Amirkabir University of Technology AUT Journal of Electrical Engineering 2588-2910 58 Special Issue 1 2026 05 01 Achievable Rate Region for Wireless Multiple Access Channels with UAV Relay and k Independent Transmitters 39 50 5989 10.22060/eej.2026.23943.5643 EN Padideh Nobakht Dr, Department of Electrical Engineering, sadjad University, Mashhad, Iran 0009-0008-5033-3547 Amir Masoud Aminian Modarres Dr, Department of Electrical Engineering, sadjad University, Mashhad, Iran 0000-0002-1180-4106 Ghosheh Abed Hodtani Profssor, Department of Electrical Engineering, Ferdowsi University, Mashhad, Iran 0000-0002-4337-1624 Journal Article 2025 03 02 This paper considers and characterizes a multiple access relay channel (MARC) with $k$ transmitters, one UAV relay, and a terrestrial receiver, where we derive a new achievable rate region for the continuous alphabet wireless with an unmanned aerial vehicle (UAV) relay. The derived rate region is then evaluated numerically and compared with those of multiple access channels (MAC) and MARC with terrestrial relays. The results show that the presence of a UAV relay increases the achievable rate region of MAC systems by exploiting higher line-of-sight (LoS) channel quality and time-varying spatial link gains due to the UAV’s position. This improvement in the achievable region is not merely due to the UAV’s presence but arises from the different channel geometry and dynamic link conditions introduced by the UAV relay compared with terrestrial relays. https://eej.aut.ac.ir/article_5989_1ae6464c6b5d51b363d7d96f97132c75.pdf