Receiving station with interference signal suppression

• US 6,285,861 B1
• Filed: 06/14/1999
• Issued: 09/04/2001
• Est. Priority Date: 06/14/1999
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Ling, Fuyun, Sindhushayana, Nagabhushana, Black, Peter, Bonaccorso, Mario
• Primary Examiner(s): Trost, William G.
• Assistant Examiner(s): Tran, Congvan
• Application Number:
  US09/332,857
• Time in Patent Office: 813 Days
• Field of Search: 455/425, 455/130, 455/132, 455/137-140, 455/151.4, 455/161.2, 455/186.1, 455/184.1, 455/234, 455/242.1, 455/242.2, 455/243.1, 455/271, 455/273 , 455/296, 375/346, 375/343, 375/348, 375/349, 375/350, 375/316
• US Class Current: 455/137
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers
• CPC Class Codes: H04B 1/712 Weighting of fingers for combining, e.g. amplitude control or phase rotation using an inner loop
• CPC Class Codes: H04B 7/0854 using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion

Abstract

An optimum combiner that reduces the amount of interference imposed upon a first base station by transmissions of other base stations within the same communication system. Two antennas are used to receive transmissions within a receiving station. A rake receiver is coupled to each antenna. By optimally combining the signals that are received by each independent finger of the rake receiver, interference that is correlated between a finger associated with the first antenna and a finger associated with the second antenna can be minimized with respect to the desired signal. Optimum combining requires determination of optimum combining coefficients.

Claims

1. An optimum combining processor, including:

a) a combiner coefficient processor, including;

i) a fading coefficient estimation module;

ii) a first interpolation module, coupled to the fading coefficient estimation module;

iii) an autocorrelation estimation module;

iv) a second interpolation module, coupled to the autocorrelation estimation module;

v) an inversion module, coupled to the interpolation module; and

vi) a combining coefficient evaluation module, coupled to the inversion module and to the first interpolation module; and

b) at least one optimum combiner, each optimum combiner coupled to the combiner coefficient processor and including;

i) a plurality of two input multiplication modules, each having an output, the first input of each multiplication module being configured to receive a signal from one of a plurality of fingers of a rake receiver, the second input of each multiplication module being coupled to the combining coefficient evaluation module to receive a combining coefficient; and

ii) a summing module having a number of inputs equal to the number of two input multiplication modules, each of the inputs being coupled to the output of a corresponding one of the multiplication modules.

2. The optimum combining coefficient processor of claim 1, wherein the autocorrelation estimation module is an R_yy autocorrelation module.

3. The optimum combining coefficient processor of claim 1, wherein the autocorrelation estimation module is an R_nn autocorrelation module.

4. An optimum combining processor, including:

a) a combiner coefficient processor, including;

i) a fading coefficient estimation module;

ii) an autocorrelation estimation module;

iii) an inversion module, coupled to the autocorrelation estimation module; and

iv) a combining coefficient evaluation module, coupled to the inversion module and to the first interpolation module;

v) an interpolation module, coupled to the evaluation module; and

b) at least one optimum combiner, each optimum combiner coupled to the interpolation module and including;

i) a plurality of two input multiplication modules, each having an output, the first input of each multiplication module being configured to receive a signal from one of a plurality of fingers of a rake receiver, the second input of each multiplication module being coupled to the interpolation module to receive a combining coefficient; and

ii) a summing module having a number of inputs equal to the number of two input multiplication modules, each of the inputs being coupled to the output of a corresponding one of the multiplication modules.

5. The optimum combining coefficient processor of claim 4, wherein the autocorrelation estimation module is an R_yy autocorrelation module.

6. The optimum combining coefficient processor of claim 4, wherein the autocorrelation estimation module is an R_nn autocorrelation module.

7. A receiving station, including:

a) a first antenna;

b) a first receiver module, coupled to the first antenna;

c) a second antenna;

d) a second receiver module, coupled to the second antenna;

e) an optimum combining processor, coupled to the first receiver module and to the second receiver module, the optimum combining processor including;

i) a combiner coefficient processor, including;

(1) a fading coefficient estimation module;

(2) a first interpolation module, coupled to the fading coefficient estimation module;

(3) an autocorrelation estimation module;

(4) a second interpolation module, coupled to the autocorrelation estimation module;

(5) an inversion module, coupled to the interpolation module; and

(6) a combining coefficient evaluation module, coupled to the inversion module and to the first interpolation module; and

ii) at least one optimum combiner, each optimum combiner coupled to the combiner coefficient processor and including;

(1) a plurality of two input multiplication modules, each having an output, the first input of each multiplication module being configured to receive a signal from one of a plurality of fingers of a rake receiver, the second input of each multiplication module being coupled to the combining coefficient evaluation module to receive a combining coefficient; and

(2) a summing module having a number of inputs equal to the number of two input multiplication modules, each of the inputs being coupled to the output of a corresponding one of the multiplication modules.

8. The receiving station of claim 7, wherein the autocorrelation estimation module is an R_yy autocorrelation module.

9. The receiving station of claim 7, wherein the autocorrelation estimation module is an R_nn autocorrelation module.

10. A receiving station, including:

a) a first antenna;

b) a first receiver module, coupled to the first antenna;

c) a second antenna;

d) a second receiver module, coupled to the second antenna; and

e) an optimum combining processor, coupled to the first receiver module and to the second receiver module, the optimum combining processor including;

i) a combiner coefficient processor, including;

(1) a fading coefficient estimation module;

(2) an autocorrelation estimation module;

(3) an inversion module, coupled to the autocorrelation estimation module; and

(4) a combining coefficient evaluation module, coupled to the inversion module and to the first interpolation module; and

(5) an interpolation module, coupled to the evaluation module; and

ii) at least one optimum combiner, each optimum combiner coupled to the interpolation module and including;

(1) a plurality of two input multiplication modules, each having an output, the first input of each multiplication module being configured to receive a signal from one of a plurality of fingers of a rake receiver, the second input of each multiplication module being coupled to the interpolation module to receive a combining coefficient; and

(2) a summing module having a number of inputs equal to the number of two input multiplication modules, each of the inputs being coupled to the output of a corresponding one of the multiplication modules.

11. The receiving station of claim 10, wherein the autocorrelation estimation module is an R_yy autocorrelation module.

12. The receiving station of claim 10, wherein the autocorrelation estimation module is an R_nn autocorrelation module.

13. A method for combining signals received at a receiving station, including the steps of:

a) receiving desired signals from a source over two antennas;

b) estimating a cross-correlation between the received desired signals and the symbols encoded in the received desired signals;

c) estimating an autocorrelation matrix;

d) calculating an optimum combining coefficient in response to estimating the cross-correlation and the autocorrelation matrix;

e) combining the desired signals using the optimum combining coefficient; and

f) calculating a signal to interference ratio of a result of combining the desired signals.