In 5G networks, the gNodeB (gNB) communicates the MIMO configuration to User Equipment (UE) through control signals, particularly focusing on how the UE should handle multiple antenna transmissions. Here's how the notification mechanism works:

• Downlink Control Information (DCI): The gNB utilizes the Physical Downlink Control Channel (PDCCH) to send DCI, which includes details on resource allocation, power settings, and MIMO configurations such as the precoding matrix and number of spatial layers.
• Precoding Matrix Indicator (PMI): Included in DCI, the PMI directs the UE on the precoding matrix selected by the gNB, essential for beamforming and signal optimization.
• Rank Indicator (RI): This indicator, also part of DCI, informs the UE of the number of data streams the channel can support, enhancing spatial multiplexing efficiency.
• Channel State Information (CSI) Reporting: The UE reports back to the gNB on the channel conditions through CSI, including Channel Quality Indicator (CQI), PMI, and RI, allowing for dynamic adjustments in MIMO settings.
• Scheduling Requests and Adaptation: Based on CSI feedback, the gNB adjusts the scheduling and MIMO parameters to optimize network performance for both downlink and uplink.

This structured signaling and feedback mechanism enables the gNB to effectively manage MIMO configurations, ensuring the 5G network remains adaptive and optimized for all users.

Further Readings

• DL MIMO Configuration
• UL MIMO Configuration