Design of a High-Speed OFDM-SAC-OCDMA-Based FSO System Using EDW Codes for Supporting 5G Data Services and Smart City Applications

Abstract

A novel free space optics (FSO) system is introduced in this article by combining orthogonal frequency division multiplexing (OFDM) with spectral amplitude coding optical code division multiple access (SAC-OCDMA) to be implemented in 5G technology and smart cities. Enhanced double-weight (EDW) codes are used as signature codes, while for the detection technique, single photodiode detection (SPD) is applied for the SAC-OCDMA system. OFDM with a four-quadrature amplitude modulation (4-QAM) scheme is assigned to the three users in the SAC-OCDMA system, each carrying 15 Gbps. Adverse weather conditions, such as clear, fog, haze, rain, and dust storm, that affect the FSO channel are considered. The performance of the proposed system is evaluated in terms of log of bit error rate and received power at different propagation distances. The simulation results show successful transmission of 3 × 15 Gbps with a propagation range of 3.45 km under clear air and 1.316, 1.045, and 0.7 km under rain conditions (light, medium, and heavy rain) with a received power of −12.6 dBm. As for haze conditions, the range and received power are 2.391 km with −13 dBm for low haze, 1.591 km with −12.7 dBm for medium haze, and 1.025 km with −12.6 dBm for heavy haze. The range is reduced and becomes 1.085, 0.784, and 0.645 km under fog conditions (light, medium, and heavy fog) with −12.6 dBm received power. Furthermore, the system achieved a range of 0.681, 0.232, and 0.102 km under dust conditions (light, medium, and heavy dust) with a received power of −16 dBm.

Performance Enhancement of FSO Communication System Under Rainy Weather Environment Using a Novel Encryption Technique

“…( 17). After propagating in the atmosphere, the signal is then received with received optical power, 𝑃𝑃 𝑟𝑟𝑟𝑟 𝑂𝑂 , in dBm that is expressed as [12,34]…”

“…However, despite its benefits, FSO transmission is vulnerable to atmospheric attenuation, leading to signal degradation, a higher Bit Error Rate (BER), and loss of information. Various atmospheric conditions, including haze, dust storms, fog, and rain, all contribute to the weakening of the transmitted signal [9][10][11][12]. Different techniques have therefore been proposed to improve FSO performance in adverse weather conditions such as: Adaptive Modulation, Wavelength Diversity, Error Correction Coding, etc… Furthermore, the extensive use of wireless communication technologies has spurred the rapid expansion of image transmission as a prominent application.…”

Massive capacity of novel three‐dimensional OCDMA‐FSO system for next generation of high‐data wireless networks

“…Singh et al's 45 study a novel FSO system by combining orthogonal frequency division multiplexing (OFDM) with spectral amplitude coding optical code division multiple access (SAC‐OCDMA) employing Enhanced double‐weight (EDW) codes for 5G technology and smart cities.…”

Influence of different codes on the performance of SAC‐OCDMA over FSO link

“…12 SAC-OCDMA performance has been observed using different signature codes. [10][11][12][13][14][15][16] The results of these studies show that prime code families allow more users to share the channel. Though a thorough review of the literature has been conducted, no comprehensive study has been found on SAC-OCDMA systems for various types of codes and a range of system parameters, such as link distance, number of simultaneous users, divergence angle, transmission length, code weight, etc., that can be used to achieve system performance in a free space channel environment.…”

“…Using DEU code, the performance of SAC‐OCDMA was examined in Hassan and Kottakkaran 12 . SAC‐OCDMA performance has been observed using different signature codes 10–16 . The results of these studies show that prime code families allow more users to share the channel.…”