FDD+TDD downlink carrier aggregation characteristics, which of the following statements are correct? (Multiple choice)
A . If the TDD cell sets the frame offset, the FDD cell also needs to set the frame offset, and the FDD and TDD frame offset values are the same.
B . The TDD cell participating in carrier aggregation only supports the uplink and downlink subframe ratio SA4 or SA3.
C . Special subframe ratios are supported in addition to SSP4 and SSP5.
D . FDD carrier or TDD carrier can be used as PCC
Answer: AD