Method and apparatus for resume procedure for data transfer in RRC_INACTIVE state in mobile wireless communication system

A terminal in a wireless communication system, the terminal comprising:

• a transceiver configured to transmit and receive a signal;
• and
• a controller configured to control the transceiver to:
• receive from a base station a first Radio Resource Control (RRC) message, wherein the first RRC message comprises a set of parameters for RRC_INACTIVE state;
• store RRC configuration in User Equipment (UE) context, wherein the RRC configuration comprises a first security key and a second security key;
• transition to the RRC_INACTIVE state;
• receive from the base station a system information;
• determine to initiate a second resume procedure based on the set of parameters for the RRC_INACTIVE state and the system information;
• restore a first configuration from the UE context, wherein the first configuration comprises a Packet Data Convergence Protocol (PDCP) configuration and a bearer configuration;
• reestablish PDCP entity,
• transmit to the base station a second RRC message, wherein the second RRC message comprises a part of a Message Authentication Code, wherein the Message Authentication Code is calculated based on:
• the second security key;
• a cell identifier;
• and
• a terminal identifier;
• perform with the base station data transfer in the RRC INACTIVE state based on:
• a third security key;
• a fourth security key;
• and
• the first configuration;
• receive from the base station a third RRC message;
• and
• terminate the second resume procedure.

A method performed by a base station, the method comprising:

• transmitting to a terminal a first Radio Resource Control (RRC) message, wherein the first RRC message comprises a set of parameters for RRC_INACTIVE state, wherein the set of parameters for the RRC_INACTIVE state comprises a NextHopChanningCount (NCC);
• storing RRC configuration in User Equipment (UE) context, wherein the RRC configuration comprises a first security key and a second security key;
• receiving from the terminal a Medium Access Control (MAC) Protocol Data Unit (PDU), wherein the MAC PDU comprises a second RRC message and a Service Data Unit (SDU), wherein a predefined configuration is applied to the second RRC message, wherein the predefined configuration comprises Transparent Mode (TM) Radio Link Control (RLC) configuration, wherein a bearer configuration and a PDCP configuration restored from the UE context are applied to the SDU, wherein the second RRC message comprises a part of Message Authentication Code calculated based on:
• the second security key;
• a cell identifier;
• and
• a terminal identifier;
• and
• performing with the terminal data transfer in the RRC_INACTIVE state during a second resume procedure based on:
• a third security key;
• a fourth security key;
• the PDCP configuration;
• and
• the bearer configuration,
• wherein the third security key is derived from the first security key and the NCC,
• wherein the fourth security key is derived from the second security key and the NCC,
• wherein when the data transfer with the terminal in the RRC_INACTIVE state ends:
• the first security key and the second security key are deleted in the UE context;
• and
• the third security key and the fourth security key are stored in the UE context.