One of the main characteristics of the DVB-S2/S2X standard is the capability of using the Adaptive Coding and Modulation (ACM) technique. Differently from Variable Coding and Modulation (VCM), ACM provides a feedback path in the return channel for dynamically varying protection error levels in accordance with different channel conditions. In this article, a double-layer packet scheduling mechanism able to support different QoS levels monitoring the propagation and channel conditions is proposed. It consists of a Two-Stage Scheduler (TSS) approach and proposes two novel schedulers to be used in the first and second stage: an Adaptive Priority-based Scheduling (APS) able to account QoS requirements is proposed for the first stage; an improved version of Proportional Fair queueing (PF) called PF with Padding and Packing (PF-PP), able to select and transmit in the forward link frames in accordance to an appropriate fair policy is designed for the second stage. Performed experiments show an improvement of the overall system performance in terms of packet drop rate, delay jitter, and packets delay.

中文翻译：

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DVB-S2/S2X卫星架构的两阶段调度方案设计

DVB-S2/S2X 标准的主要特征之一是能够使用自适应编码和调制 (ACM) 技术。与可变编码和调制 (VCM) 不同，ACM 在返回信道中提供反馈路径，用于根据不同的信道条件动态改变保护错误级别。在本文中，提出了一种能够支持不同 QoS 级别监视传播和信道条件的双层数据包调度机制。它由一个双阶段调度器 (TSS) 方法组成，并提出了两个用于第一阶段和第二阶段的新颖调度器：第一阶段提出了能够考虑 QoS 要求的基于自适应优先级的调度 (APS)；比例公平排队 (PF) 的改进版本，称为 PF with Padding and Packing (PF-PP)，能够根据适当的公平策略在前向链路帧中选择和传输是为第二阶段设计的。执行的实验表明，在丢包率、延迟抖动和数据包延迟方面，整体系统性能有所改善。