To accommodate the increasing communication needs in non-terrestrial networks (NTNs), wireless users in remote areas may require access to more spectrum than is currently allocated. Terrestrial networks (TNs), such as cellular networks, are deployed in specific areas, but many underused licensed spectrum bands remain in remote areas. Therefore, bringing NTNs to a shared spectrum with TNs can improve network capacity under reasonable interference management. However, in satellite-terrestrial integrated networks (STINs), the comprehensive coverage of a satellite and the unbalanced communication resources of STINs make it challenging to effectively manage mutual interference between NTN and TN. This article presents the fundamentals and prospects of spectrum sharing (SS) in STINs by introducing four SS frameworks, their potential application scenarios, and technical challenges. Furthermore, advanced SS approaches related to interference management in STINs and performance metrics of SS in STINs are introduced. Moreover, a preliminary performance evaluation showcases the potential for sharing the spectrum between NTN and TN. Finally, future research opportunities for SS in STINs are discussed.

翻译：为满足非地面网络日益增长的通信需求，偏远地区的无线用户可能需要获取比当前分配更多的频谱资源。地面网络（如蜂窝网络）部署于特定区域，但偏远地区仍存在大量未充分利用的授权频谱。因此，在合理干扰管理下，使非地面网络与地面网络共享频谱可提升网络容量。然而，在卫星-地面一体化网络中，卫星的广域覆盖特性与网络通信资源的不均衡分布，使得有效管理非地面网络与地面网络间的相互干扰面临挑战。本文通过介绍四种频谱共享框架、潜在应用场景与技术挑战，系统阐述卫星-地面一体化网络中频谱共享的基础原理与发展前景。进一步，文章介绍了与干扰管理相关的先进频谱共享方法及性能评估指标。此外，通过初步性能评估展示了非地面网络与地面网络间频谱共享的潜力。最后，探讨了卫星-地面一体化网络中频谱共享的未来研究方向。