Mobility handover with multiple carriers

Abstract

In accordance with some implementations, a method is provided. The method includes receiving, by a user equipment (UE), a configuration from a serving cell group. The configuration indicates a first component carrier (CC) of the serving cell group, a second CC of the serving cell group, a first CC of a candidate cell group, a second CC of the candidate cell group, and a condition for triggering an event. The method further includes transmitting, by the UE, a measurement report to the serving cell group in response to an occurrence of the event based on the condition.

Description

MOBILITY HANDOVER WITH MULTIPLE CARRIERSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This patent application claims priority to U.S. Provisional Application No. 63 / 783,043, filed on April 3, 2025, and entitled “Mobility Handover with Multiple Carriers,” application of which is hereby incorporated by reference herein as if reproduced in its entirety.TECHNICAL FIELD

[0002] The present disclosure relates generally to methods, design, and apparatus for mobility handover of wireless communication, and, in particular embodiments, to system and design for enhancements of wireless communication networks with low layer triggered mobility handover.BACKGROUND

[0003] Mobility handover can be a procedure of transferring an ongoing communication session of a user equipment (UE) from one cell (e.g., serving cell) to another cell (e.g., target cell) in the UE connected state. In some instances, the primary motivation for mobility handover is to ensure the seamless connectivity and continuity of services for the user, especially while the user is moving. A basic mobility handover procedure (e.g., in a wireless communication system such as the fifth generation (5G) New Radio (NR)) can be based on the LTE (Long-Term Evolution) handover mechanism, in which the network / eNB (evolved NodeB) controls UE mobility based on UE measurement report(s). In the basic mobility handover procedure, a source base station (e.g., a next generation Node B (gNB or gNodeB)), can trigger a mobility handover by sending a handover request to a target gNB. After receiving an acknowledgement (ACK) from the target gNB, the source gNB can initiate the mobility handover by sending, to the UE, a handover command with the target cell configuration. The UE can access the target cell after the target cell configuration is applied by the UE.SUMMARY

[0004] Technical advantages are generally achieved, by implementations of this disclosure which describe methods, apparatus, and system.

[0005] According to a first aspect, a method is provided. The method includes: receiving, by a user equipment (UE), a configuration from a serving cell group. The configuration indicates a first component carrier (CC) of the serving cell group, a second CC of the serving cell group, a first CC of a candidate cell group, a second CC of theFW 6000755PCT02 -1-candidate cell group, and a condition for triggering an event. The condition is based on at least one of a channel quality metric of the first CC of the serving cell group, a channel quality metric of the second CC of the serving cell group, a channel quality metric of the first CC of the candidate cell group, or a channel quality metric of the second CC of the candidate cell group. The method further includes transmitting, by the UE, a measurement report to the serving cell group in response to an occurrence of the event based on the condition.

[0006] With reference to the first aspect, in some implementations, the method further comprises: evaluating whether the event occurs based on the at least one of the channel quality metric of the first CC of the serving cell group, the channel quality metric of the second CC of the serving cell group, the channel quality metric of the first CC of the candidate cell group, or the channel quality metric of the second CC of the candidate cell group; receiving a cell switching command from the serving cell group; and performing a cell switching from the serving cell group to the candidate cell group in response to receiving the cell switching command.

[0007] With reference to the first aspect, in some implementations, receiving the configuration comprises: receiving one or more radio resource control (RRC) messages. Each of the one or more RRC messages comprises at least a portion of the configuration.

[0008] With reference to the first aspect, in some implementations, the serving cell group comprises one or more serving cells, and the candidate cell group comprises one or more candidate cells.

[0009] With reference to the first aspect, in some implementations, the condition for triggering the event comprises: the channel quality metric of the first CC of the candidate cell group is larger than the channel quality metric of the first CC of the serving cell group by a first offset; and the channel quality metric of the second CC of the candidate cell group is larger than the channel quality metric of the first CC of the serving cell group by a second offset.

[0010] With reference to the first aspect, in some implementations, the condition for triggering the event comprises: a larger one of the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group is larger than the channel quality metric of the first CC of the serving cell group by a first offset; and a difference between the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group is equal to or smaller than a second offset.FW 6000755PCT02 -2-[oon] With reference to the first aspect, in some implementations, the condition for triggering the event comprises: the channel quality metric of the first CC of the candidate cell group is larger than a larger one of the channel quality metric of the first CC of the serving cell group and the channel quality metric of the second CC of the serving cell group by a first offset; and the channel quality metric of the second CC of the candidate cell group is larger than the larger one of the channel quality metric of the first CC of the serving cell group and the channel quality metric of the second CC of the serving cell group by a second offset.

[0012] With reference to the first aspect, in some implementations, the condition for triggering the event comprises: the channel quality metric of the first CC of the candidate cell group is larger than a first threshold; and the channel quality metric of the second CC of the candidate cell group is larger than a second threshold.

[0013] With reference to the first aspect, in some implementations, the condition for triggering the event comprises: a larger one of the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group is larger than a threshold; and a difference between the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group is equal to or smaller than a offset.

[0014] With reference to the first aspect, in some implementations, the condition for triggering the event comprises: the channel quality metric of the first CC of the serving cell group is smaller than a first threshold; the channel quality metric of the second CC of the serving cell group is smaller than a second threshold; the channel quality metric of the first CC of the candidate cell group is larger than a third threshold; and the channel quality metric of the second CC of the candidate cell group is larger than a fourth threshold.

[0015] With reference to the first aspect, in some implementations, the condition for triggering the event comprises: a larger one of the channel quality metric of the first CC of the serving cell group and the channel quality metric of the second CC of the serving cell group is smaller than a first threshold; and a larger one of the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group is larger than a second threshold.

[0016] With reference to the first aspect, in some implementations, the condition for triggering the event comprises: a larger one of the channel quality metric of the first CC of the serving cell group and the channel quality metric of the second CC of the serving cell group is smaller than a threshold.FW 6000755PCT02 -3-

[0017] With reference to the first aspect, in some implementations, the configuration further indicates one or more of: a first plurality of reference signals (RSs) associated with the first CC of the serving cell group and the second CC of the serving cell group; a second plurality of RSs associated with the first CC of the candidate cell group and the second CC of the candidate cell group; a first number of CCs, comprising the first CC and the second CC, from the serving cell group; or a second number of CCs, comprising the first CC and the second CC, from the candidate cell group.

[0018] With reference to the first aspect, in some implementations, the method further comprises: determining the channel quality metric of the first CC of the serving cell group and the channel quality metric of the second CC of the serving cell group based on measurements of the first plurality of RSs; and determining the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group based on measurements of the second plurality of RSs.

[0019] With reference to the first aspect, in some implementations, the measurement report indicates one or more RS received power (RSRP) values and one or more identifiers for one or more RSs in the first plurality of RSs and the second plurality of RSs.

[0020] With reference to the first aspect, in some implementations, the channel quality metric of the first CC of the serving cell group comprises a beam level channel quality metric or a CC level channel quality metric.

[0021] With reference to the first aspect, in some implementations, the configuration further indicates a time to trigger (TIT) period, and the method further comprises: determining that the event occurs in response to detecting that the condition for triggering the event is satisfied during the TTT period.

[0022] With reference to the first aspect, in some implementations, the configuration further indicates a threshold, and the method further comprises: selecting one or more reference signals (RSs) associated with the first CC of the serving cell group, the second CC of the serving cell group, the first CC of the candidate cell group, or the second CC of the candidate cell group based on the threshold.

[0023] With reference to the first aspect, in some implementations, transmitting the measurement report comprises: transmitting the measurement report via a physical uplink shared channel (PUSCH) or a physical uplink control channel (PUCCH).FW 6000755PCT02 -4-

[0024] According to a second aspect, a method is provided. The method includes: transmitting, by a serving cell group, a configuration to a UE. The configuration indicates a first CC of the serving cell group, a second CC of the serving cell group, a first CC of a candidate cell group, a second CC of the candidate cell group, and a condition for triggering an event. The condition is based on at least one of a channel quality metric of the first CC of the serving cell group, a channel quality metric of the second CC of the serving cell group, a channel quality metric of the first CC of the candidate cell group, or a channel quality metric of the second CC of the candidate cell group. The method further includes receiving, by the serving cell group, a measurement report from the UE in response to an occurrence of the event based on the condition.

[0025] With reference to the second aspect, in some implementations, the method further comprises: transmitting a cell switching command to the UE.

[0026] With reference to the second aspect, in some implementations, transmitting the cell switching command to the UE comprises transmitting the cell switching command to the UE in response to receiving the measurement report from the UE.

[0027] With reference to the second aspect, in some implementations, transmitting the configuration comprises: transmitting one or more RRC messages. Each of the one or more RRC messages comprises at least a portion of the configuration.

[0028] With reference to the second aspect, in some implementations, the serving cell group comprises one or more serving cells, and the candidate cell group comprises one or more candidate cells.

[0029] With reference to the second aspect, in some implementations, the condition for triggering the event comprises: the channel quality metric of the first CC of the candidate cell group is larger than the channel quality metric of the first CC of the serving cell group by a first offset; and the channel quality metric of the second CC of the candidate cell group is larger than the channel quality metric of the first CC of the serving cell group by a second offset.

[0030] With reference to the second aspect, in some implementations, the condition for triggering the event comprises: a larger one of the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group is larger than the channel quality metric of the first CC of the serving cell group by a first offset; and a difference between the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group is equal to or smaller than a second offset.FW 6000755PCT02 -5-

[0031] With reference to the second aspect, in some implementations, the condition for triggering the event comprises: the channel quality metric of the first CC of the candidate cell group is larger than a larger one of the channel quality metric of the first CC of the serving cell group and the channel quality metric of the second CC of the serving cell group by a first offset; and the channel quality metric of the second CC of the candidate cell group is larger than the larger one of the channel quality metric of the first CC of the serving cell group and the channel quality metric of the second CC of the serving cell group by a second offset.

[0032] With reference to the second aspect, in some implementations, the condition for triggering the event comprises: the channel quality metric of the first CC of the candidate cell group is larger than a first threshold; and the channel quality metric of the second CC of the candidate cell group is larger than a second threshold.

[0033] With reference to the second aspect, in some implementations, the condition for triggering the event comprises: a larger one of the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group is larger than a threshold; and a difference between the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group is equal to or smaller than a offset.

[0034] With reference to the second aspect, in some implementations, the condition for triggering the event comprises: the channel quality metric of the first CC of the serving cell group is smaller than a first threshold; the channel quality metric of the second CC of the serving cell group is smaller than a second threshold; the channel quality metric of the first CC of the candidate cell group is larger than a third threshold; and the channel quality metric of the second CC of the candidate cell group is larger than a fourth threshold.[OO35] With reference to the second aspect, in some implementations, the condition for triggering the event comprises: a larger one of the channel quality metric of the first CC of the serving cell group and the channel quality metric of the second CC of the serving cell group is smaller than a first threshold; and a larger one of the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group is larger than a second threshold.

[0036] With reference to the second aspect, in some implementations, the condition for triggering the event comprises: a larger one of the channel quality metric of the first CC of the serving cell group and the channel quality metric of the second CC of the serving cell group is smaller than a threshold.FW 6000755PCT02 -6-

[0037] With reference to the second aspect, in some implementations, the configuration further indicates one or more of: a first plurality of RSs associated with the first CC of the serving cell group and the second CC of the serving cell group; a second plurality of RSs associated with the first CC of the candidate cell group and the second CC of the candidate cell group; a first number of CCs, comprising the first CC and the second CC, from the serving cell group; or a second number of CCs, comprising the first CC and the second CC, from the candidate cell group.

[0038] With reference to the second aspect, in some implementations, the measurement report indicates one or more RSRP values and one or more identifiers for one or more RSs in the first plurality of RSs and the second plurality of RSs.

[0039] With reference to the second aspect, in some implementations, the channel quality metric of the first CC of the serving cell group comprises a beam level channel quality metric or a CC level channel quality metric.

[0040] With reference to the second aspect, in some implementations, the configuration further indicates a TTT period.

[0041] With reference to the second aspect, in some implementations, the configuration further indicates a threshold, and the UE selects one or more RSs associated with the first CC of the serving cell group, the second CC of the serving cell group, the first CC of the candidate cell group, or the second CC of the candidate cell group based on the threshold.

[0042] With reference to the second aspect, in some implementations, receiving the measurement report comprises: receiving the measurement report via a PUSCH or a PUCCH.

[0043] According to a third aspect, a method is provided. The method includes: receiving, by a UE, a configuration from a serving cell group. The configuration indicates at least a first timing advance group (TAG) of a candidate cell group and a plurality of CCs of the candidate cell group, and the plurality of CCs comprises at least a first CC associated with the first TAG. The method further includes transmitting, by the UE, a random access preamble to the candidate cell group for the first TAG.

[0044] With reference to the third aspect, in some implementations, the plurality of CCs further comprises a second CC associated with a second TAG of the candidate cell group. The method further comprises: receiving an indication from the serving cell group. The indication indicates a request for a first random access for the first TAG and a second random access for the second TAG. The indication further indicates the randomFW 6000755PCT02 -7-access preamble, a first random access resource for the first random access, and a second random access resource for the second random access.

[0045] With reference to the third aspect, in some implementations, the indication comprises at least one of a physical downlink control channel (PDCCH) order, downlink control information (DCI), or a medium access control (MAC)-control element (CE).

[0046] With reference to the third aspect, in some implementations, transmitting the random access preamble to the candidate cell group for the first TAG comprises, in response to receiving the indication: transmitting the random access preamble to the candidate cell group for the first TAG via the first random access resource; and transmitting the random access preamble to the candidate cell group for the second TAG via the second random access resource.

[0047] With reference to the third aspect, in some implementations, the first random access resource comprises one or more of: a first uplink / supplementary uplink (UL / SUL) carrier indicator, a first synchronization signal block (SS / PBCH) index, a first physical random access channel (PRACH) mask index, or a first PRACH retransmission indicator.

[0048] With reference to the third aspect, in some implementations, the second random access resource comprises one or more of: a second UL / SUL carrier indicator, a second SS / PBCH index, a second PRACH mask index, or a second PRACH retransmission indicator.

[0049] With reference to the third aspect, in some implementations, the configuration further indicates a condition for triggering a random access. The method further comprises: performing measurements on the plurality of CCs; and selecting the first CC from the plurality of CCs based on results of the measurements and the condition. The condition is satisfied on the first CC.

[0050] With reference to the third aspect, in some implementations, transmitting the random access preamble to the candidate cell group for the first TAG comprises: in response to selecting the first CC, transmitting the random access preamble to the candidate cell group for the first TAG.

[0051] With reference to the third aspect, in some implementations, the condition comprises: a first channel quality metric of one of the plurality of CCs of the candidate cell group is equal to or larger than a first threshold, and a second channel quality metric of a CC of the serving cell group is smaller than a second threshold; and the configuration comprises the first threshold and the second threshold.FW 6000755PCT02 -8-

[0052] With reference to the third aspect, in some implementations, the first channel quality metric is a reference signal received power (RSRP) or a signal-to-interference- plus-noise ratio (SINR).[OO53] With reference to the third aspect, in some implementations, receiving the configuration comprises: receiving one or more RRC messages. Each of the one or more RRC messages comprises at least a portion of the configuration.

[0054] With reference to the third aspect, in some implementations, the serving cell group comprises one or more serving cells. The candidate cell group comprises one or more candidate cells.

[0055] With reference to the third aspect, in some implementations, the method further comprises: receiving a response. The response confirms reception of the random access preamble.

[0056] With reference to the third aspect, in some implementations, receiving the response comprises: receiving one of a medium access control (MAC)-control element (CE), a group common PDCCH, or a random access response (RAR) command that comprises the response.

[0057] With reference to the third aspect, in some implementations, the response indicates at least one of: an index of the random access preamble; an identifier (ID) of the first TAG; or a first time advance (TA) value for the first TAG.

[0058] With reference to the third aspect, in some implementations, the plurality of CCs further comprises a second CC associated with a second TAG of the candidate cell group, and the response indicates a first TA value for the first TAG and a second TA value for the second TAG.

[0059] With reference to the third aspect, in some implementations, the plurality of CCs further comprises a second CC associated with a second TAG of the candidate cell group. The method further comprises: receiving a cell switching command from the serving cell group. The cell switching command indicates supplementary uplink carrier or uplink carrier for the first TAG, supplementary uplink carrier or uplink carrier for the second TAG, a first timing advance command for the first TAG, a second timing advance command for the second TAG, a first transmission configuration indicator (TCI) state ID for the first TAG, and a second TCI state ID for the second TAG.

[0060] According to a fourth aspect, a method is provided. The method includes: transmitting, by a serving cell group, a configuration to a UE. The configuration indicates at least a first TAG of a candidate cell group and a plurality of CCs of the candidate cellFW 6000755PCT02 -9-group, and the plurality of CCs comprises at least a first CC associated with the first TAG. The method further includes receiving, by the candidate cell group, a random access preamble from the UE for the first TAG.

[0061] With reference to the fourth aspect, in some implementations, the plurality of CCs further comprises a second CC associated with a second TAG of the candidate cell group. The method further comprises: transmitting, by the serving cell group, an indication to the UE. The indication indicates a request for a first random access for the first TAG and a second random access for the second TAG, and the indication further indicates the random access preamble, a first random access resource for the first random access, and a second random access resource for the second random access.

[0062] With reference to the fourth aspect, in some implementations, the indication comprises at least one of a PDGGH order, DGI, or a MAG-CE.

[0063] With reference to the fourth aspect, in some implementations, the first random access resource comprises one or more of: a first UL / SUL carrier indicator, a first synchronization signal block (SS / PBCH) index, a first PRACH mask index, or a first PRACH retransmission indicator.

[0064] With reference to the fourth aspect, in some implementations, the second random access resource comprises one or more of: a second UL / SUL indicator, a second SS / PBCH index, a second PRACH mask index, or a second PRACH retransmission indicator.

[0065] With reference to the fourth aspect, in some implementations, the configuration further indicates a condition for triggering a random access.

[0066] With reference to the fourth aspect, in some implementations, the condition comprises: a first channel quality metric of one of the plurality of CCs of the candidate cell group is equal to or larger than a first threshold, and a second channel quality metric of a CC of the serving cell group is smaller than a second threshold; and the configuration comprises the first threshold and the second threshold.

[0067] With reference to the fourth aspect, in some implementations, the first channel quality metric is a RSRP or a SINR.

[0068] With reference to the fourth aspect, in some implementations, transmitting the configuration comprises: transmitting one or more RRC messages. Each of the one or more RRC messages comprises at least a portion of the configuration.FW 6000755PCT02 -10-

[0069] With reference to the fourth aspect, in some implementations, the serving cell group comprises one or more serving cells, and the candidate cell group comprises one or more candidate cells.

[0070] With reference to the fourth aspect, in some implementations, the method further comprises: transmitting a response. The response confirms reception of the random access preamble.

[0071] With reference to the fourth aspect, in some implementations, transmitting the response comprises: transmitting one of a MAC-CE, a group common PDCCH, or a RAR command that comprises the response.

[0072] With reference to the fourth aspect, in some implementations, the response indicates at least one of: an index of the random access preamble; an ID of the first TAG; or a first TA value for the first TAG.

[0073] With reference to the fourth aspect, in some implementations, the plurality of CCs further comprises a second CC associated with a second TAG of the candidate cell group, and the response indicates a first TA value for the first TAG and a second TA value for the second TAG.

[0074] With reference to the fourth aspect, in some implementations, the plurality of CCs further comprises a second CC associated with a second TAG of the candidate cell group. The method further comprises: transmitting, by the serving cell group, a cell switching command to the UE. The cell switching command indicates supplementary uplink carrier or uplink carrier for the first TAG, supplementary uplink carrier or uplink carrier for the second TAG, a first timing advance command for the first TAG, a second timing advance command for the second TAG, a first transmission configuration indicator (TCI) state ID for the first TAG, and a second TCI state ID for the second TAG.

[0075] According to a fifth aspect, an apparatus is provided. The apparatus includes: at least one processor; and at least one memory coupled to the at least one processor, where the at least one memory stores programming instructions that, when executed by the at least one processor, cause the apparatus to perform a method according to the first aspect or one or more implementations of the first aspect.

[0076] According to a sixth aspect, a non-transitory computer readable storage medium is provided. The non-transitory computer readable storage medium stores programming instructions that, when executed by at least one processor, cause an apparatus to perform a method according to the first aspect or one or more implementations of the first aspect.FW 6000755PCT02 -11-

[0077] According to a seventh aspect, an apparatus is provided. The apparatus includes: at least one processor; and at least one memory coupled to the at least one processor, where the at least one memory stores programming instructions that, when executed by the at least one processor, cause the apparatus to perform a method according to the second aspect or one or more implementations of the second aspect.

[0078] According to an eighth aspect, a non-transitory computer readable storage medium is provided. The non-transitory computer readable storage medium stores programming instructions that, when executed by at least one processor, cause an apparatus to perform a method according to the second aspect or one or more implementations of the second aspect.

[0079] According to a ninth aspect, an apparatus is provided. The apparatus includes: at least one processor; and at least one memory coupled to the at least one processor, where the at least one memory stores programming instructions that, when executed by the at least one processor, cause the apparatus to perform a method according to the third aspect or one or more implementations of the third aspect.

[0080] According to a tenth aspect, a non-transitory computer readable storage medium is provided. The non-transitory computer readable storage medium stores programming instructions that, when executed by at least one processor, cause an apparatus to perform a method according to the third aspect or one or more implementations of the third aspect.

[0081] According to an eleventh aspect, an apparatus is provided. The apparatus includes: at least one processor; and at least one memory coupled to the at least one processor, where the at least one memory stores programming instructions that, when executed by the at least one processor, cause the apparatus to perform a method according to the fourth aspect or one or more implementations of the fourth aspect.

[0082] According to a twelfth aspect, a non-transitory computer readable storage medium is provided. The non-transitory computer readable storage medium stores programming instructions that, when executed by at least one processor, cause an apparatus to perform a method according to the fourth aspect or one or more implementations of the fourth aspect.BRIEF DESCRIPTION OF THE DRAWINGS

[0083] For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:FW 6000755PCT02 -12-

[0084] FIG. 1 illustrates a diagram of a mobility handover (HO) procedure when multiple component carriers (CCs) are supported before and after HO, in accordance with some implementations of the present disclosure;

[0085] FIG. 2 illustrates a diagram of a mobility HO procedure when multiple CCs are supported in serving cells and candidate cells, in accordance with some implementations of the present disclosure;

[0086] FIG. 3 illustrates a diagram of a mobility HO procedure when multiple CCs are supported in a serving cell group and a candidate cell group, in accordance with some implementations of the present disclosure;

[0087] FIG. 4 illustrates a measurement report format when differential Li-reference signal received power (RSRP) and / or Li-signal-to-interference-plus-noise ratio (SINR) value are supported by the measurement report, in accordance with some implementations of the present disclosure;

[0088] FIG. 5 illustrates a structure of a medium access control control element (MAC CE) for activating or deactivating a cell, in accordance with some implementations of the present disclosure;

[0089] FIG. 6 illustrates a diagram of a mobility HO procedure when multiple CCs are supported in a serving cell group and a candidate cell group, in accordance with some implementations of the present disclosure;

[0090] FIG. 7 illustrates a diagram of a mobility HO procedure when multiple CCs are supported in a serving cell group and a candidate cell group, in accordance with some implementations of the present disclosure;

[0091] FIG. 8 illustrates a diagram of a mobility HO procedure when multiple CCs are supported in a serving cell group and a candidate cell group, in accordance with some implementations of the present disclosure;

[0092] FIG. 9 illustrates a diagram of a random access (RA) procedure when multiple timing advance groups (TAGs) are supported in candidate cells or candidate cell groups, in accordance with some implementations of the present disclosure;

[0093] FIG. 10 illustrates a format of a physical downlink control channel (PDCCH) order to trigger random access for multiple TAGs in candidate cell(s), in accordance with some implementations of the present disclosure;FW 6000755PCT02 -13-

[0094] FIG. 11 illustrates a diagram of a RA procedure when multiple CCs with multiple TAGs are supported in candidate cell(s), in accordance with some implementations of the present disclosure;

[0095] FIG. 12 illustrates an example cell switching command (CSC) when multiple CCs with multiple TAGs are supported in candidate cell(s), in accordance with some implementations of the present disclosure;

[0096] FIG. 13 illustrates a diagram of a mobility HO procedure when multiple CCs are supported in a serving cell group and a candidate cell group, in accordance with some implementations of the present disclosure;

[0097] FIG. 14 illustrates an example communications system in which some embodiments can be implemented, in accordance with some implementations of the present disclosure;

[0098] FIG. 15 illustrates another example communication system in which some embodiments discussed herein can be implemented, in accordance with some implementations of the present disclosure;

[0099] FIGS. 16A and 16B illustrate example devices that can implement some embodiments discussed herein, in accordance with some implementations of the present disclosure; and

[0100] FIG. 17 is a block diagram of a computing system that can be used for implementing the devices and methods disclosed herein, in accordance with some implementations of the present disclosure.

[0101] Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.DETAILED DESCRIPTIONS

[0102] In the 5G-NR high frequency range (e.g., millimeter wave (mmWave) frequencies) with beamforming, when the UE moves or rotates, the UE can experience severe signal degradation. The channel conditions between line of sight (LOS) and non- LOS in 5G-NR can be much different, and the size of cells can also become much smaller due to increased propagation pathloss in the high frequency range. It can result in a higher handover failure rate, since the UE may not receive, before moving into a neighbor cell, the expected radio resource control (RRC) messages (generally a large size packet) to trigger a handover due to poor signal conditions or the UE quickly moving out of the serving cell. To reduce the handover failure rate, Conditional Handover (CHO) wasFW 6000755PCT02 -14-introduced to improve the reliability of handovers in Release 16 for 5G-NR. CHO is a mobility handover procedure that is executed only when the configured CHO execution condition(s) are met. The UE can maintain a connection with a source gNB after receiving a CHO configuration and can start evaluating the CHO execution conditions for the candidate cell(s). If at least one CHO candidate cell satisfies the corresponding CHO execution condition, the CHO can be executed by the UE detaching from the source gNB, the UE applying the corresponding configuration for the selected candidate cell, and the UE accessing the target cell.

[0103] Even though CHO can improve the performance of mobility handover in terms of low handover failure rate and low latency, some issues still exist and need to be further addressed. For example, the evaluation of CHO execution condition is based on Layer 3 (L3) measurements, such as L3 reference signal received power (RSRP) and / or L3 signal -to-interference-plus-noise ratio (SINR). Additionally, UE can perform downlink synchronization (e.g., cell search by detecting synchronization signal blocks) and uplink synchronization (e.g., random access procedure for timing advance acquisition) to the target cell after applying the corresponding configuration of the target cell and meeting CHO execution conditions. Furthermore, CHO can require reconfiguration of upper layers (e.g., RRC or Packet Data Convergence Protocol (PDCP)) and / or resetting of lower layer parameters (e.g., Medium Access Control (MAC) and / or Physical (PHY)) after CHO execution conditions are met. All these issues still lead to longer latency, larger overhead, and longer interruption time than beam switch.

[0104] In Release 18 of 5G-NR, layer 1 (Li) / layer 2 (L2) triggered mobility, also known as lower-layer triggered mobility (LTM), was introduced to enable a UE to change its serving cell via L1 / L2 signaling, while keeping configuration of the upper layers and / or minimizing changes of configuration of the lower layers and supporting early synchronizations to the target cell including downlink and uplink. This significantly helps reduce latency, overhead and interruption time during mobility handover in 5G-NR. Release 18 LTM supports both intra-distributed unit (DU) and intra-centralized unit (CU)-inter-DU mobility handovers. Release 18 LTM also supports both intra-frequency and inter-frequency mobility handovers. During Release 18 LTM, the user plane is continued whenever possible (e.g., intra-DU and inter-DU), without resetting or by minimizing changes of configuration of the lower layers of the target cell, to avoid data loss and the additional delay of data recovery.

[0105] In Release 19 of 5G-NR, the enhancements for LTM mainly focus on inter-CU handover (HO) and reducing measurement signaling overhead based on event triggered measurement report. LTM can offer improvements in handover latency and interruptionFW 6000755PCT02 -15-time compared to Layer 3 based mobility. However, LTM as introduced in Release 18 also has several limitations compared to Layer 3 mobility. LTM operation is only supported for mobility between cells of the same gNB (same CU) in Release 18 of 5G-NR. Depending on the deployment of the network, this can significantly limit the opportunities to use LTM. By enabling LTM operation between cells of different gNBs (i.e., inter-CU) as in Release 19, the network can gain the benefits of LTM for more deployment scenarios. In addition, Layer 3 mobility uses layer 3 measurement reporting which supports UE evaluated events for triggering measurement reports and reduces signaling overhead compared to periodic measurement reporting. Such event triggering measurement reporting is also supported by the Li measurements that are used for LTM mobility in Release 19.

[0106] As aforementioned, handover mobility and enhancements so far from Rel-15 to Rel-19 of 5G NR mainly focus on reliability, latency, interruption time and signaling overhead for measurement report. However, when carrier aggregation (CA) is configured and supported for both serving cell and candidate cell(s), only one carrier / cell is activated during mobility handover (HO) based on current mobility handover enhancements, which could dramatically reduce the bandwidth of UE connections during HO and can have significant impacts on performances of high data rate and low latency services in the CA (e.g., with multiple carriers) case, such as for extended reality (XR), immersive / holographic communication, etc. Thus, the current mobility handover in the CA case needs to be further enhanced to support wide bandwidth requirements and high data rate during HO for future immersive / holographic communications and / or the like.

[0107] The techniques described in this application provide methods and systems that enable a UE to evaluate channel quality across multiple CCs of a serving cell group and a candidate cell group, for example, during a lower-layer triggered mobility (LTM) process. Measurement reports from the UE can be triggered when conditions across those multiple carriers jointly satisfy defined criteria. By conditioning measurement reporting on the quality of multiple CCs jointly, the network can obtain the information needed to command a simultaneous multi-carrier cell switch in a single step, thereby eliminating the sequential handover latency and reducing overhead and interruption time during mobility handover.

[0108] In addition, the present application provides methods and systems that address the signaling overhead associated with early random access procedures when the candidate cell group’s multiple CCs are distributed across different timing advance groups. For example, in some embodiments, an enhanced PDCCH order format isFW 6000755PCT02 -16-introduced, which can consolidate random access parameters for multiple TAGs into a single indication. This method can substantially reduce physical-layer signaling overhead while enabling the UE to perform uplink synchronization to multiple TAGs of the candidate cell group before cell switching. Some embodiments of the application also provide a conditional, autonomous early random access procedure. The UE can evaluate measurements against configured thresholds and initiate random access to the appropriate TAG without requiring a network-triggered PDCCII order. These mechanisms can help preserve the wideband capacity needed for a communication system (e.g., next generation communication system) while reducing both handover latency and control-plane signaling overhead.

[0109] The following example embodiments in disclosure can be combined or split to generate one or more new embodiments. All the procedures, elements, terms, behaviors, and / or the like described in an embodiment can be applied to (or combined with) one or more other embodiments to become one or more new embodiments. In this disclosure, “a” and “an” and similar phrases are to be interpreted as “at least one” and “one or more.” Similarly, any term that ends with the suffix “(s)” is to be interpreted as “at least one” and “one or more.” In this disclosure, the term “may” is to be interpreted as “may, for example.” In other words, the term “may” is indicative that the phrase following the term “may” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments.

[0110] FIG. 1 illustrates a diagram of an example embodiment for a procedure of mobility handover (HO) when multiple component carriers (CCs) are supported before and after HO, in accordance with some implementations of the present disclosure. As aforementioned, event triggered measurement report can be supported by the Li measurements (e.g., L1-RSRP and / or L1-SINR) that are used for LTM mobility (for example, in Release 19 of 5G-NR). A serving cell group can be configured with carrier aggregation (CA) with multiple CCs. For example, the serving cell group can comprise a primary CC (PCC) (e.g., PCC_o as shown in FIG. 1) and two secondary CCs (SCCs) (e.g., SCC_Si and SCC_S2 as shown in FIG. 1). A target cell group can also be configured with CA with multiple CCs. For example, the target cell group can comprise a primary CC (PCC) (e.g., PCC_i as shown in FIG. 1) and two secondary CCs (SCCs) (e.g., SCC_Ci and SCC_C2 as shown in FIG. 1). In some embodiments, the term “primary” can be replaced with the term “anchor” in future releases (e.g., in 6G and beyond). In some embodiments, the term “secondary” can be replaced with the term “non-anchor” in future releases. The “CC” can also be used to refer to a BWP or in general, a fraction of the whole system bandwidth, such as a sub band, a group of PRBs, a group of BWPs, aFW 6000755PCT02 -17-group of sub bands, and / or the like. In an example, the configuration of CA for the target cell group can be performed by a network (NW) to UE via a serving cell (e.g., Base Station o (BSo) or gNBo as shown in FIG. i) from the serving cell group before UE’s cell switching from the serving cell to the target cell. In an example, the configuration of CA for the target cell group can be performed by NW to UE via the target cell (e.g., BSi or gNBi as shown in FIG. i) after the UE’s cell switching from the serving cell to the target cell.[out] In some embodiments, a serving cell group can include one or more serving cells. The serving cell group can be controlled or operated by a serving base station. A target cell group (also referred to as a candidate cell group) can include one or more target cells (or candidate cells). The candidate cell group can be controlled or operated by a target base station. For example, as shown in FIG. i, the serving cell group includes a Primary Cell (PCell) on PCC_o and two Secondary Cells (SCells) on SCC_Si and SCC_S2 respectively. The PCell and SCells in the serving cell group can be controlled by the serving base station BSo. The target cell group includes a PCell on PCC_i and two SCells on SCC_Ci and SCC_C2 respectively. The PCell and SCells in the target cell group can be controlled by the target base station BSi. In some embodiments, a person of ordinary skill in the art would understand that a serving cell group (or a serving cell) performing an action or an operation can be interpreted as the serving base station that controls the one or more serving cells of the serving cell group performing the action or operation. In some embodiments, a target or candidate cell group (or a target cell) performing an action or an operation can be interpreted as the target base station that controls the one or more target or candidate cells of the target cell group performing the action or operation.

[0112] In existing technologies, UE can perform event evaluations just based on PCC_o of the serving cell group and / or PCC_t of the target cell group. The UE can transmit a measurement report to the serving cell in response to an event being fulfilled according to defined criteria. If the UE receives a cell switching command (e.g., a MAC CE) from the serving cell, the UE can perform cell switching from the serving cell to the target cell. During the serving cell switch, the CCs associated with the source serving cell, e.g., SCC_Si and SCC_S2, and their corresponding serving cells, e.g., SCelli and SCell2, can be released. After the UE performs cell switching from the serving cell to the target cell, the UE can receive, from the target cell, a secondary cell (SCell) addition command in radio resource control (RRC) configuration signaling to add two SCCs (e.g., SCC_Ci and SCC_C2) for the UE. In an example, the RRC configuration signaling can also include SCell activation / deactivation command to activate the two SCCs (SCC_Ci andFW 6000755PCT02 -18-SCC_C2) for the UE (e.g., via the field sCellState being set as ‘activated’). In an example, the RRC configuration signaling may not include SCell activation / deactivation command in the RRC configuration signaling but being followed by a MAC CE SCell activation / deactivation command. After that, UE can perform downlink receptions and / or uplink transmissions based on the multiple CCs of the target cell group (e.g., PCC_i, SCC_Ci and SCC_C2).

[0113] However, in some embodiments, operation over a wide bandwidth cannot be guaranteed during mobility HO based on the existing techniques since only one CC (PCC_o and PCC_i) is activated during mobility HO for the serving group and target cell group, respectively. Meanwhile, the SCCs (SCC_Si and SCC_S2) of the serving cell group can be deactivated / released before mobility HO and the SCCs (SCC_Ci and SCC_C2) of the target cell group can be activated after mobility HO. This could have a significant impact on the performance of high data rate and low latency services in the CA (e.g., multiple CCs) case, such as for Extended reality (XR), immersive / holographic communication, etc. Therefore, there is a need to enhance the existing technologies to support multiple activated CCs during mobility HO if CA is configured for both the serving cell group and target cell group. Furthermore, if a serving cell and / or a target cell (or candidate cell) is configured with multiple CCs in future releases (e.g., in 6G and beyond), multiple activated CCs during mobility HO may also need to be supported. In some embodiments, to enable multi-carrier handover, one key issue is how to define measurement events for multi-carrier-based measurement report and the related designs. In addition, the signaling overhead is also high based on the existing mechanism to trigger multiple early random accesses (RAs) with multiple timing advance groups (TAGs) in the CA case for one or more candidate cells (or cell groups) comprising target cell groups (e.g., a respective physical downlink control channel (PDCCH) order can be used to trigger an early RA for an individual TAG of each candidate cell or cell group). In that regard, another key issue is how to reduce signaling overhead associated with triggering multiple early RAs with multiple TAGs in the CA case with multiple CCs for one or more candidate cells (or cell groups).

[0114] FIG. 2 illustrates a diagram of an example embodiment for a procedure 200 of mobility HO when multiple CCs are supported in serving cell(s) and candidate cell(s), in accordance with some implementations of the present disclosure. During the procedure 200 of mobility HO, at 202, a UE can receive reference signal(s) (RS(s)) from multiple CCs of one or more candidate cells. In an example, the RS(s) can be configured (to the UE via RRC messages from the serving cell(s)) to be associated with the multiple CCs of the one or more candidate cells. The RS(s) can be one or more synchronization signalFW 6000755PCT02 -19-blocks (SSBs). The RS(s) can be one or more channel state information RSs (CSI-RSs). At 204, based on the measurements of the RS(s) transmitted from (or associated with) the multiple CCs of the one or more candidate cells, the UE can transmit, via a serving cell to NW, beam measurement report(s) of the multiple CCs of the one or more candidate cells (or cell groups) in response to an event being triggered. The event can be evaluated based on measurements of the multiple CCs of the one or more candidate cells (or cell groups) and / or one or more CCs of the serving cell (or cell group). In some embodiments, the measurement report format is defined based on at least measurements of the multiple CCs of the one or more candidate cells (or cell groups). In an example, at 206, based on indication of a PDCCH order, the UE performs RA(s) to one or more TAGs of candidate cell(s). In an example, based on conditional measurement of one or more of the RS(s) from the multiple CCs of the one or more candidate cells (or cell groups), the UE performs RA(s) to one or more TAGs of candidate cell(s) (or cell groups). At 208, the UE can perform HO (or cell switching) to a candidate cell (e.g., target cell) (or cell group) with multiple CCs in response to receiving a cell switch command (CSC) from the NW.

[0115] Regarding the event definitions based on the multiple CCs of the one or more candidate cells (or cell groups) and one or more CCs of serving cell(s) (or cell group), in the following description, as an example, it is assumed that serving cell(s) (or serving cell group) have two CCs: Si and S2, and Si is a primary CC (PCC) (or anchor CC) of the serving cell(s) (or serving cell group), S2 is secondary CC (SCC) of serving cell(s) (or serving cell group). As an example, it is also assumed that candidate cell(s) (or cell group) have two CCs: Ci and C2. Ci can be a PCC (or an anchor CC or a first CC) of the candidate cell(s) (or cell group), and C2 can be a SCC (or a non-anchor CC or a second CC) of the candidate cell(s) (or cell group) (e.g., CA is configured by NW via the serving cell with RRC messages before cell switching from serving cell to target cell (or candidate cell)). In addition, it is straightforward to extend these examples for event definitions to other cases, where serving cell(s) (or serving cell group) have more than two CCs (e.g., Si, S2, S3, etc.) and / or candidate cell(s) (or candidate cell group) have more than two CCs (e.g., Ci, C2, C3, etc.).

[0116] FIG. 3 illustrates a diagram of an example embodiment for a procedure of mobility HO when multiple CCs are supported in a serving cell (or a serving cell group) and candidate cell(s) (or candidate cell group), in accordance with some implementations of the present disclosure. A serving cell (or a serving cell group) can be configured with CA with multiple CCs. For example, as shown in FIG. 3, the serving cell (or the serving cell group) can comprise a PCC (PCC_Si) (also referred to as an anchor CC) and a SCC (SCC_S2). A UE can receive, from a NW (e.g., BS or gNB) via the servingFW 6000755PCT02 -20-cell, one or more RRC messages comprising configuration parameters indicating one or more candidate cells (or candidate cell groups) (e.g., Candidate Cell or Cell Group_o, Candidate Cell or Cell Group _i, and Candidate Cell or Cell Group_2). In some embodiments, the UE can receive a configuration from the serving cell group (e.g., a serving base station that controls one or more serving cells of the serving cell group), and the configuration can include the configuration parameters. Each of the one or more RRC messages can include at least a portion of the configuration. The configuration parameters can also indicate the PCC (PCC_Si or Si) and the SCC (SCC_S2 or S2) for serving cell or serving cell group. Each of the one or more candidate cells (or cell groups) can have two CCs, as aforementioned assumption. For example, the Candidate Cell or Cell Group_o can be configured with (or can have) CC_Ci (or Ci) and CC_C2 (or C2). The configuration of CA for candidate cell(s) can be performed by the NW to the UE via the serving cell before the UE’s cell switching from the serving cell to the candidate cell. CC_Ci (or Ci) can be a PCC (or anchor CC) of candidate (or target) cell (or cell group) (e.g., Candidate Cell or Cell Group_o) and CC_C2 (or C2) can be a SCC of candidate (or target) cell (or cell group) (e.g., Candidate Cell or Cell Group_o). In some embodiments, the serving cells (e.g., PCell on PCC_Si and SCell on SCC_S2) in the serving cell group can be controlled by a serving base station of FIG. 3. The candidate cells (e.g., PCell on CC_Ci and SCell on CC_C2) in the candidate cell group can be controlled by a candidate base station of FIG. 3. In some embodiments, the serving cell group (or a serving cell) performing an action or an operation can be interpreted as the serving base station that controls the one or more serving cells of the serving cell group performing the action or operation. In some embodiments, a candidate cell group (or a candidate cell) performing an action or an operation can be interpreted as the candidate base station that controls the one or more candidate cells of the candidate cell group performing the action or operation. A serving cell, serving cell group, or serving base station can also be referred to as a source cell, a source cell group, or a source base station. A candidate cell, candidate cell group, or candidate base station can also be referred to as a target cell, a target cell group, or a target base station. Based on the measurements (e.g., Li-RSRP and / or L1-SINR values) of the RS(s) transmitted from (or associated with) multiple CCs of the one or more candidate cells (or candidate cell groups), the UE can transmit measurement reports of the multiple CCs of the one or more candidate cells (or candidate cell group) in response to an event being triggered. The events (such as Event 1, Event 2, Event 3, Event 4, Event 5, Event 6, Event 7, and / or Event 8) can be defined based on measurements of RS(s) transmitted from multiple CCs of the one or more candidate cells (or candidate cell group) and / or from one or more CCs of the serving cell (or serving cell group) as the following:FW 6000755PCT02 -21-

[0117] In some embodiments, Event i can be defined as: the quality of Ci becomes amount of offseti better than that of Si, and the quality of C2 becomes an amount of offset2 better than that of Si. In some cases, e.g., when Ci and C2 are in the same band or with a small frequency difference, offseti can be equal to offset2. In that regard, only one offset value is needed. In some other cases, e.g., when Ci and C2 are in different bands or with a large frequency difference, offseti can be different from the offset2. In this case, based on existing technologies, both Ci and C2 can be eligible for cell switching, but the switching can be performed in a sequential way to candidate cell, resulting in long latency and bandwidth bottleneck during HO. For example, the UE can deactivate S2 first, and then perform cell switching from Si to Cl. In the next step, the UE can further perform cell switching to C2, which could result in veiy long latency for multiple-carrier HO and bandwidth bottleneck during HO because of the sequential HO for multiple carriers of candidate cell(s). However, this Event 1 can enable the UE to switch to both CCs (or multiple CCs) of candidate cell in one step (or at the same time), which can significantly reduce HO latency and increase bandwidth during HO supported by multiple active carriers of candidate cell(s). Here, the one step (or at the same time) can mean that the UE switches to both CCs (or multiple CCs) of candidate cell just based on a same HO command or a same cell switching command / condition. In addition, during the cell switching or HO procedures based on the one step (or at the same time), both CCs (or multiple CCs) of candidate cell can have different CC switching latency or a same CC switching latency. This definition of one step (or at the same time) can also be applied to other Events (such as Event 2 through Event 7 if applicable). In addition, for referencing convenience purpose, Event 1 can also be indicated as “the qualities of both Ci and C2 become an amount of offset better than that of Si”. The configuration parameters can indicate offseti and / or offset2.

[0118] In some embodiments, Event 2 can be defined as: the better quality of Ci and C2 becomes an amount of an offset value better than that of Si, and the difference between the qualities of Ci and C2 is less than a threshold. In this case, based on existing criteria, only one of Ci and C2 is eligible for cell switching. This event can enable the other CC to become eligible for cell switching if its quality is within a threshold from the better CC. This Event 2 can enable UE to switch to both CCs of candidate cell in one step (or at the same time) if the difference between the qualities of Ci and C2 is less than the threshold. In addition, for referencing convenience purpose, Event 2 can also be indicated as “the best quality of Ci and C2 becomes amount of an offset value better than that of Si”. The configuration parameters can indicate the offset value and / or the threshold.FW 6000755PCT02 -22-

[0119] In some embodiments, Event 3 can be defined as: the quality of Ci becomes an amount of offseti better than the better quality of Si and S2, and the quality of C2 becomes an amount of offset2 better than the better quality of Si and S2. In some cases, e.g., when Ci and C2 are in the same band or with a small frequency difference, offseti can be equal to offset2. In that regard, only one offset value is needed. In some other cases, e.g., when Ci and C2 are in different bands or with a large frequency difference, offseti can be different from offset2. In this case, based on existing criteria, both Ci and C2 are eligible for cell switching, but the switching must be performed in a sequential way to candidate cell, resulting in long latency and bandwidth bottleneck during HO. This Event 3 can enable the UE to switch to both CCs of candidate cell in one step (or at the same time). In addition, for referencing convenience purpose, Event 3 can also be indicated as “the quality of both Ci and C2 becomes an amount of offset value better than that of the best / better of Si and S2”. The configuration parameters can indicate offseti and / or offset2.

[0120] In some embodiments, Event 1, Event 2, and Event 3 can be used to enable the UE to perform measurement reporting for the NW to trigger cell switching from serving cell(s) to candidate cell(s) with multiple CCs.

[0121] In some embodiments, Event 4 can be defined as: the quality of Ci becomes better than absolute thresholdi, and the quality of C2 becomes better than absolute threshold2. In some cases, e.g., when Ci and C2 are in the same band or with a small frequency difference, thresholdi can be equal to threshold2. In that regard, only one threshold value is needed. In some other cases, e.g., when Ci and C2 are in different bands or with a large frequency difference, thresholdi can be different from threshold2. In this case, based on existing criteria, both Ci and C2 are eligible for cell switching, but the switching must be performed in a sequential way to candidate cell, resulting in long latency and bandwidth bottleneck during HO. This Event 4 can enable the UE to switch to both CCs of candidate cell in one step (or at the same time). In addition, for referencing convenience purpose, Event 4 can also be indicated as “the quality of both Ci and C2 becomes better than an absolute threshold”. The configuration parameters can indicate thresholdi and / or threshold2.

[0122] In some embodiments, Event 5 can be defined as: the better quality of Ci and C2 becomes better than an absolute threshold, and the difference between the qualities of Ci and C2 is less than a second threshold. In this case, based on existing criteria, both Ci and C2 are eligible for cell switching, but the switching must be performed in a sequential way to candidate cell resulting in long latency and bandwidth bottleneck during HO. This Event 5 can enable the UE to switch to both CCs of candidate cell in oneFW 6000755PCT02 -23-step (or at the same time). In addition, for referencing convenience purpose, Event 5 can also be indicated as “best quality of Ci and C2 is better than an absolute threshold, and the difference between the qualities of Ci and C2 is less than a threshold”. The configuration parameters can indicate the absolute threshold and / or the second threshold.

[0123] In some embodiments, Event 4 and Event 5 can be used to enable UE measurement reporting for the NW to trigger cell switching from serving cell(s) to candidate cell(s) with multi-carriers, such as for load balancing purposes between serving cell(s) and candidate cell(s).

[0124] In some embodiments, Event 6 can be defined as: the quality of Si becomes worse than absolute thresholdi, the quality of S2 becomes worse than absolute threshold2, the quality of Ci becomes better than absolute thresholds, and the quality of C2 becomes better than absolute thresholdq. In some cases, e.g., when Si and S2 are in the same band or with a small frequency difference, thresholdi can be equal to threshold2. In that regard, only one threshold value is needed. In some other cases, e.g., when Si and S2 are in different bands or with a large frequency difference, thresholdi can be different from the threshold2. Similarly, in some cases, e.g., when Ci and C2 are in the same band or with a small frequency difference, thresholds can be equal to thresholdq. In that regard, only one threshold value is needed. In some other cases, e.g., when Ci and C2 are in different bands or with a large frequency difference, thresholds can be different from the thresholdq. In this case, based on existing criteria, both Ci and C2 are eligible for cell switching, but the switching must be performed in a sequential way to candidate cell with long latency and bandwidth bottleneck during HO. This Event 6 can enable UE to switch to both CCs of candidate cell in one step (or at the same time). In addition, for referencing convenience purpose, Event 6 can also be indicated as “the quality of both Si and S2 are worse than absolute thresholdi and the quality of both Ci and C2 are better than absolute threshold2”. The configuration parameters can indicate the thresholdi, threshold2, thresholds, and / or thresholdq.

[0125] In some embodiments, Event 7 can be defined as: the better quality of Ci and C2 becomes better than absolute thresholdi, the better quality of Si and S2 becomes worse than absolute threshold2, and the difference between the qualities of Ci and C2 is less than a threshold. In this case, based on existing criteria, both Ci and C2 are eligible for cell switching, but the switching must be performed in a sequential way to candidate cell, resulting in long latency and bandwidth bottleneck during HO. This Event 7 can enable the UE to switch to both CCs of candidate cell in one step (or at the same time). In addition, for referencing convenience purpose, Event 7 can also be indicated as “betterFW 6000755PCT02 -24-quality of Ci and C2 is better than absolute thresholdi and better quality of Si and S2 is worse than absolute threshold2”. The configuration parameters can indicate the absolute thresholdi, the absolute threshold2, and / or the threshold.

[0126] In some embodiments, Event 6, and Event 7 can be used to enable UE measurement reporting for the NW to trigger cell switching from serving cell(s) to candidate cell(s) with multiple CCs if the requirements of relative channel quality between serving cell(s) and candidate cell(s) are not satisfied, e.g., as described in Event 1, Event 2, and Event 3.

[0127] In some embodiments, Event 8 can be defined as: the better quality of Si and S2 becomes worse than an absolute threshold. In addition, for referencing convenience purpose, Event 8 can be also indicated as “better quality of Si and S2 is worse than an absolute threshold”. Event 8 can be used to enable UE measurement report for NW to pre-alarm (or alert) poor serving cell quality. The configuration parameters can indicate the absolute threshold.

[0128] In some embodiments, the comparison during event evaluation for qualities of different CCs of serving cell(s) and / or candidate cell(s) for different events (e.g., Event 1, Event 2, Event 3, Event 4, Event 5, Event 6, Event 7, and Event 8) can comprise CC level quality comparison and / or beam level quality comparison. The CC level quality or the beam level quality can be a channel quality metric associated with the CC or the Beam. For CC level quality comparison, CC level quality for each CC of serving cell(s) and / or candidate cell(s) can be based on linear power scale average of L Li-RSRP (and / or Li-SINR) values of L selected RSs (e.g., one to one mapping between a Li-RSRP (and / or Li-SINR) value and a selected RS) for the CC of the serving cell(s) and / or M Li- RSRP (and / or Li-SINR) values of M selected RSs (e.g., one to one mapping between a Li-RSRP (and / or Li-SINR) value and a selected RS) for the CC of the candidate cell(s). L and / or M can be configurable by the NW (e.g., can be indicated by the configuration parameters). Selected RSs can have RS quality (e.g., Li-RSRP (and / or Li-SINR) values) better than a configurable threshold indicated by the configuration parameters. For beam level quality comparison, a beam of CC in serving cell(s) can be a quasi co-location (QCL) RS or an RS quasi co-located (QCLed) with the QCL RS of an indicated TCI state for the corresponding CC. A beam of CC of candidate cell(s) can be any RS, of the CC in candidate cell(s), that meets the criteria of the corresponding event(s). Time To Trigger (TTT) can be used to reduce influences of ping-pong effects on the quality comparisons between different CCs of serving cell(s) and / or candidate cell(s). For example, an event (e.g., Event 1, Event 2, Event 3, Event 4, Event 5, Event 6, Event 7, or Event 8) can be triggered or fulfilled in response to the corresponding event criteria being satisfiedFW 6000755PCT02 -25-during the whole duration of the TTT. In an example, if a measurement gap is configured to the UE, the measurement(s) of RS(s) of candidate cell(s) can be performed by the UE within the measurement gap.

[0129] In an example, the configuration parameters can indicate a plurality of first CCs of a serving cell (or a serving cell group). The configuration parameters can indicate a plurality of second CCs of a candidate cell (or a candidate cell group). The configuration parameters can indicate a first value M (e.g., a positive integer) for the serving cell (or the serving cell group). The configuration parameters can indicate a second value N (e.g., a positive integer) for the candidate cell (or the candidate cell group). In an example, M can be equal to N. In this case, the configuration parameters can indicate only one positive integer value M (or N) for both the serving cell (or the serving cell group) and the candidate cell (or the candidate cell group). Based on the value M, the UE can select M CC(s) from the plurality of first CCs of the serving cell (or the serving cell group). The selected M CC(s) can have the best quality (e.g., best Li-RSRP (and / or Li-SINR) values) in the plurality of first CCs of the serving cell. Based on the value N, the UE can select N CC(s) from the plurality of second CCs of the candidate cell (or the candidate cell group). The selected N CC(s) can have the best quality (e.g., best Li-RSRP (and / or Li-SINR) values) in the plurality of second CCs of the candidate cell (or the candidate cell group). Then, the UE can perform event evaluation based on the M CC(s) of the serving cell (or the serving cell group) and N CC(s) of candidate cell (or the candidate cell group), such as in Event 1, Event 2, Event 3, Event 4, Event 5, Event 6, Event 7, and / or Event 8, where M=N=2 is used as an example in the previous description, other values of M and N are possible. In an example, the M CC(s) of the serving cell (or the serving cell group) and N CC(s) of candidate cell (or the candidate cell group) can only comprise one or more SCCs. In this case, the UE can perform event evaluation based on the M SCC(s) and / or PCC of the serving cell (or the serving cell group), as well as N SCC(s) and / or PCC of candidate cell (or the candidate cell group), such as in Event 1, Event 2, Event 3, Event 4, Event 5, Event 6, Event 7, and / or Event 8, where M=N=1 is used as an example in the previous description, other values of M and N are possible. In addition, it is straightforward to extend these examples for event evaluations to other cases. For example, M can be equal to or less than the number of the plurality of first CCs of serving cell (or the serving cell group). N can be equal to or less than the number of the plurality of second CCs of candidate cell (or the candidate cell group). In an example, an event can be defined as (or be trigger ed / fulfilled by): a quality of each CC of the N CCs of candidate cell (or candidate cell group) becomes an amount of an offset value better than that of at least one respective CC of M CCs of serving cell (or the serving cell group). In an example, anFW 6000755PCT02 -26-event can be defined as (or be triggered / fulfilled by): a quality of PCC of the N CCs of candidate cell (or candidate cell group) becomes an amount of an offset value better than that of PCC of M CCs of serving cell (or the serving cell group); and a quality of each CC of the N CCs of candidate cell (or candidate cell group) (except for PCC of the N CCs) becomes an amount of an offset value better than that of at least one respective CC of M CCs of serving cell (or serving cell group) (except for PCC of the M CCs). In these cases, M can be equal to N. In an example, the offset values of the comparisons between different CCs of candidate cell (or candidate cell group) and different CCs of serving cell (or serving cell group) can be different. For example, the comparisons of CCs in different frequency bands for serving cell (or serving cell group) and / or candidate cell (or candidate cell group) can use different offset values. In an example, the offset value of the comparison for different CCs of candidate cell (or candidate cell group) and / or different CCs of serving cell (or serving cell group) can be same (e.g., CCs are in same frequency band for serving cell (or serving cell group) and / or candidate cell (or candidate cell group)).

[0130] In an example, the UE can transmit the measurement report to the NW in response to an event being triggered based on event evaluation (e.g., Event 1, Event 2, Event 3, Event 4, Event 5, Event 6, Event 7, and / or Event 8). The measurement report can comprise an Li-RSRP (and / or Li-SINR) value for each RS of Q candidate cells (or candidate cell groups) and an identifier (e.g., SSBRI and / or CRI) of the corresponding RS. Each candidate cell (or candidate cell group) can comprise R CCs. Each CC of candidate cell (or candidate cell group) can comprise P RSs. In an example, different candidate cells (or candidate cell groups) can comprise different R values. Different CC of candidate cell (or candidate cell group) can comprise different P values. The configuration parameters can indicate the values (e.g., positive integer values) of P, Q, and R. Differential Li-RSRP (and / or Li-SINR) value and / or explicit Li-RSRP (and / or Li-SINR) value can be supported for the measurement report. The Li-RSRP (and / or Li- SINR) values (e.g., Differential Li-RSRP (and / or Li-SINR) value and / or explicit Lt- RSRP (and / or Li-SINR) value) for RS(s) and the corresponding identifier(s) (e.g., synchronization signal block resource indicator(s) (SSBRI(s)) and / or channel station information RS resource indicator(s) (CRI(s))) of the RS(s) of the same candidate cell (or candidate cell group) can be contiguously put together in the measurement report. The Li-RSRP (and / or Li-SINR) values (e.g., Differential Li-RSRP (and / or Li-SINR) value and / or explicit Li-RSRP (and / or Li-SINR) value) for RS(s) and the corresponding identifier(s) (e.g., SSBRI(s) and CRI(s)) of the RS(s) for different candidate cells (or candidate cell groups) can be put into the measurement report in order of index ofFW 6000755PCT02 -27-candidate cells (or candidate cell groups). FIG. 4 illustrates measurement report format when differential Li-RSRP (and / or Li-SINR) value is supported for the measurement report, in accordance with some implementations of the present disclosure. Multiple RSs and corresponding channel quality metrics of one or more candidate cell groups (e.g., candidate cell group o, ..., Q-i) can be included in the measurement report. As shown in FIG. 4, SSBRIs are used as an identifier of a corresponding RS, and Li-RSRP can be used as the channel quality metric. In some instances, a total number of P times R SSBRI entries for each candidate cell group can be included in the measurement report. P can be the number of component carriers, and R can be the number of beams reported per CC. The measurement report of FIG. 4 can use differential Li-RSRPs. For example, as shown in FIG. 4, for the candidate cell group o, explicit Li-RSRP value for SSBRI #1 is reported as a reference, and differential Li-RSRP values for other SSBRIs are reported as offsets or differences relative to that reference.

[0131] In an example, the UE can receive, via the serving cell, a medium access control control element (MAC CE) from the NW (e.g., source BS or gNB). The MAC CE can activate and / or deactivate one or more SCCs of the candidate cell (or candidate cell group). The one or more SCCs can be the N SCC(s) (e.g., Cl, C2 or both for Event 1, Event 2, Event 3, Event 4, Event 5, Event 6, and / or Event 7) of the candidate cell (or candidate cell group) used for event evaluation based on its measurements. FIG. 5 illustrates a structure of a MAC CE for activating or deactivating a cell, in accordance with some implementations of the present disclosure. The MAC CE can have the following format as illustrated in FIG. 5. The MAC CE can comprise a bit field indicating the CC index or identifier for which the corresponding SCC(s) is activated or deactivated. For example, if Ci is set to 1, it can indicate that the first SCC with CC index of Ci is activated. If Ci is set to o, it can indicate that the first SCC with CC index of Ci is deactivated. For other SCC indexes, same rule can be applied. The MAC CE can comprise a bit field indicating candidate cell (or candidate cell group) ID (or index) and / or serving cell (or serving cell group) ID (or index). The MAC CE can comprise a bit field indicating one or more tracking reference signal (TRS) IDs (e.g., TRS ID 1, ..., TRS ID N as shown in FIG. 5) for the indicated SCC(s) for activation of the corresponding candidate cell (or candidate cell group) or serving cell (or serving cell group). The MAC CE can comprise a bit field indicating one or more transmission configuration indicator (TCI) state IDs (e.g., TCI state 1, ..., TCI state M as shown in FIG. 5) for activation for the indicated SCC(s) for activation of the corresponding candidate cell (or candidate cell group) or serving cell (or serving cell group).FW 6000755PCT02 -28-

[0132] FIG. 6 illustrates a diagram of an example embodiment for a procedure 600 of mobility HO when multiple CCs are supported in serving cell (or serving cell group) and candidate cell(s) (or candidate cell group(s)), in accordance with some implementations of the present disclosure. As shown in the diagram, at 602, a UE can receive RRC message configurations indicating one or more of: a plurality of first RSs for a PCC and an SCC of a serving cell (or a serving cell group); a plurality of second RSs for a first CC and a second CC of a candidate cell (or a candidate cell group); L; M; a first RSRP threshold; a second RSRP threshold; a first offset value; and a second offset value. At 604, the UE can perform L1-RSRP measurements for each RS of the plurality of first RSs for the PCC and the SCC of the serving cell (or the serving cell group) and the plurality of second RSs for the first CC and the second CC of the candidate cell (or the candidate cell group). At 606, the UE can select: L RSs with Li-RSRP values being greater than the first RSRP threshold from the plurality of first RSs for PCC of the serving cell (or the serving cell group); and the M RSs with Li-RSRP values being greater than the second RSRP threshold from the plurality of second RSs for each CC of the candidate cell (or the candidate cell group). At 608, the UE can perform CC level measurement for PCC of the serving cell (or the serving cell group) and each CC of candidate cell (or the candidate cell group) based on linear power scale average of the selected L RSs for PCC of the serving cell (or the serving cell group) and the selected M RSs for each CC of the candidate cell (or the candidate cell group). At 610, the UE can evaluate the CC level RSRP value of first CC of candidate cell (or the candidate cell group). At 612, the UE can evaluate the CC level RSRP value of second CC of candidate cell (or the candidate cell group). If the CC level RSRP value of first CC of candidate cell (or the candidate cell group) becomes an amount of the first offset value better than that of PCC of serving cell (or the serving cell group) and the CC level RSRP value of second CC of candidate cell (or the candidate cell group) becomes an amount of the second offset value better than that of PCC of serving cell (or the serving cell group), the event can be fulfilled. In some embodiments, in response to the event being fulfilled, at 614, the UE can transmit a measurement report comprising Li-RSRP values of M RSs for the first CC and the second CC of the candidate cell (or the candidate cell group) and / or identifiers of the corresponding M RSs of the first CC and the second CC of the candidate cell (or the candidate cell group). At 616, the UE can perform a cell switching to the candidate cell (or the candidate cell group) with the first CC and the second CC in response to receiving a cell switch command from the NW.

[0133] FIG. 7 illustrates a diagram of an example embodiment for a procedure 700 of mobility HO when multiple CCs are supported in the serving cell (or serving cell group)FW 6000755PCT02 -29-and candidate cell(s) (or candidate cell group(s)), in accordance with some implementations of the present disclosure. As shown in the diagram, at 702, a UE can receive RRC message configurations indicating one or more of: a plurality of first RSs for a first CC and a second CC of a candidate cell (or candidate cell group); a PCC and SCC of a serving cell (or a serving cell group); a first offset value; and a second offset value. At 704, the UE can perform Li-RSRP measurements for each RS of the plurality of first RSs for the first CC and the second CC of the candidate cell (or the candidate cell group). At 706, the UE can evaluate an Li-RSRP value of an RS of the first CC of candidate cell (or the candidate cell group). At 708, the UE can evaluate an Li-RSRP value of an RS of the second CC of candidate cell (or the candidate cell group). If an Li-RSRP value of an RS of the first CC of candidate cell (or the candidate cell group) becomes an amount of the first offset value better than that of QCL RS of an indicated TCI state for PCC of serving cell (or serving cell group) and an Li-RSRP value of an RS of the second CC of candidate cell (or the candidate cell group) becomes an amount of the second offset value better than that of QCL RS of the indicated TCI state for PCC of serving cell (or serving cell group), the event can be fulfilled. In another example, if an Li-RSRP value of an RS of the first CC of candidate cell (or the candidate cell group) becomes an amount of the first offset value better than that of a first RS QCLed with QCL RS of an indicated TCI state for PCC of serving cell (or serving cell group) and an Li-RSRP value of an RS of the second CC of candidate cell (or the candidate cell group) becomes an amount of the second offset value better than that of the first RS QCLed with QCL RS of the indicated TCI state for PCC of serving cell (or serving cell group), the event can be fulfilled. In some embodiments, at 710, in response to the event being fulfilled, the UE can transmit a beam measurement report comprising Li-RSRP values of RSs for the first CC and the second CC of the candidate cell (or the candidate cell group) and an identifier of the corresponding RS of the first CC and the second CC of the candidate cell (or the candidate cell group). At 712, the UE can perform a cell switching to the candidate cell with the first CC and the second CC in response to receiving a cell switch command from the NW.

[0134] FIG. 8 illustrates a method 800, in accordance with some implementations of the present disclosure. The method 800 illustrates a diagram of an example mobility HO procedure when multiple CCs are supported in a serving cell group and a candidate cell group. The method 800 can be performed by a communication network that includes a UE 802, a serving cell group 804, and a candidate cell group 806. In some instances, the UE 802 can be an example of the UE of FIG. 3, the serving cell group 804 can be an example of the serving cell group of FIG. 3, and the candidate cell group 806 can be an example of the candidate cell group o of FIG. 3.FW 6000755PCT02 -30-

[0135] At 808, the serving cell group 804 can transmit a configuration to the UE 802. Accordingly, the UE 802 can receive the configuration from the serving cell group 804 at 808. For example, the configuration can be transmitted to the UE 802 through a serving base station that controls one or more serving cells of the serving cell group 804. In some embodiments, the configuration can indicate a first component carrier (CC) (e.g., PCC_Si of FIG. 3) of the serving cell group 804, a second CC (e.g., SCC_S2 of FIG. 3) of the serving cell group 804, a first CC (e.g., CC_Ci of FIG. 3) of the candidate cell group 806, a second CC (e.g., CC_C2 of FIG. 3) of the candidate cell group 806. The configuration can further indicate a condition for triggering an event (e.g., Event 1, Event 2, Event 3, Event 4, Event 5, Event 6, Event 7, or Event 8 as described above). In some embodiments, the condition can be represented as one or more bits within the configuration. For example, the one or more bits can be a parameter, an information element, or a field in the configuration. The one or more bits can indicate or encode a predefined triggering criterion or principal, one or more threshold values related to the triggering criterion or principal, or a combination thereof. The UE 802 can receive the one or more bits and determine the condition based on the received one or more bits. The condition can be based on at least one of a channel quality metric of the first CC of the serving cell group, a channel quality metric of the second CC of the serving cell group, a channel quality metric of the first CC of the candidate cell group, or a channel quality metric of the second CC of the candidate cell group.

[0136] In some embodiments, at 808, the UE 802 can receive one or more radio resource control (RRC) messages from the serving cell group 804. Each of the one or more RRC messages comprises at least a portion of the configuration. In some embodiments, the serving cell group 804 can include one or more serving cells. For one example, as shown in FIG. 3, the serving cell group 804 can include serving cells on PCC_Si and SCC_S2 respectively. For another example, the serving cell group 804 can include one single cell with multiple CCs. The candidate cell group 806 can include one or more candidate cells. For one example, as shown in FIG. 3, the candidate cell group 806 can include candidate cells on CC_Ci and CC_C2 respectively. For another example, the candidate cell group 806 can include one single cell with multiple CCs.

[0137] The configuration can further indicate a first plurality of reference signals (RSs) (e.g., SSB or CSI-RS) associated with the first CC of the serving cell group 804 and the second CC of the serving cell group 804, and a second plurality of RSs (e.g., SSB or CSI-RS) associated with the first CC of the candidate cell group 806 and the second CC of the candidate cell group 806. At 810, the serving cell group 804 can transmit the first plurality of RSs to the UE 802. Accordingly, the UE 802 can receive the first plurality ofFW 6000755PCT02 -31-RSs from the serving cell group 804 at 810. At 812, the candidate cell group 806 can transmit the second plurality of RSs to the UE 802. Accordingly, the UE 802 can receive the second plurality of RSs from the candidate cell group 806 at 812.

[0138] At 814, the UE 802 can perform measurement. In some embodiments, performing measurement includes the UE 802 determining a channel quality metric of the first CC of the serving cell group 804 and a channel quality metric of the second CC of the serving cell group 804 based on measurements of the first plurality of RSs. Performing measurement can also include determining a channel quality metric of the first CC of the candidate cell group 806 and a channel quality metric of the second CC of the candidate cell group 806 based on measurements of the second plurality of RSs. The channel quality metric can be a beam level channel quality metric (e.g., Li-RSRP or Li- SINR of an RS, QCL RS, or QCLed) or a CC level channel quality metric (e.g., a linear power scale average value of Li-RSRP or Li-SINR for one or more selected RSs). In some embodiments, the UE 802 can select one or more RSs associated with the first CC of the serving cell group 804, the second CC of the serving cell group 804, the first CC of the candidate cell group 806, or the second CC of the candidate cell group 806. For example, as described with respect to 606 of FIG. 6, the UE 802 can select one or more RSs from the first plurality of RSs and the second plurality of RSs based on a threshold. The threshold can be indicated by the configuration.

[0139] In some embodiments, performing measurement includes evaluating whether the event occurs based on the at least one of the channel quality metric of the first CC of the serving cell group, the channel quality metric of the second CC of the serving cell group, the channel quality metric of the first CC of the candidate cell group, or the channel quality metric of the second CC of the candidate cell group. In some other embodiments, evaluation and measurement can be considered as separate operations.

[0140] In some embodiments, the UE 802 can determine that the event occurs in response to detecting that the condition for triggering the event is satisfied. In some embodiments, for example, as described with respect to Event 1, the condition includes the following: the channel quality metric of the first CC of the candidate cell group 806 is larger than the channel quality metric of the first CC of the serving cell group 804 by a first offset; and the channel quality metric of the second CC of the candidate cell group 806 is larger than the channel quality metric of the first CC of the serving cell group 804 by a second offset. The first offset can be the same as or different from the second offset. In some cases, the first offset and / or the second offset can be zero.FW 6000755PCT02 -32-

[0141] In some embodiments, for example, as described with respect to Event 2, the condition includes the following: a larger one of the channel quality metric of the first CC of the candidate cell group 806 and the channel quality metric of the second CC of the candidate cell group 806 is larger than the channel quality metric of the first CC of the serving cell group 804 by a first offset; and a difference between the channel quality metric of the first CC of the candidate cell group 806 and the channel quality metric of the second CC of the candidate cell group 806 is equal to or smaller than a second offset. The first offset can be the same as or different from the second offset. In some cases, the first offset and / or the second offset can be zero.

[0142] In some embodiments, for example, as described with respect to Event 3, the condition includes the following: the channel quality metric of the first CC of the candidate cell group 806 is larger than a larger one of the channel quality metric of the first CC of the serving cell group 804 and the channel quality metric of the second CC of the serving cell group 804 by a first offset; and the channel quality metric of the second CC of the candidate cell group 806 is larger than the larger one of the channel quality metric of the first CC of the serving cell group 804 and the channel quality metric of the second CC of the serving cell group 804 by a second offset. The first offset can be the same as or different from the second offset. In some cases, the first offset and / or the second offset can be zero.

[0143] In some embodiments, for example, as described with respect to Event 4, the condition includes the following: the channel quality metric of the first CC of the candidate cell group 806 is larger than a first threshold; and the channel quality metric of the second CC of the candidate cell group 806 is larger than a second threshold. The first threshold can be the same as or different from the second threshold.

[0144] In some embodiments, for example, as described with respect to Event 5, the condition includes the following: a larger one of the channel quality metric of the first CC of the candidate cell group 806 and the channel quality metric of the second CC of the candidate cell group 806 is larger than a threshold; and a difference between the channel quality metric of the first CC of the candidate cell group 806 and the channel quality metric of the second CC of the candidate cell group 806 is equal to or smaller than a offset. In some cases, the offset can be zero.

[0145] In some embodiments, for example, as described with respect to Event 6, the condition includes the following: the channel quality metric of the first CC of the serving cell group 804 is smaller than a first threshold; the channel quality metric of the second CC of the serving cell group 804 is smaller than a second threshold; the channel qualityFW 6000755PCT02 -33-metric of the first CC of the candidate cell group 806 is larger than a third threshold; and the channel quality metric of the second CC of the candidate cell group 806 is larger than a fourth threshold.

[0146] In some embodiments, for example, as described with respect to Event 7, the condition includes the following: a larger one of the channel quality metric of the first CC of the serving cell group 804 and the channel quality metric of the second CC of the serving cell group 804 is smaller than a first threshold; and a larger one of the channel quality metric of the first CC of the candidate cell group 806 and the channel quality metric of the second CC of the candidate cell group 806 is larger than a second threshold.

[0147] In some embodiments, for example, as described with respect to Event 8, the condition includes the following: a larger one of the channel quality metric of the first CC of the serving cell group 804 and the channel quality metric of the second CC of the serving cell group 804 is smaller than a threshold.

[0148] In some embodiments, the configuration further indicates a time to trigger (TTT) period. The UE 802 can determine that the event occurs in response to detecting that the condition for triggering the event is satisfied during the TTT period.

[0149] At 816, the UE 802 can transmit a measurement report to the serving cell group 804 in response to an occurrence of the event based on the condition. This step can be similar to or the same as operations described with respect to 614 of FIG. 6 or 710 of FIG. 7. In some embodiments, the measurement report indicates one or more RS received power (RSRP) values and one or more identifiers (e.g., SSB RI or CRI) for one or more RSs in the first plurality of RSs and the second plurality of RSs. In some embodiments, as shown in FIG. 4, the measurement report can include measurements of the RSs transmitted from or associated with multiple CCs of one or more candidate cells of the candidate cell group 806. The UE 802 can transmit the measurement report via a physical uplink shared channel (PUSCH) or a physical uplink control channel (PUCCH).

[0150] At 822, the serving cell group 804 can transmit a cell switching command to the UE 802. Accordingly, the UE 802 can receive the cell switching command from the serving cell group 804 at 822. In some embodiments, the serving cell group 804 transmits the cell switching command to the UE 802 in response to receiving the measurement report from the UE 802. For instance, based on the measurement report, the serving cell group 804 can determine to switch a serving cell of the UE 802 to one or more cells in the candidate cell group 806, and thus transmit the cell switching command to the UE 802.FW 6000755PCT02 -34-

[0151] At 824, the UE 802 can perform a cell switching from the serving cell group 804 to the candidate cell group 806 in response to receiving the cell switching command. This step can be similar to or the same as operations described with respect to 616 of FIG. 6 or 712 of FIG. 7.

[0152] In some cases, the multiple CCs of a candidate cell (or a candidate cell group) can be associated with different timing advance groups (TAGs). For example, the multiple CCs of candidate cell (or candidate cell group) can be allocated with (or configured with) different transmission reception points (TRPs) in the same candidate cell (or candidate cell group). When the UE performs early random access (RA) for the multiple CCs associated with different TAGs of the same candidate cell (or candidate cell group), multiple physical downlink control channel (PDCCH) orders may be needed and transmitted to trigger a respective RA for each TAG of the candidate cell (or candidate cell group) based on the existing technologies, which could result in high signaling overhead in physical layer. In addition, if the UE is configured with multiple candidate cells (or candidate cell groups), the signaling overhead of multiple PDCCH orders can be further higher since UE may need to perform multiple early RAs for each candidate cell (or candidate cell group) of the configured multiple candidate cells (or candidate cell groups). Therefore, the PDCCH order needs to be further enhanced to trigger multiple RAs for different TAGs of the candidate cell (or candidate cell group) by an indication of an PDCCH order, and meanwhile, the signaling overhead of PDCCH orders in physical layer can be significantly reduced. FIG. 9 illustrates a diagram of an example embodiment for a procedure of RA when multiple TAGs are supported in candidate cells (or candidate cell groups), in accordance with some implementations of the present disclosure. A candidate cell (or candidate cell group) can be configured with multiple TAGs. The multiple CCs of the candidate cell (or the candidate cell group) can be associated with (or belong to) different TAGs. For example, as shown in FIG. 9, in candidate cell (or cell group) o, CCi and CC2 can be associated with a first (1st) TAG. CC3 and CC4 of the candidate cell (or cell group) o can be associated with a second (2nd) TAG. Similarly, for candidate cell (or cell group) 1, the multiple CCs of the candidate cell (or the candidate cell group) can be associated with different TAGs (e.g., 1stTAG, and 2ndTAG). The configuration parameters can indicate a plurality of TAGs (e.g., 1stTAG, and 2ndTAG) for a candidate cell (or a candidate cell group). The UE can perform early RA(s) (e.g., random access before cell switching from the serving cell to the candidate cell) to the candidate cell (or the candidate cell group) for different TAGs based on an indication of a PDCCH order.FW 6000755PCT02 -35-

[0153] FIG. 10 illustrates a format of an example embodiment for a PDCCH order to trigger random access for multiple TAGs in candidate cell(s), in accordance with some implementations of the present disclosure. The PDCCH order can comprise multiple bit fields. As shown in FIG. to, a first bit field of the PDCCH order can indicate a randomaccess preamble index for both TAGs of the candidate cell (or the candidate cell group). For the 1stTAG of candidate cell or candidate cell group (or serving cell / serving cell group), the PDCCII order can comprise multiple bit fields indicating one or more of: first UL / SUL indicator, first SS / PBCH index, first physical random access channel (PRACH) Mask index, and first PRACH retransmission indicator. For the 2ndTAG of candidate cell (or candidate cell group) (or serving cell / serving cell group), the PDCCH order can comprise multiple bit fields indicating one or more of: second UL / SUL indicator, second SS / PBCH index, second PRACH Mask index, and second PRACH retransmission indicator. In an example, the PDCCH order can comprise a bit field indicating a TAG ID.

[0154] FIG. 11 illustrates a diagram of an example embodiment for a procedure 1100 of RA when multiple CCs with multiple TAGs are supported in candidate cell(s), in accordance with some implementations of the present disclosure. In this case, the UE can perform autonomous random access to candidate cell(s) based on measurements of candidate cell(s) and / or serving cell(s). As shown in FIG. 11, at 1102, the UE can receive RRC messages comprising configuration parameters indicating one or more of: RA resources; conditional parameters for RA for a PCC (or a first CC) and one or more SCCs (or second CCs) for candidate cell(s); and / or a maximum number for RA. At 1104, the UE can perform condition evaluations based on measurements of Li-RSRP values for the PCC and the one or more SCCs of candidate cell(s) (or candidate cell group(s)) and / or serving cell (or serving cell group). At 1106, the UE can determine whether the condition is fulfilled for PCC and / or one or more SCCs of candidate cell(s) (or candidate cell group(s)) and / or serving cell (or serving cell group). If the condition is fulfilled for PCC and / or one or more SCCs of candidate cell(s) (or candidate cell group(s)) and / or serving cell (or serving cell group), for example, Li-RSRP of serving cell (or serving cell group) (e.g., PCC of serving cell (or serving cell group)) being less than a first threshold and Li- RSRP of a candidate cell (or a candidate cell group) (e.g., Li-RSRP value of a PCC / SCC of a TAG of candidate cell (or candidate cell group)) being greater than a second threshold, at 1108, the UE can transmit preamble to one or more CCs of a TAG of candidate cell(s) (or candidate cell group(s)). The configuration parameters can indicate the first threshold and the second threshold. At 1110, the UE can verify whether a response / confirmation is received. If the response / confirmation is received from serving (or candidate) cell for the transmission of preamble within a time window andFW 6000755PCT02 -36-transmission times is less than the maximum number, at 1112, the UE can stop (re)transmission of the preamble and keep the TA value for the corresponding TAG for the candidate cell(s) (or candidate cell group(s)). The configuration parameters can indicate the time window, or a timer associated with the time window.

[0155] In some embodiments, the response / confirmation received from serving (or candidate) cell for the transmission of preamble (e.g., within the time window) can be a MAC CE, an RAR, or a group common PDCCH scrambled with a dedicated RNTI for the confirmation of random access for the corresponding TAGs of the candidate cell(s) (or candidate cell group(s)). The response / confirmation can indicate the transmitted random access preamble index. The response / confirmation can indicate the corresponding TAG ID of candidate cell (or candidate cell group) for which the random access is performed by UE. The response / confirmation can indicate the TA value for the corresponding TAG ID of candidate cell (or candidate cell group). In an example, the response / confirmation can indicate multiple TA values for the multiple TAG IDs of candidate cell (or candidate cell group) and a respective TA value for each of the multiple TAG IDs is indicated.

[0156] FIG. 12 illustrates a diagram of an example embodiment for a cell switching command (CSC) 1200 when multiple CCs with multiple TAGs are supported in candidate cell(s), in accordance with some implementations of the present disclosure. As shown in FIG. 12, the CSC 1200 can comprise a plurality of bit fields. A bit field 1201 of the CSC can indicate Target Config ID, which can be used by the UE to identify the index of candidate target configuration to apply for cell switch. A bit field 1202a of the CSC can indicate S / U for 1stTAG of candidate cell (or candidate cell group), which can be used by UE to identify which UL carrier to transmit the PRACH of the contention-free Random Access Resources for 1st TAG. A bit field 1203a of the CSC can indicate Timing Advance Command for 1stTAG of candidate cell (or candidate cell group), which can be used by UE to identify whether the TA is valid for 1st TAG of the target or candidate cell (or candidate cell group). A bit field 1204a of the CSC can indicate TCI state ID for 1stTAG of candidate cell (or candidate cell group), which can be used by UE to activate the TCI state for 1stTAG of the target or candidate cell (or candidate cell group). A bit field 1205a of the CSC can indicate a Random Access Preamble index for 1stTAG of candidate cell (or candidate cell group), which can be used by UE to identify the Random Access Preamble index for 1st TAG of the target or candidate cell (or candidate cell group). A bit field 1206a of the CSC can indicate a SS / PBCH index for istTAG of candidate cell (or candidate cell group), which can be used by UE to identify the SS / PBCH that can be used to determine the RACH occasion for the PRACH transmission of the contention-freeFW 6000755PCT02 -37-Random Access Resources for 1st TAG of the target or candidate cell (or candidate cell group). A bit field 1207a of the CSC can indicate a PRACH Mask index for 1stTAG of candidate cell (or candidate cell group), which can be used by UE to identify the RACH occasion(s) associated with the SS / PBCH indicated by "SS / PBCH index" for the PRACH transmission of the contention-free Random Access Resources for 1st TAG of candidate cell (or candidate cell group).

[0157] Similarly, a bit field 1202b of the CSC can indicate S / U for 2ndTAG of candidate cell (or candidate cell group), which can be used by UE to identify which UL carrier to transmit the PRACH of the contention-free Random Access Resources for 2ndTAG. A bit field 1203b of the CSC can indicate Timing Advance Command for 2ndTAG of candidate cell (or candidate cell group), which can be used by UE to identify whether the TA is valid for 2ndTAG of the target or candidate cell (or candidate cell group). A bit field 1204b of the CSC can indicate TCI state ID for 2ndTAG of candidate cell (or candidate cell group), which can be used by UE to activate the TCI state for 2ndTAG of the target or candidate cell (or candidate cell group). A bit field 1205b of the CSC can indicate a Random Access Preamble index for 2ndTAG of candidate cell (or candidate cell group), which can be used by UE to identify the Random Access Preamble index for 2ndTAG of the target or candidate cell (or candidate cell group). A bit field 1206b of the CSC can indicate a SS / PBCH index for 2ndTAG of candidate cell (or candidate cell group), which can be used by UE to identify the SS / PBCH that can be used to determine the RACH occasion for the PRACH transmission of the contention-free Random Access Resources for 2ndTAG of the target or candidate cell (or candidate cell group). A bit field 1207b of the CSC can indicate a PRACH Mask index for 2ndTAG of candidate cell (or candidate cell group), which can be used by UE to identify the RACH occasion(s) associated with the SS / PBCH indicated by "SS / PBCH index" for the PRACH transmission of the contention-free Random Access Resources for 2ndTAG of candidate cell (or candidate cell group). In an example, a bit field of the CSC can indicate a TAG ID.

[0158] FIG. 13 illustrates a method 1300, in accordance with some implementations of the present disclosure. The method 1300 illustrates a diagram of an example mobility HO procedure when multiple CCs are supported in a serving cell group and a candidate cell group. The method 1300 can be performed by a communication network that includes a UE 1302, a serving cell group 1304, and a candidate cell group 1306. In some instances, the UE 1302 can be an example of the UE of FIG. 9, the serving cell group 1304 can be an example of the serving cell group of FIG. 9, and the candidate cell group 1306 can be an example of the candidate cell group o or candidate cell group 1 of FIG. 9.FW 6000755PCT02 -38-

[0159] At 1308, the serving cell group 1304 can transmit a configuration to the UE 1302. Accordingly, the UE 1302 can receive the configuration from the serving cell group 1304 at 1308. For example, the configuration can be transmitted to the UE 1302 through a serving base station that controls one or more serving cells of the serving cell group 1304. In some embodiments, the configuration can indicate at least a first timing advance group (TAG) of the candidate cell group 1306 and a plurality of component carriers (CCs) of the candidate cell group 1306, and the plurality of CCs comprises at least a first CC associated with the first TAG.

[0160] In some embodiments, at 1308, the UE 1302 can receive one or more radio resource control (RRC) messages from the serving cell group 1304. Each of the one or more RRC messages comprises at least a portion of the configuration. In some embodiments, the serving cell group 1304 can include one or more serving cells. The candidate cell group 1306 can include one or more candidate cells.

[0161] In some embodiments, the UE 1302 can perform autonomous random access to candidate cell(s) based on measurements of candidate cell(s) and / or serving cell(s). For example, at 1310, the UE 1302 can perform measurements on the plurality of CCs. In some cases, the UE 1302 can select one or more CCs (e.g., the first CC) from the plurality of CCs based on results of the measurements and a condition for triggering a random access. The condition is satisfied on the selected CC(s). The condition for triggering the random access can be indicated by the configuration or included in the configuration. The condition can include: a first channel quality metric of one of the plurality of CCs of the candidate cell group is equal to or larger than a first threshold, and a second channel quality metric of a CC of the serving cell group is smaller than a second threshold. The first threshold and the second threshold can be included in the configuration. In some cases, each of the first channel quality metric and the second channel quality metric can be a reference signal received power (RSRP). In some cases, each of the first channel quality metric and the second channel quality metric can be a signal -to-interference- plus-noise ratio (SINR).

[0162] In some embodiments, at 1312, the UE 1302 can transmit a random access preamble to the candidate cell group 1306 for the first TAG. For example, the UE 1302 can transmit a random access preamble to the candidate cell group 1306 for the first TAG in response to selecting the first CC.

[0163] In some embodiments, the UE 1302’s random access to candidate cell(s) can be triggered by the network side. For example, the serving cell group 1304 can transmit an indication (not shown in FIG. 13) to the UE 1302. Accordingly, the UE 1302 canFW 6000755PCT02 -39-receive the indication from the serving cell group 1304. In some instances, the plurality of CCs further includes a second CC associated with a second TAG of the candidate cell group 1306. The indication can indicate a request for a first random access for the first TAG and a second random access for the second TAG. The indication can further indicate the random access preamble, a first random access resource for the first random access, and a second random access resource for the second random access. In some embodiments, the indication includes at least one of a physical downlink control channel (PDCCH) order, downlink control information (DCI), or a medium access control (MAC)-control element (CE).

[0164] In some embodiments, at 1312, the UE 1302 can transmit the random access preamble to the candidate cell group 1306 for the first TAG via the first random access resource. In addition, at 1312, the UE 1302 can also transmit the random access preamble to the candidate cell group 1306 for the second TAG via the second random access resource. The UE 1302 can transmit the random access preamble to the candidate cell group 1306 for the first TAG and for the second TAG in response to receiving the indication from the serving cell group 1304. The first random access resource can include one or more of: a first uplink supplementary carrier indicator, a first synchronization signal block (SS / PBCH) index, a first physical random access channel (PRACH) mask index, or a first PRACH retransmission indicator. The second random access resource can include one or more of: a second UL / SUL indicator, a second SS / PBCH index, a second PRACH mask index, or a second PRACH retransmission indicator.

[0165] In some embodiments, such a network triggered early random access procedure can be combined with the method 800 of FIG. 8. For example, the multiple CCs of the candidate cell group 806 can support different TAGs (e.g., a first TAG and a second TAG). As shown in FIG. 8, at 818, the serving cell group 804 can transmit an indication to the UE 802. Accordingly, the UE 802 can receive the indication from the serving cell group 804 at 818. The indication can indicate a request for a first random access for the first TAG and a second random access for the second TAG. The indication can further indicate a random access preamble, a first random access resource for the first random access, and a second random access resource for the second random access. At 820, the UE 804 can transmit the random access preamble to the candidate cell group 806 in response to receiving the indication. Accordingly, the candidate cell group 806 can receive the random access preamble from the UE 804 at 820. In some cases, at 820, the UE 802 can transmit the random access preamble to the candidate cell group 806 for the first TAG via the first random access resource, and transmit the random accessFW 6000755PCT02 -40-preamble to the candidate cell group 806 for the second TAG via the second random access resource.

[0166] Returning back to FIG. 13, at 1314, the candidate cell group 1306 can transmit a response to the UE 1302. Accordingly, the UE 1302 can receive the response from the candidate cell group 1306 at 1314. The response can confirm reception of the random access preamble at the candidate cell group 1306. The UE 1302 can receive one of the following that includes the response: a medium access control (MAC)-control element (CE), a group common PDCCH, or a random access response (RAR) command.

[0167] In some cases, the response indicates at least one of: an index of the random access preamble; an identifier (ID) of the first TAG; or a first time advance (TA) value for the first TAG.

[0168] In some cases, the plurality of CCs further include a second CC associated with a second TAG of the candidate cell group. The response indicates a first time advance (TA) value for the first TAG and a second TA value for the second TAG.

[0169] In some embodiments, at 1316, the serving cell group 1304 can transmit a cell switching command to the UE 1302. Accordingly, the UE 1302 can receive the cell switching command from the serving cell group 1304 at 1316. The cell switching command can indicate supplementary uplink carrier or uplink carrier for the first TAG, supplementary uplink carrier or uplink carrier for the second TAG, a first timing advance command for the first TAG, a second timing advance command for the second TAG, a first transmission configuration indicator (TCI) state ID for the first TAG, and a second TCI state ID for the second TAG (e.g., as shown in FIG. 12). At 1318, the UE 1302 can perform a cell switching from the serving cell group 1304 to the candidate cell group 1306 in response to receiving the cell switching command.

[0170] It is understood that steps or operations shown in the methods, the signaling exchange diagrams, or the flow diagrams described in this disclosure (e.g., as described with respect to FIGS. 2, 6-8, 11, and 13) are not exhaustive and that other operations can be performed as well before, after, or between any of the illustrated operations. Further, some of the steps or operations can be omitted, performed simultaneously, or in a different order than shown in those figures.

[0171] The network entity described in this disclosure can include a base station, a network relay node, or a plurality of base stations each configured to perform at least one of the network entity operations described above. For example, a first base station of the network entity can transmit the one or more RRC messages. A second base station of the network entity can receive the measurement report. The first base station or the secondFW 6000755PCT02 -41-base station (or a third base station of the network entity) can transmit the cell switching command. In another example, a first base station of the network entity can transmit the one or more RRC messages. A second base station of the network entity can transmit the PDCCH order. The first base station or the second base station (or a third base station of the network entity) can receive the random access preamble. The network entity operations can be distributed among different base stations in any combination or configuration, without limitation to the specific examples provided herein.

[0172] FIG. 14 illustrates an example communications system 1400 in which some embodiments can be implemented, in accordance with some implementations of the present disclosure. The CSC can comprise a plurality of bit fields. Communications system 1400 includes an access node 1410 serving user equipments (UEs) with coverage 1401, such as UEs 1420. In a first operating mode, communications to and from a UE pass through access node 1410 with a coverage area 1401. The access node 1410 is connected to a backhaul network 1415 for connecting to the internet, operations and management, and so forth. In a second operating mode, communications to and from a UE do not pass through access node 1410, however, access node 1410 typically allocates resources used by the UE to communicate when specific conditions are met. Communications between a pair of UEs 1420 can use a sidelink connection (shown as two separate one-way connections 1425). In FIG. 14, the sidelink communication is occurring between two UEs operating inside of coverage area 1401. However, sidelink communications, in general, can occur when UEs 1420 are both outside coverage area 1401, both inside coverage area 1401, or one inside and the other outside coverage area 1401. Communication between a UE and access node pair occur over uni-directional communication links, where the communication links between the UE and the access node are referred to as uplinks 1430, and the communication links between the access node and UE is referred to as downlinks 1435.

[0173] Access nodes can also be commonly referred to as Node Bs, evolved Node Bs (eNBs), next generation (NG) Node Bs (gNBs), master eNBs (MeNBs), secondary eNBs (SeNBs), master gNBs (MgNBs), secondary gNBs (SgNBs), network controllers, control nodes, base stations, access points, transmission points (TPs), transmission-reception points (TRPs), cells, carriers, macro cells, femtocells, pico cells, and so on, while UEs can also be commonly referred to as mobile stations, mobiles, terminals, users, subscribers, stations, and the like. Access nodes can provide wireless access in accordance with one or more wireless communication protocols, e.g., the Third Generation Partnership Project (3GPP) long term evolution (LTE), LTE advanced (LTE-A), 5G, 5G LTE, 5G NR, sixth generation (6G), High Speed Packet Access (HSPA), the IEEE 802.11 family of standards,FW 6000755PCT02 -42-such as 802.na / b / g / n / ac / ad / ax / ay / be, etc. While it is understood that communications systems can employ multiple access nodes capable of communicating with a number of UEs, only one access node and two UEs are illustrated for simplicity.

[0174] FIG. 15 illustrates an example communication system 1500 in which some embodiments discussed herein can be implemented, in accordance with some implementations of the present disclosure. In general, the system 1500 enables multiple wireless or wired users to transmit and receive data and other content. The system 1500 can implement one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), or non- orthogonal multiple access (NOMA).

[0175] In this example, the communication system 1500 includes electronic devices (ED) I5ioa-i5ioc, radio access networks (RANs) i.52oa-i52ob, a core network 1530, a public switched telephone network (PSTN) 1540, the Internet 1550, and other networks 1560. While certain numbers of these components or elements are shown in FIG. 15, any number of these components or elements can be included in the system 1500.

[0176] The EDs 15103-15100 are configured to operate or communicate in the system 1500. For example, the EDs 15103-15100 are configured to transmit or receive via wireless or wired communication channels. Each ED 15103-15100 represents any suitable end user device and can include such devices (or can be referred to) as a user equipment or device (UE), wireless transmit or receive unit (WTRU), mobile station, fixed or mobile subscriber unit, cellular telephone, personal digital assistant (PDA), smartphone, laptop, computer, touchpad, wireless sensor, or consumer electronics device.

[0177] The RANs I52oa-i52ob here include base stations I57oa-i57ob, respectively. Each base station I57oa-i57ob is configured to wirelessly interface with one or more of the EDs 15103-15100 to enable access to the core network 1530, the PSTN 1540, the Internet 1550, or the other networks 1560. For example, the base stations I57oa-i57ob can include (or be) one or more of several well-known devices, such as a base transceiver station (BTS), a Node-B (NodeB), an evolved NodeB (eNB), a Next Generation (NG) NodeB (gNB), a gNB centralized unit (gNB-CU), a gNB distributed unit (gNB-DU), a Home NodeB, a Home eNodeB, a site controller, an access point (AP), or a wireless router. The EDs 15103-15100 are configured to interface and communicate with the Internet 1550 and can access the core network 1530, the PSTN 1540, or the other networks 1560.FW 6000755PCT02 -43-

[0178] In the embodiment shown in FIG. 15, the base station 1570a forms part of the RAN 1520a, which can include other base stations, elements, or devices. Also, the base station 1570b forms part of the RAN 1520b, which can include other base stations, elements, or devices. Each base station I57oa-i57ob operates to transmit or receive wireless signals within a particular geographic region or area, sometimes referred to as a “cell.” In some embodiments, multiple-input multiple-output (MIMO) technology can be employed having multiple transceivers for each cell.

[0179] The base stations I57oa-i57ob communicate with one or more of the EDs 15103-15100 over one or more air interfaces 1590 using wireless communication links. The air interfaces 1590 can utilize any suitable radio access technology.

[0180] It is contemplated that the system 1500 can use multiple channel access functionality, including such schemes as described above. In particular embodiments, the base stations and EDs implement 5G New Radio (NR), LTE, LTE-A, or LTE-B. Of course, other multiple access schemes and wireless protocols can be utilized.

[0181] The RANs 15203-1520!) are in communication with the core network 1530 to provide the EDs 15103-15100 with voice, data, application, Voice over Internet Protocol (VoIP), or other services. Understandably, the RANs 15203-1520!) or the core network 1530 can be in direct or indirect communication with one or more other RANs (not shown). The core network 1530 can also serve as a gateway access for other networks (such as the PSTN 1540, the Internet 1550, and the other networks 1560). In addition, some or all of the EDs 15103-15100 can include functionality for communicating with different wireless networks over different wireless links using different wireless technologies or protocols. Instead of wireless communication (or in addition thereto), the EDs can communicate via wired communication channels to a service provider or switch (not shown), and to the Internet 1550.

[0182] Although FIG. 15 illustrates one example of a communication system, various changes can be made to FIG. 15. For example, the communication system 1500 could include any number of EDs, base stations, networks, or other components in any suitable configuration.

[0183] FIGS. 16A and 16B illustrate example devices that can implement some embodiments discussed herein, in accordance with some implementations of the present disclosure. In particular, FIG. 16A illustrates an example ED 1610, and FIG. 16B illustrates an example base station 1670. These components could be used in the system 1600 or in any other suitable system.FW 6000755PCT02 -44-

[0184] As shown in FIG. 16A, the ED 1610 includes at least one processing unit 1600. The processing unit 1600 implements various processing operations of the ED 1610. For example, the processing unit 1600 could perform signal coding, data processing, power control, input / output processing, or any other functionality enabling the ED 1610 to operate in the system 1600. The processing unit 1600 also supports the methods and teachings described in more detail above. Each processing unit 1600 includes any suitable processing or computing device configured to perform one or more operations. Each processing unit 1600 could, for example, include a microprocessor, microcontroller, digital signal processor, field programmable gate array, or application specific integrated circuit.

[0185] The ED 1610 also includes at least one transceiver 1602. The transceiver 1602 is configured to modulate data or other content for transmission by at least one antenna or NIC (Network Interface Controller) 1604. The transceiver 1602 is also configured to demodulate data or other content received by the at least one antenna 1604. Each transceiver 1602 includes any suitable structure for generating signals for wireless or wired transmission or processing signals received wirelessly or by wire. Each antenna 1604 includes any suitable structure for transmitting or receiving wireless or wired signals. One or multiple transceivers 1602 could be used in the ED 1610, and one or multiple antennas 1604 could be used in the ED 1610. Although shown as a single functional unit, a transceiver 1602 could also be implemented using at least one transmitter and at least one separate receiver.

[0186] The ED 1610 further includes one or more input / output devices 1606 or interfaces (such as a wired interface to the Internet 1650). The input / output devices 1606 facilitate interaction with a user or other devices (network communications) in the network. Each input / output device 1606 includes any suitable structure for providing information to or receiving information from a user, such as a speaker, microphone, keypad, keyboard, display, or touch screen, including network interface communications.

[0187] In addition, the ED 1610 includes at least one memory 1608. The memory 1608 stores instructions and data used, generated, or collected by the ED 1610. For example, the memory 1608 could store software or firmware instructions executed by the processing unit(s) 1600 and data used to reduce or eliminate interference in incoming signals. Each memory 1608 includes any suitable volatile or non-volatile storage and retrieval device(s). Any suitable type of memory can be used, such as random access memory (RAM), read only memory (ROM), hard disk, optical disc, subscriber identity module (SIM) card, memory stick, secure digital (SD) memory card, and the like.FW 6000755PCT02 -45-[oi88] As shown in FIG. 16B, the base station 1670 includes at least one processing unit 1650, at least one transceiver 1652, which includes functionality for a transmitter and a receiver, one or more antennas 1656, at least one memory 1658, and one or more input / output devices or interfaces 1666. A scheduler, which would be understood by one skilled in the art, is coupled to the processing unit 1650. The scheduler could be included within or operated separately from the base station 1670. The processing unit 1650 implements various processing operations of the base station 1670, such as signal coding, data processing, power control, input / output processing, or any other functionality. The processing unit 1650 can also support the methods and teachings described in more detail above. Each processing unit 1650 includes any suitable processing or computing device configured to perform one or more operations. Each processing unit 1650 could, for example, include a microprocessor, microcontroller, digital signal processor, field programmable gate array, or application specific integrated circuit.

[0189] Each transceiver 1652 includes any suitable structure for generating signals for wireless or wired transmission to one or more EDs or other devices. Each transceiver 1652 further includes any suitable structure for processing signals received wirelessly or by wire from one or more EDs or other devices. Although shown combined as a transceiver 1652, a transmitter and a receiver could be separate components. Each antenna 1656 includes any suitable structure for transmitting or receiving wireless or wired signals. While a common antenna 1656 is shown here as being coupled to the transceiver 1652, one or more antennas 1656 could be coupled to the transceiver(s) 1652, allowing separate antennas 1656 to be coupled to the transmitter and the receiver if equipped as separate components. Each memoiy 1658 includes any suitable volatile or non-volatile storage and retrieval device(s). Each input / output device 1666 facilitates interaction with a user or other devices (network communications) in the network. Each input / output device 1666 includes any suitable structure for providing information to or receiving / providing information from a user, including network interface communications .

[0190] FIG. 17 is a block diagram of a computing system 1700 that can be used for implementing the devices and methods disclosed herein, in accordance with some implementations of the present disclosure. For example, the computing system can be any entity of UE, access network (AN), mobility management (MM), session management (SM), user plane gateway (UPGW), or access stratum (AS). Specific devices can utilize all of the components shown or only a subset of the components, and levels of integration can vary from device to device. Furthermore, a device can contain multiple instances of a component, such as multiple processing units, processors, memories,FW 6000755PCT02 -46-transmitters, receivers, etc. The computing system 1700 includes a processing unit 1702. The processing unit includes a central processing unit (CPU) 1714, memory 1708, and can further include a mass storage device 1704, a video adapter 1710, and an I / O interface 1712 connected to a bus 1720.

[0191] The bus 1720 can be one or more of any type of several bus architectures including a memory bus or memory controller, a peripheral bus, or a video bus. The CPU 1714 can comprise any type of electronic data processor. The memory 1708 can comprise any type of non-transitory system memory such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), read-only memory (ROM), or a combination thereof. In an embodiment, the memory 1708 can include ROM for use at boot-up, and DRAM for program and data storage for use while executing programs.

[0192] The mass storage 1704 can comprise any type of non-transitory storage device configured to store data, programs, and other information and to make the data, programs, and other information accessible via the bus 1720. The mass storage 1704 can comprise, for example, one or more of a solid state drive, hard disk drive, a magnetic disk drive, or an optical disk drive.

[0193] The video adapter 1710 and the I / O interface 1712 provide interfaces to couple external input and output devices to the processing unit 1702. As illustrated, examples of input and output devices include a display 1718 coupled to the video adapter 1710 and a mouse, keyboard, or printer 1716 coupled to the I / O interface 1712. Other devices can be coupled to the processing unit 1702, and additional or fewer interface cards can be utilized. For example, a serial interface such as Universal Serial Bus (USB) (not shown) can be used to provide an interface for an external device.

[0194] The processing unit 1702 also includes one or more network interfaces 1706, which can comprise wired links, such as an Ethernet cable, or wireless links to access nodes or different networks. The network interfaces 1706 allow the processing unit 1702 to communicate with remote units via the networks. For example, the network interfaces 1706 can provide wireless communication via one or more transmitt er s / transmit antennas and one or more receivers / receive antennas. In an embodiment, the processing unit 1702 is coupled to a local-area network 1722 or a wide-area network for data processing and communications with remote devices, such as other processing units, the Internet, or remote storage facilities.

[0195] Features disclosed herein in the context of any particular embodiments can also or instead be implemented in other embodiments. Method embodiments, forFW 6000755PCT02 -47-example, can also or instead be implemented in apparatus, system, and / or computer program product embodiments. In addition, although embodiments are described primarily in the context of methods and apparatus, other implementations are also contemplated, for example, as instructions stored on one or more non-transitory computer-readable media. Such media could store programming or instructions to perform any of various methods consistent with the present disclosure.

[0196] It should be appreciated that one or more steps of the embodiment methods provided herein can be performed by corresponding units or modules. For example, a signal can be transmitted by a transmitting unit or a transmitting module. A signal can be received by a receiving unit or a receiving module. A signal can be processed by a processing unit or a processing module. Other steps can be performed by a performing unit or module, a generating unit or module, an obtaining unit or module, a setting unit or module, an adjusting unit or module, an increasing unit or module, a decreasing unit or module, a determining unit or module, a modifying unit or module, a reducing unit or module, a removing unit or module, or a selecting unit or module. The respective units or modules can be hardware, software, or a combination thereof. For instance, one or more of the units or modules can be an integrated circuit, such as field programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs).

[0197] Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the scope of this disclosure. For example, the technique described in this disclosure can include additional or fewer operations than those shown and described and can be carried out or performed in a different order (e.g., similar steps in the reversed order compared to the described order of operations). For another example, steps described herein apply to various sides of network communications (for example, between a base station and a UE or between two UEs), and where steps for one side are disclosed then corresponding steps on the other side are also understood to be disclosed by those of skill in the art. Moreover, the scope of the disclosure is not intended to be limited to the particular embodiments described herein, as one of ordinary skill in the art will readily appreciate from this disclosure that processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, can perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.FW 6000755PCT02 -48-

Claims

WHAT IS CLAIMED IS:

1. A method comprising: receiving, by a user equipment (UE), a configuration from a serving cell group, wherein the configuration indicates a first component carrier (CC) of the serving cell group, a second CC of the serving cell group, a first CC of a candidate cell group, a second CC of the candidate cell group, and a condition for triggering an event, and the condition is based on at least one of a channel quality metric of the first CC of the serving cell group, a channel quality metric of the second CC of the serving cell group, a channel quality metric of the first CC of the candidate cell group, or a channel quality metric of the second CC of the candidate cell group; and transmitting, by the UE, a measurement report to the serving cell group in response to an occurrence of the event based on the condition.

2. The method of claim 1, further comprising: evaluating whether the event occurs based on the at least one of the channel quality metric of the first CC of the serving cell group, the channel quality metric of the second CC of the serving cell group, the channel quality metric of the first CC of the candidate cell group, or the channel quality metric of the second CC of the candidate cell group; receiving a cell switching command from the serving cell group; and performing a cell switching from the serving cell group to the candidate cell group in response to receiving the cell switching command.

3. The method of claim 1 or claim 2, wherein receiving the configuration comprises: receiving one or more radio resource control (RRC) messages, wherein each of the one or more RRC messages comprises at least a portion of the configuration.

4. The method of any of claims 1-3, wherein the serving cell group comprises one or more serving cells, and the candidate cell group comprises one or more candidate cells.

5. The method of any of claims 1-4, wherein the condition for triggering the event comprises: the channel quality metric of the first CC of the candidate cell group is larger than the channel quality metric of the first CC of the serving cell group by a first offset; and the channel quality metric of the second CC of the candidate cell group is larger than the channel quality metric of the first CC of the serving cell group by a second offset.

6. The method of any of claims 1-4, wherein the condition for triggering the event comprises: a larger one of the channel quality metric of the first CC of the candidate cellFW 6000755PCT02 -49-group and the channel quality metric of the second CC of the candidate cell group is larger than the channel quality metric of the first CC of the serving cell group by a first offset; and a difference between the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group is equal to or smaller than a second offset.

7. The method of any of claims 1-4, wherein the condition for triggering the event comprises: the channel quality metric of the first CC of the candidate cell group is larger than a larger one of the channel quality metric of the first CC of the serving cell group and the channel quality metric of the second CC of the serving cell group by a first offset; and the channel quality metric of the second CC of the candidate cell group is larger than the larger one of the channel quality metric of the first CC of the serving cell group and the channel quality metric of the second CC of the serving cell group by a second offset.

8. The method of any of claims 1-4, wherein the condition for triggering the event comprises: the channel quality metric of the first CC of the candidate cell group is larger than a first threshold; and the channel quality metric of the second CC of the candidate cell group is larger than a second threshold.

9. The method of any of claims 1-4, wherein the condition for triggering the event comprises: a larger one of the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group is larger than a threshold; and a difference between the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group is equal to or smaller than a offset.

10. The method of any of claims 1-4, wherein the condition for triggering the event comprises: the channel quality metric of the first CC of the serving cell group is smaller than a first threshold; the channel quality metric of the second CC of the serving cell group is smaller than a second threshold;FW 6000755PCT02 -50-the channel quality metric of the first CC of the candidate cell group is larger than a third threshold; and the channel quality metric of the second CC of the candidate cell group is larger than a fourth threshold.

11. The method of any of claims 1-4, wherein the condition for triggering the event comprises: a larger one of the channel quality metric of the first CC of the serving cell group and the channel quality metric of the second CC of the serving cell group is smaller than a first threshold; and a larger one of the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group is larger than a second threshold.

12. The method of any of claims 1-4, wherein the condition for triggering the event comprises: a larger one of the channel quality metric of the first CC of the serving cell group and the channel quality metric of the second CC of the serving cell group is smaller than a threshold.

13. The method of any of claims 1-12, wherein the configuration further indicates one or more of: a first plurality of reference signals (RSs) associated with the first CC of the serving cell group and the second CC of the serving cell group; a second plurality of RSs associated with the first CC of the candidate cell group and the second CC of the candidate cell group; a first number of CCs, comprising the first CC and the second CC, from the serving cell group; or a second number of CCs, comprising the first CC and the second CC, from the candidate cell group.

14. The method of claim 13, further comprising: determining the channel quality metric of the first CC of the serving cell group and the channel quality metric of the second CC of the serving cell group based on measurements of the first plurality of RSs; and determining the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group based on measurements of the second plurality of RSs.FW 6000755PCT02 -51-15- The method of claim 13, wherein the measurement report indicates one or more RS received power (RSRP) values and one or more identifiers for one or more RSs in the first plurality of RSs and the second plurality of RSs.

16. The method of any of claims 1-15, wherein the channel quality metric of the first CC of the serving cell group comprises a beam level channel quality metric or a CC level channel quality metric.

17. The method of any of claims 1-16, wherein the configuration further indicates a time to trigger (TTT) period, and the method further comprises: determining that the event occurs in response to detecting that the condition for triggering the event is satisfied during the TTT period.

18. The method of any of claims 1-17, wherein the configuration further indicates a threshold, and the method further comprises: selecting one or more reference signals (RSs) associated with the first CC of the serving cell group, the second CC of the serving cell group, the first CC of the candidate cell group, or the second CC of the candidate cell group based on the threshold.

19. The method of any of claims 1-18, wherein transmitting the measurement report comprises: transmitting the measurement report via a physical uplink shared channel (PUSCH) or a physical uplink control channel (PUCCH).

20. A method comprising: transmitting, by a serving cell group, a configuration to a user equipment (UE), wherein the configuration indicates a first component carrier (CC) of the serving cell group, a second CC of the serving cell group, a first CC of a candidate cell group, a second CC of the candidate cell group, and a condition for triggering an event, and the condition is based on at least one of a channel quality metric of the first CC of the serving cell group, a channel quality metric of the second CC of the serving cell group, a channel quality metric of the first CC of the candidate cell group, or a channel quality metric of the second CC of the candidate cell group; and receiving, by the serving cell group, a measurement report from the UE in response to an occurrence of the event based on the condition.

21. The method of claim 20, further comprising: transmitting a cell switching command to the UE.

22. The method of claim 21, wherein transmitting the cell switching command to the UE comprises:FW 6000755PCT02 -52-transmitting the cell switching command to the UE in response to receiving the measurement report from the UE.

23. The method of any of claims 20-22, wherein transmitting the configuration comprises: transmitting one or more radio resource control (RRC) messages, wherein each of the one or more RRC messages comprises at least a portion of the configuration.

24. The method of any of claims 20-23, wherein the serving cell group comprises one or more serving cells, and the candidate cell group comprises one or more candidate cells.

25. The method of any of claims 20-24, wherein the condition for triggering the event comprises: the channel quality metric of the first CC of the candidate cell group is larger than the channel quality metric of the first CC of the serving cell group by a first offset; and the channel quality metric of the second CC of the candidate cell group is larger than the channel quality metric of the first CC of the serving cell group by a second offset.

26. The method of any of claims 20-24, wherein the condition for triggering the event comprises: a larger one of the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group is larger than the channel quality metric of the first CC of the serving cell group by a first offset; and a difference between the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group is equal to or smaller than a second offset.

27. The method of any of claims 20-24, wherein the condition for triggering the event comprises: the channel quality metric of the first CC of the candidate cell group is larger than a larger one of the channel quality metric of the first CC of the serving cell group and the channel quality metric of the second CC of the serving cell group by a first offset; and the channel quality metric of the second CC of the candidate cell group is larger than the larger one of the channel quality metric of the first CC of the serving cell group and the channel quality metric of the second CC of the serving cell group by a second offset.

28. The method of any of claims 20-24, wherein the condition for triggering the event comprises:FW 6000755PCT02 -53-the channel quality metric of the first CC of the candidate cell group is larger than a first threshold; and the channel quality metric of the second CC of the candidate cell group is larger than a second threshold.

29. The method of any of claims 20-24, wherein the condition for triggering the event comprises: a larger one of the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group is larger than a threshold; and a difference between the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group is equal to or smaller than a offset.

30. The method of any of claims 20-24, wherein the condition for triggering the event comprises: the channel quality metric of the first CC of the serving cell group is smaller than a first threshold; the channel quality metric of the second CC of the serving cell group is smaller than a second threshold; the channel quality metric of the first CC of the candidate cell group is larger than a third threshold; and the channel quality metric of the second CC of the candidate cell group is larger than a fourth threshold.

31. The method of any of claims 20-24, wherein the condition for triggering the event comprises: a larger one of the channel quality metric of the first CC of the serving cell group and the channel quality metric of the second CC of the serving cell group is smaller than a first threshold; and a larger one of the channel quality metric of the first CC of the candidate cell group and the channel quality metric of the second CC of the candidate cell group is larger than a second threshold.

32. The method of any of claims 20-24, wherein the condition for triggering the event comprises: a larger one of the channel quality metric of the first CC of the serving cell group and the channel quality metric of the second CC of the serving cell group is smaller than a threshold.FW 6000755PCT02 -54-33- The method of any of claims 20-32, wherein the configuration further indicates one or more of: a first plurality of reference signals (RSs) associated with the first CC of the serving cell group and the second CC of the serving cell group; a second plurality of RSs associated with the first CC of the candidate cell group and the second CC of the candidate cell group; a first number of CCs, comprising the first CC and the second CC, from the serving cell group; or a second number of CCs, comprising the first CC and the second CC, from the candidate cell group.

34. The method of claim 33, wherein the measurement report indicates one or more RS received power (RSRP) values and one or more identifiers for one or more RSs in the first plurality of RSs and the second plurality of RSs.

35. The method of any of claims 20-34, wherein the channel quality metric of the first CC of the serving cell group comprises a beam level channel quality metric or a CC level channel quality metric.

36. The method of any of claims 20-35, wherein the configuration further indicates a time to trigger (TTT) period.

37. The method of any of claims 20-36, wherein the configuration further indicates a threshold, and the UE selects one or more reference signals (RSs) associated with the first CC of the serving cell group, the second CC of the serving cell group, the first CC of the candidate cell group, or the second CC of the candidate cell group based on the threshold.

38. The method of any of claims 20-37, wherein receiving the measurement report comprises: receiving the measurement report via a physical uplink shared channel (PUSCH) or a physical uplink control channel (PUCCH).

39. A method comprising : receiving, by a user equipment (UE), a configuration from a serving cell group, wherein the configuration indicates at least a first timing advance group (TAG) of a candidate cell group and a plurality of component carriers (CCs) of the candidate cell group, and the plurality of CCs comprises at least a first CC associated with the first TAG; and transmitting, by the UE, a random access preamble to the candidate cell group for the first TAG.FW 6000755PCT02 -55-40. The method of claim 39, wherein the plurality of CCs further comprises a second CC associated with a second TAG of the candidate cell group, and the method further comprises: receiving an indication from the serving cell group, wherein the indication indicates a request for a first random access for the first TAG and a second random access for the second TAG, and the indication further indicates the random access preamble, a first random access resource for the first random access, and a second random access resource for the second random access.

41. The method of claim 40, wherein the indication comprises at least one of a physical downlink control channel (PDCCH) order, downlink control information (DCI), or a medium access control (MAC)-control element (CE).

42. The method of claim 39 or claim 40, wherein transmitting the random access preamble to the candidate cell group for the first TAG comprises, in response to receiving the indication: transmitting the random access preamble to the candidate cell group for the first TAG via the first random access resource; and transmitting the random access preamble to the candidate cell group for the second TAG via the second random access resource.

43. The method of any of claims 40-42, wherein the first random access resource comprises one or more of: a first uplink / supplementary uplink (UL / SUL) carrier indicator, a first synchronization signal block (SS / PBCH) index, a first physical random access channel (PRACH) mask index, or a first PRACH retransmission indicator.

44. The method of claim 43, wherein the second random access resource comprises one or more of: a second UL / SUL carrier indicator, a second SS / PBCH index, a second PRACH mask index, or a second PRACH retransmission indicator.

45. The method of any of claims 39-44, wherein: the configuration further indicates a condition for triggering a random access; and the method further comprises: performing measurements on the plurality of CCs; and selecting the first CC from the plurality of CCs based on results of the measurements and the condition, wherein the condition is satisfied on the first CC.

46. The method of claim 45, wherein transmitting the random access preamble to the candidate cell group for the first TAG comprises:FW 6000755PCT02 -56-in response to selecting the first CC, transmitting the random access preamble to the candidate cell group for the first TAG.

47. The method of claim 45, wherein: the condition comprises: a first channel quality metric of one of the plurality of CCs of the candidate cell group is equal to or larger than a first threshold, and a second channel quality metric of a CC of the serving cell group is smaller than a second threshold; and the configuration comprises the first threshold and the second threshold.

48. The method of claim 47, wherein the first channel quality metric is a reference signal received power (RSRP) or a signal-to-interference-plus-noise ratio (SINR).

49. The method of any of claims 39-48, wherein receiving the configuration comprises: receiving one or more radio resource control (RRC) messages, wherein each of the one or more RRC messages comprises at least a portion of the configuration.

50. The method of any of claims 39-49, wherein the serving cell group comprises one or more serving cells, and the candidate cell group comprises one or more candidate cells.

51. The method of any of claims 39-50, further comprising: receiving a response, wherein the response confirms reception of the random access preamble.

52. The method of claim 51, wherein receiving the response comprises: receiving one of a medium access control (MAC)-control element (CE), a group common PDCCH, or a random access response (RAR) command that comprises the response.

53. The method of claim 51 or claim 52, wherein the response indicates at least one of: an index of the random access preamble; an identifier (ID) of the first TAG; or a first time advance (TA) value for the first TAG.

54. The method of any of claims 51-53, wherein the plurality of CCs further comprises a second CC associated with a second TAG of the candidate cell group, and the response indicates a first time advance (TA) value for the first TAG and a second TA value for the second TAG.FW 6000755PCT02 -57-55- The method of any of claims 39-54, wherein the plurality of CCs further comprises a second CC associated with a second TAG of the candidate cell group, and the method further comprises: receiving a cell switching command from the serving cell group, wherein the cell switching command indicates supplementary uplink carrier or uplink carrier for the first TAG, supplementary uplink carrier or uplink carrier for the second TAG, a first timing advance command for the first TAG, a second timing advance command for the second TAG, a first transmission configuration indicator (TCI) state ID for the first TAG, and a second TCI state ID for the second TAG.

56. A method comprising: transmitting, by a serving cell group, a configuration to a user equipment (UE), wherein the configuration indicates at least a first timing advance group (TAG) of a candidate cell group and a plurality of component carriers (CCs) of the candidate cell group, and the plurality of CCs comprises at least a first CC associated with the first TAG; and receiving, by the candidate cell group, a random access preamble from the UE for the first TAG.

57. The method of claim 56, wherein the plurality of CCs further comprises a second CC associated with a second TAG of the candidate cell group, and the method further comprises: transmitting, by the serving cell group, an indication to the UE, wherein the indication indicates a request for a first random access for the first TAG and a second random access for the second TAG, and the indication further indicates the random access preamble, a first random access resource for the first random access, and a second random access resource for the second random access.

58. The method of claim 57, wherein the indication comprises at least one of a physical downlink control channel (PDCCH) order, downlink control information (DCI), or a medium access control (MAC)-control element (CE).

59. The method of claim 57 or claim 58, wherein the first random access resource comprises one or more of: a first uplink / supplementary uplink (UL / SUL) carrier indicator, a first synchronization signal block (SS / PBCH) index, a first physical random access channel (PRACH) mask index, or a first PRACH retransmission indicator.

60. The method of any of claims 57-59, wherein the second random access resource comprises one or more of: a second UL / SUL indicator, a second SS / PBCH index, a second PRACH mask index, or a second PRACH retransmission indicator.FW 6000755PCT02 -58-61. The method of any of claims 56-60, wherein the configuration further indicates a condition for triggering a random access.

62. The method of claim 61, wherein: the condition comprises: a first channel quality metric of one of the plurality of CCs of the candidate cell group is equal to or larger than a first threshold, and a second channel quality metric of a CC of the serving cell group is smaller than a second threshold; and the configuration comprises the first threshold and the second threshold.

63. The method of claim 62, wherein the first channel quality metric is a reference signal received power (RSRP) or a signal-to-interference-plus-noise ratio (SINR).

64. The method of any of claims 56-63, wherein transmitting the configuration comprises: transmitting one or more radio resource control (RRC) messages, wherein each of the one or more RRC messages comprises at least a portion of the configuration.

65. The method of any of claims 56-64, wherein the serving cell group comprises one or more serving cells, and the candidate cell group comprises one or more candidate cells.

66. The method of any of claims 56-65, further comprising: transmitting a response, wherein the response confirms reception of the random access preamble.

67. The method of claim 66, wherein transmitting the response comprises: transmitting one of a medium access control (MAC)-control element (CE), a group common PDCCH, or a random access response (RAR) command that comprises the response.

68. The method of claim 66 or claim 67, wherein the response indicates at least one of: an index of the random access preamble; an identifier (ID) of the first TAG; or a first time advance (TA) value for the first TAG.

69. The method of any of claims 66-68, wherein the plurality of CCs further comprises a second CC associated with a second TAG of the candidate cell group, and the response indicates a first time advance (TA) value for the first TAG and a second TA value for the second TAG.FW 6000755PCT02 -59-70. The method of any of claims 56-69, wherein the plurality of CCs further comprises a second CC associated with a second TAG of the candidate cell group, and the method further comprises: transmitting, by the serving cell group, a cell switching command to the UE, wherein the cell switching command indicates supplementary uplink carrier or uplink carrier for the first TAG, supplementary uplink carrier or uplink carrier for the second TAG, a first timing advance command for the first TAG, a second timing advance command for the second TAG, a first transmission configuration indicator (TCI) state ID for the first TAG, and a second TCI state ID for the second TAG.

71. An apparatus, comprising: at least one processor; and at least one memory coupled to the at least one processor, wherein the at least one memory stores programming instructions that, when executed by the at least one processor, cause the apparatus to perform a method according to any of claims 1-19.

72. A non-transitory computer readable storage medium storing programming instructions that, when executed by at least one processor, cause an apparatus to perform a method according to any of claims 1-19.

73. An apparatus, comprising: at least one processor; and at least one memory coupled to the at least one processor, wherein the at least one memory stores programming instructions that, when executed by the at least one processor, cause the apparatus to perform a method according to any of claims 20-38.

74. A non-transitory computer readable storage medium storing programming instructions that, when executed by at least one processor, cause an apparatus to perform a method according to any of claims 20-38.

75. An apparatus, comprising: at least one processor; and at least one memory coupled to the at least one processor, wherein the at least one memory stores programming instructions that, when executed by the at least one processor, cause the apparatus to perform a method according to any of claims 39-55.

76. A non-transitory computer readable storage medium storing programming instructions that, when executed by at least one processor, cause an apparatus to perform a method according to any of claims 39-55.FW 6000755PCT02 -60-77. An apparatus, comprising: at least one processor; and at least one memory coupled to the at least one processor, wherein the at least one memory stores programming instructions that, when executed by the at least one processor, cause the apparatus to perform a method according to any of claims 56-70.

78. A non-transitory computer readable storage medium storing programming instructions that, when executed by at least one processor, cause an apparatus to perform a method according to any of claims 56-70.FW 6000755PCT02 -61-

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