I. INTRODUCTION
A. Existing Surveys and Reviews
B. Motivation and Contributions
C. Literature Review Protocol and Organization
II. CHARACTERIZING THE NSIN AND USE CASES
A. Review of Network Definitions
B. Segments of NSIN
C. Differences between a HAP and a UAV
D. Design Consideration of NSIN
E. Promising Use Cases of NSIN
F. Summary and Lessons Learned
III. CHANNEL MODELING OF NSIN
A. Problems Encountered in Experiments
B. Phase Delay
C. Large-Scale Fading
D. Small-Scale Fading
E. Existing Channel Models of NSIN
F. Summary and Lessons Learned
IV. NETWORKING OF NSIN
A. Problems Encountered in Experiments
B. Deployment of NSIN
C. Handoff Management
D. Network Management
E. Summary and Lessons Learned
V. TRANSMISSION VIA NSIN
A. Problems Encountered in Experiments
B. Active beam forming
C. Passive beam forming
D. Multi-connectivity
F. Summary and Lessons Learned
VI. OPEN ISSUES AND PROMISING DIRECTIONS
A. Generalized Channel Model
B. Quantum Communication-Empowered NSIN
C. Exploration of All Frequency Spectra
D. Generative AI-Empowered Large-Scale NSIN
VII. CONCLUSION