Twisted light beams such as optical angular momentum (OAM) with numerous possible orthogonal states have drawn the prodigious contemplation of researchers. OAM multiplexing is a futuristic multi-access technique that has not been scrutinized for optical satellite communication (OSC) systems thus far, and it opens up a new window for ultra-high-capacity systems. This paper presents the 4.8 Tbps (5 wavelengths × 3 OAM beams × 320 Gbps) ultra-high capacity OSC system by incorporating polarization division multiplexed (PDM) 256-Quadrature amplitude modulation (256-QAM) and OAM beams. To realize OAM multiplexing, Laguerre Gaussian (LG) transverse mode profiles such as LG00, LG140, and LG400 were used in the proposed study. The effects of the receiver’s digital signal processing (DSP) module were also investigated, and performance improvement was observed using DSP for its potential to compensate for the effects of dispersion, phase errors, and nonlinear effects using the blind phase search (BPS), Viterbi phase estimation (VPE), and the constant modulus algorithm (CMA). The results revealed that the proposed OAM-OSC system successfully covered the 22,000 km OSC link distance and, out of three OAM beams, fundamental mode LG00 offered excellent performance. Further, a detailed comparison of the proposed system and reported state-of-the-art schemes was performed.

FSO (free space optical) communication holds emanated position in the role of propitious innovation with exorbitant-speed using the data transmission mechanism without the wire, propounding an accomplishable explication to the surging need for bandwidth in communication networks. This research paper probes into the improvements and obstacles in FSO communication systems, pursuing to anticipate a compendious encapsulation of the state-of-the-art establishment in this discipline. The evaluation incorporates a meticulous inspection of vital constituents such as laser sources, modulators, and receivers, elucidating their contribution to accomplishing coherent data transfer. The scrutinizing also investigates innumerable atmospheric circumstances affecting FSO links, including weather conditions and turbulence, and puts forward ingenious approaches to alleviate their repercussion on communication performance. Furthermore, the paper explores the homogenization of ultra-modern signal processing techniques to amplify the credibility and robustness of FSO systems, corroborating seamless communication even in challenging environments. Moreover, the research inquiries into the neoteric experimental framework and real-world execution of FSO communication, shedding light on heuristic contemplation, and substantiating theoretical unearthing. The conclusion of this research shells out treasures perception of the ongoing attempt to optimize FSO communication for variegated applications, including, inter-satellite communication, high-speed internet access, and last-mile connectivity. As FSO perpetuates progress, this paper suffices as a recent and inclusive resource for researchers, engineers, and policymakers maneuvering the edges of optical communication technologies.

The vehicular ad hoc network is an emerging area of technology that provides intelligent transportation systems with vast advantages and applications. Frequent disconnections between the vehicular nodes due to high-velocity vehicles impact network performance. This can be addressed by efficient clustering techniques. Several recent studies have attempted to develop optimal clustering algorithms to improve network performance metrics using soft computing techniques. Although sufficient work on soft computing techniques has been carried out, it seems less commonplace to find an analysis of various algorithms’ network parameters together. This paper provides a systematic analysis of the clustering-based routing protocols used in vehicular networks that are aware of soft computing techniques. The categorization is performed according to various soft computing techniques: particle swarm optimization, k-means, neural networks, artificial bee colony, genetic algorithm, firefly algorithm, and fuzzy logic. A comparative study of soft computing strategies is also provided in the survey with a focus on their objectives, along with their strengths and limitations. This survey makes it easier for researchers to pick the required soft computing technique used in vehicular networks in order to improve metrics such as packet delivery ratio, end-to-end delay, throughput, cluster lifetime, and message overhead.

In this work, an optical angular momentum (OAM) multiplexing enabled 400 Gbps free space optical communication (FSOC) system has been proposed using polarization division multiplexed (PDM) quadrature phase shift keying (QPSK) and digital signal processer (DSP) in the receiver. Different weather conditions such as clear weather, rain and fog are explored in proposed system and their deteriorating effects are observed in terms of log BER. Laguerre Gaussian (LG) beams (LG0,0, LG0,13, LG0,40, and LG0,80) are employed to realize four channel FSOC system and OAM multiplexing. Results revealed that integration of DSP in the PDM-QPSK receiver cause significant improvement in symbols placements in constellation and moreover proposed system successfully covered 3500 m, 3000 and 1200 m in FSO under clear weather, rain and fog, respectively.