|ชื่อเรื่อง||:||Analysis of OFDM-based intensity modulation techniques for optical wireless communications|
|นักวิจัย||:||Dimitrov, Svilen Dimitrov|
|คำค้น||:||Optical wireless communication , OFDM , non-linear distortion , information rate|
|หน่วยงาน||:||Edinburgh Research Archive, United Kingdom|
|ผู้ร่วมงาน||:||Haas, Harald , Thompson, John|
|ความสัมพันธ์||:||S. Dimitrov, S. Sinanovic, and H. Haas, Clipping Noise in OFDM-based OpticalWireless Communication Systems, IEEE Transactions on Communications (IEEE TCOM), vol. 60, pp. 1072- 1081, Apr. 2012. , S. Dimitrov, S. Sinanovic, and H. Haas, Signal Shaping and Modulation for Optical Wireless Communication, IEEE/OSA Journal on Lightwave Technology (IEEE/OSA JLT), vol. 30, pp. 1319-1328, May 2012. , S. Dimitrov and H. Haas, On the Clipping Noise in an ACO-OFDM Optical Wireless Communication System, in Proc. of IEEE Global Communications Conference (IEEE GLOBECOM 2010), Miami, Florida, USA, 6-10 Dec. 2010 , S. Dimitrov, H. Haas, M. Cappitelli, and M. Olbert, On the Throughput of an OFDM-based Cellular Optical Wireless System for an Aircraft Cabin, in Proc. of European Conference on Antennas and Propagation (EuCAP 2011), Rome, Italy, 11-15 Apr. 2011. Invited Paper. , S. Dimitrov, S. Sinanovic, and H. Haas, Double-sided Signal Clipping in ACO-OFDM Wireless Communication Systems, in Proc. of IEEE International Conference on Communications (IEEE ICC 2011), Kyoto, Japan, 5-9 June 2011 , S. Dimitrov, S. Sinanovic, and H. Haas, A Comparison of OFDM-based Modulation Schemes for OWC with Clipping Distortion, in Proc. of the 2nd Optical Wireless Communications (OWC) Workshop in conjunction with IEEE Global Telecommunications Conference (IEEE GLOBECOM 2011), Houston, Texas, USA, 5-9 Dec. 2011. , S. Dimitrov and H. Haas, Optimum Signal Shaping in OFDM-based Optical Wireless Communication Systems, in Proc. of the IEEE Vehicular Technology Conference (IEEE VTC Fall), Quebec City, Canada, Sept. 3-6 2012.|
Optical wireless communication (OWC) is a promising alternative to radio frequency (RF) communication with a significantly larger and unregulated spectrum. Impairments in the physical layer, such as the non-linear transfer characteristic of the transmitter, the dispersive optical wireless channel and the additive white Gaussian noise (AWGN) at the receiver, reduce the capacity of the OWC system. Single-carrier multi-level pulse position modulation (M-PPM) and multilevel pulse amplitude modulation (M-PAM) suffer from inter-symbol interference (ISI) in the dispersive channel which reduces their capacity even after channel equalization. Multi-carrier modulation such as optical orthogonal frequency division multiplexing (O-OFDM) with multilevel quadrature amplitude modulation (M-QAM) is known to maximize the channel capacity through bit and power loading. There are two general signal structures: bipolar Gaussian signal with a direct current (DC) bias, i.e. DC-biased O-OFDM (DCO-OFDM), or unipolar half- Gaussian signal, employing only the odd subcarriers, i.e. asymmetrically clipped O-OFDM (ACO-OFDM). In this thesis, the signal distortion from the transmitter nonlinearity is minimized through pre-distortion, optimum signal scaling and DC-biasing. The optical front-ends impose minimum, average and maximum optical power constraints, as well as an average electrical power constraint, on the information-carrying signals. In this thesis, the optical signals are conditioned within these constraints through optimum signal scaling and DC-biasing. The presented analysis of the optical-to-electrical (O/E) conversion enables the derivation of the electrical signal-to-noise ratio (SNR) at the receiver, including or excluding the additional DC bias power, which is translated into bit-error rate (BER) performance. In addition, a generalized piecewise polynomial model for the non-linear transfer characteristic of the transmitter is proposed. The non-linear distortion in O-OFDM is translated by means of the Bussgang theorem and the central limit theorem (CLT) into attenuation of the data-carrying subcarriers at the receiver plus zero-mean complex-valued Gaussian noise. The attenuation factor and the variance of the non-linear distortion noise are derived in closed form, and they are accounted towards the received electrical SNR. Through pre-distortion with the inverse of the proposed piecewise polynomial function, the linear dynamic range of the transmitter is maximized, reducing the non-linear distortion to double-sided signal clipping. Finally, the OWC schemes are compared in terms of spectral efficiency and electrical SNR requirement as the signal bandwidth exceeds the coherence bandwidth of the optical wireless channel for a practical 10 dB linear dynamic range. Through optimum signal scaling and DCbiasing, DCO-OFDM is found to achieve the highest spectral efficiency for a target SNR, neglecting the additional DC bias power. When the DC bias power is counted towards the signal power, DCO-OFDM outperforms PAM with linear equalization, approaching the performance of the more computationally intensive PAM with non-linear equalization. In addition, the average optical power in O-OFDM is varied over dynamic ranges of 10 dB, 20 dB and 30 dB. When the additional DC bias power is neglected, DCO-OFDM is shown to achieve the Shannon capacity, while ACO-OFDM exhibits a 3 dB gap which grows with higher SNR targets. When the DC bias power is included, DCO-OFDM outperforms ACO-OFDM for the majority of average optical power levels with the increase of the SNR target or the dynamic range.
Dimitrov, Svilen Dimitrov . (2556). Analysis of OFDM-based intensity modulation techniques for optical wireless communications.
กรุงเทพมหานคร : Edinburgh Research Archive, United Kingdom .
Dimitrov, Svilen Dimitrov . 2556. "Analysis of OFDM-based intensity modulation techniques for optical wireless communications".
กรุงเทพมหานคร : Edinburgh Research Archive, United Kingdom .
Dimitrov, Svilen Dimitrov . "Analysis of OFDM-based intensity modulation techniques for optical wireless communications."
กรุงเทพมหานคร : Edinburgh Research Archive, United Kingdom , 2556. Print.
Dimitrov, Svilen Dimitrov . Analysis of OFDM-based intensity modulation techniques for optical wireless communications. กรุงเทพมหานคร : Edinburgh Research Archive, United Kingdom ; 2556.