SPACERTC: Unleashing the Low-latency Potential of Mega-constellations for Real-Time Communications¶
ABSTRACT¶
User-perceived latency is important for the quality of experience (QoE) of wide-area real-time communications (RTC). This paper explores a futuristic yet important problem facing the RTC community: can we exploit emerging mega-constellations to facilitate low-latency RTC globally? We carry out our quest in three steps.
用户感知延迟对于宽域实时通信（RTC）的体验质量（QoE）至关重要。本文探讨了RTC社区面临的一个未来重要问题：我们能否利用新兴的巨型卫星星座来实现全球低延迟的RTC？我们通过三步来展开这一探索：
First, through a measurement study associated with a large number of geo-distributed RTC users, we quantitatively expose that the meandering routes in the client-cloud and intercloud-site segment of existing cloud-based RTC architecture are critical culprits for the high latency issue suffered by wide-area RTC sessions. Second, we propose SPACE RTC, a satellite-cloud cooperative framework that adaptively selects relay servers upon satellites and cloud sites to build an overlay network which enables diverse close-to-optimal paths, and then judiciously allocates RTC flows upon the network to facilitate low-latency interactions. Finally, we implement our SPACE RTC prototype on an experimental environment based on public constellation information and RTC trace, and extensive experiments demonstrate that SPACE RTC can deliver near-optimal interactive latency, with up to 64.9% latency reduction as compared to other state-of-the-art cloudbased solutions under representative videoconferencing traffic.
首先，通过对大量地理分布的RTC用户进行测量研究，我们定量揭示了现有云端RTC架构中，客户端到云端以及云端间的传输路径曲折性是导致宽域RTC会话高延迟的关键因素。
其次，我们提出了SPACE RTC，一个卫星-云协同框架，该框架根据动态选取卫星和云站点中的中继服务器，构建一个叠加网络，提供多样化的近似最优路径，并智能地分配RTC流量，从而促进低延迟的交互。
最后，我们基于公共卫星星座信息和RTC流量数据，在实验环境中实现了SPACE RTC原型，并通过大量实验验证，SPACE RTC能够提供接近最优的交互延迟，与其他先进的基于云的解决方案相比，在代表性的视频会议流量下，能够实现高达64.9%的延迟减少。
TL;DR
现有的RTC不完全满意，原因是：云服务器的分布 + 路径曲折
提出的SpaceRTC：
- 动态选择 卫星和云服务器 的中继，构建立体的叠加网络
- 智能分配RTC流量