  The growing low-Earth orbit (LEO) satellite constellations have become an
essential part of the fifth-generation (5G) non-terrestrial network (NTN)
market. These satellites can enable direct-to-cell connectivity for mobile
devices and support various applications with ubiquitous coverage for 5G and
beyond networks. However, satellite-based NTNs bring several challenges to the
5G handover protocol design. The high mobility of satellites can lead to
signaling storms and security compromises during handovers. This paper
addresses these challenges by proposing a secure and efficient group handover
protocol. The protocol's effectiveness is evaluated on a custom discrete-event
simulator and compared against the baseline 5G handover scheme. The simulator
is made publicly available.
