DCO-OFDM Channel Sounding with a SiPM Receiver

Presented at the 2021 IEEE Photonics Conference. OFDM assumes a linear channel and SiPMs are not linear, so this paper tests whether the two can work together.

Abstract

Orthogonal Frequency-Division Multiplexing (OFDM) is a popular modulation scheme, which requires a linear channel. Unfortunately, the most sensitive receivers for visible light communications, silicon photomultipliers (SiPMs), have a non-linear response. Despite this incompatibility, results from an easily implemented method of combining OFDM and SiPMs are shown to successfully limit the bit error rate to below the limit required by forward error correction.

Key Findings

SiPMs detect individual photons, but the way they do it makes their response non-linear in the light intensity. That matters for OFDM, which assumes a linear channel. Conventional methods of loading OFDM sub-carriers fail at lower light intensities because of this non-linearity. A new loading method works, and reaches 453 Mbps. The highest OFDM data rate previously reported with a SiPM was 20 Mbps.