SNR-Based Pre-Emphasis for Transmission of Frequency-Multiplexed Radio Signals in Fronthaul

Abstract

We propose an SNR estimation procedure for systems that transmit frequency-multiplexed analog signals in a channel. It is agnostic to the type of radio signal transmitted, can be performed without increasing the required bandwidth, and without interrupting the transmission of the signals. We simulate the transmission of frequency-multiplexed OFDM signals in an optical channel with intensity modulation of the laser and direct detection, where we show the accuracy of the estimation comparing the estimated SNR to the analytical SNR of the channel. We also evaluate the performance by applying the estimated SNR to derive a pre-emphasis used to transmit the signals. In a first evaluation scenario, the OFDM signals transmitted at higher carrier frequencies without pre-emphasis present lower SNR because of the channel response. In contrast, in a second scenario, all the signals present very close SNR due to the pre-emphasis deployed, which could allow optimizing signal transmission by maximizing the minimum SNR at the channel output.