Cluster path processor time alignment for signal suppression/separation in a wireless device

• US 20080075216A1
• Filed: 03/29/2007
• Published: 03/27/2008
• Est. Priority Date: 09/21/2006
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Chung, Li Fung, Hahm, Mark David, Kong, Hongwei, Li, Junqiang, Sollenberger, Nelson R.
• Granted Patent: US 7,697,596 B2
• Time in Patent Office: Days
• US Class Current: 375/355
• CPC Class Codes: H04B 1/7085 using a code tracking loop, e.g. a delay-locked loop
• CPC Class Codes: H04B 1/7117 Selection, re-selection, allocation or re-allocation of paths to fingers, e.g. timing offset control of allocated fingers
• CPC Class Codes: H04L 7/0054 Detection of the synchronisation error by features other than the received signal transition by means of signal transition H04L7/033
• CPC Class Codes: H04L 7/007 detection of error based on maximum signal power, e.g. peak value, maximizing autocorrelation
• CPC Class Codes: H04L 7/033 using the transitions of the received signal to control the phase of the synchronising-signal-generating means, e.g. using a phase-locked loop

Abstract

A system for processing radio frequency (RF) signals includes a searcher and a plurality of Cluster Path Processor (CPPs). The searcher detects a maximum signal energy level and position of at least one of a plurality of individual distinct path signals in a signal cluster of a first information signal, wherein at least a portion of the plurality of individual distinct path signals is received within a duration of a corresponding delay spread. The sampling position is used as a starting sampling location by the plurality of CPPs, including a first information signal CPP and a second information signal CPP. Fine sampling positions of the plurality of CPPs are based upon channel energy estimates for the plurality of individual distinct path signals. CPP outputs are employed to produce channel estimates, which are themselves used in subsequent equalization operations. Sampling positions may change over time in order to satisfy alignment criteria.

Claims

1. A method for operating a Radio Frequency (RF) receiver to process a composite information signal having a first information signal and a second information signal, the method comprising:

for a first information signal group finger array that is operable to receive a plurality of individual distinct signal paths of a first information signal cluster that is received within a duration of a corresponding delay spread;

at a first time, receiving a timing reference signal corresponding to the first information signal and locking a delay locked loop based upon the timing reference signal;

at the first time, establishing a delay locked loop sampling position of the first information signal group finger array based upon the timing reference signal; and

at second and subsequent times, based upon early and late signal correlation values with the first information signal, adjusting the delay locked loop sampling position of the first information signal group finger array; and

for a second information signal group finger array that is operable to receive a plurality of individual distinct signal paths of a second information signal cluster that is received within a duration of a corresponding delay spread;

at the first time, determining a sampling position offset of the second information signal with respect to the first information signal;

at the first time and subsequent times, aligning the second information signal group finger array based upon the delay locked loop sampling position and the sampling position offset.

2. The method of claim 1, wherein:

the first information signal includes data intended for the RF receiver;

the second information signal is an interfering signal; and

the sampling position offset is non-zero.

3. The method of claim 1, further comprising:

determining a first information signal pseudo noise (PN) correlation position for PN correlation with the first information signal by the first group finger array; and

determining a second information signal PN correlation position for use in PN correlation with the second information signal by the second group finger array with respect to the sampling position of the first information signal group finger array and the relative frame offset between the first information signal and the second information signal.

4. The method of claim 1, wherein in establishing a delay locked loop sampling position of the first information signal group finger array based upon the timing reference signal, a selected finger of the first information signal group finger array is aligned with a strongest path of the first information signal.

5. The method of claim 1, further comprising:

the first information signal group finger array producing a first channel estimate for the first information signal;

the second information signal group finger array producing a second channel estimate for the second information signal; and

a first channel estimate output time of the first channel estimate by the first information signal group finger array is also used as a second channel estimate output time of the second channel estimate by the second information signal group finger array.

6. The method of claim 5, further comprising processing the composite information signal by:

determining equalizer coefficients based upon the first channel estimate and the second channel estimate;

equalizing the composite information signal to remove the second information signal; and

extracting data of the first information signal from the equalized composite information signal.

7. A method for operating a Radio Frequency (RF) receiver to process a composite information signal having a first information signal and a second information signal, the method comprising:

for a first information signal group finger array that is operable to receive a plurality of individual distinct signal paths of a first information signal cluster that is received within a duration of a corresponding delay spread and for a second information signal group finger array that is operable to receive a plurality of individual distinct signal paths of a second information signal cluster that is received within a duration of a corresponding delay spread;

at a first time, receiving a timing reference signal corresponding to the first information signal and a timing reference signal corresponding to the second information signal and locking a delay locked loop based upon both timing reference signals;

at the first time, establishing a delay locked loop sampling position of the first information signal group finger array and the second information signal group finger array based upon the timing reference signals; and

at second and subsequent times, based upon early and late signal correlation values with the first information signal and the second information signal, adjusting the delay locked loop sampling position of the first information signal group finger array and the second information signal group finger array.

8. The method of claim 7, wherein:

the first information signal includes first data intended for the RF receiver;

the second information signal includes second data intended for the RF receiver;

the first information signal and the second information signal are transmit diversity signals; and

the sampling position offset between the first information signal and second information signal is non-zero.

9. The method of claim 7, wherein:

the first information signal includes first data intended for the RF receiver;

the second information signal includes second data intended for the RF receiver;

the first information signal and the second information signal are receive diversity signals; and

the sampling position offset between the first information signal and second information signal is zero.

10. The method of claim 7, further comprising:

determining a first information signal pseudo noise (PN) correlation position for PN correlation with the first information signal by the first group finger array; and

determining a second information signal PN correlation position for use in PN correlation with the second information signal by the second group finger array.

11. The method of claim 7, wherein in establishing a delay locked loop sampling position of the first information signal group finger array and the second information signal group finger array based upon the timing reference signals, a selected finger pair, one of the first information signal group finger array and the other of the second information signal group finger array, is aligned with a strongest path pair, one of the first information signal and the other of the second information signal.

12. The method of claim 7, further comprising:

the first information signal group finger array producing a first channel estimate for the first information signal;

the second information signal group finger array producing a second channel estimate for the second information signal; and

a first channel estimate output time of the first channel estimate output by the first information signal group finger array is the same as a second channel estimate output time of the second channel estimate output by the second information signal group finger array.

13. The method of claim 12, further comprising processing the composite information signal by:

determining equalizer coefficients based upon the first channel estimate and the second channel estimate;

equalizing a first copy of the composite information signal to remove the second information signal;

extracting data of the first information signal from the equalized first copy of the composite information signal;

equalizing a second copy of the composite information signal to remove the first information signal; and

extracting data of the second information signal from the equalized second copy of the composite information signal.

14. The method of claim 13, further comprising Space Time Transmit Diversity (STTD) combining the data of the first information signal with the data of the second information signal.

15. The method of claim 12, further comprising processing the composite information signal by:

determining equalizer coefficients based upon the first channel estimate;

equalizing a first copy of the composite information signal;

extracting data of the first information signal from the equalized first copy of the composite information signal;

determining equalizer coefficients based upon the second channel estimate;

equalizing a second copy of the composite information signal; and

extracting data of the second information signal from the equalized second copy of the composite information signal.

16. The method of claim 15, further comprising Receive Diversity combining the data of the first information signal with the data of the second information signal.

17. A method for operating a Radio Frequency (RF) receiver to process a composite information signal having first, second, third, fourth, fifth, and sixth information signals, the method comprising:

for a first information signal group finger array that is operable to receive a plurality of individual distinct signal paths of a first information signal cluster that is received within a duration of a corresponding delay spread and for a second information signal group finger array that is operable to receive a plurality of individual distinct signal paths of a second information signal cluster that is received within a duration of a corresponding delay spread;

at a first time, receiving a timing reference signal corresponding to the first information signal and a timing reference signal corresponding to the second information signal and locking a delay locked loop based upon both timing reference signals;

at the first time, establishing a delay locked loop sampling position of the first information signal group finger array and the second information signal group finger array based upon the timing reference signals; and

at second and subsequent times, based upon early and late signal correlation values with the first information signal and the second information signal, adjusting the delay locked loop sampling position of the first information signal group finger array and the second information signal group finger array; and

for third, fourth, fifth and sixth information signal group finger arrays that are operable to respectively receive a plurality of individual distinct signal paths of signal clusters of the third, fourth, fifth and sixth information signals, that are received within respective durations of corresponding delay spreads;

at the first time, determining sampling position offsets for the third, the fourth, the fifth and the sixth information signals with respect to the delay locked loop sampling position;

at the first time and subsequent times, aligning the third, fourth, fifth and sixth information signal group finger arrays respectively based upon respective delay locked loop sampling position offsets.

18. The method of claim 17, wherein:

the first information signal includes first data intended for the RF receiver;

the second information signal includes second data intended for the RF receiver;

the first information signal and the second information signal are receive diversity signals; and

the sampling position offset between the first information signal and the second information signal is zero.

19. The method of claim 17, wherein:

the third and the fourth information signals are interfering signals;

the third and the fourth information signals are receive diversity signals; and

the sampling position offset between the first information signal and the third information signal is non-zero; and

the sampling position offset between the third information signal and the fourth information signal is zero.

20. The method of claim 17, wherein:

the fifth and the sixth information signals are interfering signals;

the fifth and the sixth information signals are receive diversity signals; and

the sampling position offset between the first information signal and the fifth information signal is non-zero;

the sampling position offset between the fifth information signal and the sixth information signal is zero.

21. The method of claim 17, further comprising:

determining a first information signal pseudo noise (PN) correlation position for PN correlation with the first information signal by the first group finger array and the second information signal by the second group finger array; and

determining a third information signal PN correlation position for use in PN correlation with the third information signal by the third group finger array and the fourth information signal by the fourth group finger array, with respect to the sampling position of the first information signal group finger array and the frame offset between the third information signal and the first information signal; and

determining a fifth information signal PN correlation position for use in PN correlation with the fifth information signal by the fifth group finger array and the sixth information signal by the sixth group finger array, with respect to the sampling position of the first information signal group finger array and the frame offset between the fifth information signal and the first information signal.

22. The method of claim 17, wherein in establishing a delay locked loop sampling position of the first information signal group finger array and the second information signal group finger array based upon the timing reference signals, a selected finger pair, one of the first information signal group finger array and the other of the second information signal group finger array is aligned with a strongest path pair, one of the first information signal and the other of the second information signal.

23. The method of claim 17, further comprising:

the first, the second, the third, the fourth, the fifth and the sixth information signal group finger arrays producing respectively a first, a second, a third, a fourth, a fifth, and a sixth channel estimate for the respective first, second, third, fourth, fifth, and sixth information signal; and

a first channel estimate output time of the first channel estimate output by the first information signal group finger array is the same as a second, a third, a fourth, a fifth, and a sixth channel estimate output time of the respective second, third, fourth, fifth, and sixth channel estimate output by the respective second, third, fourth, fifth, and sixth information signal group finger array.

24. The method of claim 23, further comprising processing the composite information signal by:

determining equalizer coefficients based upon the first channel estimate, the third channel estimate, and the fifth channel estimates;

equalizing a first copy of the composite information signal to remove the third and the fifth information signals;

extracting data of the first information signal from the equalized first copy of the composite information signal; and

determining equalizer coefficients based upon the second channel estimate, the fourth channel estimate, and the sixth channel estimates;

equalizing a second copy of the composite information signal to remove the fourth and the sixth information signals;

extracting data of the second information signal from the equalized second copy of the composite information signal.

25. The method of claim 24, further comprising Receive Diversity combining the data of the first information signal with the data of the second information signal.

26. A method for operating a Radio Frequency (RF) receiver to process a composite information signal having a first information signal, a second information signal, a third information signal, and a fourth information signal, the method comprising:

for first, second, third, and fourth information signal group finger array that are operable to receive respective pluralities of individual distinct signal paths of first, second, third and fourth information signal clusters that are received within respective durations of corresponding delay spreads;

at a first time, receiving a timing reference signal corresponding to the first information signal, a timing reference signal corresponding to the second information signal, a timing reference signal corresponding to the third information signal, and a timing reference signal corresponding to the fourth information signal and locking a delay locked loop based upon all four timing reference signals;

at the first time, establishing a single delay locked loop sampling position of the first, the second, the third and the fourth information signal group finger arrays based upon the timing reference signals; and

at second and subsequent times, based upon early and late signal correlation values with the first, the second, the third and the fourth information signals, adjusting the delay locked loop sampling position of the first, the second, the third, and the fourth information signal group finger arrays.

27. The method of claim 26, wherein:

the first, second, the third and the fourth information signals include respective first, second, third and fourth data intended for the RF receiver;

the first information signal and the second information signals are receive diversity signals;

the third information signal and the fourth information signals are receive diversity signals;

the first information signal and the third information signals are transmit diversity signals;

the second information signal and the fourth information signals are transmit diversity signals; and

the sampling position offset between any two information signals is zero.

28. The method of claim 26, further comprising:

determining a first information signal pseudo noise (PN) correlation position for PN correlation with the first information signal by the first group finger array and the second information signal by the second group finger array; and

determining a third information signal pseudo noise (PN) correlation position for PN correlation with the third information signal by the third group finger array and the fourth information signal by the fourth group finger array.

29. The method of claim 26, wherein in establishing a delay locked loop sampling position of the four information signal group finger arrays based upon the timing reference signals, a selected finger combination of four fingers, one from each of the first, the second, the third and the fourth information signal group finger arrays is aligned with a strongest path combination, one path each of the first, the second, the third, and the fourth information signals.

30. The method of claim 26, further comprising:

the first, the second, the third, and the fourth information signal group finger array producing respectively a first, a second, a third, and a fourth channel estimate for the respective first, second, third, and fourth information signal; and

a first channel estimate output time of the first channel estimate output by the first information signal group finger array is the same as a second, a third, and a fourth channel estimate output time of the respective second, third, and fourth channel estimate output by the respective second, third, and fourth information signal group finger array.

31. The method of claim 30, further comprising processing the composite information signal by:

determining equalizer coefficients based upon the first channel estimate and the third channel estimate;

equalizing a first copy of the composite information signal to remove the third information signal;

extracting data of the first information signal from the equalized first copy of the composite information signal;

equalizing a second copy of the composite information signal to remove the first information signal;

extracting data of the third information signal from the equalized second copy of the composite information signal;

determining equalizer coefficients based upon the second channel estimate and the fourth channel estimate;

equalizing a third copy of the composite information signal to remove the fourth information signal;

extracting data of the second information signal from the equalized third copy of the composite information signal;

equalizing a fourth copy of the composite information signal to remove the second information signal; and

extracting data of the fourth information signal from the equalized fourth copy of the composite information signal.

32. The method of claim 31, further comprising:

receive Diversity combining the data of the first information signal with the data of the second information signal to get the receive combined first information signal; and

receive Diversity combining the data of the third information signal with the data of the fourth information signal to get the receive combined third information signal

33. The method of claim 32, further comprising Transmit Diversity (STTD) combining the data of the received combined first information signal with the data of the receive combined second information signal.

34. A system for processing a radio frequency (RF) composite information signal having a first information signal and a second information signal, the system comprising:

a searcher that detects a maximum signal energy level path of the first information signal and produces a timing reference signal based thereupon;

a delay locked loop operable to receive the timing reference signal and to lock based upon the timing reference signal;

a first information signal group finger array that is operable to receive a plurality of individual distinct signal paths of a first information signal cluster that is received within a duration of a corresponding delay spread and;

at the first time, lock the sampling position of the first information signal group finger array to the delay locked loop; and

at second and subsequent times, based upon early and late signal correlation values with the first information signal, adjust the delay locked loop to thereby adjust the sampling position of the first information signal group finger array; and

a second information signal group finger array that is operable to receive a plurality of individual distinct signal paths of a second information signal cluster that is received within a duration of a corresponding delay spread and;

at the first time, determine a sampling position offset of the second information signal with respect to the first information signal;

at the first time and subsequent times, lock sampling of the second information signal group finger array to the delay locked loop with the sampling position offset.

35. The system of claim 34, wherein when the first information signal group finger array and the second information signal group finger array provide receive path diversity operations for a non-transmit diversity signal, the sampling position offset is zero.

36. The system of claim 34, wherein when the first information signal group finger array and the second information signal group finger array provide receive path diversity operations for a transmit diversity signal, the sampling position offset is non-zero.

37. The system of claim 34, further wherein:

the first information signal group finger array produces a first channel estimate for the first information signal;

the second information signal group finger array produces a second channel estimate for the second information signal; and

a first channel output time of the first channel output by the first information signal group finger array differs from a second channel output time of the second channel output by the second information signal group finger array.

38. The system of claim 37, further comprising:

equalizer coefficient determination circuitry operable to process the composite information signal to determine equalizer coefficients based upon the first channel estimate and the second channel estimate;

equalizer circuitry operable to equalize the composite information signal to remove the second information signal; and

channel processing circuitry operable to extract data of the first information signal from the equalized composite information signal.

39. The system of claim 37, further comprising Space Time Transmit Diversity (STTD) circuitry operable to combine the data of the first information signal with the data of the second information signal.