Effcient Techniques for High-Speed Visible Light Communication Systems

  • Hanaa Marshoud

Student thesis: Doctoral Thesis

Abstract

Hanaa Marshoud, 'Efficient Techniques for High-Speed Visible Light Communica- tion Systems', PhD. Thesis, PhD in Engineering, Department of Electrical and Computer Engineering, Khalifa University of Science and Technology, United Arab Emirates, July 2017. The increasing demand of high data rate services and the emergence of the Internet of Things pose unique challenges for the next generation wireless communications, including, but not limited to, high energy and spectral efficiency and massive connectivity. Visible light communication (VLC) has recently emerged as a promising solution for indoor ubiquitous broadband connectivity. The main challenges of VLC systems, however, are the low modulation bandwidth of the light-emitting-diodes and the stringent requirements of VLC-based intensity modulation and direct detection (IM/DD), which require signals to be real and unipolar. In this research, we propose three different solutions for high data-rate indoor VLC-downlink networks. In our first contribution, we propose non-orthogonal multiple access (NOMA) as a promising scheme to enhance the achievable throughput in VLC systems. To this end, we develop a comprehensive framework for the design and analysis of indoor NOMA-VLC multi-LED downlink networks. The second contribution of this research is the proposal of a novel optical asymmetric modulation (OAM) scheme that is designed to enable high-order transmissions within the restrictions of IM/DD. The idea of OAM is based on representing each constellation symbol as the sum of the sine and cosine of predetermined angles. The performance of the proposed scheme is analyzed and compared to other modulation schemes that are typically used for high-rate VLC systems. Finally, in our third contribution, we investigate the performance of multiple-input-multiple-output (MIMO) based VLC systems, where inter-channel interference (ICI) is mitigated by means of transmit precoding. In this regard, we compare the performance of different precoding schemes under channel estimation errors, an assumption that is commonly neglected in the literature. Moreover, we propose a novel optical adaptive precoding (OAP) scheme which exploits the constructive ICI among the MIMO subchannels to enhance the system performance.
Date of AwardJul 2017
Original languageAmerican English
SupervisorSami Muhaidat (Supervisor)

Keywords

  • Visible light communication
  • non-orthogonal multiple access
  • intensity modulation
  • multiple-input-multiple-output
  • precoding
  • error rate analysis.

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