Method for implementing various functions in gigabit ethernet-passive optical network system and structure of ethernet frame employed in the same

• US 20030133460A1
• Filed: 11/27/2002
• Published: 07/17/2003
• Est. Priority Date: 01/17/2002
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Park, Tae-Sung, Choi, Do-In, Jang, Soon-Ho, Kim, Su-Hyung, Sung, Whan-Jin, Won, Shin-Hee, Lee, Min-Hyo
• Granted Patent: US 7,289,439 B2
• Time in Patent Office: Days
• US Class Current: 370/395.43
• CPC Class Codes: H04J 3/0682 by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging
• CPC Class Codes: H04L 12/2801 Broadband local area networks
• CPC Class Codes: H04Q 11/0066 Provisions for optical burst or packet networks
• CPC Class Codes: H04Q 11/0067 Provisions for optical access or distribution networks, e.g. Gigabit Ethernet Passive Optical Network (GE-PON), ATM-based Passive Optical Network (A-PON), PON-Ring
• CPC Class Codes: H04Q 11/0071 Provisions for the electrical-optical layer interface
• CPC Class Codes: H04Q 2011/0079 Operation or maintenance aspects
• CPC Class Codes: H04Q 2011/0088 Signalling aspects

Abstract

A GE-PON (Gigabit Ethernet-Passive Optical Network) system is provided that configures upstream and downstream frames on the basis of a variable-length Ethernet frame. The GE-PON system employs TDM (Time Division Multiplexing) for upstream packet transmission in a tree structure for a point-to-multipoint connection. A structure of a frame format is also provided that is capable of effectively accommodating Gigabit Ethernet traffic in the GE-PON system and a method is provided for implementing various functions such as initial ONU registration, late ONU registration, ranging, and dynamic bandwidth allocation in the GE-PON system.

Claims

1. A method for implementing various functions in a GE-PON (Gigabit Ethernet-Passive Optical Network) system, the method comprising the steps of:

a) periodically transmitting, by an OLT(Optical Line Termination), synchronous signals to the ONUs (Optical Network Units) after initial drive such that each of a plurality of ONUs is synchronized with the OLT in response to one of the synchronous signals periodically transmitted;

b) identifying, by the ONU synchronized with the OLT, a transmission start time of an initial registration request frame and a transmission time length included in a grant frame such that the ONU transmits the initial registration request frame to the OLT after a random delay in order to avoid collision of initial registration request frames transmitted from the ONUs at a transmission time of the initial registration request frame;

c) calculating, by the OLT receiving the initial registration request frame, a difference between a predicted frame arrival time and a real frame arrival time, the predicted frame arrival time being predicted from the transmission start time of the initial registration request frame indicated in the grant frame such that the OLT calculates an RTT (Round Trip Time) with a random delay value; and

d) registering, by the OLT of the ONU requesting an ONU registration, in an ONU list after calculation of the RTT such that the OLT gives a new ONU ID to the ONU, and transmits a registration response frame including the new ONU ID and the RTT to the ONU requesting the ONU registration.

2. The method as set forth in claim 1, further comprising the step of:

e) using the RTT included in the registration response frame by the ONU receiving the registration response frame to correct a synchronous error due to a DD (Downstream Delay) and a UD (Upstream Delay).

3. The method as set forth in claim 1, further comprising the step of:

f) before identification of the transmission start time of the initial registration request frame and the transmission time length included in the grant frame, determining by the ONU whether a value of a grant type field is set to a value indicating a grant of the initial registration request.

4. The method as set forth in claim 1, wherein the initial registration request frame includes an Ethernet MAC (Medium Access Control) hardware address identifying the ONU requesting the ONU registration as a temporary ONU ID.

5. The method as set forth in claim 1, wherein the RTT has a value of (the real frame arrival time—

the predicted frame arrival time—

the random delay value).

6. A method for implementing a plurality of functions in a GE-PON (Gigabit Ethernet-Passive Optical Network) system,the method comprising the steps of:

a) transmitting and receiving data by an OLT (Optical Line Termination) and a plurality of ONUs(Optical Network Units), in synchronization with the OLT on the basis of synchronous signals;

b) synchronizing at least one ONU, newly driven among the ONUs, with a synchronous signal of downstream transmission;

c) identifying by the ONU in synchronization with the synchronous signal a transmission start time of a late registration request frame and a transmission time length included in a grant frame such that the ONU transmits the late registration request frame to the OLT at a transmission time of the late registration request;

d) calculating by the OLT receiving the late registration request frame a difference between a predicted frame arrival time and a real frame arrival time, the predicted frame arrival time being predicted from the transmission start time of the late registration request frame indicated in the grant frame such that the OLT calculates an Round Trip Time (RTT) with a random delay value; and

e) registering, by the OLT, the ONU requesting a late ONU registration in an ONU list after calculation of the RTT, wherein the OLT gives a new ONU ID to the ONU, and transmits a registration response frame that comprises the new ONU ID and the RTT to the ONU requesting the late ONU registration.

7. The method as set forth in claim 6, further comprising the steps of:

f) correcting by the ONU that receives the registration response frame a synchronous error due to a DD (Downstream Delay) and a UD (Upstream Delay) with the RTT included in the registration response frame; and

g) if the ONU does not receive the registration response frame, the ONU conducting the steps of—

i. re-transmitting the late registration request frame a predetermined number of times for its own late registration with a random back-off algorithm,

ii. receiving a late registration grant frame, and

iii. performing upstream transmission of the late registration request frame.

8. A method for implementing a plurality of functions in a GE-PON (Gigabit Ethernet-Passive Optical Network) system, the method comprising the steps of:

a) transmitting by the OLT(Optical Line Termination) grant frames to a plurality of ONUs(Optical Network Units), in order to correct an error caused by an external variation, each grant frame comprising information relating to an ID of an ONU having a ranging opportunity, a grant start time and a grant time length;

b) transmitting by the ONU receiving the grant frame a ranging request frame to the OLT at a next ranging grant start time; and

c) calculating by the OLT receiving the ranging request frame an error using a difference between a predicted frame arrival time and a real frame arrival time, the predicted frame arrival time being predicted from the transmission start time of the ranging request frame indicated in the grant frame such that the OLT transmits the ranging response frame comprising an error correction value based on the calculated error to the ONU requesting ranging.

9. The method as set forth in claim 8, further comprising the step of:

d) performing by the ONU receiving the grant frame a precision correction of the error caused by an external variation using the error correction value included in the grant frame.

10. A method for implementing a plurality of functions in a GE-PON (Gigabit Ethernet-Passive Optical Network) system, the method comprising the steps of:

a) transmitting by the OLT (Optical Line Termination) grant frames to a plurality of ONUs(Optical Network Units), in order to grant a bandwidth allocation request, each grant frame comprising information relating to the number of registered ONUs, an ID of an ONU having a bandwidth request opportunity, a periodic ranging correction value, a grant time offset and a transmission time length;

b) transmitting by the ONU receiving the grant frame a bandwidth allocation request frame comprising information relating to a size of buffers on transmission standby at a next bandwidth allocation request time to the OLT; and

c) after transmission of the bandwidth allocation request frame, transmitting by the ONU receiving the grant frame data on the transmission standby for the transmission time length on the basis of the transmission time length information to the OLT.

11. A structure of a variable-length Ethernet frame to be transmitted between an OLT (Optical Line Termination) and a plurality of ONUs (Optical Network Units) in a GE-PON (Gigabit Ethernet-Passive Optical Network) system, comprising:

an SOP (Start Of Packet) field in which information indicating a start of a packet is recorded;

a packet type field in which information necessary for identifying a type of packet is recorded;

a PON (Passive Optical Network) header content field in which PON header contents according to the type of packet are recorded; and

a PDU (Packet Data Unit) field in which packet data according to the type of the packet is recorded.

12. The structure as set forth in claim 11, wherein the type of the packet comprises an Ethernet PDU packet, an ATM-PDU (Asynchronous Transfer Mode-Passive Optical Network) packet and a PON dedicated packet for accommodating PON functions.

13. The structure as set forth in claim 12, wherein the PON header content field for a packet type corresponding to an Ethernet PDU comprises:

a null data field;

an ONU ID field in which an ONU ID indicating a destination of the packet is recorded when an OLT transmits a downstream packet and an ONU ID indicating a source of each packet is recorded when the plurality of ONUs, transmit upstream packets;

a length field in which total length information including an Ethernet PDU length and a header length is recorded; and

an HCS (Head Check Sum) field in which information for a header error check, except for the Ethernet PDU, is recorded.

14. The structure as set forth in claim 12, wherein the PON header content field for a packet type corresponding to an ATM-PDU comprises:

a null data field;

an ONU ID field in which an ONU ID indicating a destination of the packet is recorded when the OLT transmits a downstream packet and an ONU ID indicating a source of each packet is recorded when the ONUs transmit upstream packets;

a length field in which total length information including an ATM-PDU length and a header length is recorded; and

an HCS (Head Check Sum) field in which information for a header error check, except for the ATM-PDU, is recorded.

15. A structure of a registration request frame for a registration request among PON-function control frames to be transmitted between an OLT (Optical Line Termination) and a plurality of ONUs (Optical Network Units) in a GE-PON (Gigabit Ethernet-Passive Optical Network) system, comprising:

an SOP (Start Of Packet) field in which information indicating a start of a packet is recorded;

a packet type field in which information necessary for identifying a type of packet is recorded;

a control type field in which control type information necessary for performing a PON function is recorded;

a temporary ONU ID field in which a temporary ONU ID is recorded when ONU registration is requested;

a random delay field in which random delay information is recorded so that collision between ONU registration request packets is avoided; and

an HCS (Head Check Sum) field in which information for CRC (Cyclic Redundancy Check) is recorded so that an error in the registration request frame is checked.

16. The structure as set forth in claim 15, wherein the temporary ONU ID has an Ethernet MAC (Medium Access Control) hardware address.

17. The structure as set forth in claim 15, wherein the random delay information recorded in the random delay field is a null data value when late registration is requested.

18. A structure of a registration response frame for a registration response among PON-function control frames to be transmitted between an OLT (Optical Line Termination) and a plurality of ONUs (Optical Network Units) in a GE-PON (Gigabit Ethernet-Passive Optical Network) system, comprising:

an SOP (Start Of Packet) field in which information indicating a start of a packet is recorded;

a packet type field in which information necessary for identifying a type of packet is recorded;

a control type field in which control type information necessary for performing a PON function is recorded;

a temporary ONU ID field in which a temporary ONU ID is recorded when ONU registration is requested;

a registration ONU ID field in which a new ONU ID given by the OLT is recorded;

an RTT (Round Trip Time) field in which a round trip time between the OLT and a corresponding ONU is recorded; and

an HCS (Head Check Sum) field in which information for CRC (Cyclic Redundancy Check) is recorded so that an error in the registration response frame is checked.

19. A structure of a ranging request frame for a ranging request among PON-function control frames to be transmitted between an OLT (Optical Line Termination) and a plurality of ONUs (Optical Network Units) in a GE-PON (Gigabit Ethernet-Passive Optical Network) system, comprising:

an SOP (Start Of Packet) field in which information indicating a start of a packet is recorded;

a packet type field in which information necessary for identifying a type of packet is recorded;

a control type field in which control type information necessary for performing a PON function is recorded;

an ONU ID field in which an ID of an ONU requesting ranging is recorded; and

an HCS (Head Check Sum) field in which information for CRC (Cyclic Redundancy Check) is recorded so that an error in the ranging request frame is checked.

20. A structure of a ranging response frame for a ranging response among PON-function control frames to be transmitted between an OLT (Optical Line Termination) and a plurality of ONUs (Optical Network Units) in a GE-PON (Gigabit Ethernet-Passive Optical Network) system, comprising:

an SOP (Start Of Packet) field in which information indicating a start of a packet is recorded;

a packet type field in which information necessary for identifying a type of packet is recorded;

a control type field in which control type information necessary for performing a PON function is recorded;

an ONU ID field in which an ID of an ONU requesting ranging is recorded;

an error correction value field in which an error correction value is recorded after the ranging; and

an HCS (Head Check Sum) field in which information for CRC (Cyclic Redundancy Check) is recorded so that an error in the ranging response frame is checked.

21. A structure of a bandwidth allocation request frame for a bandwidth allocation request among PON-function control frames to be transmitted between an OLT (Optical Line Termination) and a plurality of ONUs (Optical Network Units) in a GE-PON (Gigabit Ethernet-Passive Optical Network) system, comprising:

an SOP (Start Of Packet) field in which information indicating a start of a packet is recorded;

a packet type field in which information necessary for identifying a type of packet is recorded;

a control type field in which control type information necessary for performing a PON function is recorded;

an ONU ID field in which an ID of an ONU requesting bandwidth allocation is recorded;

a queue length field in which information indicating a size of buffers on transmission standby in the ONU requesting the bandwidth allocation is recorded; and

an HCS (Head Check Sum) field in which information for CRC (Cyclic Redundancy Check) is recorded so that an error in the bandwidth allocation request frame is checked.

22. A structure of a grant frame for granting an opportunity to transmit upstream data among PON-function control frames to be transmitted between an OLT (Optical Line Termination) and a plurality of ONUs (Optical Network Units) in a GE-PON (Gigabit Ethernet-Passive Optical Network) system, comprising:

an SOP (Start Of Packet) field in which information indicating a start of a packet is recorded;

a packet type field in which information necessary for identifying a type of packet is recorded;

a control type field in which control type information necessary for performing a PON function is recorded;

a field in which information indicating the number of ONUs to which the OLT grants the opportunity to transmit the upstream data is recorded;

an ONU ID field in which an ID of an ONU receiving the grant frame is recorded;

a grant type field in which grant type information is recorded;

a grant time offset field in which information indicating a point when an ONU starts data transmission is recorded;

a grant time length field in which information indicating a transmission time length is recorded;

a periodic ranging correction value field in which a periodic ranging correction value is recorded; and

an HCS (Head Check Sum) field in which information for CRC (Cyclic Redundancy Check) is recorded so that an error in the grant frame is checked.

23. A structure of an OAM (Operations, Administration and Maintenance) frame among PON-function control frames to be transmitted between an OLT (Optical Line Termination) and a plurality of ONUs (Optical Network Units) in a GE-PON (Gigabit Ethernet-Passive Optical Network) system, comprising:

an SOP (Start Of Packet) field in which information indicating a start of a packet is recorded;

a packet type field in which information necessary for identifying a type of packet is recorded;

a control type field in which control type information necessary for performing a PON function is recorded;

an OAM content field in which OAM contents are recorded; and

an HCS (Head Check Sum) field in which information for CRC (Cyclic Redundancy Check) is recorded so that an error in the OAM frame is checked.