US 8,553,610 B2Granted

Interference cancellation repeater incorporating a non-linear element

AssigneeQUALCOMM Incorporated

InventorsKenneth M. Gainey, James A. Proctor, Jr.

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Abstract

A wireless repeater employing echo cancellation uses a non-linear element in digital baseband to compress the digital transmit signal waveform, thereby allowing distortions in the transmitter circuit as well as interference to be cancelled. In one embodiment, the repeater applies non-linear baseband compression to the digital transmit signal in the digital domain to reduce the peak-to-average amplitude of the digital transmit signal prior to digital-to-analog conversion and prior to over-the-air transmission and prior to sampling of the digital transmit signal for use as the reference signal for echo cancellation. The intentionally introduced non-linear distortion in the transmit signal improves echo cancellation and stability of the repeater. In one embodiment, the non-linear compression is applied only when the digital transmit signal is at or exceed a given power level or a given gain level.

Claims20

Dependent claims

A wireless repeater having a first antenna and a second antenna to receive an input signal and transmit an amplified signal, the input signal being a sum of a remote signal to be repeated and a feedback signal resulting from a feedback channel between the first antenna and the second antenna, the repeater comprising:

a first receiver circuit coupled to the first antenna to receive the input signal and to generate a digital input signals at baseband frequency;
a first transmitter circuit coupled to generate the amplified signal to transmit on the second antenna, the amplified signal being generated from a compressed digital transmit signal at baseband frequency;
and
a repeater digital baseband block configured to receive the digital input signal from the first receiver circuit and to generate the compressed digital transmit signal for the first transmitter circuit, the repeater baseband block operative to access a feedback signal estimate, to cancel the feedback signal estimate from the digital input signal to generate an echo cancelled signal, to delay the echo cancelled signal to generate a delayed signal, and to amplify and process the delayed signal to generate a first digital transmit signal, the repeater digital baseband block further configured to apply non-linear baseband compression of the first digital transmit signal to generate the compressed digital transmit signal,
wherein the repeater baseband block is configured to access a feedback signal estimate using the compressed digital transmit signal as a reference signal.

2 more elements

A method in an echo cancellation repeater comprising:

receiving an input signal at a first antenna of the repeater, the input signal being a sum of a remote signal to be repeated and a feedback signal resulting from a feedback channel between the first antenna and a second antenna;
digitizing the input signal to generate a digital input signal at baseband frequency;
cancelling a feedback signal estimate from the digital input signal to generate an echo cancelled signal;
delaying the echo cancelled signal to generate a delayed signal;
amplifying and processing the delayed signal to generate a first digital transmit signal;
applying non-linear baseband compression to the first digital transmit signal to generate a compressed digital transmit signal;
sampling the compressed digital transmit signal as a reference signal to access a feedback channel estimate of the feedback channel;
generating the feedback signal estimate using at least the feedback channel estimate and the reference signal, the feedback signal estimate being used to cancel a feedback signal component of the digital input signal;
generating an amplified signal from the compressed digital transmit signal;
and
transmitting the amplified signal on the second antenna of the repeater.

8 more elements

first means coupled to the first antenna for receiving the input signal and to generate a digital input signals at baseband frequency;
second means for generating the amplified signal to transmit on the second antenna, the amplified signal being generated from a compressed digital transmit signal at baseband frequency;
and
third means for receiving the digital input signal from the first means and generating the compressed digital transmit signal for the second means, the third means for accessing a feedback signal estimate, canceling the feedback signal estimate from the digital input signal to generate an echo cancelled signal, delaying the echo cancelled signal to generate a delayed signal, and amplifying and processing the delayed signal to generate a first digital transmit signal, the third means further for applying non-linear baseband compression of the first digital transmit signal to generate the compressed digital transmit signal,
wherein the third means is configured for accessing a feedback signal estimate using the compressed digital transmit signal as a reference signal.

2 more elements

Dependencies are inferred from the claim text.