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This paper presents a technique for suppressing the intermodulation distortion caused by nonlinear multi-band power amplifiers with minimal modeling complexity. The technique is based on generating a narrowband static predistorter for the power amplifier. Then, the intended multi-band signals are resampled and shifted into their representative carrier frequencies before applying the static predistorter in order to accommodate the intermodulation distortion products produced by the nonlinearity. Since the resampling frequency may be high, a study is presented, using filtering techniques to represent low-bandwidth transmitter schemes, to show the accuracy of the intermodulation distortion suppression. Results are presented for the proposed predistorter for two amplifiers: one in a tri-band carrier aggregated LTE scenario in the sub 3 GHz frequencies and another in the millimeter-wave band, demonstrating the effectiveness of reducing the intermodulation products using 5G signals.

Linearization of user equipment power amplifiers driven by orthogonal frequency division multiplexing signals is addressed in this paper. Particular attention is paid to the power efficient operation of an orthogonal frequency division multiple access cognitive radio system and realization of such a system using compressed sensing. Specifically, precompensated overdriven amplifiers are employed at the mobile terminal. Over-driven amplifiers result in in-band distortions and out of band interference. Out of band interference mostly occupies the spectrum of inactive users, whereas the in-band distortions are mitigated using compressed sensing at the receiver. It is also shown that the performance of the proposed scheme can be further enhanced using multiple measurements of the distortion signal in single-input multi-output systems. Numerical results verify the ability of the proposed setup to improve error vector magnitude, bit error rate, outage capacity and mean squared error.