Nonlinear least-mean-squares type algorithm for second-order interference cancellation in LTE-A RF transceivers

Abstract

In frequency division duplex transceivers, the limited transmitter-to-receiver duplexer stop-band isolation causes a leakage signal from the transmitter into the receiver. In combination with a finite second-order input intercept point (IIP2), this leads to a second-order intermodulation distortion (IMD2) self-interference in direct conversion architectures which desensitizes the receiver. This IMD2 interference always falls directly into the baseband independent of the frequency offset between transmitter and receiver. In this contribution a nonlinear least-mean-squares type adaptive filter to cancel the transmitter induced IMD2 self-interference is developed which is suitable for highly frequency-selective duplexer stop-bands. The proposed solution outperforms existing adaptive Volterra kernel based algorithms despite its low computational complexity.