Mobile telecommunication repeater for canceling feedback signals

• US 10,305,575 B2
• Filed: 03/15/2013
• Issued: 05/28/2019
• Est. Priority Date: 01/08/2013
• Status: Active Grant

• Current Assignee: Advanced RF Technologies Incorporated
• Original Assignee: Advanced RF Technologies Incorporated
• Inventors: Kim, Jong-Min
• Primary Examiner(s): Pan, Yuwen
• Assistant Examiner(s): Tran, Paul P
• Application Number:
  US13/841,447
• Publication Number:
  US 20140194054A1
• Time in Patent Office: 2,265 Days
• Field of Search: 455 1, 455 7, 455 9, 455 10, 455 111, 455 15, 455 16, 455 17, 455 18, 455 19, 455 20, 455 21, 455 22, 455 23, 455 24, 4552261, 4552341, 330149, 342198, 34235736, 348735, 370 75, 370 97, 370226, 370274, 370278, 370279, 370293, 370315, 370328, 370492, 370501, 375211, 375213, 375214, 375215, 375224, 375297, 375319, 375343
• CPC Class Codes: H01Q 1/007 specially adapted for indoor communication
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H01Q 3/2611 Means for null steering; Adaptive interference nulling
• CPC Class Codes: H03M 1/1052 using two or more look-up tables each corresponding to a different type of error, e.g. for offset, gain error and non-linearity error respectively
• CPC Class Codes: H04B 7/15507 Relay station based processing for cell extension or control of coverage area, network planning with network coordinated processing with regard to cell extension H04W16/26; network topologies using dedicated repeater stations H04W84/047; terminal devices adapted for relaying to or from an other terminal H04W88/04
• CPC Class Codes: H04B 7/15535 Control of relay amplifier gain amplifier gain control in general H03G3/00; gain control reducing self - or loop interference H04B7/15578
• 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
• CPC Class Codes: H04L 25/24 Relay circuits using discharge tubes or semiconductor devices H04L25/22 takes precedence

Abstract

A mobile telecommunication wireless repeater includes: a combination stage for combining a received signal with a feedback cancellation signal; a comparison stage for comparing an input signal of the combination stage with an output signal of the combination stage and determining a weighted value and a time offset value for a feedback signal to be cancelled, based on the comparison; and a recombination stage comprising one or more adaptive filters and configured to receive the weighted value and the time offset value and generate the feedback cancellation signal according to the weighted value and the time offset value.

Claims

1. A mobile telecommunication wireless repeater comprising:

a combination stage for combining a received signal with a feedback cancellation signal;

an adjustable delay for variably delaying an output signal of the combination stage;

a comparison stage for comparing an input signal corresponding to the received signal that is input to the combination stage with the delayed output signal of the combination stage that is delayed by the adjustable delay, and determining and outputting respective weighted values and time offset values for a plurality of feedback signals to be cancelled based on the comparison, wherein first and second ones of the feedback signals are separated by a long time delay interval; and

a recombination stage configured to directly receive the output signal of the combination stage prior to the output signal being delayed by the adjustable delay, and to generate the feedback cancellation signal from the output signal of the combination stage based on the output from the comparison stage, the recombination stage comprising a plurality of paths arranged in parallel, wherein each of the paths comprises a delay function and a corresponding adaptive filter, and wherein each of the delay functions is directly connected to a common first node and each of the adaptive filters is directly connected to a common second node for combining respective output signals of the adaptive filters;

wherein the adaptive filters are configured to receive respective ones of the weighted values and the delay functions are configured to receive respective ones of the time offset values from the comparison stage corresponding to respective ones of the feedback signals, wherein a weight of a filter coefficient of the adaptive filter for each path and the time offset value associated with each path are both independently adjustable based at least on the output from the comparison stage, and wherein the recombination stage is configured to generate the feedback cancellation signal according to the combined output signals from the adaptive filters that correspond to the weighted values and the time offset values for the plurality of the feedback signals.

2. The mobile telecommunication wireless repeater of claim 1, wherein the comparison stage is configured to determine each of the weighted values based on an energy difference between the corresponding feedback signal to be cancelled and the output signal of the combination stage after feedback cancellation, and to provide the weighted values to the recombination stage.

3. The mobile telecommunication wireless repeater of claim 1, wherein when the feedback signals are completely cancelled, the weighted values are adjusted to minimum values.

4. The mobile telecommunication wireless repeater of claim 1, wherein the comparison stage is configured to determine each of the time offset values based on a time difference between the corresponding feedback signal to be cancelled and the output signal of the combination stage after feedback cancellation, and to provide the time offset values to the recombination stage.

5. The mobile telecommunication wireless repeater of claim 1, wherein the recombination stage is configured to determine a final weighted value by adding the weighted values determined by the comparison stage to an existing weighted value, and to apply the final weighted value to the adaptive filters.

6. The mobile telecommunication wireless repeater of claim 1, wherein the recombination stage is configured to apply the time offset values determined by the comparison stage to respective ones of the delay functions corresponding to each of the adaptive filters such that a time offset of the feedback cancellation signal corresponds to a time offset of a feedback signal to be cancelled.

7. The mobile telecommunication wireless repeater of claim 1, wherein each of the paths of the recombination stage is configured to adjust the time offset values of respective ones of the plurality of feedback signals to be cancelled.

8. The mobile telecommunication wireless repeater of claim 7, wherein each of the paths is configured to independently adjust respective ones of the time offset values.

9. The mobile telecommunication wireless repeater of claim 1, further comprising:

a receiving antenna for receiving the received wireless signal;

a down-converter stage for converting the received wireless signal to an intermediate frequency;

an Analog to Digital Converter (ADC) stage for converting the wireless signal of the intermediate frequency to a digital signal;

a Digital to Analog Converter (DAC) stage for converting the output signal of the combination stage to an analog signal of the intermediate frequency; and

an up-converter stage for converting the analog signal of the intermediate frequency to a wireless RF signal and outputting the wireless RF signal to a transmitting antenna.

10. A method of cancelling feedback from a received signal, the method comprising:

combining the received signal with a current feedback cancellation signal;

delaying an output signal after the combination;

comparing an input signal corresponding to the received signal before the combination with the delayed output signal after the combination;

determining and outputting respective weighted values and time offset values for a plurality of feedback signals to be cancelled based on the comparison, wherein first and second ones of the feedback signals are separated by a long time delay interval; and

utilizing a recombination stage to directly receive the output signal after the combination and prior to the output signal being delayed, and to generate a further feedback cancellation signal from the output signal after the combination based on the outputted respective weighted values and time offset values, the recombination stage comprising a plurality of paths arranged in parallel, wherein each of the paths comprises a delay function and a corresponding adaptive filter, wherein each of the delay functions is directly connected to a common first node and each of the adaptive filters is directly connected to a common second node for combining respective output signals of the adaptive filters, wherein the adaptive filters are configured to receive respective ones of the outputted weighted values and the delay functions are configured to receive respective ones of the outputted time offset values corresponding to respective ones of the feedback signals, and wherein a weight of a filter coefficient of the adaptive filter for each path and the time offset value associated with each path are both independently adjustable, to generate a further feedback cancellation signal based on the combined output signals from the adaptive filters that correspond to the weighted values and the time offset values for the plurality of the feedback signals; and

applying the further feedback cancellation signal in place of the current feedback cancellation signal.

11. The method of claim 10, wherein each of the weighted values is determined according to an energy difference between the corresponding feedback signal to be cancelled and the output signal after combination with the current feedback cancellation signal.

12. The method of claim 10, wherein each of the time offset values is determined according to a time difference between the corresponding feedback signal to be cancelled and the output signal after the combination with the current feedback cancellation signal.

13. The method of claim 10, further comprising determining a final weighted value by adding the weighted values to an existing weighted value, and applying the final weighted value to the adaptive filters.

14. The method of claim 10, further comprising applying the time offset values to respective ones of the delay functions corresponding to each of the adaptive filters such that a time offset of the further feedback cancellation signal corresponds to a time offset of a feedback signal to be cancelled.

15. A method of cancelling feedback from a received signal, the method comprising:

combining the received signal with a feedback cancellation signal;

delaying an output signal after the combination;

comparing an input signal corresponding to the received signal before the combination with the delayed output signal after the combination;

determining and outputting a weighted value and a time offset value for each feedback signal of a plurality of feedback signals to be cancelled based on the comparison, wherein first and second ones of the feedback signals are separated by a long time delay interval; and

utilizing a recombination stage to directly receive the output signal after the combination and prior to the output signal being delayed, and to adjust the feedback cancellation signal from the output signal after the combination based on the outputted respective weighted values and time offset values, the recombination stage comprising a plurality of paths arranged in parallel, wherein each of the paths comprises a delay function and a corresponding adaptive filter, and wherein each of the delay functions is directly connected to a common first node and each of the adaptive filters is directly connected to a common second node for combining respective output signals of the adaptive filters;

wherein the adaptive filters are configured to receive respective ones of the outputted weighted values and the delay functions are configured to receive respective ones of the outputted time offset values corresponding to respective ones of the feedback signals, and wherein a weight of a filter coefficient of the adaptive filter for each path and the time offset value associated with each path are both independently adjustable, to adjust the feedback cancellation signal based on the combined output signals from the adaptive filters that correspond to the weighted values and the time offset values for the plurality of the feedback signals.