Device and user equipment for wireless communication system

Abstract

An apparatus for a wireless communication system comprises at least one processor and a memory storing instructions, which, when executed by the at least one processor, causes the apparatus to at least configure a radio link control (RLC) failure configuration for a user equipment, wherein the RLC failure configuration defines how the user equipment should react to an RLC failure of a first logical channel associated with the user equipment.

Description

Technical Field

[0001] The present disclosure relates to an apparatus for a wireless communication system.

[0002] The present disclosure also relates to a user equipment (UE).

[0003] The present disclosure also relates to a method of operating an apparatus for a wireless communication system.

[0004] The present disclosure also relates to a method of operating a user equipment. Background Art

[0005] A wireless communication system can be used, for example, for the wireless exchange of information between two or more entities. Summary of the Invention

[0006] The scope of protection sought by the various embodiments of the present disclosure is set forth in the independent claims. Exemplary embodiments and features (if any) described in this specification that do not fall within the scope of the independent claims will be construed as examples useful for understanding the various exemplary embodiments of the present disclosure.

[0007] Some embodiments relate to an apparatus for a wireless communication system, including at least one processor and a memory storing instructions that, when executed by the at least one processor, cause the apparatus to configure at least a radio link control (RLC) failure configuration for a user equipment, the RLC failure configuration defining how the user equipment should react to an RLC failure of a first logical channel associated with the user equipment.

[0008] In some embodiments, the apparatus or its functionality can be provided separately in a network element of a communication system, such as in a base station (e.g., a gNodeB (gNB)).

[0009] In some embodiments, the apparatus or its functionality according to an embodiment can be used separately for or within a wireless communication system that is based on or at least partially adheres to the 3rd Generation Partnership Project (3GPP) radio standards, such as 4G E-UTRAN or 5G NR (5th Generation New Radio). In some embodiments, the apparatus or its functionality according to an embodiment can be used separately for a radio link failure (RLF) procedure of a 5G NR-based communication system.

[0010] As an example, one triggering condition for RLF in the Uu interface currently defined for 5G NR, for instance, is characterized as follows: When using the RLC acknowledged mode (AM), it is indicated from the radio link control (RLC) layer that the maximum number of RLC retransmissions has been reached. According to this triggering condition, the maximum number of retransmissions in the RLC is configured by using the parameter "maxRetxThreshold", which is configured in the information element (IE) "RLC-Config" according to 3GPP TS 38.331 (see, for example, 3GPP TS 38.331 V15.8.0 (2019-12)), and is used by the transmission side of the AM RLC entity to limit the total number of retransmissions of the RLC protocol data unit (PDU). Detecting RLF in this case can cause the UE to transit to the RRC_IDLE state, or initiate a radio resource control (RRC) connection re-establishment procedure.

[0011] Currently, for example, the maximum number of retransmissions parameter defined for 5G NR (i.e., maxRetxThreshold configured in RLC-Config) is applied to the RLC AM defined in 3GPP TS 38.331, where the value t1 corresponds to 1 retransmission, the value t2 corresponds to 2 retransmissions, and so on. If the maximum number of retransmissions of the RLC entity is reached in an exemplary single-cell scenario, RLF will be declared, which will trigger the UE to re-establish the RRC connection with the NW, as described above. More specifically, when RLF is declared, all radio bearers (RBs) except SRB0 will be suspended. After the RRC connection re-establishment procedure is successfully completed, after receiving the first RRCReconfiguration message, these suspended RBs (i.e., SRB2 and DRB) can be resumed first. Therefore, during the resumption of the DRB, user plane data cannot be transmitted, resulting in an undesired interruption in the running application.

[0012] According to TS 38.331, RLC-Config is included in the IE RLC-BearerConfig, which is used to configure the RLC entity and the corresponding logical channel (LCH) for the uplink in the MAC (except for the link with the PDCP entity). Therefore, different RLC entities can be configured for the UE (e.g., for different logical channels), and these entities can be configured in different ways, for example, having different values for the maximum number of retransmissions.

[0013] In the current definition of RLF, as currently defined for 5G NR for example, an RLC failure of a logical channel / RLC entity (e.g., when maxRetxThreshold is reached) implies the declaration of RLF, which in turn implies the suspension of all DRBs, which will interrupt data transmission on any other DRB.

[0014] As an example, first, when an RLC failure occurs, it may be due to radio conditions and / or protocol issues. In the case of radio problems, this means that even RLC retransmissions cannot help recover from radio losses. Although it can be expected that the radio link monitoring (RLM) process can generally detect radio problems before an RLC failure occurs, the current RLM process, as currently defined for 5G NR for example, is limited to the primary cell (PCell). Therefore, an RLC failure may occur due to radio problems or protocol failures (including configuration problems) on a secondary cell (SCell), rather than due to radio failures only on the PCell.

[0015] In addition, 5G NR also introduces restrictions on the "allowed cells" that an LCH can use, which is different from traditional LTE, because an RLC failure of an LCH may only be a problem for those allowed cells of that LCH (e.g., if they are unlicensed cells, high-frequency cells, etc.), but should not affect other LCHs if they use different cells with higher reliability / better channel quality.

[0016] This means that according to some embodiments, an RLC failure of an RLC entity may not imply that another logical channel cannot be fully supported. This is an aspect that may be particularly relevant when different service types with different quality of service (QoS) requirements coexist in a device. For example, reaching the maxRetxThreshold value from a logical channel for ultra-reliable and low-latency communication (URLLC) services does not necessarily trigger the suspension of a logical channel with more relaxed QoS requirements, such as a logical channel for supporting massive machine type communication (mMTC) and / or enhanced mobile broadband (eMBB) services.

[0017] As another example, second, the re-establishment triggered due to an RLC failure may be a relatively slow process because it may include cell selection (of the old cell or the new cell), a random access process to the selected cell, and several RRC messages to be exchanged. In the case of an RLC failure caused by a protocol / configuration issue, the recovery attempt of the same cell (e.g., by reconfiguring the affected RLC entity) may succeed. However, this can only be initiated after an unnecessary delay due to the re-establishment.

[0018] Some embodiments address aspects such as, for example, a method for handling RLC failures, which aims to recover affected RLC entities (i.e., the RLC entities in which (a) RLC failure(s) is / are detected) more quickly, while they may allow unaffected RLC entities to continue their services.

[0019] According to some embodiments, as already mentioned above, a user equipment may use, for example, an RLC failure configuration provided by being configured via a device according to some embodiments to determine how to react to such an RLC failure.

[0020] According to some embodiments, the RLC failure configuration defines whether the user equipment should notify the network of an RLC failure of a first logical channel.

[0021] According to some embodiments, the RLC failure configuration defines whether the user equipment should notify the network of an RLC failure of a first logical channel when at least a second logical channel associated with the user equipment is operating normally (i.e., not experiencing an RLC failure). According to some embodiments, this may enable at least a second LCH and / or RB associated therewith to remain normal (i.e., uninterrupted) operation, for example instead of declaring an RLF and initiating a re - establishment.

[0022] As an example, for instance, when the second logical channel has not reached a predetermined number of RLC retransmissions (e.g., a first threshold or the maximum number of RLC retransmissions), the second logical channel associated with the user equipment is operating normally.

[0023] According to some embodiments, a UE may be configured with multiple LCHs and / or RLC entities.

[0024] According to some embodiments, a UE may be configured with a separate RLC failure configuration for each LCH, which enables different LCHs with different RLC failure configurations to be provided.

[0025] According to some embodiments, when executed by at least one processor, the instruction further causes the device to explicitly configure an RLC failure configuration for the user equipment.

[0026] According to some embodiments, a user equipment may also be implicitly configured with an RLC failure configuration.

[0027] According to some embodiments (e.g., which may be based on a multi - cell carrier aggregation (CA) / dual - connectivity (DC) scenario), for each LCH configured whether an RLC failure of the LCH should trigger an RLC failure report instead of a re - establishment may be implicitly done, for example based on the allowed cell configuration of the LCH.

[0028] According to some embodiments, the implicit configuration can be part of the allowed cell configuration and can be enabled / disabled for each UE. For example, a configured cell allowed for a faulty LCH (i.e., the first LCH) can be considered faulty and thus suspended / deactivated as long as at least another cell is not faulty and is mapped to at least another LCH: under these conditions, according to some embodiments, an RLC fault report can be triggered without (RRC) re - establishment. According to some embodiments, otherwise, for example if any other cell is also faulty or no other non - faulty LCH is mapped to the cell, an RRC re - establishment is initiated.

[0029] In some embodiments, the allowed cells are unlicensed cells and / or high - frequency cells (e.g., using frequency range FR2 defined in, for example, 3GPP 38.101 - 1, see, for example, 3GPP TS 38.101 - 1 V16.2.0 (2019 - 12), Table 5.1 - 1), because these may be more prone to radio errors. This ensures that if they use different cells with higher reliability / better channel quality, problems on these cells do not affect other LCHs.

[0030] In some embodiments, the RLC fault configuration includes a first threshold, where the user equipment can determine whether to transmit an RLC fault to the network based on the first threshold.

[0031] In some embodiments, the first threshold is the number of predetermined RLC retransmissions.

[0032] According to some embodiments (e.g., which can be based on a single - cell scenario or a multi - cell CA / DC scenario), in view of the existing threshold parameter “maxRetxThreshold”, the first threshold can be considered as a new (additional) threshold, and the existing threshold parameter “maxRetxThreshold” is configured in the information element (IE) “RLC Config” according to 3GPP TS 38.331 (see, for example, 3GPP TS 38.331 V15.8.0 (2019 - 12)).

[0033] According to some embodiments, the first (i.e., new) threshold can be represented, for example, as “maxRetxThreshold_RLCReport” and can be configured for the UE to determine a) when (and / or whether) to report an RLC fault of the first LCH, e.g., if the number of current RLC AM retransmissions reaches the first threshold, and / or b) when (whether) to declare an RLF (e.g., if the number of current RLC AM retransmissions reaches the existing threshold parameter “maxRetxThreshold” defined for RLF detection).

[0034] According to some embodiments, the value of the first threshold "maxRetxThreshold_RLCReport" can be set to be lower than the existing "maxRet_threshold", for example to trigger a report for the first time. According to some embodiments, this enables an attempt to first recover / resolve the RLC failure problem, for example, before declaring RLF and suspending all DRBs, by reconfiguring the protocol parameters of the affected (first) LCH or changing the allowed cells and / or other LCP restrictions.

[0035] According to some embodiments, the RLC failure configuration includes first control information that indicates to the user equipment whether to disable at least one mapping restriction.

[0036] According to some embodiments (e.g., which can be based on a single-cell scenario or a multi-cell CA / DC scenario), after detecting that the RLC entity / LCH has reached a given number of RLC AM retransmissions (e.g., corresponding to the maximum number defined for RLF detection (e.g., the existing "maxRetxThreshold") or a lower configured number, e.g., the first threshold according to some embodiments explained above), if the LCH is configured with LCP (Logical Channel Prioritization) mapping restrictions (e.g., according to allowedCG_list, allowedPriorityLevels, and allowedServingCells, see, for example, 3GPP TS 38.300 V15.8.0 (2019-12), e.g., Chapter 16.1.2), the UE can disable at least one of these mapping restrictions (e.g., instead of triggering RLF), which may be beneficial for obtaining the data to be transmitted as soon as possible, and according to some embodiments, this can be exemplarily referred to as some actions of a "recovery behavior".

[0037] According to some embodiments, the disabling of at least one of these mapping restrictions can be automatically performed, i.e., without an explicit instruction received by the UE.

[0038] According to some embodiments, enabling this "recovery behavior" may depend on the network configuration. The configuration (e.g., according to some embodiments explained above, in addition to a possible first threshold) may indicate which LCP mapping restrictions are to be disabled (e.g., via the information element (IE) "RestrictionsDisableList"). For example, according to some embodiments, after disabling the restrictions according to "allowedServingCells", the UE may fill the UL grant applied to the cell previously affected by the (e.g., first) LCH restriction with data from that LCH. According to some embodiments, conversely, the presence of data of that LCH in the transmission corresponding to that grant may implicitly indicate to the network that the UE has disabled the (LCP mapping) restrictions, and in turn, according to some embodiments explained above, the UE has experienced an RLC failure or the UE has reached the first threshold.

[0039] According to some embodiments, the first control information indicates which of the plurality of mapping restrictions is to be disabled.

[0040] According to some embodiments, the RLC failure configuration includes at least one priority threshold, wherein the user equipment may determine whether to transmit an RLC failure to the network based on the at least one priority threshold.

[0041] According to some embodiments, the user equipment may determine whether to transmit an RLC failure to the network based on the at least one priority threshold and based on at least one of the following: a) the lowest priority of the logical channels associated with the user equipment, b) the priority of the first logical channel.

[0042] According to some embodiments, a first priority threshold and a second priority threshold may be provided.

[0043] According to some embodiments (e.g., which may be based on a single-cell scenario or a multi-cell CA / DC scenario), if the lowest priority of any existing logical channel is lower than a first configuration threshold P1, and the priority of the LCH detecting the RLC failure is higher than a second threshold P2, the UE may send an RLC failure report to the NW. According to some embodiments, if another LCH with a certain (i.e., non-vanishing) QoS difference and / or configuration difference compared to the LCH detecting the RLC failure is configured, the RLC failure of the affected LCH (i.e., the one LCH detecting the RLC failure) does not necessarily imply a failure of the other LCH, and thus, the other LCH should not be affected. Alternatively, according to some embodiments, if the failure occurs in an LCH with a priority higher than or lower than the configuration threshold, an RLC failure report is triggered for each LCH or priority threshold configuration.

[0044] According to some embodiments, when the instructions are executed by at least one processor, the apparatus also causes the device to configure second control information (e.g., a flag) for a user equipment (e.g., an LCH / RLC entity), the second control message indicating at least one of the following: a) the user equipment shall declare a radio link failure after detecting an RLC failure of a first logical channel, b) the user equipment shall transmit an RLC failure of the first logical channel to the network, e.g., in the form of an RLC failure report, c) the user equipment shall declare a radio link failure after detecting an RLC failure of at least one other logical channel other than the first logical channel, d) the user equipment shall transmit an RLC failure report after detecting an RLC failure of at least one other logical channel other than the first logical channel.

[0045] According to some embodiments, the second control information (e.g., a flag) may be set taking into account the QoS requirements of the LCH / RLC entity and / or the set of configured LCH / RGC entities.

[0046] According to some embodiments, when the instructions are executed by at least one processor, the instructions also cause the apparatus to set at least a part of the RLC failure configuration based on at least one user equipment specific condition.

[0047] According to some embodiments, the value of the first threshold and / or the conditions for declaring a radio link failure and / or sending an RLF failure report may be set considering UE specific conditions (e.g., existing services in the UE and optionally QoS requirements). For example, if according to some embodiments, eMBB services and URLLC services coexist, then an RLC failure from only the URLLC service will not declare an RLF.

[0048] According to some embodiments, a first threshold and a second threshold may be configured, and if the highest value of the current number of maximum retransmissions parameter (i.e., "maxRetxThreshold" configured in RLC-Config) defined by 5G NR for an existing logical channel, for example, is higher than the first configured threshold, and the "maxRetxThreshold" value of the LCH detecting the RLC failure is lower than the second configured threshold, then the UE may send an RLC failure report to the NW. In this option, the UE can ensure that there is a significant difference in maxRetxThreshold between the declared LCH (the LCH declaring RLF) and other LCHs. Therefore, the RLC failure of the affected RLC entity should not affect the operation of another LCH.

[0049] According to some embodiments, when the instructions are executed by at least one processor, the instructions also cause the apparatus to broadcast at least a part of the RLC failure configuration, e.g., at least one of the following: a first threshold, a second threshold.

[0050] According to some embodiments, a device or network may broadcast at least a portion of an RLC failure configuration in a system information block (SIB), such as at least one of the following: a first threshold, a second threshold.

[0051] Other embodiments relate to a user equipment including at least one processor and a memory storing instructions that, when executed by the at least one processor, cause the user equipment to at least determine a radio link control (RLC) failure configuration that defines how the user equipment should react to an RLC failure of a first logical channel associated with the user equipment.

[0052] According to some embodiments, determining the RLC failure configuration may include at least one of the following: receiving (e.g., for embodiments with explicit configuration) the RLC failure configuration from a device (e.g., a device according to an embodiment) and / or a gNB, determining the RLC failure configuration through other data and / or configuration (e.g., for embodiments with implicit configuration).

[0053] According to some embodiments, at least some of the RLC failure configurations at the user equipment may also be specified in a standard, such as in a 3GPP technical specification, and / or may be provided by UE implementations.

[0054] According to some embodiments, when executed by the at least one processor, the instructions further cause the user equipment to determine, based on the RLC failure configuration, whether the user equipment should notify the network of an RLC failure of the first logical channel, e.g., when at least a second logical channel associated with the user equipment is operating normally.

[0055] According to some embodiments, when executed by the at least one processor, the instructions further cause the user equipment to determine a radio link control (RLC) failure configuration based on a configuration of allowed cells of at least one logical channel.

[0056] According to some embodiments, the RLC failure configuration includes a first threshold, and when executed by the at least one processor, the instructions further cause the user equipment to determine whether to transmit an RLC failure to the network based on the first threshold.

[0057] In some embodiments, the first threshold is a number of predetermined RLC retransmissions.

[0058] According to some embodiments, the RLC failure configuration includes first control information that indicates to the user equipment whether to disable at least one mapping restriction, and when executed by the at least one processor, the instructions further cause the user equipment to disable at least one mapping restriction based on the first control information.

[0059] According to some embodiments, the RLC failure configuration includes at least one priority threshold, wherein when the instruction is executed by at least one processor, it further causes the user equipment to determine whether to transmit an RLC failure to the network based on the at least one priority threshold and optionally at least one of the following: a) the lowest priority of the logical channels associated with the user equipment, b) the priority of the first logical channel.

[0060] According to some embodiments, when the instruction is executed by at least one processor, it further causes the user equipment to: determine whether a logical channel served by a first cell has reached a predetermined number of RLC retransmissions, and if the logical channel has reached the predetermined number of RLC retransmissions, transmit an RLC failure to the network of the logical channel if at least one other logical channel served by the first cell has not reached the predetermined number of RLC retransmissions.

[0061] According to some embodiments, the predetermined number of RLC retransmissions may be a configured first threshold or the maximum number of RLC retransmissions.

[0062] According to some embodiments, when the instruction is executed by at least one processor, it further causes the user equipment to: determine whether it can reselect another cell with a radio channel quality better than a first quality threshold, and if it can reselect another cell with a radio channel quality better than the first quality threshold, re - establish a Radio Resource Control (RRC) connection with the other cell based on the RLC failure configuration, and if it cannot reselect another cell with a radio channel quality better than the first quality threshold, determine whether to send an RLC failure report to the current serving cell based on the RLC failure configuration.

[0063] According to some embodiments, the upper layer of the UE may be configured by, for example, a device and / or the network to take different actions after receiving a report of an RLC failure from the RLC entity: According to some embodiments, the upper layer may analyze the services affected due to the RLC failure (i.e., the service(s) having data to be transmitted in the logical channel in which the RLC failure is detected).

[0064] According to some embodiments, the upper layer of the UE may check whether certain services / applications are no longer supported, e.g., due to an RLC failure of a first LCH. According to some embodiments, if a service has strict QoS requirements, it may need to be stopped because the LCH that detected the RLC failure is unavailable. In such a case, according to some embodiments, if the service uses multiple LCHs and some of these LCHs are used only by that service, the RLC failure message may also include information / suggestions to suspend the LCH / RBs that are used only by the affected service. This can ensure that only the LCHs serving the affected service will be suspended. According to some embodiments, after its suspension, the LCH will not be used in subsequent transmissions until it is restored and / or reconfigured.

[0065] According to some embodiments, if the affected service can adjust itself to tolerate performance degradation, the UE may indicate this in the RLC failure report, e.g., by including a corresponding indication in the RLC failure report. According to some embodiments, this indication may provide flexibility for the NW to decide whether to reconfigure the affected LCH / DRB or suspend it. According to some embodiments, an indication of the (multiple) LCHs serving only the affected service may be included again in the RLC failure report, such that the NW can make a decision with better knowledge.

[0066] Some embodiments relate to a method of operating an apparatus for a wireless communication system, including: configuring a radio link control (RLC) failure configuration for a user equipment, the RLC failure configuration defining how the user equipment should react to an RLC failure of a first logical channel associated with the user equipment.

[0067] Some embodiments relate to a method of operating a user equipment, including: determining a radio link control (RLC) failure configuration, the RLC failure configuration defining how the user equipment should react to an RLC failure of a first logical channel associated with the user equipment.

[0068] Although some expositions and embodiments use the radio interface between the UE and the network (e.g., gNB), according to some embodiments, the basic principles can also be applied to other communication and / or radio interfaces, e.g., to handle RLC failures of side-link (SL) RLC entities that can be applied to side-link communication between two user equipments (e.g., UEs), e.g., under a PC5-RRC connection.

[0069] For example, according to some embodiments, SL LCH transmissions between two SL UEs may be via multiple SL carriers or two resource pools, and thus, the proposed solutions for multi-cell scenarios according to some embodiments can be applied by considering SL transmissions via multiple SL carriers or multiple SL resource pools.

[0070] In other embodiments, the methods of some embodiments depicted for a single cell scenario can be applied to transmit SL LCH between two SL UEs via a single SL carrier or a single SL resource pool. Applying the proposed scheme in SL communication according to some embodiments can have similar advantages as described in some embodiments for communication between a UE and a network, such as to avoid PC5-RLC announcements and to allow services to continue to be available for other SL RLC entities / LCHs, even though an SL RLC failure is affecting one SL RLC entity / LCH.

[0071] According to some embodiments, it should be noted that in the case of sidelink communication, depending on the SL transmission mode and / or the UE RRC state, the (re)configuration of the SL RB / RLC entity / LCH of the UE can be performed by the SL UE itself or by the network. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Some exemplary embodiments will now be described with reference to the accompanying drawings, in which:

[0073] Figure 1 A simplified block diagram of an apparatus according to some embodiments is schematically depicted,

[0074] Figure 2 A simplified block diagram of a user equipment according to some embodiments is schematically depicted,

[0075] Figure 3 A simplified block diagram of a communication system according to some embodiments is schematically depicted,

[0076] Figure 4 A simplified flowchart of a method according to some embodiments is schematically depicted,

[0077] Figure 5 A simplified block diagram of an RLC failure configuration according to some embodiments is schematically depicted, and

[0078] Figure 6 and 7 Flowcharts 8, 9, 10 respectively schematically depict simplified flowcharts of methods according to some embodiments. DETAILED DESCRIPTION

[0079] Some embodiments relate to an apparatus for a wireless communication system. Figure 1 A simplified block diagram of an apparatus 100 according to some embodiments is schematically depicted, and Figure 4 A simplified flowchart of a method of operating the apparatus according to some embodiments is schematically described. Apparatus 100 ( Figure 1)Comprising at least one processor 102 and a memory 104 storing instructions 106 which, when executed by the at least one processor 102, cause the apparatus 100 to configure at least the user equipment 300 (see Figure 4 ) a Radio Link Control (RLC) fault configuration RLC-FCFG which defines how the user equipment should react to an RLC fault of a first logical channel associated with the user equipment.

[0080] According to some embodiments, some RLC fault configurations at the user equipment may also be specified in a standard, such as in 3GPP technical specifications, etc., and / or may be provided by the UE implementation.

[0081] In some embodiments, after configuring the RLC fault configuration RLC-FCFG for the user equipment 300, the apparatus 100 may receive an RLC fault from the user equipment, see Figure 4 step 302, for example in the form of at least one RLC fault report RLC-FR.

[0082] In some embodiments, the apparatus 100 ( Figure 1 ) may include a transceiver 108 for exchanging (i.e., transmitting and / or receiving) radio frequency (RF) signals with other components, such as for example a user equipment UE 200, see Figure 2 ) and / or other devices (not shown).

[0083] Figure 3 Schematically depicts a simplified block diagram of a communication system 10 according to some embodiments. For example, the communication system 10 may include an apparatus 100. The communication system 10 may also include at least one user equipment UE 200. The reference numeral 200' represents an optional other UE.

[0084] In some embodiments, the apparatus 100 or its functionality may be provided respectively in a network element of the communication system 10, such as in a base station 110 (e.g., a gNodeB (gNB) 110).

[0085] In some embodiments, the apparatus 100 according to the embodiments or its functionality may be respectively used for a wireless communication system 10 or within a wireless communication system 10 which is based on or at least partially adheres to the 3rd Generation Partnership Project (3GPP) radio standard, such as 4G E-UTRAN or 5G NR (5th Generation New Radio). In some embodiments, the apparatus 100 according to the embodiments or its functionality may be respectively used for a radio link failure (RLF) process of a 5G NR-based communication system 10.

[0086] In some embodiments, the UE 200 (also see Figure 2) may include at least one processor 202 and a memory 204 storing instructions, for example, in the form of computer program code 206.

[0087] Optionally, according to other exemplary embodiments, the UE 200 may include a transceiver 208 for exchanging (i.e., transmitting and / or receiving) radio frequency (RF) signals with other components (such as, for example, the device 100 or the gNB 110 ( Figure 3 )) and / or other devices (not shown).

[0088] As an example, one trigger condition for RLF in the Uu interface currently defined for 5G NR, for example, is characterized as follows: after using the RLC acknowledged mode (AM), the number of maximum RLC retransmissions is indicated to have been reached from the radio link control (RLC) layer. According to this trigger condition, the number of maximum retransmissions in the RLC is configured by using the parameter "maxRetxThreshold", which is configured in the information element (IE) "RLC-Config" according to 3GPP TS 38.331 (see, for example, 3GPP TS 38.331 V15.8.0 (2019-12)) and is used by the transmission side of the AM RLC entity to limit the total number of retransmissions of the RLC protocol data unit (PDU).

[0089] The number of maximum retransmissions parameter currently defined for 5G NR, for example (i.e., maxRetxThreshold configured in RLC-Config), is applied to the RLC AM defined in 3GPP TS 38.331, where the value t1 corresponds to 1 retransmission, the value t2 corresponds to 2 retransmissions, and so on. If the number of maximum retransmissions of the RLC entity is reached in an exemplary single-cell scenario, RLF will be declared, which will trigger the UE to re-establish the RRC connection with the NW, as described above. More specifically, when RLF is declared, all radio bearers (RBs) except SRB0 will be suspended. After the RRC connection re-establishment procedure is successfully completed, after receiving the first RRCReconfiguration message, these suspended RBs (i.e., SRB2 and DRB) can be resumed first. Therefore, during the resumption of the DRB, user plane data cannot be transmitted, resulting in an undesirable interruption in the running application.

[0090] According to TS 38.331, RLC-Config is included in the IE RLC-BearerConfig, which is used to configure the RLC entity and the corresponding logical channel (LCH) in the MAC for the uplink (except for the link with the PDCP entity). Thus, different RLC entities can be configured for the UE 200 (e.g., for different logical channels), and these entities can be configured in different ways, e.g., having different values for the maximum number of retransmissions.

[0091] In the current definition of RLF, which is currently defined for example for 5G NR, an RLC failure of a logical channel / RLC entity (e.g., when the maxRetxThreshold is reached) means the declaration of RLF, which in turn means the suspension of all DRBs, which will interrupt the data transmission on any other DRB.

[0092] As an example, first, when an RLC failure occurs, it may be due to radio conditions and / or protocol problems. In the case of radio problems, this means that even RLC retransmissions cannot help recover from radio losses. Although it can be expected that the radio link monitoring (RLM) process can generally detect radio problems before an RLC failure occurs, the current RLM procedures defined for example for 5G NR are limited to the primary cell (PCell). Thus, an RLC failure may occur due to radio problems or protocol failures (including configuration problems) on a secondary cell (SCell), rather than due to radio failures only on the PCell.

[0093] In addition, 5G NR also introduces restrictions on the "allowed cells" that an LCH can use, which is different from traditional LTE, because an RLC failure of an LCH may only be a problem for those allowed cells of that LCH (e.g., if they are unlicensed cells, high-frequency cells, etc.), but should not affect other LCHs if they use different cells with higher reliability / better channel quality.

[0094] This means that according to some embodiments, an RLC failure of one RLC entity may not mean that another logical channel cannot be adequately supported. This is an aspect that may be particularly relevant when different service types with different quality of service (QoS) requirements coexist in a device. For example, achieving the maxRetxThreshold value from a logical channel for ultra-reliable and low-latency communication (URLLC) services does not necessarily trigger the suspension of a logical channel with more relaxed QoS requirements, such as a logical channel for supporting massive machine type communication (mMTC) and / or enhanced mobile broadband (eMBB) services.

[0095] As another example, second, re - establishment triggered due to an RLC failure may be a relatively slow procedure as it may include cell selection (of either the old or new cell), a random access procedure to the selected cell, and several RRC messages to be exchanged. If the RLC failure is due to a protocol / configuration issue, a recovery attempt in the same cell (e.g., by re - configuring the affected RLC entity) may succeed. However, this can only be initiated after an unnecessary delay due to the re - establishment.

[0096] Based on this, some embodiments address aspects such as, for example, a method for handling RLC failures, which aims to recover the affected RLC entity (i.e., the RLC entity that detected the (multiple) RLC failures) more quickly, while they can allow the unaffected RLC entities to continue their services.

[0097] According to some embodiments, as already mentioned above, the user equipment 200 ( Figure 3 ) can use, for example, an RLC failure configuration RLC_FCFG provided by being configured via the apparatus 100 according to some embodiments to determine how to react to such an RLC failure. Figure 4 ) to determine how to react to such an RLC failure.

[0098] According to some embodiments, the RLC failure configuration RLC_FCFG defines whether the user equipment 200 should notify the network (e.g., the apparatus 100 or the gNB 110) of an RLC failure of the first logical channel.

[0099] According to some embodiments, the RLC failure configuration defines whether the user equipment 200 should notify the network of an RLC failure of the first logical channel when at least a second logical channel associated with the user equipment 200 is operating normally (i.e., not experiencing an RLC failure). According to some embodiments, this can enable at least a second LCH and / or RB associated therewith to remain normal (i.e., uninterrupted) operation, for example instead of declaring an RLF and initiating a re - establishment.

[0100] As an example, for instance, when the second logical channel has not reached a predetermined number of RLC re - transmissions (e.g., a first threshold or the maximum number of RLC re - transmissions), the second logical channel associated with the user equipment is operating normally.

[0101] According to some embodiments, the UE 200 may be configured with multiple LCHs and / or RLC entities.

[0102] According to some embodiments, the UE 200 may be configured with a separate RLC failure configuration RLC_FCFG for each UE or for each LCH. In the case of each LCH RLC failure configuration RLC_FCFG, it enables the provision of different LCHs with different RLC failure configurations.

[0103] According to some embodiments, when executed by at least one processor 102, the instructions 106( Figure 1 ) also cause the apparatus 100 to explicitly configure the RLC failure configuration RLC_FCFG for the user equipment 200. According to some embodiments, the RLC failure configuration RLC_FCFG may be explicitly provided to the UE 200, for example, together with other information transmitted from the apparatus 100 to the UE 200, such as, for example, the configuration of the RLC entity of the UE 200.

[0104] According to some embodiments, the user equipment 200 may also be implicitly configured with the RLC failure configuration RLC_FCFG.

[0105] According to some embodiments (e.g., which may be based on a multi-cell carrier aggregation (CA) / dual connectivity (DC) scenario), for each LCH that configures whether an RLC failure of the LCH should trigger an RLC failure report instead of re-establishment may be implicitly done, for example, based on the allowed cell configuration of the LCH.

[0106] According to some embodiments, the implicit configuration may be part of the allowed cell configuration and may be enabled / disabled for each UE 200, 200'( Figure 3 ). For example, the configured cells allowed for the failed LCH (i.e., the first LCH) may be considered failed and thus may be suspended / deactivated as long as at least another cell is not failed and is mapped to at least another LCH: under these conditions, according to some embodiments, an RLC failure report may be triggered without (RRC) re-establishment. According to some embodiments, otherwise, for example, if any other cell also fails or no other non-failed LCH is mapped to the cell, an RRC re-establishment is initiated.

[0107] In some embodiments, the allowed cells are unlicensed cells and / or high-frequency cells (e.g., using, for example, the frequency range FR2 defined in 3GPP 38.101-1, see, for example, 3GPP TS 38.101-1 V16.2.0 (2019-12), Table 5.1-1), because these may be more prone to radio errors. This ensures that if they use different cells with higher reliability / better channel quality, problems on these cells do not affect other LCHs.

[0108] In some embodiments, referring to Figure 5 , the RLC failure configuration RLC_FCFG includes a first threshold T1, where the user equipment 200 may determine whether to transmit an RLC failure to the network (e.g., gNB 110) based on the first threshold.

[0109] In some embodiments, the first threshold T1 is the number of predetermined RLC retransmissions.

[0110] According to some embodiments (e.g., which may be based on a single-cell scenario or a multi-cell CA / DC scenario), in view of the existing threshold parameter “maxRetxThreshold”, the first threshold T1 may be regarded as a new (additional) threshold, and the existing threshold parameter “maxRetxThreshold” is configured in the information element (IE) “RLC Config” according to 3GPP TS 38.331 (see, for example, 3GPP TS 38.331 V15.8.0 (2019-12)).

[0111] According to some embodiments, the first (i.e., new) threshold T1 may be expressed as, for example, “maxRetxThreshold_RLCReport” and may be configured for the UE 200 to determine a) when (and / or whether) to report an RLC failure of the first LCH, e.g., if the number of current RLC AM retransmissions reaches the first threshold, and / or b) when (whether) to declare an RLF (e.g., if the number of current RLC AM retransmissions reaches the existing threshold parameter “maxRetxThreshold” defined for RLF detection).

[0112] According to some embodiments, the value of the first threshold T1 “maxRetxThreshold_RLCReport” may be set to be lower than the existing “maxRet_threshold”, e.g., to trigger the report for the first time. According to some embodiments, this enables an attempt to first recover / resolve the RLC failure problem, e.g., by reconfiguring the protocol parameters of the affected (first) LCH or changing the allowed cells and / or other LCP restrictions before declaring an RLF and suspending all DRBs.

[0113] According to some embodiments, the RLC failure configuration RLC_FCFG( Figure 5 ) includes first control information CI1, and the first control information CI1 indicates to the user equipment 200 whether to disable at least one mapping restriction.

[0114] According to some embodiments (e.g., which can be based on a single-cell scenario or a multi-cell CA / DC scenario), when it is detected that an RLC entity / LCH reaches a given number of RLC AM retransmissions (e.g., corresponding to the maximum number defined for RLF detection (e.g., the existing "maxRetxThreshold") or a lower configured number, e.g., the first threshold according to some embodiments explained above), if the LCH is configured with LCP (Logical Channel Prioritization) mapping restrictions (e.g., according to allowedCG_list, allowedPriorityLevels, and allowedServingCells, see, e.g., 3GPP TS 38.300 V15.8.0 (2019-12), e.g., chapter 16.1.2), then the UE 200( Figure 3 ) can disable at least one of these mapping restrictions (e.g., instead of triggering RLF), which may be beneficial for obtaining the data to be transmitted as soon as possible, and according to some embodiments, this can be exemplarily referred to as some actions of "recovery behavior".

[0115] According to some embodiments, the disabling of at least one of these mapping restrictions can be automatically performed, i.e., without an explicit instruction received by the UE 200.

[0116] According to some embodiments, enabling this "recovery behavior" may depend on the network configuration. The configuration (e.g., according to some embodiments explained above, in addition to the possible first threshold T1) can indicate which LCP mapping restriction is to be disabled (e.g., via the information element (IE) "RestrictionsDisableList"). For example, according to some embodiments, after disabling the restriction according to "allowedServingCells", the UE 200 can fill the UL grant applicable to the cell previously restricted for the affected (e.g., first) LCH with data from that LCH. According to some embodiments, in turn, the presence of data of that LCH in the transmission corresponding to that grant may implicitly indicate to the network that the UE 200 has disabled (LCP mapping) restrictions, and in turn, according to some embodiments explained above, the UE 200 has experienced an RLC failure or the UE has reached the first threshold.

[0117] According to some embodiments, the first control information CI1 indicates which mapping restriction among a plurality of mapping restrictions is to be disabled.

[0118] According to some embodiments, the RLC failure configuration RLC_FCFG( Figure 5 ) includes at least one priority threshold P1, P2, where the user equipment 200 can determine whether to transmit an RLC failure to the network based on at least one priority threshold P1, P2.

[0119] According to some embodiments, the user equipment 200 may determine whether to transmit an RLC failure to the network based on at least one of the priority thresholds P1, P2, and at least one of the following: a) the lowest priority of the logical channels associated with the user equipment 200, b) the priority of the first logical channel.

[0120] According to some embodiments, the first priority threshold P1 and the second priority threshold P2 may be provided, for example, by the network or through pre-configuration.

[0121] According to some embodiments (e.g., which may be based on a single-cell scenario or a multi-cell CA / DC scenario), if the lowest priority of any existing logical channel is lower than the first configured threshold P1, and the priority of the LCH on which the RLC failure is detected is higher than the second threshold P2, then the UE 200 may send an RLC failure report RLC_FR to the NW 10 or the apparatus 100. Figure 4 ) According to some embodiments, if another LCH having a certain (i.e., non-vanishing) QoS difference and / or configuration difference compared to the LCH on which the RLC failure is detected is configured, the RLC failure of the affected LCH (i.e., one LCH on which the RLC failure is detected) does not necessarily imply a failure of the other LCHs, and thus, the other LCHs should not be affected. Alternatively, according to some embodiments, if a failure occurs in an LCH whose priority is higher than or lower than the configured threshold, then for each LCH or priority threshold configuration, an RLC failure report RLC_FR is triggered.

[0122] According to some embodiments, when executed by at least one processor 102, the instructions 106 ( Figure 1 ) also cause the apparatus 100 to configure 300 second control information CI2 (e.g., a flag) for the user equipment 200 (e.g., an LCH / RLC entity), where the second control message CI2 indicates at least one of the following: a) after detecting an RLC failure of the first logical channel, the user equipment 200 should declare a radio link failure, b) the user equipment 200 should transmit an RLC failure of the first logical channel to the network, e.g., in the form of an RLC failure report RLC_FR, c) after detecting an RLC failure of at least one other logical channel other than the first logical channel, the user equipment 200 should declare a radio link failure (RLF), d) after detecting an RLC failure of at least one other logical channel other than the first logical channel, the user equipment 200 should transmit an RLC failure report.

[0123] According to some embodiments, the second control information CI2 (e.g., a flag) may be set taking into account the QoS requirements of the LCH / RLC entity and / or the set of configured LCH / RGC entities.

[0124] According to some embodiments, when the instruction 106 is executed by at least one processor 102, it further causes the device 100 to set at least a part of the RLC failure configuration RLC_FCFG based on at least one user equipment specific condition.

[0125] According to some embodiments, the value of the first threshold T1 and / or the conditions for declaring a radio link failure and / or sending an RLF failure report can be set considering UE specific conditions (such as the existing services in the UE 200 and optional QoS requirements). For example, if both eMBB services and URLLC services coexist according to some embodiments, an RLC failure from only the URLLC service may not declare an RLF.

[0126] According to some embodiments, the first threshold and the second threshold can be configured, and if the highest value of the current number of maximum retransmissions parameter (i.e., "maxRetxThreshold" configured in the RLC-Config) defined by 5G NR for an existing logical channel is higher than the first configured threshold, and the "maxRetxThreshold" value of the LCH for which an RLC failure is detected is lower than the second configured threshold, then the UE 200 can send an RLC failure report to the NW. In this option, the UE 200 can ensure that there is a significant difference in maxRetxThreshold between the declared LCH (the LCH declaring an RLF) and other LCHs. Therefore, the RLC failure of the affected RLC entity should not affect the operation of another LCH.

[0127] According to some embodiments, when the instruction 106 is executed by at least one processor 102, it further causes the device 100 to broadcast at least a part of the RLC failure configuration RLC_FCFG ( Figure 3 ) such as at least one of the following: the first threshold, the second threshold.

[0128] According to some embodiments, the device 100 or the network can broadcast at least a part of the RLC failure configuration in a system information block (SIB), such as at least one of the following: the first threshold, the second threshold.

[0129] Other embodiments relate to a UE 200 ( Figure 2 ) that includes a processor 202 and a memory 204 storing instructions 206, which when executed by at least one processor 202, cause the user equipment 200 to at least (also see the flowchart of Figure 6 ) determine 350 a radio link control RLC failure configuration RLC-FCFG that defines how the user equipment 200 should react to an RLC failure of a first logical channel associated with the user equipment 200.

[0130] According to some embodiments, determining the 350 RLC failure configuration RLF_FCFG may include at least one of the following: receiving (e.g., for embodiments with explicit configuration) the RLC failure configuration RLC_FCFG from a device (e.g., device 100 according to an embodiment) and / or the gNB 110, determining the RLC failure configuration RLC_FCFG through other data and / or configuration (e.g., for embodiments with implicit configuration).

[0131] According to some embodiments, at least some of the RLC failure configurations at the user equipment may also be specified in a standard, e.g., specified in 3GPP technical specifications, and / or may be provided by UE implementations.

[0132] According to some embodiments, when executed by at least one processor 202, the instruction 206 also causes the user equipment 200 to determine 352, e.g., whether the user equipment 200 should notify the network of an RLC failure of a first logical channel when at least a second logical channel associated with the user equipment 200 is operating normally, based on the RLC failure configuration RLC_FCFG.

[0133] According to some embodiments, when executed by at least one processor 202, the instruction 206 also causes the user equipment 200 to determine 360 ( Figure 7 ) the RLC failure configuration RLC_FCFG based on the configuration of the allowed cells of at least one logical channel.

[0134] According to some embodiments, the RLC failure configuration includes a first threshold T1, where when executed by at least one processor 202, the instruction 206 also causes the user equipment 200 to determine 362 ( Figure 7 ) whether to transmit an RLC failure to the network based on the first threshold T1.

[0135] According to some embodiments, the RLC failure configuration includes first control information CI1 that indicates to the user equipment 200 whether to disable at least one mapping restriction, where when executed by at least one processor 202, the instruction 206 also causes the user equipment 200 to disable 364 ( Figure 7 ) at least one mapping restriction based on the first control information.

[0136] According to some embodiments, the RLC failure configuration RLC_FCFG includes at least one priority threshold P1, P2, where when executed by at least one processor 202, the instruction 206 also causes the user equipment 202 to determine whether to transmit an RLC failure to the network based on at least one priority threshold and optionally at least one of the following: a) the lowest priority of the logical channels associated with the user equipment, b) the priority of the first logical channel.

[0137] According to some embodiments, when the instruction 206 is executed by at least one processor 202, it further causes the user equipment 200 to: determine whether a logical channel served by a first cell has reached a predetermined number of RLC retransmissions, and, if the logical channel has reached the predetermined number of RLC retransmissions, transmit an RLC failure to the network for the logical channel in the case where at least one other logical channel served by the first cell has not reached the predetermined number of RLC retransmissions.

[0138] According to some embodiments, when the instruction 206 is executed by at least one processor 202, it further causes the user equipment 200 to: determine whether it can reselect another cell having a radio channel quality better than a first quality threshold, and, if it can reselect another cell having a radio channel quality better than the first quality threshold, re - establish a radio resource control (RRC) connection with the other cell based on an RLC failure configuration, and, if it cannot reselect another cell having a radio channel quality better than the first quality threshold, determine whether to send an RLC failure report to the current serving cell based on the RLC failure configuration.

[0139] According to some embodiments, the upper layer of the UE may be configured by, for example, the apparatus 100 and / or the network or the gNB 110 to take different actions after receiving a report of an RLC failure from the RLC entity: According to some embodiments, the upper layer may analyze the service(s) affected by the RLC failure (i.e., the service(s) having data to be transmitted in the logical channel in which the RLC failure is detected).

[0140] According to some embodiments, the upper layer of the UE 200 may check whether certain service(s) / application(s) are no longer supported, e.g., due to an RLC failure of a first LCH. According to some embodiments, if a service has strict QoS requirements, it may need to be stopped because the LCH in which the RLC failure is detected is unavailable. In this case, according to some embodiments, if the service uses multiple LCHs and some of these LCHs are used only by the service, the RLC failure message may also contain information / suggestions to suspend the LCH / RBs used only by the affected service. This can ensure that only the LCHs serving the affected service will be suspended. According to some embodiments, after its suspension, the LCH will not be used in subsequent transmissions until it is restored and / or re - configured.

[0141] According to some embodiments, if the affected service can adjust itself to tolerate performance degradation, the UE 200 may report the RLC failure as RLC_FR ( Figure 3) indicate this, for example, by including a corresponding indication in the RLC fault report RLC_FR. According to some embodiments, this indication may provide flexibility to the NW to decide whether to reconfigure the affected LCH / DRB or suspend it. According to some embodiments, the indication for only the (multiple) LCHs serving the affected service may be included again in the RLC fault report, so that the NW can make a decision with better knowledge.

[0142] Figure 8 Schematically depicts a simplified flowchart of a method according to some embodiments. In step 400, the UE 200 ( Figure 3 ) may be configured with multiple LCH / RLC entities and an RLC fault configuration RLC-FCFG, such as an RLC fault configuration RLC-FCFM for each LCH. In step 401, the UE 200 determines whether an RLC fault of an LCH (i.e., one LCH among the multiple LCHs configured in step 400) is detected. If not, the method returns to step 401. If an RLC fault of the LCH (i.e., the first LCH) is detected, the method proceeds to step 402, where the RLC entity affected by the RLC fault sends an indication to the RRC layer of the UE. In step 403, it is determined by the UE 200 based on the RLC fault configuration RLC-FCFG whether to trigger an RLC fault report. If it is determined in step 403 to trigger an RLC fault report, the method proceeds to step 404, where the UE 200 may send the RLC fault report RLC-FR ( Figure 4 ) to the network (such as the device 100 and / or the gNB 110) and / or, according to some embodiments, if configured, disable at least one mapping restriction, such as disabling the allowed cell restriction of the affected LCH.

[0143] If it is determined in step 403 not to trigger an RLC fault report, the method proceeds to step 405, where it is determined whether an RLF statement is triggered. If so, the method proceeds to step 406, where the UE 200 initiates an RRC re-establishment procedure. If not, the method proceeds to step 401. In some embodiments, advantageously, the RRC re-establishment procedure (see Figure 8 step 406) can be avoided. Instead, step 404 can be executed.

[0144] Figure 9 Schematically depicts a simplified flowchart of a method according to some embodiments. Note that for simplicity, user plane transmission is not shown. The reference numeral 410 symbolizes the configuration RLC-Config of one or more RLC entities of the UE 200. According to some embodiments, the configuration 410 may also include an RLC fault configuration RLC-FCFG according to some embodiments (also see Figure 3), for example, including the first threshold T1 explained above for UL-AM-RLC (see also Figure 5 ) and / or the "RestrictionsDisableList" IE. The reference numeral 411 symbolizes the LCP restriction configuration, for example, characterizing the LCP mapping restrictions according to allowedCG_list, allowedPriorityLevels, and allowedServingCells, see, for example, 3GPP TS 38.300 V15.8.0 (2019-12), for example, Chapter 16.1.2. Block 412 indicates the radio link monitoring (RLM) steps performed by the UE 200, and block 413 indicates the configuration trigger for detecting the RLC fault report, and according to some embodiments, disabling the previously configured LCP restriction(s), see reference numeral 411. Arrow 414 indicates the transmission of the RLC fault information to the gNB 110, and block 415 characterizes the network action performed after receiving (e.g., based on) the RLC fault information. According to some embodiments, the network action 415 may include reconfiguration. Thus, arrow 416 may represent a reconfiguration message to the UE 200, such as RRCReconfiguration, which may, for example, include the (new) RLC configuration. Block 417 indicates that the UE reconfigures the LCH affected by the RLC fault, and according to some embodiments, may also include enabling the previously disabled (see block 413) LCP restriction. Alternatively, the UE may enable the LCP restriction in block 417 based on the reconfiguration message received in 416.

[0145] Figure 10 A simplified flowchart of a method according to some embodiments is schematically depicted. Note that, similar to Figure 7 , for simplicity, the user plane transmission is not shown. Similar to Figure 9 the arrow 410, Figure 10 the reference numeral 420 symbolizes the configured RLC-Config of one or more RLC entities of the UE 200. According to some embodiments, the configuration 420 may also include the RLC fault configuration RLC-FCFG according to some embodiments (see also Figure 3 ), for example, including the first threshold T1 explained above for UL-AM-RLC (see also Figure 5 ) and / or the "RestrictionsDisableList" IE. The reference numeral 421 symbolizes the LCP restriction configuration, for example, characterizing the LCP mapping restrictions according to allowedCG_list, allowedPriorityLevels, and allowedServingCells, as mentioned above. Similar to Figure 9 the blocks 412, 413, Figure 10The boxes 422, 423 indicate the following steps: radio link monitoring (RLM) performed by the UE 200 (box 422) and detection of the triggering of the RLC fault report configuration, and according to some embodiments, disabling of previously configured LCP restriction(s), see reference numeral 421 (box 423).

[0146] According to some embodiments, once the network receives detection from the uplink that the UE 200 has disabled the LCP restriction(s), the RLC fault information can also be implicitly indicated to the network.

[0147] According to some embodiments, one or more of the following network actions can be performed, such as traditional network actions, which can be triggered by receiving an RLC fault indication (see, for example Figure 9 arrow 414). According to some embodiments, network actions may occur to attempt to restore the service of the LCH / RB affected by the RLC fault:

[0148] - The NW may decide to suspend the affected DRB(s), while continuing to provide other services to the UE 200.

[0149] - The NW may decide to suspend the affected LCH entity, but continue the service of the affected RB / LCH by mapping the traffic of the affected DRB / LCH to an unaffected LCH entity.

[0150] - The NW may reconfigure the affected DRB / LCH such that the affected service(s) can still be continuously served.

[0151] - Compared to the DRB / LCH declaring the RLC fault, the NW may proactively reconfigure other DRB / LCHs with similar or more stringent QoS requirements. According to some embodiments, proactive reconfiguration, for example by increasing the parameter "maxRetxThreshold", can help achieve better service continuity for the DRB / LCH under consideration by potentially avoiding future RLC faults affecting other RBs.

[0152] - Alternatively, for example, the NW may decide to trigger a change of the serving cell or serving bandwidth. For example, if the NW receives multiple RLC fault reports from the same or different RLC entity(ies), the NW may decide to trigger deactivation of the serving cell, reconfiguration of the serving beam, BWP (bandwidth part) switching or handover, etc.

[0153] According to some embodiments, the RB / LCH affected by the RLC fault is not reconfigured repeatedly ("no-repeat scenario").

[0154] According to some embodiments, a failure of an LCH / RB operating on a cell may not cause the suspension of the entire cell operation, but only the suspension of the affected LCH.

[0155] According to some embodiments, although an RLC failure is affecting one RB, one or more services may continue for other RBs, and in the meantime, the network may, for example, resolve the issues related to the RLC failure of the affected RB as quickly as possible, thereby shortening the recovery time. According to some embodiments, during the recovery attempt, the affected RLC / LCH (failure) may use any non-suspended cell to serve, and even if initially that cell is not allowed (i.e., according to some embodiments, the LCP mapping restriction is disabled during an RLC failure), these cells are not suspended.

[0156] In other words, compared with conventional methods (such as triggering RLF and RRC re-establishment), some embodiments do not introduce additional delays when resolving an RLC failure affecting an RB because in most scenarios, the RLC failure report should be received by the network at the same time as or before the RLF report.

[0157] Although some expositions and embodiments use the radio interface between a UE and a network (such as a gNB), according to some embodiments, the basic principles can also be applied to other communication and / or radio interfaces, for example, to handle the RLC failure of a side-link (SL) RLC entity that can be used for side-link communication between two user devices (such as UEs), for example, under a PC5-RRC connection.

[0158] For example, according to some embodiments, the SL LCH transmission between two SL UEs can be performed via multiple SL carriers or two resource pools, and thus, the proposed solutions for multi-cell scenarios according to some embodiments can be applied by considering SL transmissions via multiple SL carriers or multiple SL resource pools.

[0159] In other embodiments, the methods of some embodiments depicted for single-cell scenarios can be applied to the transmission of SL LCH between two SL UEs via a single SL carrier or a single SL resource pool. Applying the proposed solution in SL communication can have similar advantages as described in some embodiments with reference to the communication between a UE and a network, such as avoiding PC5-RLC declarations and allowing services to continue for other SL RLC entities / LCHs, although an SL RLC failure is affecting one SL RLC entity / LCH.

[0160] According to some embodiments, it should be noted that in the case of side-link communication, depending on the SL transmission mode and / or the UE RRC state, the (re)configuration of the SL RB / RLC entity / LCH of the UE can be performed by the SL UE itself or the network.

[0161] Even though some embodiments have been described above by way of example with reference to the drawings, it is obvious that the embodiments are not limited thereto, but can be modified in several ways within the scope of the appended claims. Accordingly, all words and expressions should be interpreted broadly, and they are intended to illustrate rather than limit the embodiments. It will be obvious to those skilled in the art that when technological progress occurs, the concepts according to the embodiments can be implemented in various ways. Further, it is obvious to those skilled in the art that the described embodiments can, but do not require to, be combined with other embodiments in various ways.

Claims

1. An apparatus (100) for a wireless communication system (10), comprising at least one processor (102) and a memory (104) storing instructions, wherein when the instructions are executed by the at least one processor (102), the apparatus (100) configures (300) at least a radio link control (RLC) failure configuration (RLC-FCFG) for a user equipment (200), the RLC-FCFG defining how the user equipment (200) should react to an RLC failure of a first logical channel associated with the user equipment (200), wherein the RLC failure configuration (RLC-FCFG) comprises at least one priority threshold (P1, P2), and wherein the user equipment (200) is configured to determine whether to transmit the RLC failure to a network based on the at least one priority threshold (P1, P2) and at least one of: a) a lowest priority of a logical channel associated with the user equipment, or b) a priority of the first logical channel.

2. The apparatus (100) according to claim 1, wherein the RLC failure configuration (RLC-FCFG) defines whether the user equipment (200) should notify the network (10) of the RLC failure of the first logical channel.

3. The apparatus (100) according to claim 1, wherein the RLC failure configuration (RLC-FCFG) defines whether the user equipment (200) should notify the network (10) of the RLC failure of the first logical channel when at least a second logical channel associated with the user equipment (200) is operating normally.

4. The apparatus (100) of claim 1, wherein the instructions, when executed by the at least one processor (102), further cause the apparatus (100) to explicitly configure the RLC failure configuration (RLC-FCFG) for the user equipment (200).

5. The apparatus (100) according to claim 1, wherein the RLC failure configuration (RLC-FCFG) comprises a first threshold (T1), wherein the user equipment (200) can determine whether to transmit the RLC failure to a network based on the first threshold (T1).

6. The apparatus (100) according to claim 1, wherein the RLC failure configuration (RLC-FCFG) comprises: First control information (CI1) indicating to the user equipment (200) whether to disable at least one mapping restriction.

7. The apparatus (100) according to claim 6, wherein the first control information (CI1) indicates which mapping restriction of a plurality of mapping restrictions is to be disabled.

8. The apparatus (100) according to claim 1, wherein the instructions, when executed by the at least one processor (102), further cause the apparatus (100) to configure second control information (CI2) for the user equipment, the second control information (CI2) indicating at least one of the following: a) after detecting the RLC failure of the first logical channel, the user equipment should declare a radio link failure, b) the user equipment should transmit the RLC failure of the first logical channel to the network, c) after detecting the RLC failure of at least one other logical channel other than the first logical channel, the user equipment should declare a radio link failure, d) the user equipment should transmit the RLC failure of the at least one other logical channel to the network.

9. The apparatus (100) of claim 1, wherein the instructions, when executed by the at least one processor (102), further cause the apparatus (100) to set at least a portion of the RLC failure configuration (RLC-FCFG) based on at least one user equipment specific condition.

10. The apparatus (100) of any one of the preceding claims, wherein the instructions, when executed by the at least one processor (102), further cause the apparatus (100) to broadcast at least a portion of the RLC failure configuration (RLC-FCFG).

11. A user equipment (200) comprising at least one processor (202) and a memory (204) storing instructions (206), wherein the instructions (206) when executed by the at least one processor (202) cause the user equipment (200) to at least determine (350) a radio link control RLC failure configuration (RLC-FCFG), wherein the RLC-FCFG defines how the user equipment (200) should react to an RLC failure of a first logical channel associated with the user equipment (200), wherein the RLC failure configuration (RLC-FCFG) comprises at least one priority threshold (P1, P2), causing the user equipment (200) to determine whether to transmit the RLC failure to a network based on the at least one priority threshold (P1, P2) and at least one of: a) a lowest priority of a logical channel associated with the user equipment, or b) a priority of the first logical channel.

12. The user equipment (200) of claim 11, wherein the instructions, when executed by the at least one processor (202), further cause the user equipment (200) to determine (352) based on the RLC failure configuration (RLC-FCFG) whether the user equipment (200) should notify a network (10) of the RLC failure of the first logical channel.

13. The user equipment (200) of claim 11, wherein the instructions, when executed by the at least one processor (202), further cause the user equipment (200) to determine (352) based on the RLC failure configuration (RLC-FCFG) whether the user equipment (200) should notify a network (10) of the RLC failure of the first logical channel when at least a second logical channel associated with the user equipment (200) is operating normally.

14. The user equipment (200) of claim 11, wherein the instructions, when executed by the at least one processor (202), further cause the user equipment (200) to determine (360) the radio link control, RLC, failure configuration (RLC-FCFG) based on a configuration of allowed cells for at least one logical channel.

15. The user equipment (200) of claim 11, wherein the RLC failure configuration (RLC-FCFG) comprises a first threshold value (T1), wherein the instructions, when executed by the at least one processor (202), further cause the user equipment (200) to determine (362) whether to transmit the RLC failure to the network based on the first threshold value (T1).

16. The user equipment (200) according to claim 11, wherein the RLC failure configuration (RLC-FCFG) comprises first control information (CI1) indicating to the user equipment (200) whether to disable at least one mapping restriction, wherein the instructions, when executed by the at least one processor (202), further cause the user equipment (200) to disable (364) the at least one mapping restriction based on the first control information (CI1).

17. The user equipment (200) according to claim 11, wherein the instructions, when executed by the at least one processor (202), further cause the user equipment (200): to determine whether a logical channel served by a first cell has reached a predetermined number of RLC retransmissions, and, if the logical channel has reached the predetermined number of RLC retransmissions, to transmit the RLC failure to the network for the logical channel if at least one further logical channel served by the first cell has not reached the predetermined number of RLC retransmissions.

18. The user equipment according to any one of claims 11 to 17, wherein the instructions, when executed by the at least one processor (202), further cause the user equipment (200): to determine whether it can reselect another cell whose radio channel quality is better than a first quality threshold, and, if it can reselect another cell whose radio channel quality is better than the first quality threshold, to reestablish a radio resource control, RRC, connection with the other cell, and, if it cannot reselect another cell whose radio channel quality is better than the first quality threshold, to determine, based on the RLC failure configuration (RLC-FCFG), whether to send an RLC failure report to a current serving cell.

19. A method of operating an apparatus (100) for a wireless communication system (10), comprising: A radio link control RLC failure configuration (RLC-FCFG) is configured (300) for a user equipment (200), the RLC-FCFG defining how the user equipment (200) should react to an RLC failure of a first logical channel associated with the user equipment (200), wherein the RLC failure configuration (RLC-FCFG) comprises at least one priority threshold (P1, P2), the method comprising: determining whether to transmit the RLC failure to a network based on the at least one priority threshold (P1, P2) and at least one of: a) the lowest priority of the logical channels associated with the user equipment, or b) the priority of the first logical channel.

20. A method of operating a user device (200), comprising: determining (350) a radio link control RLC failure configuration (RLC-FCFG), the RLC-FCFG defining how the user equipment (200) should react to an RLC failure of a first logical channel associated with the user equipment (200); And wherein the RLC fault configuration (RLC-FCFG) includes at least one priority threshold (P1, P2), the method comprising: determining whether to transmit the RLC fault to the network based on the at least one priority threshold (P1, P2) and at least one of the following: a) the lowest priority of a logical channel associated with the user equipment, or b) the priority of the first logical channel.

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