1 INTRODUCTION

2 OVERVIEW AND FUNDAMENTALS OF FEDERATED LEARNING  
2.1 Overview of Federated Learning  
2.2 Privacy Threats to Federated Learning  

3 TECHNIQUES FOR PRIVACY-PRESERVING AGGREGATION

4 PRIVACY-PRESERVING AGGREGATION PROTOCOLS IN FEDERATED LEARNING

5 FEDERATED LEARNING FRAMEWORKS FOR PRIVACY-PRESERVING AGGREGATION

6 CHALLENGES AND FUTURE DIRECTIONS  
6.1 Throughput Improvement  
6.2 Hybrid Schemes for Stronger Security  

7 CONCLUSIONS