Question: For a UE with 2 receiver antenna ports, what is the support requirement for receivers with enhanced inter-stream interference suppression for SU-MIMO PDSCH with rank 2?
Option 1: Mandatory for all UEs to ensure basic performance
Option 2: Conditional, based on the network's MIMO configuration
Option 3: Not applicable to UEs with less than 4 receiver antenna ports
Option 4: Optional, as specified in enhanced performance requirements
Explanation: The correct answer is Option 4 because it is optional for User Equipment (UE) with 2 receiver antenna ports to support receivers with enhanced inter-stream interference suppression specifically for Single-user MIMO (SU-MIMO) Physical Downlink Shared Channel (PDSCH) transmissions with a rank of 2, allowing variability in UE design and capability.