Combining transmit antenna selection and full-duplex aerial relay drone for performance enhancement of multiuser NOMA millimeter-wave communications

Abstract

In this article, multiple antennas are proposed to utilize the millimeter-wave (MW) communication in a full-duplex aerial relay drone (FD-ARD) multi-user non-orthogonal multiple access (NOMA) system. Notably, the transmit antenna selection (TAS) technique is also incorporated to yield a significant boost in the system performance and a noteworthy reduction in signal processing complexity at the user end. The mathematical formulas of outage probability (OP) and achievable capacity (AC) of the proposed system are derived under the effect of channel and system parameters that are recommended for the fifth generation (5G) standard and the beyond 5G (B5G) proposals. All derived formulas are validated by using Monte-Carlo simulations. Numerical results show that TAS offers a substantial advantage over the scenarios without TAS. This holds even in the presence of several adverse factors, including the attributes of NOMA, the residual self-interference (RSI) stemming from full-duplex (FD) transmissions, the utilization of high carrier frequencies within MW bands, and the elevated altitude of the drone. The OP of systems equipped with TAS remains impressively below 10−11, whereas systems lacking TAS exhibit a substantially higher OP value of 10−4. Furthermore, the AC is notably elevated with the incorporation of TAS, as compared to scenarios where TAS is absent. However, the gap between the performance of the systems with and without TAS becomes insignificant when the RSI is sufficiently high. Consequently, this work can recommend the suitable transmit power corresponding to a specific RSI level and other system requirements to save energy and avoid saturated performance. In addition, the specific effect of high carrier frequencies in MW bands, positions of the drone, numbers of transmit/receive antennas, and RSI levels are deeply investigated to achieve useful insights into the behaviors of the proposed system.