Patent Description:
The disclosure further relates to a method of operating an apparatus for a wireless communications system.

Wireless communications systems may e.g. be used for wireless exchange of information between two or more entities.

The scope of protection sought for various embodiments of the disclosure is set out by the independent claims. The exemplary embodiments and features, if any, described in this specification, that do not fall under the scope of the independent claims, are to be interpreted as examples useful for understanding various exemplary embodiments of the disclosure.

Some embodiments relate to an apparatus for a wireless communications system, comprising at least one processor, and memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to configure a user equipment with a radio link control, RLC, failure configuration which defines how the user equipment should react to an RLC failure of a first logical channel associated with the user equipment, wherein the RLC failure configuration comprises at least one priority threshold (P1, P2), wherein the user equipment (<NUM>) is configured to determine, based on the at least one priority threshold (P1, P2) and on at least one of: a) a lowest priority of logical channels associated with the user equipment, b) a priority of the first logical channel, whether to transmit the RLC failure to a or the network.

In some embodiments, the apparatus or its functionality, respectively, may be provided in a network element of the communications systems, for example in a base station, e.g. a gNodeB (gNB).

In some embodiments, the apparatus according to the embodiments or its functionality, respectively, may be used for or within wireless communications systems based on or at least partially adhering to third generation partnership project, 3GPP, radio standards such as <NUM> E-UTRAN or <NUM> NR (fifth generation new radio). In some embodiments, the apparatus according to the embodiments or its functionality, respectively, may be used for a radio link failure (RLF), procedure of <NUM> NR-based communications systems.

As an example, one triggering condition for an RLF in a Uu interface as currently defined e.g. for <NUM> NR is characterized as follows: upon indication from a radio link control (RLC) layer that a maximum number of RLC retransmissions has been reached when using an RLC acknowledged mode (AM). According to this triggering condition, a maximal number of retransmissions in RLC is configured by using a parameter "maxRetxThreshold", which is configured in the information element (IE) "RLC-Config", as per 3GPP TS <NUM> (cf. e.g. <NPL>)), and used by a transmitting side of an AM RLC entity to limit a total number of retransmissions of an RLC packet data unit (PDU). The detection of the RLF in this case may cause the UE to either transit to RRC_IDLE state or initiate a radio resource control (RRC) connection re-establishment procedure.

The maximal number of retransmissions parameter (i.e. maxRetxThreshold configured in RLC-Config) as currently defined e.g. for <NUM> NR applies to RLC AM as defined in 3GPP TS <NUM>, where value t1 corresponds to <NUM> retransmission, value t2 corresponds to <NUM> retransmissions and so on. If the maximal number of retransmissions of an RLC entity is reached in an exemplary single cell scenario, a RLF will be declared, which will trigger the UE to re-establish the RRC connection with NW - as described above. More specifically, all radio bearers (RBs) except SRB0 will be suspended at the time when the RLF is declared. These suspended RBs (i.e., SRB2 and DRBs) can be resumed first upon receiving the first RRCReconfiguration message after the RRC connection re-establishment procedure is successfully completed. Thus, the user-plane data cannot be transmitted during the time when the DRBs are being resumed, thus causing an undesired interruption in the running applications.

As per TS <NUM>, RLC-Config is comprised within the IE RLC-BearerConfig, which is used to configure an RLC entity and the corresponding logical channel (LCH) in MAC for uplink (besides the linking to a PDCP entity). Thus, distinct RLC entities can be configured for the UE (e.g. for different logical channels) and these can be configured differently, e.g. with different values for the maximal number of retransmissions.

In the current definition of RLF, as currently defined e.g. for <NUM> NR, a RLC failure for one logical channel / RLC entity (e.g., when reaching the maxRetxThreshold) implies the declaration of an RLF, and in turn, the suspending of all DRBs, which will interrupt the data transmission on any other DRB.

As an example, first, when an RLC failure happens, it could be due to a radio condition and/or protocol problems. In case of radio problems, it means that even RLC retransmissions cannot help recovering from radio losses. Although it can be expected that typically a radio link monitoring (RLM) procedure can detect a radio issue before an RLC failure happens, the RLM procedure as currently defined e.g. for <NUM> NR is limited to a primary cell (PCell). Thus, RLC failures may occur likely due radio problems on secondary cells (SCells) or due to a protocol failure (including a configuration issue), rather than a radio issue only on the PCell.

Besides, <NUM> NR also introduced a restriction of "allowed cells" an LCH can use which is different to legacy LTE in that an RLC failure for a LCH might only be a problem for those allowed cells for that LCH (e.g. if they are unlicensed cells, high frequency cells etc.) but should not impact other LCHs if they are using different cells with higher reliability/better channel quality.

This means that, according to some embodiments, an RLC failure of one RLC entity may not imply that another other logical channel cannot be supported adequately. This is an aspect which may be especially relevant when different service types with divergent quality of service (QoS) requirements coexist in a device. For example, achieving the maxRetxThreshold value from a logical channel used for a ultra-reliable and low-latency communication (URLLC) service should not necessarily trigger a suspension of logical channels with more relaxed QoS requirements, e.g. logical channels used to support massive machine type communication (mMTC) and/or enhanced mobile broadband (eMBB) services.

As a further example, secondly, the re-establishment that is triggered because of an RLC failure may be a comparatively slow procedure since it may include a cell selection (of the old or a new cell), a random-access procedure to the selected cell, with several RRC messages to be exchanged. In case of an RLC failure that is caused by protocol / configuration issues, a recovery attempt by the same cell (e.g. by reconfiguring the affected RLC entity) may be likely successful. But that would be initiated only after an unnecessary delay due to the re-establishment.

Some embodiments address aspects such as e.g. a method for handling RLC failures which aims at a faster recovery of an affected RLC entity (i.e. the RLC entity that detected the RLC failure(s)), while at the same time they may allow non-affected RLC entities to continue their service.

According to some embodiments, as already mentioned above, a user equipment may use the RLC failure configuration provided e.g. by configuration via the apparatus according to some embodiments to determine how to react to such RLC failure.

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

According to some embodiments, the RLC failure configuration defines whether the user equipment should notify the RLC failure of the first logical channel to a network when at least a second logical channel associated with the user equipment operates normally, i.e. does not experience an RLC failure. According to some embodiments, this may enable to keep a normal, i.e. uninterrupted, operation for at least the second LCH and/or RB associated therewith, e.g. rather than declaring a RLF and initiating a re-establishment.

As an example, a second logical channel associated with the user equipment operates normally, e.g. when the second logical channel has not reached a predetermined number (e.g. a first threshold or the maximum RLC retransmission number) of RLC retransmissions.

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

According to some embodiments, the UE may be configured with an individual RLC failure configuration per LCH, which enables to provide different LCHs with different RLC failure configurations.

According to some embodiments, the instructions, when executed by the at least one processor, further cause the apparatus to explicitly configure the user equipment with the RLC failure configuration.

According to some embodiments, the user equipment may also be configured implicitly with the RLC failure configuration.

According to some embodiments, which may e.g. be based on a multi-cell carrier aggregation (CA) / dual connectivity (DC) scenario, per-LCH configuring whether an RLC failure for an LCH should trigger an RLC failure report rather than re-establishment may be done implicitly, e.g. based on an allowed cell configuration for the LCH.

According to some embodiments, the implicit configuration may be part of the allowed cell configuration and may be enabled/disabled per UE. For instance, the configured cells that are allowed for a failed LCH, i.e. the first LCH, can be considered failed and may thus be suspended/deactivated, as long as there is at least another cell not failed and 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, e.g. if any other cell is also failed or no other non-failed LCH is mapped to a cell, an RRC re-establishment is initiated.

In some embodiments, the allowed cells are unlicensed cells and/or high frequency cells (e.g., using the frequency range FR2 as e.g. defined by 3GPP <NUM>-<NUM>, cf. e.g. <NPL>), Table <NUM>-<NUM>), since these may be more prone to radio errors. This ensures that problems on these cells will not impact other LCHs if they are using different cells with higher reliability/better channel quality.

In some embodiments, the RLC failure configuration comprises a first threshold, wherein the user equipment may determine, based on the first threshold, whether to transmit the RLC failure to a or the network.

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

According to some embodiments, which may e.g. be based on a single-cell scenario or a multi-cell CA/DC scenario, the first threshold may be seen as a new (additional) threshold in view of the existing threshold parameter "maxRetxThreshold", which is configured in the information element (IE) "RLC-Config", as per 3GPP TS <NUM> (cf. e.g. <NPL>)).

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

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

According to some embodiments, the RLC failure configuration comprises a first control information indicating to the user equipment whether to disable at least one mapping restriction.

According to some embodiments, which may e.g. be based on a single-cell scenario or a multi-cell CA/DC scenario, upon detecting that a given number of RLC AM retransmissions is reached for an RLC entity/LCH (corresponding e.g. to the maximum number defined for RLF detection (e.g., existing "maxRetxThreshold") or to 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, cf. e.g. <NPL>), e.g. chapter <NUM>. <NUM>), the UE may disable at least one of those mapping restrictions (e.g., instead of triggering a RLF), which may be beneficial to get data to be transmitted through as soon as possible, and which may exemplarily be referred to as some actions of the "recovery behavior" according to some embodiments.

According to some embodiments the disabling of least one of those mapping restrictions may be performed automatically, i.e. without an explicit instruction to be received by the UE.

According to some embodiments, enabling this "recovery behavior" may depend on a network configuration. The configuration (e.g., in addition to the possible first threshold according to some embodiments explained above) may indicate which LCP mapping restrictions to disable (e.g., via an information element (IE) "RestrictionsDisableList"). For instance, according to some embodiments, after disabling a restriction according to "allowedServingCells", the UE may fill an UL grant applicable to a 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 be implicitly indicative for the network that the UE has disabled the (LCP mapping) restriction, and in turn that the UE has experienced an RLC failure or the UE has reached the first threshold according to some embodiments explained above.

According to some embodiments, the first control information indicates which of a plurality of mapping restrictions to disable.

The RLC failure configuration comprises at least one priority threshold. In an embodiment useful for understanding the invention, the user equipment may determine, based on the at least one priority threshold whether to transmit the RLC failure to a or the network.

The user equipment may determine, based on the at least one priority threshold and based on at least one of a) a lowest priority of logical channels associated with the user equipment, b) a priority of the first logical channel, whether to transmit the RLC failure to a or the network.

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

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

According to some embodiments, the instructions, when executed by the at least one processor, further cause the apparatus to configure the user equipment, for example an LCH/RLC entity, with a second control information, for example a flag, indicating at least one of: a) the user equipment should declare a radio link failure upon detection of the RLC failure of the first logical channel, b) the user equipment should transmit the RLC failure of the first logical channel to the network, e.g. in the form of an RLC failure report, c) the user equipment should declare a radio link failure upon detection of an RLC failure of at least one other logical channel than the first logical channel, d) the user equipment should transmit the RLC failure report upon detection of an RLC failure of at least one other logical channel than the first logical channel.

According to some embodiments, the second control information, for example the flag, can be set considering the QoS requirements of the LCH/RLC entity and/or the set of configured LCH/RLC entities.

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

According to some embodiments, the value of the first threshold and/or the conditions to declare a radio link failure and/or to send an RLF failure report can be set considering UE-specific conditions, e.g. the existing services in the UE and optionally also their QoS requirements. For instance, if both an eMBB service and a URLLC service coexist according to some embodiments, an RLC failure only from the URLLC service will not declare an RLF.

According to some embodiments, a or the first threshold and a second threshold may be configured, and the UE may send an RLC failure report to the NW if the highest value of the maximal number of retransmissions parameter (i.e. "maxRetxThreshold" configured in RLC-Config) as currently defined e.g. by <NUM> NR for an existing logical channel is higher than the first configured threshold, and the value of the "maxRetxThreshold" of the LCH detecting RLC failure is lower than the second configured threshold. In this option, the UE can ensure a large difference in terms of maxRetxThreshold between the declaring LCH (LCH that declares a RLF) and other LCHs. Thus, the RLC failure of the affect RLC entity should not affect the operation of another LCH.

According to some embodiments, the instructions, when executed by the at least one processor, further cause the apparatus to broadcast at least a part of the RLC failure configuration, for example at least one of: the first threshold, the second threshold.

According to some embodiments, the apparatus or the network may broadcast at least a part of the RLC failure configuration, for example at least one of the first threshold, the second threshold, in a system information block (SIB).

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

According to some embodiments, determining the RLC failure configuration may comprise at least one of: receiving (e.g., for embodiments with explicit configuration) the RLC failure configuration from an apparatus, e.g. an apparatus according to the embodiments, and/or a gNB, determining the RLC failure configuration from other data and/or configuration (e.g., for embodiments with implicit configuration).

According to some embodiments, at least some of the RLC failure configuration at the user equipment may also be specified in a standard, e.g. in a 3GPP technical specification, and/or may be provisioned by UE-implementation.

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

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

According to some embodiments, the RLC failure configuration comprises a first threshold, wherein the instructions, when executed by the at least one processor, further cause the user equipment to determine, based on the first threshold, whether to transmit the RLC failure to a or the network.

According to some embodiments, the RLC failure configuration comprises a first control information indicating to the user equipment whether to disable at least one mapping restriction, wherein the instructions, when executed by the at least one processor, further cause the user equipment to disable the at least one mapping restriction based on the first control information.

According to some embodiments, the RLC failure configuration comprises at least one priority threshold, wherein the instructions, when executed by the at least one processor, further cause the user equipment to determine, based on the at least one priority threshold, and optionally, on at least one of: a) a lowest priority of logical channels associated with the user equipment, b) a priority of the first logical channel, whether to transmit the RLC failure to a or the network.

According to some embodiments, the instructions, when executed by the at least one processor, further cause the user equipment to: determine whether a predetermined number of RLC retransmissions is reached for a logical channel served by a first cell, and, if the predetermined number of RLC retransmissions is reached for the logical channel, 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 a predetermined number of RLC retransmissions.

According to some embodiments, the predetermined number of RLC retransmission may be the configured first threshold or a maximum RLC retransmission number.

According to some embodiments, the instructions, when executed by the at least one processor, further cause the user equipment to: determine if it can re-select another cell, which has a radio channel quality better than a first quality threshold, and, if it can re-select another cell, which has a radio channel quality better than the first quality threshold, to re-establish a radio resource control, RRC, connection with the other cell based on the RLC failure configuration, and, if it cannot re-select another cell, which has a radio channel quality better than the first quality threshold, to determine whether to send an RLC failure report to a current serving cell based on the RLC failure configuration.

According to some embodiments, the UE's upper layers may be configured, e.g. by the apparatus and/or the network, to act differently upon receiving a report of RLC failure from an RLC entity: According to some embodiments, the upper layers may analyze the affected services due to the RLC failure (i.e., the service(s) with data to be transmitted in the logical channel detecting the RLC failure).

According to some embodiments, the upper layers of the UE may check if certain service/application(s) cannot be supported any more, e.g. due to the RLC failure of the first LCH. According to some embodiments, if a service has strict QoS requirements, it probably needs to be stopped due to the unavailability of the LCH detecting the RLC failure. In this case, according to some embodiments, if this service uses multiple LCHs and some of these LCHs are only used by this service, the RLC failure message may also contain an information/recommendation to suspend the LCHs/RBs, which are only used by the affected service. This may ensure the LCHs only serving the affected service will be suspended. According to some embodiments, after its suspension, the LCH will not be used in the following transmission until it is resumed and/or reconfigured.

According to some embodiments, if the affected service can adjust itself to tolerate the deteriorated performance, 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 the NW with the flexibility to decide whether to reconfigure the affected LCH/DRB or to suspend it. According to some embodiments, again, an indication of the LCH(s) only serving the affected service can be included in the RLC failure report so that the NW can make a decision with better knowledge.

Some embodiments relate to a method of operating an apparatus for a wireless communications system, comprising: configuring a user equipment with a radio link control, RLC, failure configuration which defines how the user equipment should react to an RLC failure of a first logical channel associated with the user equipment.

Some embodiments relate to a method of operating a user equipment, comprising: determining a radio link control, RLC, failure configuration which defines how the user equipment should react to an RLC failure of a first logical channel associated with the user equipment.

Though some of the elaborations and embodiments use the radio interface between a UE and a network, e.g. gNB, according to some embodiments, the basic principle may also be applied for other communications and/or radio interfaces as well, e.g. to handle an RLC failure of a sidelink (SL) RLC entity that may be used for a sidelink communication between two user devices, e.g., UEs, for example under a PC5-RRC connection.

For example, according to some embodiments, the transmission of a SL LCH between two SL UEs may take place via multiple SL carriers or two resource pools and, thus, the proposed solution for multi-cell scenario according to some embodiments can be applied by considering the SL transmissions via multiple SL carriers or multiple SL resource pools.

In other embodiments, the approach of some embodiments depicted for a single cell scenario may be applied for transmitting a SL LCH between the 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 referring to some embodiments for a communication between a UE and network, e.g. to avoid PC5-RLC declaration and allow that service can continue for other SL RLC entities/LCHs despite an SL RLC failure is affecting one SL RLC entity/LCH.

According to some embodiments, it is noted that, in case of sidelink communication, a (re)-configuration of a UE's SL RB/RLC entity/LCH may be performed either by the SL UE itself or by the network, depending on the SL transmission mode and/or the UE RRC state.

Some exemplary embodiments will now be described with reference to the accompanying drawings in which:.

Some embodiments relate to an apparatus for a wireless communications system. <FIG> schematically depicts a simplified block diagram of the apparatus <NUM> according to some embodiments, and <FIG> schematically depicts a simplified flow chart of a method of operating the apparatus according to some embodiments. The apparatus <NUM> (<FIG>) comprises at least one processor <NUM>, and memory <NUM> storing instructions <NUM> that, when executed by the at least one processor <NUM>, cause the apparatus <NUM> at least to configure <NUM> (cf. <FIG>) a user equipment with a radio link control, RLC, failure configuration RLC-FCFG which defines how the user equipment should react to an RLC failure of a first logical channel associated with the user equipment.

According to some embodiments, some of the RLC failure configuration at the user equipment may also be specified in a standard, e.g. in a 3GPP technical specification or the like, and/or may be provisioned by UE-implementation.

In some embodiments, after configuring <NUM> the user equipment with the RLC failure configuration RLC-FCFG, the apparatus <NUM> may receive, cf. step <NUM> of <FIG>, an RLC failure from the user equipment, e.g. in the form of at least one RLC failure report RLC-FR.

In some embodiments, the apparatus <NUM> (<FIG>) may comprise a transceiver <NUM> for exchanging, i.e. transmitting and/or receiving, radio frequency, RF, signals with other components such as e.g. user equipment, UE, <NUM>, cf. e.g. <FIG>, and/or further devices (not shown).

<FIG> schematically depicts a simplified block diagram of a communications system <NUM> according to some embodiments. The communications system <NUM> may e.g. comprise the apparatus <NUM>. The communications system <NUM> may further comprise at least one user equipment, UE, <NUM>. Reference sign <NUM>' denotes optional further UE.

In some embodiments, the apparatus <NUM> or its functionality, respectively, may be provided in a network element of the communications systems <NUM>, for example in a base station <NUM>, e.g. a gNodeB (gNB) <NUM>.

In some embodiments, the apparatus <NUM> according to the embodiments or its functionality, respectively, may be used for or within wireless communications systems <NUM> based on or at least partially adhering to third generation partnership project, 3GPP, radio standards such as <NUM> E-UTRAN or <NUM> NR (fifth generation new radio). In some embodiments, the apparatus <NUM> according to the embodiments or its functionality, respectively, may be used for a radio link failure (RLF), procedure of <NUM> NR-based communications systems <NUM>.

In some embodiments, the UE <NUM>, also cf. <FIG>, may comprise at least one processor <NUM>, and memory <NUM> storing instructions, e.g. in the form of computer program code <NUM>.

Optionally, according to further exemplary embodiments, the UE <NUM> may comprise a transceiver <NUM> for exchanging, i.e. transmitting and/or receiving, radio frequency, RF, signals with other components such as e.g. the apparatus <NUM> or the gNB <NUM> (<FIG>), and/or further devices (not shown).

As an example, one triggering condition for an RLF in a Uu interface as currently defined e.g. for <NUM> NR is characterized as follows: upon indication from a radio link control (RLC) layer that a maximum number of RLC retransmissions has been reached when using an RLC acknowledged mode (AM). According to this triggering condition, a maximal number of retransmissions in RLC is configured by using a parameter "maxRetxThreshold", which is configured in the information element (IE) "RLC-Config", as per 3GPP TS <NUM> (cf. e.g. <NPL>)), and used by a transmitting side of an AM RLC entity to limit a total number of retransmissions of an RLC packet data unit (PDU).

As per TS <NUM>, RLC-Config is comprised within the IE RLC-BearerConfig, which is used to configure an RLC entity and the corresponding logical channel (LCH) in MAC for uplink (besides the linking to a PDCP entity). Thus, distinct RLC entities can be configured for the UE <NUM> (e.g. for different logical channels) and these can be configured differently, e.g. with different values for the maximal number of retransmissions.

In view of this, some embodiments address aspects such as e.g. a method for handling RLC failures which aims at a faster recovery of an affected RLC entity (i.e. the RLC entity that detected the RLC failure(s)), while at the same time they may allow non-affected RLC entities to continue their service.

According to some embodiments, as already mentioned above, the user equipment <NUM> (<FIG>) may use the RLC failure configuration RLC_FCFG (<FIG>) provided e.g. by configuration via the apparatus <NUM> according to some embodiments to determine how to react to such RLC failure.

According to some embodiments, the RLC failure configuration RLC_FCFG defines whether the user equipment <NUM> should notify the RLC failure of the first logical channel to the network, e.g. to apparatus <NUM> or the gNB <NUM>.

According to some embodiments, the RLC failure configuration defines whether the user equipment <NUM> should notify the RLC failure of the first logical channel to the network, when at least a second logical channel associated with the user equipment <NUM> operates normally, i.e. does not experience an RLC failure. According to some embodiments, this may enable to keep a normal, i.e. uninterrupted, operation for at least the second LCH and/or RB associated therewith, e.g. rather than declaring a RLF and initiating a re-establishment.

As an example, a second logical channel associated with the user equipment operates normally, e.g. when the second logical channel has not reached a predetermined number (e.g. the first threshold or the maximum RLC retransmission number) of RLC retransmissions.

According to some embodiments, the UE <NUM> may be configured with multiple LCHs and/or RLC entities.

According to some embodiments, the UE <NUM> may be configured with an individual RLC failure configuration RLC_FCFG per UE or per LCH. In case of per LCH RLC failure configuration RLC_FCFG, it enables to provide different LCHs with different RLC failure configurations.

According to some embodiments, the instructions <NUM> (<FIG>), when executed by the at least one processor <NUM>, further cause the apparatus <NUM> to explicitly configure the user equipment <NUM> with the RLC failure configuration RLC_FCFG. According to some embodiments, the RLC failure configuration RLC_FCFG may be explicitly provided to the UE <NUM>, e.g. together with further information transmitted from the apparatus <NUM> to the UE <NUM>, such as e.g. a configuration for RLC entities of the UE <NUM>.

According to some embodiments, the user equipment <NUM> may also be configured implicitly with the RLC failure configuration RLC-FCFG.

According to some embodiments, the implicit configuration may be part of the allowed cell configuration and may be enabled/disabled per UE <NUM>, <NUM>' (<FIG>). For instance, the configured cells that are allowed for a failed LCH, i.e. the first LCH, can be considered failed and may thus be suspended/deactivated, as long as there is at least another cell not failed and 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, e.g. if any other cell is also failed or no other non-failed LCH is mapped to a cell, an RRC re-establishment is initiated.

In some embodiments, cf. <FIG>, the RLC failure configuration RLC_FCFG comprises a first threshold T1, wherein the user equipment <NUM> may determine, based on the first threshold, whether to transmit the RLC failure to the network, e.g. to the gNB <NUM>.

In some embodiments, the first threshold T1 may be a predetermined number of RLC retransmissions.

According to some embodiments, which may e.g. be based on a single-cell scenario or a multi-cell CA/DC scenario, the first threshold T1 may be seen as a new (additional) threshold in view of the existing threshold parameter "maxRetxThreshold", which is configured in the information element (IE) "RLC-Config", as per 3GPP TS <NUM> (cf. e.g. <NPL>)).

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

According to some embodiments, the value of the first threshold T1 "maxRetxThreshold_RLCReport" can be set lower than the existing "maxRetxThreshold", e.g. to first trigger a report. According to some embodiments, this enables an attempt to first recover/solve an RLC failure issue, e.g. by reconfiguring of protocol parameters for the affected (first) LCH or changing the allowed cells and/or other LCP restrictions, before declaring an RLF and suspending all DRBs.

According to some embodiments, the RLC failure configuration RLC-FCFG (<FIG>) comprises a first control information CI1 indicating to the user equipment <NUM> whether to disable at least one mapping restriction.

According to some embodiments, which may e.g. be based on a single-cell scenario or a multi-cell CA/DC scenario, upon detecting that a given number of RLC AM retransmissions is reached for an RLC entity/LCH (corresponding e.g. to the maximum number defined for RLF detection (e.g., existing "maxRetxThreshold") or to 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, cf. e.g. <NPL>), e.g. chapter <NUM>. <NUM>), the UE <NUM> (<FIG>) may disable at least one of those mapping restrictions (e.g., instead of triggering a RLF), which may be beneficial to get data to be transmitted through as soon as possible, and which may exemplarily be referred to as some actions of the "recovery behavior" according to some embodiments.

According to some embodiments, the disabling of least one of those mapping restrictions may be performed automatically, i.e. without an explicit instruction to be received by the UE <NUM>.

According to some embodiments, enabling this "recovery behavior" may depend on a network configuration. The configuration (e.g., in addition to the possible first threshold T1 according to some embodiments explained above) may indicate which LCP mapping restrictions to disable (e.g., via an information element (IE) "RestrictionsDisableList"). For instance, according to some embodiments, after disabling a restriction according to "allowedServingCells", the UE <NUM> may fill an UL grant applicable to a 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 be implicitly indicative for the network that the UE <NUM> has disabled the (LCP mapping) restriction, and in turn that the UE <NUM> has experienced an RLC failure or the UE has reached the first threshold according to some embodiments explained above.

According to some embodiments, the first control information CI1 indicates which of a plurality of mapping restrictions to disable.

According to some embodiments, the RLC failure configuration RLC-FCFG (<FIG>) comprises at least one priority threshold P1, P2, wherein the user equipment <NUM> may determine, based on the at least one priority threshold P1, P2 whether to transmit the RLC failure to the network.

According to some embodiments, the user equipment <NUM> may determine, based on the at least one priority threshold P1, P2 and on at least one of: a) a lowest priority of logical channels associated with the user equipment <NUM>, b) a priority of the first logical channel, whether to transmit the RLC failure to the network.

According to some embodiments, a first priority threshold P1 and a second priority threshold P2 may be provided, e.g. by network or by pre-configuration.

According to some embodiments, which may e.g. be based on a single-cell scenario or a multi-cell CA/DC scenario, the UE <NUM> may send an RLC failure report RLC-FR (<FIG>) to the NW <NUM> or apparatus <NUM> if the lowest priority of all existing logical channels is lower than the first configured threshold P1, and the priority of the LCH detecting RLC failure is higher than the second threshold P2. According to some embodiments, if another LCH with certain (i.e., non-vanishing) QoS difference and/or configuration difference comparing to the LCH detecting the RLC failure is configured, the RLC failure from the affected LCH (i.e. the one detecting the RLC failure) need not imply the failure of the other LCH and, thus, the other LCH should not be affected. Alternatively, according to some embodiments, it is configured per LCH or a priority threshold if a failure happens to an LCH with higher or lower priority than a configured threshold, RLC failure report RLC-FR is triggered.

According to some embodiments, the instructions <NUM> (<FIG>), when executed by the at least one processor <NUM>, further cause the apparatus <NUM> to configure <NUM> the user equipment <NUM>, for example an LCH/RLC entity, with a second control information CI2 (<FIG>), for example a flag, indicating at least one of: a) the user equipment <NUM> should declare a radio link failure upon detection of the RLC failure of the first logical channel, b) the user equipment <NUM> should transmit the RLC failure of the first logical channel to the network, e.g. in the form of an RLC failure report RLC-FR, c) the user equipment <NUM> should declare a radio link failure (RLF) upon detection of an RLC failure of at least one other logical channel than the first logical channel, d) the user equipment <NUM> should transmit the RLC failure report upon detection of an RLC failure of at least one other logical channel than the first logical channel.

According to some embodiments, the second control information CI2, for example the flag, can be set considering the QoS requirements of the LCH/RLC entity and/or the set of configured LCH/RLC entities.

According to some embodiments, the instructions <NUM>, when executed by the at least one processor <NUM>, further cause the apparatus <NUM> to set at least a part of the RLC failure configuration RLC-FCFG based on at least one user equipment specific condition.

According to some embodiments, the value of the first threshold T1 and/or the conditions to declare a radio link failure and/or to send an RLF failure report can be set considering UE-specific conditions, e.g. the existing services in the UE <NUM> and optionally also their QoS requirements. For instance, if both an eMBB service and a URLLC service coexist according to some embodiments, an RLC failure only from the URLLC service may not declare an RLF.

According to some embodiments, a or the first threshold and a second threshold may be configured, and the UE <NUM> may send an RLC failure report to the NW if the highest value of the maximal number of retransmissions parameter (i.e. "maxRetxThreshold" configured in RLC-Config) as currently defined e.g. by <NUM> NR for an existing logical channel is higher than the first configured threshold, and the value of the "maxRetxThreshold" of the LCH detecting RLC failure is lower than the second configured threshold. In this option, the UE <NUM> can ensure a large difference in terms of maxRetxThreshold between the declaring LCH (LCH that declares a RLF) and other LCHs. Thus, the RLC failure of the affected RLC entity should not affect the operation of another LCH.

According to some embodiments, the instructions <NUM>, when executed by the at least one processor <NUM>, further cause the apparatus <NUM> to broadcast at least a part of the RLC failure configuration RLC-FCFG (<FIG>), for example at least one of: the first threshold, the second threshold.

According to some embodiments, the apparatus <NUM> or the network may broadcast at least a part of the RLC failure configuration, for example at least one of the first threshold, the second threshold, in a system information block (SIB).

Further embodiments relate to the UE <NUM> (<FIG>) comprising the processor <NUM>, and memory <NUM> storing instructions <NUM> that, when executed by the at least one processor <NUM>, cause the user equipment <NUM> at least to, also cf. the flow chart of <FIG>, determine <NUM> the radio link control, RLC, failure configuration RLC-FCFG, which defines how the user equipment <NUM> should react to an RLC failure of a first logical channel associated with the user equipment <NUM>.

According to some embodiments, determining <NUM> the RLC failure configuration RLF-FCFG may comprise at least one of: receiving (e.g., for embodiments with explicit configuration) the RLC failure configuration RLC-FCFG from an apparatus, e.g. an apparatus <NUM> according to the embodiments, and/or a gNB <NUM>, determining the RLC failure configuration RLC-FCFG from other data and/or configuration (e.g., for embodiments with implicit configuration).

According to some embodiments, the instructions <NUM>, when executed by the at least one processor <NUM>, further cause the user equipment <NUM> to determine <NUM>, based on the RLC failure configuration RLC-FCFG, whether the user equipment <NUM> should notify the RLC failure of the first logical channel to the network, e.g. when at least a second logical channel associated with the user equipment <NUM> operates normally.

According to some embodiments, the instructions <NUM>, when executed by the at least one processor <NUM>, further cause the user equipment <NUM> to determine <NUM> (<FIG>) the RLC failure configuration RLC-FCFG based on a configuration of allowed cells for at least one logical channel.

According to some embodiments, the RLC failure configuration comprise the first threshold T1, wherein the instructions <NUM>, when executed by the at least one processor <NUM>, further cause the user equipment <NUM> to determine <NUM> (<FIG>), based on the first threshold T1, whether to transmit the RLC failure to the network.

According to some embodiments, the RLC failure configuration comprises the first control information CI1 indicating to the user equipment <NUM> whether to disable at least one mapping restriction, wherein the instructions <NUM>, when executed by the at least one processor <NUM>, further cause the user equipment <NUM> to disable <NUM> (<FIG>) the at least one mapping restriction based on the first control information.

According to some embodiments, the RLC failure configuration RLC-FCFG comprises the at least one priority threshold P1, P2, wherein the instructions <NUM>, when executed by the at least one processor <NUM>, further cause the user equipment <NUM> to determine, based on the at least one priority threshold, and optionally, on at least one of: a) a lowest priority of logical channels associated with the user equipment, b) a priority of the first logical channel, whether to transmit the RLC failure to the network.

According to some embodiments, the instructions <NUM>, when executed by the at least one processor <NUM>, further cause the user equipment <NUM> to: determine whether a predetermined number of RLC retransmissions is reached for a logical channel served by a first cell, and, if the predetermined number of RLC retransmissions is reached for the logical channel, 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 a predetermined number of RLC retransmissions.

According to some embodiments, the instructions <NUM>, when executed by the at least one processor <NUM>, further cause the user equipment <NUM> to: determine if it can re-select another cell, which has a radio channel quality better than a first quality threshold, and, if it can re-select another cell, which has a radio channel quality better than the first quality threshold, to re-establish a radio resource control, RRC, connection with the other cell based on the RLC failure configuration, and, if it cannot re-select another cell, which has a radio channel quality better than the first quality threshold, to determine whether to send an RLC failure report to a current serving cell based on the RLC failure configuration.

According to some embodiments, the UE's upper layers may be configured, e.g. by the apparatus <NUM> and/or the network or gNB <NUM>, to act differently upon receiving a report of RLC failure from an RLC entity: According to some embodiments, the upper layers may analyze the affected services due to the RLC failure (i.e., the service(s) with data to be transmitted in the logical channel detecting the RLC failure).

According to some embodiments, the upper layers of the UE <NUM> may check if certain service/application(s) cannot be supported any more, e.g. due to the RLC failure of the first LCH. According to some embodiments, if a service has strict QoS requirements, it probably needs to be stopped due to the unavailability of the LCH detecting the RLC failure. In this case, according to some embodiments, if this service uses multiple LCHs and some of these LCHs are only used by this service, the RLC failure message may also contain an information/recommendation to suspend the LCHs/RBs, which are only used by the affected service. This may ensure the LCHs only serving the affected service will be suspended. According to some embodiments, after its suspension, the LCH will not be used in the following transmission until it is resumed and/or reconfigured.

According to some embodiments, if the affected service can adjust itself to tolerate the deteriorated performance, the UE <NUM> may indicate this in the RLC failure report RLC-FR (<FIG>), e.g. by including a corresponding indication in the RLC failure report RLC-FR. According to some embodiments, this indication may provide the NW with the flexibility to decide whether to reconfigure the affected LCH/DRB or to suspend it. According to some embodiments, again, an indication of the LCH(s) only serving the affected service can be included in the RLC failure report so that the NW can make a decision with better knowledge.

<FIG> schematically depicts a simplified flow chart of a method according to some embodiments. In step <NUM>, the UE <NUM> (<FIG>) may be configured with multiple LCHs/RLC entities, and with an RLC failure configuration RLC-FCFG, for example an RLC failure configuration RLC-FCFG per LCH. In step <NUM>, the UE <NUM> determines whether a RLC failure is detected for an LCH (i.e., one of the multiple LCHs configured in step <NUM>). If not, the method returns to step <NUM>. If an RLC failure is detected for an LCH, i.e. the first LCH, the method proceeds with step <NUM>, in which the RLC entity affected by the RLC failure sends an indication to the UE's RRC layer. In step <NUM> it is determined by the UE <NUM>, based on the RLC failure configuration RLC-FCFG, whether to trigger an RLC failure report. If, in step <NUM>, it is determined to trigger the RLC failure report, the method proceeds with step <NUM>, in which the UE <NUM> may send the RLC failure report RLC-FR (<FIG>) to the network (e.g., the apparatus <NUM> and/or the gNB <NUM>) and/or, according to some embodiments, if configured, disable at least one of the mapping restrictions, e.g. disable the allowed cells restrictions for the affected LCH.

If, in step <NUM>, it is determined not to trigger the RLC failure report, the method proceeds with step <NUM>, in which it is determined whether an RLF declaration is triggered. If so, the method proceeds with step <NUM>, in which the UE <NUM> initiates an RRC re-establishment procedure. If not, the method proceeds with step <NUM>. In some embodiments, advantageously, an RRC re-establishment procedure, cf. step <NUM> of <FIG>, may be avoided. Instead, step <NUM> may be performed.

<FIG> schematically depicts a simplified flow chart of a method according to some embodiments. Note that user-plane transmissions are not shown for the sake of simplicity. Reference sign <NUM> symbolizes a configuration RLC-Config for one or more RLC entities of the UE <NUM>. According to some embodiments, the configuration <NUM> may also comprise the RLC failure configuration RLC-FCFG (also cf. <FIG>) according to some embodiments, e.g. comprising the first threshold T1 (also cf. <FIG>) and/or the "RestrictionsDisableList" IE explained above, e.g. for UL-AM-RLC. Reference sign <NUM> symbolizes an LCP restriction configuration e.g. characterizing LCP mapping restrictions according to allowedCG_list, allowedPriorityLevels, and allowedServingCells, cf. e.g. <NPL>), e.g. chapter <NUM>. Block <NUM> indicates a step of radio link monitoring (RLM) performed by the UE <NUM>, and block <NUM> indicates a detection of a configured trigger for an RLC failure report, and, according to some embodiments, disabling the LCP restriction(s) as configured earlier, cf. reference sign <NUM>. Arrow <NUM> indicates a transmission of RLC failure information to the gNB <NUM>, and block <NUM> characterizes a network action as performed upon receipt of, e.g. based on, the RLC failure information. According to some embodiments, the network action <NUM> may comprise a reconfiguration. Accordingly, arrow <NUM> may represent a reconfiguration message to the UE <NUM>, such as an RRCReconfiguration, which may e.g. include a (new) RLC configuration. Block <NUM> indicates the UE reconfiguring the LCH affected by the RLC failure, and may, according to some embodiments, also comprise enabling the previously disabled (cf. block <NUM>) LCP restrictions. Alternatively, the UE may enable the LCP restrictions in Block <NUM> based on the reconfiguration message received in <NUM>.

<FIG> schematically depicts a simplified flow chart of a method according to some embodiments. Note that, similar to <FIG>, user-plane transmissions are not shown for the sake of simplicity. Similar to arrow <NUM> of <FIG>, reference sign <NUM> of <FIG> symbolizes a configuration RLC-Config for one or more RLC entities of the UE <NUM>. According to some embodiments, the configuration <NUM> may also comprise the RLC failure configuration RLC-FCFG (also cf. <FIG>) according to some embodiments, e.g. comprising the first threshold T1 (also cf. <FIG>) and/or the "RestrictionsDisableList" IE explained above, e.g. for UL-AM-RLC. Reference sign <NUM> symbolizes an LCP restriction configuration e.g. characterizing LCP mapping restrictions according to allowedCG_list, allowedPriorityLevels, and allowedServingCells, as mentioned above. Similar to blocks <NUM>, <NUM> of <FIG>, blocks <NUM>, <NUM> of <FIG> indicate a step of radio link monitoring (RLM) performed by the UE <NUM> (block <NUM>) and a detection of a configured trigger for an RLC failure report, and, according to some embodiments, disabling the LCP restriction(s) as configured earlier, cf. reference sign <NUM> (block <NUM>).

According to some embodiments, the RLC failure information may also be implicitly indicated to the network, once the network detects from uplink reception that the UE <NUM> has disabled the LCP restriction(s).

According to some embodiments, one or more of the following network actions, e.g. legacy network actions, may be performed, which may be triggered by receiving the RLC failure indication (cf. e.g. arrow <NUM> of <FIG>). According to some embodiments, the network actions may take place to attempt recovering the service for the LCH/RB affected by the RLC failure:.

According to some embodiments, the RB/LCH affected by the RLC failure is not configured with duplication ("non-duplication scenario").

According to some embodiments, the failure of an LCH/RB operating on a cell may not lead to suspending the entire cell operations but only the affected LCH.

According to some embodiments, one or more services can continue for other RBs despite an RLC failure is affecting one RB, and in the meanwhile, the network may cure the problem related to the RLC failure of the affected RB, e.g. as fast as possible, in turn shortening the recovery time. According to some embodiments, during the recovery is attempted, the affected RLC / LCH (failed) can be served using any cell that is not suspended even if originally that cell was not allowed (i.e. disabling LCP mapping restrictions upon RLC failure according to some embodiments).

In other words, some embodiments do not introduce additional delay in solving an RLC failure affecting the RB as compared to the conventional approaches (e.g., triggering of an RLF and RRC re-establishment), as the RLC failure report should be received by the network at the same time or earlier than the RLF report in most scenarios.

Claim 1:
An apparatus (<NUM>) for a wireless communications system (<NUM>), comprising at least one processor (<NUM>), and memory (<NUM>) storing instructions that, when executed by the at least one processor (<NUM>), cause the apparatus (<NUM>) at least to configure (<NUM>) a user equipment (<NUM>) with a radio link control, RLC, failure configuration, RLC-FCFG, which defines how the user equipment (<NUM>) should react to an RLC failure of a first logical channel associated with the user equipment (<NUM>), wherein the RLC failure configuration comprises at least one priority threshold (P1, P2), and wherein the user equipment (<NUM>) is configured to determine, based on the at least one priority threshold (P1, P2) and on at least one of: a) a lowest priority of logical channels associated with the user equipment, b) a priority of the first logical channel, whether to transmit the RLC failure to a network.