Enhancing the Sum Rate in Massive MIMO Optical Wireless Communication System by Using MMSE Precoding

We investigate an optical wireless communications system based on massive multiple-input multiple-output (MIMO). Through a transmit lens, the optical base station with its huge optical transmitters communicates with the user terminals (UTs). We create a channel model for optical massive MIMO transmissions and examine light refraction caused by lenses, with an emphasis on LED transmitters. We formulate the sum rate maximization problem and convert it into a convex optimization problem to get a closed-form solution. MMSE is used to increase the sum rate and Karush-Kuhn-Tucker (KKT) conditions were used to solve the aforementioned problem. We study traditional precoding techniques, maximum ratio transmission (MRT), and regularized zero-forcing precoding (RZF) for an optical massive MIMO system. The proposed technique is ajoint precoder design to enhance the sum rate. The simulation results show that the proposed MMSE precoder design outperforms MRT and RZF precoders in a massive MIMO optical wireless communication system.