Section: 4 Frame structure
Content: Throughout this specification, unless otherwise noted, the size of various fields in the time domain is expressed as a number of time units seconds. Downlink, uplink and sidelink transmissions are organized into radio frames with duration. Three radio frame structures are supported: - Type 1, applicable to FDD only, - Type 2, applicable to TDD only, - Type 3, applicable to LAA secondary cell operation only. NOTE: LAA secondary cell operation only applies to frame structure type 3. Transmissions in multiple cells can be aggregated where up to 31 secondary cells can be used in addition to the primary cell. Unless otherwise noted, the description in this specification applies to each of the up to 32 serving cells. In case of multi-cell aggregation, different frame structures can be used in the different serving cells.