Radio link maintenance involving multiple uplink carriers

Abstract

The invention relates to a method in a user equipment (UE) (200) for handling radio link failure, wherein the UE is connected to a radio communications network by means of a plurality of uplink, UL, carriers (220, 230), the method comprising: monitoring (S41) retransmissions of radio link control, RLC, data packets for at least two of the plurality of UL carriers; determining (S42) a failure of RLC data packet transmission with respect to one of the UL carriers; and providing (S43) information indicating the failure and the UL carrier; the invention also relates to a method in a UE (200) for handling radio link failure, wherein the UE is connected to a radio communications network by means of a plurality of UL carriers (210, 220, 230), the method comprising: performing (S61) retransmissions of a certain RLC data packet on at least two of the plurality of UL carriers; monitoring (S62) retransmissions of radio link control, RLC, data packets jointly for the at least two UL carriers; and providing (S63) information indicating a joint RLF; the invention also relates to a corresponding method in a base station (100), a corresponding UE (200) and base station (100), a corresponding communications system and a corresponding method in a communications system.

Description

Technical Field

[0001] This invention relates to the detection and handling of radio link failures. It also relates to the detection and handling of radio link failures in carrier configurations involving multiple uplink UL carriers (particularly a primary UL carrier and a secondary UL carrier). Background Technology

[0002] Auxiliary uplink (SUL) carriers can be introduced into 5G / NR compliant networks to improve uplink coverage.

[0003] Because relatively low carrier bands have already been deployed using 2G, 3G, and 4G wireless communication systems, NR will be deployed at relatively high frequencies. For wireless communication, propagation loss is roughly proportional to the square of the carrier frequency. Therefore, coverage issues may exist for wireless communication at high carrier frequencies. For the downlink, network access nodes or NR base stations (gNBs) can be equipped with powerful antenna systems and amplifiers to increase transmit power density, thereby improving DL coverage. However, for UL (i.e., for the UE side), there are several limitations, such as transmit power, antenna size, and cost. Therefore, at high frequencies, a mismatch may exist between UL and DL for NR cells.

[0004] Given these potential issues, an auxiliary uplink (SUL) carrier can be provided for NR cells, giving NR cells both an SUL carrier and an NR UL carrier. The SUL carrier can be a relatively low-frequency carrier that can be shared with other RAT systems such as LTE (in the time and / or frequency domains).

[0005] When the radio condition of the NR UL carrier is poor, the SUL carrier can be used. When the radio condition of the NR UL carrier becomes good enough, the SUL carrier can be switched off again. Because radio conditions can change relatively quickly over time, this carrier switching can be triggered frequently.

[0006] LTE provides the Radio Link Layer (RLF) procedure in LTE to assist the UE in performing fast and reliable recovery without going through RRC_IDLE. This fast and reliable recovery may help avoid unnecessary latency caused by RACH access in RRC_IDLE.

[0007] Figure 2The diagram illustrates radio link monitoring in LTE (corresponding to Figure 22.8 in the 2nd edition of *LTE – The UMTS Long Term Evolution From Theory to Practice* by Stefania Sesia, Issam Toufik, and Matthew Baker). In LTE, several factors can lead to radio link failures:

[0008] 1. Timer T310 expired;

[0009] 2. To reach the maximum number of RLC retransmissions in the uplink; and

[0010] 3. Switching between faults and timer T304 expiration

[0011] Regarding the expiration of timer T310, while the UE is in RRC connection mode, the UE monitors the downlink radio channel quality based on the downlink reference symbol. The UE compares the measured downlink channel quality with certain thresholds: Q... out Used for asynchronous events, and Q in Used for synchronization events. The physical channel assesses downlink channel quality and can periodically send indications of desynchronization or synchronization to Layer 3. The UE Layer 3 can then assess radio link failures based on the synchronization and desynchronization indications (e.g., by applying Layer 3 filters). Timer T310 is started when continuously received desynchronization indications exceed counter N310. While T310 is running, if the UE continuously receives synchronization indications N311 from the physical layer, the radio link is considered to have been restored.

[0012] When timer T310 expires, the UE declares or triggers a radio link failure.

[0013] During the handover process, when the UE receives a handover command from the source cell, timer T304 is started. The value of timer T304 should be set to allow the UE to attempt the maximum RACH access to the target cell. When timer T304 expires, a radio link failure due to the handover is detected.

[0014] When a radio link failure is triggered, radio connection re-establishment is initiated. The UE should first perform a cell search to determine the optimal cell for radio link re-establishment. According to 3GPP TS 36.300 (current version 15.3.0), the UE can select a ready cell, a different cell from the same eNB, or a ready cell from a different eNB. Since the previous UE context can be established through inter-cell communication, activity can be restarted via the radio connection re-establishment process (i.e., the UE remains in connected mode). However, when a ready cell is unavailable, the UE can select an unready cell. In this case, the UE must enter idle mode and subsequently attempt to establish a radio connection. In this situation, the UE's activity cannot be restarted. Figure 3 Table 10.1.6-1 from 3GPP document TS 36.300 is shown, which guides UE behavior for target cell selection in relation to mobility and radio link failure.

[0015] For NR cells configured with SUL carriers, there is at least one SUL carrier and one NR UL carrier in a single cell. Existing RLF triggering mechanisms may be insufficient for SUL cases because the UE supports two ULs in the same cell.

[0016] From a frequency band combination perspective, a SUL carrier may not be paired with any downlink frequency. Instead, an SUL carrier and an NR UL carrier together can be associated with a downlink NR carrier. From a technical potential perspective, there are two options for modeling the SUL carrier. In the first option, the SUL carrier is modeled as a separate uplink carrier, distinct from the NR UL carrier. The aggregation of the two carriers is the same as uplink carrier aggregation. Therefore, the SUL carrier forms a separate Scell ​​(secondary cell). In the second option, the SUL carrier and the NR UL / DL carrier are in the same cell. The SUL carrier is more like a separate UL configuration. The UE can maintain two UL configurations, while the UE can also periodically maintain only one UL configuration active. Summary of the Invention

[0017] Therefore, there is a need for technologies that allow for the efficient use of time and resources to determine accurate TA information.

[0018] In one aspect, a method for handling radio link failures in a user equipment (UE) is provided, wherein the UE is connected to a radio communication network by means of a plurality of uplink UL carriers, the method comprising:

[0019] -Retransmission of monitoring radio link control (RLC) data packets for each of the multiple UL carriers;

[0020] - Determine a fault in the RLC data packet transmission of one of the UL carriers; and

[0021] - Provides information indicating the fault of the UL carrier.

[0022] On the other hand, a method for handling radio link failures in a user equipment (UE) is provided, wherein the UE is connected to a radio communication network by means of multiple uplink UL carriers, the method comprising:

[0023] - Perform retransmission of an RLC data packet on at least two of the plurality of UL carriers;

[0024] - For retransmission of radio link control (RLC) data packets jointly monitored by two UL carriers; and

[0025] - Provides information indicating common RLF.

[0026] On the other hand, a user equipment (UE) for handling radio link failures is provided, wherein the UE is adapted to perform the above-described method.

[0027] On the other hand, a method for handling radio link failures in a base station gNB of a radio communication network is provided, the method comprising: receiving information about a failure in the transmission of RLC data packets in one of the UL carriers, wherein the failure has been individually determined by monitoring the retransmission of radio link control RLC data packets individually for at least two of the plurality of UL carriers.

[0028] On the other hand, a method in a gNB is provided, comprising: receiving information from a UE indicating a common RLF, wherein the common RLF originates from performing a retransmission of an RLC data packet at the UE for jointly monitoring at least two of a plurality of UL carriers on two UL carriers.

[0029] On the other hand, a base station gNB is provided for handling radio link failures, wherein the gNB is adapted to perform the aforementioned methods.

[0030] On the other hand, a communication system is provided, including a host computer comprising: processing circuitry configured to provide user data; and a communication interface configured to forward the user data to a cellular network for transmission to a user equipment (UE), wherein the cellular network includes a base station (gNB) having a radio interface and processing circuitry, the processing circuitry of the base station being configured to perform at least one of the following:

[0031] - Receive information about a fault in the transmission of RLC data packets on one of the UL carriers, wherein the fault has been determined at the UE by monitoring the retransmission of RLC data packets via radio link control for each of at least two of the plurality of UL carriers; and

[0032] - Receive information indicating a common RLF, where the common RLF originates from the retransmission of an RLC data packet performed at the UE for joint monitoring of at least two of the multiple UL carriers on two UL carriers.

[0033] On the other hand, a method for implementation in a communication system is provided, the method comprising:

[0034] - Provide user data at the host computer; and

[0035] - At the host computer, a transmission carrying user data is initiated to the UE via a cellular network including a base station, wherein the base station performs at least one of the following:

[0036] - Receive (S51) information regarding a fault in the transmission of RLC data packets in one of the UL carriers, wherein the fault has been determined at the UE by monitoring the retransmission of RLC data packets via radio link control for each of at least two of the plurality of UL carriers, and

[0037] - Receive (S71) information indicating a common RLF, wherein the common RLF originates from the retransmission of an RLC data packet performed at the UE for joint monitoring of at least two of the multiple UL carriers on two UL carriers. Attached Figure Description

[0038] The present disclosure will be described in more detail below with reference to exemplary embodiments illustrated in the accompanying drawings, in which:

[0039] Figure 1 The diagram schematically illustrates a radio communication network including a base station and a UE.

[0040] Figure 2 The diagram illustrates a timeline including radio link monitoring in LTE;

[0041] Figure 3 This is a schematic table from the 3GPP specification, which illustrates different UE behaviors for target cell selection in relation to mobility and radio link failures.

[0042] Figure 4 Exemplary method steps performed in a UE with respect to a first embodiment are schematically illustrated;

[0043] Figure 5 The illustration shows the situation based on Figure 4 Exemplary method steps performed in a base station;

[0044] Figure 6 Exemplary method steps performed in a UE with respect to the second embodiment are schematically illustrated;

[0045] Figure 7 Exemplary method steps performed in a base station according to a second embodiment are schematically illustrated;

[0046] Figure 8 The schematic diagram illustrates the method used to implement according to Figure 4 or Figure 6 The method of UE;

[0047] Figure 9 The schematic diagram illustrates the method used to implement according to Figure 5 or Figure 7 Base station of the method;

[0048] Figure 10 The diagram schematically illustrates a telecommunications network connected to a host computer via an intermediate network;

[0049] Figure 11 This is a generalized block diagram of a host computer communicating with user equipment via a base station through a partially wireless connection; and

[0050] Figures 12 to 15 This is a flowchart illustrating a method implemented in a communication system that includes a host computer, a base station, and user equipment. Detailed Implementation

[0051] Figure 1 The illustration depicts a wireless communication network 10 based on the NR standard currently being developed by the 3rd Generation Partnership Project (3GPP). The wireless communication network 10 includes one or more base stations 100 that provide services to user equipment (UE) 200 in a cell 20 of the wireless communication network 10. In the 3GPP standard, the base stations 100 in the wireless communication network 10 are also referred to as evolved NodeBs (eNBs) and gNodeBs (gNBs). Although in... Figure 1 Only one cell 20 and one base station 100 are shown, but those skilled in the art will understand that a typical wireless communication network 10 includes many cells 20 served by many base stations 100. UE 200 may include cellular phones, smartphones, laptops, notebook computers, tablets, machine-to-machine (M2M) devices (also known as machine-type communication (MTC) devices), or other types of wireless end-user devices capable of communicating via wireless communication network 10.

[0052] Figure 1The illustration also shows cell 20, with NR downlink carrier 210, primary carrier or NR UL carrier 220, and secondary uplink (SUL) carrier 230 each having different coverage ranges, so that the NR cell has SUL carriers and NR UL carriers in the uplink. The SUL carrier can be a relatively low frequency carrier that can be shared with other RAT systems such as LTE (in the time domain and / or frequency domain). Figure 1 Exemplary depictions are provided of different coverages of NR UL carriers, SUL carriers, and NR DL carriers associated with NR cells, wherein NR UL carriers and SUL carriers can be paired to obtain NR frequency combinations.

[0053] When UE 200 loses synchronization with the network, it can declare or trigger a Radio Link Failure (RLF). As a result, the UE can release network resources, and any ongoing services will be interrupted.

[0054] In the Figure 4 In the illustrated embodiment, UE 200 performs the following steps:

[0055] S41: Monitor RLC retransmissions individually for multiple carriers (e.g., primary carrier and secondary carrier);

[0056] S42: Determine a fault (RLF) in the RLC data packet transmission of one of the UL carriers; and

[0057] S43: Provides information indicating a fault and the UL carrier.

[0058] Individual monitoring can mean monitoring for fault events or retransmissions for each of multiple carriers; for example, using a separate RLF counter, and / or counting retransmissions separately for each of multiple carriers. Individual monitoring can also include determining, for each carrier, the number of retransmissions reached or passed individually. Some thresholds may differ for each carrier.

[0059] The base station gNB can perform the following corresponding steps, such as Figure 5 As shown in the diagram:

[0060] S51: Receive information about a fault in the transmission of RLC data packets in one of the UL carriers.

[0061] The fault was identified by the UE through individual monitoring of retransmissions of Radio Link Control (RLC) data packets for at least two of the multiple UL carriers.

[0062] In this embodiment, the primary carrier is an NR UL carrier, and the secondary carrier is an auxiliary UL SUL carrier.

[0063] If an RLC transmission failure is detected on one of multiple carriers, an indication of the RLC transmission failure and the carrier on which the transmission failure has occurred is generated. In a separate step (at the RRC layer), the UE can determine the corresponding carrier RLF, for example, NR RLF and / or SUL RLF.

[0064] In this embodiment, UE 200 may include functions categorized according to different layers. UE 200 may include an RLC entity for performing RLC functions and an RRC entity for performing RRC functions.

[0065] The RLC entity monitors RLC retransmission failures individually for multiple carriers (e.g., primary carrier and secondary carrier).

[0066] If a transmission fault is detected on one of multiple carriers, the RLC entity provides the RRC entity with an indication of the RLC transmission fault and the carrier on which the transmission fault has occurred. The RRC entity then determines the RLF for the corresponding carrier.

[0067] In an embodiment, if a given maximum number of RLC retransmissions of RLC data packets (RLC AM PDUs) has been reached (or exceeded) for a carrier (e.g., a primary carrier or a secondary carrier), an RLC transmission failure for such a carrier is assumed. Therefore, the RLC entity can send a report to the RRC layer indicating the RLC transmission failure and the corresponding carrier.

[0068] The maximum number can be similar for different carriers, or for example, different for NR UL carriers and SUL carriers.

[0069] In an embodiment, the network (e.g., gNB) can configure different RLC configurations for different carriers (e.g., SUL carriers and NR carriers). Furthermore, different maximum numbers of RLC retransmissions can be configured for SUL carriers and NR carriers to trigger RLF failures.

[0070] In this embodiment, it is assumed that the NR UL carrier can be deployed at a higher carrier frequency than the SUL carrier. This means that the NR UL carrier can be associated with a higher subcarrier spacing (i.e., a shorter slot duration), allowing for a higher maximum number of RLC retransmissions to be configured for the NR UL carrier, while a lower maximum number of RLC retransmissions can be configured for the SUL carrier. This avoids unnecessary RLF events.

[0071] In this embodiment, a common RLC configuration for both the SUL and NR carriers and a common counter for RLC retransmissions on both carriers are provided. For the same RLC data packet (RLC AM PDU), it is possible that a portion of the RLC retransmission is carried on the NR UL carrier, while the remainder is carried on the SUL carrier. In this case, when the maximum number of RLC retransmissions for the RLC AM PDU has been reached, the RLC entity can send a report to the RRC layer indicating that the maximum RLC retransmission has been reached, without sending any carrier indicator.

[0072] Figure 6 The illustration shows an exemplary step performed by UE 200:

[0073] S61: Perform retransmission of an RLC data packet on at least two of a plurality of UL carriers;

[0074] S62: For retransmission of Radio Link Control (RLC) data packets jointly monitored by two UL carriers; and

[0075] S63: Provides information indicating common RLF.

[0076] Joint monitoring can mean monitoring for fault events or retransmissions together across multiple carriers; for example, using a single RLF counter for all carriers, and / or counting faults together across all of multiple carriers. Joint monitoring can also include determining a certain threshold number of retransmissions reached or passed across all carriers together.

[0077] Figure 7 The following are corresponding exemplary steps performed in base station gNB 100:

[0078] S71: Receive information from UE 200 indicating a common RLF, wherein the common RLF originates from the retransmission of an RLC data packet performed at UE 200 for joint monitoring of at least two of a plurality of UL carriers on two UL carriers.

[0079] In this embodiment, the gNB can configure how the UE counts RLC retransmissions on different carriers.

[0080] In one option, the UE can be configured such that the UE RLC counts RLC retransmissions only on a specific carrier (e.g., an NR UL carrier or a SUL carrier) in order to report RLC transmission failures.

[0081] In another option, the UE can be configured to have the UE RLC count RLC retransmissions on all carriers in order to report RLC transmission failures.

[0082] In this embodiment, if an NR-RLF is triggered, or if a Report Indication (RLC) data transmission failure is sent by the RLC entity (indicating that RLC data has indeed passed on the NR carrier), the UE may take one of the following actions:

[0083] If the SUL carrier is configured and active, the UE triggers a Schedule Request (SR) transmission on the SUL carrier, instructing the UE to switch to the SUL carrier for UL data transfer. This action can only be performed if the DL channel quality (such as RSRP) is below a given threshold.

[0084] If the SUL carrier is deactivated, or if there is no PUCCH-SR resource available on it for the corresponding logical channel LCH, the UE can trigger access to the random access channel RACH (i.e., the shared channel used by the radio terminal to access the mobile network) on the SUL carrier, thereby indicating that data (RLC) transmission has not passed on the NR carrier.

[0085] In response to receiving an indication of an RLF failure on a carrier (e.g., an NR UL carrier), the network (gNB) can take appropriate action. In an embodiment, the gNB may command the UE to switch to another carrier (e.g., a SUL carrier) for PUSCH transmission.

[0086] Accordingly, PUCCH-SR resources can be configured for the corresponding LCH.

[0087] The gNB can further configure an existing SUL carrier to be active, or if the existing SUL is inactive, it can reconfigure the UE with another active SUL carrier.

[0088] In another option, the UE (e.g., the UE Media Access MAC entity) can signal to the network (gNB) that data (RLC) transmission is stuck on the NR carrier. Signaling is then performed using RRC, MAC CE, and / or any other Layer 1 / Layer 2 signaling means.

[0089] In this embodiment, if a SUL-RLF is triggered, or a report is received from the RLC entity indicating that the indication (RLC) data transmission did not pass on the SUL carrier, the UE may take one of the following actions to recover from the fault:

[0090] The UE should first perform a cell search to determine the best cell for radio link re-establishment. The UE can select a ready cell, which can be the same cell, a different cell from the same gNB, or a ready cell from a different gNB, where activity can be restarted via the radio connection re-establishment process (the UE remains in connected mode) because the previous UE context can be achieved through inter-cell communication.

[0091] The UE can determine the optimal cell based on network configuration. Specifically, the UE can be configured as follows:

[0092] - Select only cells that support SUL carriers;

[0093] - Cell selection is based on measurements of both DL and UL radio link quality. For each cell, the UE can estimate the UL radio link quality of each carrier belonging to the same cell (e.g., considering carrier frequency), either by collecting measurements provided by the network or by utilizing previously acquired (historical) measurement data. In one example of this, assume two candidate cells are available to the UE, where cell 1 is configured with both SUL and NR UL carriers, and cell 2 is not configured with an SUL carrier in the UL. Although cell 2 has better DL radio link quality, the UE can select cell 1. This selection can be performed when the DL radio link quality of both cells is above a certain minimum quality threshold and / or the SUL carrier provides a greater path gain than the NR UL carrier. This selection can be advantageous considering that UL measurements are more important for cell selection than DL measurements (as a specific example, the configurable DL RSRP threshold for candidate cell selection could be -90 dBm). As an example, for cell 1, the DL RSRP is measured at -85 dBm. Further exemplarily, the SUL carrier can provide a path gain of approximately 7 dB greater than the NR UL carrier. As an example, the DL RSRP is measured at approximately -82 dBm in cell 2. In this case, the UE should select cell 1 because the uplink radio quality of cell 1 is 4 dB better than that of cell 2.

[0094] - Select the optimal cell solely based on DL radio channel quality measurements; and / or

[0095] -Consider the load measurement of the cell and the load of each carrier belonging to the same cell.

[0096] In an embodiment, if an RLC retransmission failure is triggered on a specific UL carrier, or on all UL carriers belonging to the same cell (e.g., if an RLC retransmission for an RLC AM PDU reaches a configured threshold), the network can configure the UE. When an RLC failure is triggered, the same or similar recovery actions described above can be applied.

[0097] In this embodiment, when an RLF is triggered, if no ready cell is available for radio connection re-establishment, the UE leaves the RRC connected state and enters the RRC idle state. The UE can then select the best unavailable cell. The selection of the best cell can be performed as described above.

[0098] In an embodiment, when the random access (RA) procedure for radio connection reconstruction for a UE is determined to be an NR cell with a SUL carrier, the network can configure one of the following rules or policies for such a procedure:

[0099] - The UE should always select the SUL carrier for RACH access in the target cell.

[0100] - If the corresponding PRACH resource is on a SUL carrier or an NR UL carrier, the UE should independently select the nearest PRACH transmission opportunity.

[0101] - The UE should still select the UL carrier for RACH access based on the existing policy. For example, if the DL RSRP is higher than a certain (pre-configured) threshold, the UE can select the NR UL carrier; otherwise, the UE selects the SUL carrier.

[0102] - The UE can initiate RACH access in parallel on two carriers, ensuring that RACH access on at least one carrier can be acknowledged. When one carrier is acknowledged, RACH access on the other carrier may be stopped.

[0103] The configuration for radio link maintenance at the RLF can be configured via UE-specific RRC signaling or broadcast SIB.

[0104] In the following text, the above embodiments are enhanced to include additional features:

[0105] In the first embodiment, the UE RLC entity should report which of the SUL carriers and NR UL carriers has reached the maximum RLC retransmission attempt.

[0106] ● If the maximum number of RLC retransmissions of the RLC AM PDU has been reached in the NR UL carrier, the RLC entity sends a report to the RRC including RLC transmission failure information and UL carrier indicator, and the RRC can determine the NR-RLF.

[0107] ● If the maximum number of RLC retransmissions of the RLC AM PDU has been reached in the SUL carrier, the RLC entity sends a report including RLC transmission failure information and UL carrier indicator. The RLC entity sends a report to the RRC, and the RRC can determine the SUL-RLF.

[0108] In the second embodiment, the base station (gNB) can configure different RLC configurations for the SUL carrier and the NR carrier, wherein different maximum numbers of RLC retransmissions for triggering RLF faults can be configured for the SUL carrier and the NR carrier. It can be assumed that the NR UL carrier is deployed at a higher carrier frequency than the SUL carrier, meaning that the NR UL carrier can be associated with a higher subcarrier spacing (i.e., a shorter slot duration); thus, a higher maximum number of RLC retransmissions can be configured for the NR UL carrier, while a lower maximum number of RLC retransmissions can be configured for the SUL carrier. In this way, unwanted RLF events can be avoided.

[0109] In the third embodiment, it can be assumed that there is only one RLC configuration for both the SUL and NR carriers. There may be a common counter for RLC retransmissions on both carriers. For the same RLC AM PDU, it is possible that a portion of the RLC retransmissions is carried on the NR UL carrier, while the remainder is carried on the SUL carrier. In this case, when the maximum number of RLC retransmissions for the RLC AM PDU has been reached, the RLC entity sends a report to the RRC indicating that the maximum RLC retransmission has been reached; the carrier indicator may not be present in the report.

[0110] In the fourth embodiment, the base station (gNB) can configure the UE to determine on which carriers to count RLC retransmissions. In one option, the UE RLC can count RLC retransmissions only on a specific carrier triggered by the RLF. In another option, the UE RLC can count RLC retransmissions on all carriers triggered by the RLF.

[0111] As an additional consideration, if the RLC entity may need to know on which carrier each PUSCH transmission is carried, this knowledge can be communicated to higher layers by the physical PHY layer.

[0112] The following examples involve different options for UE actions when an RLF event is detected, which are described in the section above (Radio Connection Maintenance).

[0113] Furthermore, in the fifth embodiment, if an NR RLF is triggered, or if the RLC entity sends a report indicating that RLC data transmission has not passed on the NR carrier, the UE may take one or more of the following actions:

[0114] ● If the SUL carrier is configured and active, and there is a PUCCH-SR resource configured for the corresponding LCH in the SUL carrier, the UE MAC triggers SR transmission on the SUL carrier, thereby instructing the UE to switch to the SUL carrier for UL data transfer. This action may only apply if the DL channel quality (such as RSRP) is below a given threshold.

[0115] ● If the SUL carrier is deactivated, or if there are no PUCCH-SR resources available for the corresponding LCH on it, the UEMAC triggers RACH access on the SUL carrier, indicating that data (RLC) transmission has not passed on the NR carrier. The gNB can take appropriate action; for example, the gNB can command the UE to switch to the SUL carrier for PUSCH transmission. Accordingly, PUCCH-SR resources can be configured for the corresponding LCH. The gNB can configure an existing SUL carrier to be active, or if the existing SUL is inactive, reconfigure the UE with another active SUL carrier.

[0116] ●Optionally, the UE MAC can signal to the gNB that data (RLC) transmission is blocked on the NR carrier. Signaling options may include RRC, MAC CE, or other L1 / L2 signaling means.

[0117] In the sixth embodiment, if a SUL-RLF is triggered, or a report is received from the RLC entity indicating that the indication (RLC) data transmission did not pass on the SUL carrier, the UE may take one or more of the following actions to recover from the fault:

[0118] ●The UE should first perform a cell search to determine the best cell for radio link re-establishment. The UE can select a ready cell, which can be the same cell, a different cell from the same gNB, or a ready cell from a different gNB, where activity can be restarted via the radio connection re-establishment process (i.e., the UE remains in connected mode), since the previous UE context can be obtained through inter-cell communication.

[0119] ● Compared to the existing LTE RLF recovery process, the additional process involves the UE determining the optimal cell based on different network-configurable methods.

[0120] ○ The UE can select only cells that support SUL carriers;

[0121] The UE can select a cell by considering both DL and UL radio link quality measurements. For each cell, the UE can estimate the UL radio link quality for each carrier belonging to the same cell, considering the carrier frequency, or by collecting measurements provided by the network, or by utilizing historical measurement data, etc. In one example, assuming a -90 dBm DL RSR threshold is configured for candidate cell selection, two candidate cells are available to the UE. For cell 1, which is configured with both SUL and NR UL carriers, the DL RSRP is measured at -85 dBm. The SUL carrier provides a path gain of approximately 7 dB compared to the NR UL carrier. In UL, cell 2 is not configured with an SUL carrier. Its measured DL RSRP is approximately -82 dBm. In this case, the UE should select cell 1 because cell 1 has 4 dB better uplink radio quality than cell 2. In this example, this makes sense given the fact that an RLF is triggered upon uplink RLC retransmission timeout, as UL measurements are more important than DL measurements for cell selection.

[0122] ○ The UE can select the optimal cell purely based on DL radio channel quality measurements; and / or

[0123] ○The UE can also consider the load measurement of the cell and the load of each carrier belonging to the same cell.

[0124] In the seventh embodiment, if an RLF (i.e., an RLC retransmission to a given configurable threshold) is triggered due to an RLC retransmission failure on a specific UL carrier, or on all UL carriers belonging to the same cell, the network can configure the UE. When an RLF is triggered, the same recovery action as described in the sixth embodiment is applied.

[0125] In the eighth embodiment, when an RLF is triggered, if no ready cell is available for radio connection re-establishment, the UE leaves the RRC connected state and remains in the RRC idle state. The UE selects the best unavailable cell. The selection of the best cell uses the same method as in the sixth embodiment.

[0126] In the ninth embodiment, when the RA procedure for radio connection reconstruction for a UE is determined to be an NR cell with a SUL carrier, the network can configure one of the following strategies for the RA procedure:

[0127] ●The UE should always select the SUL carrier for RACH access in the target cell.

[0128] ● Regardless of whether the corresponding PRACH resource is on the SUL carrier or the NR UL carrier, the UE should select the nearest PRACH transmission opportunity.

[0129] ● The UE should still select the UL carrier for RACH access based on the existing policy. For example, if the DL RSRP is higher than the pre-configured threshold, the UE selects the NR UL carrier; otherwise, it selects the SUL carrier.

[0130] ●The UE can initiate RACH access in parallel on two carriers, ensuring that RACH access on at least one carrier can be acknowledged. When one carrier is acknowledged, RACH access on the other carrier is stopped.

[0131] In the tenth embodiment, the specific configuration of radio link maintenance at the RLF can be configured via UE-specific RRC signaling or broadcast SIB.

[0132] Figure 6 The illustration shows a UE 200 according to one or more embodiments. The UE 200 includes an antenna or antenna array 210 having a plurality of antennas 215, a transceiver 220 for communicating with a base station, and, for example, for performing... Figure 2 and Figure 4 The UE processing circuit 230 for any of the steps depicted, and the UE memory 240 for storing corresponding instructions to be executed by the UE processing circuit 240.

[0133] Figure 7 The illustration shows a base station or gNB 100 according to one or more embodiments. The base station 100 includes an antenna or antenna array 110 having a plurality of antennas 115, a transceiver 120 for communicating with a UE, and, for example, for performing... Figure 1 and Figure 3 The base station processing circuit 130 for any of the steps depicted, and the base station memory 140 for storing corresponding instructions to be executed by the base station processing circuit 140.

[0134] refer to Figure 10According to an embodiment, the communication system includes a telecommunications network 3210, such as a 3GPP-type cellular network, which includes an access network 3211, such as a radio access network, and a core network 3214. The access network 3211 includes multiple base stations 3212a, 3212b, and 3212c (such as NBs, eNBs, gNBs, or other types of wireless access points), each with a defined corresponding coverage area 3213a, 3213b, and 3213c. Each base station 3212a, 3212b, and 3212c can be connected to the core network 3214 via a wired or wireless connection 3215. A first user equipment (UE) 3291 located in coverage area 3213c is configured to wirelessly connect to or be paged by the corresponding base station 3212c. A second UE 3292 located in coverage area 3213a can wirelessly connect to the corresponding base station 3212a. Although multiple UEs 3291 and 3292 are illustrated in this example, the disclosed embodiments are equally applicable to situations where only one UE is in the coverage area or where only one UE is connected to the corresponding base station 3212.

[0135] Telecommunications network 3210 is itself connected to host computer 3230, which may be embodied in the hardware and / or software of a standalone server, a cloud-implemented server, a distributed server, or as processing resources in a server farm. Host computer 3230 may be owned or controlled by a service provider, or may be operated by or on behalf of the service provider. Connections 3221, 3222 between telecommunications network 3210 and host computer 3230 may extend directly from core network 3214 to host computer 3230, or may traverse via optional intermediate network 3220. Intermediate network 3220 may be one or more of public, private, or hosted networks; intermediate network 3220 (if any) may be a backbone network or the Internet; in particular, intermediate network 3220 may include two or more subnetworks (not shown).

[0136] Figure 10The communication system as a whole enables connectivity between one of the connected UEs 3291 and 3292 and the host computer 3230. This connectivity can be described as an over-the-top (OTT) connection 3250. The host computer 3230 and the connected UEs 3291 and 3292 are configured to transmit data and / or signaling via the OTT connection 3250, using access network 3211, core network 3214, any intermediate network 3220, and possibly additional infrastructure (not shown) as intermediaries. The OTT connection 3250 can be transparent in the sense that the participating communication devices through which the OTT connection 3250 passes are unaware of the routes of the uplink and downlink communications. For example, the base station 3212 may not be notified or need not be notified of past routes for incoming downlink communications containing data originating from the host computer 3230 that will be forwarded (e.g., transferred) to the connected UE 3291. Similarly, base station 3212 does not need to know the future route of outgoing uplink communication originating from UE 3291 toward host computer 3230.

[0137] According to the embodiments, reference will now be made to Figure 11 Example implementations of the UE, base station, and host computer discussed in the preceding paragraphs are described. In the communication system 3300, the host computer 3310 includes hardware 3315, which includes a communication interface 3316 configured to establish and maintain wired or wireless connections with interfaces to different communication devices of the communication system 3300. The host computer 3310 also includes processing circuitry 3318, which may have storage and / or processing capabilities. In particular, the processing circuitry 3318 may include one or more programmable processors, application-specific integrated circuits, field-programmable gate arrays, or combinations thereof (not shown) suitable for executing instructions. The host computer 3310 also includes software 3311, which is stored in or accessible by the host computer 3310 and executable by the processing circuitry 3318. The software 3311 includes a host application 3312. Host application 3312 is operable to provide services to remote users, such as UE 3330 connected via OTT connection 3350 terminated between UE 3330 and host computer 3310. When providing services to remote users, host application 3312 can provide user data transmitted using OTT connection 3350.

[0138] The communication system 3300 also includes a base station 3320, which is provided in the telecommunications system and includes hardware 3325 enabling it to communicate with a host computer 3310 and a UE 3330. Hardware 3325 may include a communication interface 3326 for establishing and maintaining wired or wireless connections to different communication devices of the communication system 3300, and for establishing and maintaining connections with areas served by the base station 3320. Figure 11 The UE 3330 (not shown) has at least a radio interface 3327 for a wireless connection 3370. A communication interface 3326 can be configured to facilitate a connection 3360 to a host computer 3310. The connection 3360 can be direct, or it can be via the core network of a telecommunications system (…). Figure 11 (not shown), and / or via one or more intermediate networks outside the telecommunications system. In the illustrated embodiment, the hardware 3325 of base station 3320 also includes processing circuitry 3328, which may include one or more programmable processors, application-specific integrated circuits, field-programmable gate arrays, or combinations of these adapted to execute instructions (not shown). Base station 3320 further has software 3321 stored internally or accessible via an external connection.

[0139] The communication system 3300 also includes the previously mentioned UE 3330. Its hardware 3335 may include a radio interface 3337 configured to establish and maintain a wireless connection 3370 with a base station serving the coverage area currently occupied by the UE 3330. The hardware 3335 of the UE 3330 also includes processing circuitry 3338, which may include one or more programmable processors, application-specific integrated circuits, field-programmable gate arrays, or combinations thereof (not shown) suitable for executing instructions. The UE 3330 also includes software 3331, which is stored in or accessible by the UE 3330 and executable by the processing circuitry 3338. The software 3331 includes a client application 3332. The client application 3332 may be operable to provide services to human or non-human users via the UE 3330, with the support of the host computer 3310. In host computer 3310, the executing host application 3312 can communicate with the executing client application 3332 via OTT connection 3350 terminated between UE 3330 and host computer 3310. When providing services to a user, client application 3332 can receive request data from host application 3312 and provide user data in response to the request data. OTT connection 3350 can transfer both request data and user data. Client application 3332 can interact with the user to generate the user data it provides.

[0140] Notice, Figure 11The host computer 3310, base station 3320, and UE 3330 shown in the diagram can be respectively equivalent to... Figure 10 The host computer 3230, one of base stations 3212a, 3212b, and 3212c, and one of UEs 3291 and 3292. That is to say, the internal operations of these entities can be as follows: Figure 11 As shown, and independently, the surrounding network topology can be Figure 10 The network topology.

[0141] exist Figure 11 In this diagram, OTT connection 3350 is abstractly depicted to illustrate communication between host computer 3310 and user equipment 3330 via base station 3320, without explicitly mentioning any intermediary devices and the precise routing of messages via these devices. The network infrastructure can determine the route, which can be configured to be hidden from the UE 3330 or the service provider operating the host computer 3310, or both. When OTT connection 3350 is active, the network infrastructure can further make decisions, through which it dynamically changes the route (e.g., based on network reconfiguration or load balancing considerations).

[0142] The wireless connection 3370 between UE 3330 and base station 3320 is based on the teachings of embodiments described throughout this disclosure.

[0143] One or more embodiments in various examples improve the performance of OTT services provided to UE 3330 using OTT connection 3350, wherein wireless connection 3370 forms the final segment. More precisely, the teachings of these embodiments can improve latency or power consumption, and thereby provide benefits such as better responsiveness and extended battery life.

[0144] For the purpose of monitoring data rate, latency, and other factors improved by one or more embodiments, a measurement process may be provided. Optional network functionality may further exist for reconfiguring the OTT connection 3350 between host computer 3310 and UE 3330 in response to changes in measurement results. The measurement process and / or network functionality for reconfiguring the OTT connection 3350 may be implemented using software 3311 of host computer 3310, or software 3331 of UE 3330, or both. In embodiments, sensors (not shown) may be deployed in or associated with communication devices traversed by the OTT connection 3350; the sensors may participate in the measurement process by providing values ​​of the monitored quantities illustrated above, or by providing values ​​of other physical quantities from which software 3311, 3331 can calculate or estimate the monitored quantities. Reconfiguration of the OTT connection 3350 may include message formatting, retransmission settings, preferred routing, etc.; reconfiguration does not need to affect base station 3320, and this may be unknown or imperceptible to base station 3320. Such processes and functionalities are likely known and practiced in the art. In some embodiments, the measurement may involve proprietary UE signaling, thereby facilitating the host computer 3310 to measure throughput, propagation time, latency, etc. Measurements can be made because software 3311, 3331 uses OTT connection 1550 to transmit messages (especially empty or "dummy" messages) while it monitors propagation time, errors, etc.

[0145] Figure 12 This is a flowchart illustrating a method implemented in a communication system according to one embodiment. The communication system includes a host computer, a base station, and a UE, which can be the same as those described with reference to Figures 32 and 33. For the sake of simplicity, this section will only include descriptions of... Figure 12 Referring to the accompanying drawings. In the first step 3410 of the method, the host computer provides user data. In an optional sub-step 3411 of the first step 3410, the host computer provides user data by executing a host application. In the second step 3420, the host computer initiates a transmission carrying user data to the UE. In an optional third step 3430, in accordance with the teachings of the embodiments described throughout this disclosure, the base station transmits the user data carried in the transmission initiated by the host computer to the UE. In an optional fourth step 3440, the UE executes a client application associated with the host application executed by the host computer.

[0146] Figure 13This is a flowchart illustrating a method implemented in a communication system according to one embodiment. The communication system includes a host computer, a base station, and a UE, which may be those described with reference to Figures 32 and 33. For the sake of simplicity, reference to Figure 35 will be included only in this section. In a first step 3510 of the method, the host computer provides user data. In an optional sub-step (not shown), the host computer provides the user data by executing a host application. In a second step 3520, the host computer initiates a transmission carrying the user data to the UE. According to the teachings of the embodiments described throughout this disclosure, the transmission may be carried out via a base station. In an optional third step 3530, the UE receives the user data carried in the transmission.

[0147] Figure 14 This is a flowchart illustrating a method implemented in a communication system according to one embodiment. The communication system includes a host computer, a base station, and a UE, which may be the host computer, base station, and UE described with reference to Figures 32 and 33. For the sake of simplicity, reference to Figure 36 will be included only in this section. In an optional first step 3610 of the method, the UE receives input data provided by the host computer. Additionally or alternatively, in an optional second step 3620, the UE provides user data. In an optional sub-step 3621 of the second step 3620, the UE provides user data by executing a client application. In a further optional sub-step 3611 of the first step 3610, the UE executes a client application that provides user data as a response to the received input data provided by the host computer. When providing user data, the executed client application may further consider user input received from the user. Regardless of the specific manner in which user data is provided, in an optional third sub-step 3630, the UE initiates the transmission of user data to the host computer. In the fourth step 3640 of the method, the host computer receives user data transmitted from the UE in accordance with the teachings of the embodiments described throughout this disclosure.

[0148] Figure 15 This is a flowchart illustrating a method implemented in a communication system according to one embodiment. The communication system includes a host computer, a base station, and a UE, which may be those host computers, base stations, and UEs described with reference to Figures 32 and 33. For the sake of simplicity, reference to Figure 37 will be included only in this section. In an optional first step 3710 of the method, the base station receives user data from the UE in accordance with the teachings of the embodiments described throughout this disclosure. In an optional second step 3720, the base station initiates a transmission of the received user data to the host computer. In a third step 3730, the host computer receives the user data carried in the transmission initiated by the base station.

[0149] Another embodiment:

[0150] 1. A method for handling radio link failures in a user equipment (UE), wherein the UE is connected to a radio communication network via a plurality of uplink UL carriers, the method comprising:

[0151] - Individually monitor retransmission of Radio Link Control (RLC) data packets for multiple UL carriers;

[0152] - Determine a fault in the RLC data packet transmission of one of the UL carriers; and

[0153] - Provide information indicating the fault and the UL carrier.

[0154] 2. The method as described in the foregoing embodiments, wherein the plurality of UL carriers includes a primary UL carrier and an auxiliary UL SUL carrier.

[0155] 3. The method described in the foregoing embodiments, wherein the primary carrier is a New Radio (NR) UL carrier.

[0156] 4. The method as described in any of the foregoing embodiments, wherein the UE transmits information to the radio communication network indicating a radio link failure (RLF) and the UL carrier affected by the RLF.

[0157] 5. The method as described in any of the foregoing embodiments, wherein if a maximum number of RLC retransmissions of RLC data packets for the carrier has been reached, then the failure of RLC data packet transmission for the carrier is determined.

[0158] 6. The method as described in the foregoing embodiments, wherein each of the plurality of carriers is associated with a maximum quantity, for example, such that a first maximum quantity is associated with the primary UL carrier and a second maximum quantity is associated with the SUL carrier.

[0159] 7. The method as described in the foregoing embodiments, wherein the first maximum quantity is different from the second maximum quantity.

[0160] 8. The method as described in any of the foregoing embodiments, wherein the UE receives configuration from the network to trigger a radio link failure (RLF) for a different UL carrier.

[0161] 9. The method as described in the foregoing embodiments, wherein the first configuration for triggering the RLF of the primary UL carrier is different from the second configuration for triggering the RLF of the SUL carrier.

[0162] 10. The method as described in the foregoing embodiments, wherein the configuration for triggering the RLF of the primary UL carrier and the configuration for triggering the RLF of the SUL carrier are different because the first configuration includes a first maximum number of RLC retransmissions and the second configuration includes a second maximum number of RLC retransmissions, wherein the first maximum number and the second maximum number are different.

[0163] 11. The method as described in the foregoing embodiments, wherein the first maximum quantity is higher than the second maximum quantity.

[0164] 12. The method as described in any of the foregoing embodiments, wherein the UE includes an RLC entity for performing RLC functions and an RRC entity for performing RRC functions, wherein the RLC entity performs the following steps: individually monitoring the retransmission of RLC data packets for a plurality of UL carriers; and determining a fault in the transmission of RLC data packets with respect to one of the UL carriers, and providing the RRC entity with information indicating the fault and the UL carrier.

[0165] 13. The method as described in the foregoing embodiments, wherein the RRC entity performs a Radio Link Failure (RLF) at the radio communication network.

[0166] 14. A method for handling a radio link failure in a user equipment (UE) (200), wherein the UE is connected to a radio communication network by means of a plurality of uplink UL carriers, the method comprising:

[0167] - Perform retransmission of an RLC data packet on at least two of the plurality of UL carriers;

[0168] - For retransmission of radio link control (RLC) data packets jointly monitored by two UL carriers; and

[0169] - Provides information indicating common RLF.

[0170] 15. The method as described in the foregoing embodiments, wherein the UE provides:

[0171] - Information indicating a Radio Link Failure (RLF), but not information about UL carriers not affected by the RLF, if the UE is configured to monitor the retransmission for both of the at least two UL carriers; and

[0172] - Information about the UL carrier affected by the RLF and the UL carrier and RLF affecting the radio communication network, if the UE is configured to monitor the retransmission individually for the at least two UL carriers.

[0173] 16. The method as described in embodiments 14-15 above, wherein the UE is configured to perform at least one of the following:

[0174] - Count RLC retransmissions on one or more specific carriers (e.g., NR UL carriers or SUL carriers) to report RLC transmission failures; and

[0175] - Count the RLC transmissions on all carriers in order to report RLC retransmission failures.

[0176] 17. The method as described in any of the foregoing embodiments, wherein in the event of a failure in the RLC data packet transmission with respect to the primary UL carrier, one of the following steps is performed:

[0177] - If the SUL carrier is configured (and active), a scheduling request (SR) transmission on the SUL carrier is triggered, thereby instructing the UE to switch to the SUL carrier for UL data transfer; and

[0178] - Otherwise, trigger access to the random access channel RACH on the SUL carrier, thereby indicating the fault; or

[0179] - Signal the following information to the network (gNB): The data (RLC) transmission is blocked on the primary (NR) carrier (signaling options may include RRC, MAC CE or other L1 / L2 signaling means; the signaling may be transmitted on the SUL carrier).

[0180] 18. The method as described in the foregoing embodiments, wherein if the downlink channel quality (RSRP) is below a certain threshold, then only the SR transmission on the SUL carrier is triggered.

[0181] 19. The method as described in any of the foregoing embodiments, wherein if a SUL RLF is triggered, the UE first performs a cell search to determine a suitable cell for radio link reconstruction.

[0182] 20. The method as described in the foregoing embodiments, wherein the UE selects a prepared cell, the cell may be the same cell, different cells from the same base station (gNB), or prepared cells from different base stations (gNB).

[0183] 21. The method as described in the foregoing embodiments, wherein the UE is configured to:

[0184] - Select a cell from one or more cells that support SUL carriers;

[0185] - Cell selection is based on measurements of both DL and UL radio link quality;

[0186] - Select cells solely based on measurements of the DL radio channel quality; and / or

[0187] - Select a cell based on the load measurement of the cell and the load of each carrier belonging to the same cell.

[0188] 22. The method as described in the foregoing embodiments, wherein if the first cell is configured with a SUL carrier and a primary UL carrier, and the second cell is not configured with a SUL carrier, then the UE performs:

[0189] -Measure the quality of the DL radio link and the UL radio link;

[0190] - Determine whether the DL radio link quality of the two cells is higher than a certain minimum quality threshold, and / or whether the SUL carrier provides a greater path gain than the primary UL carrier; and

[0191] - If certain, select the first cell.

[0192] 23. A method for handling radio link failures in a base station gNB (100) of a radio communication network, wherein a UE is connected to the gNB via a plurality of uplink UL carriers, the method comprising:

[0193] - Receive information about a fault in the transmission of RLC data packets in one of the UL carriers, wherein the fault has been individually determined by monitoring the retransmission of RLC data packets via radio link control for at least two of the plurality of UL carriers individually.

[0194] 24. The method as described in the foregoing embodiments, wherein the plurality of UL carriers includes a primary UL carrier and an auxiliary UL SUL carrier.

[0195] 25. The method as described in the foregoing embodiments, wherein the primary carrier is a New Radio (NR) UL carrier.

[0196] 26. The method as described in any of the preceding embodiments 23-25, wherein the gNB receives information from the radio communication network indicating a radio link failure (RLF) and the UL carrier affected by the RLF.

[0197] 27. As described in any of the preceding embodiments 23-26, send a configuration to the UE indicating the maximum number of RLC retransmissions of RLC data packets to trigger (or assume) a failure in the RLC data packet transmission of the carrier.

[0198] 28. The method as described in the foregoing embodiments, wherein the configuration includes a first maximum number associated with the primary UL carrier and a second maximum number associated with the SUL carrier.

[0199] 29. The method as described in the foregoing embodiments, wherein the first maximum quantity is different from the second maximum quantity.

[0200] 30. The method as described in any of the preceding embodiments 23-29, wherein the gNB transmits a configuration to the UE to trigger a radio link failure (RLF) on a different UL carrier.

[0201] 31. The method as described in the foregoing embodiments, wherein the first configuration of the RLF that triggers the primary UL carrier is different from the second configuration of the RLF that triggers the SUL carrier.

[0202] 32. The method as described in the foregoing embodiments, wherein the configuration for triggering the RLF of the primary UL carrier and the configuration for triggering the RLF of the SUL carrier are different because the first configuration includes a first maximum number of RLC retransmissions and the second configuration includes a second maximum number of RLC retransmissions, wherein the first maximum number and the second maximum number are different.

[0203] 33. The method as described in the foregoing embodiments, wherein the first maximum quantity is higher than the second maximum quantity.

[0204] 34. A method for handling radio link failures in a gNB (100), wherein the gNB is connected to the UE via a plurality of uplink UL carriers, the method comprising:

[0205] - Receive information from the UE indicating a common RLF, wherein the common RLF originates from the retransmission of an RLC data packet performed at the UE for joint monitoring of at least two of the plurality of UL carriers on two UL carriers.

[0206] 35. The method as described in the foregoing embodiments, wherein the gNB UE receives:

[0207] - Information indicating a Radio Link Failure (RLF), but not information about UL carriers not affected by the RLF, if the gNB is configured to monitor the retransmission for both of the at least two UL carriers; and

[0208] - Information about the UL carrier affected by the RLF and the UL carrier and RLF affecting the radio communication network, if the gNB is configured to monitor the retransmission individually for the at least two UL carriers.

[0209] 36. The method as described in any of the foregoing embodiments 34-35, wherein the gNB configures the UE to perform at least one of the following:

[0210] - Count RLC retransmissions on one or more specific carriers (e.g., NR UL carriers or SUL carriers) to report RLC transmission failures; and

[0211] - Count the RLC transmissions on all carriers in order to report RLC retransmission failures.

[0212] 37. The method as described in any of the foregoing embodiments 23-36, wherein in the event of a failure in the RLC data packet transmission with respect to the primary UL carrier, one of the following steps is performed:

[0213] - If the SUL carrier is configured (and active), a scheduling request (SR) transmission is received on the SUL carrier, thereby instructing the UE to switch to the SUL carrier for UL data transfer; and

[0214] Otherwise, receiving access to the random access channel RACH on the SUL carrier indicates the fault.

[0215] 38. The method as described in any of the foregoing embodiments 23-37, wherein the gNB configures the UE to:

[0216] - Select a cell from one or more cells that support SUL carriers;

[0217] - Cell selection is based on measurements of both DL and UL radio link quality;

[0218] - Select cells solely based on measurements of the DL radio channel quality; and / or

[0219] - Select a cell based on the load measurement of the cell and the load of each carrier belonging to the same cell.

[0220] 39. The method as described in the foregoing embodiments further includes configuring a SUL carrier and a primary UL carrier for the first cell, and not configuring a SUL carrier for the second cell, wherein the UE performs:

[0221] -Measure the quality of the DL and the UL radio link;

[0222] - Determine whether the DL radio link quality of the two cells is higher than a certain minimum quality threshold, and / or whether the SUL carrier provides a greater path gain than the primary UL carrier; and

[0223] - If certain, select the first cell.

[0224] 40. A user equipment (UE) for handling radio link failures, wherein the UE is connected to a radio communication network via a plurality of uplink UL carriers, the UE including processing circuitry and memory, wherein the processing circuitry is configured to:

[0225] - Individually monitor retransmission of Radio Link Control (RLC) data packets for multiple UL carriers;

[0226] - Determine a fault in the RLC data packet transmission of one of the UL carriers; and

[0227] - Provide information indicating the fault and the UL carrier.

[0228] 41. A user equipment (UE) for handling radio link failures, wherein the UE is connected to a radio communication network via a plurality of uplink UL carriers, the UE (200) including processing circuitry and memory, wherein the processing circuitry is configured to:

[0229] - Perform retransmission of an RLC data packet on at least two of the plurality of UL carriers;

[0230] - For retransmission of radio link control (RLC) data packets jointly monitored by two UL carriers; and

[0231] - Provides information indicating common RLF.

[0232] 42. A user equipment (UE) for handling radio link failures, wherein the UE is connected to a radio communication network by means of a plurality of uplink UL carriers, and wherein the UE is adapted to perform the method as described in any one of the foregoing embodiments 1-24.

[0233] 43. A base station gNB for handling radio link failures in a radio communication network, wherein a UE is connected to the gNB via a plurality of uplink UL carriers, the base station including processing circuitry and a memory, wherein the processing circuitry is configured to:

[0234] - Receive information about a fault in the transmission of RLC data packets in one of the UL carriers, wherein the fault has been individually determined by monitoring the retransmission of RLC data packets via radio link control for at least two of the plurality of UL carriers individually.

[0235] 44. A base station gNB for handling radio link failures in a radio communication network, wherein a UE is connected to the gNB via a plurality of uplink UL carriers, the base station including processing circuitry and a memory, wherein the processing circuitry is configured to:

[0236] - Receive information from the UE indicating a common RLF, wherein the common RLF originates from the retransmission of an RLC data packet performed at the UE for joint monitoring of at least two of the plurality of UL carriers on two UL carriers.

[0237] 45. A base station gNB for a radio communication network, wherein the gNB is connected to a UE via a plurality of uplink UL carriers, and wherein the UE is adapted to perform the method as described in any of the preceding embodiments 23-39.

[0238] 46. ​​A communication system comprising a host computer, the host computer including: processing circuitry configured to provide user data; and a communication interface configured to forward the user data to a cellular network for transmission to a user equipment (UE), wherein the cellular network includes a base station (gNB) having a radio interface and processing circuitry, the processing circuitry of the base station being configured to:

[0239] - Receive information about a fault in the transmission of RLC data packets in one of the UL carriers, wherein the fault has been individually determined by monitoring the retransmission of RLC data packets via radio link control for at least two of the plurality of UL carriers individually.

[0240] 47. A communication system comprising a host computer, the host computer including: processing circuitry configured to provide user data; and a communication interface configured to forward the user data to a cellular network for transmission to a user equipment (UE), wherein the cellular network includes a base station (gNB) having a radio interface and processing circuitry, the processing circuitry of the base station being configured to:

[0241] - Receive information from the UE indicating a common RLF, wherein the common RLF originates from the retransmission of an RLC data packet performed at the UE for joint monitoring of at least two of the plurality of UL carriers on two UL carriers.

[0242] 48. The communication system as described in Embodiments 46 or 47 further includes a base station.

[0243] 49. The communication system of embodiment 48 further includes a UE, wherein the UE is configured to communicate with the base station.

[0244] 50. The communication system as described in Example 49, wherein:

[0245] The processing circuitry of the host computer is configured to execute a host application, thereby providing the user data; and

[0246] - The UE includes processing circuitry configured to execute client applications associated with the host application.

[0247] 51. A method implemented in a communication system, the communication system comprising a host computer, a base station, and a user equipment (UE), the method comprising:

[0248] - Provide user data at the host computer; and

[0249] - At the host computer, a transmission carrying the user data is initiated to the UE via a cellular network including the base station, wherein the base station performs one of the following:

[0250] - Receive information from the UE indicating a common RLF, wherein the common RLF originates from retransmission performed at the UE for jointly monitoring an RLC data packet on at least two of the plurality of UL carriers on two UL carriers; and

[0251] - Receive information from the UE regarding a fault in the transmission of RLC data packets in one of the UL carriers, wherein the fault has been individually determined by monitoring the retransmission of RLC data packets via radio link control for at least two of the plurality of UL carriers individually.

[0252] 52. The method as described in Example 51, further comprising:

[0253] - The user data is transmitted at the base station.

[0254] 53. The method of embodiment 52, wherein the user data is provided at the host computer by executing a host application, the method further comprising:

[0255] - At the UE, execute the client application associated with the host application.

[0256] 54. A communication system, comprising a host computer, the host computer comprising:

[0257] - A processing circuit configured to provide user data; and

[0258] - A communication interface configured to forward user data to a cellular network for transmission to a user equipment (UE).

[0259] -The UE includes a radio interface and processing circuitry, the processing circuitry of which is configured to perform one of the following:

[0260] - Monitor retransmissions of Radio Link Control (RLC) data packets individually for multiple UL carriers; determine a fault in the RLC data packet transmission for one of the UL carriers, and provide information indicating the fault and the UL carrier; and

[0261] - Perform retransmission of a certain RLC data packet on at least two of the plurality of UL carriers; monitor the retransmission of radio link control RLC data packets on both UL carriers; and provide information indicating the common RLF.

[0262] 55. The communication system as described in Example 54 further includes a UE.

[0263] 56. The communication system as described in Example 55, wherein the cellular network further includes a base station configured to communicate with the UE.

[0264] 57. The communication system as described in Embodiment 55 or 56, wherein:

[0265] The processing circuitry of the host computer is configured to execute a host application, thereby providing the user data; and

[0266] - The UE's processing circuitry is configured to execute client applications associated with the host application.

Claims

1. A method for handling a radio link failure in a user equipment (UE) (200), wherein the UE is connected to a radio communication network by means of a plurality of uplink UL carriers (220, 230), the method comprising: - Retransmission of each monitoring (S41) radio link control (RLC) data packet for each of multiple UL carriers; - Determine (S42) a fault in the RLC data packet transmission of one of the UL carriers; as well as - Provide (S43) information indicating the fault of the UL carrier; If the maximum number of RLC retransmissions of RLC data packets for the carrier has been reached, then the failure of the RLC data packet transmission of the carrier is determined. Each of the plurality of carriers is associated with a maximum number of RLC retransmissions of RLC data packets, such that a first maximum number is associated with the primary UL carrier and a second maximum number is associated with the secondary UL SUL carrier, wherein the first maximum number is different from the second maximum number.

2. The method of claim 1, wherein the primary UL carrier is a New Radio (NR) UL carrier.

3. The method of any one of claims 1-2, wherein the UE transmits information to the radio communication network indicating a radio link failure (RLF) and the UL carrier affected by the RLF.

4. The method of any one of claims 1-2, wherein the UE receives one or more configurations from the network to trigger a radio link failure (RLF) for a different UL carrier.

5. The method of claim 4, wherein the first configuration of the RLF that triggers the primary UL carrier is different from the second configuration of the RLF that triggers the SUL carrier.

6. The method of any one of claims 1-2, wherein the UE (200) includes an RLC entity for performing RLC functions and an RRC entity for performing RRC functions, wherein the RLC entity performs the following steps: individually monitoring the retransmission of RLC data packets for a plurality of UL carriers; and determining a fault in the transmission of RLC data packets with respect to one of the UL carriers, and providing the RRC entity with the information indicating the fault of the UL carrier.

7. The method of claim 6, wherein the RRC entity performs a Radio Link Failure (RLF) at the radio communication network.

8. The method of claim 1, comprising: - Perform (S61) retransmission of an RLC data packet on at least two of the plurality of UL carriers; - Retransmission of radio link control (RLC) data packets for common monitoring (S62) of all carriers in the at least two UL carriers; and - Provides (S63) information indicating common RLF.

9. The method of claim 8, wherein the UE provides: - Information indicating a Radio Link Failure (RLF) but not information about UL carriers not affected by the RLF, if the UE is configured to monitor the retransmission for at least two UL carriers; and - Information about the UL carrier affected by the RLF and the RLF, if the UE is configured to monitor the retransmission individually for the at least two UL carriers.

10. The method of any one of claims 8-9, wherein the UE (200) is configured to perform at least one of the following: - A common count of RLC retransmissions associated with all carriers in at least two of the plurality of UL carriers, in order to report the common RLF; and - RLC retransmissions associated with each of the at least two of the plurality of UL carriers are counted separately in order to report the RLF of the UL carriers that are affected individually.

11. The method of claim 10, wherein the at least two carriers are an NR UL carrier and the SUL carrier.

12. A method for handling radio link failures in a base station gNB (100) of a radio communication network, wherein a UE (200) is connected to the gNB via a plurality of uplink UL carriers, the method comprising: - Receive (S51) information about a fault in the transmission of RLC data packets in one of the UL carriers, wherein the fault has been determined by monitoring the retransmission of RLC data packets for each of at least two of the plurality of UL carriers via radio link control; - The method further includes: sending to the UE a configuration indicating a maximum number of RLC retransmissions of RLC data packets to assume and / or to trigger the failure of RLC data packet transmission of the carrier, wherein the configuration includes a first maximum number associated with a primary UL carrier and a second maximum number associated with a secondary UL SUL carrier, wherein the first maximum number is different from the second maximum number.

13. A user equipment (UE) (200) adapted to perform the method as described in any one of claims 1-11.

14. A base station gNB (100) of a radio communication network, adapted to perform the method as described in claim 12.

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