Adaptive Real-Time Software Defined MIMO Visible Light Communications using Spatial Multiplexing and Spatial Diversity

TL;DR

This paper demonstrates an adaptive real-time MIMO VLC system using FPGA-based software-defined link adaptation of spatial multiplexing and diversity, improving error performance and spectral efficiency in dynamic indoor environments.

Contribution

It introduces a reconfigurable, software-defined MIMO VLC system with adaptive modulation and MIMO schemes implemented on FPGA, enabling dynamic optimization based on channel conditions.

Findings

Adaptive 2x2 MIMO VLC achieved 12 b/s/Hz spectral efficiency.

Spatial diversity improves error performance, spatial multiplexing enhances spectral efficiency.

Real-time FPGA implementation enables flexible MIMO VLC system.

Abstract

In this paper, we experimentally demonstrate a real-time software defined multiple input multiple output (MIMO) visible light communication (VLC) system employing link adaptation of spatial multiplexing and spatial diversity. Real-time MIMO signal processing is implemented by using the Field Programmable Gate Array (FPGA) based Universal Software Radio Peripheral (USRP) devices. Software defined implantation of MIMO VLC can assist in enabling an adaptive and reconfigurable communication system without hardware changes. We measured the error vector magnitude (EVM), bit error rate (BER) and spectral efficiency performance for single carrier M-QAM MIMO VLC using spatial diversity and spatial multiplexing. Results show that spatial diversity MIMO VLC improves error performance at the cost of spectral efficiency that spatial multiplexing should enhance. We propose the adaptive MIMO solution that both modulation schema and MIMO schema are dynamically adapted to the changing channel conditions for enhancing the error performance and spectral efficiency. The average error-free spectral efficiency of adaptive 2x2 MIMO VLC achieved 12 b/s/Hz over 2 meters indoor dynamic transmission.