Radio terminal, base station, and methods and non-transitory computer-readable media therefor
AssigneeNEC Corporation
InventorsHisashi Futaki, Sadafuku Hayashi
Life of this patent
Estimating the term…
Abstract
When a radio terminal (2) in a first RAT RRC_INACTIVE state in the first radio access network (RAN) (3) and having a Non-Access Stratum (NAS) connection with a first core network (CN) (4) associated with the first RAT moves to a cell (51) of a second RAN (6), the radio terminal (2) alters an RRC state transition operation of the radio terminal (2) depending on whether the second RAN (6) supports interworking with at least one of the first CN (4) and the first RAN (3).
Claims13
A radio terminal comprising:
- at least one transceiver;
- and
- at least one processor configured to control the at least one transceiver in one or more cells of a first radio access network (RAN) and in one or more cells of a second RAN, the first RAN supporting a first Radio Access Technology (RAT) and having an interface with a first core network (CN), the second RAN supporting a second RAT,
- wherein the at least one processor is configured to control state transitions of the radio terminal among an RRC_CONNECTED state of the first RAT, an RRC_INACTIVE state of the first RAT, and an RRC_IDLE state of the first RAT,
- wherein the at least one processor is configured to control state transitions of the radio terminal between an RRC_CONNECTED state of the second RAT and an RRC_IDLE state of the second RAT,
- wherein the at least one processor is configured to, if the radio terminal in the RRC_INACTIVE state of the first RAT in the first RAN and having a Non-Access Stratum (NAS) connection with the first CN moves to a cell of the second RAN, alter an RRC state transition operation of the radio terminal depending on whether the second RAN supports interworking with at least one of the first CN and the first RAN,
- wherein the at least one processor is configured to, if the second RAN supports interworking with at least one of the first CN and the first RAN, then transition the radio terminal to the RRC_CONNECTED state of the second RAT directly from the RRC_INACTIVE state of the first RAT,
- wherein the RRC_INACTIVE state of the first RAT is not a sub-state of the RRC_IDLE state of the first RAT, and
- wherein the RRC_INACTIVE state of the first RAT is not a sub-state of the RRC_CONNECTED state of the first RAT.
A base station supporting a second Radio Access Technology (RAT), the base station comprising:
- a memory;
- and
- at least one processor configured to transmit, in a cell of the base station, an information element used by a radio terminal to determine whether the base station supports a particular RRC state transition,
- wherein the particular RRC state transition includes a state transition of the radio terminal directly from an RRC_INACTIVE state of a first RAT to an RRC_CONNECTED state of the second RAT,
- wherein the RRC_INACTIVE state of the first RAT is not a sub-state of an RRC_IDLE state of the first RAT, and
- wherein the RRC_INACTIVE state of the first RAT is not a sub-state of a RRC_CONNECTED state of the first RAT.
A method for a radio terminal configured to operate in cells of a first radio access network (RAN) and cells of a second RAN, the first RAN supporting a first Radio Access Technology (RAT) and having an interface with a first core network (CN), the second RAN supporting a second RAT, the method comprising:
- controlling state transitions of the radio terminal among an RRC_CONNECTED state of the first RAT, an RRC_INACTIVE state of the first RAT, and an RRC_IDLE state of the first RAT;
- controlling state transitions of the radio terminal between an RRC_CONNECTED state of the second RAT and an RRC_IDLE state of the second RAT;
- and
- if the radio terminal in the RRC_INACTIVE state of the first RAT in the first RAN and having a Non-Access Stratum (NAS) connection with the first CN moves to a cell of the second RAN, altering an RRC state transition operation of the radio terminal depending on whether the second RAN supports interworking with at least one of the first CN and the first RAN,
- wherein said altering comprises, if the second RAN supports interworking with at least one of the first CN and the first RAN, then transitioning the radio terminal to the RRC_CONNECTED state of the second RAT directly from the RRC_INACTIVE state of the first RAT,
- wherein the RRC_INACTIVE state of the first RAT is not a sub-state of the RRC_IDLE state of the first RAT, and
- wherein the RRC_INACTIVE state of the first RAT is not a sub-state of the RRC_CONNECTED state of the first RAT.
Dependencies are inferred from the claim text.