Broadband Optical Wireless Communications

Open Access
Author:
Zhou, Zhou
Graduate Program:
Electrical Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
August 30, 2013
Committee Members:
  • Mohsen Kavehrad, Dissertation Advisor
  • Mohsen Kavehrad, Committee Chair
  • Iam Choon Khoo, Committee Member
  • John Metzner, Committee Member
  • Sencun Zhu, Committee Member
Keywords:
  • Optical wireless communications
  • Power-line communications
  • Aircraft wireless network
  • indoor navigation
  • LED
  • OFDM
  • MIMO
Abstract:
As Light-Emitting Diode (LED)’s increasingly displace incandescent lighting over the next few years, general applications of Indoor Optical Wireless Communications (IOWC) technology are expected to include wireless internet access, broadcast from LED signage, and machine-to-machine communications. This dissertation explores several fundamental research topics of IOWC. In this dissertation, the author develops a simulation method to generate IOWC channel models by tracking light reflections. The method is further optimized by investigating the contribution of each order of reflections and proposing a calibration method. Based on the channel models, the author reveals that sources’ Half-Power Angles (HPA), receivers’ Field-Of Views (FOV), sources layout, and the power distribution among sources are the significant factors impacting IOWC system quality. The dissertation also investigates the applications of advanced communication techniques to improve IOWC performance. The author starts by performing bit-error rate (BER) distributions and outage probability estimations using intensity modulation / direct detection (IM/DD) with additive white Gaussian noise (AWGN). Next, various orthogonal frequency-division multiplexing (OFDM) schemes are applied to mitigate the multipath effect in IOWC and decrease clipping noise. Precoding approaches are also used to reduce peak-to-average power ratio (PAPR) in OFDM systems. In addition, the multiple-input and multiple-output (MIMO) methods are explored to increase system reliability and/or band efficiency. Finally, this dissertation extends its topics to specific industrial applications of IOWC. By customizing the channel simulation for airplane cabins, the visible light propagation features in this environment are investigated. The results confirmed the effectiveness of applying IOWC to airplane cabin wireless communications. An efficient algorithm to apply IOWC to indoor navigations is also developed.