UAV-Relay-Assisted Live Layered Video Multicast for Cell-Edge Users in NOMA Networks

In this paper, a live layered video multicast framework based on unmanned aerial vehicle (UAV) relays is presented for on-orthogonal multiple access (NOMA) networks, aiming to maximize the aggregated video reception quality for cell-edge users. A visualizable graph model is constructed to characterize the coupling of the deployment of UAVs and their association with multicast groups with interference cancellation. Based on this graph model, the problem of maximizing multicast group video reception quality is modeled as a clique-based nonlinear integer programming and decoupled into UAV placement and UAV-group association subproblem and subchannel allocation subproblem. For mathematical traceability, the former is transformed into a unique maximum weight clique problem under the available UAV number constraint, solved by an improved branch-and-bound algorithm. For the latter, a heuristic resource-matching strategy is designed to obtain a near-optimal subchannel allocation with low computational complexity. Simulation results demonstrate that the proposed scheme outperforms mainstream benchmarks in terms of aggregate peak signal-to-noise ratio (PSNR), spectrum utilization, network coverage, and adaptability.