I. INTRODUCTION  
A. Existing Surveys and Tutorials  
B. Contributions and Organization  

II. SYSTEM MODEL  
A. Network Model  
B. Mathematical Model  

III. CLUSTERING OF SENSORS  
A. Clustering Algorithms  
B. Clustering of Sensors in UAV Assisted Data Collection  

IV. DATA COLLECTION MODE  

V. JOINT PATH PLANNING AND RESOURCE ALLOCATION  

VI. FUTURE TRENDS  
A. Efficient Multiple Access  
B. Joint Sensing and Data Collection  

VII. CONCLUSION