As the transition from 5G to 6G unfolds, a substantial increase in Internet of Things (IoT) devices is expected, enabling seamless and pervasive connectivity across various applications. Accommodating this surge and meeting the high capacity demands will necessitate the integration of NonTerrestrial Networks (NTNs). However, the extensive coverage area of satellites, relative to terrestrial receivers, will lead to a high density of users attempting to access the channel at the same time, increasing the collision probability. In turn, the deployment of mega constellations make it possible for ground users to be in visibility of more than one satellite at the same time, enabling receiver diversity. Therefore, in this paper, we evaluate the impact of multi-receivers in scenarios where IoT nodes share the channel following a non-orthogonal multiple access (NOMA)irregular repetition slotted ALOHA (IRSA) protocol. Considering the impairments of satellite channels, we derive a lower bound of system performance, serving as a fast tool for initial evaluation of network behavior. Additionally, we identify the trade-offs inherent to the network design parameters, with a focus on packet loss rate and energy efficiency. Notably, in the visibility of only one extra satellite as receiver yields significant gains in overall system performance.

翻译：随着从5G向6G的演进，物联网设备数量预计将大幅增长，从而在各种应用中实现无缝且泛在的连接。为适应这一激增需求并满足高容量要求，必须整合非地面网络。然而，与地面接收器相比，卫星的广阔覆盖范围将导致大量用户同时尝试接入信道，从而增加碰撞概率。与此同时，巨型星座的部署使得地面用户可能同时处于多颗卫星的可见范围内，从而实现接收分集。因此，本文评估了在物联网节点遵循非正交多址接入-不规则重复时隙ALOHA协议共享信道的场景中多接收器的影响。考虑到卫星信道的损伤，我们推导了系统性能的下界，作为网络行为初步评估的快速工具。此外，我们明确了网络设计参数固有的权衡关系，重点关注丢包率和能量效率。值得注意的是，仅增加一颗可见卫星作为接收器即可显著提升整体系统性能。