Low Earth orbit (LEO) satellites have been envisioned as a significant component of the sixth generation (6G) network architecture for achieving ubiquitous coverage and seamless access. However, the implementation of LEO satellites is largely restricted by the deployment of ground stations. Inter-satellite links (ISLs) have been regarded as a promising technique to fully exploit the potentials of LEO mega constellations by concatenating multiple satellites to constitute an autonomous space network. In this article, we present the merits of implementing ISLs in LEO mega constellations and the representative applications empowered/inspired by ISLs. Moreover, we outline several key technical challenges as well as potential solutions related to LEO satellite networks with ISLs, including performance analysis for system design, routing and load balancing, and resource allocation. Particularly, the potential of using ISLs in enhancing in-flight connectivity is showcased with a preliminary performance evaluation. Finally, some open issues are discussed to inspire future research.

翻译：低地球轨道（LEO）卫星已被视为第六代（6G）网络架构的重要组成部分，以实现无处不在的覆盖和无缝接入。然而，LEO卫星的实施在很大程度上受限于地面站的部署。星间链路（ISL）被认为是一种有前景的技术，通过连接多颗卫星构成自主的空间网络，从而充分发挥LEO巨型星座的潜力。本文阐述了在LEO巨型星座中部署ISL的优势，以及由ISL赋能或启发的代表性应用。此外，我们概述了与配备ISL的LEO卫星网络相关的若干关键技术挑战及潜在解决方案，包括系统设计的性能分析、路由与负载均衡以及资源分配。特别地，我们通过初步性能评估展示了利用ISL增强航空机载通信的潜力。最后，讨论了一些开放性问题以启发未来研究。