A Symbol Rate Adaptation Method for Ultraviolet Communication Systems

Abstract

To enable reliable and efficient communication under time-varying channel conditions, this paper proposes a feedback-based symbol rate adaptation scheme for ultraviolet (UV) communication. The receiver periodically reports channel state information, including the mean detected photon counts of signal and background components, to the transmitter after a fixed number of frames. Based on this feedback and predefined rate-switching thresholds obtained from off-line low-density parity-check (LDPC) performance simulations, the receiver selects appropriate symbol rates from a set of discrete levels and conveys the update decisions through a feedback channel. A lightweight decision logic is adopted to enable timely rate adjustments, and a feedback frame structure with frame indices is designed to ensure reliable symbol rate synchronization under frame loss. Indoor experiments with controlled link distance and noise variations verify the predictable adaptation behavior of the proposed scheme, while outdoor daylight experiments demonstrate stable communication and effective symbol rate tracking under time-varying channel conditions.