Flow-subcarrier mapping in optical orthogonal frequency division multiplexing

1. A method of transmitting data over a communication network, wherein a plurality of data flows are carried by respective subcarriers using orthogonal frequency division multiplexing, the method comprising:

classifying each of a plurality of data flows as having a respective data flow type;

assigning each data flow to one of a plurality of subcarrier groups, based on the data flow's type, wherein each subcarrier group comprises a respective plurality of subcarriers;

transmitting first data flows assigned to a first subcarrier group exclusively on respective subcarriers in the first subcarrier group; and

transmitting second data flows assigned to a second subcarrier group together on all of the subcarriers in the second subcarrier group;

wherein flow-subcarrier mapping (FSM) with said transmitting steps includes following constraints:

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where R denotes data rate, M denotes optical OFDM subcarriers, N denotes traffic flows, λ is related to traffic intensity, ij denoting i th data flow mapped to j th subcarrier and Pi,j denoting percentage of i th data flow's traffic that is assigned to j th subcarrier.

2. The method of claim 1 , wherein: the communication network comprises an optical network.

3. The method of claim 2 , wherein the communication network comprises at least one of an in access/metro optical network, a home optical network, a core optical network, and a virtual passive optical network.

4. The method of claim 1 , wherein the step of classifying each of a plurality of data flows as having a respective data flow type further comprises:

classifying each data flow based at least in part on whether or not the data flow has a predictable data rate.

5. The method of claim 4 , wherein the step of classifying each of a plurality of data flows as having a respective data flow type further comprises: classifying each data flow based at least in part on whether or not the data flow needs protection.

6. The method of claim 5 , wherein the step of classifying each of a plurality of data flows as having a respective data flow type further comprises:

classifying each data flow as having a data flow type selected from: a first data flow type that does not have a predictable data rate and needs protection, a second data flow type that has a predictable data rate and needs protection, a third data flow type that has a predictable data rate and does not need protection, and a fourth data flow type that does not have a predictable data rate and does not need protection.

7. The method of claim 6 , wherein the step of assigning each data flow to one of a plurality of subcarrier groups further comprises:

assigning data flows of the first data flow type to the first subcarrier group;

assigning data flows of the second and third data flow types to the second subcarrier group; and

assigning data flows of the fourth data flow type to a third subcarrier group.

8. The method of claim 7 , further comprising:

transmitting third data flows assigned to the third subcarrier together on all of the subcarriers in the third subcarrier group.

9. The method of claim 8 , further comprising re-assigning a subcarrier that is not in the first subcarrier group to the first subcarrier group when the subcarrier becomes idle.

10. The method of claim 8 , further comprising: re-assigning a subcarrier that is in the first subcarrier group to the second or third subcarrier group when the subcarrier becomes idle.

11. An apparatus for transmitting data over a communication network, wherein a plurality of data flows are carried by respective subcarriers using orthogonal frequency division multiplexing, the apparatus comprising:

means for classifying each of a plurality of data flows as having a respective data flow type;

means for assigning each data flow to one of a plurality of subcarrier groups, based on the data flow's type, wherein each subcarrier group comprises a respective plurality of subcarriers;

means for transmitting first data flows assigned to a first subcarrier group exclusively on respective subcarriers in the first subcarrier group; and

means for transmitting second data flows assigned to a second subcarrier group together on all of the subcarriers in the second subcarrier group;

wherein flow-subcarrier mapping (FSM) with said transmitting (means) includes following constraints:

a

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∑

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≤

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≤

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j

≤

M

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λ

<

M

*

R

;

where R denotes data rate, M denotes optical OFDM subcarriers, N denotes traffic flows, λ is related to traffic intensity, i,j denoting i th data flow mapped to j th subcarrier and Pi,j denoting percentage of i th data flow's traffic that is assigned to j th subcarrier.

12. The apparatus of claim 11 , wherein: the communication network comprises an optical network.

13. The apparatus of claim 11 , wherein the means for classifying each of a plurality of data flows as having a respective data flow type further comprises:

means for classifying each data flow based at least in part on whether or not the data flow has a predictable data rate.

14. The apparatus of claim 13 , wherein the means for classifying each of a plurality of data flows as having a respective data flow type further comprises:

means for classifying each data flow based at least in part on whether or not the data flow needs protection.

15. The apparatus of claim 14 , wherein the means for classifying each of a plurality of data flows as having a respective data flow type further comprises:

means for classifying each data flow as having a data flow type selected from: a first data flow type that does not have a predictable data rate and needs protection, a second data flow type that has a predictable data rate and needs protection, a third data flow type that has a predictable data rate and does not need protection, and a fourth data flow type that does not have a predictable data rate and does not need protection.

16. The apparatus of claim 15 , wherein the means for assigning each data flow to one of a plurality of subcarrier groups further comprises:

means for assigning data flows of the first data flow type to the first subcarrier group;

means for assigning data flows of the second and third data flow types to the second subcarrier group; and

means for assigning data flows of the fourth data flow type to a third subcarrier group.

17. The apparatus of claim 16 , further comprising:

means for transmitting third data flows assigned to the third subcarrier together on all of the subcarriers in the third subcarrier group.

18. The apparatus of claim 17 , further comprising:

means for re-assigning a subcarrier that is not in the first subcarrier group to the first subcarrier group when the subcarrier becomes idle.

19. The apparatus of claim 17 , further comprising:

means for re-assigning a subcarrier that is in the first subcarrier group to the second or third subcarrier group when the subcarrier becomes idle.