METHOD AND APPARATUS FOR CHANNEL FEEDBACK

• US 20070281624A1
• Filed: 06/25/2007
• Published: 12/06/2007
• Est. Priority Date: 11/04/2004
• Status: Abandoned Application

• Current Assignee: Motorola Mobility, Inc. (Lenovo Group Ltd.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Zhuang, Xiangyang, Vook, Frederick, Sartori, Philippe, Baum, Kevin, Thomas, Timothy
• Application Number:
  US11/767,590
• Publication Number:
  US 20070281624A1
• Time in Patent Office: Days
• US Class Current: 455/67.110
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 5/0044 allocation of payload

Abstract

A method for communicating channel estimates on a plurality of subcarriers between a transmitting device and a receiving device. The transmitting device determines a channel estimates on a plurality of subcarriers and then encodes the channel estimates into at least one encoded channel waveform. Then the transmitting device transmits the at least one encoded channel waveform to the receiving device.

Claims

1. A method for a target communication unit to communicate to a source communication unit, knowledge of a channel comprising a plurality of subcarriers, the method comprising the steps of:

determining a plurality of channel estimates for a plurality of subcarriers received from the source communication unit;

producing a channel waveform comprising the plurality of channel estimates; and

communicating knowledge of the channel by transmitting the channel waveform to the source communication unit.

2. The method of claim 1 wherein the channel waveform comprises a combination of the plurality of channel estimates.

5. The method of claim 1 wherein the step of determining a plurality of channel estimates comprises the step of determining a plurality of channel estimates for each of the plurality of subcarriers based on a plurality of transmissions received from the source communication unit.

6. The method of claim 1 wherein the step of determining a plurality of channel estimates for the plurality of subcarriers comprises determining channel estimates for a first plurality of subcarriers corresponding to a first transmission of the source communication unit and determining channel estimates for a second plurality of subcarriers corresponding to a second transmission of the source communication unit.

7. The method of claim 1 wherein the plurality of subcarriers are transmitted by the source communication unit from a plurality of antennas.

8. The method of claim 1 wherein the channel waveform comprises substantially un-quantized channel estimates.

10. The method of claim 1 wherein the channel waveform comprising the plurality of channel estimates comprises channel estimates modulated by a known sequence.

11. The method of claim 1 wherein the step of producing a channel waveform comprises at least one of:

the step of processing the channel estimates so that the channel waveform fits within a dynamic range of a transmitter of the target communication unit;

or

the step of processing the channel waveform so that the channel waveform fits within a dynamic range of a transmitter of the target communication unit.

13. The method of claim 1 wherein the step of producing a channel waveform comprising the plurality of channel estimates comprises producing the channel waveform based on comprising reciprocals of the plurality of channel estimates.

14. The method of claim 1 wherein the step of producing the channel waveform comprises the step of producing the channel waveform from at least one of:

mapping the channel estimates to a predetermined set of subcarriers;

multiplying the channel estimates by a predetermined sequence;

interleaving the channel estimates;

interleaving a combination of the plurality of channel estimates;

or

encoding the channel estimates with a phase shift sequence.

16. The method of claim 1 wherein the channel waveform comprises an orthogonally encoded combination of channel estimates.

17. The method of claim 1 wherein the step of determining the plurality of channel estimates for the plurality of subcarriers comprises the step of determining a plurality of time-domain channel responses for the plurality of subcarriers.

3. (canceled)

4. (canceled)

9. (canceled)

12. (canceled)

15. (canceled)

18. (canceled)

19. A method for obtaining channel estimates, comprising:

receiving a signal comprising a channel waveform, the channel waveform comprising a plurality of channel estimates, wherein the plurality of channel estimates comprise at least one channel estimate for each of a plurality of subcarriers;

estimating a receive channel for the received signal; and

recovering estimates of the plurality of channel estimates based on the received signal and the estimated receive channel.

20. The method of claim 19 further comprising the step of:

receiving a pilot signal; and

wherein the step of estimating the receive channel comprises the step of estimating the receive channel based on the received pilot signal.

21. The method of claim 19 wherein the step of recovering estimates of the plurality of channel estimates comprises recovering a complex channel gain for each of the plurality of channel estimates.

22. The method of claim 19 wherein the step of receiving the signal comprises the step of receiving the signal from the target communication unit, and wherein the channel estimates for each of the plurality of subcarriers are determined by the target communication unit from a downlink signal received by the target communication unit.

23. The method of claim 22 further comprising the step of:

transmitting a plurality of downlink subcarriers, wherein each downlink subcarrier comprises training data; and

wherein the channel waveform comprises a plurality of channel estimates that are based on the training data.

24. The method of claim 19 wherein the channel waveform comprises an orthogonally encoded combination of channel estimates.

25. The method of claim 19 wherein the steps of receiving, estimating, and recovering are performed by a relay/repeater unit.

26. An apparatus for recovering channel estimates, the apparatus comprising:

transmitter circuitry, for receiving a signal comprising a channel waveform, the channel waveform having a plurality of channel estimates, wherein the plurality of channel estimates comprise at least one channel estimate for each of a plurality of subcarriers;

estimation circuitry, for estimating a receive channel for the received signal; and

channel waveform recovery circuitry, for recovering estimates of the plurality of channel estimates based on the received signal and the estimated receive channel.