Multi-panel control channel order, initial access, and handover

1. A method for wireless communication at a user equipment (UE), comprising:

communicating with a first base station using a first antenna array of a plurality of antenna arrays of the UE;

receiving, from the first base station, an indication that the UE is to use a second antenna array of the plurality of antenna arrays to transmit a random access signal; and

transmitting, to the first base station or a second base station, the random access signal using the second antenna array based at least in part on the received indication.

2. The method of claim 1 , wherein receiving the indication comprises:

receiving a control channel order that comprises the indication that the UE is to use the second antenna array to transmit the random access signal.

3. The method of claim 2 , wherein the received control channel order comprises a preamble index, the method further comprising:

identifying a mapping between a set of preamble indices and a set of antenna arrays; and

determining the second antenna array to use transmit the random access signal based at least in part on the preamble index and the identified mapping.

4. The method of claim 2 , wherein receiving the received control channel order that comprises the indication comprises:

receiving a downlink control information indicating the second antenna array.

5. The method of claim 2 , further comprising:

receiving, before receiving the control channel order that comprises the indication, a downlink reference signal associated with the second antenna array; and

determining to use the second antenna array to transmit the random access signal based at least in part on the received downlink reference signal being associate with the second antenna array.

6. The method of claim 1 , wherein:

receiving the indication comprises receiving, from the first base station, a signal indicating that the UE is to establish a connection with the second base station, the received signal indicating the second antenna array; and

transmitting the random access signal comprises transmitting the random access signal to the second base station using the second antenna array based at least in part on the received signal.

7. The method of claim 6 , further comprising:

performing, using the second antenna array indicated by the received signal, an initial access procedure with the second base station, wherein the transmitted random access signal is a part of the initial access procedure, the first base station is a primary base station of a dual connectivity configuration, and the second base station is a secondary base station of the dual connectivity configuration.

8. The method of claim 6 , further comprising:

performing, using the second antenna array indicated by the received signal, a handover procedure from the first base station to the second base station, wherein the transmitted random access signal is a part of the handover procedure, the first base station is a source base station of the handover procedure, and the second base station is a target base station of the handover procedure.

9. The method of claim 1 , wherein receiving the indication comprises receiving, from the first base station, a first message indicating that the UE is to establish a connection with the second base station, and the method further comprises:

transmitting, to the first base station, a second message indicating the second antenna array that the UE is to use to establish the connection with the second base station; and

transmitting the random access signal comprises transmitting the random access signal to the second base station using the second antenna array based at least in part on the transmitted second message.

10. The method of claim 9 , further comprising:

performing, using the second antenna array indicated by the transmitted second message, an initial access procedure with the second base station, wherein the transmitted random access signal is a part of the initial access procedure, the first base station is a primary base station of a dual connectivity configuration, and the second base station is a secondary base station of the dual connectivity configuration.

11. The method of claim 9 , further comprising:

performing, using the second antenna array indicated by the transmitted second message, a handover procedure from the first base station to the second base station, wherein the transmitted random access signal is a part of the handover procedure, the first base station is a source base station of the handover procedure, and the second base station is a target base station of the handover procedure.

12. The method of claim 1 , wherein:

receiving the indication comprises:

receiving, from the first base station, a first signal indicating that the UE is to establish a connection with the second base station;

receiving, from the first base station, a second signal indicating the second antenna array; and

transmitting the random access signal comprises transmitting the random access signal to the second base station using the second antenna array based at least in part on the received signal.

13. The method of claim 1 , further comprising:

receiving, from the first base station in response to the transmitted random access signal, a timing advance value for the second antenna array.

14. A method for wireless communication at a first base station, comprising:

communicating with a user equipment (UE);

identifying a plurality of antenna arrays of the UE, the plurality of antenna arrays comprising at least a first antenna array used to communicate with the first base station and a second antenna array; and

transmitting, to the UE, an indication that the UE is to use the second antenna array to transmit a random access signal to the first base station or a second base station.

15. The method of claim 14 , further comprising:

receiving, from the UE based at least in part on the transmitted indication, the random access signal; and

transmitting, to the UE in response to the received random access signal, a timing advance value for the second antenna array.

16. The method of claim 14 , wherein transmitting the indication comprises:

transmitting a control channel order that comprises the indication that the UE is to use the second antenna array to transmit the random access signal.

17. The method of claim 16 , further comprising:

identifying a mapping between a set of preamble indices and a set of antenna arrays of the UE; and

determining a preamble index corresponding to the second antenna array that the UE is to use to transmit the random access signal, wherein the transmitted indication comprises the determined preamble index.

18. The method of claim 16 , wherein transmitting the received control channel order that comprises the indication comprises:

transmitting a downlink control information indicating the second antenna array.

19. The method of claim 16 , further comprising:

transmitting, before transmitting the control channel order that comprises the indication, a downlink reference signal associated with the second antenna array, the UE to use the second antenna array to transmit the random access signal based at least in part on the downlink reference signal being associate with the second antenna array.

20. The method of claim 14 , wherein:

transmitting the indication comprises transmitting a signal indicating that the UE is to establish a connection with the second base station, the transmitted signal indicating the second antenna array.

21. The method of claim 20 , wherein the signal indicating that the UE is to establish the connection with the second base station comprises a request for the UE to perform an initial access procedure with the second base station, wherein the first base station is a primary base station of a dual connectivity configuration, and the second base station is a secondary base station of the dual connectivity configuration.

22. The method of claim 20 , wherein the signal indicating that the UE is to establish the connection with the second base station comprises a request for the UE to perform a handover procedure to the second base station, wherein the first base station is a source base station of the handover procedure, and the second base station is a target base station of the handover procedure.

23. The method of claim 14 , wherein transmitting the indication comprises transmitting, to the UE, a first message indicating that the UE is to establish a connection with the second base station, and the method further comprises:

receiving, from the UE, a second message indicating the second antenna array that the UE is to use to establish the connection with the second base station.

24. The method of claim 23 , wherein the second message indicates that the UE is to perform an initial access procedure with the second base station.

25. The method of claim 23 , wherein the second message indicates that the UE is to perform a handover procedure with the second base station.

26. The method of claim 14 , wherein transmitting the indication comprises:

transmitting, to the UE, a first signal indicating that the UE is to establish a connection with the second base station; and

transmitting, to the UE, a second signal indicating the second antenna array.

27. An apparatus for wireless communication at a user equipment (UE), comprising:

a processor,

memory in electronic communication with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

communicate with a first base station using a first antenna array of a plurality of antenna arrays of the UE;

receive, from the first base station, an indication that the UE is to use a second antenna array of the plurality of antenna arrays to transmit a random access signal; and

transmit, to the first base station or a second base station, the random access signal using the second antenna array based at least in part on the received indication.

28. The apparatus of claim 27 , wherein the instructions to receive the indication are executable by the processor to cause the apparatus to:

receive a control channel order that comprises the indication that the UE is to use the second antenna array to transmit the random access signal.

29. An apparatus for wireless communication at a first base station, comprising:

a processor,

memory in electronic communication with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

communicate with a user equipment (UE);

identify a plurality of antenna arrays of the UE, the plurality of antenna arrays comprising at least a first antenna array used to communicate with the first base station and a second antenna array; and

transmit, to the UE, an indication that the UE is to use the second antenna array to transmit a random access signal to the first base station or a second base station.

30. The apparatus of claim 29 , wherein the instructions are further executable by the processor to cause the apparatus to:

receive, from the UE based at least in part on the transmitted indication, the random access signal; and

transmit, to the UE in response to the received random access signal, a timing advance value for the second antenna array.