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The main challenge for maintenance of distributed photovoltaic (PV) system lies in data collection. This letter considers unmanned aerial vehicle (UAV) to relay the maintenance data by visible light communication (VLC) under the requirements of ultra-reliability and low-latency. With finite blocklength, total error probability is minimized to ensure the system reliability by jointly optimizing blocklength allocation and UAV deployment. To search optimal solution, this letter divides the formulated problem into two sub-problems and proposes a global iterative algorithm based on alternating direction method of multipliers (ADMM) and random perturbation. Simulation results show that the proposed method is comparable to existing literature with better convergence and lower complexity.

Excited states (ESs) of two- and three-dimensional (2D and 3D) solitons of the semivortex (SV) and mixed-mode (MM) types, supported by the interplay of the spin–orbit coupling (SOC) and local nonlinearity in binary Bose–Einstein condensates, are unstable, on the contrary to the stability of the SV and MM solitons in their fundamental states. We propose a stabilization strategy for these states in 3D, combining SOC and long-range Rydberg–Rydberg interactions (RRI), in the presence of a spatially-periodic potential, that may include a parity-time (PT)-symmetric component. ESs of the SV solitons, which carry integer vorticities S and S + 1 in their two components, exhibit robustness up to S = 4. ESs of MM solitons feature an interwoven necklace-like structure, with the components carrying opposite fractional values of the orbital angular momentum. Regions of the effective stability of the 3D solitons of the SV and MM types (both fundamental ones and ESs), are identified as functions of the imaginary component of the PT -symmetric potential and strengths of the SOC and RRI terms. • We report robust 3D vortex solitons in a Rydberg-excited BECs. • The system contains spin-orbital coupling and PT-symmetric potential. • 3D semivortex (SV) and mixed-mode (MM) solitons are found. • These solitons exhibit robustness up to vorticity S=4. • Regions of the effective stability of the 3D solitons are identified. [ABSTRACT FROM AUTHOR]