Single carrier optical FDM in visible light communication

Abstract

Abstract-Light emitting diodes (LEDs) used in visible light communications (VLC) have a limited optical power-current linear range, which could be a problem in multi-level and multicarrier frequency modulation schemes. Orthogonal frequency division multiplexing (OFDM) as a popular scheme in VLC suffers from nonlinear distortion due to the high peak to average power ratio (PAPR). In this paper, we present a novel single carrier optical frequency division multiplexing signaling scheme for VLC, where the symmetrical characteristics of single carrier frequency division multiple access is investigated in order to reduce PAPR. Simulation results show that PAPR reduced by 10 dB compared to the traditional asymmetrically clipped optical OFDM. We show that the bit-error-rate performance of the proposed scheme is enhanced compared to ACO-OFDM when the limited dynamic range of digital to analog converter and LED is considered.

Unipolar-pulse amplitude modulation frequency division multiplexing for visible light communication systems

“…In [25], it was demonstrated that, because of HS only half of the ACO-SCFDE samples would have a single carrier PAPR behavior, while the other half will have the same PAPR as in OFDM. However, in our recent work [28,29], we showed that PAPR of optical IFDMA can be improved by not considering HS requirement and therefore making it to be as low as the PAPR of IFDMA in the RF domain. This was achieved in [29] by symmetrically repeating the IFDMA time domain symbol twice by means of setting the interleaving factor (Q) in the frequency domain to be 2.…”

Optical single carrier-interleaved frequency division multiplexing for visible light communication systems

“…In our recent work [15], the PAPR of an optical OFDM signal was significantly reduced for IM/DD based VLC systems by employing SC-IFDMA with no HS. This was achieved by repeating the SC-IFDMA time domain symbol symmetrically four times through setting the interleaving factor (Q) in the frequency domain to four.…”

“…As such, the SC-IFDMA symbol is transmitted using the 1 st , 2 nd , 3 rd and 4 th sub-symbols, which represent positive values of the real and imaginary samples, and negative values of real and imaginary samples, respectively. However, the 1 st subcarrier (DC-bias) in [15] was none-zero (i.e., modulated subcarrier), which can affect all time domain samples and consequently increase the BER. Note that, the DC-bias is a requirement in VLC systems for illumination and to remove the effect of the pulse shaping filter, which can convert unipolar signals into a bipolar format [1,2,16].…”

“…Note that, the DC-bias is a requirement in VLC systems for illumination and to remove the effect of the pulse shaping filter, which can convert unipolar signals into a bipolar format [1,2,16]. In order to improve the performance of our aforementioned work in [15], we have introduced a dedicated algorithm to reduce the effect of the DC-bias, but at the cost of increased SNR compared to the traditional DCO-OFDM. Furthermore, we show that, the spectral efficiency is doubled by reducing Q by a factor of 2 compared to the previous work [15].…”

“…In order to improve the performance of our aforementioned work in [15], we have introduced a dedicated algorithm to reduce the effect of the DC-bias, but at the cost of increased SNR compared to the traditional DCO-OFDM. Furthermore, we show that, the spectral efficiency is doubled by reducing Q by a factor of 2 compared to the previous work [15].…”