For MIMO, the UE power consumption mainly depends on how many RF chains and antennas are used for transmitting/receiving. From a network perspective, it is better that the UE always uses its full capability to transmit and receive signals in case of the arrival of a burst of data. On the other hand, since the gNB is not aware of the UE power status or UE characteristics (e.g., the UE temperature), the gNB doesn’t know when to allow the UE to use a lower MIMO capability to help the UE to save power. Therefore the UE can report its desired maximum number of layers and/or desired number of antennas in UE assistance information. Note that the UE desired maximum number of layers is already agreed to be reported for the purpose of overheating issue, which can easily be extended to the power saving purpose.