Systems, methods, and circuitries are disclosed for determining Precoding Resource Block Groups (PRGs). In one example, a processor of a base station (BS) is configured to determine a plurality of PRGs that includes a number N consecutive Physical Resource Blocks (PRBs) over which a same precoder assignment is used, starting from a reference PRB. The plurality PRGs include a first boundary PRG, a second boundary PRG, and one or more other PRGs. The first boundary PRG is located at an upper boundary of a bandwidth part. The first boundary PRG comprises fewer than N PRBs when the upper boundary of the bandwidth part is not aligned with a PRG boundary. The second boundary PRG comprises fewer than N PRBs when a lower boundary of the bandwidth part is not aligned with a PRG boundary. A downlink data channel is transmitted to a UE in accordance with the precoder assignments.