Millimeter-wave enabled PAM-4 data transmission over hybrid FSO-MMPOF link for access networks

Abstract

In this paper, we propose a full duplex architecture based on a hybrid link composed of free space optics (FSO) and multimode plastic optical fiber (MMPOF) for short-range wireless access networks. The proposed architecture employs mode group division multiplexing (MGDM) and wavelength reuse techniques to transmit data between central unit (CU) and radio access units (RAUs). An optical frequency comb source to generate multiple optical sidebands is realized using a single laser source to provide 60 GHz millimeter-wave (mm-wave) signals at each RAU by simultaneously transmitting PAM-4 signal on linearly polarized (LP) modes of each optical sideband. Data rate of 2$$\times$$ × 12 Gbps at mm-wave frequency of 60 GHz is achieved for both downlink (DL) and uplink (UL) transmissions. The transmission of 2$$\times$$ × 12 Gbps PAM-4 signal over hybrid FSO-MMPOF link is investigated at different values of refractive index structure parameter ($$C_n^2$$ C n 2 ) by employing log-normal (LN) FSO channel model to support three RAUs in a ring topology. The acceptable receiver sensitivities below −5 and −0.6 dBm for DL and UL transmissions are achieved, respectively. The proposed hybrid architecture can be a potential candidate for future communication networks.

An integrated design for improving spectral efficiency of FSO communication system in 6G applications

“…Due to the lack of licensed spectrum resources, serious problems arise that cannot be determined by the prevailing RF communication systems 9 . Although the RF spectrum is readily available for mobile access networks, satisfying the 6G target data rate is extremely complex due to the lower bandwidth 10 . To overcome these problems, an emerging FSO acts as an effective system for future wireless networks in terms of royalty‐free features and high capacity.…”

Semiconductor Optical Amplifier (SOA)-Driven Reservoir Computing for Dense Wavelength-Division Multiplexing (DWDM) Signal Compensation

“…Intelligent signal processing through an artificial neural network (ANN) is a powerful tool for performing signal compensation functions and has been used to mitigate distortions from both linear and nonlinear effects [ 9 , 10 , 11 ]. Although a conventional off-line DSP scheme, such as a feed-forward equalizer (FFE), could perform a similar function on the data compensation [ 12 , 13 ], ANN-based OSP has advantages in terms of its low complexity and high robustness, enabling it to deal with the distorted signals from different scenarios. Reservoir computing (RC) is one of the ANN-based computing techniques that has been intensively investigated recently because of the potential hardware implementation with low complexity [ 14 , 15 , 16 , 17 , 18 ].…”

Mode division multiplexing free space optics system with 3D hybrid modulation under dust and fog

“…As conventional modulation formats are limited to below 40 Gbps, it is of utmost importance to propose a modulation technique to enhance the capacity per channel. Recently, various modulation techniques have been discussed to augment the capacity of single-channel wireless systems [1][2][3][4]. But, the hybrid multi-dimensional modulation technique shows better results as it not only increases the speed of the channel but also increases the number of users [1].…”

“…Using hybrid modulation for more than one user can transmit data into a single channel using different parameters of a common signal. Several new modulation schemes, for instance: amplitude shift keying (ASK), frequency-shift keying (FSK), differential phase-shift keying (DPSK), and combined signaling like ASK-DPSK and DPSK-dark return-to-zero (DPSK-DRZ) have invited ample interest because of high spectral efficiency and channel capacity [2][3][4]. It is necessary to adopt these modulation schemes to commercialize multi-bit-per-symbol ultra-low latency optical transceiver systems.…”