Methods, computer program products and apparatus providing low complexity determination of cross-correlations
View Patent ↗The exemplary embodiments of the invention provide methods, computer program products and apparatus for determining cross-correlations between the received signals in a set of users. An exemplary method includes: receiving an input signal comprising a plurality of user signals, selecting a first received signal and a second received signal from the plurality of user signals, determining a timing offset between the first signal and the second signal, and using the determined timing offset, a first identification of the first signal, and a second identification of the second signal as indices to retrieve at least one cross-correlation coefficient from a memory.
1. A method comprising:
receiving, by an apparatus, an input signal comprising a plurality of received signals;
selecting, by the apparatus, a first received signal and a second received signal from said plurality of received signals;
determining, by the apparatus, a timing offset between said first signal and said second signal; and
using, by the apparatus, said determined timing offset, a first identification of said first signal, and a second identification of said second signal as indices to retrieve at least one cross-correlation coefficient.
2. The method of claim 1 , wherein the at least one cross-correlation coefficient is retrieved from a look-up table.
3. The method of claim 1 , wherein said timing offset is rounded to an integer timing offset value.
4. The method of claim 3 , wherein said at least one cross-correlation coefficient comprises a first cross-correlation coefficient and a second cross-correlation coefficient.
5. The method of claim 4 , further comprising:
interpolating between said first cross-correlation coefficient and said second cross-correlation coefficient using said timing offset and said integer timing offset value to obtain an interpolated cross-correlation value.
6. The method of claim 5 , wherein said interpolating comprises applying at least one of a linear function, a cubic spline, and a raised cosine function.
7. The method of claim 1 , wherein the first identification comprises a first PN code identifier corresponding to the first received signal and the second identification comprises a second PN code identifier corresponding to the second received signal.
8. A computer-readable memory storing program instructions, execution of the program instructions by an apparatus resulting in operations comprising:
receiving an input signal comprising a plurality of received signals;
selecting a first received signal and a second received signal from said plurality of received signals;
computing a timing offset between said first signal and said second signal; and
using said timing offset, a first identification of said first signal, and a second identification of said second signal as indices to retrieve at least one cross-correlation coefficient.
9. The computer-readable memory of claim 8 , wherein the at least one cross-correlation coefficient is retrieved from a look-up table.
10. The computer-readable memory of claim 8 , wherein said timing offset is rounded to an integer timing offset value.
11. The computer-readable memory of claim 10 , wherein said at least one cross-correlation coefficient comprises a first cross-correlation coefficient and a second cross-correlation coefficient.
12. The computer-readable memory of claim 11 , further comprising:
interpolating between said first cross-correlation coefficient and said second cross-correlation coefficient using said timing offset and said integer timing offset value to obtain an interpolated cross-correlation value.
13. The computer-readable memory of claim 12 , wherein said interpolating comprises applying at least one of a linear function, a cubic spline, and a raised cosine function.
14. The computer-readable memory of claim 8 , wherein the first identification comprises a first PN code identifier corresponding to the first received signal and the second identification comprises a second PN code identifier corresponding to the second received signal.
15. An apparatus comprising:
means for receiving an input signal comprising a plurality of received signals;
means for selecting a first received signal and a second received signal from said plurality of received signals;
means for computing a timing offset between said first signal and said second signal; and
means for using said timing offset, a first identification of said first signal, and a second identification of said second signal as indices to retrieve at least one cross-correlation coefficient.
16. The apparatus of claim 15 , wherein the at least one cross-correlation coefficient is retrieved from a look-up table.
17. The apparatus of claim 15 , wherein said timing offset is rounded to an integer timing offset value, wherein said at least one cross-correlation coefficient comprises a first cross-correlation coefficient and a second cross-correlation coefficient, wherein the apparatus further comprises:
means for interpolating between said first cross-correlation coefficient and said second cross-correlation coefficient using said timing offset and said integer timing offset value to obtain an interpolated cross-correlation value.
18. An apparatus comprising:
a multiplexer configured to select a first received signal and a second received signal from a plurality of received signals;
a timing circuit configured to compute a timing offset between said first signal and said second signal; and
a processor configured to retrieve at least one cross-correlation coefficient by using as indices said timing offset, a first identification identifying said first signal, and a second identification identifying said second signal.
19. The apparatus of claim 18 , wherein said timing offset is rounded to an integer timing offset value.
20. The apparatus of claim 19 , wherein said at least one cross-correlation coefficient comprises a first cross-correlation coefficient and a second cross-correlation coefficient.
21. The apparatus of claim 20 , further comprising:
an interpolator configured to interpolate between said first cross-correlation coefficient and said second cross-correlation coefficient using said timing offset and said integer timing offset value to obtain an interpolated cross-correlation value.
22. The apparatus of claim 21 , wherein said interpolating further comprises applying at least one of a linear function, a cubic spline, and a raised cosine function.
23. The apparatus of claim 18 , wherein the first identification comprises a first PN code identifier corresponding to the first received signal and the second identification comprises a second PN code identifier corresponding to the second received signal.
24. The apparatus of claim 18 , further comprising a memory, wherein the at least one cross-correlation coefficient is stored in said memory as part of a look-up table.