LMS Adaptive Filter for Digital Cancellation of Second Order Inter-Modulation Due to Transmitter Leakage
First Claim
1. A digital transmit-signal IM2 canceller for a portable handset that operates in a full-duplex mode, the digital transmit-signal canceller, comprising:
- a delay estimator arranged to receive a first input from a receive channel and a second input from a transmit channel of the handset and generates an estimate of the second-order inter-modulation that the transmit channel introduces in the receive channel; and
a digital signal adjuster arranged to receive and remove the estimate of the second-order inter-modulation from the receive channel before forwarding a modified signal to a baseband subsystem of the portable handset.
1 Assignment
0 Petitions
Accused Products
Abstract
A transmit signal second-order inter-modulation (IM2) canceller for a portable handset using a full duplex mode of operation (e.g., WCDMA) is used to controllably reduce IM2 introduced by a transmit signal that appears in a received signal in a receive channel of the portable handset. The transmit signal IM2 canceller includes a delay estimator and a digital signal adjuster. The delay estimator receives a first input from a receive channel and a second input from a transmit channel. The delay estimator generates an estimate of the IM2 that the transmit channel introduces in the receive channel. The digital signal adjuster removes the estimate of the IM2 before forwarding a modified receive channel signal to a baseband subsystem of the portable handset.
37 Citations
20 Claims
-
1. A digital transmit-signal IM2 canceller for a portable handset that operates in a full-duplex mode, the digital transmit-signal canceller, comprising:
-
a delay estimator arranged to receive a first input from a receive channel and a second input from a transmit channel of the handset and generates an estimate of the second-order inter-modulation that the transmit channel introduces in the receive channel; and a digital signal adjuster arranged to receive and remove the estimate of the second-order inter-modulation from the receive channel before forwarding a modified signal to a baseband subsystem of the portable handset. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. A method for cancelling second-order inter-modulation in a mobile handset transceiver, comprising:
-
inserting a canceller between a RF subsystem and a baseband subsystem of the mobile handset; using the canceller to generate an estimate of the second-order inter-modulation expected in a receive channel due to leakage of a transmit signal into the receive channel; and combining a signal from the receive channel with the estimate of the second-order inter-modulation. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
-
Specification