Integrated Communication and Navigation Enabled Low Earth Orbit Satellite Systems

Relying on the powerful communication capabilities, rapidly changing geometric configuration, and strong power, Low Earth Orbit (LEO) satellites own the potential to offer the integrated communication and navigation (ICAN) services with broader coverage, higher precision, and stronger reliability. Against this backdrop, LEO-ICAN has been attracting wide research attention. However, despite the above promising potential, many challenges are still unresolved in terms of architecture, key technologies and unified performance characterization. Therefore, in this article, we first elaborate three evolutionary stages of LEO-ICAN, where a fusional LEO-ICAN architecture is innovatively proposed to better meet the high-speed communication and high-precision navigation requirements of the emerging applications. Moreover, key technologies are discussed, and a use case referring to the joint optimization in fusional LEO-ICAN systems is studied, where we jointly optimize the satellite selection and beamforming design to simultaneously balancing the communication and navigation performance. Effectiveness of our proposed scheme is proved through extensive simulations. In addition, a performance evaluation index for LEO-ICAN systems is established based on the minimum variance unbiased estimate (MVUE), providing theoretical guidance and support for the improvement of both communication and navigation performance. Finally, open issues and future research directions are discussed.