Echo cancellation with transmitter-side pre-filtering
First Claim
1. A method, comprising:
- in a transceiver, receiving from a repeater a received signal, which comprises a desired signal for reception and an undesired replica of a transmitted signal that was transmitted from the transceiver and retransmitted by the repeater;
generating in the transceiver a local copy of the transmitted signal;
estimating in the transceiver a filter response that, when applied to the transmitted signal before transmission, compensates for a difference in spectral response between (i) the local copy of the transmitted signal and (ii) the undesired replica of the transmitted signal, wherein estimating the filter response comprises estimating frequency-dependent variations in phase and gain between the local copy of the transmitted signal and the undesired replica of the transmitted signal, across a given bandwidth;
matching the undesired replica of the transmitted signal, which is received in the received signal, with the local copy of the transmitted signal, by at least pre-filtering the transmitted signal before transmission with the estimated filter response; and
canceling an interference caused by the undesired replica to the desired signal, by combining the local copy and the received signal.
1 Assignment
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Accused Products
Abstract
A method includes, in a transceiver (24), receiving from a repeater (32) a received signal, which includes a desired signal for reception and an undesired replica of a transmitted signal that was transmitted from the transceiver and retransmitted by the repeater. A local copy of the transmitted signal is generated in the transceiver. A filter response that, when applied to the transmitted signal before transmission, compensates for a difference in spectral response between the local copy and the undesired replica, is estimated in the transceiver. The undesired replica of the transmitted signal, which is received in the received signal, is matched with the local copy of the transmitted signal, by at least pre-filtering the transmitted signal before transmission with the estimated filter response. Interference caused by the undesired replica to the desired signal is canceled, by combining the local copy and the received signal.
59 Citations
18 Claims
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1. A method, comprising:
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in a transceiver, receiving from a repeater a received signal, which comprises a desired signal for reception and an undesired replica of a transmitted signal that was transmitted from the transceiver and retransmitted by the repeater; generating in the transceiver a local copy of the transmitted signal; estimating in the transceiver a filter response that, when applied to the transmitted signal before transmission, compensates for a difference in spectral response between (i) the local copy of the transmitted signal and (ii) the undesired replica of the transmitted signal, wherein estimating the filter response comprises estimating frequency-dependent variations in phase and gain between the local copy of the transmitted signal and the undesired replica of the transmitted signal, across a given bandwidth; matching the undesired replica of the transmitted signal, which is received in the received signal, with the local copy of the transmitted signal, by at least pre-filtering the transmitted signal before transmission with the estimated filter response; and canceling an interference caused by the undesired replica to the desired signal, by combining the local copy and the received signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A communication transceiver, comprising:
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a front end, which is configured to exchange signals with a repeater; and a modem, which is configured to; receive from the repeater a received signal, which comprises a desired signal for reception and an undesired replica of a transmitted signal that was transmitted from the transceiver and retransmitted by the repeater; generate a local copy of the transmitted signal; estimate a filter response that, when applied to the transmitted signal before transmission, compensates for a difference in spectral response between (i) the local copy of the transmitted signal and (ii) the undesired replica of the transmitted signal, by estimating frequency-dependent variations in phase and gain between the local copy of the transmitted signal and the undesired replica of the transmitted signal, across a given bandwidth; match the undesired replica of the transmitted signal, which is received in the received signal, with the local copy of the transmitted signal, by at least pre-filtering the transmitted signal before transmission with the estimated filter response; and cancel an interference caused by the undesired replica to the desired signal, by combining the local copy and the received signal. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification