# US 12,114,365 B2 · User apparatus, base station and communication system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,114,365 B2 - Document ID: US12114365B2 - Status: Granted - Kind: B2 - Application number: 18/163,582 - Filed: 2023-02-02 - Published: 2023-06-08 - Granted: 2024-10-08 - Earliest claimed: 2018-08-07 - Assignees: Mitsubishi Electric Corporation - Applicants: Mitsubishi Electric Corporation - Inventors: Mitsuru Mochizuki; Tadahiro Shimoda; Noriyuki Fukui; Daichi Uchino - Web page: https://patentgrep.com/patent/US12114365B2 ## CPC - H04W 76/34: Selective release of ongoing connections - H04W 56/0015: {one node acting as a reference for the others} - H04W 56/0045: {compensating for timing error by altering transmission time} - H04W 74/006: {in the downlink, i.e. towards the terminal} - H04W 74/0833: Random access procedures, e.g. with 4-step access - H04W 36/0069: {in case of dual connectivity, e.g. decoupled uplink/downlink} - H04W 74/0838: using contention-free random access [CFRA] - H04W 76/14: Direct-mode setup - H04W 76/15: Setup of multiple wireless link connections - H04W 76/19: Connection re-establishment - H04W 88/06: adapted for operation in multiple networks {or having at least two operational modes}, e.g. multi-mode terminals - H04W 88/085: {Access point devices with remote components} - Y02D 30/70: in wireless communication networks - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE ## Abstract A radio communication technology for enabling high reliability, a high transmission rate, and low power consumption is provided. A communication system includes a communication terminal and a base station. The base station includes a plurality of transmitter-receivers configured to perform radio communication with the communication terminal. The base station is configured to perform radio communication with the communication terminal by using a part or all of the plurality of transmitter-receivers. The communication terminal receives a downlink synchronization signal from at least one first transmitter-receiver to be newly connected, and establishes downlink synchronization with the at least one first transmitter-receiver by using the downlink synchronization signal. The communication terminal establishes uplink synchronization with the at least one first transmitter-receiver through random access processing. ## Claims ### Claim 1 A user apparatus in a communication system comprising the user apparatus; and a plurality of base stations configured to wirelessly communicate with the user apparatus, the user apparatus comprising: a processor communicating with the plurality of base stations, wherein the plurality of base stations include a master node and a secondary node that support dual connectivity for the user apparatus, the processor of the user apparatus receives from the master node Radio Resource Control (RRC) signaling including information related to usage of a split Signal Radio Bearer (SRB) or usage of an SRB3 in a procedure for adding or modifying the secondary node, the processor of the user apparatus determines which of the split SRB and the SRB3 is configured, in a case in which the split SRB is configured in a state of Master Cell Group (MCG) failure, the processor of the user apparatus transmits information related to the MCG failure to the master node via the secondary node using the split SRB, and receives an RRC Reconfiguration using the split SRB from the master node via the secondary node and in a case in which the split SRB is not configured and the SRB3 is configured in a state of the MCG failure, the processor of the user apparatus transmits the information related to the MCG failure to the secondary node using the SRB3, and receives an RRC Reconfiguration from the secondary node using the SRB3. ### Claim 2 (depends on 1) The user apparatus according to claim 1, wherein the processor of the user apparatus receives an RRC Release transmitted using the split SRB from the master node via the secondary node. ### Claim 3 (depends on 1) The user apparatus according to claim 1, wherein the secondary node transmits a request for releasing the secondary node to the master node. ### Claim 4 (depends on 1) The user apparatus according to claim 1, wherein the processor of the user apparatus transmits a response for the RRC Reconfiguration to the secondary node. ### Claim 5 (depends on 1) The user apparatus according to claim 1, wherein the processor of the user apparatus performs configuration related to change of a role of the master node and the secondary node, using the received RRC Reconfiguration. ### Claim 6 A base station in a communication system comprising a user apparatus; and a plurality of base stations configured to wirelessly communicate with the user apparatus, the base station comprising: a processor communicating with the user apparatus, wherein the plurality of base stations include a master node and a secondary node that support dual connectivity for the user apparatus, the processor of the base station operates the base station as the secondary node, the processor of the base station transmits to the user apparatus Radio Resource Control (RRC) signaling including information related to usage of a split Signal Radio Bearer (SRB) or usage of an SRB3 in a procedure for adding or modifying the secondary node, the processor of the user apparatus determines which of the split SRB and the SRB3 is configured, in a case in which the split SRB is configured in a state of Master Cell Group (MCG) failure, the processor of the base station receives from the user apparatus information related to the MCG failure using the split SRB, transmits the information related to the MCG failure using the split SRB to the master node, receives an RRC Reconfiguration from the master node using the split SRB, and transmits to the user apparatus the RRC Reconfiguration using the split SRB, and in a case in which the split SRB is not configured and the SRB3 is configured in a state of the MCG failure, the processor of the base station receives the information related to the MCG failure from the user apparatus using the SRB3, and transmits an RRC Reconfiguration to the user apparatus using the SRB3. ### Claim 7 A communication system comprising a user apparatus; and a plurality of base stations configured to wirelessly communicate with the user apparatus, the user apparatus comprising: a processor communicating with the plurality of base stations, wherein the plurality of base stations include a master node and a secondary node that support dual connectivity for the user apparatus, the processor of the user apparatus receives from the master node Radio Resource Control (RRC) signaling including information related to usage of a split Signal Radio Bearer (SRB) or usage of an SRB3 in a procedure for adding or modifying the secondary node, the processor of the user apparatus determines which of the split SRB and the SRB3 is configured, in a case in which the split SRB is configured in a state of Master Cell Group (MCG) failure, the processor of the user apparatus transmits information related to the MCG failure to the master node via the secondary node using the split SRB, and receives an RRC Reconfiguration using the split SRB from the master node via the secondary node, and in a case in which the split SRB is not configured and the SRB3 is configured in a state of the MCG failure, the processor of the user apparatus transmits the information related to the MCG failure to the secondary node using the SRB3, and receives an RRC Reconfiguration from the secondary node using the SRB3.