This book constitutes the refereed post-conference proceedings of the 16th International Conference on Cognitive Radio Oriented Wireless Networks, CROWNCOM 2021, held in December 2021, and the 14th International Conference on Wireless Internet, WiCON 2021, held in November 2021. Due to COVID-19 pandemic the conferences were held virtually. The 18 full papers of CROWNCOM 2021 were selected from 40 submissions and present new research results and perspectives of cognitive radio systems for 5G and beyond 5G networks, big data technologies, such as storage, search and management. WiCON 2021 presents 7 papers covering topics ranging from technology issues to new applications and test-bed developments, especially focusing on next-generation wireless Internet, 5G, 6G, IoT, Industrial IoT, Healthcare IoT, and related methodologies.