OFDM channel estimation performance under channels with a peak power constraint

OFDM signals suffer significant distortion when transmitted through practical power amplifiers. In this paper, we examine the channel estimation performance of OFDM systems under channels with such a peak power constraint. We consider the effects of null edge subcarriers added for spectral shaping and derive the Crame¿r-Rao bound for channel estimation performance of this system both with pilot power and position optimized for channel estimation, and with uniformly spaced pilots of uniform power. The effects of the peak limitation on both the channel estimation mean-squared error and the overall data symbol mean-squared error are analyzed through simulation. We show that the peak limitation significantly reduces channel estimation performance and demonstrate the existence of an optimal input backoff for channel estimation.