Thank you for the opportunity to help you with your question!
"garbage bands" with frequencies of 900 MHz, 6 GHZ, and 2.4 GHZ were used in different equipment. These equipment used radio frequency as energy to warm food, and other purposes other than communication. However, the Federal Communications Commission introduced these "garbage bands" in the communication sector. The FCC used these radio frequency energy on devices that could use the bands (originally used in the army). the radio frequency energy communications idea gave rise to the invention of wifi. However, there is a long history concerning the invention of wifi after FCC brought the idea of wireless communications.
Please let me know if you need any clarification. I'm always happy to answer your questions.