I. INTRODUCTION  
II. AN OVERVIEW OF 6G TECHNOLOGIES  
III. ARTIFICIAL INTELLIGENCE  
IV. INTELLIGENT SURFACES  
V. INDEX MODULATION  
VI. SIMULTANEOUS WIRELESS INFORMATION AND POWER TRANSFER (SWIPT)  
VII. SPACE-AIR-GROUND-SEA INTEGRATED NETWORK  
VIII. OTHER POTENTIAL TECHNOLOGIES  
IX. SECURITY AND PRIVACY  
X. APPLICATIONS  
XI. CONCLUSION