2 in the method for detecting a frequency offset of a network element device in a communications transport network according to the present invention is executed, the time t when the master device sends the 0 th Sync message is obtained10Acquiring the time t when the master equipment sends the nth Sync message after the first preset time interval1nThe time t when the master device sends the nth Sync message1nMinus the time t when the master device sends the 0 th Sync message10Obtaining a first measurement interval time (t)1n-t10) (ii) a ObtainThe time t when the slave device receives the corresponding 0 th Sync message is taken20And the time t of receiving the corresponding n-th Sync message2nTime t of receiving n-th Sync message from slave device2nMinus the time t of receiving the 0 th Sync message from the slave device20Obtaining a second measurement interval time (t)2n-t20). In step S4 of the method for detecting frequency deviation of a network element device in a communication transmission network according to the present invention, the first measurement interval (t) is determined according to the relative frequency deviation of the frequency of the Sync message sent by the master device relative to the frequency of the Sync message received by the slave device1n-t10) Second measurement interval time (t)2n-t20) When the relative frequency deviation value of the clock frequency of the master device and the clock frequency of the slave device is obtained, the relative frequency deviation of the clock frequency of the master device relative to the clock frequency of the slave device is equal to the relative frequency deviation of the frequency of sending the Sync message by the master device relative to the frequency of receiving the Sync message by the slave device, and the relative frequency deviation of the frequency of sending the Sync message by the master device relative to the frequency of receiving the Sync message by the slave device is equal to the second measurement interval time (t)2n-t20) With a first measurement interval time (t)1n-t10) After a difference with a first measurement interval (t)1n-t10) The ratio of (a) to (b) may be specifically realized by the following means:
the relative frequency deviation of the frequency of sending the Sync message by the master device relative to the frequency of receiving the Sync message by the slave device is as follows:
(fm/fs)-1＝((t2n-t20)/(t1n-t10))-1 (9)。
in a specific implementation, in the method for detecting a frequency deviation of a network element device of a communications transport network provided by the present invention, when the measurement accuracy requirement is greater than or equal to 1E-9, the first preset time interval may be set to be greater than or equal to 20s, and when the measurement accuracy requirement is greater than or equal to 1E-11, the first preset time interval may be set to be greater than or equal to 1200 s.
Similarly, the steps in the method for detecting the frequency deviation of the network element equipment of the communication transmission network provided by the invention are executedS3, obtaining the time t when the slave equipment sends the 0 th Daley _ Req message30Acquiring the time t when the slave device sends the mth Daley _ Req message after a second preset time interval3mTime t when slave device sends mth Daley _ Req message3mMinus the time t when the slave device sends the 0 th Daley _ Req message30Obtaining a third measurement interval time (t)3m-t30) (ii) a Acquiring the time t when the main equipment receives the corresponding 0 Daley _ Req message40And time t of receiving the corresponding mth Daley _ Req message4mThe time t when the master device receives the mth Daley _ Req packet4mMinus the time t when the master device receives the 0 th Daley _ Req message40Obtaining a fourth measurement interval time (t)4m-t40). In step S4 of the method for detecting frequency deviation of a network element device in a communications transport network according to the present invention, a third measurement interval (t) is determined according to a relative frequency deviation of a frequency of receiving a Daley _ Req message by a master device with respect to a frequency of sending the Daley _ Req message by a slave device3m-t30) Fourth measurement interval time (t)4m-t40) When the clock frequency deviation value of the master device and the slave device is obtained, the relative frequency deviation of the clock frequency of the master device relative to the clock frequency of the slave device is equal to the relative frequency deviation of the frequency of receiving the Daley _ Req message by the master device relative to the frequency of sending the Daley _ Req message by the slave device, and the relative frequency deviation of the frequency of receiving the Daley _ Req message by the master device relative to the frequency of sending the Daley _ Req message by the slave device is equal to the third measurement interval time (t)3m-t30) With a fourth measurement interval time (t)4m-t40) After the difference is made, the fourth measurement interval (t)4m-t40) The ratio of (a) to (b) may be specifically realized by the following means:
the relative frequency deviation of the frequency of receiving the Daley _ Req message by the master device relative to the frequency of sending the Daley _ Req message by the slave device is as follows:
(fm/fs)-1＝((t3m-t30)/(t4m-t40))-1 (10)。
in a specific implementation, in the method for detecting a frequency deviation of a network element device of a communications transport network provided by the present invention, when the measurement accuracy requirement is greater than or equal to 1E-9, the second preset time interval may be set to be greater than or equal to 20s, and when the measurement accuracy requirement is greater than or equal to 1E-11, the second preset time interval may be set to be greater than or equal to 1200 s.
T in PTP message (including Sync message and Daley _ Req message) adopting one step1、t2、t3、t4The precision of (A) is the order of magnitude of plus or minus N ns (N is less than or equal to 10); sync message t adopting two step mode1、t2The time precision is better than +/-1 ns order of magnitude, t3、t4Is still + -Nns (N.ltoreq.10), so the accuracy of the relative frequency deviation of the master clock and the slave clock depends on the measurement interval. T in one step mode1、t2、t3、t4Calculating, when the measurement interval time is 1s, the accuracy of calculating the frequency deviation is better than N × E-9; when the measurement interval time is 20s, the accuracy of calculating the frequency deviation is better than (0.5N) E-10; when the measurement interval time is 20min, the accuracy of calculating the frequency deviation is better than (8.33N) E-13; when the measurement interval time is 24h, the accuracy of calculating the frequency deviation is better than (1.16N) × E-14. T using two step approach1、t2The accuracy of the calculated frequency offset is the same as above except that N is 1.
In specific implementation, in the method for detecting a frequency deviation of a network element device of a communications transport network provided by the present invention, after the step S5 is executed, and the frequency synchronization performance of the communications transport network is determined according to the obtained clock frequency deviation value of the master device and the slave device, as shown in fig. 4, the method may further include the following steps:
s6: setting a frequency deviation monitoring threshold value according to the synchronous performance requirement of a service network carried by a communication transmission network; and when the obtained clock frequency deviation value of the master equipment and the slave equipment exceeds a set frequency deviation monitoring threshold value, sending an alarm signal. For example, when the detected frequency deviation value is more than or equal to 1ppb, a prompt alarm is reported; when the detected frequency deviation value is more than or equal to 16ppb, reporting a main alarm; and when the detected frequency deviation value is more than or equal to 50ppb, reporting a serious alarm. Specifically, the frequency deviation monitoring threshold may be set according to the wireless network synchronization performance requirement, for example, 16ppb meeting the wireless base station wired input interface synchronization requirement.
In the following, t in the PTP protocol1、t2、t3、t4The frequency deviation between the upstream network element equipment and the downstream network element equipment of the communication transmission network, or between the upstream network element equipment of the communication transmission network and a test instrument connected with the upstream network element equipment, or between the upstream network element equipment of the communication transmission network and a wireless base station connected with the upstream network element equipment is calculated. The calculation is carried out in two scenes, wherein the first scene is that the frequency of the slave device is the same as that of the master device, and the second scene is that the frequency of the slave device is different from that of the master device.
Scene one: the slave device is frequency-homologous to the master device.
The connection between the master and the slave is shown in fig. 5. The master device is a master device running a PTP protocol, the slave device is a slave device running the PTP protocol, the slave device is replaced by a test instrument, and the slave device does not adjust the time of the slave device according to the time offset (offset) calculated by the PTP protocol. Firstly, a PTP (precision time protocol) is operated between a master device and a slave device; secondly, the slave device captures the time stamps t of the PTP messages 6 times in sequence1、t2、t3、t4(i.e., 1-6 sets of data in table 1), wherein the time stamp data screen capture of the 1 st set of data is shown in fig. 6, and the six sets of data represent data captured at different measurement intervals, which are different from several seconds, several tens of seconds, several thousands of seconds, and several tens of thousands of seconds. In the scene, the synchronous message adopts a two step mode.
TABLE 1 PTP message timestamp information captured 6 times when the slave device and the master device are frequency-homologous
Randomly selecting t of two groups of data from 1-6 groups of data in Table 11、t2Calculating the frequency deviation of the master device relative to the slave device by using the formula (9), wherein the calculation result is shown in table 2; randomly selecting t of two groups of data from 1-6 groups of data in Table 13、t4The frequency deviation of the master device with respect to the slave device is calculated using equation (10), and the calculation results are shown in table 3.
TABLE 2 frequency offset of master to slave calculated with t1, t2 when slave is frequency-homologous to master
TABLE 3 frequency offset of Master to Slave calculated with t3, t4 while Slave is frequency-homologous to Master
As can be seen from table 2, when the slave device is frequency-homologous to the master device, the frequency deviation calculated by using t1 and t2 is substantially zero, which is consistent with the actual situation. The calculated frequency deviation between the group 2 and the group 6 is-3.82E-12, which is mainly caused by the accuracy of t1 and t2 being 1ns, and an error of 1ns is generated in the measurement interval 2618s, and the deviation is-3.82E-12.
As can be seen from table 3, when the slave device has the same frequency as the master device, the frequency deviation calculated by using t3 and t4 is also small, which is consistent with the actual situation. The frequency deviation calculated for the group 3 and group 4 data is 0, mainly due to the measurement interval being too short (about 2s), the first measurement interval being the same as the second measurement interval in the order of ns. The measurement precision of the latter three groups of data is gradually improved along with the increase of the measurement interval time, and the measured frequency deviation is more accurate. In the case of measurement intervals of one thousand seconds, two thousand seconds and seventy thousand seconds, the measurement accuracy can reach NxE-12, (0.5N) E-12 and (0.71N) E-14, respectively. N is theoretically equal to 4, so the above data is substantially accurate and the results of the combined calculations of group 1 and group 6 data are more accurate.
And in the second scenario, the slave device and the master device have different frequencies.
The connection between the master and the slave is shown in fig. 5. The master device running the PTP protocolThe master device and the slave device are slave devices running PTP protocol, the slave device is replaced by a test instrument, and the slave device does not adjust the time of the slave device according to the time offset (offset) calculated by the PTP protocol. Firstly, a PTP (precision time protocol) is operated between a master device and a slave device; secondly, the slave device captures the time stamps t of the PTP messages 3 times in sequence1、t2、t3、t4(i.e., 7-9 sets of data in Table 4). These 3 sets of data represent t captured at different measurement intervals1、t2、t3、t4Time stamps, measurement intervals vary from a few seconds to tens of seconds. In the scene, the synchronous message adopts a two step mode.
TABLE 4 PTP message timestamp information captured 3 times when the slave device and the master device have different frequencies
Randomly selecting t of two groups of data from 7-9 groups of data in Table 41、t2Calculating the frequency deviation of the master device relative to the slave device by using the formula (9), and the calculation result is shown in table 5; randomly selecting t of two groups of data from 7-9 groups of data in Table 43、t4The frequency deviation of the master device with respect to the slave device is calculated using equation (10), and the calculation results are shown in table 6.
TABLE 5 frequency offset of master to slave calculated using t1, t2 when slave and master frequencies are different
TABLE 6 frequency offset of master device with respect to slave device calculated using t3, t4 when slave device and master device are at different frequencies
As can be seen from Table 5, when the slave device and the master device are different in frequency, the frequency deviation calculated using t1 and t2 is on the order of 1E-11. The measurement intervals are 94s and 95s respectively, the measurement accuracy is 1.06E-11 and 1.05E-11 respectively, and the data is three times better than that in the table 5, which shows that the data is credible. The frequency deviation calculated for the 8 th and 9 th group of data is 0, mainly due to the measurement interval being too short (about 1s), the first measurement interval being the same as the second measurement interval in the order of ns.
It can be seen from table 6 that the frequency deviation calculated using t3, t4 is also on the order of 1E-11 when the slave device and master device frequencies are different. The measurement interval time is 94s and 95s respectively, the measurement accuracy is N × E-11 orders of magnitude, and the calculation data and the measurement accuracy are in one level, so that the data reliability is low, and the measurement interval time needs to be prolonged. The frequency deviation calculated in the 8 th and 9 th groups of data was 8.00E-9, which is mainly caused by Nns error between the first measurement interval and the second measurement interval due to too short measurement interval (about 1s), the test accuracy was N × E-9, and the calculation result was not reliable.
In summary, in order to achieve the detection threshold of 16ppb meeting the requirement of the mobile base station, the measurement interval time is required to be greater than or equal to 20s, so that the measurement accuracy of (0.5N) E-10 can be ensured to be achieved and is far better than the detection threshold requirement of 16 ppb; in order to meet the accuracy requirement for detecting the communications transport network 1E-11, the measurement interval time needs to be greater than or equal to 20 min. And preferentially selects t1 and t2 in the PTP protocol for calculation.
The method for detecting the frequency deviation of the communication transmission network element equipment can calculate the measurement interval time according to the time of sending the message twice and the time of receiving the message twice in the PTP protocol, can quickly detect the frequency deviation between the master equipment and the slave equipment according to the corresponding relation between the relative frequency deviation of the master equipment and the slave equipment and the measurement interval time, selects the measurement interval time of more than 20s, and can ensure that the precision of the measured frequency deviation can reach (0.5N) E-10 order of magnitude and can completely meet the requirement of the frequency deviation detection precision of 16ppb of a wireless access network. The measurement interval time of 20min and more is selected, the accuracy of measuring the frequency deviation can reach the order of (8.33N) E-13, and the synchronization performance of the transmission network can be detected. An alarm signal may be automatically generated when the frequency deviation exceeds a specified threshold. If the measurement interval time is increased, the measurement accuracy can be further improved. According to the method for detecting the frequency deviation of the communication transmission network element equipment, provided by the invention, the master equipment can be applied to the communication transmission network SPN/PTN equipment, the slave equipment can be applied to the communication transmission network SPN/PTN equipment which does not adjust the equipment time in the measurement interval time, and equipment such as an instrument or a base station connected with the SPN/PTN equipment. If the slave equipment adopts a high-precision frequency reference, the detection precision is higher.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (6)
1. A method for detecting a frequency offset of a network element device of a communications transport network, comprising the steps of:
s1: recording an upstream network element device of a communication transmission network as a master device running a PTP protocol, and recording a downstream network element device of the communication transmission network, or a test instrument connected with the master device, or a wireless base station connected with the master device as a slave device running the PTP protocol;
s2: acquiring the time when the master device sends a 0 th Sync message, acquiring the time when the master device sends an nth Sync message after a first preset time interval, and subtracting the time when the master device sends the 0 th Sync message from the time when the master device sends the nth Sync message to obtain a first measurement interval time; acquiring the time when the slave device receives the corresponding 0 th Sync message and the time when the slave device receives the corresponding nth Sync message, and subtracting the time when the slave device receives the 0 th Sync message from the time when the slave device receives the nth Sync message to obtain second measurement interval time;
s3: acquiring the time when the slave device sends the 0 th Daley _ Req message, acquiring the time when the slave device sends the mth Daley _ Req message after a second preset time interval, and subtracting the time when the slave device sends the 0 th Daley _ Req message from the time when the slave device sends the mth Daley _ Req message to obtain a third measurement interval time; acquiring the time when the master device receives the corresponding 0 th Daley _ Req message and the time when the master device receives the corresponding mth Daley _ Req message, and subtracting the time when the master device receives the 0 th Daley _ Req message from the time when the master device receives the mth Daley _ Req message to obtain a fourth measurement interval time;
s4: obtaining a relative frequency deviation value of the clock frequency of the master device and the clock frequency of the slave device according to a corresponding relation between a relative frequency deviation of the frequency of sending the Sync message by the master device relative to the frequency of receiving the Sync message by the slave device and the first measurement interval time and the second measurement interval time, or according to a corresponding relation between a relative frequency deviation of the frequency of receiving the Daley _ Req message by the master device relative to the frequency of sending the Daley _ Req message by the slave device and the third measurement interval time and the fourth measurement interval time;
s5: and judging the frequency synchronization performance of the communication transmission network according to the obtained relative frequency deviation value of the clock frequency of the master equipment and the clock frequency of the slave equipment.
2. The method according to claim 1, wherein in step S4, obtaining the relative frequency deviation value between the clock frequency of the master device and the clock frequency of the slave device according to the corresponding relationship between the first measurement interval and the second measurement interval and the relative frequency deviation between the frequency of sending Sync messages by the master device and the frequency of receiving Sync messages by the slave device, specifically comprises:
the relative frequency deviation of the clock frequency of the master device relative to the clock frequency of the slave device is equal to the relative frequency deviation of the frequency of sending the Sync message by the master device relative to the frequency of receiving the Sync message by the slave device, and the relative frequency deviation of the frequency of sending the Sync message by the master device relative to the frequency of receiving the Sync message by the slave device is equal to the ratio of the difference between the second measurement interval time and the first measurement interval time to the first measurement interval time.
3. The method according to claim 1, wherein in step S4, obtaining a relative frequency deviation value between the clock frequency of the master device and the clock frequency of the slave device according to a corresponding relationship between a relative frequency deviation between the frequency of receiving Daley _ Req packets by the master device and the frequency of sending Daley _ Req packets by the slave device, the third measurement interval time, and the fourth measurement interval time, specifically comprises:
the relative frequency deviation of the clock frequency of the master device relative to the clock frequency of the slave device is equal to the relative frequency deviation of the frequency of receiving the Daley _ Req messages by the master device relative to the frequency of sending the Daley _ Req messages by the slave device, and the relative frequency deviation of the frequency of receiving the Daley _ Req messages by the master device relative to the frequency of sending the Daley _ Req messages by the slave device is equal to the ratio of the difference between the third measurement interval time and the fourth measurement interval time.
4. A method of detecting a frequency deviation in a network element device of a communications transport network as claimed in claim 1, characterised in that said first predetermined time interval is greater than or equal to 20 s.
5. A method of detecting a frequency deviation in a network element device of a communications transport network as claimed in claim 1, characterised in that said second predetermined time interval is greater than or equal to 20 s.
6. The method for detecting the frequency deviation of the network element equipment of the communication transport network according to any one of claims 1 to 5, wherein after the step S5 is executed, the method further comprises the following steps after the frequency synchronization performance of the communication transport network is judged according to the obtained relative frequency deviation value of the clock frequency of the master equipment and the clock frequency of the slave equipment:
s6: setting a frequency deviation monitoring threshold value according to the synchronous performance requirement of a service network carried by a communication transmission network; and when the obtained relative frequency deviation value of the clock frequency of the master equipment and the clock frequency of the slave equipment exceeds a set frequency deviation monitoring threshold value, sending an alarm signal.
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Application publication date: 20200911 |