This letter presents a federated learning-basd data-accumulation scheme that combines drones and blockchain for remote regions where Internet of Things devices face network scarcity and potential cyber threats. The scheme contains a two-phase authentication mechanism in which requests are first validated using a cuckoo filter, followed by a timestamp nonce. Secure accumulation is achieved by validating models using a Hampel filter and loss checks. To increase the privacy of the model, differential privacy is employed before sharing. Finally, the model is stored in the blockchain after consent is obtained from mining nodes. Experiments are performed in a proper environment, and the results confirm the feasibility of the proposed scheme.

A cooperative non-orthogonal multiple access (CNOMA) system and an orbital angular momentum (OAM) -based multiple-input multiple-output multiplexing system is proposed as full-duplex relaying (referred to as CNOMF) by the cell center user to the cell edge user in this letter. The proposed CNOMF scheme can significantly improve the capacity of cell edge user and sum channel capacity via user-assisted decode and forward based full-duplex relaying by utilizing different ranges of OAM modes for a 6G (Sixth generation) wireless communication system, compared to other existing schemes (For example, CNOMA-MIMO with FDR, and orthogonal multiple access with OAM-MIMO and half duplex relaying); this was demonstrated via numerical result analysis.

In this study, an orbital angular momentum-based multiple-input multiple-output (OAM-MIMO) multiplexing system is integrated with non-orthogonal multiple access (NOMA) to enhance the user and sum channel capacities of the downlink NOMA for multiple users. The user and sum capacities of the proposed NOMA-OAM-MIMO scheme is analyzed and compared with other conventional schemes such as conventional NOMA with MIMO, and conventional orthogonal multiple access with OAM-MIMO multiplexing.

A well-functioning smart grid is an essential part of an efficient and uninterrupted power supply for the key enablers of smart cities. To effectively manage the operations of a smart grid, there is an essential requirement for a seamless wireless communication system that provides high data rates, reliability, flexibility, massive connectivity, low latency, security, and adaptability to changing needs. A contemporary review of the utilization of emerging 6G wireless communication for the major applications of smart grids, especially in terms of massive connectivity and monitoring, secured communication for operation and resource management, and time-critical operations, are presented in this paper. This article starts with the key enablers of the smart city, along with the necessity of the smart grid for the key enablers of it. The fundamentals of the smart city, smart grid, and 6G wireless communication are also introduced in this paper. Moreover, the motivations to integrate 6G wireless communication with the smart grid system are expressed in this article as well. The relevant literature overview, along with the novelty of this paper, is depicted to bridge the gap of the current research works. We describe the novel technologies of 6G wireless communication to effectively perform the considered smart grid applications. Novel technologies of 6G wireless communication have significantly improved the key performance indicators compared to the prior generation of the wireless communication system. A significant part of this article is the contemporary survey of the considered major applications of a smart grid that is served by 6G. In addition, the anticipated challenges and interesting future research pathways are also discussed explicitly in this article. This article serves as a valuable resource for understanding the potential of 6G wireless communication in advancing smart grid applications and addressing emerging challenges.

In this letter, non-orthogonal multiple access (NOMA) is integrated with orbital angular momentum (OAM)-based multiple-input multiple-output (MIMO), denoted as OAM-MIMO, and OAM with index modulation, denoted as OAM-IM, to improve its downlink channel capacities for multiple users. The user and sum channel capacities are evaluated and compared with those of existing schemes such as NOMA with OAM-MIMO, conventional NOMA with MIMO, and conventional orthogonal multiple access with OAM-IM. The simulation results show that the proposed scheme outperforms the conventional schemes in terms of both individual user and sum channel capacities.