Systems and methods for dual-connectivity operation

A user equipment (UE) for receiving a radio resource control (RRC) message, comprising:

• a processor;
• and
• memory in electronic communication with the processor, wherein instructions stored in the memory are executable to:
• receive an RRC connection reconfiguration (RRCConnectionReconfiguration) message including secondary cell group (SCG) configuration parameters,
• wherein a master cell group (MCG) and a SCG are configured for dual connectivity, a first Medium Access Control (MAC) entity is mapped to the MCG, a second Medium Access Control (MAC) entity is mapped to the SCG, the RRC connection reconfiguration message is exchanged via the MCG, the MCG comprises at least a primary cell (PCell), and the SCG comprises at least a primary secondary cell (PSCell),
• wherein the RRC connection reconfiguration message has a structure to switch between a case that the SCG configuration parameters include a data radio bearer (DRB) configuration and a case that the SCG configuration parameters do not include a DRB configuration, wherein in the case that the SCG configuration parameters include a DRB configuration, a DRB corresponding to the DRB configuration is established to the SCG.

An evolved Node B (eNB) for sending a radio resource control (RRC) message, comprising:

• a processor;
• and
• memory in electronic communication with the processor, wherein instructions stored in the memory are executable to:
• send an RRC connection reconfiguration (RRCConnectionReconfiguration) message including secondary cell group (SCG) configuration parameters to a user equipment (UE),
• wherein a master cell group (MCG) and a SCG are configured for dual connectivity, a first Medium Access Control (MAC) entity is mapped to the MCG, a second Medium Access Control (MAC) entity is mapped to the SCG, the RRC connection reconfiguration message is exchanged via the MCG, the MCG comprises at least a primary cell (PCell), the SCG comprises at least a primary secondary cell (PSCell),
• wherein the RRC connection reconfiguration message has a structure to switch between a case that the SCG configuration parameters include a data radio bearer (DRB) configuration and a case that the SCG configuration parameters do not include a DRB configuration, wherein in the case that the SCG configuration parameters include a DRB configuration, a DRB corresponding to the DRB configuration is established to the SCG.