Handover execution notification of a wireless device
A wireless device transmits, to a first base station, a measurement result of a cell of a second base station. A command, of a conditional handover towards the cell of the second base station is received, comprises: a cell identifier of the cell; and handover execution condition(s). The handover execution condition(s) comprise at least one of: a reference signal received power; a reference signal received quality; a first time value indicating a time offset for a decision of a handover execution; or a second time value indicating a time duration when the command of the conditional handover is valid. A determination that criteria of the handover execution condition(s) is met by the cell. In response to the determination, a handover execution notification indicating that the wireless device is initiating a random access procedure by transmitting a random access preamble is transmitted via the cell of the second base station.
1. A method comprising:
transmitting, by a wireless device to a first base station, a measurement result of a cell of a second base station;
receiving, by the wireless device from the first base station and based on the measurement result, a command of a conditional handover towards the cell of the second base station, wherein the command comprises:
a cell identifier of the cell; and
at least one handover execution condition, wherein the at least one handover execution condition comprises at least one of:
a reference signal received power;
a reference signal received quality;
a first time value indicating a time offset for a decision of a handover execution; or
a second time value indicating a time duration when the command of the conditional handover is valid;
determining, by the wireless device, that at least one criteria of the at least one handover execution condition is met by the cell; and
transmitting, by the wireless device to the first base station and in response to the determining, a handover execution notification indicating that the wireless device is initiating a random access procedure by transmitting a random access preamble via the cell of the second base station.
2. The method of claim 1 , wherein the first base station suspends transmitting downlink packets to the wireless device via a radio interface in response to the handover execution notification.
3. The method of claim 1 , wherein the at least one handover execution condition comprises the reference signal received power.
4. The method of claim 1 , further comprising transmitting, by the wireless device to the first base station and in response to the determining, at least one of:
a medium access control control element;
a radio resource control message;
a physical layer control indication; or
a second random access preamble associated with the command of the conditional handover.
5. The method of claim 1 , wherein the measurement result comprises at least one of:
a reference signal received power; or
a reference signal received quality.
6. The method of claim 1 , wherein the first base station:
transmits, to the second base station, a first message indicating a handover request for the wireless device based on the measurement result; and
receives, from the second base station and in response to the first message, a second message indicating a handover request acknowledge for the handover request.
7. The method of claim 1 , wherein the second base station:
transmits, to a core network entity and in response to completing the random access procedure, a third message indicating a path switch request for the wireless device, the third message comprising a first tunnel endpoint identifier for packet transmission of the wireless device;
receives, from the core network entity, a fourth message indicating a path switch request acknowledge for the path switch request, the fourth message comprising a second tunnel endpoint identifier for packet transmission of the wireless device; and
transmits, to the first base station, a fifth message indicating a wireless device context release for the wireless device.
8. The method of claim 2 , wherein the at least one handover execution condition comprises the reference signal received power.
9. The method of claim 8 , further comprising transmitting, by the wireless device to the first base station and in response to the determining, at least one of:
a medium access control control element;
a radio resource control message;
a physical layer control indication; or
a second random access preamble associated with the command of the conditional handover.
10. The method of claim 9 , wherein the measurement result comprises at least one of:
a reference signal received power; or
a reference signal received quality.
11. A wireless device comprising:
one or more processors; and
memory storing instructions that, when executed by the one or more processors, cause the wireless device to:
transmit, to a first base station, a measurement result of a cell of a second base station;
receive, from the first base station and based on the measurement result, a command of a conditional handover towards the cell of the second base station, wherein the command comprises:
a cell identifier of the cell; and
at least one handover execution condition, wherein the at least one handover execution condition comprises at least one of:
a reference signal received power;
a reference signal received quality;
a first time value indicating a time offset for a decision of a handover execution; or
a second time value indicating a time duration when the command of the conditional handover is valid;
determine that at least one criteria of the at least one handover execution condition is met by the cell; and
transmit, to the first base station and in response to the determination, a handover execution notification indicating that the wireless device is initiating a random access procedure by transmitting a random access preamble via the cell of the second base station.
12. The wireless device of claim 11 , wherein the first base station suspends transmitting downlink packets to the wireless device via a radio interface in response to the handover execution notification.
13. The wireless device of claim 11 , wherein the at least one handover execution condition comprises the reference signal received power.
14. The wireless device of claim 11 , further comprising transmitting, by the wireless device to the first base station and in response to the determination, at least one of:
a medium access control control element;
a radio resource control message;
a physical layer control indication; or
a second random access preamble associated with the command of the conditional handover.
15. The wireless device of claim 11 , wherein the measurement result comprises at least one of:
a reference signal received power; or
a reference signal received quality.
16. The wireless device of claim 11 , wherein the first base station:
transmits, to the second base station, a first message indicating a handover request for the wireless device based on the measurement result; and
receives, from the second base station and in response to the first message, a second message indicating a handover request acknowledge for the handover request.
17. The wireless device of claim 11 , wherein the second base station:
transmits, to a core network entity and in response to completing the random access procedure, a third message indicating a path switch request for the wireless device, the third message comprising a first tunnel endpoint identifier for packet transmission of the wireless device;
receives, from the core network entity, a fourth message indicating a path switch request acknowledge for the path switch request, the fourth message comprising a second tunnel endpoint identifier for packet transmission of the wireless device; and
transmits, to the first base station, a fifth message indicating a wireless device context release for the wireless device.
18. The wireless device of claim 12 , wherein the at least one handover execution condition comprises the reference signal received power.
19. The wireless device of claim 18 , further comprising transmitting, by the wireless device to the first base station and in response to the determination, at least one of:
a medium access control control element;
a radio resource control message;
a physical layer control indication; or
a second random access preamble associated with the command of the conditional handover.
20. A system comprising:
a wireless device comprising:
one or more first processors; and
first memory storing first instructions that, when executed by the one or more first processors, cause the wireless device to:
transmit a measurement result of a cell of a second base station;
receive a command of a conditional handover towards the cell of the second base station, wherein the command comprises:
a cell identifier of the cell; and
at least one handover execution condition, wherein the at least one handover execution condition comprises at least one of:
a reference signal received power;
a reference signal received quality;
a first time value indicating a time offset for a decision of a handover execution; or
a second time value indicating a time duration when the command of the conditional handover is valid;
determine that at least one criteria of the at least one handover execution condition is met by the cell; and
transmit, in response to the determination, a handover execution notification indicating that the wireless device is initiating a random access procedure by transmitting a random access preamble via the cell of the second base station; and
a first base station comprising:
one or more second processors; and
second memory storing second instructions that, when executed by the one or more second processors, cause the first base station to:
receive the measurement result of a cell of a second base station;
based on the measurement result, transmit the command of a conditional handover; and
receive the handover execution notification.