STAR FRONT: Cooperatively Constructing Pervasive and Low-Latency CDNs Upon Emerging LEO Satellites and Clouds

Abstract

Internet content providers (ICPs) typically exploit content distribution networks (CDNs) to provide wide-area data access with high availability and low latency. However, our analysis on a large-scale trace collected from seven major CDN operators has revealed that: from a global perspective, there are still a large portion of users suffering from high userperceived latency due to the insufficient deployment of terrestrial cloud infrastructures, especially in remote or rural areas where even the closest available cache server is too far away. This paper presents STAR FRONT, a cost-effective content distribution framework to optimize global CDNs and enable low content access latency anywhere. STAR FRONT collaboratively builds CDNs upon emerging low earth orbit (LEO) constellations and existing cloud platforms to satisfy the low latency requirements while minimizing the operational cost. Specifically, STAR FRONT exploits a key insight that emerging mega-constellations will consist of thousands of LEO satellites which can be equipped with high-speed data links and storage, and thus can potentially work as “cache in space” to enable pervasive and low-latency data access. STAR FRONT judiciously places replicas on either LEO satellite caches or terrestrial cloud caches, and dynamically assigns user requests to proper cache servers based on different constellation parameters, cloud/user distributions and pricing policies. We have implemented a STAR FRONT prototype in our testbed, and extensive trace-driven evaluations covering multiple geodistributed vantage points have demonstrated that STAR FRONT can effectively reduce the global content access latency with acceptable operational cost under representative CDN traffic.

互联网内容提供商（ICP）通常利用内容分发网络（CDN）来提供具有高可用性和低延迟的广域数据访问。然而，我们对从七个主要CDN运营商收集的大规模跟踪数据的分析表明：从全球角度来看，由于地面云基础设施部署不足，仍然有很大一部分用户遭受较高的用户感知延迟，尤其是在偏远或农村地区，即使是最近的可用缓存服务器也太远。

本文介绍了一种经济高效的内容分发框架STAR FRONT，旨在优化全球CDN并实现任何地方的低内容访问延迟。STAR FRONT 协同构建于新兴的低地球轨道（LEO）卫星星座和现有云平台之上 ，以满足低延迟要求，同时最大限度地降低运营成本。

具体来说，STAR FRONT利用了一个关键的洞察力，即 新兴的巨型星座将由数千颗LEO卫星组成，这些卫星可以配备高速数据链路和存储，因此可以作为“太空缓存” 来支持普遍的低延迟数据访问。STAR FRONT明智地 将副本放置在LEO卫星缓存或地面云缓存上 ，并根据不同的星座参数、云/用户分布和定价策略，动态地将用户请求分配给适当的缓存服务器。

我们已经在我们的测试平台中实现了STAR FRONT原型，并且涵盖多个地理分布有利位置的大量跟踪驱动评估表明，在具有代表性的CDN流量下，STAR FRONT可以有效地降低全局内容访问延迟，并具有可接受的运营成本。