The three-volume set LNCS 12937 - 12939 constitutes the proceedings of the 16th International Conference on Wireless Algorithms, Systems, and Applications, WASA 2021, which was held during June 25-27, 2021. The conference took place in Nanjing, China.The 103 full and 57 short papers presented in these proceedings were carefully reviewed and selected from 315 submissions. The following topics are covered in Part I of the set: network protocols, signal processing, wireless telecommunication systems, blockchain, IoT and edge computing, artificial intelligence, computer security, distributed computer systems, machine learning, and others.