Orthogonal Vector Approach for Reducing Loadpulling Effect in MIMO Transmitters

In this paper, we propose a low complexity precoding method that is based on orthogonal vector (OV) concept in order to mitigate power amplifier (PA) loadpulling effect in a highly integrated transmitter (Tx) antenna array. The precoder is designed by summing an excitation vector that is orthogonal to the channel state information (CSI) to the conventional zeroforcing (ZF) precoder. In this way the equal constant power (CP) signals can be synthesized and injected into all PAs at each time instant, in the meantime the orthogonality ensures that the additive vector has no impact on the signal at the intended receiver (Rx). The simulations have been performed, and it shows that the proposed precoder can reduce the loadpulling effect with a low complexity algorithm.