Spread-spectrum coding of data bursts
Certain aspects of the present disclosure relate to a method for generating spread-spectrum coded signals for transmission in a wireless communication system, and particularly for generating spread sequences of data with spreading codes that facilitate computationally efficient frequency-domain processing at a receiver.
1. A method for wireless communications, comprising:
receiving a spread data stream generated by spreading sub-blocks of data using a matrix with M orthogonal rows,
combining sub-blocks of the received spread data stream, wherein the combination is based on the matrix with M orthogonal rows to generate M sets of combined spread sub-blocks;
generating, using a plurality of the combined spread sub-blocks of a first size, spread sub-blocks of a second size smaller than the first size; and
processing the spread sub-blocks of the second size to obtain estimates of original non-spread data.
2. The method of claim 1 , wherein:
generating the spread sub-blocks of the second size comprises decimating the plurality of combined spread sub-blocks of the first size; and
processing the spread sub-blocks of the second size comprises equalizing the spread sub-blocks of the second size to obtain the estimates of the original non-spread data.
3. The method of claim 2 , wherein equalizing comprises filtering in a frequency domain and applying an inverse fast Fourier transform (IFFT) on filtered frequency domain data to obtain time domain data estimates.
4. The method of claim 3 , wherein filtering in the frequency domain comprises filtering based on a minimum mean square error (MMSE) technique.
5. The method of claim 1 , wherein the matrix is a Hadamard matrix.
6. The method of claim 5 , wherein the Hadamard matrix has two rows and two columns.
7. The method of claim 5 , wherein the Hadamard matrix has four rows and four columns.
8. An apparatus for wireless communications, comprising:
a receiver configured to receive a spread data stream generated by spreading sub-blocks of data using a matrix with M orthogonal rows;
a combiner configured to combine sub-blocks of the received spread data stream, wherein the combination is based on the matrix with M orthogonal rows to generate M sets of combined spread sub-blocks;
a first circuit configured to generate, using a plurality of the combined spread sub-blocks of a first size, spread sub-blocks of a second size smaller than the first size; and
a second circuit configured to process the spread sub-blocks of the second size to obtain estimates of original non-spread data.
9. The apparatus of claim 8 , wherein:
the first circuit comprises a decimator configured to decimate the plurality of combined spread sub-blocks of the first size; and
the second circuit comprises an equalizer configured to equalize the spread sub-blocks of the second size to obtain the estimates of the original non-spread data.
10. The apparatus of claim 9 , wherein the equalizer comprises a filter configured to filter in a frequency domain and a circuit configured to apply an inverse fast Fourier transform (IFFT) on filtered frequency domain data to obtain time domain data estimates.
11. The apparatus of claim 10 , wherein the filter configured to filter in the frequency domain comprises a circuit configured to filter based on a minimum mean square error (MMSE) technique.
12. The apparatus of claim 8 , wherein the matrix is a Hadamard matrix.
13. The apparatus of claim 12 , wherein the Hadamard matrix has two rows and two columns.
14. The apparatus of claim 12 , wherein the Hadamard matrix has four rows and four columns.
15. An apparatus for wireless communications, comprising:
means for receiving a spread data stream generated by spreading sub-blocks of data using a matrix with M orthogonal rows;
means for combining sub-blocks of the received spread data stream, wherein the combination is based on the matrix with M orthogonal rows to generate M sets of combined spread sub-blocks;
means for generating, using a plurality of the combined spread sub-blocks of a first size, spread sub-blocks of a second size smaller than the first size; and
means for processing the spread sub-blocks of the second size to obtain estimates of original non-spread data.
16. The apparatus of claim 15 , wherein:
the means for generating comprises means for decimating the plurality of combined spread sub-blocks of the first size; and
the means for processing comprises means for equalizing the spread sub-blocks of the second size to obtain the estimates of the original non-spread data.
17. The apparatus of claim 16 , wherein the means for equalizing comprises means for filtering in a frequency domain and means for applying an inverse fast Fourier transform (IFFT) on filtered frequency domain data to obtain time domain data estimates.
18. The apparatus of claim 17 , wherein the means for filtering in the frequency domain comprises means for filtering based on a minimum mean square error (MMSE) technique.
19. The apparatus of claim 15 , wherein the matrix is a Hadamard matrix.
20. The apparatus of claim 19 , wherein the Hadamard matrix has two rows and two columns.
21. The apparatus of claim 19 , wherein the Hadamard matrix has four rows and four columns.
22. A computer-program product for wireless communications, comprising a non-transitory computer-readable medium encoded with instructions executable to:
receive a spread data stream generated by spreading sub-blocks of data using a matrix with M orthogonal rows;
combine sub-blocks of the received spread data stream, wherein the combination is based on the matrix with M orthogonal rows to generate M sets of combined spread sub-blocks;
generate, using a plurality of the combined spread sub-blocks of a first size, spread sub-blocks of a second size smaller than the first size; and
process the spread sub-blocks of the second size to obtain estimates of original non-spread data.
23. An access terminal, comprising:
at least one antenna;
a receiver configured to receive via the at least one antenna a spread data stream generated by spreading sub-blocks of data using a matrix with M orthogonal rows;
a combiner configured to combine sub-blocks of the received spread data stream, wherein the combination is based on the matrix with M orthogonal rows to generate M sets of combined spread sub-blocks;
a first circuit configured to generate, using a plurality of the combined spread sub-blocks of a first size, spread sub-blocks of a second size smaller than the first size; and
a second circuit configured to process the spread sub-blocks of the second size to obtain estimates of original non-spread data.