On the Out-of-Band Radiation Reduction in OFDM Systems

In this paper, we consider the problem of high out-of-band (OOB) radiation in OFDM systems. OOB radiation is mainly caused by high peak-to-average power ratio (PAPR) of OFDM signal that drives high power amplifier (HPA) in nonlinear region. We investigate the OOB reduction capabilities of the most common PAPR reduction algorithms and compare their performance. We determine input back-off of HPA needed to achieve adjacent channel leakage ratio (ACLR) requirement assuming different PAPR reduction algorithms, HPA characteristics and modulation schemes. Also, we consider the factors that contribute to OOB in OFDM and show how to distinguish them.