Markov mode-multiplexing mode in OFDM outphasing transmitters

Abstract

Outphasing transmitters have been explored to study the trade-off between linearity and efficiency. The outphasing technique enhances efficiency by operating two amplifiers at lower output amplitudes, using two constant envelope signals. Their major drawback is the inherent sensitivity to gain and phase imbalances between the two amplifier branches. Another important issue is related to the degradation of efficiency, especially in isolated combiners. This paper presents a Statistical Markov-Chain Mode-Multiplexing (MM) transmitter which combines features of the MM and Reverse MM-LINC. Commercial analog devices and a digital platform for signal processing purposes are used to test the performance with an orthogonal frequency multiplexing modulation (OFDM), which is one of the most used modulation schemes in wireless communication systems.