Content for  TR 38.844  Word version:  18.0.0

The network only configures channel bandwidth according to UE capabilities. RAN4 requirements do not cover the case when a UE is configured with a channel that is not contained within a specified band. Thus, if the network were to configure the UE channel bandwidth beyond the band edge, then the UE behavior would be unknown. However, one approach to avoid the unexpected UE behavior is for the NW to ensure that the UE CBW filter will not exceed the NR band edges. This can be achieved as long as the wider CBW is not wider than the NR band. The NW can control the UE CBW filter location near band edges by setting the CRB0 location (within RIV locationAndBandwidth) and carrierBandwidth. Then the NW can set BWP to utilize the RBs aligned to the left or right edge of the UE carrier bandwidth using N_BWP^size, etc. In this manner there is no need or the NW to schedule the UE CBW filter outside the NR band edge, potentially leading to unknown UE behaviour. Further channel filter configuration examples can be seen in clause 6.1.3 which show how the NW can avoid setting the UE CBW filter outside the band edge. For the FDD case with a 7 MHz irregular block at the band edge, the arrangement in Figure 6.1.2.1.2-1 can be modified by shifting the DL carrier grid corresponding to the 15 MHz CHBW upwards by n*900 MHz (5 PRB) as shown in Figure 6.1.2.3-1 such that the 15 MHz CHBW is within the band range thus increasing the BS duplex spacing between the UL and DL carriers while maintaining PRB alignment and the default duplex spacing for the 2 x 5 MHz UE-specific bandwidths and the BWP#0. The default duplex spacing is not specified for the BS (cell) bandwidth and the SIB1 procedure for initial attach is separate for the UL and DL.

For the TDD case illustrated in Figure 6.1.2.3-2 with a 55 MHz irregular block at the band edge, a common center frequency for all CHBW and BWP can be maintained but with the bandwidths adjusted to optimize the transmission bandwidth configuration of the irregular block (PRBs not blanked) as shown in Figure 6.1.2.3-2. The additional BWP#1 configured for UEs supporting asymmetric bandwidth and the irregular channel bandwidth is also centred with the PRBs at the upper edge blanked. Legacy UEs are configured with the BWP#0 or any other BWP within the 40 MHz block, each additional BWP with common center frequency.