# US 2016/0262149 A1 · Radio communication system, base station apparatus, radio terminal, and communication control method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2016/0262149 A1 - Document ID: US20160262149A1 - Status: Published application - Kind: A1 - Application number: 15/028,915 - Filed: 2014-05-07 - Published: 2016-09-08 - Earliest claimed: 2013-10-31 - Assignees: NEC Corporation - Applicants: NEC Corporation - Inventors: Hisashi FUTAKI; Hiroto SUGAHARA; Hiroaki AMINAKA - Web page: https://patentgrep.com/patent/US20160262149A1 ## CPC - H04W 72/27: between access points - H04B 7/02: Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas (RAKE receivers H04B1/7115) - H04L 5/001: {the frequencies being arranged in component carriers} - H04L 5/0091: {Signalling for the administration of the divided path, e.g. signalling of configuration information} - H04W 16/32: Hierarchical cell structures - H04W 24/10: Scheduling measurement reports {; Arrangements for measurement reports} - H04W 28/082: among bearers or channels - H04W 28/0861: {between base stations} - H04W 52/367: {Power values between minimum and maximum limits, e.g. dynamic range} - H04W 72/12: Wireless traffic scheduling - H04W 72/542: using measured or perceived quality - H04W 76/15: Setup of multiple wireless link connections - H04W 92/20: between access points - H04W 52/146: {Uplink power control} - H04W 52/365: {Power headroom reporting} - H04W 88/06: adapted for operation in multiple networks {or having at least two operational modes}, e.g. multi-mode terminals - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A radio communication system includes a first base station (11) that manages a first cell (110), a second base station (12) that manages a second cell (120), and a radio terminal (2). The radio terminal (2) supports dual connectivity involving a bearer split in which a first network bearer between the radio terminal (2) and a core network (3) is split over the first base station (11) and the second base station (12). The first base station (11) receives, from the second base station (12), bearer split status information about communication of the first network bearer in the second base station (12), and performs control of an access stratum related to the first network bearer. It is thus possible to contribute, for example, to an improvement in control of an access stratum when dual connectivity involving a bearer split is performed. ## Claims ### Claim 1 A radio communication system comprising: a first base station that manages a first cell; a second base station that manages a second cell; and a radio terminal that supports dual connectivity involving a bearer split in which a first network bearer between the radio terminal and a core network is split over the first base station and the second base station, wherein the first base station is configured to receive, from the second base station, bearer split status information about communication of the first network bearer in the second base station, and to perform control of an access stratum related to the first network bearer. ### Claim 2 (depends on 1) The radio communication system according to claim 1, wherein the bearer split status information indicates a communication status monitored for each network bearer to be subjected to a bearer split, monitored for each radio bearer mapped to a network bearer to be subjected to a bearer split, monitored for the second cell, monitored for the second base station, monitored for the second cell and a plurality of radio terminals, or monitored for the second base station and a plurality of radio terminals. ### Claim 3 (depends on 1) The radio communication system according to claim 1, wherein the bearer split status information includes at least one of communication status information, radio resource control information, and admission control information. ### Claim 4 (depends on 3) The radio communication system according to claim 3, wherein the bearer split status information includes the communication status information indicating a communication status of the first network bearer in the second base station, and the communication status information indicates at least one of statistics of throughput, statistics of allocated radio resources, statistics of packet losses, statistics of power headroom, and information about retransmission control in a Radio Link Control (RLC) sublayer. ### Claim 5 (depends on 3) The radio communication system according to claim 3, wherein the bearer split status information includes the radio resource control information relating to radio resources used in the second cell for the first network bearer, and the radio resource control information indicates at least one of information about an increase or decrease in radio resources, information about available radio resources, and information about surplus radio resources. ### Claim 6 (depends on 3) The radio communication system according to claim 3, wherein the bearer split status information includes the admission control information relating to admission executed in the second cell on data of the first network bearer, and the admission control information indicates at least one of information about whether or not to admit a new bearer split, information about a wait time until a new bearer split is acceptable, information about a wait time until a request for a new bearer split is made, information about expected throughput, and information about an expected amount of radio resources to be allocated. ### Claim 7 (depends on 1) The radio communication system according to claim 1, wherein the control of the access stratum includes control of a Logical Channel Prioritization (LCP) procedure for generating, in the radio terminal, at least one of a first Medium Access Control Protocol Data Unit (MAC PDU) for uplink transmission in the first cell and a second MAC PDU for uplink transmission in the second cell. ### Claim 8 (depends on 7) The radio communication system according to claim 7, wherein the control of the LCP procedure includes at least one of adjusting a Prioritized Bit Rate (PBR) applied to an uplink logical channel of the first network bearer and adjusting a PBR applied to an uplink logical channel of a second network bearer transmitted via the first cell without being subjected to the bearer split. ### Claim 9 (depends on 1) The radio communication system according to claim 1, wherein the control of the access stratum includes uplink transmission power control of at least one of the first and second cells. ### Claim 10 (depends on 9) The radio communication system according to claim 9, wherein the uplink transmission power control includes at least one of adjusting maximum transmission power allowed for the radio terminal in the first cell and adjusting maximum transmission power allowed for the radio terminal in the second cell. ### Claim 11 (depends on 1) The radio communication system according to claim 1, wherein the control of the access stratum includes control of downlink scheduling in at least one of the first and second cells. ### Claim 12 (depends on 11) The radio communication system according to claim 11, wherein the control of the downlink scheduling includes at least one of adjusting a Prioritized Bit Rate (PBR) applied to a downlink logical channel of the first network bearer and adjusting a PBR applied to a downlink logical channel of a second network bearer transmitted via the first cell without being subjected to the bearer split. ### Claim 13 (depends on 1) The radio communication system according to claim 1, wherein the second base station is configured to request the first base station to adjust an amount of downlink data that relates to the first network bearer and is split in the first base station and transmitted from the first base station to the second base station. ### Claim 14 (depends on 1) The radio communication system according to claim 1, wherein the second base station is configured to request the first base station to adjust maximum transmission power allowed for the radio terminal in the first or second cell. ### Claim 15 (depends on 1) The radio communication system according to claim 1, wherein the second base station is configured to request the first base station to adjust a Prioritized Bit Rate (PBR) that is applied to an uplink logical channel of the first network bearer when the radio terminal generates a Medium Access Control Protocol Data Unit (MAC PDU) for uplink transmission in the first or second cell. ### Claim 16 (depends on 1) The radio communication system according to claim 1, wherein the second base station is configured to request the first base station to stop the dual connectivity involving the bearer split related to the radio terminal. ### Claim 17 A base station apparatus comprising: a memory; and at least one hardware processer coupled to the memory and configured to execute modules comprising a communication controller configured to control dual connectivity involving a bearer split in which a first network bearer between a radio terminal and a core network is split over the base station apparatus and a neighbor base station, wherein the communication controller is configured to receive, from the neighbor base station, bearer split status information about communication of the first network bearer in the neighbor base station, and to perform control of an access stratum related to the first network bearer. ### Claim 18 (depends on 17) The base station apparatus according to claim 17, wherein the control of the access stratum includes control of a Logical Channel Prioritization (LCP) procedure for generating, in the radio terminal, at least one of a first Medium Access Control Protocol Data Unit (MAC PDU) for uplink transmission in a first cell managed by the base station apparatus and a second MAC PDU for uplink transmission in a second cell managed by the neighbor base station. ### Claim 19 (depends on 18) The base station apparatus according to claim 18, wherein the control of the LCP procedure includes at least one of adjusting a Prioritized Bit Rate (PBR) applied to an uplink logical channel of the first network bearer and adjusting a PBR applied to an uplink logical channel of a second network bearer transmitted via the first cell without being subjected to the bearer split. ### Claim 20 (depends on 17) The base station apparatus according to claim 17, wherein the control of the access stratum includes uplink transmission power control of at least one of a first cell managed by the base station apparatus and a second cell managed by the neighbor base station. ### Claim 21 (depends on 20) The base station apparatus according to claim 20, wherein the uplink transmission power control includes at least one of adjusting maximum transmission power allowed for the radio terminal in the first cell and adjusting maximum transmission power allowed for the radio terminal in the second cell. ### Claim 22 (depends on 17) The base station apparatus according to claim 17, wherein the control of the access stratum includes control of downlink scheduling in at least one of a first cell managed by the base station apparatus and a second cell managed by the neighbor base station. ### Claim 23 (depends on 22) The base station apparatus according to claim 22, wherein the control of the downlink scheduling includes at least one of adjusting a Prioritized Bit Rate (PBR) applied to a downlink logical channel of the first network bearer and adjusting a PBR applied to a downlink logical channel of a second network bearer transmitted via the first cell without being subjected to the bearer split. ### Claim 24 (depends on 17) The base station apparatus according to claim 17, wherein the bearer split status information includes at least one of communication status information, radio resource control information, and admission control information. ### Claim 25 (depends on 24) The base station apparatus according to claim 24, wherein the bearer split status information includes the communication status information indicating a communication status of the first network bearer in the neighbor base station, and the communication status information indicates at least one of statistics of throughput, statistics of allocated radio resources, statistics of packet losses, statistics of power headroom, and information about retransmission control in a Radio Link Control (RLC) sublayer. ### Claim 26 (depends on 24) The base station apparatus according to claim 24, wherein the bearer split status information includes the radio resource control information relating to radio resources used in a cell managed by the neighbor base station for the first network bearer, and the radio resource control information indicates at least one of information about an increase or decrease in radio resources, information about available radio resources, and information about surplus radio resources. ### Claim 27 (depends on 24) The base station apparatus according to claim 24, wherein the bearer split status information includes the admission control information relating to admission, executed in a cell managed by the neighbor base station, on data of the first network bearer, and the admission control information indicates at least one of information about whether or not to admit a new bearer split, information about a wait time until a new bearer split is acceptable, information about a wait time until a request for a new bearer split is made, information about expected throughput, and information about an expected amount of radio resources to be allocated. ### Claim 28 A base station apparatus comprising: a memory; and at least one hardware processer coupled to the memory and configured to execute modules comprising a communication controller configured to control dual connectivity involving a bearer split in which a first network bearer between a radio terminal and a core network is split over the base station apparatus and a neighbor base station, wherein the communication controller is configured to send, to the neighbor base station, bearer split status information about communication of the first network bearer in the base station apparatus, and the bearer split status information triggers the neighbor base station to perform control of an access stratum related to the first network bearer. ### Claim 29 (depends on 28) The base station apparatus according to claim 28, wherein the control of the access stratum includes control of a Logical Channel Prioritization (LCP) procedure for generating, in the radio terminal, at least one of a first Medium Access Control Protocol Data Unit (MAC PDU) for uplink transmission in a first cell managed by the neighbor base station and a second MAC PDU for uplink transmission in a second cell managed by the base station apparatus. ### Claim 30 (depends on 28) The base station apparatus according to claim 28, wherein the control of the access stratum includes uplink transmission power control of at least one of a first cell managed by the neighbor base station and a second sell managed by the base station apparatus. ### Claim 31 (depends on 28) The base station apparatus according to claim 28, wherein the control of the access stratum includes control of downlink scheduling in at least one of a first cell managed by the neighbor base station and a second cell managed by the base station apparatus. ### Claim 32 (depends on 28) The base station apparatus according to claim 28, wherein the bearer split status information includes at least one of communication status information, radio resource control information, and admission control information. ### Claim 33 (depends on 32) The base station apparatus according to claim 32, wherein the bearer split status information includes the communication status information indicating a communication status of the first network bearer in the base station apparatus, and the communication status information indicates at least one of statistics of throughput, statistics of allocated radio resources, statistics of packet losses, statistics of power headroom, and information about retransmission control in a Radio Link Control (RLC) sublayer. ### Claim 34 (depends on 32) The base station apparatus according to claim 32, wherein the bearer split status information includes the radio resource control information relating to radio resources used in a cell managed by the base station apparatus for the first network bearer, and the radio resource control information indicates at least one of information about an increase or decrease in radio resources, information about available radio resources, and information about surplus radio resources. ### Claim 35 (depends on 32) The base station apparatus according to claim 32, wherein the bearer split status information includes the admission control information relating to admission, executed in a cell managed by the base station apparatus, on data of the first network bearer, and the admission control information indicates at least one of information about whether or not to admit a new bearer split, information about a wait time until a new bearer split is acceptable, information about a wait time until a request for a new bearer split is made, information about expected throughput, and information about an expected amount of radio resources to be allocated. ### Claim 36 (depends on 28) The base station apparatus according to claim 28, wherein the communication controller is further configured to request the neighbor base station to adjust an amount of downlink data that relates to the first network bearer and is split in the neighbor base station and transmitted from the neighbor base station to the base station apparatus. ### Claim 37 (depends on 28) The base station apparatus according to claim 28, wherein the communication controller is further configured to request the neighbor base station to adjust maximum transmission power allowed for the radio terminal in a second cell managed by the base station apparatus. ### Claim 38 (depends on 28) The base station apparatus according to claim 28, wherein the communication controller is further configured to request the neighbor base station to adjust a Prioritized Bit Rate (PBR) that is applied to an uplink logical channel of the first network bearer when the radio terminal generates a Medium Access Control Protocol Data Unit (MAC PDU) for uplink transmission in a second cell managed by the base station apparatus. ### Claim 39 (depends on 28) The base station apparatus according to claim 28, wherein the communication controller is further configured to request the neighbor base station to stop the dual connectivity involving the bearer split related to the radio terminal. ### Claim 40 (depends on 1) A radio terminal that is used in the radio communication system according to claim 1, the radio terminal comprising: a memory; and at least one hardware processer coupled to the memory and configured to execute modules comprising a communication controller configured to control dual connectivity involving a bearer split in which the first network bearer is split over first and second base stations, wherein the communication controller is configured to perform control of an access stratum related to the first network bearer based on an instruction from the first base station. ### Claim 41 A communication control method comprising: starting, by a first base station, communication of dual connectivity involving a bearer split in which a first network bearer between a radio terminal and a core network is split over the first base station and a second base station; receiving, by the first base station from the second base station, bearer split status information about communication of the first network bearer in the second base station, and performing, by the first base station, control of an access stratum related to the first network bearer. ### Claim 42 A communication control method comprising: starting, by a second base station, communication of dual connectivity involving a bearer split in which a first network bearer between a radio terminal and a core network is split over a first base station and the second bases station; and transmitting, to the first base station, bearer split status information about communication of the first network bearer in the second base station, wherein the bearer split status information triggers the first base station to perform control of an access stratum related to the first network bearer. ### Claim 43 (depends on 41) A non-transitory computer readable medium storing a program for causing a computer to perform a communication control method according to claim 41.