Haas, Harald

Franke, Bjoern

Tsonev, Dobroslav Antonov

Engineering and Physical Sciences Research Council (EPSRC)

2015-09-11T14:48:52Z

2015-09-11T14:48:52Z

2015-06-29

The growing demand for wireless communication capacity and the overutilisation of the conventional radio frequency (RF) spectrum have inspired research into using alternative spectrum regions for communication. Using optical wireless communications (OWC), for example, offers significant advantages over RF communication in terms of higher bandwidth, lower implementation costs and energy savings. In OWC systems, the information signal has to be real and non-negative. Therefore, modifications to the conventional communication algorithms are required. Multicarrier modulation schemes like orthogonal frequency division multiplexing (OFDM) promise to deliver a more efficient use of the communication capacity through adaptive bit and energy loading techniques. Three OFDM-based schemes – direct-current-biased OFDM (DCO-OFDM), asymmetrically clipped optical OFDM(ACO-OFDM), and pulse-amplitude modulated discrete multitone (PAM-DMT) – have been introduced in the literature. The current work investigates the recently introduced scheme subcarrier-index modulation OFDM as a potential energy-efficient modulation technique with reduced peak-to-average power ratio (PAPR) suitable for applications in OWC. A theoretical model for the analysis of SIM-OFDMin a linear additive white Gaussian noise (AWGN) channel is provided. A closed-form solution for the PAPR in SIM-OFDM is also proposed. Following the work on SIM-OFDM, a novel inherently unipolar modulation scheme, unipolar orthogonal frequency division multiplexing (U-OFDM), is proposed as an alternative to the existing similar schemes: ACO-OFDMand PAM-DMT. Furthermore, an enhanced U-OFDMsignal generation algorithm is introduced which allows the spectral efficiency gap between the inherently unipolar modulation schemes – U-OFDM, ACO-OFDM, PAM-DMT – and the conventionally used DCO-OFDM to be closed. This results in an OFDM-based modulation approach which is electrically and optically more efficient than any other OFDM-based technique proposed so far for intensity modulation and direct detection (IM/DD) communication systems. Non-linear distortion in the optical front-end elements is one of the major limitations for high-speed communication in OWC. This work presents a generalised approach for analysing nonlinear distortion in OFDM-based modulation schemes. The presented technique leads to a closed-form analytical solution for an arbitrary memoryless distortion of the information signal and has been proven to work for the majority of the known unipolar OFDM-based modulation techniques - DCO-OFDM, ACO-OFDM, PAM-DMT and U-OFDM. The high-speed communication capabilities of novel Gallium Nitride based μm-sized light emitting diodes (μLEDs) are investigated, and a record-setting result of 3.5Gb/s using a single 50-μm device is demonstrated. The capabilities of using such devices at practical transmission distances are also investigated, and a 1 Gb/s link using a single device is demonstrated at a distance of up to 10m. Furthermore, a proof-of-concept experiment is realised where a 50-μm LED is successfully modulated using U-OFDM and enhanced U-OFDM to achieve notable energy savings in comparison to DCO-OFDM.

http://hdl.handle.net/1842/10571

en

The University of Edinburgh

D. Tsonev, S. Sinanovic, and H. Haas, “Complete Modeling of Nonlinear Distortion in OFDMbased Optical Wireless Communication,” J. Lightw. Technol., vol. 31, no. 18, pp.3064–3076, Sep. 15, 2013.

D. Tsonev, H. Chun, S. Rajbhandari, J. J. D. McKendry, S. Videv, E. Gu, M. Haji, S. Watson, A. E. Kelly, G. Faulkner, M. D. Dawson, H. Haas and D. OBrien, “A 3-Gb/s Single-LED OFDMbased Wireless VLC Link Using a Gallium Nitride μLED,” IEEE Photon. Technol. Lett., vol. 26, no. 7, pp. 637–640, Apr. 2014.

H. Burchard, N. Serafimovski, D. Tsonev, S. Videv, and H. Haas, “VLC: Beyond Point-to-point Communication,” Comm. Mag., vol. 52, no. 7, pp.98–105, Jul. 2014.

D. Tsonev, S. Sinanovic, and H. Haas, “Enhanced Subcarrier Index Modulation (SIM) OFDM,” in GLOBECOMWorkshops (GC Wkshps), IEEE. Houston, Texas, USA: IEEE, Dec. 5–9, 2011, pp. 728–732.

D. Tsonev, S. Sinanovic, and H. Haas, “Novel Unipolar Orthogonal Frequency Division Multiplexing (U-OFDM) for Optical Wireless,” in Proc. of the Vehicular Technology Conference (VTC Spring), IEEE. Yokohama, Japan: IEEE, May 6–9 2012, pp. 1–5.

D. Tsonev, S. Sinanovic, and H. Haas, “Pulse Shaping in Unipolar OFDM-based Modulation Schemes,” in GLOBECOMWorkshops (GC Wkshps), IEEE, Anaheim, California, USA: IEEE, Dec. 3–7 2012, pp. 1208–1212.

D. Tsonev, S. Sinanovic, and H. Haas, “Practical MIMO Capacity for Indoor Optical Wireless Communication with White LEDs,” in Proc. of the Vehicular Technology Conference (VTC Spring), IEEE, Dresden, Germany: IEEE, Jun. 2–5 2013, pp. 1–5.

D. Tsonev, S. Sinanovic, and H. Haas, “A Novel Analytical Framework for Modeling Nonlinear Distortions in OFDM-based OpticalWireless Communication,” in Proc. of the International Conference on Communications in China (ICCC), IEEE, Xi´an, China: IEEE, Aug. 12–14, pp.147– 152.

D. Tsonev, S. Videv, and H. Haas, “Light Fidelity (Li-Fi): Towards All Optical Networking,” in Proc. of SPIE Photonics West, SPIE, San Francisco, CA, USA: SPIE, Feb. 1–6, pp. 1–10.

D. Tsonev and H. Haas, “Avoiding Spectral Efficiency Loss in Unipolar OFDMfor Optical Wireless Communication,” in Proc. of the International Conference on Communications (ICC). Sydney, Australia: IEEE, Jun., 10–14 2014, pp. 3336–3341.

optial wireless communications

visible light communications

optical modulation

OFDM

High speed energy efficient incoherent optical wireless communications

Thesis or Dissertation

Doctoral

PhD Doctor of Philosophy