Methods and systems for generalized RACH-less mobility

Patent metadata

Field	Value
Publication number	US-10791533-B2
Application number	US-201916415910-A
Country	US
Kind code	B2
Filing date	May 17, 2019
Priority date	Jul 19, 2018
Publication date	Sep 29, 2020
Grant date	Sep 29, 2020

Abstract

In accordance to embodiments, a user equipment (UE) may receive, from the source base station, a beam information message comprising beam associated information. The beam associated information may indicate a plurality of beam identifiers (IDs) corresponding to a plurality of beams in the target base station and a plurality of default timing advance (TA)s. Each default TA of the plurality of TAs is associated with one beam of the plurality of beams in the target base station and additional related configurations.

First claim

What is claimed is:

1. A method for random-access channel (RACH)-less mobility from a source base station to a target base station, the method comprising:
receiving, by a user equipment (UE) from the source base station, a beam information message comprising beam associated information, the beam associated information indicating a plurality of beam identifiers (IDs) corresponding to a plurality of beams in the target base station, a plurality of default timing advance (TA) groups, and a plurality of additional related configuration sets, wherein each default TA group of the plurality of default TA groups is associated with a beam of the plurality of beams in the target base station and an additional related configuration set of the plurality of the additional related configuration sets; and
transmitting, to the target base station without performing random access by the UE to the target base station, an uplink (UL) transmission with a TA adjustment based on a target beam of the plurality of beams in which the UE is located and a first additional related configuration set of the plurality of additional related configuration sets, wherein the TA adjustment is based on a first default TA of a first default TA group associated with the target beam, and wherein the first additional related configuration set is associated with the first default TA.

2. The method of claim 1 , wherein the first default TA group associated with the target beam comprises a set of default TAs, and each one of the set of the default TAs corresponds to a beam in the source base station, the method further comprising:
determining, by the UE, the first default TA based on the target beam and a source beam in the source base station in which the UE is located and connected with the source base station.

3. The method of claim 1 , wherein the first default TA is the only TA in the first default TA group.

4. The method of claim 1 , wherein TAs in the plurality of default TA groups are obtained by the target base station by collecting previous TAs used in previous successful handovers.

5. The method of claim 1 , further comprising:
selecting, by the UE, the target beam from one or more candidate beams for access; and
determining, by the UE, the first default TA for RACH-less access in the target beam based on a beam ID associated with the target beam and the beam associated information in the beam information message.

6. The method of claim 1 , wherein the beam information message is transmitted based on RRC signaling or layer one (L1) signaling.

7. The method of claim 1 , wherein the beam information message comprises one of an RRC connection reconfiguration message configured as a handover (HO) command, or a PSCell activation message.

8. The method of claim 1 , wherein the first additional related configuration set comprises at least one of:
a cyclic prefix (CP) configuration, a UL transmission power configuration, a time-frequency UL transmission resource configuration, one or more demodulation reference signal (DMRS) configurations, or one or more modulation coding scheme (MCS) configurations.

9. The method of claim 1 , wherein a beam ID of the plurality of beam IDs is one of a SSB ID, or a channel state information (CSI)-reference signal (RS) ID.

10. A method for random-access channel (RACH)-less mobility from a source base station to a target base station, the method comprising:
transmitting, by the target base station to the source base station, beam associated information, the beam associated information indicating a plurality of beam identifiers (IDs) corresponding to a plurality of beams in the target base station, a plurality of default timing advance (TA) groups, and a plurality of additional related configuration sets, wherein each default TA group of the plurality of default TA groups is associated with a beam of the plurality of beams in the target base station and an additional related configuration set of the plurality of the additional related configuration sets; and
receiving, by the target base station from a user equipment (UE) without performing random access by the UE, an uplink (UL) transmission with a TA adjustment based on a target beam of the plurality of beams in which the UE is located and a first additional related configuration set of the plurality of additional related configuration sets, wherein the TA adjustment is based on a first default TA of a first default TA group associated with the target beam, and wherein the first additional related configuration set is associated with the first default TA.

11. The method of claim 10 , wherein the first default TA group associated with the target beam comprises a set of default TAs, and each one of the set of the default TAs corresponds to a beam in the source base station, and wherein the first default TA is determined based on the target beam and a source beam in the source base station in which the UE is located and connected with the source base station.

12. The method of claim 10 , wherein the first default TA is the only TA in the first default TA group.

13. The method of claim 10 , wherein TAs in the plurality of default TA groups are obtained by the target base station by collecting previous TAs used in previous successful handovers.

14. The method of claim 10 , wherein the UE selects the target beam from one or more candidate beams for access and determines a default TA for RACH-less access in the target beam based on a beam ID associated with the target beam and the beam associated information in a beam information message transmitted from the source base station to the UE.

15. The method of claim 10 , wherein a beam information message is transmitted from the source base station to the UE in one of a handover (HO) request acknowledgement message or a PSCell addition acknowledgement message to the source base station.

16. The method of claim 10 , wherein the first additional related configuration set comprises at least one of:
a cyclic prefix (CP) configuration, a UL transmission power configuration, a time-frequency UL transmission resource configuration, one or more demodulation reference signal (DMRS) configurations, or one or more modulation coding scheme (MCS) configurations.

17. The method of claim 10 , wherein a beam ID of the plurality of beam IDs is one of a SSB ID, or a channel state information (CSI)-reference signal (RS) ID.

18. A method for random-access channel (RACH)-less mobility from a source base station to a target base station, the method comprising:
receiving, by the source base station from the target base station, beam associated information, the beam associated information indicating a plurality of beam identifiers (IDs) corresponding to a plurality of beams in the target base station, a plurality of default timing advance (TA) groups, and a plurality of additional related configuration sets, wherein each default TA group of the plurality of default TA groups is associated with a beam of the plurality of beams in the target base station and an additional related configuration set of the plurality of the additional related configuration sets; and
transmitting, by the source base station to a user equipment (UE), a beam information message comprising the beam associated information, wherein the UE, without performing random access, transmits to the target base station, an uplink (UL) transmission with a TA adjustment based on a target beam of the plurality of beams in which the UE is located and a first additional related configuration set of the plurality of additional related configurat

Assignees

• Huawei Tech Co Ltd

Inventors

• Zou Jialin
• Lyu Yongxia
• Xu Hua
• Zhang Liqing
• Ma Jianglei

Classifications

• H04B7/06952

  Selecting one or more beams from a plurality of beams, e.g. beam training, management or sweeping · CPC title

• H04W36/0083

  Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists · CPC title

• H04W36/0069

  in case of dual connectivity, e.g. decoupled uplink/downlink · CPC title

• H04W36/00725

  Random access channel [RACH]-less handover · CPC title

• H04W56/0005

  synchronizing of arrival of multiple uplinks · CPC title