KR101665924B1 - Frequency offset estimation system using network time protocol time offset - Google Patents
Frequency offset estimation system using network time protocol time offset Download PDFInfo
- Publication number
- KR101665924B1 KR101665924B1 KR1020150109999A KR20150109999A KR101665924B1 KR 101665924 B1 KR101665924 B1 KR 101665924B1 KR 1020150109999 A KR1020150109999 A KR 1020150109999A KR 20150109999 A KR20150109999 A KR 20150109999A KR 101665924 B1 KR101665924 B1 KR 101665924B1
- Authority
- KR
- South Korea
- Prior art keywords
- time
- ntp
- foe
- err
- offset
- Prior art date
Links
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L7/00—Arrangements for synchronising receiver with transmitter
- H04L7/0016—Arrangements for synchronising receiver with transmitter correction of synchronization errors
- H04L7/0033—Correction by delay
- H04L7/0037—Delay of clock signal
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
- H04L69/28—Timers or timing mechanisms used in protocols
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L7/00—Arrangements for synchronising receiver with transmitter
- H04L7/0008—Synchronisation information channels, e.g. clock distribution lines
Abstract
Description
The present invention relates to a network time protocol (NTP) time offset which can precisely estimate a frequency error by excluding an invalid value for a time offset value changing for each packet in an NTP system and judging heterogeneity between the estimated frequency errors A frequency error estimation system using the same.
Network time protocol (NTP) is a protocol used to synchronize the clock time of systems connected to the network. Techniques for estimating and compensating for time offset or frequency error in an NTP system are known in a variety of background arts.
As a background to the present invention, there is a network time protocol precision timestamping service of Korean Patent Laid-Open No. 10-2009-0024170 A shown in FIG. This technique relates to a method and system for reducing the inaccuracy of receive and transmit timestamps generated by an NTP server, wherein the inaccuracy of receive timestamps is such that the incoming packets are not delayed by skipping the various software layers of the timestamping system And the inaccuracy of the transmission timestamps is removed by applying the future timestamps to the outgoing packets using the estimate of the transmission wait calculated by the atmospheric estimator filter, Recalculate and update the atmospheric estimates.
As another background of the present invention, there is a network link available bandwidth estimation method using the time stamp function of the Internet Control Message Protocol of Korean Patent Registration No. 10-0817798 B1 shown in FIG. 2. This technology relates to a method of sending a small size exploration packet using the time stamp function of the Internet Control Message Protocol (ICMP) and estimating the available bandwidth of the network link using the time information of the returned exploration packet. And an available bandwidth of an external network link connected to the network is easily estimated and monitored.
The present invention eliminates time offset values out of the allowable range with respect to a time offset value varying every packet in an NTP system, determines a heterogeneity between the estimated frequency errors, and calculates a final frequency error, And to provide a frequency error estimation system using a network time protocol (NTP) time offset capable of estimating an error.
The present invention is provided in an NTP client connected to an NTP server; A time offset estimation unit for obtaining a plurality of time offsets by using time stamps of the transmission / reception NTP packets; A median averaged filter for extracting valid time offset information from a plurality of time offset information provided from the time offset estimation unit, And a frequency offset estimating unit for estimating a frequency offset of the received signal. The present invention provides a frequency offset estimation system using NTP time offset as a solution to the problem.
According to the frequency offset estimation system using the NTP (network time protocol) time offset of the present invention, the time offset values outside the allowable range are excluded from the time offset values varying every packet in the NTP system to an invalid value, The present invention provides a technical effect of estimating a precise frequency error by calculating the final frequency error by determining the heterogeneity between the frequency errors.
FIG. 1 is a diagram illustrating a structure of a network time protocol precision time stamping service
FIG. 2 is a diagram illustrating a method for estimating a network link available bandwidth using a time stamp function of an Internet Control Message Protocol
FIG. 3 is a diagram illustrating a visual information exchange relationship of an NTP network
FIG. 4 is a diagram showing an example of the basic configuration of the present invention
FIG. 5 is a diagram illustrating an operation relationship according to the configuration of a frequency error estimation system using NTP (network time protocol) time offset of the present invention
FIG. 6 is a graph showing the application result of the median averaging filter of the present invention
7 is a graph showing a processing result of the frequency offset estimation unit
Synchronization of systems on the network requires time synchronization. Network time protocol (NTP) is a protocol used to synchronize the clock time of systems connected to the network. NTP uses coordinated universal time (UTC), which is provided through wireless or satellite systems, to synchronize the clock times of systems to below msec. However, since it is uneconomical to install a universal time receiver on all systems, it operates in such a manner that the receiver is installed only on the server designated by the visual server and the clock time of the networked systems is synchronized using NTP have.
The small cell transmits an NTP packet to the NTP server having the coordinated world time receiver even in a network using a small cell as a client that requires more precise synchronization than a normal NTP, The time offset can be determined and compensated. The accuracy of the clock frequency for communications such as WCDMA, TD-SCDMA, LTE-FDD and LTE-TDD depends on the wide area, the local area and the small cell, ppb]. However, since the packet delay between the client and the server is not constant, it is not easy to estimate the accurate time and frequency error (PDV).
The present invention provides a frequency error estimation system using a time offset that accurately estimates a frequency error using a time offset between a server and a client in NTP.
If there is a difference in clock frequency between the server and the client in the NTP system, the time offset changes every packet. Therefore, by analyzing the change of the time offset of each packet, the frequency offset can be estimated. If it is excluded as a non-value, the frequency error can be estimated more accurately. Further, by estimating the heterogeneity between the estimated frequency errors and calculating the final frequency error, a more precise frequency error can be estimated.
FIG. 3 shows the visual information exchange relationship of the NTP network. First, when the NTP client requests time information to the NTP server, the NTP client transmits the client time-stamped time T1 as a time stamp. The NTP server includes the time T2 of the NTP server at the moment of receiving the request of the NTP client and the time T3 of the current coordinated universal time (UTC) and the moment of transmission to the client as timestamps Respond to client requests. The client determines the delay time in the network by using the time T4 and the time T1, T2, and T3 at which the response of the NTP server is received, and sets the delay time in addition to the coordinated universal time (UTC) as the system time. The client may be configured to repeat the time synchronization of the system at a predetermined time interval (poll interval) or to request time information for the NTP server according to an arbitrary rule.
However, since the packet delay of the transmission / reception packets between the client and the server is not constant, it is difficult to accurately estimate the PDV (packet delay variance). Also, the time offset is changed every packet by the difference of the clock frequency between the server and the client.
The present invention estimates a frequency error by analyzing a change in a time offset of each NTP packet, excludes time offset values outside an allowable range with an invalid value to estimate a more accurate frequency error, (NTP) time offset for estimating a precise frequency error by calculating a final frequency error.
FIG. 4 shows one embodiment of the basic configuration of the present invention. The frequency offset estimation system using the NTP time offset of the present invention includes a time offset estimation unit 210 provided in the
FIG. 5 is a diagram illustrating an operation relationship according to the configuration of a frequency error estimation system using NTP (network time protocol) time offset of the present invention. The time offset estimating unit 210 of the present invention estimates the NTP packet transmission time T1 (i) from the
[ Equation One]
T_os (i) = 1/2 [{T2 (i) - T1 (i)} + {T3 (i) - T4 (i)}]; i = 1, 2, 3 ... , N_maf
T1 (i) = NTP packet transmission time of the client
T2 (i) = NTP packet reception time of the NTP server
T3 (i) = NTP response packet transmission time of the NTP server
T4 (i) = time at which the client receives the NTP response packet
The N_maf t_os (i) output from the time offset estimation unit 210 is provided as an input to the median averaging filter 220 and the median averaging filter 220 filters the input N_maf t_os (i) sort) and take intermediate M (M <N_maf) values. The median averaging filter 220 obtains a standard deviation sigma of M (M < N_maf) t_os (i) values, and judges that the standard deviation sigma is less than the time offset threshold TH_maf as reliable t_os And calculates and outputs an average value t_av (j) of these values and an average value T3_av (j) of T3 (i) at that time.
Of the N_maf t_os (i) values input from the median averaging filter 220, an excessively small or large t_os (i) value is caused by an instantaneous transmission / reception delay depending on the network state, and the frequency is low. When the time offset is estimated by reflecting these values, the fluctuation of the estimated value can be increased. Therefore, the N_maf t_os (i) values input from the median averaging filter 220 are sorted by size, (M < N_maf) < / RTI > Also, even if the median M (M < N_maf) values are taken from the N_maf t_os (i) values by the median averaging filter 220, t_os (i) values that are abnormally too small or too large may be distributed according to the network state have. Therefore, the median averaging filter 220 of the present invention determines the standard deviation sigma of M (M < N_maf) t_os (i) values and determines the reliable t_os (i) values if the obtained standard deviation sigma is smaller than the threshold value TH_maf And calculates and outputs an average value t_av (j) of these values and an average value T3_av (j) of T3 (i) at that time. At this time, the threshold TH_maf of the standard deviation? Is determined according to the state of the network to which the client and the server are connected and the required range of the applied network.
That is, the time offset estimation unit 210 of the present invention provides N_maf t_os (i) as input to the median averaging filter 220, and the median averaging filter 220 estimates the average value t_os (i) and calculates and outputs t_av (j) and the average value T3_av (j) of T3 (i) at that time. The average value t_av (j) of the reliable t_os (i) values output from the median average filter 220 and the average values T3_av (j) of the T3 (i) at that time are provided to the frequency offset estimation unit 230. The frequency offset estimation unit 230 can obtain each frequency offset f_err (j) by N_foe t_av (j) and T3_av (j) provided from the median averaging filter 220 and can be expressed as follows.
[ Equation 2]
T_av (j-1)] / [T3_av (j) - T3_av (j-1)
; (1 < j < N_foe)
F_err (1) = [t_av (N_foe) - t_av (1)] / [T3_av (N_foe) - T3_av
where f_err (j) = frequency offset [ppb]
t_av (j) = t_os (i) Mean value of values [sec]
T3_av (j) = average value of T3 (i) values [sec]
Accordingly, the frequency offset estimation unit 230 calculates N_foe frequency offsets f_err (1), f_err (2), ..., N_foe from N_foe t_av (j) and T3_av (j) provided from the median- and estimates f_err (N_foe). From this, the present invention determines the heterogeneity for each of the N_foe frequency offsets and takes a frequency offset value within the allowable condition. The method of
[ Equation 3]
INDEX (j) = 1; if number of [| f_err (j) -f_err (k) | ≪ TH_foe] > P / 2
(1? J? N_foe), (1? K? N_foe, k? J)
0 ; else
F_err = 1 / N_pass * [{? (F_err (j) * INDEX (j)} + f_err (1) * INDEX (1)
; (1 < j < N_foe)
where, F_err = final frequency offset (error)
N_pass = the number of INDEX (n) whose value is 1
t_av (j) = t_os (i) Mean value of values [sec]
T3_av (j) = average value of T3 (i) values [sec]
Therefore, the frequency offset estimation unit 230 of the present invention estimates frequency offsets f_err (1), f_err (2), ..., t_av (j) from T_av (N_foe) of the frequency offset threshold value TH_foe, and a difference value between the frequency offset and the remaining frequency offsets is obtained for the specific frequency offset. When the difference values are less than the frequency offset threshold value TH_foe [N_foe] / 2 or more, INDEX (N) = 0 when the number smaller than the frequency offset threshold value TH_foe is smaller than [N_foe] / 2, and is excluded from the final frequency offset F_err estimation.
The time offset between the client and the server can be more accurately performed by compensating the frequency error in the
FIG. 6 is a graphical representation of the application of the median averaging filter 220 of the present invention to observed network time protocol (NTP) time offsets.
In the figure, the x-axis represents the NTP response packet transmission time T3 (i) of the NTP server on a unix scale, and the y-axis represents the time offset.
(I), T2 (i), T3 (i), and T4 (i) in the
In the graph, the line shown without filter is averaged by applying N_maf = 80 to the time offset t_os (i) values indicated by the Origin Sample. The time offset average of N_maf = 80 shown in the filter without filter shows a smaller variation (y-axis) than the Origin samples. However, the excessively small or large t_os (i) values of N_maf t_os ) Values, which are non-negligible fluctuations in time offset values.
In the graph, a median filter averaged is used to obtain a standard deviation sigma of M (M < N_maf) time offset t_os (i) values using the median averaging filter 220 of the present invention by applying N_maf = 80, (j) of the time offsets and the average value T3_av (j) of the time offsets T3 (i) at that time are calculated and shown by judging that the values are reliable t_os (i) values when? is smaller than the threshold value TH_maf. The average value t_av (j) of the time offsets calculated by the median averaging filter 220 and the average value T3_av (j) of the T3 (i) at that time are calculated as T3 (i The average value t_av (j) of the time offsets is calculated.
FIG. 7 is a graph showing the processing result of the frequency offset estimation unit 230 provided with the output of the median averaging filter 220 of FIG. 6 with respect to the measured network time protocol (NTP) time offset. As described above, the median averaging filter 220 computes the average value t_av (j) of reliable t_os (i) values for N_maf = 80, i.e., the time offset t_os (i) And provides the calculated average value T3_av (j) to the frequency offset estimation unit 230. [ The graph in the figure shows the result of estimating the final frequency offset F_err by applying TH_foe = 500 [ppb] to N_foe = 30 for t_av (j) and T3_av (j). The final frequency offset F_err in FIG. 7 is obtained at 250 [msec] × N_maf × N_foe≈10 [min] when N_maf = 80 and N_foe = 30 at poll interval 250 [msec] The y-axis shows the final frequency offset F_err. The red line of the graph shows the result of performing the heterogeneity judgment by applying the INDEX (j) of Equation (3), and the blue line shows the final frequency offset F_err when the heterogeneity is not determined. In the case where the heterogeneity determination is not performed by applying INDEX (j) as shown in the graph, a case where the final frequency offset F_err is equal to or greater than ± 300 [ppb] due to a transient transmission / reception delay according to the network state has occurred. (j), it can be confirmed that the final frequency offset F_err is estimated to be within a range of ± 50 [ppb].
According to the frequency offset estimation system using the network time protocol (NTP) time offset of the present invention described above, time offset values outside the allowable range for the time offset values changing every packet in the NTP system are set to invalid values And estimating a more precise frequency error by calculating the final frequency error by judging the heterogeneity between the estimated frequency errors.
Although the system for estimating a frequency error using a network time protocol (NTP) time offset according to the present invention has been described with reference to a limited number of embodiments and drawings, the present invention is not limited thereto. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.
100: NTP server 200: NTP client
210: Time offset estimation unit 220: Median average filter
230: Frequency offset estimation unit
Claims (6)
Is provided in the NTP client (200) connected to the NTP server (100);
A time offset estimation unit (210) for obtaining a plurality of time offsets as time stamps of the transmission / reception NTP packets;
A median averaged filter (220) for extracting valid time offset information from a plurality of time offset information provided from the time offset estimation unit;
A frequency offset estimation unit (230) for estimating a frequency error using valid time offset information and time information provided from the median averaging filter;
And,
The time offset estimation unit 210,
The time T2 (i) of receiving the NTP packet from the NTP server 100, the NTP response packet transmission time T3 (i) of the NTP server 100 and the time T2 (i) At time T4 (i) received by the NTP client 200;
[Equation 1]
T_os (i) = 1/2 [{T2 (i) - T1 (i)} + {T3 (i) - T4 (i)}]; i = 1, 2, 3 ... , N_maf
T1 (i) = NTP packet transmission time of the client
T2 (i) = NTP packet reception time of the NTP server
T3 (i) = NTP response packet transmission time of the NTP server
T4 (i) = time at which the client receives the NTP response packet
(I) of the time offset t_os (i) between the NTP server 100 and the NTP client 200 provided to the NTP server 100 and provides the N_maf to the median averager 220. [
(M < N_maf) values for the N_maf t_os (i) values provided from the time offset estimation unit 210,
The standard deviation σ of M (M <N_maf) t_os (i) values is obtained,
(I) values of the t_os (i) values and the average value T3_av (j) of the T3 (i) values at that time are computed by judging that the standard deviation? Is smaller than the time offset threshold value TH_maf To the frequency offset estimation unit (230). The frequency offset estimation unit (230)
N_foe frequency offsets f_err (1), f_err (2), ..., N_foe from t_av (j) and T3_av (j) provided from the median averaging filter 220. and estimating f_err (N_foe) by using the following equation: f_err (N_foe)
T_av (j-1)] / [T3_av (j) - T3_av (j-1)
; (1 < j < N_foe)
F_err (1) = [t_av (N_foe) - t_av (1)] / [T3_av (N_foe) - T3_av
where f_err (j) = frequency offset [ppb]
t_av (j) = t_os (i) Mean value of values [sec]
T3_av (j) = average value of T3 (i) values [sec]
N_foe frequency offsets f_err (1), f_err (2) ... f_err (N_foe) is estimated,
If the difference is less than the frequency offset threshold value TH_foe [N_foe] / 2 or more, the N_foe frequency offsets are used to estimate the final frequency offset F_err , And excludes the difference values from the final frequency offset F_err estimation when the difference values are smaller than [N_foe] / 2, which is smaller than the frequency offset threshold value TH_foe.
N_foe frequency offsets f_err (1), f_err (2) ... f_err (N_foe) is estimated,
(N) = 1 when the number of the difference values is smaller than the frequency offset threshold value TH_foe is [N_foe] / 2 or more, thereby obtaining the difference frequency of the final frequency offset F_err And when the number smaller than the frequency offset threshold value TH_foe is smaller than [N_foe] / 2, INDEX (n) = 0 is excluded from the final frequency offset F_err estimation by the following equation (3) And estimates an offset F_err to compensate for the frequency error. The frequency error estimation system using the NTP time offset
& Quot; ( 3) & quot ;
INDEX (j) = 1; if number of [| f_err (j) -f_err (k) | ≪ TH_foe] > P / 2
(1? J? N_foe), (1? K? N_foe, k? J)
0 ; else
F_err = 1 / N_pass * [{? (F_err (j) * INDEX (j)} + f_err (1) * INDEX (1)
where, F_err = final frequency offset (error)
N_pass = the number of INDEX (n) whose value is 1
t_av (j) = t_os (i) Mean value of values [sec]
T3_av (j) = average value of T3 (i) values [sec]
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020150109999A KR101665924B1 (en) | 2015-08-04 | 2015-08-04 | Frequency offset estimation system using network time protocol time offset |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020150109999A KR101665924B1 (en) | 2015-08-04 | 2015-08-04 | Frequency offset estimation system using network time protocol time offset |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| KR101665924B1 true KR101665924B1 (en) | 2016-10-13 |
Family
ID=57174012
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| KR1020150109999A KR101665924B1 (en) | 2015-08-04 | 2015-08-04 | Frequency offset estimation system using network time protocol time offset |
Country Status (1)
| Country | Link |
|---|---|
| KR (1) | KR101665924B1 (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004199366A (en) * | 2002-12-18 | 2004-07-15 | Fujitsu Ltd | Method and system for setting time |
| KR100817798B1 (en) | 2006-10-20 | 2008-03-31 | 한국정보보호진흥원 | A method for estimating available bandwidth of network link using time stamp function of internet control message protocol |
| KR20090024170A (en) | 2006-05-19 | 2009-03-06 | 시메트리컴, 인코포레이티드 | Network time protocol precision timestamping service |
| JP2013118491A (en) * | 2011-12-02 | 2013-06-13 | Fujitsu Ltd | Frequency error correction device, frequency error correction method, frequency error correction program, and frequency error correction system for oscillator |
| US8976750B1 (en) | 2013-01-16 | 2015-03-10 | Sprint Communications Company L.P. | Delivering precision time protocol frequency and phase synchronization over a network without on-path support |
-
2015
- 2015-08-04 KR KR1020150109999A patent/KR101665924B1/en active IP Right Grant
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004199366A (en) * | 2002-12-18 | 2004-07-15 | Fujitsu Ltd | Method and system for setting time |
| KR20090024170A (en) | 2006-05-19 | 2009-03-06 | 시메트리컴, 인코포레이티드 | Network time protocol precision timestamping service |
| JP2009538101A (en) | 2006-05-19 | 2009-10-29 | シンメトリコム・インコーポレイテッド | Network time protocol precision time stamp service |
| KR100817798B1 (en) | 2006-10-20 | 2008-03-31 | 한국정보보호진흥원 | A method for estimating available bandwidth of network link using time stamp function of internet control message protocol |
| JP2013118491A (en) * | 2011-12-02 | 2013-06-13 | Fujitsu Ltd | Frequency error correction device, frequency error correction method, frequency error correction program, and frequency error correction system for oscillator |
| US8976750B1 (en) | 2013-01-16 | 2015-03-10 | Sprint Communications Company L.P. | Delivering precision time protocol frequency and phase synchronization over a network without on-path support |
| US8982776B1 (en) | 2013-01-16 | 2015-03-17 | Sprint Communications Company L.P. | Increasing accuracy for delivering precision time protocol frequency and phase synchronization over a network without on-path support |
Non-Patent Citations (2)
| Title |
|---|
| David Bladsjo et. al., "Synchronization Aspects in LTE Small Cells", IEEE Communications Magazine, September 2013 |
| Symmetricom, "Timing and Synchronization for LTE-TDD and LTE-Advanced Mobile Networks", white paper, 2013 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP2342850B1 (en) | A method for synchronizing clocks in a communication network | |
| US8730868B2 (en) | Network node, time synchronization method and network system | |
| CN100581164C (en) | Accurate time synchronization method and system facing measurement and control | |
| US8953645B2 (en) | Communication system, communication apparatus and time synchronization method | |
| US9698926B2 (en) | Distributed two-step clock | |
| CN101455014B (en) | Methods and devices for sending transmission-time or reception-time information for a transmitted or received message | |
| EP2228927A1 (en) | Method for processing distributed data having a chosen type for synchronizing communication nodes of a data packet network, and associated device | |
| US7630383B2 (en) | Synchronization of time stamps of peer devices in a communication node | |
| JP2008182385A (en) | Mobile communication system, time server and intra-station synchronization method used for the same | |
| KR20090071923A (en) | Method for synchronization using single timesync frame in bridged local area network and appratus thereof | |
| JP2013121014A (en) | Time synchronization device and method | |
| KR101775728B1 (en) | Apparatus and method for controlling network timing | |
| Murakami et al. | A packet filtering mechanism with a packet delay distribution estimation function for IEEE 1588 time synchronization in a congested network | |
| KR101665924B1 (en) | Frequency offset estimation system using network time protocol time offset | |
| US20220026857A1 (en) | Time transmission correction device, time transmission system, and delay measurement method | |
| CN110933096A (en) | Software-defined network time service system and time service method | |
| US9009282B2 (en) | Method for synchronizing a client clock frequency with a server clock frequency | |
| KR101605316B1 (en) | frequency error estimating apparatus using Rx delay in PTP | |
| US20230231641A1 (en) | Link profiling for asymmetric delay compensation | |
| EP3068076A1 (en) | Automatic determination of asymmetrical delay in transmission networks | |
| US20220217510A9 (en) | Dynamic weighing device | |
| US20160128012A1 (en) | Communication system, communication system control method, transmission device, and reception device | |
| US20160134387A1 (en) | Communication system, communication system control method, transmission device, and reception device | |
| US20230239817A1 (en) | Fronthaul network unit and method therein for synchronization over a fronthaul network | |
| EP3520253B1 (en) | Time synchronization in a live content distribution system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| AMND | Amendment | ||
| X701 | Decision to grant (after re-examination) | ||
| GRNT | Written decision to grant |