Performance Analysis and Optimization of Multi-Antenna UAV-Aided Multi-User Backscatter SPC Systems.

This paper investigates the performance of a multi-antenna unmanned aerial vehicle (UAV)-aided backscatter short packet communication (SPC) system. The energy and radio frequency (RF) for the operations of backscatter devices are supported by UAV, and finite block length data are transmitted via uplink. The block error rate (BLER), throughput, goodput, reliability, latency, and age of information (AoI) are used to evaluate the proposed system performance, where the closed-form BLER expressions are approximated by the Gaussian- Chebyshev quadrature with line-of-sight (LoS) and non-LoS (NLoS) probabilities. We formulate optimization problems to maximize the throughput subject to the number of transmit bits and the UAV altitude and to minimize BLER subject to the UAV altitude, then solve them by using the one-dimensional search method. Monte Carlo simulations verify the accuracy of analysis results. The results show that using multi-antennas and maximal-ratio transmission (MRT) significantly improves the BLER. In addition, choosing a suitable altitude of UAV and relevant transmission bit can provide the best BLER and throughput or goodput. Finally, the impacts of UAV velocity, the operating environments, and LoS probability on the system performance are significant.