Optimal trajectory and resource allocation for RSMA-UAV assisted IoT communications

Unmaned aerial vehicle (UAV) can be deployed as an aerial base station (BS) of Internet of Things (IoT) due to its high mobility and low cost, while the ground BSs are absent or overload. We propose a rate splitting multiple access (RSMA)-UAV assisted IoT communication model, where the UAV flies over the target area and provide communication services for multiple ground users in pairs. In the RSMA-UAV scheme, the information of each ground user is split into common information and private information. In a user pair, the common information is decoded by all the users and the private information is only decoded by a specific user. The RSMA-UAV can control the inter-user interference by adjusting the split of common and private information, thus improving the rate of ground users. We formulate an optimization problem to maximize the system throughput by jointly optimizing communication schedule, common rate, transmit power and UAV flight trajectory. By leveraging block coordinate descent technique, we decompose the non-convex optimization problem into some solvable subproblems, and propose an alternating iterative optimization algorithm to achieve the suboptimal solutions. The simulations have shown that the RSMA-UAV scheme can achieve higher throughout than the orthogonal multiple access (OMA)-UAV scheme, and improve the minimum average achievable rate of users compared with the non-orthogonal multiple access (NOMA)-UAV scheme.