The power saving schemes with UE ad

The power saving schemes with UE adaptation to the number of MIMO layers are to allow UE to suspend some RF chains. When the MIMO channels have low rank with receiver observed mutually dependent among receive antenna chain, UE still has to turn on the receiver chains of the RF and baseband processing of all antenna. The mutual information from the MIMO channel is very low. The MIMO decoding performance degrades with the low rank MIMO channel even the RF and baseband processing chains of all antenna remains on. The power saving schemes with UE adaptation to the number of MIMO layers allow UE to suspend the subset of RF processing chains during low-rank MIMO channel.

The bottleneck of the current DCI based BWP switching is the PDSCH reception performance in the large BWP upon BWP switching. As the bandwidth difference between the small BWP and the large BWP can be very different, the channel large-scale parameters and the CSI acquired in the small BWP may not be identical to the large BWP, especially when the channel is frequency-selective. Hence to guarantee the performance of the PDSCH reception in the large BWP, a simple but efficient solution is to trigger aperiodic CSI-RS for channel tracking or CSI reporting for target BWP in BWP switch as shown in Fig. 2. The aperiodic CSI-RS can locate just before the PDSCH of the target BWP and guarantee sufficient time for UE calculation of the channel parameters. Note that for this mechanism, UE still just processes one BWP at a given time.