In some implementations, the SgNB 2 may receive a radio bearer setup request from the MeNB 1, and select at least one dedicated numerology according to requirements for an NR Data Radio Bearer (DRB) for the UE 3 indicated by the radio bearer setup request. The radio bearer setup request is a message for causing the gNB 2 to configure an NR DRB for E-UTRA-NR DC. This radio bearer setup request may be referred to as an SgNB Addition Request. The requirements for an NR DRB may include one or both of QoS requirements and a service type. The QoS requirements include at least one of: a priority required for an NR DRB, or for a network bearer or a flow associated with the NR DRB; a Maximum Bit Rate (MBR); and an Allocation and Retention Priority (ARP). The service type indicates, for example, one of enhanced Mobile Broad Band (eMBB), Ultra Reliable and Low Latency Communication (URLLC), and massive Machine Type Communication (mMTC).

The SgNB 2 may include in the NR radio resource configuration an information element indicating the selected at least one dedicated numerology. In this case, the SgNB 2 may send the NR radio resource configuration, which explicitly or implicitly indicates the selected at least one numerology, to the MeNB 1 using a response message (e.g., an SgNB Addition Request Acknowledge message) in response to the radio bearer setup request. The MeNB 1 may transmit the NR radio resource configuration received from the SgNB 2 to the UE 3 using an RRC Connection Reconfiguration message.