15.5.1.5 Load reporting for inter-system load balancing

The load reporting function for inter-system load balancing is executed by exchanging load information between NG-RAN and E-UTRAN. Both event-triggered and periodic inter-system load reporting are supported. Event-triggered inter-system load reports are sent when the reporting node detects crossing of cell load thresholds.

The following load related information should be supported:

• Cell Capacity Class value (UL/DL relative capacity indicator);
• Capacity value (per cell: UL/DL available capacity);
• RRC connections (number of RRC connections, and available RRC Connection Capacity);
• Number of active UEs;
• Radio Resource Status (per cell PRB usage: UL/DL GBR PRB usage for MIMO, DL/UL non-GBR PRB usage for MIMO, DL/UL total PRB usage for MIMO).

NGAP procedures used for inter-system load balancing are Uplink RAN Configuration Transfer and Downlink RAN Configuration Transfer.

S1AP procedures used for inter-system load balancing are eNB Configuration Transfer and MME Configuration Transfer.