With the commercial deployment of low earth orbit (LEO) satellites, the future integrated 6G-satellite system represents an excellent solution for ubiquitous connectivity and high-throughput data service to massive users. Due to the heterogeneity of users’ traffic profiles, uneven traffic distribution among beams or users often occurs in LEO satellite systems. Conventional satellite payloads with fixed beam radiation patterns may result in large gaps between requested and allocated capacity. The advances of flexible satellite payloads with dynamic beamforming capabilities enable spot beams to adjust their coverage and adaptively schedule users, thus offering spatial-temporal domain flexibility. Motivated by this, as an early attempt, we investigate how adaptive beam patterns with flexible user scheduling schemes can help alleviate mismatches of requested-transmitted data in uneven-traffic and full-frequency reuse LEO systems. We formulate an optimization problem to jointly determine beam patterns, power allocation, user-LEO association, and user-slot scheduling. The problem is identified as mixed-integer nonconvex programming. We propose an efficient iterative algorithm to solve the problem by first determining beam patterns and user associations at the frame scale, followed by optimizing power allocation and user scheduling at the timeslot scale. The four-decision components are iteratively updated to improve the overall performance. Numerical results demonstrate the benefits brought by adaptive beam patterns and their effectiveness in reducing the mismatch effect in uneven-traffic LEO systems.

中文翻译：

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不均匀流量低地球轨道卫星系统的时空资源优化：波束方向图选择和用户调度

随着低地球轨道（LEO）卫星的商业部署，未来的综合6G卫星系统为海量用户提供了无处不在的连接和高吞吐量数据服务的优秀解决方案。由于用户流量分布的异构性，LEO卫星系统中经常会出现波束或用户之间流量分布不均匀的情况。具有固定波束辐射方向图的传统卫星有效载荷可能会导致请求的容量和分配的容量之间存在较大差距。具有动态波束成形功能的灵活卫星有效载荷的进步使点波束能够调整其覆盖范围并自适应地调度用户，从而提供时空域灵活性。受此启发，作为一项早期尝试，我们研究了具有灵活用户调度方案的自适应波束方向图如何帮助减轻不均匀流量和全频率复用低轨系统中请求传输数据的不匹配。我们制定了一个优化问题来共同确定波束方向图、功率分配、用户-LEO 关联和用户时隙调度。该问题被识别为混合整数非凸规划。我们提出了一种有效的迭代算法来解决该问题，首先确定帧尺度的波束方向图和用户关联，然后在时隙尺度优化功率分配和用户调度。四决策组件不断迭代更新，以提高整体性能。数值结果证明了自适应波束方向图带来的好处及其在减少不均匀交通 LEO 系统中失配效应方面的有效性。