Receiver-side LSBoost-Aided constellation denoising for energy-efficient VLC systems

Abstract

Low-resolution digital-to-analog converters (DACs) have emerged as promising components for visible light communication (VLC) systems, owing to their low power consumption and reduced hardware cost. However, ultra-low-resolution quantization introduces significant signal distortion and limits the achievable modulation formats, particularly in high-speed optical wireless links. In this work, we experimentally demonstrate a receiver-side Least Squares Boosting Constellation Denoiser (LSBCD) designed for asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) VLC systems utilizing low-resolution DACs over a 1-m free-space optical (FSO) link. With standard round-off (RO) quantization, the baseline system supports at most 32-QAM at 4-bit resolution and fails to reach the hard-decision forward error correction (HD-FEC) threshold at 3-bit resolution. While transmitter-side digital resolution enhancer (DRE) techniques can reduce quantization noise and enable higher-order modulation formats (such as 64-QAM at 4-bit), they require additional hardware complexity and transmitter modifications. By contrast, the proposed LSBCD module at the receiver is designed to achieve comparable performance gains with significantly lower computational and implementation complexity. At a symbol rate of 0.75 GBaud, our experimental results show that LSBCD enables reliable 32-QAM transmission using a 3-bit DAC, reducing the bit error rate (BER) from 0.0108 to 0.0033. For 64-QAM with a 4-bit DAC, LSBCD further lowers the BER from 0.0072 to 0.0023, matching or surpassing DRE-based improvements. These findings validate that LSBCD is highly suitable for short-range VLC scenarios. Overall, our research offers a practical and energy-efficient pathway to improve performance in low-resolution OFDM-based VLC systems. The fully receiver-side, modular nature of LSBCD supports flexible integration into future large-scale VLC networks and IoT-oriented optical wireless communication systems, meeting the evolving requirements for cost, scalability, and adaptability in next-generation smart environments.