Analysis of Power De-Rating Represented by Maximum Power Reduction and Cubic Metric in LTE Uplink Transmission

Abstract

Adopted by the uplink transmission for Long Term Evolution (LTE) system, Discrete Fourier Transformation-Spread-Orthogonal Frequency Division Multiplexing (DFT-S-OFDM) can be recognized as a multicarrier technique which is preprocessed by Discrete Fourier Transformation (DFT). Multicarrier signal affected by the nonlinearity of Power Amplifier (PA) brings severe inter-modulation between subcarriers, which causes interference to the adjacent channel and unacceptable Adjacent Channel Leakage power Radio (ACLR). As one of the linearization techniques, power de-rating under a certain level can reduce the adjacent interference efficiently. This paper analyzes the forming of 3rd inter-modulation and the level of power de-rating which can be represented by Maximum Power Reduction (MPR) and Cubic Metric (CM). And also, the factors which influence the value of MPR and CM are discussed based on the analysis of 3rd inter-modulation.