Low complexity DCO-FBMC visible light communication system

Abstract

Filter Bank Multicarrier (FBMC) is a new waveform candidate in the visible light communication system (VLC). FBMC is a distinctive kind of multi-carrier modulation that can be regarded as an alternative to orthogonal frequency Division Multicarrier (OFDM) with CP (cyclic prefix). DCO-FBMC (DC-bias optical FBMC) has recently been used in VLC, because it overcomes all defects in the optical-OFDM system and has high spectral efficiency. But at the same time the traditional DCO-FBMC suffers from high complexity due to the use of Hermitian Symmetry for real signal, by using 2Npoint subcarrier IFFT (Inverse Fast Fourier Transformer) in the modulator, and the output is N-point subcarrier FFT (Fast Fourier Transform) in the demodulator. In this paper, for the first time, the possibility of minimizing complexity and generating a real signal without the use of Hermitian Symmetry or any other technique has been verified. The proposed technology provides 50% of the size of the IFFT / FFT and this results in a significant reduction in power consumption and occupied chip area.

Enhanced Flip-FBMC visible light communication model

“…Where n is the subcarrier index, m is the time index, ɑ m,n is the massage being transmitted, N is the number of subcarriers; and g(t) is the synthesis function which maps ɑ m,n into the signal space g m,n (t) is the shifted version in time and frequency [14]. After this, the real part is separated from the imaginary part and the imaginary part is converted into real and combined with two consecutively and transmitted, but this real signal is bipolar, so the second condition of the signal is not satisfied, as shown in Figure 1 The time-domain complex signal can be expressed after passing P/S (parallel to serial) as in 2: 1785…”

“…There are several proposed methods for using optical FBMC in VLC systems. Modulation systems must comply with IM/DD [21], [22], meaning that the signal must be real unipolar, so the FBMC modulation system H.S was used to obtain the real signal [23], but this method increases the complexity of IFFT/FFT analysis, where to obtain the number N symbol 2N symbol is used in the frequency field [24], which increases the power consumption, besides that the signal must be unipolar as DC bias is used to convert the bipolar signal to unipolar and this causes power consumption [14], [25]. Modelling the distribution of illumination units in the room is an important factor affecting the distribution of illumination, optical power and SNR [26], [27] The researchers explained many methods of modelling, whether using 4 [28] lighting units or 16 lighting units [29], but these models suffer from low lighting in the middle of the room beside the use of LED with High power consumption and low luminous intensity.…”

Visible light communication using new Flip-FBMC modulation system technique

“…To get a RE sub-carrier, input frequency symbols must be constrained to the IFFT block by using the H.S [25], [27]- [29]. This means that to modulate and demodulate the N frequency symbols, 2N number symbol sub-carriers IFFT/FFT are required to obtain a RE signal with the double of the circuit complexes that meaning 50% loss as shown in Figure 1 as well as in (1) [6], [13], [23], [24], [26], [30], [31]:…”

Three-Layer PAPR Reduction Technique for FBMC Based VLC Systems

“…Recently, visible light communication (VLC) has gained significant attention because it can support high-speed and large-capacity communications compared to traditional wireless radio communications. Also, VLC systems can be used in hospitals, aircraft, and spaceships because they can have a minor impact on electronic devices [1]. Due to their ability to resolve frequency-selective fading impairments at high data rates, multicarrier systems have gotten much attention in recent years.…”