Matrix-based orthogonal polynomials for MIMO transmitter linearization

Abstract

Orthogonal polynomials have been considered as a powerful tool for power amplifier behavioral modeling and Digital Predistortion (DPD) linearization. The application of orthogonal polynomials was limited to SISO systems. This paper extends the idea to MIMO applications and demonstrates the linearization of 2x2 MIMO transmitters in the presence of RF crosstalk using matrix-based orthogonal polynomial linearization architecture. The performance of the proposed DPD has been evaluated using WCDMA and WiMAX standards. By incorporating the proposed DPD linearization topology, the measured ACPR of the WCDMA signal was improved from -42 dBc to -59 dBc and the measured EVM of WiMAX signal was reduced from -25 dB to -52 dB.

New order selection technique using information criteria applied to SISO and MIMO systems predistortion

“…The MMP technique has been developed to accurately model MIMO transmitters. The MMP model considers the effect of RF crosstalk between the two branches of the MIMO transmitter in addition to the transmitter nonlinearities [12, 13].…”

Digital Predistortion for Multi-Antenna Transmitters Affected by Antenna Crosstalk

“…However, nonlinear effects of antenna crosstalk are not considered and cannot be compensated for using these DPD techniques. The crossover DPDs proposed in [12], [13] are designed to compensate for crosstalk before and after the PA. However, in those publications it is assumed that only crosstalk before the PAs is causing nonlinear effects, whereas the effects of crosstalk occurring after the PAs are assumed to be linear.…”