Non-terrestrial networks (NTNs) have gained significant attention for their scalability and wide coverage in next-generation communication systems. A large number of NTN nodes, such as satellites, are required to establish a global NTN, but not all operators have the capability to deploy such a system. Therefore, cooperation among multiple operators, facilitated by an orchestrator, enables the construction of virtually large-scale constellations. In this paper, we propose a weak-control-based orchestration framework that coordinates multiple NTN operators while ensuring that operations align with the policies of both the orchestrator and the individual operators. Unlike centralized orchestration frameworks, where the orchestrator determines the entire route from source to destination, the proposed framework allows each operator to select preferred routes from multiple candidates provided by the orchestrator. To evaluate the effectiveness of our proposed framework, we conducted numerical simulations under various scenarios and network configurations including dynamic NTN environments with time-varying topologies, showing that inter-operator cooperation improves the availability of feasible end-to-end routes. Furthermore, we analyzed the iterative negotiation process to address policy conflicts and quantitatively demonstrated the “price of autonomy,” where strict individual policies degrade global feasibility and performance. The results also demonstrate that outcomes of the proposed framework depend on the operators’ policies and that hop count and latency increase as the number of operators grows. These findings validate the proposed framework’s ability to deliver practical benefits of orchestrated multi-operator collaboration in future NTN environments.

In this paper, coordinated multi-point transmission (CoMP) with attribution macro cell switching in distributed antenna transmission is proposed. The proposed scheme is applied to a macro cell system in which each macro cell consists of multiple micro cells. In the proposed scheme, macro cells can be expanded and overlapped with each other, and each micro cell may switch its attribution macro cell. Inter-cell interference is mitigated in conjunction with CoMP transmission. Numerical results obtained through computer simulation show that the largest improvement in a system throughput is realized with three user equipments per macro cell when an inter-antenna distance is 50 meters. The switching frequency corresponds to the amount of the improvement in the throughput. The switching happens less frequently with a longer inter-antenna distance. Thus, the proposed scheme improves the system throughput than the conventional scheme in a dense distributed antenna system.

In this paper, user set elimination in the allocation sequences of round-robin (RR) scheduling for distributed antenna transmission (DAT) is proposed. In prior research, the initial phase selection of the user equipment (UE) allocation sequences in RR scheduling has been investigated. However, all of UE sets are included without taking their throughputs into account. Thus, a UE set is assigned even through its total throughput is the lowest. The proposed scheme eliminates the specific UE sets from the RR scheduling sequence according to the expected total throughput of those UE sets. In addition, the initial phase selection is applied to the remaining UE sets. Numerical results obtained through computer simulation show that fairness index as well as system throughput improve when the ratio of eliminated UE sets is small.

In this paper, a macro cell switching scheme for distributed antennas is proposed. In conventional distributed antenna transmission (DAT), a macro cell to which each antenna belongs is fixed. Though a cell-free system has been investigated because of its higher system throughput, the complexity of front-haul can be inevitably large. To increase the flexibility of resource allocation in the DAT with moderate front-haul complexity, the macro cell switching of distributed antennas (DAs) is proposed. In the proposed scheme, DAs switch their attribution macro cells depending on the amount of pre-assigned resources. Numerical results obtained through computer simulation show that the proposed scheme realizes a better system throughput than the conventional system especially when the number of user equipments (UEs) is smaller.

One of key technologies in the fifth generation mobile communications is a distributed antenna system (DAS). In the DAS inter-user interference effects on its spectrum efficiency as distributed antennas are located closely. Round-robin (RR) scheduling is known as a scheme that achieves a trade-off between computational complexity and spectrum efficiency. In this research user equipment (UE) allocation scheme for RR scheduling are proposed. The proposed scheme determines the phases of UE allocation sequence that is pre-determined for low complexity. Numerical results obtained through computer simulation have shown that maximum selection that sequentially searches the phase with the maximum tentative throughput realizes the largest spectrum efficiency next to full search. The system throughput increases as the number of UEs increases in 2-user RR scheduling.