Closed Form Calculation of Temporal Equalizer Weights Used in a Repeater Transmitter Leakage Cancellation System

• US 20080225929A1
• Filed: 03/03/2008
• Published: 09/18/2008
• Est. Priority Date: 03/02/2007
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Otto, James C., Gainey, Kenneth M., Proctor, James A.
• Granted Patent: US 8,599,906 B2
• Time in Patent Office: Days
• US Class Current: 375/214
• CPC Class Codes: H04B 7/15542 Selecting at relay station its transmit and receive resources selection of wireless resources by user or terminal H04W72/02; arrangements affording multiple use of the transmission path by two-dimensional division of the resources H04L5/0003, or by allocating sub-channels H04L5/003
• CPC Class Codes: H04B 7/15571 by signal isolation, e.g. isolation by frequency or by antenna pattern, or by polarization
• CPC Class Codes: H04B 7/15585 by interference cancellation

Abstract

A repeater environment is provided to operatively deploy a feedback cancellation loop that performs closed loop calculations for weights used by a feedback equalizer to improve signal integrity and amplification. In an illustrative implementation, an exemplary repeater environment comprises a transmitter, a receiver, an equalized feedback cancellation loop circuitry operative to perform one or more closed form calculations for equalizer weights. In the illustrative implementation, the feedback cancellation loop can comprise a calculation module operative to perform one or more closed form weight calculations using linear algebraic techniques as part of feedback signal cancel operations for use by the N tap feedback equalizer canceller.

Claims

1. A repeater for a wireless communication network, the repeater operative to provide feedback cancellation, the repeater comprising:

a calculation module configured to perform closed form calculations for equalizer weights, wherein samples of a transmitter and/or receiver signal are stored as part of the closed form calculations; and

an equalized feedback cancellation loop comprising an equalizer cooperating with the calculation model to generate at least the equalizer weights for use in one or more operations to provide signal cancellation and isolation.

2. The repeater as recited in claim 1, wherein the equalizer includes N taps, wherein N is greater than or equal to one, and wherein the equalizer weights comprise equalizer tap weights.

3. The repeater as recited in claim 1, wherein the closed form calculations comprise minimum mean squared error (MMSE) calculations.

4. The repeater as recited in claim 1, further comprising one or more analog to digital converters operative to sample an input signal to the repeater.

5. The repeater as recited in claim 4, further comprising a digital to analog converter operative to modulate a signal provided by the equalized feedback cancellation loop into an RF signal.

6. The repeater as recited in claim 1, wherein the repeater is a Time Division Duplex repeater and the wireless communication network is one of a Wireless-Fidelity (Wi-Fi), and Worldwide Interoperability for Microwave Access (Wi-max) network.

7. The repeater as recited in claim 1, wherein the repeater is a Frequency Division Duplex repeater and the wireless communication network is one of a cellular, Global System for Mobile communications (GSM), Code Division Multiple Access (CDMA), and ThirdGeneration (3G) network.

8. The repeater as recited in claim 1, further comprising one or more reception and/or transmission antennas, wherein the reception and/or transmission antennas including one or more dipole antennas, one or more patch antennas, or a combination thereof.

9. The repeater as recited in claim 1, wherein the calculation module comprises digital logic to manage, control, monitor, and direct the calculation of the equalizer weights.

10. The repeater as recited in claim 1, wherein the calculation module is configured to perform the closed form calculations by executing a linear algebra algorithm comprising at least one algorithm selected from the group consisting of a minimum mean squared error (MMSE) algorithm, a maximum signal-to-noise ration algorithm, and a linear constrained minimum variance algorithm.

11. A method to facilitate feedback loop cancellation in a digital repeater environment comprising:

storing a receive signal from a receiver;

processing the receive signal to produce a signal to be transmitted;

passing samples of the signal to be transmitted to a transmitter and a first-in-first-out (FIFO) delay line in parallel;

adding a selected time delay to the samples passed to the FIFO delay line by an amount equal to a total delay from a FIFO input location through transmission processing minus an amount equal to a feedback cancellation loop'"'"'s equalizer sample delay to generate FIFO delayed transmit reference signal;

passing samples of the FIFO delayed transmit reference signal to a memory as a selected matrix u;

generating a correlation matrix R from the stored samples of the FIFO delayed transmit reference signal;

generating a cross correlation array p derived from correlating the delayed transmitter reference signal with receive signal resulting in an array p having a selected dimension; and

calculating equalizer tap weights using the inverse of R matrix and the array p.

12. The method as recited in claim 11, further comprising storing the FIFO delayed transmit reference signal are stored in memory.

13. The method as recited in claim 12, further comprising an equalizer having N taps where N is greater than or equal to one.

14. The method as recited in claim 13, further comprising providing an adaptive antenna array for cooperation with the equalizer to generate a correlation metric.

15. The method as recited in claim 11, further comprising transmitting the equalizer tap weights from the equalizer to a receiver of the repeater.

16. The method as recited in claim 11, further comprising storing the FIFO delayed transmit signal as u (1,1) to u(N,1), wherein u(k,1) be represented as matrix of N delayed versions of a L transmitted time samples, wherein each of the N delayed versions are delayed by the same amount as the delay between the taps of an equalizer.

17. The method as recited in claim 16, further comprising producing correlation matrix R from the u matrix wherein the u matrix has a dimension N×

L and is processed according to a Hermitian transpose to result in an N×

N matrix.

18. The method as recited in claim 11, further comprising calculating the equalizer tap weights according to one or more closed form linear algebra algorithms comprising MMSE, MaxSNR, and LCMZV algorithms.

19. The method as recited in claim 18, further comprising utilizing the closed form linear algebra algorithm in conjunction with a leakage correlation metric.

20. The method as recited in claim 18, further comprising utilizing the closed form linear algebra algorithm in conjunction with an adaptive algorithm.

21. A repeater for a wireless communication network, the repeater operative to provide feedback cancellation, the repeater comprising:

means for performing closed loop calculations for weights used by an equalizer, wherein samples of the transmitter and/or receiver signal are stored as part of closed loop calculations; and

means for generating weights for use in one or more correlation operations to provide signal cancellation and isolation.

22. A computer readable medium having stored thereon computer executable instructions for performing the following acts:

passing samples of the signal to be transmitted to a transmitter and a first-in-first-out (FIFO) delay line in parallel;

adding a selected time delay to the FIFO samples by an amount equal to the total delay from the FIFO input location through transmission processing minus an amount equal to a feedback cancellation loop'"'"'s equalizer sample delay to generate FIFO delayed transmit reference signal;

passing samples of the FIFO delayed transmit reference signal to a memory as a selected matrix u;

generating a correlation matrix R from the stored FIFO delayed transmit reference signal samples;

generating a cross correlation vector p derived in part from the stored FIFO delayed transmit signal samples resulting in an array p having a selected dimension; and

calculating equalizer tap weights using the inverse of R matrix and the array p.

23. A processor comprising a memory having stored thereon computer executable instructions that cause the processor to perform the following acts:

passing samples of the signal to be transmitted to a transmitter and a first-in-first-out (FIFO) delay line in parallel;

adding a selected time delay to the FIFO samples by an amount equal to the total delay from the FIFO input location through transmission processing minus an amount equal to a feedback cancellation loop'"'"'s equalizer sample delay to generate FIFO delayed transmit reference signal;

passing samples of the FIFO delayed transmit reference signal to the memory as a selected matrix u;

generating a correlation matrix R from the stored FIFO delayed transmit reference signal samples;

generating a cross correlation vector p derived in part from the stored transmit signal resulting in an array p having a selected dimension; and

calculating equalizer tap weights using the inverse of R matrix and the array p.