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 Rb 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.