# Slow Beam Steering and NOMA for Indoor Multi-User Visible Light Communications

## TL;DR

This paper introduces a novel approach to slow beam steering combined with NOMA in indoor VLC, optimizing beam directions and power to significantly enhance multi-user data rates.

## Contribution

It proposes a non-convex optimization framework for beam steering and user clustering in VLC, incorporating NOMA to further boost data rates in multi-user scenarios.

## Key findings

- Up to tenfold increase in data rates with power optimization.
- Efficient serving of many users through beam steering and clustering.
- Additional 10 Mbps sum rate gain per NOMA user pair.

## Abstract

Visible light communication (VLC) is an emerging technology that enables broadband data rates using the visible spectrum. In this paper, considering slow beam steering where VLC beam directions are assumed to be fixed during a transmission frame, we find the steering angles that simultaneously serve multiple users within the frame duration and maximize the data rates. This is achieved by solving a non-convex optimization problem using a grid-based search and majorization-minimization (MM) procedure. Subsequently, we consider multiple steerable beams with a larger number of users in the network and propose an algorithm to cluster users and serve each cluster with a separate beam. We optimize the transmit power of each beam to maximize the data rates. Finally, we propose a non-orthogonal multiple access (NOMA) scheme for the beam steering and user clustering scenario, to further increase the data rates of the users. The simulation results show that the proposed beam steering method can efficiently serve a high number of users, and with power optimization, a data rate gain up to ten times is possible. The simulation results for NOMA suggests an additional 10 Mbps sum rate gain for each NOMA user pair.