Method and apparatus for multi-path elimination in a wireless communication system

• US 20030048753A1
• Filed: 08/30/2001
• Published: 03/13/2003
• Est. Priority Date: 08/30/2001
• Status: Abandoned Application

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Jalali, Ahmad
• Application Number:
  US09/943,277
• Publication Number:
  US 20030048753A1
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04B 7/0845 per branch equalization, e.g. by an FIR-filter or RAKE receiver per antenna branch rake receivers as such H04B1/7115
• CPC Class Codes: H04L 2025/03656 Initialisation
• CPC Class Codes: H04L 2025/03808 Transmission of equaliser coefficients
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 5/0051 of dedicated pilots, i.e. pilots destined for a single user or terminal

Abstract

Method and apparatus for pre-coding in a communication system are disclosed. In a communication system, an origination station transmits a non pre-coded pilot signal and a pre-coded data signal. A destination station estimates a metric characterizing a communication channel using the non pre-coded pilot signal. The metric is then used to pre-code the data signal to be transmitted. The destination station may also use the estimated metric for demodulation of the pre-coded data. However, since the pilot signal is not pre-coded, the metric for the desired multi-path of the pilot channel differs from that of the pre-coded data channel, which may reduce the demodulation performance. To improve the channel estimation for data demodulation, the origination station may additionally transmit a dedicated pilot signal that is pre-coded in the same manner as the data signal destined to a specific user.

Claims

1. A method for pre-coding in a communication system, comprising:

determining pre-coder parameters;

pre-coding first data in accordance with said determined pre-coder parameters;

transmitting said pre-coded first data; and

transmitting non pre-coded first reference data.

2. The method as claimed in claim 1 wherein determining a pre-coder parameters comprises:

receiving a reference data; and

determining the pre-coder parameters in accordance with said received reference data and the reference data.

3. The method as claimed in claim 1 wherein determining a pre-coder parameters comprises:

receiving the non pre-coded first reference data;

determining the pre-coder parameters in accordance with said received non pre-coded first reference data and the first reference data; and

transmitting said determined pre-coder parameters.

4. The method as claimed in claim 3 further comprising:

receiving said determined pre-coder parameters; and

providing said determined pre-coder parameters to the pre-coder.

5. The method as claimed in claim 1 wherein pre-coding first data in accordance with said determined parameters comprises:

pre-coding a payload data; and

pre-coding a dedicated pilot data.

6. The method of claim 1 wherein said transmitting a non pre-coded reference data comprises:

transmitting a continuous non pre-coded reference data.

7. The method of claim 1 wherein said transmitting a non pre-coded reference data comprises:

transmitting a discontinuous non pre-coded reference data.

8. The method of claim 1 wherein said transmitting a non pre-coded reference data comprises:

transmitting a pilot data.

9. The method as claimed in claim 1, further comprising:

receiving the non pre-coded first reference data at least two antennae;

equalizing each of said received non pre-coded first reference data by an equalizer and provide equalized non pre-coded first reference data;

determining the pre-coder parameters by adjusting characteristics of the at least two equalizers in accordance with the received non pre-coded first reference data and the first reference data; and

transmitting said determined pre-coder parameters.

10. The method as claimed in claim 9 wherein said determining the pre-coder parameters by adjusting characteristics of the at least two equalizers in accordance with the received non pre-coded first reference data and the first reference data comprises:

optimizing a quality metric of a composite data comprising the equalized non pre-coded first reference data.

11. A method for demodulating pre-coded data, comprising:

receiving a reference data and a pre-coded data; and

determining demodulator parameters in accordance with the said received reference data and the reference data; and

demodulating the pre-coded data in accordance with said determined demodulator parameters.

12. The method as claimed in claim 11 wherein the reference data comprise a non pre-coded pilot signal.

13. The method as claimed in claim 11 wherein the reference data comprise a pre-coded pilot signal.

14. The method as claimed in claim 11 wherein the reference data are continuous reference data.

15. The method as claimed in claim 11 wherein the reference data are discontinuous reference data.

16. An apparatus for pre-coding in a communication system, comprising:

a pre-coder configured to pre-code data in accordance with pre-coder parameters; and

a first transmitter communicatively coupled to said pre-coder configured to;

transmit the pre-coded data; and

transmit a non pre-coded first reference data.

17. The apparatus as claimed in claim 16, further comprising:

a first receiver communicatively coupled to said pre-coder configured to receive a reference data;

a first processor communicatively coupled to said first receiver; and

a storage medium communicatively coupled to said first processor and containing a set of instructions executable by the processor to;

determine the pre-coder parameters in accordance with said received reference data and the reference data.

18. The apparatus as claimed in claim 16, further comprising:

a second receiver configured to receive the non pre-coded first reference data;

a second processor communicatively coupled to said second receiver;

a storage medium communicatively coupled to said first processor and containing a set of instructions executable by the processor to;

determine the pre-coder parameters in accordance with said received non pre-coded first reference data and the non pre-coded first reference data; and

a second transmitter communicatively coupled to said second processor configured to transmitting said determined pre-coder parameters.

19. The apparatus as claimed in claim 18, wherein said first receiver is further configured to:

receive said determined pre-coder parameters; and

provide said received pre-coder parameters to said pre-coder.

20. The apparatus as claimed in claim 16 wherein said pre-coder is further configured to pre-code a second reference data in accordance with the determined parameters;

and

wherein said first transmitter is further configured to transmit the pre-coded second reference data.

21. The apparatus as claimed in claim 16 wherein said first transmitter is further configured to transmit the non pre-coded first reference data continuously.

22. The apparatus as claimed in claim 16 wherein said first transmitter is further configured to transmit the non pre-coded first reference data discontinuously.

23. The apparatus of claim 16 wherein said non pre-coded first reference data comprise a pilot data.

24. The apparatus as claimed in claim 20 wherein said first transmitter is further configured to transmit the pre-coded second reference data continuously.

25. The apparatus as claimed in claim 20 wherein said first transmitter is further configured to transmit the pre-coded second reference data discontinuously.

26. The apparatus of claim 20 wherein said pre-coded second reference data comprise a dedicated pilot data.

27. The apparatus as claimed in claim 16, further comprising:

at least two equalizers configured to accept the received non pre-coded first reference data and provide equalized non pre-coded first reference data;

a processor communicatively coupled to said at least two equalizers;

a storage medium communicatively coupled to the processor and containing a set of instructions executable by the processor to determine said pre-coder parameters by adjusting characteristics of the at least two equalizers in accordance with the received non pre-coded first reference data and the first reference data; and

a second transmitter communicatively coupled to said processor configured to transmit the determined pre-coder parameters.

28. The apparatus as claimed in claim 16 wherein said processor determines said pre-coder characteristics by adjusting characteristics of the at least two equalizers in accordance with the non pre-coded first reference data the first reference data by executing a set of instructions to:

optimize a quality metric of a composite data comprising the equalized non pre-coded first reference data.

29. An apparatus for demodulating pre-coded data, comprising:

a first receiver configured to;

receive a reference data and a pre-coded data; and

determine demodulator parameters in accordance with the said received reference data and the reference data; and

a demodulator communicatively coupled to said receiver configured to demodulate the pre-coded data in accordance with said determined demodulator parameters.

30. The apparatus as claimed in claim 29 wherein the reference data comprise a non pre-coded pilot signal.

31. The apparatus as claimed in claim 29 wherein the reference data comprise a pre-coded pilot signal.

32. The apparatus as claimed in claim 29 wherein the reference data are continuous reference data.

33. The apparatus as claimed in claim 29 wherein the reference data are discontinuous reference data.

34. A digital signal processing apparatus for pre-coding in a communication system, comprising:

memory storage unit; and

a digital signal processor communicatively coupled to said memory storage unit, and capable of executing instructions to;

determine pre-coder parameters;

pre-code first data in accordance with the determined pre-coder parameters; and

assist in preparing the pre-coded first data and non pre-coded first reference data for transmission.

35. A digital signal processing apparatus for demodulating pre-coded data in a communication system, comprising:

memory storage unit; and

a digital signal processor communicatively coupled to said memory storage unit, and capable of executing instructions to;

accept a reference data and a pre-coded data;

determine demodulating parameters in accordance with the accepted reference data and the reference data; and

demodulate the pre-coded data in accordance with the determined demodulating parameters.

36. An apparatus for pre-coding in a communication system, comprising:

means for determining a pre-coder parameters;

means for pre-coding first data in accordance with said determined pre-coder parameters;

means for transmitting said pre-coded first data and a non pre-coded first reference data.

37. An apparatus for demodulating pre-coded data, comprising:

means for receiving a reference data and a pre-coded data; and

means for determining demodulator parameters in accordance with the said received reference data and the reference data; and

means for demodulating the pre-coded data in accordance with said determined demodulator parameters.