The performance and efficiency of envelope elimination and restoration transmitters for future multiple-input multiple-output wireless local area networks

The inefficiency of contemporary power amplifiers (PAs), when operating in their linear region, is a major obstacle to mobile operation of wireless local area networks (WLANs) based on IEEE 802.11n. Therefore the use of more efficient envelope elimination and restoration (EER) transmitter architectures is considered. In addition to high efficiency it is also necessary to satisfy the spectral mask and achieve satisfactory link-level performance. Link-level simulations of a contemporary WLAN PA show that, at the power back-offs necessary to achieve sufficient linearity, the power added efficiency (PAE) is only ~1% for a system with four transmit antennas. In contrast, simulations of a phase feedback EER PA architecture show that it is possible to achieve an average PAE of 70%, while satisfying the spectral mask, with only a small degradation in link-level performance.