Wideband echo cancellation in a repeater

A wireless repeater having a first antenna and a second antenna for receiving an input signal and transmitting 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:

• first means for receiving the input signal and providing receive and transmit front-end processing;
• second means for providing receive and transmit front-end processing and generating the amplified signal
• means for receiving a processed input signal from the first front-end circuit and generating an output signal to be processed by the second front-end circuit, the means comprising:
• means for receiving the processed input signal and estimating the feedback channel to provide a feedback channel estimate using frequency domain channel estimation;
• means for generating a feedback signal estimate based on the feedback channel estimate and cancelling the feedback signal estimate from the input signal using time domain echo cancellation;
• means for amplifying the echo cancelled signal to generate the output signal of the repeater baseband block, the gain of the variable gain stage being adjusted by a means for controlling gain means implementing digital gain control to maintain repeater stability;
• means for introducing a first delay before or after the echo canceller and providing a delayed echo cancelled signal to the means for amplifying the echo cancelled signal, the first delay being selected to provide decorrelation of the remote signal with the amplified signal, the first delay less than a maximum decorrelation delay amount;
• and
• means for introducing a second delay to the output signal, the second delay being selected to reduce delay spread, the delayed output signal being coupled to the means for estimating the feedback channel as a reference signal for estimating the feedback channel, to the means for generating the feedback signal estimate, and to the means for controlling gain for monitoring the stability of the repeater.

A method for providing wideband echo cancellation in a wireless repeater in a wireless communication system, 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;
• performing front-end processing on the input signal;
• estimating a feedback channel between the first antenna and the second antenna of the repeater using frequency domain channel estimation;
• generating a feedback signal estimate based on the feedback channel estimate;
• cancelling the feedback signal estimate from the input signal and generating an echo cancelled signal using time domain echo cancellation;
• determining a gain value for maintaining repeater stability using digital gain control;
• amplifying the echo cancelled signal using the gain value to generate an output signal;
• introducing a first delay to the signal before or after cancelling the feedback signal estimate and providing a delayed echo cancelled signal, the first delay being selected to provide decorrelation of the remote signal with the amplified signal, the first delay less than a maximum decorrelation delay amount;
• introducing a second delay to the output signal, the second delay being selected to reduce delay spread;
• providing the delayed output signal as a reference signal for estimating the feedback channel, for generating the feedback signal estimate, and for determining a gain value;
• performing front-end processing on the output signal to generate the amplified signal;
• and
• transmitting the amplified signal on the second antenna.