WO2009124476A1 - Procédé et appareil pour étendre le nombre d'unités de réseau optique dans un réseau optique passif - Google Patents

Procédé et appareil pour étendre le nombre d'unités de réseau optique dans un réseau optique passif Download PDF

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Publication number
WO2009124476A1
WO2009124476A1 PCT/CN2009/070966 CN2009070966W WO2009124476A1 WO 2009124476 A1 WO2009124476 A1 WO 2009124476A1 CN 2009070966 W CN2009070966 W CN 2009070966W WO 2009124476 A1 WO2009124476 A1 WO 2009124476A1
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WIPO (PCT)
Prior art keywords
onu
field
frame
optical network
additional
Prior art date
Application number
PCT/CN2009/070966
Other languages
English (en)
Inventor
Yuanqiu Luo
Frank J. Effenberger
Original Assignee
Huawei Technologies Co., Ltd.
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 Huawei Technologies Co., Ltd. filed Critical Huawei Technologies Co., Ltd.
Publication of WO2009124476A1 publication Critical patent/WO2009124476A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • 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]
    • H04L12/2854—Wide area networks, e.g. public data networks
    • H04L12/2856—Access arrangements, e.g. Internet access
    • H04L12/2858—Access network architectures
    • H04L12/2861—Point-to-multipoint connection from the data network to the subscribers
    • 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]
    • H04L12/2854—Wide area networks, e.g. public data networks
    • H04L12/2856—Access arrangements, e.g. Internet access
    • H04L12/2869—Operational details of access network equipments
    • H04L12/2878—Access multiplexer, e.g. DSLAM
    • H04L12/2879—Access multiplexer, e.g. DSLAM characterised by the network type on the uplink side, i.e. towards the service provider network
    • H04L12/2885—Arrangements interfacing with optical systems
    • 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]
    • H04L12/2854—Wide area networks, e.g. public data networks
    • H04L12/2856—Access arrangements, e.g. Internet access
    • H04L12/2869—Operational details of access network equipments
    • H04L12/2898—Subscriber equipments
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q11/0066—Provisions for optical burst or packet networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q11/00—Selecting arrangements for multiplex systems
    • H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
    • H04Q11/0062—Network aspects
    • H04Q2011/009—Topology aspects

Definitions

  • the present invention relates to a Passive Optical Network, and particularly to the extension of Optical Network Unit amount in a Gigabit Passive Optical Network (G-PON) or a Next Generation Access (NGA).
  • G-PON Gigabit Passive Optical Network
  • NGA Next Generation Access
  • PON Passive Optical Networks
  • a PON typically includes one Optical Line Terminal (OLT) and a plurality of Optical Network Units (ONU) or Optical Network Terminals (ONT).
  • Fig. 1 shows an example of a PON system, in which one OLT 101 is connected to three ONUs 102a to 102c through a passive element, i.e., an Optical Splitter 103.
  • OLT 101 is located at the service provider's central office and plays central role in providing information to subscribers.
  • ONUs 102a to 102c are located near subscribers to communicate with them.
  • OLT 101 broadcasts downstream frames to ONUs 102a to 102c via Optical Splitter 103.
  • the downstream frames are first transmitted to Optical Splitter 103 via a single feeder fiber, and then are distributed to ONUs via multiple distribution fibers.
  • Optical Splitter 103 multiplexes upstream frames received from ONUs 102a to 102c, and transmits the multiplexed frame to OLT 101.
  • the PON as illustrated in Fig. 1, has been enhanced to have a bandwidth up to 2.488 Gbps symmetrically, as defined in the International Telecommunication Union Standardization Sector (ITU-T) G-PON standard. Furthermore, the PON bandwidth efficiency has been improved through the use of G-PON Encapsulation Method (GEM).
  • GEM G-PON Encapsulation Method
  • the NGA architecture includes Next Generation PONs (XG-PONs), in which the downstream bandwidth is 10 Gbps and the upstream bandwidth is at least 2.5 Gbps. This situation represents a further enhancement of PON bandwidth, so that the NGA system targets to serve a larger amount of ONUs.
  • XG-PONs Next Generation PONs
  • the great bandwidth of a G-PON or NGA indicates that there is a possibility to accommodate a large number of ONUs, or to serve more and more subscribers in such a PON system. This just meets the most operators' objective. Therefore, attention has turned towards how to accommodate more ONUs in a PON system.
  • ONU- ID ONU identifier
  • the 1-byte field upper-bounds the total number of ONUs in a G- PON by the value of 256, which is much less than a desirable value for representing the large amount of ONUs in today's G-PON or NGA.
  • GTC G-PON Transmission Convergence
  • An object of present invention is to allow service for more ONUs in a G-PON or NGA system. Another object of present invention is to allow service for more ONUs without making much changes to the current G-PON or NGA system. To this end, embodiments of present invention are provided as bellows.
  • a method for transmitting information in a passive optical network which has an Optical Line Terminal (OLT) and a plurality of Optical Network Units (ONU) comprises steps of: constructing a Transmission Convergence (TC) frame having a frame header, wherein the frame header includes one ONU-ID field and at least one additional ONU-ID field that occupies reserved bits and/or deprecated fields in the frame header, the ONU- ID field and the at least one additional ONU-ID field are combined to identify one ONU in the passive optical network; transmitting the constructed TC frame.
  • TC Transmission Convergence
  • an apparatus for transmitting information in a passive optical network which includes an Optical Line Terminal (OLT) and a plurality of Optical Network Units (ONU)
  • a framer adapted to construct a Transmission Convergence (TC) frame having a frame header, wherein the frame header includes one ONU-ID field and at least one additional ONU-ID field occupying reserved bits and/or deprecated fields in the frame header, and the ONU-ID field and the at least one additional ONU-ID field are combined to identify one ONU; and a transmitter adapted to transmit the constructed TC frame.
  • TC Transmission Convergence
  • a method for receiving information in a passive optical network which includes an Optical Line Termination (OLT) and a plurality of Optical Network Units, comprises steps of: receiving a Transmission Convergence (TC) frame having a frame header; extracting bits from one ONU-ID field and at least one additional ONU-ID field in the frame header; combining the extracted bits to identify one ONU addressed in the TC frame; wherein the at least one additional ONU-ID field occupies reserved bits and/or deprecated fields in the frame header.
  • TC Transmission Convergence
  • the Optical Network Unit (ONU) for receiving information from an Optical Line Termination (OLT) in a passive optical network comprises: a receiver to receive a Transmission Convergence (TC) frame having a frame header transmitted from the OLT to a target ONU; a processor to extract bits from one ONU-ID field and at least one additional ONU-ID field in the frame header, and combine the extracted bits to identify the target ONU of the TC frame; wherein the at least one additional ONU-ID field occupies reserved bits and/or deprecated fields in the frame header.
  • TC Transmission Convergence
  • a Transmission Convergence (TC) frame structure for transmitting information in a passive optical network having an Optical Line Terminal (OLT) and a plurality of Optical Network Units (ONUs), comprises : a frame header, wherein the frame header includes one ONU-ID field and at least one additional ONU-ID field that occupies reserved bits and/or deprecated fields in the frame header, and the ONU-ID field and the at least one additional ONU-ID field are combined to identify one ONU.
  • FIG. 1 is a block diagram of a PON system
  • Fig. 2 shows the structure of a GTC frame
  • FIG. 3 shows the detailed structure of US BW Map field
  • Fig. 4 illustrates a G-PON with multiple upstream wavelengths
  • Fig. 5 shows a structure of PCBd according to an embodiment of present invention.
  • an upstream frame to an OLT is not required to include an ONU-ID, because the OLT works as the master in the G-PON system and arbitrates all upstream transmissions in advance.
  • ONU since the downstream transmission in a G-PON system is broadcast in nature, ONU must identify the recipient ONU (or target ONU) of a downstream frame, and then capture the data of the downstream frame destined for itself address and discard all of other frames. Therefore, the following embodiments focus on the downstream transmission in a PON system. But, it can be understood that an upstream frame may also contain an ONU ID in the same way as a downstream frame does if necessary.
  • Fig. 1 illustrates an exemplary structure of a GTC frame for the downstream direction.
  • a GTC frame consists of a Physical Control Block downstream (PCBd) as a frame header, and Payload for downstream.
  • PCBd Physical Control Block downstream
  • the PCBd contains several fields for management control of transmissions.
  • Each of ONUs 102a to 102c receives the entire PCBd, and acts upon the relevant information contained therein.
  • a 13 -byte PLOAMd Physical Layer Operations, Administration and Maintenance downstream field is adapted to carry GTC messages related to OAM alarms, threshold-crossing alerts triggered by events or all activation related messages, such as assigning an ONU ID for a new ONU.
  • the GTC message structure is also illustrated in Fig. 2.
  • a GTC message includes a 1-byte ONU-ID field to addresses a particular ONU.
  • each ONU reads the ONU ID in the ONU-ID field to determine whether the downstream frame is targeted to itself.
  • the ONU ID is typically a number from O to 254 assigned by the OLT.
  • the ONU-ID field is set to OxFF.
  • This 1- byte field upper-bounds the total number of ONUs in a G-PON by the value of 256, which is much less than the desirable amount of ONUs in today's or future G-PON or NGA. Thus, there is a need to extend ONU amount.
  • the US BW map field is a scalar array of 8 byte allocation structures. Each entry in this array represents a single bandwidth allocation of a particular Transmission Container (T-CONT).
  • T-CONT Transmission Container
  • the format of each entry is illustrated in Fig. 3. As shown in Fig. 3, each entry includes an Alloc-ID field.
  • the Alloc-ID field contains a 12-bit number that indicates the particular T-CONT that is being granted time on the upstream of the PON. This means the maximum amount of T-CONTs in a G-PON is 4096.
  • each ONU may be assigned to one or more T-CONTs for data transmission.
  • Current implementations tend towards assigning 5 T-CONTs per ONU, targeting to carry 5 types of T-CONTs defined in the G-PON standard. Therefore, the Alloc-ID field gives the provisioning of enough T-CONTs for about 810 ONUs.
  • the number of bits for an ONU ID is required to be extended, so that the G-PON or NGA system can accommodate more than 256 ONUs.
  • a straight-forward way to increase the ONU amount relies on extending the ONU-ID field length in a downstream frame directly.
  • the 1-byte ONU- ID field needs to be extended to at least 10 bits.
  • the 10-bit ONU-ID field gives the maximum amount of 1024, which matches the amount of T-CONTs supported by GTC.
  • the extension of ONU-ID field might result in major changes to the current GTC frame. The changes include at least the modifications in PLOAM message and GTC upstream frame structure.
  • this embodiment is more adaptable to a simple or dedicated GPON or NGA.
  • Another way to increase the ONU amount is to utilize one or more reserved bits or deprecated fields in a GTC frame as an additional ONU-ID field.
  • the additional ONU-ID filed may be combined with the original ONU-ID field of PLOAMd to identify a unique ONU in a G- PON.
  • Figs. 4 and 5 show the specific embodiments of this method.
  • Fig. 4 shows an embodiment of present invention, in which ONUs are divided into several groups and identified by both original ONU IDs and their group identifier.
  • the GPON system utilizes multiple wavelengths to carry upstream frames.
  • ONU 502a and ONU 502b transmit upstream frames to OLT 501 at wavelength I, e.g. 1310nm
  • ONU 502c and ONU 502d use wavelength II, e.g. 1550nm, to transmit upstream frames.
  • four ONUs may be divided into two groups, and each group corresponds to one working upstream wavelength. That is, Group I includes ONU 502a and 502b, Group II includes ONU 502c and 502d.
  • each upstream wavelength represents a physically independent group of ONUs.
  • a group identifier for ONU is added into the PCBd of GTC downstream frame.
  • Some reserved bits or deprecated fields in the PCBd may be used to represent the group identifier.
  • the bits for representing the group identifier may be called as the additional ONU-ID field.
  • the reserved bit in IDENT field of PCBd can be employed to carry the group identifier.
  • the 12-bit Alen (Asynchronous Transfer Mode (ATM) partition length) field in PLend (Payload lengh dowstream) field of PCBd which is dedicated to the deprecated Asynchronous Transfer Mode (ATM) partition, may be another option to carry the group identifier.
  • the Alen filed may be incorporated with the IDENT filed to represent the group identifier.
  • the present invention is not limited to this, the reserved bits in other fields or other deprecated fields in PCBd may be also served as the additional ONU- ID field to represent the group identifier.
  • the group identifier carried in the additional ONU-ID filed may be combined with the ONU ID in the original ONU-ID field to identify a recipient ONU (or target ONU) of a downstream frame. For example, if the group identifier in a downstream frame indicates Group II, and the ONU ID is 0x02, it can be determined that the target ONU of the downstream frame is the ONU 502d of Fig. 4.
  • Another embodiment to increase the ONU amount is to separate an ONU ID into at least two parts, one part is contained in the original ONU-ID field, and others are contained in at least one additional ONU-ID filed as shown in Fig. 5.
  • each ONU is assigned with a unique ONU ID, which may have more than 8 bits, e.g. 12bits.
  • This unique ONU ID may be separated into at least two sub-fields for ONU ID.
  • One sub-field is the original ONU-ID field, i.e., including 8 bits of the ONU ID, and the other may be located in other fields in PCBd (i.e. the additional ONU-ID field).
  • the remaining bits e.g.
  • 4 bits may be included in IDENT field, Alen filed of PLend, or the combination thereof, as mentioned above.
  • the bits in all of the sub-fields for ONU ID are extracted and combined together to restore the unique ONU ID, i.e. the target ONU ID of the downstream frame.
  • ONU amount is extended by using at least one additional ONU-ID field that occupies the reserved bits or deprecated fields in a frame header of a GTC frame. This minimizes the changes to the current GTC by maintaining the fundamental structures, and benefits the accommodation of a large amount of ONUs.
  • an OLT includes, among others, a framer for constructing a downstream frame and a transmitter for transmitting the constructed downstream frames to ONUs.
  • the framer of OLT constructs a downstream frame with a frame header in accordance with Fig. 5, that is, the frame header includes an ONU-ID field in PLOAMd, and at least an additional ONU-ID fields in the reserved bits or deprecated fields in the frame header, e.g., IDENT or PLend fields.
  • the ONU-ID field and the additional ONU-ID fields may be combined to identify a target ONU of the downstream frame.
  • ONU includes, among others, a receiver for receiving a downstream frame from the OLT, and a processor to extract the ONU ID from the received downstream frame and determine to capture the payload of the received downstream frame if the frame is targeted to itself.
  • the processor of ONU extracts bits from not only the ONU-ID field of PLOAMd but also from at least one additional ONU-ID fields, e.g. IDENT or PLend fields, and combine the extracted information to identify the target ONU of the received downstream frame, as mentioned above. In this way, each ONU may recognize the downstream frames destined for its address, and the total number of ONUs may exceed 256.
  • the mechanism disclosed above is not limited to the downstream transmission, but may be applied to upstream transmission if necessary.
  • the additional ONU-ID field may occupy the reserved bits or deprecated fields in the frame header of the upstream frame.
  • ONU may include a framer and a transmitter similar to those of OLT for downstream transmission
  • OLT may include a receiver and a processor similar to those of ONU for downstream transmission.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Small-Scale Networks (AREA)

Abstract

L'invention porte sur un mécanisme pour étendre le nombre de réseaux optiques (ONU) dans un réseau optique passif (PON). Le mécanisme étend la quantité ONU par utilisation des bits réservés ou des champs dépréciés dans un en-tête de trame d'une trame de convergence de transmission d'au moins un champ ONU-ID supplémentaire, ledit au moins un champ ONU-ID supplémentaire et le champ ONU-ID initial étant combinés pour identifier un des ONU. Ce mécanisme permet une mise à niveau rapide de système PON courant pour servir plus d'ONU.
PCT/CN2009/070966 2008-04-07 2009-03-24 Procédé et appareil pour étendre le nombre d'unités de réseau optique dans un réseau optique passif WO2009124476A1 (fr)

Applications Claiming Priority (2)

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US4301108P 2008-04-07 2008-04-07
US61/043,011 2008-04-07

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102056031A (zh) * 2009-11-10 2011-05-11 华为技术有限公司 传输多路业务的方法和装置
US10389471B2 (en) * 2011-04-08 2019-08-20 Futurewei Technologies, Inc. Wavelength indication in multiple-wavelength passive optical networks

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070166037A1 (en) * 2006-01-06 2007-07-19 Paparao Palacharla System and Method for Managing Network Components in a Hybrid Passive Optical Network

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070166037A1 (en) * 2006-01-06 2007-07-19 Paparao Palacharla System and Method for Managing Network Components in a Hybrid Passive Optical Network

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
INTERNATIONAL TELECOMMUNICATION UNION: "Gigabit-capable Passive Optical etworks (G-PON): Transmission convergence layer specification", ITU-T G.984., 3 February 2004 (2004-02-03), pages 22 - 55 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102056031A (zh) * 2009-11-10 2011-05-11 华为技术有限公司 传输多路业务的方法和装置
CN102056031B (zh) * 2009-11-10 2013-12-04 华为技术有限公司 传输多路业务的方法和装置
US8824498B2 (en) 2009-11-10 2014-09-02 Huawei Technologies Co., Ltd. Method and apparatus for transmitting multiple services
US10389471B2 (en) * 2011-04-08 2019-08-20 Futurewei Technologies, Inc. Wavelength indication in multiple-wavelength passive optical networks
US10623127B2 (en) 2011-04-08 2020-04-14 Futurewei Technologies, Inc. Wavelength indication in multiple-wavelength passive optical networks

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