Path switch to indirect communication through relay UE device in RRC connection state other than RRC connected
A base station transmits a Radio Resource Control (RRC) Reconfiguration message to a remote user equipment (UE) device to initiate a path switch from direct communication with the remote UE device to indirect communication through a relay UE device. The relay UE device is an RRC connection state other than RRC Connected (RRC CONN) when the path switch is initiated. The remote UE device transmits an RRC Reconfiguration Complete message to the base station through the relay UE device. In response to receiving the RRC Reconfiguration Complete message, the relay UE performs RRC Connection Establishment with the base station when the relay UE device is in an RRC IDLE state and performs RRC Resume with the base station when the relay UE device is in an RRC INACTIVE state. The relay UE device transmits the RRC Reconfiguration Complete message to the base station.
1 . A relay user equipment (UE) device comprising:
a controller configured to maintain the relay UE device in a Radio Resource Control (RRC) state with a base station other than RRC Connected (RRC CONN);
a receiver configured to receive an RRC Reconfiguration Complete message directed to the base station from a remote UE device over a PC5 communication link; and
a transmitter configured to:
transmit, in response to receiving the RRC Reconfiguration Complete message, a first RRC message used for RRC Connection Establishment to the base station when the relay UE device is in an RRC IDLE state,
transmit, in response to receiving the RRC Reconfiguration Complete message, a second RRC message used for RRC Connection Resume to the base station when the relay UE device is in an RRC INACTIVE state, and
transmit the RRC Reconfiguration Complete message to the base station over a Uu communication link available in response to one of the first RRC message and the second RRC message.
2 . The relay UE device of claim 1 , wherein
the RRC Reconfiguration Complete message is transmitted by the remote UE device in response to receipt of an RRC Reconfiguration message at the remote UE device transmitted from the base station over a Uu direct communication link between the base station and the remote UE device, the RRC Reconfiguration message initiating a path switch from a direct communication link between the remote UE device and the base station to an indirect communication link between the remote UE device and the base station through the relay UE device.
3 . The relay UE device of claim 1 , wherein:
the receiver is further configured to receive an RRC Resume message after transmitting the second RRC message, and
the transmitter is further configured to transmit an RRC Resume Complete message after receiving the RRC Resume message.
4 . The relay UE device of claim 1 , wherein
the transmitter and receiver are configured to operate in accordance with at least one revision of the 3rd Generation Partnership Project (3GPP) New Radio (NR) V2X communication specification.
5 . A remote user equipment (UE) device comprising:
a transmitter configured to transmit a measurement report over a direct Uu communication link to a base station, the measurement report comprising a measurement of a signal transmitted from at least one candidate relay UE device in a Radio Resource Control (RRC) state other than RRC Connected (RRC CONN); and
a receiver configured to receive, from the base station over the direct Uu communication link, an RRC Reconfiguration Message identifying a target relay UE device selected from the at least one candidate relay UE device by the base station, the target relay UE device in the RRC state other than RRC Connected (RRC CONN),
the transmitter further configured to transmit an RRC Reconfiguration Complete message to the base station by transmitting the RRC Reconfiguration Complete message to the target relay UE device over a PC5 communication link,
the RRC Reconfiguration Complete message invoking the target relay UE device to perform RRC Connection Establishment with the base station when the target relay UE device is in an RRC IDLE state,
the RRC Reconfiguration Complete message invoking the target relay UE device to perform RRC Resume with the base station when the target relay UE device is in an RRC INACTIVE state.
6 . The remote UE device of claim 5 , wherein the signal is a Sidelink Discovery message.
7 . The remote UE device of claim 5 , wherein:
the measurement report comprises at least one measurement for the at least one candidate relay UE device, each measurement of the at least one measurement corresponding to a different candidate relay UE device of the at least one candidate relay UE device, and the at least one candidate relay UE device includes a first candidate relay UE device in RRC CONN and the target relay UE device in the RRC state other than RRC Connected (RRC CONN).
8 . The remote UE device of claim 5 , wherein the transmitter and receiver are configured to operate in accordance with at least one revision of the 3rd Generation Partnership Project (3GPP) New Radio (NR) V2X communication specification.
9 . The relay UE device of claim 1 , the receiver is configured to receive a RRC Reconfiguration message from the base station in response to the transmitter transmitting the first RRC message to the base station, and
the controller is configured to switch the relay UE device to RRC Connected (RRC CONN) in response to the receiver receiving the RRC Reconfiguration message.
10 . The relay UE device of claim 1 , wherein the controller is configured to switch the relay UE device to RRC Connected (RRC CONN) in response to the transmitter transmitting the first RRC message to the base station, and
the receiver is configured to receive a RRC Reconfiguration message from the base station in response to the transmitter transmitting the first RRC message to the base station.
11 . The relay UE device of claim 10 , wherein the RRC Reconfiguration message includes an identifier of the remote UE device.
12 . The relay UE device of claim 1 , wherein the controller is configured to switch the relay UE device to RRC Connected (RRC CONN) in response to the transmitter transmitting the second RRC message to the base station, and
the receiver is configured to receive a RRC Reconfiguration message from the base station in response to the controller switching the relay UE device to RRC Connected (RRC CONN).
13 . The relay UE device of claim 12 , wherein the RRC Reconfiguration message includes an identifier of the remote UE device.
14 . A method of a relay user equipment (UE) device, the method comprising:
in a Radio Resource Control (RRC) state with a base station other than RRC Connected (RRC CONN), receiving an RRC Reconfiguration Complete message directed to the base station from a remote UE device over a PC5 communication link;
transmitting, in response to receiving the RRC Reconfiguration Complete message, a first RRC message used for RRC Connection Establishment to the base station when the relay UE device is in an RRC IDLE state;
transmitting, in response to receiving the RRC Reconfiguration Complete message, a second RRC message used for RRC Connection Resume to the base station when the relay UE device is in an RRC INACTIVE state; and
transmitting the RRC Reconfiguration Complete message to the base station over a Uu communication link available in response to one of the first RRC message and the second RRC message.
15 . A computer-readable recording medium having embodied thereon computer-readable instructions which, when executed by a processor, cause the processor to perform the method of claim 14 .
16 . A chipset of a relay user equipment (UE) device, the chipset comprising:
a memory configured to store computer-readable instructions; and
a processor configured to execute the computer-readable instructions and, when executing the computer-readable instructions, the processor is configured to execute a method including:
in a Radio Resource Control (RRC) state with a base station other than RRC Connected (RRC CONN), receiving an RRC Reconfiguration Complete message directed to the base station from a remote UE device over a PC5 communication link;
transmitting, in response to receiving the RRC Reconfiguration Complete message, a first RRC message used for RRC Connection Establishment to the base station when the relay UE device is in an RRC IDLE state;
transmitting, in response to receiving the RRC Reconfiguration Complete message, a second RRC message used for RRC Connection Resume to the base station when the relay UE device is in an RRC INACTIVE state; and
transmitting the RRC Reconfiguration Complete message to the base station over a Uu communication link available in response to one of the first RRC message and the second RRC message.
17 . A method of a remote user equipment (UE) device, the method comprising:
transmitting a measurement report over a direct Uu communication link to a base station, the measurement report comprising a measurement of a signal transmitted from at least one candidate relay UE device in a Radio Resource Control (RRC) state other than RRC Connected (RRC CONN);
receiving, from the base station over the direct Uu communication link, an RRC Reconfiguration Message identifying a target relay UE device selected from the at least one candidate relay UE device by the base station, the target relay UE device in the RRC state other than RRC Connected (RRC CONN);
transmitting an RRC Reconfiguration Complete message to the base station by transmitting the RRC Reconfiguration Complete message to the target relay UE device over a PC5 communication link,
the RRC Reconfiguration Complete message invoking the target relay UE device to perform RRC Connection Establishment with the base station when the target relay UE device is in an RRC IDLE state,
the RRC Reconfiguration Complete message invoking the target relay UE device to perform RRC Resume with the base station when the target relay UE device is in an RRC INACTIVE state.
18 . A computer-readable recording medium having embodied thereon computer-readable instructions which, when executed by a processor, cause the processor to perform the method of claim 17 .
19 . A chipset of a remote user equipment (UE) device, the chipset comprising:
a memory configured to store computer-readable instructions; and
a processor configured to execute the computer-readable instructions and, when executing the computer-readable instructions, the processor is configured to execute a method including:
transmitting a measurement report over a direct Uu communication link to a base station, the measurement report comprising a measurement of a signal transmitted from at least one candidate relay UE device in a Radio Resource Control (RRC) state other than RRC Connected (RRC CONN);
receiving, from the base station over the direct Uu communication link, an RRC Reconfiguration Message identifying a target relay UE device selected from the at least one candidate relay UE device by the base station, the target relay UE device in the RRC state other than RRC Connected (RRC CONN);
transmitting an RRC Reconfiguration Complete message to the base station by transmitting the RRC Reconfiguration Complete message to the target relay UE device over a PC5 communication link,
the RRC Reconfiguration Complete message invoking the target relay UE device to perform RRC Connection Establishment with the base station when the target relay UE device is in an RRC IDLE state,
the RRC Reconfiguration Complete message invoking the target relay UE device to perform RRC Resume with the base station when the target relay UE device is in an RRC INACTIVE state.
20 . A system comprising:
a remote user equipment (UE) device; and
a relay UE device,
wherein the remote UE device includes:
a transmitter configured to transmit a measurement report over a direct Uu communication link to a base station, the measurement report comprising a measurement of a signal transmitted from at least one candidate relay UE device in a Radio Resource Control (RRC) state other than RRC Connected (RRC CONN); and
a receiver configured to receive, from the base station over the direct Uu communication link, an RRC Reconfiguration Message identifying the relay UE device as a target relay UE device selected from the at least one candidate relay UE device by the base station, the target relay UE device in the RRC state other than RRC Connected (RRC CONN),
the transmitter further configured to transmit an RRC Reconfiguration Complete message to the base station by transmitting the RRC Reconfiguration Complete message to the target relay UE device over a PC5 communication link,
the RRC Reconfiguration Complete message invoking the target relay UE device to perform RRC Connection Establishment with the base station when the target relay UE device is in an RRC IDLE state,
the RRC Reconfiguration Complete message invoking the target relay UE device to perform RRC Resume with the base station when the target relay UE device is in an RRC INACTIVE state, and
wherein the relay UE device includes:
a receiver configured to, in the Radio Resource Control (RRC) state with the base station other than RRC Connected (RRC CONN), receive the RRC Reconfiguration Complete message directed to the base station from the remote UE device over the PC5 communication link; and
a transmitter configured to:
transmit, in response to receiving the RRC Reconfiguration Complete message, a first RRC message used for RRC Connection Establishment to the base station when the relay UE device is in an RRC IDLE state,
transmit, in response to receiving the RRC Reconfiguration Complete message, a second RRC message used for RRC Connection Resume to the base station when the relay UE device is in an RRC INACTIVE state, and
transmit the RRC Reconfiguration Complete message to the base station over a Uu communication link available in response to one of the first RRC message and the second RRC message.