User equipment autonomous serving cell selection in new radio
Methods, systems, and devices for wireless communication are described. A user equipment (UE) may autonomously initiate a handover procedure and select a target base station for the handover procedure. The UE may measure a signal from the source base station or the target base station, or both, and the UE may determine whether specific criteria at both base stations are within a pre-configured range. If the criteria at both base stations are within the pre-configured range, the UE may identify the target base station as a potential candidate for a handover. Accordingly, when the UE determines that radio conditions with the source base station are deteriorating (or fall below a threshold), the UE may initiate a handover to the target base station autonomously and without specific direction from the source base station.
1. An apparatus for wireless communications, comprising:
one or more processors;
memory coupled with the one or more processors; and
instructions stored in the memory and executable by the one or more processors to cause the apparatus to:
receive, from a source cell, first control information indicating a range of values for at least one criterion for UE autonomous cell selection;
transmit, to the source cell and a target cell, an indication of the target cell for handover in accordance with the at least one criterion associated with the target cell being within the range of values;
monitor a first control channel of the source cell for second control information during a first subset of a set of transmission intervals,
the set of transmission intervals corresponding to a threshold time after transmitting the indication of the target cell; and
monitor a second control channel of the target cell for an assignment of resources during a second subset of the set of transmission intervals corresponding to the threshold time after transmitting the indication of the target cell.
2. The apparatus of claim 1 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
receive, from the target cell, the assignment of resources in accordance with the monitoring the second control channel of the target cell; and
establish a connection with the target cell in response to the receiving the assignment of resources from the target cell.
3. The apparatus of claim 1 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
transmit, to the source cell, an indication of the source cell in response to failing to receive the assignment of resources from the target cell within the threshold time; and
maintain a connection with the source cell in accordance with the transmitting the indication of the source cell.
4. The apparatus of claim 1 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
measure a signal for one or more candidate cells,
wherein the one or more candidate cells comprise the target cell, and
wherein the at least one criterion associated with the target cell is within the range of values in accordance with the measuring.
5. The apparatus of claim 4 , wherein:
the at least one criterion corresponds to a first reference signal received power (RSRP) for the source cell and a second RSRP for the target cell, a first reference signal received quality (RSRQ) for the source cell and a second RSRQ for the target cell, or a first signal-to-interference-plus-noise ratio (SINR) for the source cell and a second SINR for the target cell, or a combination thereof in accordance with the measuring.
6. The apparatus of claim 1 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
initiate a handover procedure to the target cell in response to a quality of radio conditions associated with communications with the source cell falling below a threshold,
wherein the indication of the target cell for handover is transmitted in accordance with the handover procedure.
7. The apparatus of claim 1 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
receive radio resource control (RRC) signaling, broadcast information, or downlink control information (DCI), or a combination thereof indicating one or more resources on which to transmit the indication of the target cell,
wherein the indication of the target cell for handover is transmitted in accordance with the RRC signaling, the broadcast information, or the DCI, or the combination thereof.
8. The apparatus of claim 7 , wherein:
the one or more resources comprise a first set of resources configured for transmitting the indication of the target cell to the source cell and a second set of resources configured for transmitting the indication of the target cell to the target cell.
9. The apparatus of claim 7 , wherein:
the one or more resources comprise a common set of resources for transmitting the indication of the target cell to both the source cell and the target cell.
10. The apparatus of claim 1 , wherein the instructions are further executable by the one or more processors to cause the apparatus to:
transmit, to the source cell, one or more measurement reports for the source cell, or the target cell, or both,
wherein the first control information is received in accordance with the one or more measurement reports.
11. The apparatus of claim 10 , wherein:
the first control information further indicates a set of candidate cells configured for the UE autonomous cell selection, the set of candidate cells comprising at least the target cell.
12. A method for wireless communications at a user equipment (UE), comprising:
receiving, from a source cell, first control information indicating a range of values for at least one criterion for UE autonomous cell selection;
transmitting, to the source cell and a target cell, an indication of the target cell for handover in accordance with the at least one criterion associated with the target cell being within the range of values;
monitoring a first control channel of the source cell for second control information during a first subset of a set of transmission intervals,
the set of transmission intervals corresponding to a threshold time after transmitting the indication of the target cell; and
monitoring a second control channel of the target cell for an assignment of resources during a second subset of the set of transmission intervals corresponding to the threshold time after transmitting the indication of the target cell.
13. The method of claim 12 , further comprising:
receiving, from the target cell, the assignment of resources in accordance with the monitoring the second control channel of the target cell; and
establishing a connection with the target cell in response to the receiving the assignment of resources from the target cell.
14. The method of claim 12 , further comprising:
transmitting, to the source cell, an indication of the source cell in response to failing to receive the assignment of resources from the target cell within the threshold time; and
maintaining a connection with the source cell in accordance with the transmitting the indication of the source cell.
15. The method of claim 12 , further comprising:
measuring a signal for one or more candidate cells,
wherein the one or more candidate cells comprise the target cell, and
wherein the at least one criterion associated with the target cell is within the range of values in accordance with the measuring.
16. The method of claim 12 , further comprising:
initiating a handover procedure to the target cell in response to a quality of radio conditions associated with communications with the source cell falling below a threshold,
wherein the indication of the target cell for handover is transmitted in accordance with the handover procedure.
17. The method of claim 12 , further comprising:
receiving radio resource control (RRC) signaling, broadcast information, or downlink control information (DCI), or a combination thereof indicating one or more resources on which to transmit the indication of the target cell,
wherein the indication of the target cell for handover is transmitted in accordance with the RRC signaling, the broadcast information, or the DCI, or the combination thereof.
18. The method of claim 12 , further comprising:
transmitting, to the source cell, one or more measurement reports for the source cell, or the target cell, or both,
wherein the first control information is received in accordance with the one or more measurement reports.
19. The method of claim 18 , wherein:
the first control information further indicates a set of candidate cells configured for the UE autonomous cell selection, the set of candidate cells comprising at least the target cell.
20. A non-transitory computer-readable medium storing code for wireless communications at a user equipment (UE), the code comprising instructions executable by one or more processors to:
receive, from a source cell, first control information indicating a range of values for at least one criterion for UE autonomous cell selection;
transmit, to the source cell and a target cell, an indication of the target cell for handover in accordance with the at least one criterion associated with the target cell being within the range of values;
monitor a first control channel of the source cell for second control information during a first subset of a set of transmission intervals,
the set of transmission intervals corresponding to a threshold time after transmitting the indication of the target cell; and
monitor a second control channel of the target cell for an assignment of resources during a second subset of the set of transmission intervals corresponding to the threshold time after transmitting the indication of the target cell.