Pilot symbol transmission in wireless communication systems

• US 9,088,384 B2
• Filed: 08/28/2006
• Issued: 07/21/2015
• Est. Priority Date: 10/27/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Khandekar, Aamod, Agrawal, Avneesh, Gore, Dhananjay Ashok
• Primary Examiner(s): Chang, Kent
• Assistant Examiner(s): WOO, KUO-KONG
• Application Number:
  US11/511,735
• Publication Number:
  US 20070098050A1
• Time in Patent Office: 3,249 Days
• Field of Search: 370/335, 370/329, 370/491, 370/500, 370/208, 370/294, 370/342, 370/203, 370/343, 370/319, 370/209, 375/260, 375/295, 375/299, 375/210, 375/267, 375/347
• US Class Current: 1/1
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04J 13/102 Combining codes
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 25/03866 using scrambling
• CPC Class Codes: H04L 5/0026 Division using four or more dimensions
• CPC Class Codes: H04L 5/0051 of dedicated pilots, i.e. pilots destined for a single user or terminal

Abstract

Pilot symbols transmitted from different sectors of a same base station are multiplied with a same cell specific scrambling code and a first code having low cross correlation and second codes having low cross correlation. The second code is constant over the length of the first code, but may vary for repetitions of the first code.

Claims

1. A wireless communication apparatus, comprising:

at least one processor configured to multiply first pilot symbols for a first antenna group of a base station utilizing a first code sequence of a first group of code sequences, having a low cross-correlation with each other, to further multiply the first pilot symbols utilizing a second code sequence of a second group of code sequences, having a low cross-correlation with each other, to map the first pilot symbols to a set of subcarriers determined based on a predetermined pattern, and to send the first pilot symbols from the first antenna group of the base station.

2. The wireless communication apparatus of claim 1, wherein the at least one processor is configured to multiply the first pilot symbols with a scrambling sequence common to all antenna groups of the base station.

3. The wireless communication apparatus of claim 1, wherein the at least one processor is configured to multiply second pilot symbols for a second antenna group of the base station utilizing another first code sequence of the first group of code sequences, to further multiply the second pilot symbols utilizing another second code sequence of the second group of code sequences, and to send the second pilot symbols from the second antenna group.

4. The wireless communication apparatus of claim 1, wherein the predetermined pattern is a same pattern for the first antenna group and at least one other antenna group of the base station.

5. The wireless communication apparatus of claim 1, wherein the at least one processor is configured to vary the predetermined pattern over time.

6. The wireless communication apparatus of claim 1, wherein the first group of code sequences comprises Walsh codes.

7. The wireless communication apparatus of claim 1, wherein the first group of code sequences comprises orthogonal codes.

8. The wireless communication apparatus of claim 1, wherein the second group of code sequences comprises pseudo-random number (PN) sequences.

9. The wireless communication apparatus of claim 1, wherein the second group of code sequences comprises exponential codes.

10. A method of transmitting pilot symbols comprising:

multiplying first pilot symbols for a first antenna group of a base station utilizing a first code sequence of a first group of code sequences, having a low cross-correlation with each other, and further multiplying the first pilot symbols utilizing a second code sequence of a second group of code sequences, having a low cross-correlation with each other;

mapping the first pilot symbols to a set of subcarriers determined based on a predetermined pattern; and

transmitting the first pilot symbols from the first antenna group.

11. The method of claim 10, further comprising:

multiplying the first pilot symbols by a scrambling sequence common to all antenna groups of the base station.

12. The method of claim 10, wherein the predetermined pattern is a same pattern for the first antenna group and at least one other antenna group of the base station.

13. The method of claim 10, further comprising varying the predetermined pattern over time.

14. The method of claim 10, wherein the first group of code sequences comprises Walsh codes.

15. The method of claim 10, wherein the first group of code sequences comprises orthogonal codes.

16. The method of claim 10, wherein the second group of code sequences comprises pseudo-random number (PN) sequences.

17. The method of claim 10, wherein the second group of code sequences comprises exponential codes.

25. The method of claim 10, further comprising:

multiplying second pilot symbols for a second antenna group of the base station utilizing another first code sequence of the first group of code sequences and further multiplying the second pilot symbols utilizing another second code sequence of the second group of code sequences; and

transmitting the second pilot symbols from the second antenna group.

26. The method of claim 10, wherein the second code sequence is longer than the first code sequence.

27. The method of claim 10, wherein the second code sequence has a constant value over the length of the first code sequence.

28. The method of claim 10, wherein the first code sequence and the second code sequence are applied across a plurality of subcarriers used for pilot transmission.

29. The method of claim 28, wherein the first code sequence is repeated multiple times across the plurality of subcarriers used for pilot transmission.

18. A wireless communication apparatus comprising:

means for multiplying first pilot symbols for a first antenna group of a base station utilizing a first code sequence of a first group of code sequences, having a low cross-correlation with each other, and for further multiplying the first pilot symbols utilizing a second code sequence of a second group of code sequences, having a low cross-correlation with each other;

means for mapping the first pilot symbols to a set of subcarriers determined based on a predetermined pattern; and

a first transmitter configured to transmit the first pilot symbols from the first antenna group.

19. The apparatus of claim 18, further comprising means for varying the predetermined pattern over time.

20. The apparatus of claim 18, wherein the first group of code sequences comprises Walsh codes.

21. The apparatus of claim 18, wherein the first group of code sequences comprises orthogonal codes.

22. The apparatus of claim 18, wherein the second group of code sequences comprises pseudo-random number (PN) sequences.

23. The apparatus of claim 18, wherein the second group of code sequences comprises exponential codes.

24. An article of manufacture, comprising a non-transitory machine-readable medium having instructions therein that, when read by a machine, configure the machine to:

multiply first pilot symbols for a first antenna group of a base station utilizing a first code sequence of a first group of code sequences, having a low cross-correlation with each other,

further multiply the first pilot symbols utilizing a second code sequence of a second group of code sequences, having a low cross-correlation with each other;

map the first pilot symbols to a set of subcarriers determined based on a predetermined pattern; and

send the first pilot symbols from the first antenna group.