Index modulation multiple access-aided multi-user VLC for Internet of Medical Things

The Internet of Medical Things (IoMT), an extension of the Internet of Things (IoT) focused on healthcare, plays a vital role in enabling continuous monitoring of various medical activities. To address the increasing need for smart medical device connectivity, visible light communication (VLC) has emerged as a promising solution. In this paper, we propose and experimentally demonstrate a multi-user VLC system using an index modulation multiple access (IMMA) scheme tailored for IoMT. By addressing the diverse quality of service (QoS) requirements of different users, the IMMA scheme transmits data for low-speed users via index symbols and for high-speed users via constellation symbols, while significantly reducing the receiver’s computational complexity compared to successive interference cancellation (SIC) in non-orthogonal multiple access (NOMA). The effectiveness of the IMMA scheme has been validated through both simulations and hardware experiments, with bit error rate (BER) performance compared against orthogonal frequency division multiple access (OFDMA) and under varying user separations. Experimental results show that the IMMA scheme outperforms the benchmark schemes and achieves significant distance extensions in a two-user VLC system.