Method and system for adaptive signal processing for an antenna array

• US 6,232,921 B1
• Filed: 01/11/2000
• Issued: 05/15/2001
• Est. Priority Date: 01/11/2000
• Status: Expired due to Term

• Current Assignee: RPX Corporation
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Uptegrove, Dirck, Benning, Roger David, Aiken, Richard Thomas
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): PHAN, DAO LINDA
• Application Number:
  US09/481,567
• Time in Patent Office: 490 Days
• Field of Search: 342/378, 342/382, 342/383
• US Class Current: 342/383
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04B 7/0842 Weighted combining

Abstract

A method and system for adaptive signal processing for an antenna array reduces the requisite computations for executing an adaptive algorithm that combines or digitally filters baseband receive signals. The system receives uplink electromagnetic signals from a phased array and uplink electromagnetic signals from a diversity array during the reception of a desired electromagnetic signal transmitted by a desired mobile station. The uplink signals are converted into baseband signals for digital signal processing. The baseband signals are observable as a series of successive time slots. The system determines uplink coarse combining weights associated with the uplink baseband signals of the phased array and downlink coarse combining weights associated with the downlink baseband signals of the phased array. The baseband uplink signals are summed into as few as one resultant baseband signal during or after application of the coarse combining weights to the baseband uplink signals. The system determines fine combining weights for one or more resultant baseband signals and the baseband uplink signals on a symbol-by-symbol basis, or on any durational basis less than a time slot, to combine the signals into a single enhanced baseband signal for symbol detection.

Claims

1. A method for signal processing of signals associated with an antenna array;

the method comprising;

converting M and N uplink electromagnetic signals from a phased array and a diversity array, respectively, into uplink baseband signals for digital signal processing, the uplink baseband signals being observable as a series of successive time slots, where M and N are positive integers;

applying M coarse combining weights to combine the uplink baseband signals associated with the phased array on a time slot by time slot basis;

summing the weighted M, uplink baseband signals of the phased array into at least one resultant baseband signal; and

determining fine combining weights for the at least one resultant uplink signal and the N uplink signals to form a single receive channel for subsequent symbol detection, the fine combining weights applying to a duration less than one of the time slots.

2. The method according to claim 1 further comprising the step of:

receiving the M uplink electromagnetic signals from the phased array and the N uplink signals from the diversity array, the phased array having adjacent columns with separations of less than or equal to one wavelength at the frequency of operation, and the diversity array having cross-polarized antenna elements.

3. The method according to claim 1 further comprising the step of:

receiving the M uplink electromagnetic signals from the phased array and the N uplink signals from the diversity array, the phased array having adjacent columns with separations of less than or equal to one wavelength at the frequency of operation, and the diversity array having greater separations between adjacent columns than the phased array.

4. The method according to claim 1 further comprising the step of:

receiving the M uplink electromagnetic signals from the phased array and the N uplink signals from the diversity array, the phased array being separated from the diversity array within a range from five wavelengths to twenty wavelengths at the frequency of operation.

5. The method according to claim 1 further comprising the step of providing a phased array having separations between adjacent antenna elements that yield a coherent response to a receive signal incident upon the phased array.

6. The method according to claim 1 wherein the determining step comprises determining the fine combining weights on a symbol by symbol basis, wherein multiple symbols are associated with each of the time slots.

7. The method according to claim 1 wherein the applying step further includes applying M downlink coarse combining weights to combine the downlink baseband signals associated with the phased array.

8. The method according to claim 1 wherein the applying step further includes applying M downlink coarse combining weights and M uplink coarse combining weights for subsequent downlink time slots and uplink time slots, respectively, the M coarse combining weights being temporally related to an earlier time slot of an uplink baseband signal.

9. The method according to claim 1 further comprising the step of:

determining the M coarse combining weights for subsequent time slots based on earlier time slots of the uplink baseband signals from the phased array.

10. The method according to claim 1 wherein the applying step further comprises applying M downlink coarse combining weights to subsequent downlink time slots based on analysis of previous uplink time slots of the uplink electromagnetic signals from the phased array.

11. The method according to claim 1 wherein the applying step comprises applying M uplink coarse combining weights, derived from earlier time slots, to subsequent next uplink time slots immediately following the earlier time slots.

12. The method according to claim 1 wherein summing step produces m resultant baseband signals, where m is greater than one and less than M, M is the total number of columns in the phased array, and N is the total number of columns in the diversity array.

13. The method according to claim 1 wherein the summing step includes preparing the uplink baseband signals for application to an adaptive signal processing algorithm by reducing the computational load associated with the adaptive signal processing algorithm by a factor of (m+N)²/(M+N)², where M is the total number of columns of antenna elements in the phased array, N is the total number of columns of antenna elements in the diversity array, m is the number of the at least one resultant baseband signal, and 1≦

m<

M.

14. A method for signal processing of signals associated with an antenna array;

the method comprising;

converting the M and N uplink electromagnetic signals from a phased array and a diversity array, respectively, into uplink baseband signals for digital signal processing, the uplink baseband signals being observable as a series of successive time slots;

applying M coarse combining weights to combine the uplink baseband signals associated with the phased array on a time slot by time slot basis; and

preparing the uplink baseband signals for application to an adaptive signal processing algorithm by reducing the computational load associated with the adaptive signal processing algorithm by a factor of (m+N)²/(M+N)², where M is the total number of columns of antenna elements in the phased array, N is the total number of columns of antenna elements in the diversity array, and m is the number of the at least one resultant baseband signal, and 1≦

m<

M.

15. The method according to claim 14 further comprising the step of:

determining fine combining weights for the one resultant uplink signal and the N uplink signals to form a single receive channel for subsequent symbol detection, the fine combining weights applying to a duration less than one of the time slots.

16. The method according to claim 14 wherein the preparing step comprises summing the weighted M baseband uplink signals of phased array into as few as one resultant baseband signal.

17. The method according to claim 14 further comprising applying the fine combining weights to decode symbols while achieving diversity gain and interference reduction.

18. A system for signal processing of signals associated with an antenna array;

the system comprising;

a downconverter for converting the M and N uplink electromagnetic signals from a phased array and a diversity array, respectively, into uplink baseband signals for digital signal processing, the uplink baseband signals being organized into a plurality of successive time slots;

an uplink filtering weight manager for applying M coarse combining weights for one or more time slots to filter the uplink baseband signals associated with the phased array;

a summer for summing the weighted M baseband uplink signals of phased array into at least one resultant baseband signal; and

an uplink adaptive baseband signal processor for determining fine combining weights for the at least one resultant uplink signal and the N uplink signals on a symbol by symbol basis, wherein multiple symbols are associated with each time slot.

19. The system according to claim 18 wherein the phased array has adjacent columns of antenna elements with separations of less than or equal to approximately one-half wavelength at the frequency of operation and the diversity array having cross-polarized antenna elements.

20. The system according to claim 18 wherein the phased array has adjacent columns of antenna elements with separations of less than or equal to one wavelength at the frequency of operation and the diversity array having greater separations between adjacent columns than the phased array.

21. The system according to claim 18 wherein the phased array and the diversity array are separated within a range from five wavelengths to twenty wavelengths at the frequency of operation.

22. The system according to claim 18 wherein the phased array has separations between adjacent antenna elements that yield a coherent response to a receive signal incident upon the phased array.

23. The system according to claim 18 wherein the summer reduces the computational load associated with the adaptive signal processing algorithm by a factor of (1+N)²/(M+N)², where M is the total number of columns of antenna elements in the phased array and N is the total number of columns of antenna elements in the diversity array.

24. The system according to claim 18 wherein the summer reduces the computational load associated with the adaptive signal processing algorithm by a factor as small as (m+N)²/(M+N)², where M is the total number of columns of antenna elements in the phased array, N is the total number of columns of antenna elements in the diversity array, and m is the number of the at least one resultant baseband signal, and 1≦

m<

M.