REDUCING THE IMPACT OF SUBCARRIER QUALITY EVALUATION

• US 20130251053A1
• Filed: 07/31/2012
• Published: 09/26/2013
• Est. Priority Date: 03/23/2012
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Hui, Jonathan W., Vasseur, Jean-Philippe, Hong, Wei
• Granted Patent: US 8,923,422 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04B 2203/5416 by adding signals to the wave form of the power source
• CPC Class Codes: H04B 3/54 Systems for transmission via power distribution lines
• CPC Class Codes: H04J 11/00 Orthogonal multiplex systems, e.g. using WALSH codesH04J13/00 takes precedence
• CPC Class Codes: H04L 27/0006 Assessment of spectral gaps suitable for allocating digitally modulated signals, e.g. for carrier allocation in cognitive radio for spectrum sharing between different networks H04W16/14
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/003 Arrangements for allocating sub-channels of the transmission path
• CPC Class Codes: H04L 5/0032 Distributed allocation, i.e. involving a plurality of allocating devices, each making partial allocation
• CPC Class Codes: H04L 5/0033 each allocating device acting autonomously, i.e. without negotiation with other allocating devices
• CPC Class Codes: H04L 5/0037 Inter-user or inter-terminal allocation
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/0064 Rate requirement of the data, e.g. scalable bandwidth, data priority
• CPC Class Codes: H04L 5/0094 Indication of how sub-channels of the path are allocated
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

In one embodiment, a device may select, based on an optimal tone map, a particular subcarrier for use when transmitting a data frame, the data frame to serve as a tone map request (TMREQ). The device may then populate one or more unused quality subcarriers of the TMREQ data frame other than the particular subcarrier with a well-known bit sequence, and transmits the TMREQ data frame to a receiving device to cause the receiving device to evaluate transmission quality of the one or more unused quality subcarriers based on the well-known bit sequence.

Claims

1. A method, comprising:

selecting, based on an optimal tone map, a particular subcarrier for use when transmitting a data frame, the data frame to serve as a tone map request (TMREQ);

populating one or more unused quality subcarriers of the TMREQ data frame other than the particular subcarrier with a well-known bit sequence; and

transmitting the TMREQ data frame to a receiving device to cause the receiving device to evaluate transmission quality of the one or more unused quality subcarriers based on the well-known bit sequence.

2. The method as in claim 1, further comprising:

receiving a tone map reply (TMREP) from the receiving device on the particular subcarrier.

3. The method as in claim 1, further comprising:

augmenting a header of the TMREQ data frame with a subcarrier description field.

4. The method as in claim 3, wherein the subcarrier description field is augmented by a two-bit field for each subcarrier to indicate the use of the subcarrier in the particular transmission.

5. The method as in claim 4, wherein the two-bit field is used to describe a condition selected from the group consisting of:

inactive subcarrier for subcarriers not transmitted;

data subcarrier for the particular subcarrier transmitting the data frame; and

quality subcarrier for the one or more unused quality subcarriers.

6. The method as in claim 1, wherein the well-known bit pattern is an erasure code.

7. The method as in claim 1, further comprising:

altering a code-rate of the data frame to adjust an amount of redundant information included in the well-known bit sequence.

8. The method as in claim 1, further comprising:

receiving a tone map reply (TMREP) from the receiving device; and

updating a TMREQ age table for each subcarrier of the one or more unused quality subcarriers.

9. The method as in claim 8, comprising:

aging each TMREQ age table; and

determining whether a TMREQ age table for a particular subcarrier has expired based on comparison to a maximum age.

10. The method as in claim 9, further comprising:

dynamically adjusting the maximum age of a particular TMREQ age table for a particular subcarrier based on a condition selected from the group consisting of;

observed properties of the particular subcarrier and interference;

application requirements on the responsiveness of reacting to changes in subcarrier quality; and

feedback.

11. The method as in claim 9, comprising:

transmitting a TMREQ for the particular subcarrier in response to the TMREQ age table having expired for the particular subcarrier.

12. A method, comprising:

receiving, from a source device, a data frame on a particular subcarrier;

determining if the data frame serves a tone map request (TMREQ);

evaluating transmission quality of one or more unused quality subcarriers based on the well-known bit sequence if the data frame is a TMREQ; and

transmitting a tone map reply (TMREP) to the source device in response to the TMREQ.

13. An apparatus, comprising:

one or more network interfaces adapted to communicate in a computer network;

a processor coupled to the network interfaces and adapted to execute one or more processes; and

a memory configured to store a process executable by the processor, the process when executed operable to;

select, based on an optimal tone map, a particular subcarrier for use when transmitting a data frame, the data frame to serve as a tone map request (TMREQ);

populate one or more unused quality subcarriers of the TMREQ data frame other than the particular subcarrier with a well-known bit sequence; and

transmit the TMREQ data frame to a receiving device to cause the receiving device to evaluate transmission quality of the one or more unused quality subcarriers based on the well-known bit sequence.

14. The apparatus as in claim 13, wherein the process when executed is further operable to:

receive a tone map reply (TMREP) from the receiving device on the particular subcarrier.

15. The apparatus as in claim 13, wherein the process when executed is further operable to:

augment a header of the TMREQ data frame with a subcarrier description field.

16. The apparatus as in claim 15, wherein the subcarrier description field is augmented by a two-bit field for each subcarrier to indicate the use of the subcarrier in the particular transmission.

17. The apparatus as in claim 13, wherein the process when executed is further operable to:

alter a code-rate of the data frame to adjust an amount of redundant information included in the well-known bit sequence.

18. The apparatus as in claim 13, wherein the process when executed is further operable to:

receive a tone map reply (TMREP) from the receiving device; and

update a TMREQ age table for each subcarrier of the one or more unused quality subcarriers.

19. The apparatus as in claim 18, wherein the process when executed is further operable to:

age each TMREQ age table;

determine whether a TMREQ age table for a particular subcarrier has expired based on comparison to a maximum age; and

transmit a TMREQ for the particular subcarrier in response to the TMREQ age table having expired for the particular subcarrier.

20. The apparatus as in claim 18, wherein the process when executed is further operable to:

dynamically adjust the maximum age of a particular TMREQ age table for a particular subcarrier.

21. An apparatus, comprising:

one or more network interfaces adapted to communicate in a computer network;

a processor coupled to the network interfaces and adapted to execute one or more processes; and

a memory configured to store a process executable by the processor, the process when executed operable to;

receive, from a source device, a data frame on a particular subcarrier;

determine if the data frame serves a tone map request (TMREQ);

evaluate transmission quality of one or more unused quality subcarriers based on the well-known bit sequence if the data frame is a TMREQ; and

transmit a tone map reply (TMREP) to the source device in response to the TMREQ.