R. Maslennikov

Comparison of Power Amplifier Non-Linearity Impact on 60 GHz Single Carrier and OFDM Systems

This paper presents a detailed analysis of the impact of power amplifier (PA) non-linearity on the performance of single carrier (SC) and OFDM systems in 60 GHz spectrum. The efficiency of the considered systems was analyzed by estimating values of the power amplifier output backoff needed to meet the requirements on the transmit spectrum mask (TSM) compliance and error vector magnitude (EVM). Different models of the PA including an experimentally measured model for the 60 GHz PA were considered. It was estimated that for many types of modulations and PA models, SC system can have up to 1.5 dB higher output power than OFDM system. However, for the experimental PA model accounting for amplitude modulation-phase modulation distortion in addition to amplitude modulation - amplitude modulation distortion, the difference between the OFDM and SC output power levels was minimal, and OFDM even had approximately 1 dB better performance than SC for the BPSK modulation. A potential improvement in the transmit power due to application of digital predistortion techniques was estimated for both systems to be in the range from 1.5 to 3.4 dB.

Comparative analysis of influence of non-linear distortion in power amplifier in wireless communications systems with single and multiple orthogonal carrier frequencies

The paper considers the impact of power amplifier’s non-linearity on wireless communication systems with a single carrier (SC) and multiple orthogonal subcarriers (OFDM). Detailed analysis is provided for the impact of non-linearity on generation accuracy of the transmitted signal and the shape of the output spectrum. It is demonstrated that in order to meet standard requirements to the signal generation accuracy and the spectrum mask compliance, a SC system typically has a moderate gain of 1–1.5 dB in comparison with an OFDM system. It is concluded that a decision on the modulation type selection for a wireless communication system should include additional factors beyond the power amplifier non-linearity impact analysis.