WO1998037651A1 - Synchronisation d'un reseau de telecommunication - Google Patents

Synchronisation d'un reseau de telecommunication Download PDF

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Publication number
WO1998037651A1
WO1998037651A1 PCT/FI1998/000099 FI9800099W WO9837651A1 WO 1998037651 A1 WO1998037651 A1 WO 1998037651A1 FI 9800099 W FI9800099 W FI 9800099W WO 9837651 A1 WO9837651 A1 WO 9837651A1
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WO
WIPO (PCT)
Prior art keywords
node
synchronization
quality level
priority
level
Prior art date
Application number
PCT/FI1998/000099
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English (en)
Inventor
Jukka Kainulainen
Original Assignee
Nokia Telecommunications Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nokia Telecommunications Oy filed Critical Nokia Telecommunications Oy
Priority to AU58676/98A priority Critical patent/AU5867698A/en
Publication of WO1998037651A1 publication Critical patent/WO1998037651A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0679—Clock or time synchronisation in a network by determining clock distribution path in a network
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
    • H04J3/0641—Change of the master or reference, e.g. take-over or failure of the master
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J2203/00—Aspects of optical multiplex systems other than those covered by H04J14/05 and H04J14/07
    • H04J2203/0001—Provisions for broadband connections in integrated services digital network using frames of the Optical Transport Network [OTN] or using synchronous transfer mode [STM], e.g. SONET, SDH
    • H04J2203/0089—Multiplexing, e.g. coding, scrambling, SONET
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
    • H04J3/0647—Synchronisation among TDM nodes

Definitions

  • the invention relates to synchronization of telecommunications networks in general, and in particular to synchronization methods in which the network nodes indicate the synchronization status of the transmitted signal.
  • the synchronization status indicates the signal quality level relative to synchronization, and thus the node can decide, on the basis of the quality levels received, which signal it is to use as its synchronization source.
  • node (or node equipment) is employed for the intersection point of links in a telecommunications network.
  • a node may be any device or equipment, for example a branching device or a cross- connection device.
  • synchronization may be performed either by means of separate synchronization connections or by utilizing the normal data connections between the system nodes. Separate synchronization connections are used only in isolated cases and very seldom to synchronize an entire network.
  • the line code must be such that the nodes are also capable of recognizing the clock frequency from the incoming data signal. Synchronization of the network nodes from these clock frequencies can be achieved by two basic methods: mutual synchronization and slave synchronization. In mutual syn- chronization, each node forms its own clock frequency from the mean value of the incoming signal frequencies and its current clock frequency. Hence, all nodes in the network drift towards a common mean frequency and in a steady state have reached said frequency.
  • slave synchronization all network nodes are synchronized with the clock frequency of one master node of the network. Each node selects one incoming signal frequency as the source for its clock frequency. The node seeks to select a signal having the clock frequency of the master node of the network.
  • independent slave synchronization each node makes its decisions about synchronization without receiving any external information to support the decision-making. When the nodes make their decisions on synchronization independently, each node must determine with which node it is syn- chronized.
  • the node selects from valid incoming signals the one having the highest priority, i.e. the one highest on the list, as its synchronization source. If this signal is lost or its quality deteriorates so that it is no longer acceptable as a synchronization source, the node selects from the list the signal having the next-highest priority.
  • the priority list must be compiled in such a way that all nodes on the list are located between the node in question and the master node of the network, and thus synchronization is distributed from the master node to the lower levels.
  • independent slave synchronization poses limitations to network synchronization: in looped networks, all links cannot be used for synchronization, and hence the dynamic adaptability of the network in different situations is limited. Communication must be present between the nodes in order for the information possessed by an individual node to be sufficient for decision-making in all situations without any need to strongly limit the number of links utilized for synchronization, in which case the clock frequency of the master node could not be distributed as easily to the network nodes. There are two methods for such communication, which will be described in the following.
  • LP synchroniza- tion seeks to prevent the timing from drifting into an inoperative state in looped networks by using two state bits, mcb and lcb, as an aid to the above priority lists, the bits being transmitted between network nodes.
  • the first state bit, the master control bit (mcb) indicates whether synchronization is derived from the master network node.
  • the master node defined for the network sends this bit as a logical zero in its outgoing signals, and the other nodes relay it further, if they are synchronized with a signal in which the mcb bit has the value zero.
  • the other state bit indicates whether there is a loop in the synchronization.
  • Each node in the network sends this bit as a logical one in the direction in which it is synchronized and as a logical zero in other direc- tions.
  • Figure 1 illustrates, as an example, a telecommunications network comprising five nodes A...E and using the LP synchronization described above.
  • the mcb and lcb bits sent by each node in different directions are marked next to nodes by using reference marks M (mcb bit) and L (lcb bit).
  • the priority lists used by the nodes are marked by using reference mark PL.
  • Reference marks P A , P B and P c mark the ports of each node.
  • the priority list PL of the master node has no incoming signals as the master node always uses its internal oscillator as the synchronization source. Links not used by synchronization at the moment are shown with dotted lines.
  • Node D is synchronized with node B, because port P A is higher on its priority list than port P c .
  • a synchronization tree is formed from tree-like hierarchical structures, whereas in LP synchronization the synchronization tree is formed by using loops.
  • a master loop including the master node of the network is formed and after this, nodes are added to the synchronization- tree one chain at a time until all nodes are included.
  • Priority lists are formed in accordance with the loops and the chains.
  • the master loop consists of nodes A, B, D and C, in this order.
  • a chain of one node (node E) has been connected to this master loop.
  • Figures 2a and 2b illustrate the behavior of a network using LP synchronization (Figure 1) when an error occurs.
  • Figure 1 the connection between master node A and node B is lost.
  • the network receives synchronization from master node A via node C.
  • Figure 2b the connection between nodes A and C is also lost and node C becomes the new master node as it was the last one to relay master node frequency to the network.
  • the mcb bit transmitted by node C is now a logical one stating that there is no connection to the official master node of the network.
  • SSM synchronization status messages
  • G.704 defines the frame structure of a digital transmission system operating at a rate of 2048 kbit/s.
  • bits 4-8 in every second frame are spare bits and may be used e.g. to transport the above synchronization status messages. Only one of bits 4-8 in a frame can be used for this purpose, and thus a four-bit synchronization status message is made up of a selected bit (4-8) in frames 1, 3, 5, and 7 and in frames 9, 11 , 13, and 15 of the multiframe.
  • SSM synchronization status messages
  • G.708 The same synchronization status messages (SSM) are defined in recommendation G.708 for SDH networks.
  • the synchronization status messages are transported in bits b5...b8 of byte S1 in the section overhead (SOH) of the STM-N frame.
  • QL synchronization quality levels
  • FIGS 3 and 4 illustrate the operation of the SSM method in a ring- shaped network having five nodes in all, denoted by references N1...N5.
  • the quality level of the node's internal clock QL1011
  • the priority list of the node Beneath that the priority list of the node is shown, wherein the selected timing source is indicated in italics.
  • each node selects as its timing source the signal having the highest quality level as indicated by the synchronization message included therein. If several signals have the same quality level, the one highest on the priority list is selected.
  • the synchronization status message transmitted by each node is shown with the reference "Q .xxxx" beside each port of the node.
  • External timing sources S1 and S2 are connected to the master node N1 and to node N3, respectively.
  • a QL value must be given to each source external of the loop synchronization.
  • FIG 3 shows the network in a normal situation (no failures).
  • the master node transmits this synchronization status message in both directions.
  • Figure 4 shows a situation in which a failure condition has occurred on the connection between nodes N1 and N2.
  • a disadvantage of the synchronization methods using synchroniza- tion status messages is that the network using the methods cannot flexibly utilize the backup clock in the network when an error occurs, for example, when the connection to the master clock is lost. Thus, the ability of the network to recover from failure situations is inadequate. These failure situations are described in more detail later in this document.
  • the objective of this invention is to eliminate the above-mentioned problem and to improve synchronization methods of the type described above so that a backup clock can be used effectively in the network. This objective can be achieved by using the solution defined in the independent patent claims.
  • the idea of this invention is to interconnect the location of the source in the priority list and the synchronization status (quality level as regards the synchronization) of the source. Hence the idea is to add to the prior- ity list information about the synchronization status that a certain synchronization source must have in order that it could be on a certain level in the priority list. The idea can also be implemented by keeping a separate priority list for each synchronization status.
  • networks of the type described above can flexibly use the backup clock and synchronize themselves again with the master clock when the master clock becomes available.
  • the solution in accordance with the invention can be used to improve the fault and interference tolerance of the network and thus to improve its reliability.
  • the solution also offers more flexibility to the parameterizing of synchroni- zation on the network level as the priority list does not need to be defined only on the basis of the location of the network master clock, but possible backup clocks can also-be taken into account.
  • Figure 1 illustrates a telecommunications network using LP synchronization
  • Figures 2a and 2b illustrate the behavior of the network in Figure 1 in failure situations
  • Figure 3 illustrates a telecommunications network using SSM synchronization
  • Figure 4 illustrates the behavior of the network in Figure 3 in failure situa- tions
  • Figures 5a...5f illustrate a problem related to the LP synchronization when the backup clock of the network is on the same level as the master clock
  • Figures 6a...61 illustrate a problem related to the LP synchronization when the backup clock of the network is on a different level than the master clock
  • Figures 7a and 7b illustrate the basic idea in accordance with the invention
  • Figures 8a...80 illustrate the operation of the method in accordance with the invention
  • Figure 9 is a flow chart illustrating the process of synchronization source selection carried out by an individual node
  • Figure 10a is a block diagram illustrating those parts of the node which implement the method in accordance with the invention
  • Figures 10b and 10c illustrate alternative ways of implementing a node.
  • node C starts using backup clock BM (which is of the same quality as the master clock) which has priority 3.
  • BM which is of the same quality as the master clock
  • node C has noticed the changed bits of node D and synchronizes itself now via node D with the master clock. Additionally, node C has updated its outgoing bits.
  • node B notices that there is now con- nection to the master clock via node C and thus node B synchronizes itself with node C and updates its own outgoing bits.
  • the situation is now stable and the nodes are synchronized with the master clock in accordance with the chain M ⁇ A ⁇ D ⁇ C ⁇ B.
  • FIGS 7a and 7b illustrate this principle by using the example network described above.
  • the priorities shown in Figure 7a are used when selecting the timing source from the signals having said status.
  • the priorities shown in Figure 7b are used when selecting the timing source from the signals having said status.
  • the idea is to define different priorities to different statuses, that is, make the location of the source on the priority list dependent on the synchronization status of the source.
  • FIGs 8a...8o illustrate the operation of the network described above when the priorities shown in Figures 7a and 7b are used in the network.
  • the backup clock is still assumed to be on the slave level.
  • FIG 8a illustrates the same start situation as in the previous example.
  • node B updates the identifier it transmits to node C.
  • the backup clock BM is connected to node C on the slave level, the node has two sources of slave level. From these, the backup clock BM is selected as it has the first priority on the slave level (see Figure 7b).
  • the slave-level con- nection to node B is not included in the sources to be used.
  • node C synchronizes itself with the backup clock BM and transmits the information
  • nodes B and D have noticed the changed status of node C.
  • Node B synchronizes itself with node C, because node C has the first priority on the slave level and thus it is better than the internal clock on the slave level.
  • node D notices that the status of node
  • node C receives the changed status of node D and changes from the backup clock to node D, because it can get the master clock frequency from node D. Node C updates its outgoing statuses.
  • Node B remains synchronized with node C, but updates the status it transmits to node C. The situation is stable at this stage.
  • node C has noticed the change that has taken place. Now node C has two sources (BM and D) available on the slave level and only the backup clock has been assigned priority on the slave level. Thus, node C synchronizes itself with backup clock BM.
  • nodes B and D have processed the slave status coming from node C. This status is the best these nodes can get and it has a higher priority than the internal clock which is also on the slave level. Thus, nodes B and D synchronize via node C with the backup clock BM.
  • the network is successfully synchronized with the backup clock when the connection to the master clock has been lost.
  • FIG. 8j the connection between nodes A and D is restored.
  • Node D synchronizes via node A with the master clock after receiving the master clock status from node A.
  • node C receives the master clock status from node D and changes node D to its synchronization source.
  • node B also receives the master clock status (from node C) so it remains synchronized with node C and updates its outgoing status. The situation is stable now. The connection to the master clock has been restored and the nodes have successfully changed the master clock to their synchronization source.
  • node priority lists have only included different sources (interfaces or ports) in the order of priority, for example, in accordance with the following table:
  • the signal with the best status has been selected as the synchronization source for the node. If the same status has several signals, the signal whose interface is highest on the priority list has been selected as the synchronization source.
  • the node priority list is formed in such a manner that it includes both the different sources and the synchronization statuses required for a source to have the priority in question. For example, the previous example could in this case look as follows, when using LP synchronization as an example.
  • the same interface can be on the priority list several times as several different statuses can be received through it.
  • the node actually has a priority list for each desired status.
  • a synchronization source When a synchronization source is selected in a node operating in accordance with the invention, the procedure is otherwise the same as in the known methods (i.e. finding the highest possible status and selecting from the sources having this status the one that has the highest priority), but now the node does not have just one common priority list, but each status level can have its own definitions.
  • the node selects from the sources having the same status the one which has the highest priority, it must use the priority definitions related to this status.
  • Figure 9 is a flow chart illustrating the decision process carried out by the node.
  • the node searches for the highest available status (stages 91...93).
  • the node searches among the sources transmitting said status for the one which is highest on the priority list (or part of it) related to said status (stage 94).
  • stage 94 the priority list
  • the "Do not use” status is ignored.
  • the process does not even proceed to the "Do not use” status. If a source is faulty, it is assigned the "Do not use” status.
  • the highest available status is retrieved first and then, from the sources transmitting this status, the one which has the highest priority on this status.
  • the primary criterion for selection is the status (the quality level).
  • Figures 10a...10c illustrate as a functional block diagram the parts which implement the above-described method on an individual node of the network.
  • the general structure of the node is, for example, such that it comprises several parallel interface units IU1, IU2...IUN, each of which is connected to at least one neighboring node, and a control unit which is common to all interface units and which makes the decisions concerning synchronization.
  • the control unit and the different interface units are interconnected, for exam- pie, via the internal bus CBUS of the node.
  • the figures show two links, A., and A 2 , coming from the neighboring nodes to the system node as an example. Both links are connected to their own interface units.
  • the links are, for example, 2 Mbit/s PCM links in accordance with ITU-T recommendations G.703 and G.704.
  • One interface unit IU can have one or several interfaces through which the node is connected to one or several neighboring nodes. Generally, it can be stated that the node has N interface units which have M interfaces (M>N).
  • Block 13 relays the synchronization status messages or bits forward to the synchronization block 16
  • the synchronization blocks 16, perform, for example, the checking of the correctness of the messages, and relay the synchronization status forward to the centralized synchronization control block 20 of the node via bus CBUS.
  • the signal transmit/receive blocks also monitor the quality of the received signal and save this information to interface-specific fault data- bases 14,.
  • Each synchronization block receives the fault information from the corresponding database.
  • the synchronization block transmits the status "Do not use for synchronization" to the control block.
  • the synchronization control block 20 saves the synchronization statuses of the different sources, received from the synchronization blocks, to memory area 21.
  • the control block 20 retrieves from the memory area 21 the highest possible status received at the moment and the sources transmitting it. After this, the control block uses the priority list stored in the memory area 22 to select from the sources trans- mitting said status the one which has the highest priority relating to that status.
  • Outgoing status messages are formed in the synchronization blocks 1 ⁇ i ⁇ and when a change in the synchronization source causes changes in the outgoing status information, the control block informs the synchronization blocks of the change.
  • the method can be implemented also by using, for example, the type of node architecture illustrated in Figure 10b. In this case the structure of the node is otherwise the same, but the priority lists have been distributed to different interface units and each interface unit informs the other interface units of its signal status. After receiving this information from others, each interface unit can make a conclusion corresponding to the one made in the centralized control block in the previous example and form the outgoing status information independently.
  • the idea in accordance with the invention can be implemented either by interconnecting the status and the priority list level or by using status- specific priority lists, in which case each status of a different level has its own list. There can be a list for every possible status or just for selected statuses.
  • the control block 20 has a separate priority list for each status and the control block uses the list which is related to the highest status received at the mo- ment. This kind of solution is illustrated in Figure 10c.
  • the method can be implemented (as described above) in such a way that a source gets a certain priority level when it has exactly the same status as the one defined for the priority level in question.
  • this defined status can be used as a minimum requirement.
  • the source is always on the priority level corresponding to said minimum value when the quality level of the signal received from the interface is of the minimum value or higher, and no other minimum value of the quality level has been defined for the interface, this other minimum value being higher than said minimum value, but lower or equal to the current quality level (status) of the signal.
  • the system uses the priority which the source gets when it has a status which is the highest of the statuses for which a priority level has been defined and which are lower than the current status of the source.
  • the invention was implemented by always defining the status level required for a certain priority level. This definition can also be skipped on some priority levels in which case the source in question has the priority defined for the status that is one level lower. If this status has no priority either, the status that is one level lower is used, etc., until the priority defined for the source can be found. If no priority is found even when the lowest al- lowed status is reached, the source is not supposed to be used for synchronization with these priorities. If the implementation is done by using only one priority list into which the required status has been added and not by using priority lists belonging to different statuses, the required status level of a source need not be defined and the source can be put into the priority list without the status requirement. In this case the source always gets this priority in comparisons regardless of its status level.
  • quality levels are not necessarily received from all of the sources, but the quality level can be defined in the interface in the node so that when the signal is in order, the node assigns this quality level to the signal coming to this interface.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)
  • Time-Division Multiplex Systems (AREA)

Abstract

L'invention concerne un procédé permettant de synchroniser un réseau de télécommunication comprenant plusieurs noeuds (A... D) reliés par des voies de transmission. Les noeuds du réseau transmettent des messages de synchronisation qui sont utilisés pour préciser le niveau de qualité du signal correspondant en ce qui concerne la synchronisation. Une liste de priorité, contenant les interfaces des noeuds sur différents niveaux de priorité, est formée dans chaque noeud. Celui-ci utilise comme source de synchronisation, parmi les différentes sources possibles, le signal ayant le niveau de qualité le plus élevé. Afin que la synchronisation utilise plus efficacement les horloges de secours, le noeud stocke les informations pour chaque niveau de priorité de chaque interface, les informations précisant le niveau de qualité que doit avoir le signal provenant de l'interface en question afin que celle-ci soit sur le niveau de priorité en question; il recherche le niveau de qualité le plus élevé qu'ont les signaux reçus; puis, parmi les signaux émis par les interfaces ayant ledit niveau de qualité, il sélectionne celui qui a la priorité la plus élevée sur le niveau de qualité en question et l'utilise comme source de synchronisation.
PCT/FI1998/000099 1997-02-19 1998-02-03 Synchronisation d'un reseau de telecommunication WO1998037651A1 (fr)

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Application Number Priority Date Filing Date Title
AU58676/98A AU5867698A (en) 1997-02-19 1998-02-03 Synchronization of telecommunications network

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI970700 1997-02-19
FI970700A FI102442B (fi) 1997-02-19 1997-02-19 Tietoliikenneverkon synkronointi

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Cited By (7)

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WO2000019649A1 (fr) * 1998-09-25 2000-04-06 Nokia Networks Oy Noeud d'acces dans un systeme de telecommunications
WO2002039630A2 (fr) * 2000-11-07 2002-05-16 Telefonaktiebolaget Lm Ericsson (Publ) Gestion d'un reseau de synchronisation
EP1583266A2 (fr) * 2004-03-31 2005-10-05 Tellabs Denmark A/S Synchronisation de services MRT sur réseaux de paquets
EP1601124A1 (fr) * 2004-05-28 2005-11-30 Hitachi, Ltd. Procédé et dispositif pour synchroniser des horloges de noeuds de réseau
WO2011060965A1 (fr) * 2009-11-19 2011-05-26 Telefonaktiebolaget L M Ericsson (Publ) Configuration de réseau de synchronisation
EP2897312A4 (fr) * 2012-09-28 2015-10-14 Huawei Tech Co Ltd Procédé, système et dispositif de synchronisation d'horloge
EP3282605A4 (fr) * 2015-04-08 2018-04-25 ZTE Corporation Procédé et appareil de configuration pour réseau de synchronisation

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US4837850A (en) * 1986-09-03 1989-06-06 U.S. Philips Corp. Hierarchic synchronization method and circuit arrangement for exchanges of a mesh telecommunication network
US4939752A (en) * 1989-05-31 1990-07-03 At&T Company Distributed timing recovery for a distributed communication system
US5386418A (en) * 1991-08-19 1995-01-31 Fujitsu Limited Method for synchronizing synchronous data communication network and communication device used in the synchronous data communication network
US5475717A (en) * 1990-12-11 1995-12-12 Alcatel Business Systems Method of ensuring that each node of a private telecommunication network is synchronized to the best available clock at all times

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US4736393A (en) * 1986-04-16 1988-04-05 American Telephone And Telegraph Co., At&T Information Systems, Inc. Distributed timing control for a distributed digital communication system
US4837850A (en) * 1986-09-03 1989-06-06 U.S. Philips Corp. Hierarchic synchronization method and circuit arrangement for exchanges of a mesh telecommunication network
US4939752A (en) * 1989-05-31 1990-07-03 At&T Company Distributed timing recovery for a distributed communication system
US5475717A (en) * 1990-12-11 1995-12-12 Alcatel Business Systems Method of ensuring that each node of a private telecommunication network is synchronized to the best available clock at all times
US5386418A (en) * 1991-08-19 1995-01-31 Fujitsu Limited Method for synchronizing synchronous data communication network and communication device used in the synchronous data communication network

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000019649A1 (fr) * 1998-09-25 2000-04-06 Nokia Networks Oy Noeud d'acces dans un systeme de telecommunications
WO2002039630A2 (fr) * 2000-11-07 2002-05-16 Telefonaktiebolaget Lm Ericsson (Publ) Gestion d'un reseau de synchronisation
WO2002039630A3 (fr) * 2000-11-07 2002-08-01 Ericsson Telefon Ab L M Gestion d'un reseau de synchronisation
US6711411B1 (en) 2000-11-07 2004-03-23 Telefonaktiebolaget Lm Ericsson (Publ) Management of synchronization network
EP1583266A3 (fr) * 2004-03-31 2007-07-11 Tellabs Denmark A/S Synchronisation de services MRT sur réseaux de paquets
EP1583266A2 (fr) * 2004-03-31 2005-10-05 Tellabs Denmark A/S Synchronisation de services MRT sur réseaux de paquets
EP1601124A1 (fr) * 2004-05-28 2005-11-30 Hitachi, Ltd. Procédé et dispositif pour synchroniser des horloges de noeuds de réseau
WO2011060965A1 (fr) * 2009-11-19 2011-05-26 Telefonaktiebolaget L M Ericsson (Publ) Configuration de réseau de synchronisation
RU2504086C1 (ru) * 2009-11-19 2014-01-10 Телефонактиеболагет Л М Эрикссон (Пабл) Конфигурация сети синхронизации
US9647784B2 (en) 2009-11-19 2017-05-09 Telefonaktiebolaget Lm Ericsson (Publ) Configuration of synchronisation network
US10211941B2 (en) 2009-11-19 2019-02-19 Telefonaktiebolaget Lm Ericsson (Publ) Configuration of synchronisation network
US10790921B2 (en) 2009-11-19 2020-09-29 Telefonaktiebolaget Lm Ericsson (Publ) Configuration of synchronisation network
EP2897312A4 (fr) * 2012-09-28 2015-10-14 Huawei Tech Co Ltd Procédé, système et dispositif de synchronisation d'horloge
US9641268B2 (en) 2012-09-28 2017-05-02 Huawei Technologies Co., Ltd. Method, system and device for synchronizing clocks
EP3282605A4 (fr) * 2015-04-08 2018-04-25 ZTE Corporation Procédé et appareil de configuration pour réseau de synchronisation

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FI970700A (fi) 1998-08-20
FI102442B1 (fi) 1998-11-30
FI102442B (fi) 1998-11-30
FI970700A0 (fi) 1997-02-19
AU5867698A (en) 1998-09-09

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