Method and system for dynamic bandwidth allocation in an optical access network
First Claim
1. A method of transmitting data in an optical network comprising:
- generating a table that includes information about the current sizes of data waiting to be transmitted from a plurality of remote terminals to a central terminal;
selectively transmitting grant messages to said remote terminals, each grant message being indicative of a permission for a targeted remote terminal to transmit an authorized amount of said data waiting at said targeted remote terminal, said authorized amount being dependent on said information included in said table with regard to said targeted remote terminal;
receiving authorized amounts of said data from said remote terminals in response to said grant messages, including request messages containing updated information about the current sizes of said data waiting to be transmitted at said remote terminals; and
updating said table using said updated information contained in said request messages received from said remote terminals.
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Accused Products
Abstract
An optical access network and method for transmitting optical data in the network utilizes an interleaved polling scheme to efficiently use the available bandwidth of the network. The use of the interleaved polling scheme allows a central terminal of the network to dynamically allocate upstream bandwidth from remote terminals of the network to the central terminal in response to the amount of data that is waiting at the remote terminals to be transmitted to the OLT. In one embodiment, the optical access network is based on Passive Optical Network (PON) technology. In another embodiment, the optical access network utilizes Ethernet protocol to encapsulate data in Ethernet frames for transmission. Thus, in these embodiments, the optical access network includes all of the advantages associated with the PON technology and/or the Ethernet protocol. In addition, since the allocation of upstream bandwidth is on an as needed basis, loss of bandwidth due to unfilled time slots is substantially eliminated.
187 Citations
43 Claims
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1. A method of transmitting data in an optical network comprising:
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generating a table that includes information about the current sizes of data waiting to be transmitted from a plurality of remote terminals to a central terminal;
selectively transmitting grant messages to said remote terminals, each grant message being indicative of a permission for a targeted remote terminal to transmit an authorized amount of said data waiting at said targeted remote terminal, said authorized amount being dependent on said information included in said table with regard to said targeted remote terminal;
receiving authorized amounts of said data from said remote terminals in response to said grant messages, including request messages containing updated information about the current sizes of said data waiting to be transmitted at said remote terminals; and
updating said table using said updated information contained in said request messages received from said remote terminals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
detecting a disconnected remote terminal; and
reducing the frequency of grant messages that are transmitted to said disconnected remote terminal.
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8. The method of claim 7 wherein said step of detecting said disconnected remote terminal includes waiting a predefined period for said disconnected remote terminal to respond to a grant message transmitted to said disconnected remote terminal.
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9. The method of claim 1 further comprising a step of embedding said grant messages in between Ethernet frames or within said Ethernet frames, each grant message being embedded after a code of an Ethernet frame that is not used for Ethernet encoding, said code being utilized as an escape code.
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10. The method of claim 1 wherein said authorized amount in said step of selectively transmitting said grant messages is less than a predefined maximum amount.
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11. The method of claim 1 wherein said optical network is a passive optical network.
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12. The method of claim 11 wherein said optical network is an Ethernet-based passive optical network.
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13. The method of claim 1 wherein each of said grant messages and said request messages includes an identification code field and a window size field.
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14. The method of claim 13 wherein said Window size field of each of said grant messages defines said authorized amount of data permitted to be transmitted by a receiving remote terminal.
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15. The method of claim 13 wherein said window size field of each of said request messages defines the current size of data waiting to be transmitted to said central terminal at a transmitting remote terminal.
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16. The method of claim 1 wherein said table further includes information about round trip times of data transmission between said central terminal and said remote terminals.
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17. The method of claim 16 further comprising:
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computing current round trip times for said remote terminals, including monitoring transmission times associated with said grant messages from said central terminal and reception times associated with said authorized amounts of said data from said remote terminals; and
updating said information about round trip times of data transmission using computed current round trip times.
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18. A method of transmitting optical signals in a point-to-multipoint optical network comprising:
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generating a table that contains entries of the current sizes of data waiting to be transmitted from a plurality of remote terminals to a central terminal;
transmitting a first grant message from said central terminal to a first remote terminal, said first grant message being indicative of a permission for said first remote terminal to transmit a specific amount of data waiting at said first remote terminal, said specific amount being dependent on an entry included in said table for said first remote terminal;
receiving said specific amount of said data from said first remote terminal at said central terminal in response to said first grant message, including a first request message containing updated information about the current size of said data waiting at said first remote terminal when said first request message was sent; and
updating said table using said updated information contained in said first request message received from said first remote terminal. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
transmitting a second grant message from said central terminal to a second remote terminal;
receiving an authorized amount of said data from said second remote terminal at said central terminal, including a second request message containing updated information about the current size of said data waiting at said second remote terminal when said second request message was sent;
updating said table using said updated information contained in said second request message received from said second remote terminal.
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20. The method of claim 19 further comprising a step of scheduling transmission times for said first and second grant messages such that said data and said first request message from said first remote terminal do not collide with said data and said second request message from said second remote terminal during transmission, said transmission times for said first and second grant messages substantially defining reception times for said first request message and said second request message at said central terminal.
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21. The method of claim 20 wherein said step of scheduling said transmission times includes scheduling said transmission times such that said first grant message to said first remote terminal is not transmitted before a previous request message from said first remote terminal is received by said central terminal.
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22. The method of claim 20 wherein said step of scheduling said transmission times includes rescheduling an original transmission time for said first grant message to a rescheduled transmission time when said original transmission time conflicts with another transmission time for a different grant message.
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23. The method of claim 22 wherein said step of rescheduling includes rescheduling said original transmission time for said first grant message such that said rescheduled transmission time is after said different grant message has been transmitted.
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24. The method of claim 18 further comprising;
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detecting a disconnected remote terminal; and
reducing the frequency of grant messages that are transmitted to said disconnected remote terminal.
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25. The method of claim 24 wherein said step of detecting said disconnected remote terminal includes waiting a predefined period for said disconnected remote terminal to respond to a grant message transmitted to said disconnected remote terminal.
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26. The method of claim 18 wherein said step of updating said table includes subtracting a value from a new entry for said first remote terminal, said value corresponding to an actual amount of data transmitted from said first remote terminal, said new entry corresponding to said updated information contained in said first request message from said first remote terminal.
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27. The method of claim 18 further comprising a step of embedding said first grant message in between Ethernet frames or within one of said Ethernet frames, said first grant message being embedded after a code of an Ethernet frame that is not used for Ethernet encoding, said code being utilized as an escape code.
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28. The method of claim 18 wherein said specific amount in said step of transmitting said first grant message is less than a predefined maximum amount.
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29. The method of claim 18 wherein said point-to-multipoint optical network is an Ethernet-based passive optical network.
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30. The method of claim 18 wherein said table further includes information about round trip times of data transmission between said central terminal and said remote terminals.
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31. The method of claim 30 further comprising:
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computing a current round trip time for said first remote terminal, including monitoring a transmission time associated with said first grant message from said central terminal and a reception time associated with said specific amount of said data from said first remote terminal; and
updating said information about round trip times of data transmission for said first remote terminal using a computed current round trip time.
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32. A point-to-multipoint optical network comprising:
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a plurality of remote terminals that receive and transmit optical data, each remote terminal configured to transmit a request message and an authorized amount of data waiting at said remote terminal in response to a grant message received by said remote terminal, said request message including updated information about the current size of data waiting at said remote terminal, said grant message including information that indicates said authorized amount; and
a central terminal optically coupled to said remote terminals to transmit and receive said optical data, said central terminal comprising;
memory that includes a table containing latest information about the current sizes of data waiting to be transmitted from said remote terminals to said central terminal; and
a processor that is configured to selectively transmit grant messages to said remote terminals using said latest information contained in said table to indicate authorized amounts of data that can be sent by receiving remote terminals, said processor further configured to receive request messages from said remote terminals in response to said grant messages and to update said table in said memory using said updated information contained in said request messages. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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Specification