Directional synchronization in assisted millimeter wave systems

1. A method for wireless communication by a first base station (BS), comprising:

communicating with at least one user equipment (UE) in a first frequency band;

determining at least part of resources and configuration for the at least one UE for participating in at least one of an access or management procedure comprising an assisted directional initial access in a second frequency band; and

providing information about the resources and configuration allocated for the assisted directional initial access that differ from configuration and resources allocated for non-assisted directional initial access to the at least one UE for signaling to be transmitted as part of the access or management process.

2. The method of claim 1 , wherein:

the at least one of an access or management procedure further comprises at least one of: beam management, mobility management, radio resource management (RRM), or radio link monitoring (RLM); and

the signaling comprises at least one of a directional synchronization signal, a beam reference signal, a channel carrying at least part of a set of system information, or a random access message, wherein the directional synchronization signal comprises at least one of a primary synchronization (PSS), a secondary synchronization signal (SSS), a tertiary synchronization signal (TSS), a timing or frequency refinement signal (TRS), a demodulation reference signal (DMRS) for a synchronization channel.

3. The method of claim 1 , wherein:

the resources and configuration is for the at least one UE to use when participating in the at least one of an access or management procedure in the second frequency band with a second BS, and

the signaling comprises at least one of a directional synchronization signal, a beam reference signal, a channel carrying at least part of a set of system information, a second random access message to be transmitted by the second BS, or a first random access message to be transmitted by the at least one UE to the second BS.

4. The method of claim 3 , wherein:

the information comprises an indication to the at least one UE whether it can use timing of the first BS to acquire at least part of timing of the second BS.

5. The method of claim 3 , wherein:

the at least one of an access or management procedure comprises a contention-free random access procedure with the second BS.

6. The method of claim 1 , wherein:

the signaling comprises at least one of a directional synchronization signal, a beam reference signal, a channel carrying at least part of system information; and

the information comprises at least one of a transmission periodicity, a beam sweeping periodicity, time and frequency resources used for transmission of the signaling, one or more measurement windows to receive and measure a synchronization signal or a beam reference signal, a set of synchronization signals or beam reference signals to measure within a measurement window, an indication of actually transmitted synchronization signals, information regarding quasi-collocation of a synchronization signal or a beam reference signal with other signals or channels, an indication of synchronization signal repetition within a beam sweeping period, subcarrier spacing, a sequence generation parameter for a synchronization signal, or a beam reference signal.

7. The method of claim 1 , wherein:

the at least one of an access or management procedure comprises a random access procedure; and

the signaling comprises at least one of a first random access message to be transmitted by the at least one UE or a second random access message to be transmitted to the at least one UE.

8. The method of claim 7 , wherein the information comprises at least one of:

an indication of association between the resources of the at least one of a first random access message and a second random access message with a set of at least one or multiple of a synchronization signal and a beam reference signal;

a quasi-collocation (QCL) configuration with other signals and channels;

a set of dedicated resources and/or configuration for the at least one of a first random access message and a second random access message;

a subcarrier spacing, a preamble id, a cyclic shift, a power control parameter, a maximum number of retransmissions of the first random access message; or

a subcarrier spacing of the second random access message.

9. The method of claim 1 , wherein determining the at least part of resources and configuration is based at least on one of:

an indication from an upper layer, an indication from a network, an indication from a second BS, measurements of the first BS, a set of pre-determined configurations, an indication from the at least one UE including at least one of a measurement report, a request, or a capability indication of the UE.

10. The method of claim 1 , wherein providing the information to the at least one UE is based on transmitting at least one of:

a layer-1 signal, a media access control (MAC) control element (CE), a radio resource control (RRC) message, a broadcast channel, a control channel, or dedicated signaling.

11. The method of claim 1 , wherein:

the at least part of resources and configuration are specific to the at least one UE or a plurality of UEs including the at least one UE.

12. The method of claim 1 , wherein:

at least part of the second frequency band is non-overlapping with the first frequency band.

13. A method for wireless communication by a user equipment (UE), comprising:

communicating with a first base station (BS) in a first frequency band;

receiving, from the first B S, information of at least part of resources and configurations allocated for an assisted directional initial access that differ from configuration and resources allocated for non-assisted directional initial access for participating in at least one of an access or management procedure comprising the assisted directional initial access in a second frequency band, and

participating in at least one of an access or management procedures in the second frequency band.

14. The method of claim 13 , wherein:

the at least one of an access or management procedure further comprises at least one of beam management, mobility management, radio resource management (RRM), or radio link monitoring (RLM); and

the signaling comprises at least one of a directional synchronization signal including a primary synchronization (PSS), a secondary synchronization signal (SSS), a tertiary synchronization signal (TSS), a timing or frequency refinement signal (TRS), a demodulation reference signal (DMRS) for a synchronization channel, a beam reference signal, a channel carrying at least part of a set of system information, or a random access message.

15. The method of claim 13 , wherein:

the UE is configured to participate in the at least one of an access or management procedure in the second frequency band with a second BS; and

the signaling comprises at least one of a directional synchronization signal, a beam reference signal, a channel carrying at least part of a set of system information, a second random access message to be transmitted by the second BS, or a first random access message to be transmitted by the UE to the second BS.

16. The method of claim 15 , wherein:

information comprises an indication to the UE whether it can use timing of the first BS to acquire at least part of timing of the second BS.

17. The method of claim 15 , wherein the at least one of an access or management procedure comprises a contention-free random access procedure with the second BS.

18. The method of claim 15 , further comprising:

at least one of processing or measuring one or more of a synchronization signal, beam reference signals, or a synchronization channel from the second BS;

transmitting a signal to the first BS indicating a result of the processing or measuring.

19. The method of claim 18 , wherein the processing or measuring is based at least on the information received from the first BS.

20. The method of claim 18 , wherein:

the UE receives at least part of the information after transmitting the signal to the first BS.

21. The method of claim 13 , wherein:

the signaling comprises at least one of a directional synchronization signal, a beam reference signal, or a channel carrying at least part of system information; and

the information comprises at least one of a transmission periodicity, a beam sweeping periodicity, time and frequency resources used for transmission of the signaling, one or more measurement windows to receive and measure a synchronization signal or a beam reference signal, a set of synchronization signals or beam reference signals to measure within a measurement window, an indication of actually transmitted synchronization signals, information regarding quasi-collocation of a synchronization signal or a beam reference signal with other signals or channels, an indication of synchronization signal repetition within a beam sweeping period, subcarrier spacing, a sequence generation parameter for a synchronization signal, or a beam reference signal.

22. The method of claim 13 , wherein:

the at least one of an access or management procedure comprises a random access procedure; and

the signaling comprises at least one of a first random access message to be transmitted by the UE or a second random access message to be transmitted to the UE.

23. The method of claim 22 , wherein the information comprises at least one of:

an indication of association between the resources of the at least one of a first random access message and a second random access message with a set of at least one or multiple of a synchronization signal and a beam reference signal;

a QCL configuration with other signals and channels;

a set of dedicated resources and/or configuration for the at least one of a first random access message and a second random access message;

a subcarrier spacing, a preamble id, a cyclic shift, a power control parameter, a max number of retransmissions of the first random access message; or

a subcarrier spacing of the second random access message.

24. The method of claim 13 , further comprising:

transmitting, to the first B S, an indication including at least one of a measurement report of one or multiple of synchronization signals and beam reference signals, a set of one or more cell identifiers of at least one other detected base station, a request, or a capability of the UE.

25. The method of claim 13 , wherein the information is received from the first B S via at least one of:

a layer-1 signal, a media access control (MAC) control element (CE), a radio resource control (RRC) message, a broadcast channel, a control channel, or dedicated signaling.

26. The method of claim 13 , wherein:

the at least part of resources and configuration are specific to the UE or a plurality of UEs including the UE.

27. An apparatus for wireless communication by a first base station (BS), comprising:

means for communicating with at least one user equipment (UE) in a first frequency band;

means for determining at least part of resources and configuration for the at least one UE for participating in at least one of an access or management procedure comprising an assisted directional initial access in a second frequency band; and

means for providing information about the resources and configuration allocated for the assisted directional initial access that differ from configuration and resources allocated for non-assisted directional initial access to the at least one UE for signaling to be transmitted as part of the access or management process.

28. An apparatus for wireless communication by a user equipment (UE), comprising:

means for communicating with a first base station (BS) in a first frequency band;

means for receiving, from the first BS, information of at least part of resources and configurations allocated for an assisted directional initial access that differ from configuration and resources allocated for non-assisted directional initial access for participating in at least one of an access or management procedure comprising the assisted directional initial access in a second frequency band; and

means for participating in at least one of an access or management procedures in the second frequency band.