Method and Apparatus for use of Silent Symbols in a Communications Network

• US 20110182199A1
• Filed: 01/25/2011
• Published: 07/28/2011
• Est. Priority Date: 01/26/2010
• Status: Active Grant

• Current Assignee: Entropic Communications, LLC (SoftBank Group Corp.)
• Original Assignee: Entropic Communications Incorporated (Maxlinear Incorporated)
• Inventors: BARR, David
• Granted Patent: US 8,593,983 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

Systems and methods for characterizing a communication channel including transmitting silent symbols during periods of a packet.

Claims

1. A method for characterize a communication channel on a communication network, comprising:

a) receiving within a network node at least one silent symbol transmitted together with a packet; and

b) determining within the network node the amount of energy received by the network node during the silent symbol.

2. The method of claim 1, further including characterizing the amount of received energy in order to determine a further course of action.

3. The method of claim 1, wherein the packet transmitted with the silent symbol includes a preamble and the silent symbol is transmitted before the preamble.

4. The method of claim 1, wherein the silent symbol is transmitted within the packet.

5. The method of claim 4, wherein packet includes data symbols and the silent symbol is transmitted for a duration that is shorter than the duration of one data symbol transmitted in the packet.

6. The method of claim 1, wherein characterizing the amount of received energy includes comparing the amount of energy received during a first silent symbol with the amount of energy received during subsequent silent symbols.

7. The method of claim 1, wherein characterizing the amount of received energy includes comparing the amount of energy received during a first silent symbol with at least one of the following:

a) channel equalization (CE) Symbol(s) in the preamble;

b) data payloads;

c) error vector magnitude (EVM) Probes;

or

d) silent probes.

8. The method of claim 1, wherein the silent symbol occurs after the end of the packet.

9. The method of claim 1, wherein the packet includes a preamble and a payload and the silent symbol is transmitted between the preamble and the payload.

10. The method of claim 1, wherein no power is transmitted by any node in the network during the silent symbol.

11. The method of claim 1, wherein the further course of action includes employing a targeted mitigation technique to mitigate noise detected during the silent symbol.

12. The method of claim 1, further including determining the contribution of a previous transmitter during a decay period.

13. The method of claim 12, further including subtracting the contribution of the previous transmitter during the decay period from the characterized received amount of energy.

14. The method of claim 1, further including determining the amount of energy contributed during a ramp up of a next node to transmit.

15. The method of claim 14, further including subtracting the energy contributed during the ramp up of the previous transmitter from the characterized received amount of energy.

16. A method for characterizing a communication channel on a MoCA communication network, comprising:

e) receiving within a network node of a MoCA network, instructions from a network coordinator to transmit at least one silent symbol; and

f) transmitting from the network node at least one silent symbol.

17. The method of claim 16, wherein the duration of the silent symbol is shorter than the duration of a data symbol transmitted in the same packet.

18. The method of claim 16, wherein the duration of the silent symbol is greater than the duration of a data symbol transmitted in the same packet.

19. The method of claim 16, wherein transmitting the silent symbol includes transmitting a packet that includes a preamble and in which the silent symbol is transmitted before the preamble.

20. The method of claim 19, wherein the silent symbol is concurrent with an IFG (inter-frame gap) and the silent symbol includes a period of time during which receiving nodes can measure the amount of energy present.

21. The method of claim 16, wherein the silent symbol is transmitted after the end of the payload.

22. The method of claim 16, wherein the silent symbol is transmitted between the preamble and the payload.

23. The method of claim 16, wherein no power is transmitted by any node in the network during the silent symbol.

24. A method of characterizing a communication channel of a network including:

a) in a node of the network, zeroing at least one of the subcarriers in the payload symbols; and

b) transmitting from a transmitting node the at least one subcarrier with the zeroed payload symbols.

25. The method of claim 24, wherein the transmitting node zeros particular subcarriers in a predetermined sequence.

26. The method of claim 25, wherein the transmitting node zeros a few different subcarriers for each consecutive transmitted symbol.

27. The method of claim 26, wherein the sequence of zeroed subcarriers can be constructed to monitor all of the subcarriers used for communication.

28. The method of claim 26, wherein the sequence of zeroed subcarriers can be designed to concentrate on monitoring portions of a communication spectrum for the network.

29. The method of claim 28, wherein the sequence is repeated indefinitely over time.

30. The method of claim 28, wherein the sequence is modified according to conditions observed on the communications channel.

31. The method of claim 30, wherein new or modified sequences can be distributed among network nodes.

32. A method of characterizing a communication channel of a network including:

a) receiving in a node of the network at least one silent subcarrier transmitted by another node of the network, the payload symbols of the silent subcarrier having been zeroed; and

b) in the receiving node of the network, measuring the energy received in frequency bins of the at least one silent subcarrier.

33. A method of characterizing a communication channel of a network including:

a) transmitting instructions from a network coordinator to a network node, the instructions instructing the network node to transmit a silent symbol; and

b) receiving from the network node an indication of the amount of energy present on a subcarrier on which the silent symbol was transmitted.

34. The method of claim 33, further including determining from the amount of energy whether there is interference present on the subcarrier.

35. The method of claim 34, further including instructing the network node not to transmit information over the subcarrier if there is more than a predetermined amount of interference on the subcarrier.

36. A method of characterizing a communication channel of a network including:

a) transmitting instructions from a network coordinator to a network node, the instructions instructing the network node to transmit a silent subcarrier; and

b) receiving from the network node an indication of the amount of energy present on a subcarrier on which the silent subcarrier was transmitted.

37. The method of claim 36, further including determining from the amount of energy whether there is interference present on the subcarrier.

38. The method of claim 37, further including instructing the network node not to transmit information over the subcarrier if there is more than a predetermined amount of interference on the subcarrier.