SDR-Based All-Optical MIMO Wireless Hybrid IoT Sensor Networks

In this paper, we experimentally demonstrate and analyze the performance of a software-defined radio (SDR)-based all-optical multiple-input multiple-output (MIMO) wireless hybrid communication link for indoor Internet of Things (IoT) sensor networks. We propose an all-optical hybrid scheme using two light-emitting diodes (LEDs) as transmitters (Tx) and photodiode (PD)- and image sensor (IS)-based receivers for simultaneous high- and low-speed data transmission capabilities using visible light communication (VLC) and optical camera communication (OCC) links, respectively. We present a testbed using an SDR platform to transmit and receive high- and low-speed signals and a media converter to introduce them into an optical link. We evaluate the performance of the proposed SDR-based all-optical MIMO wireless hybrid scheme: 1) a single-input multiple-output (SIMO) link employing a single-chip LED for reference, and 2) a MIMO link employing two-chip LEDs modulated with a quadrature phase shift keying signal, in terms of the bit error rate and reception success rate of high-speed VLC and low-speed OCC links, respectively. We show that the proposed scheme can provide independent link performance, irrespective of the significant differences between the operating $R_{b}$ of VLC and OCC. By means of the proposed testbed and measurements, we provide a versatile solution to implement all-optical hybrid links for low-rate IoT environments.