Pilot structures for ACK and CQI in a wireless communication system

1. An apparatus for wireless communication, comprising:

at least one processor configured to:

select first and second orthogonal sequences from a set of orthogonal sequences generated based on a discrete Fourier transform (DFT) matrix;

select first and second reference signal sequences from a set of reference signal sequences generated based on different cyclic shifts of a base sequence;

assign the first reference signal sequence and the first orthogonal sequence to a first user equipment (UE) for sending pilot;

assign the second reference signal sequence and the second orthogonal sequence to a second UE for sending pilot;

receive a first set of pilot sequences from the first UE on multiple subcarriers in multiple symbol periods, the first set of pilot sequences being generated by the first UE based on the first reference signal sequence and the first orthogonal sequence; and

receive a second set of pilot sequences from the second UE on the multiple subcarriers in the multiple symbol periods, the second set of pilot sequences being generated by the second UE based on the second reference signal sequence and the second orthogonal sequence.

2. An apparatus for wireless communication, comprising:

at least one processor configured to:

select first and second orthogonal sequences from a set of orthogonal sequences generated based on a discrete Fourier transform (DFT) matrix;

select first and second reference signal sequences from a set of reference signal sequences generated based on different cyclic shifts of a base sequence;

assign the first reference signal sequence and the first orthogonal sequence to a first user equipment (UE) for sending pilot sequences;

assign the second reference signal sequence and the second orthogonal sequence to a second UE for sending pilot sequences;

assign the first reference signal sequence and the second orthogonal sequence to a third UE for sending pilot sequences; and

assign the second reference signal sequence and the first orthogonal sequence to a fourth UE for sending pilot sequences.

3. An apparatus for wireless communication, comprising:

at least one processor configured to:

select first and second orthogonal sequences from a set of orthogonal sequences generated based on a discrete Fourier transform (DFT) matrix;

select first and second reference signal sequences from a set of reference signal sequences generated based on different cyclic shifts of a base sequence;

assign the first reference signal sequence and the first orthogonal sequence to a first user equipment (UE) for sending pilot sequences;

assign the second reference signal sequence and the second orthogonal sequence to a second UE for sending pilot sequences;

select third and fourth orthogonal sequences from a second set of orthogonal sequences generated based on a Walsh matrix;

assign the third orthogonal sequence to the first UE for sending data;

assign the fourth orthogonal sequence to the second UE for sending data;

receive a first set of data sequences from the first UE on multiple subcarriers in multiple symbol periods, the first set of data sequences being generated by the first UE based on the first reference signal sequence and the third orthogonal sequence; and

receive a second set of data sequences from the second UE on the multiple subcarriers in the multiple symbol periods, the second set of data sequences being generated by the second UE based on the second reference signal sequence and the fourth orthogonal sequence.

4. An apparatus for wireless communication, comprising:

means for selecting first and second orthogonal sequences from a set of orthogonal sequences generated based on a discrete Fourier transform, DFT, matrix,

means for selecting first and second reference signal sequences from a set of reference signal sequences generated based on different cyclic shifts of a base sequence,

means for assigning the first reference signal sequence and the first orthogonal sequence to a first user equipment, UE, for sending pilot sequences, and

means for assigning the second reference signal sequence and the second orthogonal sequence to a second UE for sending pilot sequences.

5. The apparatus of claim 4 , further comprising:

means for receiving a first set of pilot sequences from the first UE on multiple subcarriers in multiple symbol periods, the first set of pilot sequences being generated by the first UE based on the first reference signal sequence and the first orthogonal sequence; and

means for receiving a second set of pilot sequences from the second UE on the multiple subcarriers in the multiple symbol periods, the second set of pilot sequences being generated by the second UE based on the second reference signal sequence and the second orthogonal sequence.

6. The apparatus of claim 4 , further comprising:

means for assigning the first reference signal sequence and the second orthogonal sequence to a third UE for sending pilot sequences; and

means for assigning the second reference signal sequence and the first orthogonal sequence to a fourth UE for sending pilot sequences.

7. The apparatus of claim 4 , further comprising:

means for selecting third and fourth orthogonal sequences from a second set of orthogonal sequences generated based on a Walsh matrix;

means for assigning the third orthogonal sequence to the first UE for sending data sequences; and

means for assigning the fourth orthogonal sequence to the second UE for sending data sequences.

8. The apparatus of claim 7 , further comprising:

means for receiving a first set of data sequences from the first UE on multiple subcarriers in multiple symbol periods, the first set of data sequences being generated by the first UE based on the first reference signal sequence and the third orthogonal sequence; and

means for receiving a second set of data sequences from the second UE on the multiple subcarriers in the multiple symbol periods, the second set of data sequences being generated by the second UE based on the second reference signal sequence and the fourth orthogonal sequence.

9. A non-transitory computer-readable medium, comprising:

code for selecting first and second orthogonal sequences from a set of orthogonal sequences generated based on a discrete Fourier transform (DFT) matrix;

code for selecting first and second reference signal sequences from a set of reference signal sequences generated based on different cyclic shifts of a base sequence;

code for assigning the first reference signal sequence and the first orthogonal sequence to a first user equipment (UE) for sending pilot sequences; and

code for assigning the second reference signal sequence and the second orthogonal sequence to a second UE for sending pilot sequences.

10. The computer-readable medium of claim 9 , further comprising:

code for receiving a first set of pilot sequences from the first UE on multiple subcarriers in multiple symbol periods, the first set of pilot sequences being generated by the first UE based on the first reference signal sequence and the first orthogonal sequence; and

code for receiving a second set of pilot sequences from the second UE on the multiple subcarriers in the multiple symbol periods, the second set of pilot sequences being generated by the second UE based on the second reference signal sequence and the second orthogonal sequence.

11. The computer-readable medium of claim 9 , further comprising:

code for assigning the first reference signal sequence and the second orthogonal sequence to a third UE for sending pilot sequences; and

code for assigning the second reference signal sequence and the first orthogonal sequence to a fourth UE for sending pilot sequences.

12. The computer-readable medium of claim 9 , further comprising:

code for selecting third and fourth orthogonal sequences from a second set of orthogonal sequences generated based on a Walsh matrix;

code for assigning the third orthogonal sequence to the first UE for sending data sequences; and

code for assigning the fourth orthogonal sequence to the second UE for sending data sequences.

13. The computer-readable medium of claim 12 , further comprising:

code for receiving a first set of data sequences from the first UE on multiple subcarriers in multiple symbol periods, the first set of data sequences being generated by the first UE based on the first reference signal sequence and the third orthogonal sequence; and

code for receiving a second set of data sequences from the second UE on the multiple subcarriers in the multiple symbol periods, the second set of data sequences being generated by the second UE based on the second reference signal sequence and the fourth orthogonal sequence.

14. A method for wireless communication, comprising:

receiving multiple pilot sequences on multiple subcarriers in multiple symbol periods, each pilot sequence in a different symbol period;

obtaining an orthogonal sequence from a set of orthogonal sequences generated based on a discrete Fourier transform (DFT) matrix;

despreading the multiple pilot sequences with the orthogonal sequence to obtain a despread pilot sequence; and

deriving a channel estimate based on the despread pilot sequence.

15. The method of claim 14 , wherein the receiving multiple pilot sequences comprises receiving three pilot sequences in three symbol periods of a slot comprising seven symbol periods, and wherein the despreading the multiple pilot sequences comprises despreading the three pilot sequences with the orthogonal sequence of length three to obtain the despread pilot sequence.

16. The method of claim 14 , further comprising:

receiving multiple data sequences on the multiple subcarriers in multiple symbol periods for data, one data sequence in each symbol period for data; and

performing coherent detection for the multiple data sequences with the channel estimate to obtain multiple detected data sequences.

17. The method of claim 16 , further comprising:

despreading the multiple detected data sequences with a second orthogonal sequence to obtain a despread data sequence; and

recovering acknowledgement (ACK) information based on the despread data sequence.

18. An apparatus for wireless communication, comprising:

at least one processor configured to:

receive multiple pilot sequences on multiple subcarriers in multiple symbol periods, each pilot sequence in a different symbol period;

obtain an orthogonal sequence from a set of orthogonal sequences generated based on a discrete Fourier transform (DFT) matrix;

despread the multiple pilot sequences with the orthogonal sequence to obtain a despread pilot sequence; and

derive a channel estimate based on the despread pilot sequence.

19. The apparatus of claim 18 , wherein the receiving multiple pilot sequences comprises receiving three pilot sequences in three symbol periods of a slot comprising seven symbol periods, and wherein the despreading the multiple pilot sequences comprises despreading the three pilot sequences with the orthogonal sequence of length three to obtain the despread pilot sequence.

20. The apparatus of claim 18 , wherein the at least one processor is further configured to:

receive multiple data sequences on the multiple subcarriers in multiple symbol periods for data, one data sequence in each symbol period for data; and

perform coherent detection for the multiple data sequences with the channel estimate to obtain multiple detected data sequences.

21. The apparatus of claim 20 , wherein the at least one processor is further configured to:

despread the multiple detected data sequences with a second orthogonal sequence to obtain a despread data sequence; and

recover acknowledgement (ACK) information based on the despread data sequence.

22. An apparatus for wireless communication, comprising:

means configured to receive multiple pilot sequences on multiple subcarriers in multiple symbol periods, each pilot sequence in a different symbol period,

means for obtaining an orthogonal sequence from a set of orthogonal sequences generated based on a discrete Fourier transform (DFT) matrix,

means to despread the multiple pilot sequences with the orthogonal sequence to obtain a despread pilot sequence, and

means to derive a channel estimate based on the despread pilot sequence.

23. The apparatus of claim 22 , wherein the receiving multiple pilot sequences comprises receiving three pilot sequences in three symbol periods of a slot comprising seven symbol periods, and wherein the despreading the multiple pilot sequences comprises despreading the three pilot sequences with the orthogonal sequence of length three to obtain the despread pilot sequence.

24. The apparatus of claim 22 , further comprising:

means for receiving multiple data sequences on the multiple subcarriers in multiple symbol periods for data, one data sequence in each symbol period for data; and

means for performing coherent detection for the multiple data sequences with the channel estimate to obtain multiple detected data sequences.

25. The apparatus of claim 24 , further comprising:

means for despreading the multiple detected data sequences with a second orthogonal sequence to obtain a despread data sequence; and

means for recovering acknowledgement (ACK) information based on the despread data sequence.

26. A non-transitory computer-readable medium, comprising:

code for receiving multiple pilot sequences on multiple subcarriers in multiple symbol periods, each pilot sequence in a different symbol period;

code for obtaining an orthogonal sequence from a set of orthogonal sequences generated based on a discrete Fourier transform (DFT) matrix;

code for despreading the multiple pilot sequences with the orthogonal sequence to obtain a despread pilot sequence; and

code for deriving a channel estimate based on the despread pilot sequence.

27. The computer-readable medium of claim 26 , wherein the receiving multiple pilot sequences comprises receiving three pilot sequences in three symbol periods of a slot comprising seven symbol periods, and wherein the despreading the multiple pilot sequences comprises despreading the three pilot sequences with the orthogonal sequence of length three to obtain the despread pilot sequence.

28. The computer-readable medium of claim 26 , further comprising:

code for receiving multiple data sequences on the multiple subcarriers in multiple symbol periods for data, one data sequence in each symbol period for data; and

code for performing coherent detection for the multiple data sequences with the channel estimate to obtain multiple detected data sequences.

29. The computer-readable medium of claim 28 , further comprising:

code for despreading the multiple detected data sequences with a second orthogonal sequence to obtain a despread data sequence; and

code for recovering acknowledgement (ACK) information based on the despread data sequence.