Improved Performance in the Detection of ACO-OFDM Modulated Signals Using Deep Learning Modules

Abstract

Free space optical communication (FSO) is widely deployed to transmit high data rates for rapid communication traffic increase. Asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) modulation is a very efficient FSO communication technique in terms of transmitted optical power. However, its performance is limited by atmospheric turbulence. When the channel includes strong turbulence or is non-deterministic, the bit error rate (BER) increases. To reach optimal performance, the ACO-OFDM decoder needs to know accurate channel state information (CSI). We propose novel detection using different deep learning (DL) algorithms. Our DL models are compared with minimum mean square error (MMSE) detection methods in different turbulent channels and improve performance especially for non-stationary and non-deterministic channels. Our models yield performance very close to that of the MMSE estimator when the channel is characterized by weak or strong turbulence and is stationary. However, when the channel is non-stationary and variable, our DL model succeeds in improving the performance of the system and decreasing the signal to noise ratio (SNR) by more than 8 dB compared to that of the MMSE estimator, and it succeeds in recovering the received data without needing to know accurate CSI. Our DL decoders also show notable speed and energy efficiency improvement.

Investigations on Orthogonal-Frequency Division Multiplexed-Mode-Division Multiplexed MM Wave-on-Free Space Optics Transmission using Laguerre-Gaussian Modal Beams

“…Panda and Bhanja (2021) reported an improved performance evaluation of OFDM-FSO scheme by designing a modified OFDM receiver. In the previous works reported in (Sharma, 2014;Patel et al, 2014;Nistazakis et al, 2016;Attri et al, 2017;Zhang et al, 2018;Ajewole et al, 2019;Gupta et al, 2019;Hario et al, 2019;Darwesh and Kopeika, 2020;Panda and Bhanja, 2021) single-channel OFDM transmission has been discussed over free-space channel. Further enhancement of transmission capacity of FSO can be achieved by employing more OFDM channels transmission simultaneously which can be achieved using Wavelength-Division Multiplexed (WDM) transmission.…”

“…The authors reported faithful 10 Gbps-2 km transmission for sunny climate with favourable SNR at the demodulator. Darwesh and Kopeika (2020) reported the improvement in the detection mechanism of asymmetrical clipped optical-OFDM signals in a FSO scheme by employing deep learning techniques. Panda and Bhanja (2021) reported an improved performance evaluation of OFDM-FSO scheme by designing a modified OFDM receiver.…”

Hybrid PAPR reduction schemes for different OFDM-based VLC systems

“…DCO-OFDM is considered as one of the simplest and earliest MCM techniques to be compatible with IM/DD systems by generating a real and non-negative-valued OFDM scheme. It involves adding DC-bias to the signal which is supposed to be in unipolar format [9,10]. The block diagram of DCO-OFDM is shown in Fig.…”

Integrating Wireless Sensor Network with Li-Fi Wireless Communication Technology based on NOMA Technique: A Survey

“…Unevenly Clipped Optical Orthogonal Frequency Division Multiplexing (ACO-OFDM) modulation is one of the strategies that can change over the transmitted signals to be bipolar and genuine without any loss of the transmission data [40]. It is proficient in terms of optical power for lower SNR values for the IM/DD channel [41].…”