6G Network Architecture Using FSO-PDM/PV-OCDMA System with Weather Performance Analysis

This paper presents a novel 160 Gbps free space optics (FSO) communication system for 6G applications. Polarization division multiplexing (PDM) is integrated with an optical code division multiple access (OCDMA) technique to form a PDM-OCDMA hybrid. There are two polarization states: one is X-polarization generated from adjusting the azimuthal angle of a light source at 0° while the other is Y-polarization which is generated by adjusting the azimuthal angle of a light source at 90°. Each polarization state is used for the transmission of four independent users. Each channel is assigned by permutation vector (PV) codes and carries 20 Gbps data. Four different weather conditions are considered for evaluating the performance of our proposed model. These weather conditions are clear air (CA), foggy conditions (low fog (LF), medium fog (MF), and heavy fog (HF)), dust storms (low dust storm (LD), moderate dust storm (MD), heavy dust storm (HD)), and snowfall (wet snow (WS) and dry snow (DS)). Bit error rate (BER), Q-factors, maximum propagation range, channel capacity, and eye diagrams are used for evaluating the performance of the proposed model. Simulation results assure successful transmission of 160 Gbps overall capacity for eight channels. The longest FSO range is 7 km which occurred under CA while the minimum is achieved under HD, which is 0.112 km due to large attenuation caused by HD. Within fog conditions, the maximum propagation distances are 1.525 km in LF, 1.05 km in MF, and 0.85 km in HF. Likewise, under WS and DS, the proposed system can support transmission distances of 1.15 km and 0.28 km, respectively. All these transmission distances are achieved at BER less than 10−5

Enhanced Spectral Amplitude Coding OCDMA System Utilizing a Single Photodiode Detection

In this paper, the performance of a spectral amplitude coding-optical code division multiple access (SAC-OCDMA) system is investigated utilizing a single photodiode (SPD) detection technique. The proposed system uses enhanced double weight (EDW) codes as signature codes with three simultaneous users to overcome both phase-induced intensity noise (PIIN) and multiple access interference (MAI). In addition, a dispersion compensating fiber (DCF) is used in order to decrease the group velocity dispersion (GVD) caused in the single mode fiber. An erbium-doped fiber amplifier (EDFA) is used to overcome the attenuation. The use of both DCF and EDFA leads to an appreciable enhancement in the system performance. The system performance is evaluated through its bit error rate (BER), Q-factor, and received power. A comparison between the EDW codes and modified double weight (MDW) codes on the SAC-OCDMA system is demonstrated. Simulation is carried out through Optisystem ver. 7. The simulation results show that: (a) using an avalanche photodiode (APD) over PIN photodiode allows data transmission over longer distances; (b) the use of DCF improves the system BER;(c) using MDW codes gives better BER than using EDW codes

Reduction of Complexity Design of SAC OCDMA Systems by Utilizing Diagonal Permutation Shift (DPS) Codes with Single Photodiode (SPD) Detection Technique

In this paper, a diagonal permutation code is presented for spectral amplitude coding optical code division multiple access (SAC-OCDMA) employing a single photodiode (SPD) detection technique. It is characterized by practical code length and ideal in-phase cross correlation (CC) that results in multiple access interference (MAI) suppression. A diagonal permutation shift (DPS) code can be constructed using both prime codes and some matrix operations. In addition, it can be easily implemented as it exists for prime numbers P, which limits the addressing probability of codes to P2. Fiber Bragg gratings (FBGs) are used for code encoding and decoding. Simulation analysis that calibrates with BER, Q-factor, and eye diagram proves that DPS code using SPD technique is able to maintain error free transmission compared to the complementary detection scheme (CDS) technique. It is reported that a reduction of fiber Bragg grating (FBG) sets by 41.6% was achieved for SPD over CDS techniques

Reduction of Complexity Design of SAC OCDMA Systems by Utilizing Diagonal Permutation Shift (DPS) Codes with Single Photodiode (SPD) Detection Technique

In this paper, a diagonal permutation code is presented for spectral amplitude coding optical code division multiple access (SAC-OCDMA) employing a single photodiode (SPD) detection technique. It is characterized by practical code length and ideal in-phase cross correlation (CC) that results in multiple access interference (MAI) suppression. A diagonal permutation shift (DPS) code can be constructed using both prime codes and some matrix operations. In addition, it can be easily implemented as it exists for prime numbers P, which limits the addressing probability of codes to P2. Fiber Bragg gratings (FBGs) are used for code encoding and decoding. Simulation analysis that calibrates with BER, Q-factor, and eye diagram proves that DPS code using SPD technique is able to maintain error free transmission compared to the complementary detection scheme (CDS) technique. It is reported that a reduction of fiber Bragg grating (FBG) sets by 41.6% was achieved for SPD over CDS techniques

Capacity Enhancement Based on Using Hybrid SCM With SAC-OCDMA Using Different Codes for OFC and FSO Transmission Systems

A new hybrid optical fiber communication (OFC) and free space optics (FSO) communication systems are proposed for enhancing the transmission capacity. It is based on using subcarrier modulation (SCM) with spectral amplitude coding based optical code division multiple access (SAC-OCDMA) technique using three different codes. Permutation vector (PV) code, zero cross correlation (ZCC) code, and fixed right shift (FRS) code are used. The performance is evaluated for various numbers of users, data rate, effective power levels, number of subcarriers, and number of carrier channels. Additionally, the effects under different fog conditions including light fog (LF), medium fog (MF), and heavy fog (HF) are evaluated. Moreover, the proposed FSO system achieves ranges of 1.8 km, 1.05 km, and 0.8 km under LF, MF, and HF conditions respectively. Our results show that the proposed OFC system supports 7, 6, and 5 simultaneous users with PV, ZCC, and FRS codes respectively. Similarly, each user carries 5 channels, and each channel carries 14 subcarriers with 1 Gbps information per subcarrier when PV code is adopted. As for FSO transmission, the proposed hybrid system can support up to 22, 18, and 14 users under LF, MF, and HF respectively. Each user also carries information from 5 channels. All results are obtained at BER less than $3\times {10}^{-3}$

Capacity Enhancement for Free Space Optics Transmission System Using Orbital Angular Momentum Optical Code Division Multiple Access in 5G and beyond Networks

This paper introduces a novel free space optics (FSO) communication system for future-generation high-speed networks. The proposed system integrates orbital angular momentum (OAM) modes with an optical code division multiple access (OCDMA) technique. Two OAM beams are used (LG0,0 and LG0,10), each of which is used for transmitting three independent channels. Each channel is assigned by fixed right shift (FRS) codes and carries 10 Gbps of information data. The performance of the proposed model is evaluated under different foggy and dust storm conditions. Furthermore, the performance of two cities with different geographical locations, Alexandria city in Egypt and Srinagar city in India, is investigated to demonstrate its ability to be implemented in future generations. Bit error rate (BER), eye diagrams, received optical power (ROP), and channel capacity are used for studying the performance of the proposed system. The observed simulation results show successful transmission of 60 Gbps overall capacity with the longest propagation FSO range for Alexandria city, which is 1400 m. Because dust storms have a large attenuation when compared to different foggy conditions, the proposed model had the shortest propagation range of 315 m under low dust (LD), 105 m under moderate dust (MD), and 40 m under heavy dust (HD). Furthermore, the cloudy weather conditions that affect Srinagar city, which is considered a hilly area, make our suggested model achieve 1000 m

A QoS Classifier Based on Machine Learning for Next-Generation Optical Communication

Code classification is essential nowadays, as determining the transmission code at the receiver side is a challenge. A novel algorithm for fixed right shift (FRS) code may be employed in embedded next-generation optical fiber communication (OFC) systems. The code aims to provide various quality of services (QoS): audio, video, and data. The Q-factor, bit error rate (BER), and signal-to-noise ratio (SNR) are studied to be used as predictors for machine learning (ML) and used in the design of an embedded QoS classifier. The hypothesis test is used to prove the ML input data robustness. Pearson’s correlation and variance-inflation factor (VIF) are revealed, as they are typical detectors of a data multicollinearity problem. The hypothesis testing shows that the statistical properties for the samples of Q-factor, BER, and SNR are similar to the population dataset, with p-values of 0.98, 0.99, and 0.97, respectively. Pearson’s correlation matrix shows a highly positive correlation between Q-factor and SNR, with 0.9. The highest VIF value is 4.5, resulting in the Q-factor. In the end, the ML evaluation shows promising results as the decision tree (DT) and the random forest (RF) classifiers achieve 94% and 99% accuracy, respectively. Each case’s receiver operating characteristic (ROC) curves are revealed, showing that the RF outperforms the DT classification performance

Performance evaluation of a 160-Gbit/s OCDMA-FSO system via Laguerre-Gaussian beams under weather conditions

For capacity enhancement of free space optics (FSO) communication, a new model based on using four Laguerre-Gaussian (LG) beams, each carries four different users use optical code division multiplexing (OCDMA) techniques, is proposed. Additionally, the permutation vector (PV) codes that have zero cross correlation with direct detection (DD) technique are assigned to the OCDMA system. Each user carries 10 Gbps information data, so the overall capacity is 4 LG beams × 4 users (OCDMA) × 10 Gbps = 160 Gbps. Furthermore, the proposed model is simulated under the effects of different attenuations caused by different weather conditions and the performance is studied. The conducted results reveal successful transmission of 13 km under clear air (CA), 1.75 km under heavy haze (HH), 1.1 km under heavy rain (HR), and 0.9 km under heavy fog (HF) with an overall system capacity of 160 Gbps. These results were obtained with an acceptable log bit error rate (BER) less than −9 and quality (Q)-factor nearly 6