# US 10,375,606 B2 · Radio communication system, radio station, radio terminal, communication control method, and computer-readable medium > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,375,606 B2 - Document ID: US10375606B2 - Status: Granted - Kind: B2 - Application number: 14/655,984 - Filed: 2013-11-20 - Published: 2015-11-26 - Granted: 2019-08-06 - Earliest claimed: 2012-12-28 - Assignees: NEC Corporation - Applicants: NEC Corporation - Inventors: Hisashi Futaki; Hiroaki Aminaka - Web page: https://patentgrep.com/patent/US10375606B2 ## CPC - H04W 36/0016: {Hand-off preparation specially adapted for end-to-end data sessions} - H04W 36/0033: {with transfer of context information} - H04W 36/00692: {using simultaneous multiple data streams, e.g. cooperative multipoint [CoMP], carrier aggregation [CA] or multiple input multiple output [MIMO] (allocation of physical resources in CoMP or in CA H04L5/0035)} - H04W 36/087: {between radio units of access points} - H04W 76/20: Manipulation of established connections - H04W 76/28: Discontinuous transmission [DTX]; Discontinuous reception [DRX] - H04B 7/022: Site diversity; Macro-diversity (using two or more spaced independent antennas H04B7/04) - H04W 36/0235: {by transmitting sequence numbers, e.g. SN status transfer} - H04W 76/15: Setup of multiple wireless link connections - 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) - H04B: TRANSMISSION - 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 network (6) and a radio terminal (4) are configured to, when the radio terminal (4) is using a first cell (10) served by a first radio station (1) as a primary cell and a second cell (20) served by a second radio station (2) as a secondary cell, change the primary cell from the first cell (10) to a third cell (30) served by a third radio station (3) while keeping communication status information regarding the radio terminal (1) on the second cell (20). It is thus, for example, possible to enable a communication service in the secondary cell to be continued even after the primary cell is changed when the primary cell is changed during execution of carrier aggregation (e.g., Inter-eNB CA) on a plurality of cells served by different radio stations. ## Claims ### Claim 1 A radio communication system comprising: a radio network including a first radio station configured to operate a first cell, a second radio station configured to operate a second cell, and a third radio station configured to operate a third cell; and a radio terminal having a capability of Dual Connectivity using either the first cell or the third cell as a primary cell and the second cell as a secondary cell, wherein the first radio station is configured to, within a procedure changing a radio station operating the primary cell of the radio terminal from the first radio station to the third radio station, transmit a Radio Resource Control (RRC) Connection Reconfiguration message to trigger the radio terminal to: release configuration information on the second cell except for Data Radio Bearer (DRB) configuration information corresponding to a DRB established in the second cell; and re-configure the DRB established in the second cell. ### Claim 2 (depends on 1) The radio communication system according to claim 1, wherein the RRC Connection Reconfiguration message is further configured to trigger the radio terminal to re-configure the DRB, which had been established in the second cell, to a DRB in the third cell as the primary cell. ### Claim 3 (depends on 1) The radio communication system according to claim 1, wherein the DRB configuration information is not released within the procedure changing the radio station operating the primary cell of the radio terminal from the first radio station to the third radio station. ### Claim 4 (depends on 1) The radio communication system according to claim 1, wherein the first radio station is configured to receive communication status information on the second cell from the second radio station and to send at least the communication status information to the third radio station. ### Claim 5 (depends on 1) The radio communication system according to claim 1, wherein the third radio station is configured to receive communication status information on the second cell from the second radio station. ### Claim 6 (depends on 1) The radio communication system according to claim 1, wherein the third radio station is configured to allow data communication which has been provided in the second cell to be continuously provided in the third cell after the radio station operating the primary cell is changed from the first radio station to the third radio station. ### Claim 7 (depends on 1) The radio communication system according to claim 1, wherein the second radio station and the radio terminal are configured to suspend data communication which has been provided to the radio terminal in the second cell while the radio station operating the primary cell is being changed from the first radio station to the third radio station and configured to resume the data communication, which has been provided in the second cell, in the second cell after the radio station operating the primary cell is changed from the first radio station to the third radio station. ### Claim 8 (depends on 4) The radio communication system according to claim 4, wherein the communication status information includes at least one of a user data transmission status, a user data reception status, service information, bearer information, and radio resource configuration information. ### Claim 9 (depends on 8) The radio communication system according to claim 8, wherein the user data transmission status and the user data reception status include at least one of a Packet Data Convergence Protocol (PDCP) Sequence Number (SN), an Evolved Universal Terrestrial Access Network (E-UTRAN) Radio Access Bearer (E-RAB) Identity (ID), a Receive Status of uplink (UL) PDCP service data units (SDUs), an UL COUNT Value (PDCP SN+Hyper Frame Number (HFN)), a Downlink (DL) COUNT Value (PDCP SN+HFN), and a Radio Link Control (RLC) STATUS. ### Claim 10 (depends on 4) The radio communication system according to claim 4, wherein at least one of the first radio station and the third radio station is configured to request the second radio station to report the communication status information, and the second radio station is configured to report the communication status information to the first radio station or the third radio station. ### Claim 11 (depends on 1) The radio communication system according to claim 1, wherein the first radio station is configured to request the second radio station to abort or suspend data communication with the radio terminal in the second cell, and the second radio station is configured to abort or suspend the data communication with the radio terminal in the second cell. ### Claim 12 (depends on 1) The radio communication system according to claim 1, wherein the radio network further includes an upper-level network device, at least one of the first radio station and the second radio station is configured to request the upper-level network device to switch a bearer, configured in the second radio station for the radio terminal, to the first radio station, and the upper-level network device is configured to switch the bearer for the radio terminal to the first radio station. ### Claim 13 (depends on 1) The radio communication system according to claim 1, wherein at least one of the first radio station and the third radio station is configured to request the second radio station to resume communication with the radio terminal in the second cell, and the second radio station is configured to resume the communication with the radio terminal in the second cell. ### Claim 14 A first radio station configured to operate a first cell, the first radio station comprising: a transceiver; and at least one processor configured to, via the transceiver, communicate with a radio terminal capable of performing Dual Connectivity using either the first cell or a third cell of a third radio station as a primary cell and a second cell of a second radio station as a secondary cell, wherein the at least one processor is further configured to, within a procedure changing a radio station operating the primary cell of the radio terminal from the first radio station to the third radio station, transmit a Radio Resource Control (RRC) Connection Reconfiguration message to trigger the radio terminal to: release configuration information on the second cell except for Data Radio Bearer (DRB) configuration information corresponding to a DRB established in the second cell; and re-configure the DRB established in the second cell. ### Claim 15 (depends on 14) The first radio station according to claim 14, wherein the RRC Connection Reconfiguration message is further configured to trigger the radio terminal to re-configure the DRB, which had been established in the second cell, to a DRB in the third cell as the primary cell. ### Claim 16 (depends on 14) The first radio station according to claim 14, wherein the at least one processor is further configured to receive, from the second radio station, communication status information regarding the radio terminal on the second cell, and send the communication status information to the third radio station, and the communication status information is used by the third radio station in order to provide, in the third cell, data communication which has been provided to the radio terminal in the second cell as the secondary cell. ### Claim 17 (depends on 14) The first radio station according to claim 14, wherein the DRB configuration information is not released within the procedure changing the radio station operating the primary cell of the radio terminal from the first radio station to the third radio station. ### Claim 18 A radio terminal comprising: a transceiver; and at least one processor configured to perform Dual Connectivity using either a first cell of a first radio station or a third cell of a third radio station as a primary cell and a second cell of a second radio station as a secondary cell, wherein the at least one processor is further configured to, within a procedure changing the primary cell from the first cell to the third cell: receive a Radio Resource Control (RRC) Connection Reconfiguration message from the first radio station; release, in response to the RRC Connection Reconfiguration message, configuration information on the second cell except for Data Radio Bearer (DRB) configuration information corresponding to a DRB established in the second cell; and re-configure the DRB established in the second cell. ### Claim 19 (depends on 18) The radio terminal according to claim 18, wherein the at least one processor is further configured to re-configure the DRB, which had been established in the second cell, to a DRB in the third cell as the primary cell in response to the RRC Connection Reconfiguration message. ### Claim 20 (depends on 18) The radio terminal according to claim 18, wherein the at least one processor is configured to allow data communication which has been provided to the radio terminal in the second cell as the secondary cell to be resumed in the third cell after the primary cell is changed from the first cell to the third cell. ### Claim 21 (depends on 18) The radio terminal according to claim 18, wherein the DRB configuration information is not released within the procedure changing the primary cell from the first cell to the third cell. ### Claim 22 A communication control method in a first radio station configured to operate a first cell, the method comprising: communicating, via a transceiver of the first radio station, with a radio terminal capable of performing Dual Connectivity using either the first cell or a third cell of a third radio station as a primary cell and a second cell of a second radio station as a secondary cell; and transmitting, within a procedure changing a radio station operating the primary cell of the radio terminal from the first radio station to the third radio station, a Radio Resource Control (RRC) Connection Reconfiguration message to trigger the radio terminal to: release configuration information on the second cell except for Data Radio Bearer (DRB) configuration information corresponding to a DRB established in the second cell; and re-configure the DRB established in the second cell. ### Claim 23 (depends on 22) The communication control method according to claim 22, wherein the RRC Connection Reconfiguration message is further configured to trigger the radio terminal to re-configure the DRB, which had been established in the second cell, to a DRB in the third cell as the primary cell. ### Claim 24 (depends on 22) The communication control method according to claim 22, wherein the DRB configuration information is not released within the procedure changing the radio station operating the primary cell of the radio terminal from the first radio station to the third radio station. ### Claim 25 A communication control method in a radio terminal, the method comprising: performing Dual Connectivity using either a first cell of a first radio station or a third cell of a third radio station as a primary cell and a second cell of a second radio station as a secondary cell; receiving, within a procedure changing the primary cell from the first cell to the third cell, a Radio Resource Control (RRC) Connection Reconfiguration message from the first radio station; releasing, in response to the RRC Connection Reconfiguration message, configuration information on the second cell except for Data Radio Bearer (DRB) configuration information corresponding to a DRB established in the second cell; and re-configuring the DRB established in the second cell. ### Claim 26 (depends on 25) The communication control method according to claim 25, further comprising: re-configuring the DRB, which had been established in the second cell, to a DRB in the third cell as the primary cell in response to the RRC Connection Reconfiguration message. ### Claim 27 A non-transitory computer-readable medium storing therein a program for causing a computer to perform a communication control method in a first radio station configured to operate a first cell, wherein the communication control method comprises: communicating, via a transceiver of the first radio station, with a radio terminal capable of performing Dual Connectivity using either the first cell or a third cell of a third radio station as a primary cell and a second cell of a second radio station as a secondary cell; and transmitting, within a procedure changing a radio station operating the primary cell of the radio terminal from the first radio station to the third radio station, a Radio Resource Control (RRC) Connection Reconfiguration message to trigger the radio terminal to: release configuration information on the second cell except for Data Radio Bearer (DRB) configuration information corresponding to a DRB established in the second cell; and re-configure the DRB established in the second cell. ### Claim 28 A non-transitory computer-readable medium storing therein a program for causing a computer to perform a communication control method in a radio terminal, wherein the communication control method comprises: performing Dual Connectivity using either a first cell of a first radio station or a third cell of a third radio station as a primary cell and a second cell of a second radio station as a secondary cell; receiving, within a procedure changing the primary cell from the first cell to the third cell, a Radio Resource Control (RRC) Connection Reconfiguration message from the first radio station; releasing, in response to the RRC Connection Reconfiguration message, configuration information on the second cell except for Data Radio Bearer (DRB) configuration information corresponding to a DRB established in the second cell; and re-configuring the DRB established in the second cell.