Frequency band defined in 3GPP can be classified into FDD frequency and TDD frequency as shown in Table 5.2-1 of TS 38.101-1
and TS38.101-2 . In case of TDD system, the same frequency is used for both UL and DL. However, in case of FDD system, UL frequency is different from DL frequency. Thus, when radio resource restriction scenario is discussed, care should be taken by considering these variations e.g. frequency used for both DL/ UL, UL only or DL only.
In addition, 5G system introduces further flexibility in using frequency band. For example, SUL (Supplementary UL) and SDL (Supplementary DL) are frequency band either defined only in DL or only in UL, as described in annex B of TS 38.300
. This spectrum is used to assist other frequency band, e.g. when base frequency band lacks coverage in either DL or UL, then SUL or SDL can be used to replace the base frequency band. If the SUL and/or SDL band is restricted for a certain network slice, some UEs may experience reduced coverage for the network slice.
Aspects related to carrier aggregation also needs to be considered similarly, because it is used to support QoS requirement by using different combination of DL bands and UL bands, e.g. using three DL bands together with one UL bands to boost downlink data rate. If allowed network slices differs for different frequency bands, then operation of CA also needs to take this into account for a network slice.
DSS (Dynamic Spectrum Sharing) allows use of same frequency band for both NR and E-UTRA, to cater for various deployment scenario of operators. Thus, same frequency band is split in time to support both E-UTRA and NR. Thus, when there is active restriction for a RAT in using a frequency, consideration should be given in which case it is restricted and any potential impact on quality of service.