Impact of Liquid Crystal Based Interference Mitigation and Precoding on the Multiuser Performance of VLC Massive MIMO Arrays

In visible light communication systems, the ability to suppress interference caused by other light sources is a major benefit towards performance improvements. Especially for large transmitter arrays or even multi-cell arrangements, the interference problem needs to be handled. In previous work, we...

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Bibliographic Details
Published in:IEEE photonics journal 2022-10, Vol.14 (5), p.1-12
Main Authors: Krohn, Adrian, Harlakin, Andrej, Arms, Steffen, Pachnicke, Stephan, Hoeher, Peter A.
Format: Article
Language:English
Subjects:
Arrays
Communications systems
Free-space optical communication
free-space optics
Interference
interference suppression
LCDs
Light
Light emitting diodes
Light sources
Lighting
liquid crystal display
Liquid crystal displays
MIMO communication
multiple-input multiple-output
Optical communication
optical wireless communication
Optimization
Performance evaluation
Photodetectors
Precoding
Ray tracing
Receivers
Visible light communication
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Summary:In visible light communication systems, the ability to suppress interference caused by other light sources is a major benefit towards performance improvements. Especially for large transmitter arrays or even multi-cell arrangements, the interference problem needs to be handled. In previous work, we have presented a liquid crystal display (LCD) used as an adaptive interference-suppression filter mounted in front of each photodetector. The display elements are switched on and off in such a way that light emitted by unwanted light sources ideally is blocked, but light emitted by desired light sources reaches the detector. The pattern generated by the LC display has strong impact on the system performance. In this paper, we propose combined precoding in conjunction with LCD-based interference suppression in order to increase the signal-to-interference-plus-noise ratio and to ensure user fairness in massive MIMO scenarios. The suggested precoding strategy uses a new heuristic optimization approach based on the Santa Claus problem on unrelated machines known from computer sciences, and employs only binary entries in the weighting matrix. Corresponding results are compared with a genetic evolutionary optimization strategy and with conventional zero-forcing precoding. Regarding performance evaluation, we perform numerical ray-tracing simulations and present a room-scale VLC testbed for experimental verification.
ISSN:1943-0655
1943-0655
1943-0647
DOI:10.1109/JPHOT.2022.3199614