Systems and methods for enhancing user experience under multiple timing advance group configurations

Abstract

Systems and methods for enhancing user experience in multiple timing advance group (TAG) configurations are disclosed herein. In various embodiments, a user equipment (UE) configured with a primary component carrier (PCC) of a first TAG and a secondary component carrier (SCC) of a second TAG may be configured to trigger, after a first random access channel (RACH) procedure fails, a second such RACH procedure on the SCC for uplink (UL) synchronization of the SCC. The UE may trigger the second RACH procedure upon identifying any one of: a measurement report reporting a reference signal received power (RSRP) of the SCC; a channel state information (CSI) report reports a first CSI component of the SCC that is above a threshold, and / or downlink (DL) throughput through the SCC has been improved for a first time period.

Description

Technical Field

[0001] This application relates in general to wireless communication systems, including wireless communication systems that use carrier aggregation (CA) with carriers of different timing advance groups (TAGs). Background Technology

[0002] Wireless mobile communication technologies use various standards and protocols to transmit data between base stations and wireless communication devices. For example, wireless communication system standards and protocols may include, for instance, 3GPP Long Term Evolution (LTE) (e.g., 4G), 3GPP New Radio (NR) (e.g., 5G), and the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard for Wireless Local Area Networks (WLANs) (often referred to as Wi-Fi within the industry organization). ® ).

[0003] As envisioned by 3GPP, different wireless communication system standards and protocols can use various radio access networks (RANs) for communication between RAN base stations (sometimes also commonly referred to as RAN nodes, network nodes, or simply nodes) and wireless communication equipment called user equipment (UEs). 3GPP RANs can include, for example, Global System for Mobile Communications (GSM), Enhanced Data Rate GSM Evolution (EDGE) RAN (GERAN), Universal Terrestrial Radio Access Network (UTRAN), Evolved Universal Terrestrial Radio Access Network (E-UTRAN), and / or Next Generation Radio Access Network (NG-RAN).

[0004] Each RAN can use one or more Radio Access Technologies (RATs) to perform communication between the base station and the UE. For example, GERAN implements the GSM and / or EDGE RAT, UTRAN implements the Universal Mobile Telecommunications System (UMTS) RAT or other 3GPP RATs, E-UTRAN implements the LTE RAT (sometimes simply referred to as LTE), and NG-RAN implements the NR RAT (this NR RAT is sometimes referred to herein as the 5G RAT, 5G NR RAT, or simply NR). In some deployments, E-UTRAN may also implement the NR RAT. In some deployments, NG-RAN may also implement the LTE RAT.

[0005] The base stations used by a RAN can correspond to that RAN. An example of an E-UTRAN base station is an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node B (also commonly referred to as Evolved Node B, Enhanced Node B, eNodeB, or eNB). An example of an NG-RAN base station is a Next Generation Node B (sometimes also called gNodeB or gNB).

[0006] The RAN provides communication services to external entities through its connection with the core network (CN). For example, E-UTRAN can utilize the evolved packet core (EPC), while NG-RAN can utilize the 5G core network (5GC).

[0007] 5G NR frequency bands can be divided into two or more distinct frequency ranges. For example, Frequency Range 1 (FR1) may include bands operating at frequencies below 6 GHz, some of which are available for previous standards and can potentially be extended to cover new spectrum offerings from 410 MHz to 7125 MHz. Frequency Range 2 (FR2) may include bands from 24.25 GHz to 52.6 GHz. It should be noted that in some systems, FR2 may also include bands from 52.6 GHz to 71 GHz (or higher). Bands in the millimeter-wave (mmWave) range of FR2 may have smaller coverage areas but potentially higher available bandwidth than bands in FR1. Those skilled in the art will recognize that these frequency ranges, presented by way of example, may change over time or in different regions. Summary of the Invention

[0008] Some aspects of this disclosure relate to a method for a user equipment (UE) in a radio resource control (RRC) connection mode with a network via a primary component carrier (PCC) of a first timing advance group (TAG) of the network, the method comprising: identifying a first failure of a first random access channel (RACH) procedure for uplink (UL) synchronization of a secondary component carrier (SCC) configured for the UE for a second TAG of the network; identifying that a first measurement report generated by the UE for the network reports a first reference signal received power (RSRP) of the SCC; and triggering a second RACH procedure for UL synchronization of the SCC on the SCC in response to identifying the first failure of the first RACH procedure for UL synchronization of the SCC and identifying that the first measurement report reports the first RSRP of the SCC.

[0009] Some aspects of this disclosure relate to an apparatus for a user equipment (UE), the apparatus comprising: a baseband processor; and a memory storing instructions, which, when executed by the baseband processor, configure the apparatus to: when the UE is in a Radio Resource Control (RRC) connection mode with the network via a primary component carrier (PCC) of a first timing advance group (TAG) of the network: identify a first failure of a first random access channel (RACH) procedure for uplink (UL) synchronization of a secondary component carrier (SCC) configured for the UE for a second TAG of the network; identify that a first channel state information (CSI) report generated by the UE for the network reports a first CSI component for the SCC that meets a threshold; and trigger a second RACH procedure for UL synchronization of the SCC on the SCC in response to the first failure of the first RACH procedure for the UL synchronization of the SCC and the identification that the first CSI report reports a first CSI component for the SCC that exceeds the threshold.

[0010] Some aspects of this disclosure relate to a non-transitory computer-readable storage medium comprising instructions that, when executed by one or more processors of a user equipment (UE) in a Radio Resource Control (RRC) connection mode with the network via a primary component carrier (PCC) of a first timing advance group (TAG) of the network, cause the UE to: identify a first failure of a first random access channel (RACH) procedure for uplink (UL) synchronization of a secondary component carrier (SCC) configured for the UE for a second TAG of the network; identify that downlink (DL) throughput through the SCC has improved in a first time period; and, in response to identifying the first failure of the first RACH procedure for UL synchronization of the SCC and identifying that the DL throughput through the SCC has improved in the first time period, trigger a second RACH procedure for UL synchronization of the SCC on the SCC. Attached Figure Description

[0011] To facilitate the identification of any particular element or action in the discussion, one or more of the most significant digits in the figure reference numerals refer to the figure number in which the element was first introduced.

[0012] Figure 1 A flowchart illustrating the signaling between the UE and the network base station is provided.

[0013] Figure 2 A flowchart illustrating the signaling between the UE and the network base station is provided.

[0014] Figure 3A flowchart illustrating a use case for determining whether UL synchronization for SCC can be optimized based on SCC measurement reports is available.

[0015] Figure 4 A flowchart illustrating a use case for determining whether UL synchronization for SCC can be optimized based on CSI reports for SCC is provided.

[0016] Figure 5 A flowchart illustrating a use case for determining whether UL synchronization for SCC can be optimized based on CSI reports for SCC is provided.

[0017] Figure 6 An example is given of a method for a PCC of the first tag of the network to connect to a UE in RRC connection mode of the network, according to the implementation scheme discussed herein.

[0018] Figure 7 An example is given of a method for a PCC of the first tag of the network to connect to a UE in RRC connection mode of the network, according to the implementation scheme discussed herein.

[0019] Figure 8 An example is given of a method for a PCC of the first tag of the network to connect to a UE in RRC connection mode of the network, according to the implementation scheme discussed herein.

[0020] Figure 9 An example architecture of a wireless communication system according to the implementation scheme disclosed herein is illustrated.

[0021] Figure 10 A system for performing signaling between a wireless device and a network device according to an embodiment disclosed herein is illustrated. Detailed Implementation

[0022] Various implementations are described with respect to the UE. However, references to the UE are provided for illustrative purposes only. The example implementations can be used with any electronic component that can establish a connection to a network and is configured with hardware, software, and / or firmware for exchanging information and data with the network. Therefore, the UE as described herein is used to represent any suitable electronic component.

[0023] This discussion concerns UL synchronization of a UE with respect to a component carrier (CC) of a cell operating with that UE. As will be understood, a cell in a wireless communication system can be expected to operate with multiple UEs simultaneously. The corresponding propagation timing of UL signaling from each UE to the cell's receiving point on the cell's CC will vary depending on various factors such as the UE's distance from the receiving point, the signal path, etc., as applicable at each UE. It is beneficial for the network to synchronize the arrival times of UL signals from these various UEs at the physical location of the cell's receiving point in order to minimize perceived interference of these UL signals at the cell. This is accomplished by configuring each UE (operating with the cell) (individually) with appropriate timing advance (TA) information, which the UE uses to determine the amount of time by which it should advance the transmission of its UL signaling. Through this mechanism, from the cell's perspective, the arrival of the UE's UL signaling is synchronized with the arrival of other UL signaling from other UEs.

[0024] A TA value for the cell can be established at the UE via a Random Access Channel (RACH) procedure. As part of the RACH procedure, the UE transmits a random access preamble on the cell's CC. The cell responds with a Random Access Response (RAR), which sets / adjusts the cell TA value that the UE will transmit on the cell's CC. Note that this behavior can occur when using a 4-step RACH or a 2-step RACH procedure.

[0025] From the UE's perspective, the TA values ​​for various CCs / cells can be understood on the basis of Timing Advance Groups (TAGs). The UE can understand that one or more cells belong to the same TAG, and a given TA value associated with that TAG will be used for UL transmission on the CC of any cell in that TAG. Organizing TA values ​​in this way into TAGs corresponding to cells allows the UE to configure relative to cells with similar positioning (e.g., co-location) without explicitly requiring separate TA configuration for each such cell in each case (e.g., by simply changing the TA values ​​of the TAG as a whole).

[0026] In some uplink (UL) carrier aggregation (ULCA) scenarios, where two or more CCs are used by a single UE for UL communication, the aggregated CCs may be used for cells belonging to different tags. As an example, this might be the case when considering ULCA between FDD cells in a “hybrid” frequency division duplex (FDD) + dynamic spectrum sharing (DSS) configuration, corresponding to the coexistence of FDD DSS and LTE / NR.

[0027] The UE can support the use of multiple TAGs in such situations. For example, the multi-TAG function enables the UE to independently perform UL synchronization for each CC in one or more secondary CCs (SCCs) of the primary cell (PCell) of the first TAG, as well as for the secondary cells (SCells) used for UL in other TAGs, based on ULCA operation.

[0028] The UE can use the Capability Information Element (IE) to indicate to the network that it supports multiple tags. In some wireless communication systems, supportedNumberTAG n2,n3,n4 IE can be used for this purpose.

[0029] Corresponding to such multi-TAG scenarios for ULCA, it is possible that after the UE enters the connected radio resource control (RRC) state with the network on the PCC of the PCell and after the initial activation / configuration of the SCC of the SCell, the UE attempts to establish UL synchronization for the SCC via the Physical Downlink Control Channel (PDCCH) Ordered Contention-Free Random Access (CFRA) procedure on the SCC. In some such cases, the Physical Random Access Channel (PRACH) (e.g., RACH preamble, msg1 / msgA) is transmitted by the UE to the SCell on the SCC, while the RAR (e.g., msg2 or msgB) including any TA information about the SCell is transmitted by the PCell to the UE on the PCC.

[0030] It should be noted that in some such cases, messages corresponding to the 4-step RACH procedure (msg1, msg2) can be used (as just described). In such cases, the contention resolution messages corresponding to the 4-step RACH procedure (msg3 / msg4) may not be necessary (because the RACH procedure can be considered as corresponding to the CFRA procedure using the PDCCH command).

[0031] It should be noted that the process described above assumes that the UE and SCC have sufficiently good channel conditions to independently achieve synchronization with the network base station for that SCC, thereby serving the corresponding SCell. In other words, for the above SCC synchronization to be achieved, the channel conditions of the SCC must be good enough that the UE can both decode the PDCCH commands received from the SCell on that SCC and transmit sufficient RACH preambles to the SCell on that SCC.

[0032] Figure 1A flowchart 100 illustrates the signaling between UE 102 and network base station 104. From the perspective of UE 102, base station 104 operates PCC 106 of UE's PCell and SCC 108 of UE's SCell, as shown in the figure. From the perspective of UE 102, PCC 106 and SCC 108 belong to different tags.

[0033] First, base station 104 establishes an RRC connection 112 with UE 102 via PCC 106. Base station 104 communicates with UE 102 via PCC 106 to configure UE 102 to use a ULCA with both PCC 106 and SCC 108. Corresponding to this configuration, base station 104 activates SCC 108 for use at / by UE 102.

[0034] Subsequently, since PCC 106 and SCC 108 are in different tags, base station 104 transmits PDCCH command 114 to UE 102 to perform RACH procedure on SCC 108 to achieve independent UL synchronization for SCC 108.

[0035] In response to PDCCH command 114, UE 102 triggers RACH procedure 116 for UL synchronization on SCC 108. As shown, as part of RACH procedure 116, UE 102 transmits PRACH 120 (e.g., random access preamble) to base station 104 on SCC 108. Based on the timing of PRACH 120, base station 104 determines TA information for UE 102 to use for UL communication on SCC 108. This TA information is provided from base station 104 to UE 102 in RAR 122 transmitted on base station 104. UE 102 uses this TA information to determine the TA value for UL transmission synchronization on SCC 108.

[0036] It should be noted that PRACH 120 and RAR 122 can be messages corresponding to either a 2-step RACH procedure or a 4-step RACH procedure. In the case of messages corresponding to a 4-step RACH procedure, the contention resolution messages (msg3 / msg4) may not be necessary within RACH procedure 116 (because in this case RACH procedure 116 is a CFRA procedure).

[0037] If RACH procedure 116 is successful, the UE now synchronizes UL transmissions on SCC 108, thus successfully establishing ULCA 118 using both PCC 106 and SCC 108 at UE 102. Therefore, UE 102 is able to transmit the first UL data 124 to base station 104 on PCC 106 and the second UL data 126 to base station 104 on SCC 108 simultaneously.

[0038] Figure 1 This corresponds to the scenario where the UE is within sufficient coverage for a successful RACH procedure 116. However, various conditions under which this assumption may not hold are possible. For example, if the UE is in certain cell center area conditions for aggregated carriers (e.g., approximately -115 dBm), the signal strength may be high enough for the network to activate the DL aggregated carriers via PCell and SCell. However, it is possible that the corresponding UL signal-to-interference-plus-noise ratio (SINR) is still not high enough, causing the UL transmission made by the UE on the SCC of the SCell to fail to be successfully decoded at the base station. Therefore, in such cases, it may happen that the UE successfully decodes the PDCCH command in the DL transmitted on the SCC to trigger the RACH procedure for UL synchronization on the SCC, but the corresponding PRACH transmitted by the UE on the SCC that has triggered the RACH procedure fails to reach the network.

[0039] Figure 2 A flowchart 200 illustrates the signaling between UE 202 and network base station 204. From the perspective of UE 202, base station 204 operates PCC 206 of UE's PCell and SCC 208 of UE's SCell, as shown in the figure. From the perspective of UE 202, PCC 206 and SCC 208 belong to different tags.

[0040] First, base station 204 establishes an RRC connection 212 with UE 202 via PCC 206. Base station 204 communicates with UE 202 via PCC 206 to configure UE 202 to use a ULCA with both PCC 206 and SCC 208. Corresponding to this configuration, base station 204 activates SCC 208 for use by / at UE 202.

[0041] Subsequently, because PCC 106 and SCC 108 are in different tags, base station 204 transmits PDCCH command 214 to UE 202 to perform a RACH procedure on SCC 208 for independent UL synchronization for SCC 208. The channel conditions on SCC 208 for UE 202 are sufficient to allow DL signaling (such as PDCCH command 214) on SCC 208 to be received at UE 202.

[0042] In response to PDCCH command 214, UE 202 triggers RACH procedure 216 for UL synchronization on SCC 208. As shown, as part of RACH procedure 216, UE 202 transmits PRACH 220 (e.g., random access preamble) to base station 204 on SCC 208. However, the channel conditions on SCC 208 for UE 202 are insufficient for UL signaling (such as PRACH 220) from UE 202 on SCC 208 to be successfully received at base station 104. Therefore, PRACH 220 is not successfully received at base station 104. Note that because PRACH 220 did not reach base station 104, base station 104 does not send a RAR for PRACH 220.

[0043] Since no RAR was received for PRACH 220, the UE knows it should try another PRACH. Therefore, UE202 can retry PRACH 220 until the PRACH attempt limit is reached. Figure 2 This illustrates a scenario where neither the initial PRACH 220 nor any retry 222 is successfully received at the network (and therefore no RAR is transmitted to UE 202).

[0044] Because RACH procedure 216 failed, the UE did not synchronize the UL transmission on SCC 208. Therefore, ULCA 218 using both PCC 206 and SCC 208 was not successfully established at UE 202. Thus, although UE 202 can transmit the first UL data 224 to base station 204 on PCC 206, due to the lack of UL synchronization for SCC 208, the UE cannot transmit the second UL data 226 to base station 204 on SCC 208, as shown in the figure. Therefore, ULCA 218 using PCC 206 and SCC 208 fails.

[0045] The UE can be configured to perform only a limited number of PRACH attempts corresponding to a triggered RACH procedure for which no RAR has been received from the network (only retrying a limited number of RACH preambles). For example, in some cases, a maximum of 10 RACH preambles corresponding to a triggered RACH procedure can be transmitted. Once the maximum is reached, further PRACH attempts corresponding to the RACH procedure are stopped. The duration corresponding to this limited number of PRACH attempts can be on the order of milliseconds (ms) (e.g., in some cases, a maximum of 10 PRACH attempts can be attempted over a period of 200 ms).

[0046] On the other hand, the duration of the channel condition improvement at the UE can be on the order of seconds, minutes, or longer. For example, the time required for a user to move from 1) a cell center condition where the UE can successfully receive the PDCCH command but the UL SINR is insufficient for the network to receive the RACH preamble transmitted by the UE, to 2) a cell closer condition where the UL SINR is improved and the RACH preamble transmitted by the UE can be successfully received, may be on the order of seconds or minutes.

[0047] Therefore, it has been recognized that in various instances where the SCC and PCC belong to different TAGs (and thus require separate UL synchronization for the SCC), and after receiving the PDCCH command for the RACH procedure to perform UL synchronization for the SCC, by the time the user enters a channel with a sufficiently high UL SINR for the PRACH on the SCC for successful decoding of the UL synchronization by the network, the UE has already reached the PRACH attempt limit for the RACH procedure (and therefore no longer attempts to establish UL synchronization for the SCC via the RACH procedure). Therefore, the UE ultimately does not obtain UL synchronization for the SCC. In such cases, the UE cannot use UL transmission on the SCC according to its ULCA configuration (although in fact the UE now enjoys sufficient channel quality to meet the UL synchronization requirements).

[0048] Furthermore, the UE can be configured so that it does not consider any new opportunities to trigger synchronization for SCC UL until it first drops to RRC idle or no data state and subsequently recovers to RRC connected state via PCC on the PCell. Until then, the user experience (e.g., UL throughput) is limited to the range without SCC.

[0049] This document describes an implementation scheme that can be deployed at the UE, allowing the UE to retry previously failed UL synchronization on the SCC without first exiting the RRC connection state. By using such a mechanism, the time period during which the user experience at the UE (e.g., UL throughput) is limited to the range without the use of the SCC can be relatively shortened.

[0050] It should be understood that the network may (for example, by default) configure the UE for event-based measurement reporting based on measurements from neighboring cells and / or serving cells. In some such cases, the device may be configured to, for example, report the RSRP once the reference signal received power (RSRP) of the cell's CC rises above a certain threshold.

[0051] It is possible that using this threshold in this way also indicates that the corresponding UL SINR at the cell's receiving point is expected to allow successful decoding of the RSRP value sent from the UE to the network's UL on the cell's CC.

[0052] The UE can be configured to initially identify whether the RACH procedure for UL synchronization with the SCC has failed (and thereby indicate that the UE has not achieved UL synchronization with the SCC). The UE can be further configured to indicate that it has been triggered to transmit an RSRP report for the SCC because the RSRP of the SCC has risen above the applicable measurement reporting threshold. In such cases, the UE can use the triggering of the RSRP report for the SCC as a reason for the UE to (also) trigger a new RACH procedure on the SCC to achieve UL synchronization with the SCC.

[0053] As discussed above, since the RSRP of the SCC meets at least the reporting threshold, the new RACH procedure is now expected to succeed. If so, the UE achieves UL synchronization with the SCC and can use the SCC according to the configured ULCA. Therefore, by fully utilizing uplink carrier aggregation (ULCA), the user experience (e.g., higher UL throughput) can be improved immediately when the UE has good channel conditions on the SCC, without requiring the UE to first establish a loop with the network via RRC (e.g., at some later time).

[0054] If the new RACH procedure fails to establish UL synchronization for SCC for the UE under any circumstances, the procedure can be repeated the next time a measurement report event for SCC is triggered.

[0055] Figure 3 Flowchart 300 illustrates a use case for determining whether UL synchronization for SCC based on SCC measurement reports can be optimized. First, it is determined whether the network supports the use of multi-TAG features (302). If not, flowchart 300 ends at point 316 where optimization is not used.

[0056] Then, determine whether the 304 UE supports the use of multiple TAG features (e.g., UE supports reporting). supportedNumberTAG n2,n3,n4 (etc.). If not, flowchart 300 ends at point 316 without using optimization.

[0057] Next, determine whether 306 has already configured ULCA using both PCC and SCC to the UE. If not, flowchart 300 ends at optimization 316 without using.

[0058] Next, determine whether 308 sets the measurement report (e.g., event-based measurement report) to SCC occurrence for SCell. If not, flowchart 300 ends at 316 without using optimization.

[0059] Then, determine if there is a case in 310 that corresponds to the RACH failure on SCC. If not, flowchart 300 ends at point 316 without using optimization.

[0060] Flowchart 300 then proceeds to monitoring 312 to measure SCC for use in measurement reporting (e.g., when the RSRP of SCC rises above a given threshold).

[0061] Subsequently, as shown in the figure, when the measurement report corresponding to monitoring 312 reports for SCC (e.g., reports the RSRP of SCC), 314 can be triggered for RACH for UE UL synchronization for SCC.

[0062] It should be understood that the UE may periodically report the channel conditions for SCC based on Channel State Information (CSI). The CSI report may inform the network of one or more aspects of the channel used for SCC, as perceived by the UE. The CSI report corresponding to the state of SCC in SCell may be transmitted from the UE to the network on PCC in PCell.

[0063] A CSI report may include one or more CSI components. The first CSI component may be a Predecoder Matrix Indicator (PMI) indicating the UE's selection for the predecoder. The second CSI component may be a Channel Quality Index (CQI) indicating the UE's selection for the coding rate and / or modulation scheme. The third CSI component may be a Rank Indicator (RI) indicating the UE's selection for the transmission rank.

[0064] It is possible that one or more aspects of the cell channel reported by the corresponding CSI component may or may not correspond to the cell's quality level, at which the corresponding UL SINR at the cell's receiving point is expected to allow successful decoding of the UL transmission from the UE to the network on the cell's CC.

[0065] This article discusses the comparison between CSI components and their “thresholds.” In this case, it can be understood that the threshold for a particular type of CSI component can be consistent with the perception of that type of CSI component.

[0066] For example, when the CSI component is PMI, the corresponding threshold could be a PMI threshold. When, for example, the PMI indication is interpreted as a pre-decoder corresponding to the cell's quality level, the PMI threshold can be considered satisfied, at which quality level, the corresponding UL SINR at the cell receiver point can be expected to allow successful decoding of the UL transmission from the UE to the network on the cell's CC. This could correspond to, for example, the UE using PMI to indicate a relatively more complex pre-decoder.

[0067] For example, when the CSI component is CQI, the corresponding threshold can be a CQI threshold. When, for example, the CQI indication is interpreted as corresponding to the coding rate and / or modulation scheme of the cell's quality level, the CQI threshold can be considered satisfied. At this quality level, it is expected that the corresponding UL SINR at the cell receiver point allows successful decoding of the UL transmission from the UE to the network on the cell's CC. This could correspond to, for example, the UE using CQI to indicate a relatively high coding rate and / or modulation scheme.

[0068] For example, when the CSI component is RI, the corresponding threshold can be the RI threshold. For instance, when the RI indication is interpreted as corresponding to the rank of the cell's quality level, the RI threshold can be considered satisfied. At this quality level, it is expected that the corresponding UL SINR at the cell's receiver point will allow successful decoding of the UL transmission from the UE to the network on the cell's CC. This could correspond to, for example, the UE using RI to indicate a relatively high rank.

[0069] The UE can be configured to initially identify whether the RACH procedure for UL synchronization with the SCC has failed (and thereby indicate that the UE has not achieved UL synchronization with that SCC). The UE can be further configured to identify that the CSI report reports one or more CSI components of the SCC that meet the applicable threshold. In such a case, the UE can use the identification of one or more CSI components of the SCC meeting the applicable threshold in the CSI report for the network as the reason for the UE to (also) trigger a new RACH procedure on the SCC to achieve UL synchronization with the SCC.

[0070] As discussed above, since one or more CSI components meet their applicable thresholds, the new RACH procedure is now expected to succeed. If so, the UE achieves UL synchronization with the SCC and can use the SCC according to the configured ULCA. Therefore, by fully utilizing uplink carrier aggregation (ULCA), the user experience (e.g., higher UL throughput) can be improved immediately when the UE has good channel conditions on the SCC, without requiring the UE to first establish a loop with the network via RRC (e.g., at some later time).

[0071] If the new RACH procedure fails to establish UL synchronization for SCC for the UE under any circumstances, the procedure can be repeated when the CSI component reported for SCC next meets the corresponding threshold.

[0072] Figure 4 Flowchart 400 illustrates a use case for determining whether UL synchronization for SCC can be optimized based on the CSI report for SCC. First, it is determined whether the network supports the use of the multi-TAG feature. If not, flowchart 400 ends at 416 where optimization is not used.

[0073] Then, determine whether the 404 UE supports the use of multiple TAG features (e.g., whether the UE supports reporting). supportedNumberTAG n2,n3,n4 (etc.). If not, flowchart 400 ends at point 416 without using optimization.

[0074] Next, determine whether ULCA using both PCC and SCC has been configured to the UE in 406. If not, flowchart 400 ends at 416 without optimization.

[0075] Then, determine whether 408 is a CSI report configured for the SCC of the SCell (e.g., via cross-carrier CSI reporting). If not, flowchart 400 ends at 416 without optimization.

[0076] Then, determine if there is a case corresponding to the RACH failure on SCC at 410. If not, flowchart 400 ends at 416 without using optimization.

[0077] Flowchart 400 then proceeds to monitoring 412 the CSI report for SCC (e.g., to identify whether / when the CSI component of the CSI report for SCC meets the applicable threshold).

[0078] Subsequently, as shown in the figure, when the CSI report for SCC includes one or more CSI components that meet the applicable thresholds (e.g., PMI meets the PMI threshold, CQI meets the CQI threshold, and / or RI meets the RI threshold), RACH 414 for UL synchronization of UE for SCC can be triggered.

[0079] In some cases, the UE can monitor its DL throughput over time. Correspondingly, the UE can identify whether the DL throughput via SCC has improved over a given time period. For example, the UE can determine the percentage improvement in DL throughput over a time period / corresponding to the DL throughput over that time period (e.g., based on an improvement of X%). The UE can compare the percentage improvement in DL throughput to a threshold.

[0080] The UE can be configured to initially identify whether the RACH procedure for UL synchronization with the SCC has failed (and thereby indicate that the UE has not achieved UL synchronization with the SCC). The UE can be further configured to identify that DL throughput through the SCC has improved over a period of time. In some such cases, the UE identifies improved DL throughput through the SCC by determining a percentage improvement in DL throughput over that period of time, and further verifying that the percentage improvement in DL throughput meets a DL throughput percentage improvement threshold. In some implementations, the period used for these determinations is the period from the start of the failed RACH procedure.

[0081] The UE can use the identification of improved DL throughput as a reason to trigger a new RACH procedure on the SCC to achieve UL synchronization for the SCC (e.g., based on the assumption that an improvement in DL throughput on a certain channel is likely to be correlated with an improvement in UL throughput on that channel). Due to the identified improvement in DL throughput on the SCC, the new RACH procedure on that SCC is expected to succeed. If so, the UE achieves UL synchronization with the SCC and can use the SCC according to the configured ULCA. Therefore, by fully utilizing uplink carrier aggregation (ULCA), the user experience (e.g., higher UL throughput) can be improved immediately when the UE has good channel conditions on the SCC, without requiring the UE to first establish a loop with the network via RRC (e.g., at some later time).

[0082] If the new RACH procedure fails to establish UL synchronization for SCC for the UE under any circumstances, the procedure can be repeated the next time the aforementioned DL throughput improvement is identified.

[0083] Figure 5 Flowchart 500 illustrates a use case for determining whether UL synchronization for SCC can be optimized based on the CSI report for SCC. First, it is determined whether the network supports the use of multi-TAG features (502). If not, flowchart 500 ends at point 516 where optimization is not used.

[0084] Then, determine whether the 504 UE supports the use of multiple TAG features (e.g., UE supports reporting). supportedNumberTAG n2,n3,n4 (etc.). If not, flowchart 500 ends at point 516 without using optimization.

[0085] Next, determine whether 506 has already configured ULCA using both PCC and SCC to the UE. If not, flowchart 500 ends at optimization 516 without using ULCA.

[0086] Next, determine whether UE 508 is able to track the peak DL throughput level of SCC (and in some cases, PCC). If not, flowchart 500 ends at 516 without using optimization.

[0087] Then, determine if there is a case in 510 that corresponds to the RACH failure on SCC. If not, flowchart 500 ends at 516 without using optimization.

[0088] Flowchart 500 then proceeds to monitoring the DL throughput on SCC 512 to identify improvements in DL throughput on that SCC over the applicable time period.

[0089] Subsequently, as shown in the figure, when the DL throughput on the identified SCC improves during the applicable time period, 514 can be triggered for RACH for UE UL synchronization with the SCC.

[0090] Figure 6 A method 600 is illustrated for a PCC of a first TAG of the network and a UE in RRC connection mode of the network, according to the implementation discussed herein. Method 600 includes identifying 602 a first failure of a first RACH procedure for UL synchronization of the SCC configured for the UE with respect to a second TAG of the network. Method 600 also includes identifying 604 a first measurement report generated by the UE for the network reporting a first RSRP of the SCC. Method 600 further includes triggering 606 a second RACH procedure for UL synchronization of the SCC on the SCC in response to identifying the first failure of the first RACH procedure for UL synchronization of the SCC and identifying the first measurement report reporting the first RSRP of the SCC.

[0091] In some implementations, method 600 further includes: identifying a second failure of the second RACH procedure for UL synchronization of the SCC; identifying that a second measurement report generated by the UE for the network reported a second RSRP of the SCC; and triggering a third RACH procedure for UL synchronization of the SCC on the SCC in response to identifying the second failure of the second RACH procedure for UL synchronization of the SCC and identifying that the second measurement report reported a second RSRP of the SCC.

[0092] Figure 7A method 700 is illustrated for a PCC of a first TAG of the network and a UE in RRC connection mode of the network, according to the implementation discussed herein. Method 700 includes identifying 702 a first failure of a first RACH procedure for UL synchronization of a second TAG of the network configured for the UE's SCC. Method 700 also includes identifying 704 a first CSI report generated by the UE for the network reporting a first CSI component for the SCC that meets a threshold. Method 700 further includes triggering 706 a second RACH procedure for UL synchronization of the SCC on the SCC in response to identifying the first failure of the first RACH procedure for UL synchronization of the SCC and identifying the first CSI report reporting a first CSI component for the SCC that exceeds a threshold.

[0093] In some implementations of method 700, the first CSI component includes a channel quality index (CQI), the threshold includes a CQI threshold, and the second RACH process is triggered in response to determining that the CQI meets the CQI threshold.

[0094] In some embodiments of method 700, the first CSI component includes a predecoder matrix indicator (PMI), the threshold includes a PMI threshold, and the second RACH process is triggered in response to determining that the PMI meets the PMI threshold.

[0095] In some embodiments of method 700, the first CSI component includes RI, the threshold includes an RI threshold, and the second RACH process is triggered in response to determining that RI meets the RI threshold.

[0096] In some implementations, method 700 further includes: identifying a second failure of the second RACH procedure for UL synchronization of the SCC; identifying that a second CSI report generated by the UE for the network reported a second CSI component for the SCC that met a threshold; and triggering a third RACH procedure for UL synchronization of the SCC on the SCC in response to identifying the second failure of the second RACH procedure for UL synchronization of the SCC and identifying that the second CSI report reported a second CSI component for the SCC that exceeded a threshold.

[0097] Figure 8A method 800 is illustrated for a PCC of a first TAG of the network and a UE in RRC connection mode of the network, according to the implementation scheme discussed herein. Method 800 includes identifying 802 a first failure of a first RACH procedure for UL synchronization of a second TAG of the network configured for the UE's SCC. Method 800 also includes identifying 804 that DL throughput through the SCC has improved in a first time period. Method 800 further includes triggering 806 a second RACH procedure for UL synchronization of the SCC on the SCC in response to identifying the first failure of the first RACH procedure for UL synchronization of the SCC and identifying that DL throughput through the SCC has improved in the first time period.

[0098] In some implementations of method 800, identifying that the DL throughput through SCC has improved in the first time period includes: determining the percentage improvement in DL throughput through SCC in the first time period; and determining that the percentage improvement in DL throughput meets the DL throughput percentage improvement threshold.

[0099] In some implementations of method 800, the first time period begins with the first RACH process.

[0100] In some implementations, method 800 further includes: identifying a second failure of the second RACH process for UL synchronization of the SCC; identifying that the DL throughput through the SCC has improved in a second time period; and triggering a third RACH process for UL synchronization of the SCC on the SCC in response to identifying the second failure of the second RACH process for UL synchronization of the SCC and identifying that the DL throughput through the SCC has improved in a second time period.

[0101] Figure 9 An example architecture of a wireless communication system 900 according to an embodiment disclosed herein is illustrated. The following description is provided for an example wireless communication system 900 operating in conjunction with LTE system standards and / or 5G or NR system standards provided by 3GPP technical specifications.

[0102] like Figure 9 As shown, the wireless communication system 900 includes UE 902 and UE 904 (but any number of UEs may be used). In this example, UE 902 and UE 904 are exemplified as smartphones (e.g., handheld touchscreen mobile computing devices capable of connecting to one or more cellular networks), but may also include any mobile or non-mobile computing device configured for wireless communication.

[0103] UE 902 and UE 904 can be configured to be communicatively coupled to RAN 906. In an implementation, RAN 906 can be NG-RAN, E-UTRAN, etc. UE 902 and UE 904 utilize connections (or channels) with RAN 906 (shown as connection 908 and connection 910, respectively), where each connection (or channel) includes a physical communication interface. RAN 906 may include one or more base stations (such as base station 912 and base station 914) implementing connection 908 and connection 910.

[0104] In this example, Connection 908 and Connection 910 are air interfaces that enable this type of communication coupling and can conform to the RAT used by RAN906, such as LTE and / or NR, for example.

[0105] In some implementations, UE 902 and UE 904 can also exchange communication data directly via sidelink interface 916. UE 904 is shown configured to access an access point (shown as AP 918) via connection 920. By way of example, connection 920 may include a local wireless connection, such as a connection conforming to any IEEE 802.11 protocol, while AP 918 may include Wi-Fi. ® Router. In this example, AP 918 may connect to another network (e.g., the Internet) without using CN 924.

[0106] In the implementation, UE 902 and UE 904 may be configured to communicate with each other or with base station 912 and / or base station 914 on a multi-carrier communication channel using orthogonal frequency division multiplexing (OFDM) communication signals according to various communication technologies, such as, but not limited to, orthogonal frequency division multiple access (OFDMA) communication technology (e.g., for downlink communication) or single-carrier frequency division multiple access (SC-FDMA) communication technology (e.g., for uplink and ProSe or sidelink communication) , but the scope of the implementation is not limited in this respect. The OFDM signal may include multiple orthogonal subcarriers.

[0107] In some implementations, all or part of base station 912 or base station 914 may be implemented as one or more software entities running on a server computer as part of a virtual network. Furthermore, or in other implementations, base station 912 or base station 914 may be configured to communicate with each other via interface 922. In implementations where wireless communication system 900 is an LTE system (e.g., when CN 924 is an EPC), interface 922 may be an X2 interface. This X2 interface may be defined between two or more base stations (e.g., two or more eNBs, etc.) connected to the EPC and / or between two eNBs connected to the EPC. In implementations where wireless communication system 900 is an NR system (e.g., when CN 924 is a 5GC), interface 922 may be an Xn interface. This Xn interface is defined between two or more base stations (e.g., two or more gNBs, etc.) connected to the 5GC, between a base station 912 (e.g., a gNB) connected to the 5GC and an eNB, and / or between two eNBs connected to the 5GC (e.g., CN 924).

[0108] RAN 906 is shown communicatively coupled to CN 924. CN 924 may include one or more network elements 926 configured to provide various data and telecommunications services to customers / subscribers (e.g., users of UE 902 and UE 904) connected to CN 924 via RAN 906. Components of CN 924 may be implemented in a single physical device or a separate physical device, including components for reading and executing instructions from machine-readable or computer-readable media (e.g., non-transitory machine-readable storage media).

[0109] In the implementation scheme, CN 924 can be an EPC, and RAN 906 can be connected to CN 924 via S1 interface 928. In the implementation scheme, S1 interface 928 can be divided into two parts: an S1 user plane (S1-U) interface, which carries service data between base station 912 or base station 914 and the service gateway (S-GW); and an S1-MME interface, which is the signaling interface between base station 912 or base station 914 and the mobility management entity (MME).

[0110] In the implementation scheme, CN 924 can be a 5GC, and RAN 906 can be connected to CN 924 via NG interface 928. In the implementation scheme, NG interface 928 can be divided into two parts: an NG user plane (NG-U) interface, which carries service data between base station 912 or base station 914 and user plane function (UPF); and an S1 control plane (NG-C) interface, which is the signaling interface between base station 912 or base station 914 and access and mobility management function (AMF).

[0111] Generally, application server 930 can be an element that provides Internet Protocol (IP) bearer resources (e.g., packet-switched data services) for use with CN 924. Application server 930 can also be configured to support one or more communication services (e.g., VoIP sessions, group communication sessions, etc.) for UE 902 and UE 904 via CN 924. Application server 930 can communicate with CN 924 via IP communication interface 932.

[0112] Figure 10 A system 1000 for performing signaling 1032 between a wireless device 1002 and a network device 1018 according to an embodiment disclosed herein is illustrated. System 1000 may be part of a wireless communication system as described herein. Wireless device 1002 may be, for example, a UE in a wireless communication system. Network device 1018 may be, for example, a base station (e.g., an eNB or gNB) in a wireless communication system.

[0113] Wireless device 1002 may include one or more processors 1004. Processor 1004 is capable of executing instructions to perform various operations of wireless device 1002 as described herein. Processor 1004 may include one or more baseband processors, which are implemented using, for example, a central processing unit (CPU), digital signal processor (DSP), application-specific integrated circuit (ASIC), controller, field-programmable gate array (FPGA) device, another hardware device, firmware device, or any combination thereof configured to perform the operations described herein.

[0114] Wireless device 1002 may include memory 1006. Memory 1006 may be a non-transitory computer-readable storage medium that stores instructions 1008, which may include, for example, instructions executed by processor 1004. Instructions 1008 may also be referred to as program code or a computer program. Memory 1006 may also store data used by processor 1004 and results calculated by the processor.

[0115] Wireless device 1002 may include one or more transceivers 1010, which may include radio frequency (RF) transmitter circuitry and / or receiver circuitry that uses antenna 1012 of wireless device 1002 to facilitate signaling (e.g., signaling 1032) to and / or from wireless device 1002 and other devices (e.g., network device 1018) according to a corresponding RAT.

[0116] Wireless device 1002 may include one or more antennas 1012 (e.g., one, two, four, or more). In embodiments with multiple antennas 1012, wireless device 1002 may fully utilize the spatial diversity of these multiple antennas 1012 to transmit and / or receive multiple different data streams on the same time-frequency resource. This behavior may be referred to as, for example, multiple-input multiple-output (MIMO) behavior (referring to multiple antennas used at each of the transmitting and receiving devices to implement this aspect). MIMO transmission by wireless device 1002 may be implemented according to pre-decoding (or digital beamforming) applied to wireless device 1002, which multiplexes the data streams among antennas 1012 based on known or assumed channel characteristics, such that each data stream is received with appropriate signal strength relative to the other streams and at a desired location in the spatial domain (e.g., the location of the receiver associated with that data stream). Some implementations may use a single-user MIMO (SU-MIMO) approach (where all data streams are directed to a single receiver) and / or a multi-user MIMO (MU-MIMO) approach (where individual data streams may be directed to individual (different) receivers at different locations in the airspace).

[0117] In some implementations with multiple antennas, wireless device 1002 may implement analog beamforming technology, whereby the phase of the signal transmitted by antenna 1012 is relatively adjusted so that the (joint) transmission of antenna 1012 can be directed (this is sometimes referred to as beam control).

[0118] Wireless device 1002 may include one or more interfaces 1014. Interface 1014 can be used to provide input to or output to wireless device 1002. For example, wireless device 1002 (UE) may include interface 1014, such as a microphone, speaker, touchscreen, and buttons, to allow a user of the UE to make inputs and / or outputs to the UE. Other interfaces of such UEs may consist of transmitters, receivers, and other circuitry that allow communication between the UE and other devices (e.g., in addition to the transceiver 1010 / antenna 1012 described), and may be configured according to known protocols (e.g., Wi-Fi). ® ,Bluetooth ® (etc.) to perform the operation.

[0119] Wireless device 1002 may include a RACH trigger module 1016. The RACH trigger module 1016 may be implemented via hardware, software, or a combination thereof. For example, the RACH trigger module 1016 may be implemented as a processor, circuitry, and / or instructions 1008 stored in memory 1006 and executed by processor 1004. In some examples, the RACH trigger module 1016 may be integrated within processor 1004 and / or transceiver 1010. For example, the RACH trigger module 1016 may be implemented via a combination of software components (e.g., executed by a DSP or general-purpose processor) and hardware components (e.g., logic gates and circuitry) within processor 1004 or transceiver 1010.

[0120] The RACH trigger module 1016 can be used in various aspects of this disclosure, such as Figure 6 , Figure 7 and / or Figure 8 Regarding the aspect, the RACH triggering module 1016 can configure the wireless device 1002 to: trigger a second RACH process for UL synchronization on the SCC in response to a failure of the first RACH process for UL synchronization on the SCC and a measurement report reporting an RSRP of the SCC; trigger a second RACH process for UL synchronization on the SCC in response to a failure of the first RACH process for UL synchronization on the SCC and a CSI report reporting a first CSI component of the SCC above a threshold; and / or trigger a second RACH process for UL synchronization on the SCC in response to a failure of the first RACH process for UL synchronization on the SCC and a DL throughput through the SCC improved in the first time period.

[0121] Network device 1018 may include one or more processors 1020. Processor 1020 is executable instructions to perform various operations of network device 1018 as described herein. Processor 1020 may include one or more baseband processors, which are implemented using, for example, a CPU, DSP, ASIC, controller, FPGA device, another hardware device, firmware device, or any combination thereof configured to perform the operations described herein.

[0122] Network device 1018 may include memory 1022. Memory 1022 may be a non-transitory computer-readable storage medium that stores instructions 1024, which may include, for example, instructions executed by processor 1020. Instructions 1024 may also be referred to as program code or a computer program. Memory 1022 may also store data used by processor 1020 and results calculated by the processor.

[0123] Network device 1018 may include one or more transceivers 1026, which may include RF transmitter circuitry and / or receiver circuitry that uses the antenna 1028 of network device 1018 to facilitate signaling (e.g., signaling 1032) to and / or from network device 1018 and other devices (e.g., wireless device 1002) according to the corresponding RAT.

[0124] Network device 1018 may include one or more antennas 1028 (e.g., one, two, four or more). In embodiments having multiple antennas 1028, network device 1018 may perform MIMO, digital beamforming, analog beamforming, beam control, etc., as described.

[0125] Network device 1018 may include one or more interfaces 1030. Interface 1030 can be used to provide input to or output to network device 1018. For example, network device 1018 as a base station may include interface 1030 consisting of transmitters, receivers and other circuitry (e.g., in addition to the transceiver 1026 / antenna 1028 already described), which enable the base station to communicate with other equipment in the core network and / or enable the base station to communicate with external networks, computers and databases, etc., for the purpose of operating, managing and maintaining the base station or other equipment operably connected to the base station.

[0126] The embodiments contemplated herein include an apparatus comprising components for performing one or more elements of any of the methods 600, 700, and / or 800. The apparatus may be, for example, a UE (such as wireless device 1002 (UE), as described herein).

[0127] The embodiments contemplated herein include one or more non-transitory computer-readable media comprising instructions that, when executed by one or more processors of an electronic device, cause the electronic device to perform one or more elements of any of the methods of method 600, method 700, and / or method 800. The non-transitory computer-readable medium may be, for example, the memory of a UE (such as memory 1006 of wireless device 1002 (UE), as described herein).

[0128] The embodiments contemplated herein include an apparatus comprising logic components, modules, or circuitry for performing one or more elements of any of the methods 600, 700, and / or 800. The apparatus may be, for example, a UE (such as wireless device 1002 (UE), as described herein).

[0129] The embodiments contemplated herein include an apparatus comprising: one or more processors and one or more computer-readable media including instructions that, when executed by the one or more processors, cause the one or more processors to perform one or more elements of any of method 600, method 700, and / or method 800. The apparatus may be, for example, a UE (such as wireless device 1002 (UE), as described herein).

[0130] The implementation scheme envisioned herein includes a signal as described in or associated with one or more elements of any of the methods 600, 700, and / or 800.

[0131] The embodiments contemplated herein include a computer program or computer program product comprising instructions, wherein execution of the program by a processor will cause the processor to perform one or more elements of any of method 600, method 700, and / or method 800. The processor may be a processor of the UE (such as processor 1004 of wireless device 1002 (UE), as described herein). These instructions may, for example, be located in the processor and / or in the memory of the UE (such as memory 1006 of wireless device 1002 (UE), as described herein).

[0132] For one or more embodiments, at least one of the components set forth in one or more of the foregoing figures may be configured to perform one or more operations, techniques, processes, and / or methods as described herein. For example, a baseband processor as described herein in conjunction with one or more of the foregoing figures may be configured to operate according to one or more of the examples set forth herein. Similarly, circuitry associated with a UE, base station, network element, etc., as described above in conjunction with one or more of the foregoing figures may be configured to operate according to one or more of the examples set forth herein.

[0133] Unless otherwise expressly stated, any of the above embodiments may be combined with any other embodiment (or combination of embodiments). The foregoing description of one or more specific embodiments provides illustration and description, but is not intended to be exhaustive or to limit the scope of the embodiments to the precise form disclosed. In view of the teachings above, modifications and variations are possible, or modifications and variations may be derived from practice of various embodiments.

[0134] Implementations and specific embodiments of the systems and methods described herein may include various operations embodied in machine-executable instructions to be executed by a computer system. The computer system may include one or more general-purpose or special-purpose computers (or other electronic devices). The computer system may include hardware components, including specific logical parts for performing the operations; or may include a combination of hardware, software, and / or firmware.

[0135] It should be recognized that the systems described herein include descriptions of specific implementations. These implementations may be combined into a single system, partially integrated into other systems, divided into multiple systems, or otherwise partitioned or combined. Furthermore, it is contemplated that parameters, attributes, aspects, etc., of one implementation may be used in one implementation. For clarity, these parameters, attributes, aspects, etc., are described only in one or more implementations, and it should be recognized that, unless expressly stated herein, these parameters, attributes, aspects, etc., may be combined with or substituted for parameters, attributes, aspects, etc., of another implementation.

[0136] As is widely recognized, the use of personally identifiable information should comply with privacy policies and practices that are generally accepted to meet or exceed industry or governmental requirements for protecting user privacy. Specifically, personally identifiable information data should be managed and processed to minimize the risk of unintentional or unauthorized access or use, and the nature of authorized use should be clearly explained to users.

[0137] Although the foregoing has been described in considerable detail for clarity, it will be apparent that certain changes and modifications can be made without departing from the principles of the invention. It should be noted that many alternative ways exist to implement both the processes and apparatus described herein. Therefore, embodiments of the invention should be considered illustrative rather than restrictive, and this specification is not limited to the details given herein, but can be modified within the scope and equivalents of the appended claims.

Claims

1. A method for a user equipment (UE) wherein the UE is in a radio resource control (RRC) connection mode with the network via a primary component carrier (PCC) of a first timing advance group (TAG), the method comprising: The first failure of the first random access channel (RACH) procedure for uplink (UL) synchronization of the secondary component carrier (SCC) configured for the UE for the second TAG of the network; The first measurement report generated by the UE for the network reports the first reference signal received power (RSRP) of the SCC. as well as In response to a first failure of the first RACH process for UL synchronization of the SCC and a first measurement report indicating that the SCC reported the first RSRP, a second RACH process for UL synchronization of the SCC is triggered on the SCC.

2. The method according to claim 1, further comprising: Identify a second failure of the second RACH process for the UL synchronization of the SCC; The second measurement report generated by the UE for the network indicates that the second RSRP of the SCC was reported; as well as In response to a second failure of the second RACH process for UL synchronization of the SCC and a second measurement report indicating that the second RSRP of the SCC was reported, a third RACH process for UL synchronization of the SCC is triggered on the SCC.

3. An apparatus for a user equipment (UE), the apparatus comprising: Baseband processor; and A memory storing instructions, which, when executed by the baseband processor, configure the device to: when the UE is in Radio Resource Control (RRC) connection mode with the network via the primary component carrier (PCC) of the network's first timing advance group (TAG): The first failure of the first random access channel (RACH) procedure for uplink (UL) synchronization of the secondary component carrier (SCC) configured for the UE for the second TAG of the network; The first channel state information (CSI) report generated by the UE for the network reports a first CSI component that satisfies the threshold for the SCC; as well as In response to a first failure of the first RACH process for UL synchronization of the SCC and a first CSI report indicating that the SCC has a first CSI component above the threshold, a second RACH process for UL synchronization of the SCC is triggered on the SCC.

4. The apparatus of claim 3, wherein the first CSI component includes a channel quality index (CQI), the threshold includes a CQI threshold, and the second RACH procedure is triggered in response to determining that the CQI satisfies the CQI threshold.

5. The apparatus of claim 3, wherein the first CSI component includes a predecoder matrix indicator (PMI), the threshold includes a PMI threshold, and the second RACH process is triggered in response to determining that the PMI satisfies the PMI threshold.

6. The apparatus of claim 3, wherein the first CSI component includes a rank indicator (RI), the threshold includes an RI threshold, and the second RACH process is triggered in response to determining that the RI satisfies the RI threshold.

7. The apparatus of claim 3, wherein the instructions, when executed by the baseband processor, further configure the apparatus to: when the UE is in the RRC connection mode with the network via the first PCC of the first TAG of the network: Identify a second failure of the second RACH process for the UL synchronization of the SCC; The second CSI report generated by the UE for the network reports a second CSI component that satisfies the threshold for the SCC; as well as In response to a second failure of the second RACH process for UL synchronization of the SCC and a second CSI report indicating that the second CSI component for the SCC is above the threshold, a third RACH process for UL synchronization of the SCC is triggered on the SCC.

8. A non-transitory computer-readable storage medium comprising instructions that, when executed by one or more processors of a user equipment (UE) in a radio resource control (RRC) connection mode with the network via a primary component carrier (PCC) of a first timing advance group (TAG), cause the UE to: The first failure of the first random access channel (RACH) procedure for uplink (UL) synchronization of the secondary component carrier (SCC) configured for the UE for the second TAG of the network; The downlink (DL) throughput through the SCC has improved in the first time period; as well as In response to a first failure of the first RACH process for the UL synchronization of the SCC and an indication that the DL throughput through the SCC has improved during the first time period, a second RACH process for the UL synchronization of the SCC is triggered on the SCC.

9. The non-transitory computer-readable storage medium of claim 8, wherein the UE identifies that the DL throughput through the SCC has improved during the first time period by: Determine the percentage improvement in DL throughput through the SCC during the first time period; and The percentage improvement in DL throughput is determined to meet the threshold for percentage improvement in DL throughput.

10. The non-transitory computer-readable storage medium of claim 8, wherein the first time period begins from the first RACH process.

11. The method according to the non-transitory computer-readable storage medium 8, wherein the instructions, when executed by the one or more processors of the UE, further cause the UE to: Identify a second failure of the second RACH process for the UL synchronization of the SCC; The DL throughput via the SCC has improved in the second time period; and In response to a second failure of the second RACH process for the UL synchronization of the SCC and an indication that the DL throughput through the SCC has improved during the second time period, a third RACH process for the UL synchronization of the SCC is triggered on the SCC.

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