Channel adaptation synchronized to periodically varying channel

• US 20050190785A1
• Filed: 02/26/2004
• Published: 09/01/2005
• Est. Priority Date: 02/26/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Atheros Communications Incorporated (Qualcomm, Inc.)
• Inventors: Afkhamie, Hassan Kaywan, Yonge, Lawrence W. III, Earnshaw, William E., Kostoff, Stanley J. II, Katar, Srinivas, Blanchard, Bart W., Mashburn, Harper Brent
• Granted Patent: US 7,715,425 B2
• Time in Patent Office: Days
• US Class Current: 370/465
• CPC Class Codes: H04B 2203/5495 having measurements and testing channel
• CPC Class Codes: H04B 3/542 the information being in digital form
• CPC Class Codes: H04L 5/0044 allocation of payload

Abstract

A method of operating in a network (e.g., a power line communication network) in which a plurality of stations communicate over a shared medium (e.g., an AC power line) having a periodically varying channel. The method includes determining a plurality of channel adaptations (e.g., tone maps) for communication between a pair of stations, and assigning a different one of the plurality of channel adaptations to each of a plurality of phase regions of the periodically varying channel.

Claims

1. A method of operating in a network in which a plurality of stations communicate over a shared medium having a periodically varying channel, comprising

determining a plurality of channel adaptations for communication between a pair of stations;

assigning a different one of the plurality of channel adaptations to each of a plurality of phase regions of the periodically varying channel.

2. The method of claim 1 wherein the channel adaptations for a particular phase region are adapted to the channel in that phase region.

3. The method of claim 2 wherein the network is a power line communication network, the shared medium is an AC power line, and the channel characteristics vary with the phase of the AC line cycle.

7. The method of claim 1, 4 or 6 where channel adaptation is substantially unique between any pair of transmitter and receiver.

9. The method of claims 1 or 4 wherein each station has a channel adaptation facility that interacts with the channel facility at other stations.

11. The method of claim 9 wherein the channel adaptation facility comprises a tone map generator for generating a tone map.

21. The method of claim 11 wherein associated with each tone map is an indication of the tolerance of that tone map for use outside its boundaries.

4. A method of operating in a network in which a plurality of stations communicate over a shared medium having a periodically varying channel, comprising synchronizing channel adaptation to the periodically varying channel.

5. The method of claim 4 wherein the network is a power line communication network, the shared medium is an AC power line, and the channel characteristics vary with the phase of the AC line cycle.

28. The method of claim 4 wherein time stamps are transmitted between stations to aid synchronization of channel adaptation.

6. A method of operating in a power line communication network in which a plurality of stations communicate over an AC power line in which the channel characteristics vary with the phase of the AC line cycle, comprising synchronizing channel adaptation to the phase of the AC line cycle.

8. The method of claim 6 wherein each station has a channel adaptation facility that interacts with the channel facility at other stations.

10. The method of claim 8 wherein the channel adaptation facility comprises a tone map generator for generating a tone map.

12. The method of claim 10 wherein the channel adaptation facility comprises an indication of the start of the AC line cycle.

13. The method of claim 10 wherein the stations exchange tone maps.

14. The method of claim 10 wherein the tone map generator has the capability to generate multiple tone maps, with different tone maps being assigned to different phases regions of the AC line cycle.

15. The method of claim 14 wherein different tone maps are assigned to different regions of each half cycle of the AC line cycle, with each half cycle of the AC line cycle being treated as equivalent to the other half cycle for the purpose of channel adaptation.

16. The method of claim 14 wherein the AC line cycle is divided into a plurality of substantially equal size phase regions, to which a different tone map may be assigned.

17. The method of claim 16 wherein some of the substantially equal size phase regions are assigned the same tone map.

18. The method of claim 15 wherein the AC line cycle is divided into a plurality of substantially equal size phase regions, to which a different tone map may be assigned.

19. The method of claim 18 wherein some of the substantially equal size phase regions are assigned the same tone map.

20. The method of claim 10 wherein associated with each tone map is an indication of the tolerance of that tone map for use outside its boundaries.

22. The method of claim 12 wherein the indication of the start of an AC line cycle comprises recognition of an AC line cycle zero crossing.

23. The method of claim 12 wherein the indication of the start of an AC line cycle comprises recognition of an AC line cycle zero crossing followed by a rising signal.

24. The method of claim 12 wherein the indication of the start of an AC line cycle comprises recognition of an AC line cycle zero crossing followed by a falling signal.

25. The method of claim 12 wherein the indication of the start of an AC line cycle comprises recognition of a repeating feature in the AC line signal.

26. The method of claim 25 wherein the repeating feature in the AC line signal comprises one or more of the following:

a zero crossing, a peak in AC power amplitude, a peak or a minimum in noise amplitude.

27. The method of claim 6 wherein time stamps are transmitted between stations to aid synchronization of channel adaptation to the AC line cycle.

29. The method of claim 6 wherein the phase of the AC line cycle at a receiving station is offset from the AC line cycle at a transmitting station, and information relating to the phase offset is provided to the transmitting station so that the channel adaptation used by the transmitting station is synchronized to the AC line cycle at the receiving station.

30. The method of claim 29 wherein the information relating to the phase offset comprises a zero crossing offset between the receiving and transmitting stations.

31. The method of claim 30 wherein the receiving station determines the zero crossing offset, and transmits it to the transmitting station.

32. The method of claim 31 wherein the transmitting station determines the zero crossing offset.

33. The method of claim 22 wherein one station in the network tracks the AC line cycle zero crossing and transmits information on the time of the zero crossing to a plurality of stations on the network, and wherein the plurality of stations use the time of the zero crossing at the one station as their own local AC line cycle zero crossing.

34. The method of claim 22 wherein the AC line cycle zero crossing is derived using virtual tracking, wherein a station uses its local clock along with knowledge of the AC line cycle frequency to track a virtual zero crossing.

35. The method of claim 14 wherein the number of tone map regions, boundaries of each region, and the tone map for each region are determined based on periodically varying channel attenuation characteristics.

36. The method of claim 14 wherein the number of tone map regions, boundaries of each region, and the tone map for each region are determined based on periodically varying local noise characteristics.

37. The method of claim 14 wherein data is transmitted in packets that include at least one header and one payload, and wherein the tone map boundaries and length of the packets are configured so that the payload of most packets is transmitted within one phase region so that the payload does not cross a boundary between tone maps.

38. The method of claim 14 wherein data is transmitted in packets that include at least one header and one payload, and wherein the tone map boundaries and length of the packets are configured so that the payload of at least some packets is transmitted in two adjoining phase regions, so that a first portion of the payload is transmitted using one tone map and a second portion of the payload is transmitted using a second tone map.