Embodiments of the present disclosure relate to defining and using unlicensed band, or sub-band, combinations for Carrier Aggregation (CA) for a wireless communication system that utilizes a standalone unlicensed technology (e.g., MulteFire or Fifth Generation (5G) New Radio (NR)). In general, a wireless device is configured with a CA combination that includes a Primary Cell (PCell) in a non-Dynamic Frequency Selection (DFS) spectrum and one or more Secondary Cells (SCells), at least one of which is in a DFS spectrum. In this manner, standalone operation in unlicensed spectrum utilizing DFS spectrum is provided.