WO2023243030A1 - Dispositif de transmission tdm optique, procédé de synchronisation, et programme de synchronisation - Google Patents

Dispositif de transmission tdm optique, procédé de synchronisation, et programme de synchronisation Download PDF

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Publication number
WO2023243030A1
WO2023243030A1 PCT/JP2022/024086 JP2022024086W WO2023243030A1 WO 2023243030 A1 WO2023243030 A1 WO 2023243030A1 JP 2022024086 W JP2022024086 W JP 2022024086W WO 2023243030 A1 WO2023243030 A1 WO 2023243030A1
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Prior art keywords
signal
timing
reception
optical
tdm transmission
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PCT/JP2022/024086
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English (en)
Japanese (ja)
Inventor
公太 西山
雅弘 中川
佳奈 益本
俊哉 松田
剛志 関
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日本電信電話株式会社
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Priority to PCT/JP2022/024086 priority Critical patent/WO2023243030A1/fr
Publication of WO2023243030A1 publication Critical patent/WO2023243030A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/42—Loop networks
    • H04L12/427—Loop networks with decentralised control
    • H04L12/43—Loop networks with decentralised control with synchronous transmission, e.g. time division multiplex [TDM], slotted rings
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/44—Star or tree networks

Definitions

  • the present invention relates to an optical TDM transmission device, a synchronization method, and a synchronization program.
  • TDM time division multiplexing
  • FIG. 15 is an explanatory diagram showing signals used in optical TDM transmission and signals used in a normal transmission network.
  • the signal 801 is a "continuous signal” in which a single signal occupies the same line and the same wavelength transmission path. Continuous signals are optical signals used in existing link systems.
  • the signal 802 is a "burst signal” in which a plurality of signals are divided by a fixed time width (time slot: TS) on the time axis on the same line and the same wavelength transmission path.
  • TS time slot
  • a burst signal is an optical signal that is intermittent on the time axis, and in TDM transmission, data is superimposed on this burst signal and transmitted. Between burst signals, there is a no-signal period (guard time: GT) in which the optical power is approximately 0.
  • multiple nodes (transmission equipment) connected on the same line transmit burst signals on the same wavelength at different times to avoid collisions between signals.
  • a state in which burst signals can reach the destination receiving end without colliding with each other is called a synchronous state.
  • PON Passive Optical Network
  • OLT Optical Line Terminal
  • ONU Optical Network Unit
  • P2MP Point to Multi-point
  • the OLT measures the RTT (Round Trip Time) between each ONU in advance, calculates the timing at which the signals from each ONU will not collide, and notifies each ONU of the timing to synchronize the ONUs. Above, the OLT instructs each ONU regarding the timing of signal transmission.
  • RTT Red Trip Time
  • FIG. 11 is a configuration diagram of the TDM-PON system described in Non-Patent Document 1.
  • an OLT is connected to each ONU through an optical fiber.
  • Optical fibers from the OLT are branched to each ONU via an optical splitter SP.
  • the signal flow from the OLT to the ONU will be referred to as a "downstream signal”
  • the signal flow from the ONU to the OLT will be referred to as an "upstream signal.”
  • FIG. 12 is a sequence diagram showing the signal flow in the TDM-PON system of FIG. 11.
  • the OLT transmits a downlink continuous signal for RTT measurement to the ONU at time t0.
  • the destination ONU sets the time to t0 at the timing of receiving the downlink continuous signal from the OLT (S11).
  • the ONU transmits an uplink burst signal for RTT measurement at time t1 specified by the OLT.
  • the OLT obtains time t2 at which the uplink burst signal is received (S12). Thereby, the OLT calculates the RTT with the ONU based on the timestamps from time t0 to t2.
  • the OLT transmits the transmission timing of a data signal using burst light to the ONU (S13).
  • the ONU transmits a data signal using burst light based on the notified timing (S14).
  • FIG. 13 is a configuration diagram of a TDM-PON system in a 1-to-N optical connection (P2MP optical connection) network described in Non-Patent Documents 1 and 2.
  • a continuous down signal P11 from the OLT to each ONU and a signal P13 in which the up burst signal P12 from each ONU to the OLT is multiplexed propagate between nodes.
  • the downlink signal P11 is, for example, a Sync signal (S11) and a timing notification signal (S13) used in the RTT measurement in FIG. 12.
  • the upstream signal P12 is, for example, the Sync signal (S12) in FIG. 12 and the data signal (S14) addressed to another ONU.
  • the OLT achieves synchronization accuracy of several tens to hundreds of nanoseconds by measuring RTT every time each ONU transmits and receives a data signal (S14).
  • FIG. 14 is a configuration diagram of a TDM-PON system in an N-to-M optical connection network.
  • the set be the receiving side of the Metro network.
  • the transmitting side ONU corresponds to the ONU that is the transmitting source of the data signal P12.
  • the receiving side ONU refers to an ONU that receives the data signal P13.
  • a data signal P14 that is transmitted (replyed) from the receiving ONU to the transmitting ONU.
  • the data signal P14 heading from the receiving side ONU to the sending side ONU is in the same direction as the downlink signal P11 in FIG. 13 heading towards the sending side ONU.
  • a Sync signal is added to the data signal through electrical processing in the OLT, and the downlink signal is transmitted to each ONU as a continuous signal, but in an N-to-M optical connection network that does not include electrical termination between nodes, In an OLT equivalent, it is not possible to add a Sync signal to the data signal P14 and transmit it as a continuous signal. Therefore, the conventional synchronization method used in the existing TDM-PON system cannot be directly applied to an N-to-M optical connection network.
  • FIG. 16 is an explanatory diagram of the transmission cycle of TDM transmission.
  • Time slots are divided into periods T and assigned to each ONU. This period is called the TDM frame length.
  • a first ONU may transmit one data signal in a first period T and another data signal in a next period T.
  • the GT provided between time slots plays the role of absorbing signal deviations (synchronization errors).
  • FIG. 17 is an explanatory diagram of signal collision of burst signals flowing from left to right.
  • a first data signal 811A, a second data signal 811B, and a third data signal 811C are sequentially superimposed on the optical fiber.
  • the time slot of the first data signal 811A and the time slot of the second data signal 811B partially overlap, resulting in signal collision.
  • a first data signal 812A, a second data signal 812B, and a third data signal 812C are sequentially superimposed onto the optical fiber.
  • the time slots of each data signal can be correctly superimposed without overlapping.
  • the main objective of the present invention is to avoid collisions between data signals during multiplexing without measuring the RTT for each node in an optical TDM transmission network with N-to-M optical connections.
  • the optical TDM transmission device of the present invention has the following features.
  • the present invention provides an optical TDM transmission system in which a plurality of optical TDM transmission devices transmit data signals while synchronizing time slots between nodes.
  • Each of the optical TDM transmission devices In a first period before superimposing the data signal, a timing signal periodically transmitted to each of the optical TDM transmission devices is received a plurality of times, and the reception time and reception period of the received timing signal are determined as described above.
  • the reception timing of the timing signal In the second period in which the data signal is superimposed, the data signal transmitted from itself is controlled to be superimposed on a time slot determined based on the stored reception timing.
  • FIG. 1 is a configuration diagram of a TDM transmission system in an N-to-M optical connection network according to the present embodiment.
  • FIG. 2 is a configuration diagram when the N-to-M optical connection network of FIG. 1 according to the present embodiment is applied to a network having a ring topology.
  • FIG. 3 is an explanatory diagram of the T transmitter in the second period according to the present embodiment.
  • FIG. 4 is an explanatory diagram of time slots forming the burst signal of FIG. 3 according to the present embodiment.
  • FIG. 3 is a time-series time slot diagram showing a timing signal extraction method according to the present embodiment.
  • FIG. 6 is a time slot diagram in which a part of FIG. 5 is enlarged according to the present embodiment. It is a block diagram of the T transmitter regarding this embodiment.
  • FIG. 2 is a configuration diagram of a node related to this embodiment.
  • FIG. 3 is a sequence diagram showing details of node operation according to the present embodiment.
  • FIG. 1 is a hardware configuration diagram of an optical TDM transmission device according to the present embodiment. 1 is a configuration diagram of a TDM-PON system described in Non-Patent Document 1.
  • FIG. 12 is a sequence diagram showing a signal flow in the TDM-PON system of FIG. 11.
  • FIG. 1 is a configuration diagram of a TDM-PON system in a 1-to-N optical connection (P2MP optical connection) network described in Non-Patent Documents 1 and 2.
  • FIG. FIG. 1 is a configuration diagram of a TDM-PON system in an N-to-M optical connection network.
  • FIG. 2 is an explanatory diagram showing signals used in optical TDM transmission and signals used in a normal transmission network.
  • FIG. 2 is an explanatory diagram of a transmission cycle of TDM transmission.
  • FIG. 3 is an explanatory diagram of signal collision of burst signals flowing from left to right.
  • FIG. 1 is a configuration diagram of a TDM transmission system in an N-to-M optical connection network.
  • the optical TDM transmission system in FIG. 1 includes a T (Timing) transmitter 30 instead of the OLT that measures RTT with each ONU on the transmitting side (2-way synchronization processing) in FIG. 14.
  • the T transmitter 30 transmits a timing signal P15 to each node on the transmitting side using one time slot on the same wavelength as the data signal.
  • Each node on the transmitting side receives the timing signal P15, and stores the period and reception time of the received timing signal P15 in itself as a reception timing.
  • the timing signal P15 is transmitted in the following two stages.
  • the first period is a preparation period for each node to grasp the transmission timing of data signals for each wavelength. During this period, transmission of data signals is prohibited.
  • the T transmitter 30 transmits only the periodic timing signal P15, and each node stores the received timing signal P15 as a reception timing.
  • a time slot synchronization state between the nodes is achieved in which the propagation delay time for each wavelength is indirectly corrected.
  • each node receives the timing signal that is periodically transmitted to each node multiple times in the first period before superimposing the data signal, and determines the reception time and reception cycle of the received timing signal by timing It is stored as the signal reception timing.
  • the second period is an operating period in which signal transmission is permitted according to the time slot on which the data signal that each node grasped in the first period is superimposed.
  • each node superimposes the data signal P12 on a time slot determined based on the reception timing of the timing signal P15.
  • a signal P13 in which the timing signal P15 and the data signal P12 are multiplexed at the same wavelength flows on the optical path.
  • Each node on the receiving side receives the desired data signal P13 from the signal P13.
  • the T transmitter 30 may continue to transmit the periodic timing signal P15 in the second period as well as in the first period.
  • each node adjusts (fine time correction) the previously stored reception timing from the timing signal P15 received in the second period and updates it as the current reception timing.
  • each node can continuously and accurately grasp the time slots in which data signals are superimposed, not only in the first period but also in the second period, by autonomously extracting timing signals in the physical layer. be. This means that even in an environment where the physical properties of the optical fiber change due to changes in temperature, etc., it is possible to continuously maintain the time slot synchronization state with high accuracy.
  • FIG. 2 is a configuration diagram when the N-to-M optical connection network of FIG. 1 is applied to a network having a ring topology.
  • three nodes are placed on the left side of the drawing as the transmitting side, and three nodes are placed on the right side of the drawing as the receiving side.
  • four nodes are placed on the left side of the drawing as transmitters, and five nodes are placed on the right side of the drawing as receivers.
  • the T transmitter 30 transmits a timing signal T to the four nodes on the transmitting side. That is, the starting point of the timing signal T is the T transmitter 30 in both FIG. 1 and FIG.
  • the four nodes on the transmitting side superimpose the data signal D on the timing signal T.
  • the five nodes on the receiving side receive the timing signal T and the data signal D.
  • FIG. 3 is an explanatory diagram of the T transmitter 30 in the second period.
  • T transmitter 30 transmits timing signal P15 to node A.
  • Node A receives the timing signal P15 and transmits the data signal transmitted from node A using the same wavelength as the timing signal P15.
  • the node B extracts only the timing signal P15 from the timing signal P15 and the data signal transmitted from the node A, and transmits the data signal transmitted from the node B using the same wavelength as the timing signal P15.
  • Node C extracts only timing signal P15 from the timing signal P15 and the data signals transmitted from nodes A and B, and transmits the data signal transmitted from node C using the same wavelength as timing signal P15. do.
  • the timing signal P15 and the data signal P12 transmitted from each node A, B, and C are multiplexed as a signal P13.
  • FIG. 4 is an explanatory diagram of time slots forming the burst signal P13 of FIG. 3.
  • Reference numeral 101 is a time slot of wavelength ⁇ 1 at the time when the T transmitter 30 first transmits the timing signal T. Each node receives a timing signal T. A timing signal T is periodically inserted according to a signal-specific pattern indicated by reference numeral 103, and the other time slots are empty slots.
  • Reference numeral 102 is a time slot of wavelength ⁇ 1 at the time when a certain node transmits (superimposes) a data signal as a burst signal (burst light) to the empty slot 101.
  • FIG. 5 is a chronological time slot diagram showing a timing signal extraction method.
  • FIG. 6 is a time slot diagram in which a part of FIG. 5 is enlarged.
  • the coloring pattern of each signal is the same as the reference numeral 103 in FIG.
  • Each node considers a signal received at a signal extraction timing equal to or less than timing T0 ⁇ GT for each predetermined period as a new timing signal T.
  • Each node corrects the predetermined period and timing T0 based on the new timing signal T, and sets the next signal extraction timing.
  • each node sets and corrects the reception timing, which is the reference for superimposing the data signal D, when receiving the timing signal. In this way, by once storing the reception timing, it is possible to continue to understand and extract the reception timing of the timing signal T while correcting the reception timing thereafter.
  • FIG. 7 is a configuration diagram of the T transmitter 30.
  • the T transmitter 30 includes a clock section 31, a counter management section 32, a control section 33, and a timing signal transmission section 34.
  • the clock section 31 supplies a clock to the counter management section 32.
  • the counter management unit 32 counts the time from transmitting a timing signal until transmitting the next timing signal as a counter value based on the clock from the clock unit 31.
  • the control unit 33 controls the timing signal transmission unit 34 to continue periodically transmitting the timing signal based on the counter value notified from the counter management unit 32.
  • the timing signal transmitter 34 transmits a timing signal under the control of the controller 33. This allows each node on the transmitting side to continue receiving timing signals periodically.
  • FIG. 8 is a configuration diagram of the node 40.
  • These nodes 40 are, for example, three transmitting nodes arranged on the left side of FIG. 1, and four transmitting nodes arranged on the left side of FIG.
  • the node 40 includes a burst light receiving section 41, a high-speed AD conversion section 42, a waveform memory section 43, a timing control section 44, a TS (Time Slot) control section 45, a counter management section 46, and a clock section 47. , and a burst light transmitter 48.
  • the burst light receiver 41 receives burst light (burst signal) including a timing signal.
  • the high-speed AD conversion section 42 performs AD conversion on the received burst light at high speed, and notifies the waveform memory section 43 of a timing signal of the conversion result.
  • the waveform memory section 43 notifies the timing control section 44 of the waveform memory (stored timing signal) of the periodic timing signal. Therefore, the timing control section 44 controls the waveform memory section 43 to autonomously extract periodic timing signals.
  • the timing control section 44 notifies the TS control section 45 and the counter management section 46 of the reception timing obtained from (the waveform memory of) the previous timing signal. Furthermore, the timing control unit 44 grasps the current reception timing and corrects the reception timing of the timing signal stored up to the previous time. Based on the reception timing notified from the timing control unit 44, the TS control unit 45 controls the time slot in which the signal transmitted by its own device is superimposed so as not to collide with other signals.
  • the counter management section 46 notifies the timing control section 44 and the TS control section 45 of the counter value. As explained in FIG. 7, the counter value indicates the time from transmitting a timing signal to transmitting the next timing signal.
  • the clock section 47 supplies a clock to the counter management section 46 .
  • the burst light transmitter 48 superimposes an arbitrary signal on the TS designated by the TS controller 45 and transmits a data signal.
  • FIG. 9 is a sequence diagram showing details of the operation of the node 40.
  • the burst light receiving unit 41 receives burst light and converts it into an electrical signal (O/E conversion: Optical/Electrical conversion) (S111).
  • the high-speed AD converter 42 removes noise from the electrical signal (A/D conversion: Analog/Digital conversion) (S121).
  • the waveform memory section 43 notifies the timing control section 44 of the waveform memory of the electrical signal (S131).
  • the timing control unit 44 notifies the counter management unit 46 of the timing signal reception time (S141).
  • the clock section 47 supplies a clock to the counter management section 46 (S161).
  • the counter management unit 46 starts a counter based on the clock (S151).
  • the counter management unit 46 notifies the timing control unit 44 of the counter value (S152).
  • the timing control unit 44 grasps the cycle of the timing signal (S142).
  • the counter management unit 46 notifies the waveform memory unit 43 of the counter value (S153).
  • the timing control section 44 notifies the waveform memory section 43 of the next reception time (S143).
  • the burst light receiving section 41 receives the burst light and converts it into an electrical signal (S112).
  • the high-speed AD conversion unit 42 removes noise from the electrical signal (A/D conversion) (S122).
  • the waveform memory section 43 notifies the timing control section 44 of waveform memories within an arbitrary range (S132).
  • the timing control section 44 grasps the reception timing of the timing signal and notifies the counter management section 46 (S144).
  • the clock section 47 supplies the clock to the counter management section 46 (S162).
  • the counter management unit 46 corrects the counter value based on the clock (S154).
  • the timing control unit 44 notifies the TS control unit 45 of the time slot reference (reception timing) (S145).
  • the counter management unit 46 notifies the TS control unit 45 of the counter value (S156).
  • the TS control unit 45 determines the TS (time slot) on which the data signal D is superimposed (S171).
  • the burst light transmitter 48 superimposes an arbitrary signal on the TS designated by the TS controller 45 and transmits a data signal (S181).
  • FIG. 10 is a hardware configuration diagram of an optical TDM transmission device (node 40 in FIG. 8).
  • the optical TDM transmission device is configured as a computer 900 having a CPU 901, a RAM 902, a ROM 903, an HDD 904, a communication I/F 905, an input/output I/F 906, and a media I/F 907.
  • the T transmitter 30 in FIG. 7 is similarly configured as a computer 900.
  • Communication I/F 905 is connected to external communication device 915.
  • the input/output I/F 906 is connected to the input/output device 916.
  • the media I/F 907 reads and writes data from the recording medium 917.
  • the CPU 901 controls each unit by executing a program (also called an application or an abbreviated application) read into the RAM 902 .
  • This program can also be distributed via a communication line or recorded on a recording medium 917 such as a CD-ROM.
  • the present invention provides an optical TDM transmission system in which a plurality of nodes 40 transmit data signals while synchronizing time slots between the nodes.
  • Each node 40 is In the first period before superimposing the data signal, a timing signal that is periodically transmitted to each node 40 is received multiple times, and the reception time and reception period of the received timing signal are used as the reception timing of the timing signal.
  • control is performed so that the data signal transmitted from itself is superimposed on a time slot grasped based on the stored reception timing.
  • each node 40 on the transmitting side synchronizes with other nodes 40 by storing the cycle and reception time of the received timing signal as the reception timing (1-way synchronization process). ). This makes it possible to avoid collisions between signals during multiplexing in an N-to-M optical connection network without measuring RTT for each individual node 40.
  • each node 40 receives the timing signal transmitted to each node 40 even in the second period, and calculates the stored reception timing based on the reception time and reception period of the received timing signal. It is characterized by correction.
  • each node 40 to continuously adjust timing not only in the first period but also in the second period. Therefore, even in environments where the physical properties of optical fibers change due to temperature changes, etc., it is possible to maintain highly accurate time slot synchronization between nodes.

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  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Optical Communication System (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)

Abstract

Selon la présente invention, dans un système de transmission TDM optique dans lequel une pluralité de nœuds (40) transmettent des signaux de données dans un état dans lequel des créneaux temporels sont synchronisés entre les nœuds, une commande est mise en œuvre de sorte que : dans une première période de temps antérieure à la superposition de signaux de données, chacun des nœuds (40) reçoive, plusieurs fois, des signaux de synchronisation transmis de manière cyclique au nœud (40), et stocke des cycles de réception et des points temporels de réception des signaux de synchronisation reçus en tant que synchronisations de réception des signaux de synchronisation ; et, dans une seconde période de temps dans laquelle des signaux de données sont superposés, chacun des nœuds (40) amène un signal de données transmis à partir du nœud lui-même à être superposé sur un créneau temporel identifié au moyen des synchronisations de réception stockées en tant que référence.
PCT/JP2022/024086 2022-06-16 2022-06-16 Dispositif de transmission tdm optique, procédé de synchronisation, et programme de synchronisation WO2023243030A1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050117571A1 (en) * 2003-12-01 2005-06-02 Dyke Robert G. Distribution of time division multiplexed data through packet connections
CN101582734A (zh) * 2008-05-14 2009-11-18 上海贝尔阿尔卡特股份有限公司 波分复用无源光网络中的接入控制方法及其装置
WO2013187474A1 (fr) * 2012-06-13 2013-12-19 日本電信電話株式会社 Système de réseau optique, nœud de commutation optique, nœud maître et nœud

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050117571A1 (en) * 2003-12-01 2005-06-02 Dyke Robert G. Distribution of time division multiplexed data through packet connections
CN101582734A (zh) * 2008-05-14 2009-11-18 上海贝尔阿尔卡特股份有限公司 波分复用无源光网络中的接入控制方法及其装置
WO2013187474A1 (fr) * 2012-06-13 2013-12-19 日本電信電話株式会社 Système de réseau optique, nœud de commutation optique, nœud maître et nœud

Non-Patent Citations (1)

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Title
KOTA NISHIYAMA, MASAHIRO NAKAGAWA, TOSHIYA MATSUDA, KANA MASUMOTO, TAKESHI SEKI, TAKASHI MIYAMURA: "Proposal of Timing Adjustment Method to Realize High-precision Synchronization in Optical Time Division Multiplexing Transmission", IEICE TECHNICAL REPORT, PN, THE INSTITUTE OF ELECTRONICS, INFORMATION AND COMMUNICATION ENGINEERS, JP, vol. 122, no. 71 (PN2022-6), 3 June 2022 (2022-06-03), JP, pages 7 - 11, XP009551137 *

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