Resource Management Optimization for Interference-Limited Multi-User Satellite Networks (ROIMUS)

未来的卫星通信有两个主要特性。首先，卫星上的馈电数量，即天线单元的数量大约有几百个。此外，在大量载波的时隙中传输是可能的。其次，必须服务静态和移动用户，其信道具有视距连接的特性，即信道协方差矩阵为秩一。针对这类卫星系统，基于鲁棒问题公式，考虑波束形成和用户调度的联合设计，能够同时处理静态和移动用户。基于对偶分解方法和目标的单调性，导出了全局最优解。由于维度大，即有许多天线、运营商和用户，因此必须采用启发式方法来寻找低复杂度的解决方案。另一方面，问题的大维度允许进行大的系统分析。除了自适应波束形成和最先进的带调度的固定波束形成外，还研究了一种地面站可以在一组离散波束形成模式中进行选择的离散自适应波束形成方案。此外，除了传统的单卫星设置外，还考虑了卫星集群的情况。当用户由几颗卫星服务时，卫星群设计的额外困难是单独的功率限制和波束形成器的结构限制。此外，还研究了控制卫星的地面站的不同合作水平。

Future satellite communications have two major properties. First, the number of feeds, i.e., the number of antenna elements, at the satellite are in the order of several hundreds. Additionally, transmission is possible in time slots on a large number of carriers. Second, static and mobile users must be served, whose channels have the properties of a line-of-sight connection, i.e., the channel covariance matrices are rank one.For such satellite systems, the joint design of beamforming and user scheduling is considered that is able to deal with static and mobile users based on a robust problem formulation. Globally optimal solutions are derived based on a dual decomposition approach and monotonicity properties of the objective. Due to the large dimensions, i.e., many antennas, carriers, and users, heuristics must be employed to find low-complexity solutions. On the other hand, the large dimensionality of the problem allows for a large system analysis.Besides the adaptive beamforming and the state-of-the-art fixed beamforming with scheduling, a discretely adaptive beamforming scheme is investigated where the ground station can choose over a set of discrete beamforming patterns. Moreover, the case of a satellite cluster is considered besides the conventional single satellite setup. The additional difficulties of the design for a satellite cluster, where the users are served by several satellites, are the separate power constraints and the structural constraints of the beamformer. Additionally, different cooperation levels of the ground stations controlling the satellites are investigated.