Secrecy-Oriented Optimization of Sparse Code Multiple Access for Simultaneous Wireless Information and Power Transfer in 6G Aerial Access Networks

This article focuses on the simultaneous wireless information and power transfer (SWIPT) systems, which provide both the power supply and the communications for Internet-of-Things (IoT) devices in the sixth-generation (6G) network. Due to the extremely stringent requirements on reliability, speed, and security in the 6G network, aerial access networks (AANs) are deployed to extend the coverage of wireless communications and guarantee robustness. Moreover, sparse code multiple access (SCMA) is implemented on the SWIPT system to further promote the spectrum efficiency. To improve the speed and security of SWIPT systems in 6G AANs, we have developed an optimization algorithm of SCMA to maximize the secrecy sum rate (SSR). Specifically, a power-splitting (PS) strategy is applied by each user to coordinate its energy harvesting and information decoding. Hence, the SSR maximization problems in the SCMA system are formulated in terms of the PS and resource allocation, under the constraints on the minimum rates and minimum harvested energy of individual users. Then, a successive convex approximation method is introduced to transform the nonconvex problems to the convex ones, which are then solved by an iterative algorithm. In addition, we investigate the SSR performance of the SCMA system supported by our optimization methods, when the impacts from different perspectives are considered. Our studies and simulation results show that the SCMA system supported by our proposed optimization algorithms significantly outperforms the legacy system with uniform power allocation and fixed PS.

Wireless UAV Rotary Wing Communication with Ground Nodes Using Successive Convex Approximation and Energy Saving Mode

Communication with several ground nodes (GNs) is enabled through wireless communications by means of a rotary-wing unmanned aerial vehicle (UAV). For every GN, the requirements of communication throughput is satisfied while minimizing the communication and propulsion related energy thereby reducing the total energy consumption of the UAV. The total completion time of the mission, the GN time allocation for communication as well as the trajectory of UAV are optimized jointly to formulate the problem of energy minimization. The UAV rotary wing model of power consumption for propulsion power in a closed-form is also derived. The complexity of the problem increases with the involvement of several variables infinitely over time and the non-convex variables, making it challenging to be solved optimally. The hovering location sets are visited by the UAV and at each location, communication is established with the corresponding GNs. This simplified design for fly-hover-communicate is established for tackling the underlying issue. Convex optimization techniques and travelling salesman problem with neighborhood (TSPN) are leveraged for optimization of the trajectory that connects the hovering locations and the duration of hovering by means of the proposed algorithm design. Communication of the UAV during operation is considered as a general scenario. Discretization of the problem to its equivalent is done in the proposed novel path discretization technique by means of optimized variables of finite number. Further, a successive convex approximation (SCA) scheme is applied for obtaining a solution that is locally optimal. A comparison of the proposed design is performed with the benchmark schemes and it is found that they are outperformed based on numerical results.