  Low Earth orbit (LEO) mega-constellation satellite networks have shown great
potential to extend the coverage capability of conventional terrestrial
networks. How to systematically define, quantify, and assess the technical
performance of LEO mega-constellation satellite networks remains an open issue.
In this paper, we propose a comprehensive key performance indicator (KPI)
framework for mega-constellation based LEO satellite networks. An efficient LEO
constellation oriented performance evaluation methodology is then carefully
designed by resorting to the concept of interfering area and spherical
geographic cell. We have carried out rigorous system-level simulations and
provided numerical results to assess the KPI framework. It can be observed that
the achieved area traffic capacity of the reference LEO constellation is around
4 Kbps/km2, with service availability ranging from 0.36 to 0.39. Besides, the
average access success probability and handover failure rate is approximate to
96% and 10%, respectively, in the nearest satellite association scheme.
