A system and method for managing utilization of un-licensed frequency spectrum resources for secondary systems, a system and a method for the system, and a non-transitory computer-readable medium including computer-readable instructions. The system for managing utilization of un-licensed frequency spectrum resources for secondary systems includes: circuitry, configured to assign a first un-licensed frequency spectrum resource in an availability time period to a first secondary system and reassign at least part of the first un-licensed frequency spectrum resource during the availability time period based on current resource utilization, wherein the circuitry is configured to assign and reassign the first un-licensed frequency spectrum resource under protection of a primary system which is licensed with the un-licensed frequency spectrum resources.