I. INTRODUCTION  
A. Contributions of the Study  
B. Survey Structure  

II. CONVENTIONAL DIGITAL-BASED DELIVERY  
A. Overview  
B. Critical Issues on Quality  

III. SOFTCAST: A PIONEER WORK ON SOFT DELIVERY  
A. Overview  

IV. TECHNICAL SOLUTIONS FOR SOFT DELIVERY  
A. Energy Compaction of Source Signals  
B. Channel-Aware and Perception-Aware Power Allocation  
C. Bandwidth Utilization  
D. Packet Loss Resilience  
E. Overhead Reduction  
F. Antenna and Resolution Heterogeneity  
G. Implementation  

V. EXTENSION FOR IMMERSIVE CONTENTS  

VI. FUTURE DIRECTIONS  
A. Hybrid Digital–Analog Delivery  
B. Applied Deep Neural Network  

VII. CONCLUSION