Method to avoid unwanted RLF trigger by RLC layer

Abstract

A method, including configuring a transmitter Radio Link Control (RLC) entity with at least one threshold parameter to trigger Radio Link Failure (RLF) based on the at least one threshold parameter; and determining by the transmitter RLC entity to trigger RLF based on the at least one threshold parameter. The threshold is related to an RLC retransmission threshold.

Description

METHOD TO AVOID UNWANTED RLF TRIGGER BY RLC LAYERCROSS-REFERENCE TO RELATED APPLICATIONSFIELD

[0001] Various example embodiments relate generally to apparatuses, methods, and computer program products that support avoiding unwanted Radio Link Failure (RLF) triggering by the Radio Link Control (RLC) layer.BACKGROUND

[0002] Wireless networking provides significant advantages for user mobility. A user’s ability to remain connected while on the move provides advantages not only for the user, but also provides greater efficiency and productivity for society as a whole. As expectations for connection reliability, data speed, and lower power consumption, become more demanding, technology for wireless networking must also keep pace with such expectations. Accordingly, there is continuing interest in improving wireless networking technology.SUMMARY

[0003] In accordance with aspects of the disclosure, a method includes: configuring a transmitter Radio Link Control (RLC) entity with at least one threshold parameter to trigger Radio Link Failure (RLF) based on the at least one threshold parameter; and determining by the transmitter RLC entity to trigger RLF based on the at least one threshold parameter, wherein the threshold is related to an RLC retransmission threshold.

[0004] In an aspect, the RLF triggering may happen at the transmitter RLC entity. The at least one threshold parameter may be related to a number of times the retransmissions of a at least one of RLC Service Data Units (SDU) have reached the RLC retransmission threshold.

[0005] In an aspect, the method may further include determining, by the transmitter RLC entity, to trigger RLF, that a number of retransmissions for at least one RLC SDUs reaches the RLC retransmission threshold and that a count of the number of packets reached the RLC retransmission threshold.

[0006] In an aspect, the method may further include determining, by the transmitter RLC entity, the triggering of RLF based on whether a number of consecutive number of retransmissions reaches a configured threshold of the at least one threshold parameter.

[0007] In an aspect, the transmitter RLC entity may be further configured with a configured window duration, and the method may further comprise determining, by the transmitter RLC entity, triggering of RLF based on a number of the number of retransmitted RLC SDUs meeting or exceeding the threshold of the at least one threshold parameter within the configured duration.

[0008] In an aspect, the least one threshold parameter may be configured via radio resource control (RRC) or medium access control control element (MAC CE).

[0009] In an aspect, the method may further include: receiving, by the transmitter RLC entity from a receiver RLC entity, a Negative Acknowledgement (NACK) up to a number of times equal to a threshold value, the threshold relating to a maximum number of times the retransmission of at least one RLC SDUs; receiving, by the transmitter RLC entity from the receiver RLC entity, an Acknowledgement (ACK) in a subsequent RLC status report; and causing the receiver RLC entity to update a receiver state variable and causing the transmitter RLC entity to update the transmitter state variable. The transmitter RLC entity and the receiver RLC entity may be configured with a same value for the threshold value relating to a number of times the retransmission and NACKs of at least one RLC SDUs.

[0010] In an aspect, the configured window duration may be a sliding window with overlapping time durations between different durations, or a non-overlapping time between different window durations.

[0011] In an aspect, once the threshold is reached, a lower bound of a RLC receiver window may be moved to a first missed packet greater than a current lower bound for which a status is reported as NACK less than maximum retransmission threshold times.

[0012] In an aspect, the transmitter RLC entity may include a user equipment (UE) or a network node.

[0013] In accordance with aspects of the disclosure, a user equipment (UE) includes: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the UE at least to perform any of the preceding methods.

[0014] In accordance with aspects of the disclosure, a processor-readable medium storing instructions which, when executed by at least one processor of a user equipment (UE), causes the UE at least to perform any of the preceding methods.

[0015] In accordance with aspects of the disclosure, a method includes: configuring a receiver Radio Link Control (RLC) entity with at least one threshold parameter to trigger Radio Link Failure (RLF) based on the at least one threshold parameter; and determining by the receiver RLC entity to trigger RLF based on the at least one threshold parameter.

[0016] In an aspect, the at least one threshold parameter may be related to an RLC retransmission threshold.

[0017] In an aspect, the least one threshold parameter may be configured via radio resource control (RRC) or medium access control control element (MAC CE).

[0018] In an aspect, the method may further include performing, by the receiver RLC entity the RLF triggering. The threshold parameter may be related to a number of times Negative Acknowledgments (NACK) for at least one RLC Service Data Units (SDUs) in RLC status reports have reached the RLC retransmission threshold.

[0019] In an aspect, the method may further include determining by the receiver RLC entity, to trigger RLF, based on a number of NACKs for an RLC SDU reaches the RLC retransmission threshold and that a count of the packets reaches a threshold of the at least one threshold parameter.

[0020] In an aspect, the method may further include determining by the receiver RLC entity, triggering of RLF based on the number of consecutive occurrences of such situations meets or exceeds the threshold of the at least one threshold parameter.

[0021] In an aspect, the receiver RLC entity may be further configured with a configured window duration. The method may further include determining by the receiver RLC entity, triggering of RLF based on a number of such occurrences meeting or exceeding the configured threshold within the configured duration.

[0022] In an aspect, the method may further include considering by the receiver RLC entity, an RLC SDU of the at least one RLC SDUs has been received based on NACKs for the RLC SDU in RLC status reports have reached the RLC retransmission threshold.

[0023] In an aspect, the method may further include: transmitting, by the receiver RLC entity to the transmitter RLC entity, a NACK a number of times equal to a threshold value, the threshold relating to number of times the retransmission of at least one RLC SDUs; transmitting, by the receiver RLC entity to the transmitter RLC entity, an ACK for the at least one RLC SDUs in subsequent RLC status report; and updating a state variable of the receiver RLC entity. The transmitter RLC entity and the receiver RCL entity may be configured with a same value for the threshold value relating to a number of times the retransmission and NACK of at least one RLC SDUs.

[0024] In an aspect, the receiver RLC entity may include a user equipment (UE) or a network node.

[0025] In an aspect, the configured window duration may be a sliding window with overlapping time durations between different durations, or a non-overlapping time between different window durations.

[0026] In accordance with aspects of the disclosure, a network apparatus includes: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the network apparatus at least to perform any of the preceding methods.

[0027] In accordance with aspects of the disclosure, a processor-readable medium storing instructions which when executed by at least one processor of a network apparatus, causes the network apparatus at least to perform any of the preceding methods.

[0028] According to some aspects, there is provided the subject matter of the independent claims. Some further aspects are defined in the dependent claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Some example embodiments will now be described with reference to the accompanying drawings.

[0030] FIG. 1 is a diagram of an example embodiment of wireless networking between a network system and a user equipment (UE), according to one illustrated aspect of the disclosure;

[0031] FIG. 2 is a diagram of example components of a network system, according to one illustrated aspect of the disclosure;

[0032] FIG. 3 is a diagram illustrating an example RLF triggering mechanism using overlapping windows, according to one illustrated aspect of the disclosure;

[0033] FIG. 4 is a diagram illustrating an example RLF triggering mechanism using nonoverlapping windows, according to one illustrated aspect of the disclosure;

[0034] FIG. 5 is a diagram illustrating an example of using MAC Control Element (MAC CE) to reconfigure maxRetxPackets, according to one illustrated aspect of the disclosure;

[0035] FIG. 6 is a diagram illustrating an example of using MAC CE to indicate detected missed packets at a Packet Data Convergence Protocol (PDCP) entity, according to one illustrated aspect of the disclosure;

[0036] FIG. 7 is a diagram of example operations for the RLF triggering mechanism at Layer 2, where the triggering is at either a transmitting RLC entity, a receiving RLC entity, or a receiving PDCP entity, according to one illustrated aspect of the disclosure;

[0037] FIG. 8 is a diagram of example operations for the RLF triggering mechanism at Layer 2, using the window-based mechanism of FIGS. 3 and 4, according to one illustrated aspect of the disclosure; and

[0038] FIG. 9 is a diagram of an example of components of a user equipment or of a network apparatus, according to one illustrated aspect of the present disclosure.DETAILED DESCRIPTION

[0039] The present disclosure relates to products that support avoiding unwanted Radio Link Failure (RLC) triggering by the RLC layer.

[0040] In the following description, certain specific details are set forth in order to provide a thorough understanding of disclosed aspects. However, one skilled in the relevant art will recognize that aspects may be practiced without one or more of these specific details or with other methods, components, materials, etc. In other instances, well-known structures associated with transmitters, receivers, or transceivers have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the aspects.

[0041] Reference throughout this specification to “one aspect” or “an aspect” means that a particular feature, structure, or characteristic described in connection with the aspect is included in at least one aspect. Thus, the appearances of the phrases “in one aspect” or “in an aspect” in various places throughout this specification are not necessarily all referring to the same aspect. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more aspects.

[0042] Embodiments described in the present disclosure may be implemented in wireless networking apparatuses, such as, without limitation, apparatuses utilizing Worldwide Interoperability for Microwave Access (WiMAX), Global System for Mobile communications (GSM, 2G), GSM EDGE radio access Network (GERAN), General Packet Radio Service (GRPS), Universal Mobile Telecommunication System (UMTS, 3G) based on basic wideband-code division multiple access (W-CDMA), high-speed packet access (HSPA), Long Term Evolution (LTE), LTE-Advanced, enhanced LTE (eLTE), 5G New Radio (5G NR), 5G Advance, 6G (and beyond) and 802.1 lax (Wi-Fi 6), among other wireless networking systems. The term ‘eLTE’ here denotes the LTE evolution that connects to a 5G core. LTE is also known as evolved UMTS terrestrial radio access (EUTRA) or as evolved UMTS terrestrial radio access network (EUTRAN).

[0043] The present disclosure may use the term “serving network device” to refer to a network node or network device (or a portion thereof) that services a UE. As used herein, theterms “transmit toward,” “transmit to,” “receive from,” and “cooperate with,” (and their variations) include communications that may or may not involve communications through one or more intermediate devices or nodes. The term “acquire” (and its variations) includes acquiring in the first instance or reacquiring after the first instance. The term “connection” may mean a physical connection or a logical connection.

[0044] The present disclosure uses 5G NR as an example of a wireless network and may use smartphones and / or extended reality headsets as an example of UEs. It is intended and shall be understood that such examples are merely illustrative, and the present disclosure is applicable to other wireless networks and user equipment.

[0045] FIG. l isa diagram depicting an example of wireless networking between a network system 100 and a user equipment (UE) 150. The network system 100 may include one or more network nodes 120, one or more servers 110, and / or one or more network equipment 130 (e.g., test equipment). The network nodes 120 will be described in more detail below. As used herein, the term “network apparatus” may refer to any component of the network system 100, such as the server 110, the network node 120, the network equipment 130, any component(s) of the foregoing, and / or any other component(s) of the network system 100. Examples of network apparatuses include, without limitation, apparatuses implementing aspects of 5G NR, among others. The present disclosure describes embodiments related to 5GNR and embodiments that involve aspects defined by 3rd Generation Partnership Project (3GPP). However, it is contemplated that embodiments relating to other wireless networking technologies are encompassed within the scope of the present disclosure.

[0046] The following description provides further details of examples of network nodes. In a 5G NR network, a gNodeB (also known as gNB) may include, e.g., a node that provides new radio (NR) user plane and control plane protocol terminations towards the UE and that is connected via a NG interface to the 5G core (5GC), e.g., according to 3GPP TS 38.300 V16.6.0 (2021-06) section 3.2, which is hereby incorporated by reference herein.

[0047] A gNB supports various protocol layers, e.g., Layer 1 (LI) - physical layer, Layer 2 (L2), and Layer 3 (L3).

[0048] The layer 2 (L2) of NR is split into the following sublayers: Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP) and Service Data Adaptation Protocol (SDAP), where, e.g. :o The physical layer offers to the MAC sublayer transport channels; o The MAC sublayer offers to the RLC sublayer logical channels;o The RLC sublayer offers to the PDCP sublayer RLC channels;o The PDCP sublayer offers to the SDAP sublayer radio bearers;o The SDAP sublayer offers to 5GC quality of service (QoS) flows; o Control channels include broadcast control channel (BCCH) and physical control channel (PCCH).

[0049] Layer 3 (L3) includes, e.g., radio resource control (RRC), e.g., according to 3GPP TS 38.300 V16.6.0 (2021-06) section 6, which is hereby incorporated by reference herein.

[0050] A gNB central unit (gNB-CU) includes, e.g., a logical node hosting, e.g., radio resource control (RRC), service data adaptation protocol (SDAP), and packet data convergence protocol (PDCP) protocols of the gNB or RRC and PDCP protocols of the en-gNB, that controls the operation of one or more gNB distributed units (gNB-DUs). The gNB-CU terminates the Fl interface connected with the gNB-DU. A gNB-CU may also be referred to herein as a CU, a central unit, a centralized unit, or a control unit.

[0051] A gNB Distributed Unit (gNB-DU) includes, e.g., a logical node hosting, e.g., radio link control (RLC), media access control (MAC), and physical (PHY) layers of the gNB or en-gNB, and its operation is partly controlled by the gNB-CU. One gNB-DU supports one or multiple cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the Fl interface connected with the gNB-CU. A gNB-DU may also be referred to herein as DU or a distributed unit.

[0052] A gNB-CU-Control Plane (gNB-CU-CP) includes, e.g., a logical node hosting, e.g., the RRC and the control plane part of the PDCP protocol of the gNB-CU for an en-gNB or a gNB. The gNB-CU-CP terminates the El interface connected with the gNB-CU-User Plane (gNB-CU-UP) and the Fl-C interface connected with the gNB-DU.

[0053] A gNB-CU-User Plane (gNB-CU-UP) includes, e.g., a logical node hosting, e.g., the user plane part of the PDCP protocol of the gNB-CU for an en-gNB, and the user plane part of the PDCP protocol and the SDAP protocol of the gNB-CU for a gNB. The gNB-CU-UP terminates the El interface connected with the gNB-CU-CP and the Fl-U interface connected with the gNB-DU, e.g., according to 3GPP TS 38.401 V16.6.0 (2021-07) section 3.1, which is hereby incorporated by reference herein.

[0054] As used herein, the term “network node” may refer to any of a gNB, a gNB-CU, a gNB-DU, a gNB-CU-CP, or a gNB-CU-UP, or any combination of them.

[0055] A RAN (radio access network) node or network node such as, e.g., a gNB, gNB-CU, or gNB-DU, or parts thereof, may be implemented using, e.g., an apparatus with at least one processor and / or at least one memory with processor-readable instructions (“program”) configured to support and / or provision and / or process CU and / or DU related functionalityand / or features, and / or at least one protocol (sub-)layer of a RAN (radio access network), e.g., layer 2 and / or layer 3. Different functional splits between the central and distributed unit are possible. An example of such an apparatus and components will be described in connection with FIG. 4 below.

[0056] The gNB-CU and gNB-DU parts may, e.g., be co-located or physically separated. The gNB-DU may even be split further, e.g., into two parts, e.g., one including processing equipment and one including an antenna. A central unit (CU) may also be called baseband unit / radio equipment controller / cloud-RAN / virtual-RAN (BBU / REC / C-RAN / V-RAN), open-RAN (O-RAN), or part thereof. A distributed unit (DU) may also be called remote radio head / remote radio unit / radio equipment / radio unit (RRH / RRU / RE / RU), or part thereof. Hereinafter, in various example embodiments of the present disclosure, a network node, which supports at least one of central unit functionality or a layer 3 protocol of a radio access network, may be, e.g., a gNB-CU. Similarly, a network node, which supports at least one of distributed unit functionality or a layer 2 protocol of the radio access network, may be, e.g., a gNB-DU.

[0057] A gNB-CU may support one or multiple gNB-DUs. A gNB-DU may support one or multiple cells and, thus, could support a serving cell for a user equipment (UE) or support a candidate cell for handover, dual connectivity, and / or carrier aggregation, among other procedures.

[0058] The user equipment (UE) 150 may be or include a wireless or mobile device, an apparatus with a radio interface to interact with a RAN (radio access network), a smartphone, an in-vehicle apparatus, an loT device, or a M2M device, among other types of user equipment. Such UE 150 may include: at least one processor; and at least one memory including program code; where the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform certain operations, such as, e.g., RRC connection to the RAN. An example of components of a UE will be described in connection with FIG. 4. In embodiments, the UE 150 may be configured to generate a message (e.g., including a cell ID) to be transmitted via radio towards a RAN (e.g., to reach and communicate with a serving cell). In embodiments, the UE 150 may generate and transmit and receive RRC messages containing one or more RRC PDUs (packet data units). Persons skilled in the art will understand RRC protocol as well as other procedures a UE may perform.

[0059] With continuing reference to FIG. 1, in the example of a 5G NR network, the network system 100 provides one or more cells, which define a coverage area of the network system 100. As described above, the network system 100 may include a gNB of a 5G NR network or may include any other apparatus configured to control radio communication andmanage radio resources within a cell. As used herein, the term “resource” may refer to radio resources, such as a resource block (RB), a physical resource block (PRB), a radio frame, a subframe, a time slot, a sub-band, a frequency region, a sub-carrier, a beam, etc. In embodiments, the network node 120 may be called a base station.

[0060] FIG. 1 provides an example and is merely illustrative of a network system 100 and a UE 150. Persons skilled in the art will understand that the network system 100 includes components not illustrated in FIG. 1 and will understand that other user equipment may be in communication with the network system 100.

[0061] FIG. 2 is a block diagram of example components of the network system 100 of FIG. 1. A 5GNR network may be described as an example of the network system 100, and it is intended that aspects of the following description shall be applicable to other types of network systems, as well. The network system may operate in accordance with the signals and connections shown in FIG. 1 such that the UE 150 is in communication with the network system 100 through the radio access network (RAN) 225. Additionally, the network system may be divided into user plane components and functions and control plane components and functions, as shown and described herein. Unless indicated otherwise, the terms “component”, “function”, and “service” may be used interchangeably herein, and they may refer to and be implemented by instructions executed by one or more processors.

[0062] Example functions of the components are described below. The example functions are merely illustrative, and it shall be understood that additional operations and functions may be performed by the components described herein. Additionally, the connections between components may be virtual connections over service-based interfaces such that any component may communicate with any other component. In this manner, any component may act as a service “producer,” for any other component that is a service “consumer,” to provide services for network functions.

[0063] For example, a core network 210 is described in the control plane of the network system. The core network 210 may include an authentication server function (AUSF) 211, an access and mobility management function (AMF) 212, and a session management function (SMF) 213. The core network 210 may also include a network slice selection function (NSSF) 214, a network exposure function (NEF) 215, a network repository function (NRF) 216, and a unified data management function (UDM) 217, which may include a uniform data repository (UDR) 224.

[0064] Additional components and functions of the core network 210 may include an application function (AF) 218, policy control function (PCF) 219, network data analyticsfunction (NWDAF) 220, analytics data repository function (ADRF) 221, management data analytics function (MDAF) 222, and operations and management function (0AM) 223.

[0065] The user plane includes the UE 150, a radio access network (RAN) 225, a user plane function (UPF) 226, and a data network (DN) 227. The RAN 225 may include one or more components described in connection with FIG. 1, such as one or more network nodes. However, the RAN 225 may not be limited to such components. The UPF 226 provides connection for data being transmitted over the RAN 225. The UPF 226 identifies services from service providers, Internet access, and third party services, for example.

[0066] The AMF 212 processes connection and mobility tasks. The AUSF 211 receives authentication requests from the AMF 212 and interacts with UDM 217 to authenticate and validate network responses for determination of successful authentication. The SMF 213 conducts packet data unit (PDU) session management, as well as manages session context with the UPF 226.

[0067] The NSSF 214 may select a network slicing instance (NSI) and determine the allowed network slice selection assistance information (NSSAI). This selection and determination is utilized to set the AMF 212 to provide service to the UE 150. The NEF 215 secures access to network services for third parties to create specialized network services. The NRF 216 acts as a repository to store network functions to allow the functions to register with and discover each other.

[0068] The UDM 217 generates authentication vectors for use by the AUSF 211 and AMF 212 and provides user identification handling. The UDM 217 may be connected to the UDR 224 which stores data associated with authentication, applications, or the like. The AF 218 provides application services to a user (e.g., streaming services, etc.). The PCF 219 provides policy control functionality. For example, the PCF 219 may assist in network slicing and mobility management, as well as provide quality of service (QoS) and charging functionality.

[0069] The NWDAF 220 collects data (e.g., from the UE 150 and the network system) to perform network analytics and provide insight to functions that utilize the analytics in the providing of services. The ADRF 221 allows the storage, retrieval, and removal of data and analytics by consumers. The MDAF 222 provides additional data analytics services for network functions. The 0AM 223 provides provisioning and management processing functions to manage elements in or connected to the network (e.g., UE 150, network nodes, etc.).

[0070] FIG. 2 is merely an example of components of a network system, and variations are contemplated to be within the scope of the present disclosure. In embodiments, the network system may include other components not illustrated in FIG. 2. In embodiments, the networksystem may not include every component illustrated in FIG. 2. In embodiments, the components and connections may be implemented with different connections than those illustrated in FIG. 2. Such and other embodiments are contemplated to be within the scope of the present disclosure.

[0071] As mentioned above, in accordance with aspects of the present disclosure, the present disclosure relates to avoiding unwanted Radio Link Failure (RLC) triggering by the RLC layer.

[0001] The present disclosure solves the technical problem of wasting radio resources due to unnecessary RLC retransmissionat same time to avoid unwanted RLF triggers when maximum number of RLC retransmission (maxRetxThreshold) is configured to lower values to match t-reordering timer for latency critical applications.

[0072] In a 5G network, the in-order delivery of a packet is performed by the PDCP layer. The reordering mechanism basically buffers a received SDU and does not forward it to higher layers until all lower-numbered SDUs have been delivered. Once a missed packet is detected by the PDCP entity, the PDCP entity starts a t-reordering timer, and until this timer has expired, the PDCP entity waits for the missed packets to be recovered by the RLC ARQ retransmission mechanism. The RLC entity recovers the missed packets by sending its status report to the transmitter entity. The packets recovered after the t-reordering timer expiry are discarded by the PDCP entity. For each retransmission of a packet by the transmitting RLC entity, the retransmission counter is incremented, which, when it reaches the limit ‘maxRetxThreshold’, configured by the gNB, triggers radio link failure (RLF).

[0073] With small values of the t-reordering timer, it is not optimal behavior to have a large ‘maxRetxThreshold’ value configured at the RLC layer. Once the t-reordering timer is expired at PDCP, the PDCP window is moved forward, and the missed packets recovered by RLC after the movement of the PDCP window will be discarded by PDCP (due to out-of-window). This would cause a waste of radio resources due to unnecessary RLC retransmission. Due to such unnecessary retransmission, there would be a delay in transmitting new packets, which increases the end to end latency of the new packets. On the other hand, if such applications are configured with a small ‘maxRetxThreshold’ value, then this would cause RLF to be triggered much frequently and early (once there are ‘maxRetxThreshold’ number of RLC retransmissions for a packet). So, there is a high probability that even for UE’s not in the poor coverage or no real issue in RLC retransmission could end up triggering very often RLF procedure. This RLF causes aLayer 3 (L3) (e.g., RRC) procedure to be triggered for a recovery. As this is a costly and time-consuming procedure, unnecessarily invoking such a RLF procedure for only a few numbers of RLC packet retransmissions would not only cause signaling overhead but also unwanted delay, increasing the latency of packets. In summary, currently, it is not possible for bearers which has a small value of t-reordering timer configured not to waste radio resources and at the same time to avoid unnecessary RLF triggers (RLF will only increase the latency of packets). The systems and methods of this disclosure solve this problem.

[0074] FIG. 3 is a diagram illustrating the RLF triggering mechanism of FIG. 8 using sliding (overlapping) windows. The diagram of FIG. 3 is based on a sliding window mechanism, where each cell indicates a number of packets reaching maxRetxThreshold transmissions in a particular time duration. During the W5 window, the total number of packets reaching maxRetxThreshold retransmission reaches maxRetxPackets. RLC may inform the higher layers, which may further initiate the RLF procedure. The configuration illustrated in FIG. 3 and FIG. 4 includes:

[0075] maxRetxPackets 3

[0076] maxRe txPacke tsDetectDuration : 5ms

[0077] maxRetxThreshold 1

[0078] FIG. 4 is a diagram illustrating the RLF triggering mechanism of FIG8 using a non-overlapping window. At the end of window W3, the RLC enitity may indicate to the RRC layer to trigger the RLF procedure.

[0079] FIG. 5 is a diagram illustrating an example of using MAC Control Element (MAC CE) to reconfigure maxRetxPackets. The MAC CE structure of FIG. 5 may be used to dynamically reconfigure maxRetxPackets parameter. A similar structure may be used to reconfigure maxRetxPacketsDetectDuration, maxNackPackets. maxNackPacketsDetectDuration, maxMissedpackets. and / or missPacketDetectionDuration. Logical channel ID (LCID): The configured value from the reserved LCID pool list to detect the MAC CE is used to dynamically reconfigure the maxRetxPackets parameter. Data Radio Bearer (DRB): the Data Radio Bearer identity for which the parameters are reconfigured. maxRetxPackets: indicate the updated maxRetxPackets value.

[0080] FIG. 6 is a diagram illustrating an example of using MAC CE for UE to indicate network node detected missed packets at PDCP. This MAC CE is configured to enable the network node (gNB) to optimize the configuration to reduce packet loss. For example, the network can increase or reduce the frequency of RLC status reporting to recover themissed packets faster, configuring the UE for handover (HO) and / or enabling duplication of packets.

[0081] FIG. 7 is a diagram of example operations for the RLF triggering mechanism at Layer 2 (L2), where the triggering is at either a transmitting RLC entity, a receiving RLC entity, or a receiving PDCP entity. The operations of FIG. 7 is performed by components that include, a user equipment (UE) and one or more network apparatus (e.g., network node, gNB). Such components may be, for example, the same components described in connection with FIG. 1 and FIG. 2 or otherwise described above.

[0082] At operation 701, the RLC entities and / or PDCP entities are configured. The RLC entities may be a UE and / or a gNB. The PDCP entities may be a UE and / or a gNB.

[0002] At operation 702, the transmitter RLC entity determines whether new parameters are configured. In aspects, the receiver PDCP entity may determine whether new parameters are configured. The parameters include maxRetxPackets, maxMissedPackets, and / or MaxNackPackets. If the new parameters are not configured, at operation 703, the transmitter RLC entity may follow an existing approach, e.g., L2 triggered RLF is determined by the retransmission count (RETX COUNT) only. For example, the gNB may be the receiver RLC entity and the UE may be the transmitter RLC entity. In another example, the UE may be the receiver RLC entity, and the gNB may be the transmitter RLC entity.

[0083] Based on the receiver RLC entities status report, packets indicated as NACK are re-transmitted by the transmitter RLC entity. For such re-transmitted packets, the retransmission count (RETX_COUNT) is incremented (as specified in 5GNR).

[0084] At operation 704, when the field “maxRetxPackets” is configured by the RRC layer for an RLC entity, the RLC entity counts the number of packets that have reached ‘maxRetxThreshold’ retransmission. In aspects, the field “maxRetxPackets” may be defined in the specification.

[0085] At operation 707, the transmitter RLC entity starts RLF detection.

[0086] At operation 710, the transmitter RLC entity determines the number of consecutive packets that have reached the maxRetxThreshold value.

[0087] If the number of consecutive packets that perform ‘ maxRetxThreshold’ retransmission reaches maxRetxPackets, the transmitter RLC entity indicates the higher layers (RRC). At operation 713, the RRC layer triggers RLF procedure based on the number of consecutive packets that perform ‘ maxRetxThreshold’ retransmission reaches maxRetxPackets.

[0088] In aspects, ‘maxRetxThreshold’ may be configured at the transmitter RLC entity and also be configured / known to the receiver RLC entity.

[0089] In aspects, the receiver RLC entity may limit the NACK for a packet to a value of ‘ maxRetxThreshold’ times. Once this limit is reached, the RLC receiver window moves its lower bound (indicated by e.g., RX_NEXT) to the first missed packet greater than the current RX_NEXT for which the status is reported as NACK < maxRetxThreshold times.

[0090] At operation 705, RLF is triggered by the receiver PDCP entity. At operation 708, the receiver PDCP entity starts RLF detection. At operation 711, the receiver PDCP entity determines if the consecutive number of missed packets within reordering window exceeds a threshold value upon t-reordering expiry.

[0003] For example, when missed packet is detected by the receiver PDCP entity, t-reordering timer is started (same as the behavior specified in 5G NR). When the receiver PDCP entity is configured with the parameter ‘ maxMissedpackets ’ by the RRC layer, upon expiry of t-reordering timer, the receiver PDCP entity counts the number of missed packets (e.g., with MISS_PKT_CNT) within the t-reordering window. In case the consecutive missed packets reach maxMissedpackets limit, the receiver PDCP entity indicates that the RRC layer takes appropriate action (e.g., triggering RLF). For downlink (DL) data, the UE may also assist the network when the network starts detecting missed packets (« maxMissedpackets) due to t-reordering expiry. This may be indicated using MAC control element (CE) using a configured LCID value (FIG 6).

[0004] At operation 706 the RLF is triggered by the receiver RLC entity. At operation 709 the receiver RLC entity starts RLF detection. At operation 712, the receiver RLC entity determines if consecutive maxNackPackets is indicated as NACK for maxRetxThreshold times.

[0091] The above-noted features provide the technical benefit of flexibility for uplink and downlink, where RLF can be configured to be triggered either or both on the transmitter and receiver side. Based on the prior indications based on the proposed MAC CE’s, before RLF conditions are met, the network can take appropriate actions to avoid RLF by dynamic change in the configuration (for example, enabling duplication and / or increasing periodicity of RLC status reports.)

[0092] The above-noted features provide flexibility to configure maxRetxThreshold value (RLC maximum retransmission) value according to t-reordering value without triggering un-necessary RLF’s.

[0093] The operations of FIG. 7 are merely examples, and variations are contemplated to be within the scope of the present disclosure. In embodiments, the operations may include others not illustrated in FIG. 7. In embodiments, the operations may not include every operation illustrated in FIG. 7. In embodiments, the operations may be implemented in a different order than that illustrated in FIG. 7. Such and other embodiments are contemplated to be within the scope of the present disclosure.

[0094] The following describes operations from the perspective of a UE. From such a perspective, a method may include: configuring transmitter Radio Link Control (RLC) entity with at least one threshold parameter to trigger Radio Link Failure (RLF) based on the at least one threshold parameter (e.g., FIG. 7, operation 702); and determining by the transmitter RLC entity to trigger RLF based on the at least one threshold parameter, wherein the threshold is related to an RLC retransmission threshold (e.g., FIG. 7, operation 704).

[0095] The following describes operations from the perspective of a network apparatus. From such a perspective, a method may include: configuring a receiver Radio Link Control (RLC) entity with at least one threshold parameter to trigger Radio Link Failure (RLF) based on the at least one threshold parameter (e.g., FIG. 7, operation 702); and determining by the receiver RLC entity to trigger RLF based on the at least one threshold parameter (e.g., FIG. 7, operation 706).

[0096] FIG. 8 is a diagram of example operations for the RLF triggering mechanism at Layer 2 where the triggering is at either a transmitting RLC entity, a receiving RLC entity, or a receiving PDCP entity, using the windowing illustrated in FIGS. 3 and 4. The operations of FIG. 8 is performed by components that include a user equipment (UE) and one or more network apparatus (e.g., network node, gNB). Such components may be, for example, the same components described in connection with FIG. 1 and FIG. 2 or otherwise described above.

[0097] Operations 801-804 and 807 of FIG. 8 are similar to operations 701-704 and 707 of FIG. 7.

[0098] Operations 804, 807, 810 illustrate a window-based mechanism for triggering RLF. At operation 810, the transmitter RLC entity determines, during a configurable window duration (maxRetxPacketsDetectDuration, which is a parameter configured by RRC), if the number of packets re-transmitted for ‘ maxRetxThreshold’ times is greater than the parameter ‘ maxRetxPackets

[0099] For example, when the parameter ‘ maxRetxPackets’ is configured by the RRC layer for a transmitter RLC entity, the transmitter RLC entity counts the number of packet that have reached ‘maxRetxThreshold’ retransmission. The transmitter RLC entity transmits a message to inform higher layers (RRC), that the count reached maxRetxPackets limit within the configurable window duration. The receiver RLC entity limits the NACK for a packet to ‘ maxRetxThreshold'’ times. Once this limit is reached, the RLC receiver window moves the lower bound (e.g., indicated by RX_NEXT) to the first missed packet greater than the current RX_NEXT for which the status is reported as NACK < maxRetxThreshold times.

[0100] Operations 805, 808, and 811 illustrate a solution where RLF is detected by the receiver PDCP entity instead of the transmitter RLC entity. At operation 805, RLF is triggered by the receiver PDCP entity.

[0101] At operation 808, the receiver PDCP entity starts RLF detection.

[0102] At operation 811, the receiver PDCP entity determines if during the last missPacketDetection period, if a number of missed packets is greater than the maxMissedpackets value.

[0005] Operations 806, 809, and 812 illustrate a solution where RLF is detected by the receiver RLC entity using a window-based mechanism similar to the window shown FIGS.3 and 4.

[0103] At operation 812, the receiver RLC entity determines, during the last configurable window duration period (maxNackPacketsDetectDuratiori), if the number of NACK’ed packets for ‘ maxRetxThreshold’ is greater than the parameter ‘ maxNackPackets ’.

[0006] For example, when “maxNackPackets” is configured by the RRC layer for an RLC entity, the RLC entity counts the number of packets that have reached ‘ maxRetxThreshold’ (configured by the RRC layer with the same value at both transmitter and receiver RLC) retransmission. The RLC entity informs higher layers (RRC), if the count reaches maxNackPackets limit within the configurable window duration maxRetxPacketsDetectDuration, (new parameter configured by the RRC layer). A similar MAC CE structure as FIG. 5, may be used to reconfigure maxNackPackets dynamically. The receiver RLC entity limits the NACK for a packet to ‘ maxRetxThreshold'’ times. Once this limit is reached, the RLC receiver window moves the lower bound (e.g., indicated by RX_NEXT) to the first missed packet greater than the current RX_NEXT for which the status is reported as NACK < maxRetxThreshold times.

[0104] The operations of FIG. 8 are merely examples, and variations are contemplated to be within the scope of the present disclosure. In embodiments, the operations may include others not illustrated in FIG. 8. In embodiments, the operations may not include every operation illustrated in FIG. 8. In embodiments, the operations may be implemented in a different order than that illustrated in FIG. 8. Such and other embodiments are contemplated to be within the scope of the present disclosure.

[0105] The following describes operations from the perspective of a UE. From such a perspective, a method may include: configuring a user equipment (UE) supporting a Packet Data Convergence Protocol (PDCP), with at least one threshold parameter to trigger Radio Link Failure (RLF) based on the at least one threshold parameter (e.g., FIG. 8, operation 801); and determining, by the UE, triggering RLF based on the at least one threshold parameter (e.g., FIG. 8, operations 802-812).

[0106] The following describes operations from the perspective of a network apparatus. From such a perspective, a method may include: configuring a network node supporting a Packet Data Convergence Protocol (PDCP), with at least one threshold parameter to trigger Radio Link Failure (RLF) based on the at least one threshold parameter (e.g., FIG.8, operation 801); and determining, by the network node, to trigger RLF based on the at least one threshold parameter (e.g., FIG. 8, operations 802-812).

[0107] Referring now to FIG. 9, there is shown a block diagram of example components of a UE or a network apparatus. The apparatus includes an electronic storage 910, a processor 920, a memory 950, and a network interface 940. The various components may be communicatively coupled with each other. The processor 920 may be and may include any type of processor, such as a single-core central processing unit (CPU), a multi-core CPU, a microprocessor, a digital signal processor (DSP), a System-on-Chip (SoC), or any other type of processor. The memory 950 may be a volatile type of memory, e.g., RAM, or a non-volatile type of memory, e.g., NAND flash memory. The memory 950 includes processor-readable instructions that are executable by the processor 920 to cause the apparatus to perform various operations, including those mentioned herein, such as the operations of FIGS. 7 and 8.

[0108] The electronic storage 910 may be and include any type of electronic storage used for storing data, such as hard disk drive, solid state drive, and / or optical disc, among other types of electronic storage. The electronic storage 910 stores processor-readable instructions for causing the apparatus to perform its operations and stores data associated with such operations, such as storing data relating to 5G NR standards, among other data. The network interface 940may implement wireless networking technologies such as 5G NR and / or other wireless networking technologies.

[0109] The components shown in FIG. 9 are merely examples, and persons skilled in the art will understand that an apparatus includes other components not illustrated and may include multiples of any of the illustrated components. Such and other embodiments are contemplated to be within the scope of the present disclosure.

[0110] Further embodiments of the present disclosure include the following examples.

[0111] Example 1.1. A user equipment (UE), comprising:means for configuring a transmitter Radio Link Control (RLC) entity with at least one threshold parameter to trigger Radio Link Failure (RLF) based on the at least one threshold parameter; andmeans for determining by the transmitter RLC entity to trigger RLF based on the at least one threshold parameter, wherein the threshold is related to an RLC retransmission threshold.

[0112] Example 1.2 The UE of Example 1.1, wherein the RLF triggering happens at the transmitter RLC entity, and wherein the at least one threshold parameter is related to a number of times the retransmissions of a at least one of RLC Service Data Units (SDU) have reached the RLC retransmission threshold.

[0113] Example 1.3 The UE of Example 1.2, further comprising:means for determining, by the transmitter RLC entity, to trigger RLF, that a number of retransmissions for at least one RLC SDUs reaches the RLC retransmission threshold and that a count of the number of packets reached the RLC retransmission threshold.

[0114] Example 1.4 The UE of any of Examples 1.2 or 1.3, further comprising determining, by the transmitter RLC entity, the triggering of RLF based on whether a number of consecutive number of retransmissions reaches a configured threshold of the at least one threshold parameter.

[0115] Example 1.5 The UE of Example 1.4, wherein the transmitter RLC entity is further configured with a configured window duration, andwherein the UE further comprises:means for determining, by the transmitter RLC entity, triggering of RLF based on a number of the number of retransmitted RLC SDUs meeting or exceeding the threshold of the at least one threshold parameter within the configured duration.

[0116] Example 1.6 The UE of Example 1.1, wherein the least one threshold parameter is configured via radio resource control (RRC) or medium access control control element (MAC CE).

[0117] Example 1.7 The UE of any of Examples 1.1 to 1.6, further comprising:means for receiving, by the transmitter RLC entity from a receiver RLC entity, a negative acknowledgement (NACK) up to a number of times equal to a threshold value, the threshold relating to a maximum number of times the retransmission of at least one RLC SDUs;means for receiving, by the transmitter RLC entity from the receiver RLC entity, an acknowledgement (ACK) in a subsequent RLC status report; andmeans for causing the receiver RLC entity to update a receiver state variable and causing the transmitter RLC entity to update the transmitter state variable,wherein the transmitter RLC entity and the receiver RLC entity are configured with a same value for the threshold value relating to a number of times the retransmission and NACKs of at least one RLC SDUs.

[0118] Example 1.8 The UE of Example 1.5, wherein the configured window duration is:a sliding window with overlapping time durations between different durations, ora non-overlapping time between different window durations.

[0119] Example 1.9 The UE of Example 1.5, wherein once the threshold is reached, a lower bound of a RLC receiver window is moved to a first missed packet greater than a current lower bound for which a status is reported as NACK less than maximum retransmission threshold times.

[0120] Example 1.10 The UE of Example 1.1, wherein the transmitter RLC entity includes a user equipment (UE) or a network node.

[0121] Example 1.13 A user equipment (UE), comprising:means for configuring the receiver Radio Link Control (RLC) entity with at least one threshold parameter to trigger Radio Link Failure (RLF) based on the at least one threshold parameter; andmeans for determining by the receiver RLC entity to trigger RLF based on the at least one threshold parameter.

[0122] Example 1.14 The UE of Example 1.13, wherein the at least one threshold parameter is related to an RLC retransmission threshold.

[0123] Example 1.15 The UE of Example 1.13, wherein the least one threshold parameter is configured via radio resource control (RRC) or medium access control control element (MAC CE).

[0124] Example 1.16 The UE of Example 1.13, further comprising:means for performing, by the receiver RLC entity the RLF triggering, wherein the threshold parameter is related to a number of times Negative Acknowledgments (NACK) for at least one RLC Service Data Units (SDUs) in RLC status reports have reached the RLC retransmission threshold.

[0125] Example 1.17 The UE of Example 1.16, further comprising:means for determining by the receiver RLC entity, to trigger RLF, based on a number of NACKs for an RLC SDU reaches the RLC retransmission threshold and that a count of the packets reaches a threshold of the at least one threshold parameter.

[0126] Example 1.18 The UE of Example 1.16, further comprising:means for determining by the receiver RLC entity, triggering of RLF based on the number of consecutive occurrences of such situations meets or exceeds the threshold of the at least one threshold parameter.

[0127] Example 1.19 The UE of Example 1.13, wherein the receiver RLC entity is further configured with a configured window duration, andwherein the UE further comprises:means for determining by the receiver RLC entity, triggering of RLF based on a number of such occurrences meeting or exceeding the configured threshold within the configured duration.

[0128] Example 1.20 The UE of Example 1.16, further comprising:means for considering by the receiver RLC entity, an RLC SDU of the at least one RLC SDUs has been received based on NACKs for the RLC SDU in RLC status reports have reached the RLC retransmission threshold.

[0129] Example 1.21 The UE of Example 1.16, further comprising:means for transmitting, by the receiver RLC entity to the transmitter RLC entity, a NACK a number of times equal to a threshold value, the threshold relating to number of times the retransmission of at least one RLC SDUs;means for transmitting, by the receiver RLC entity to the transmitter RLC entity, an ACK for the at least one RLC SDUs in subsequent RLC status report; andmeans for updating a state variable of the receiver RLC entity,wherein the transmitter RLC entity and the receiver RCL entity are configuredwith a same value for the threshold value relating to a number of times the retransmission and NACK of at least one RLC SDUs.

[0130] Example 1.22 The UE of Example 1.13, wherein the receiver RLC entity includes a user equipment (UE) or a network node.

[0131] Example 1.23 The UE of Example 1.13, wherein the configured window duration is:a sliding window with overlapping time durations between different durations, ora non-overlapping time between different window durations.

[0132] The embodiments and aspects disclosed herein are examples of the present disclosure and may be embodied in various forms. For instance, although certain embodiments herein are described as separate embodiments, each of the embodiments herein may be combined with one or more of the other embodiments herein. Specific structural and functional details disclosed herein are not to be interpreted as limiting, but as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure. Like reference numerals may refer to similar or identical elements throughout the description of the figures.

[0133] The phrases “in an aspect,” “in aspects,” “in various aspects,” “in some aspects,” or “in other aspects” may each refer to one or more of the same or different aspects in accordance with this present disclosure. The phrase “a plurality of’ may refer to two or more.

[0134] The phrases “in an embodiment,” “in embodiments,” “in various embodiments,” “in some embodiments,” or “in other embodiments” may each refer to one or more of the same or different embodiments in accordance with the present disclosure. A phrase in the form “A or B” means “(A), (B), or (A and B).” A phrase in the form “at least one of A, B, or C” means “(A); (B); (C); (A and B); (A and C); (B and C); or (A, B, and C) ”

[0135] Any of the herein described methods, programs, algorithms or codes may be converted to, or expressed in, a programming language or computer program. The terms “programming language” and “computer program,” as used herein, each include any language used to specify instructions to a computer, and include (but is not limited to) the following languages and their derivatives: Assembler, Basic, Batch files, BCPL, C, C+, C++, Delphi, Fortran, Java, JavaScript, machine code, operating system command languages, Pascal, Perl, PL1, Python, scripting languages, Visual Basic, metalanguages which themselves specify programs, and all first, second, third, fourth, fifth, or further generation computer languages. Also included are database and other data schemas, and any other meta-languages. Nodistinction is made between languages which are interpreted, compiled, or use both compiled and interpreted approaches. No distinction is made between compiled and source versions of a program. Thus, reference to a program, where the programming language could exist in more than one state (such as source, compiled, object, or linked) is a reference to any and all such states. Reference to a program may encompass the actual instructions and / or the intent of those instructions.

[0136] While aspects of the present disclosure have been shown in the drawings, it is not intended that the present disclosure be limited thereto, as it is intended that the present disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular aspects. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.

Claims

WE CLAIM:

1. A method, comprising:configuring a transmitter Radio Link Control (RLC) entity with at least one threshold parameter to trigger Radio Link Failure (RLF) based on the at least one threshold parameter; anddetermining by the transmitter RLC entity to trigger RLF based on the at least one threshold parameter, wherein the threshold is related to an RLC retransmission threshold.

2. The method of claim 1, wherein the RLF triggering happens at the transmitter RLC entity, and wherein the at least one threshold parameter is related to a number of times the retransmissions of a at least one of RLC Service Data Units (SDU) have reached the RLC retransmission threshold.

3. The method of claim 2, further comprising:determining, by the transmitter RLC entity, to trigger RLF, that a number of retransmissions for at least one RLC SDUs reaches the RLC retransmission threshold and that a count of the number of packets reached the RLC retransmission threshold.

4. The method of claims 2 or 3, further comprising:determining, by the transmitter RLC entity, the triggering of RLF based on whether a number of consecutive number of retransmissions reaches a configured threshold of the at least one threshold parameter.

5. The method of claim 4, wherein the transmitter RLC entity is further configured with a configured window duration, andwherein the method further comprises:determining, by the transmitter RLC entity, triggering of RLF based on a number of the number of retransmitted RLC SDUs meeting or exceeding the threshold of the at least one threshold parameter within the configured duration.

6. The method of claim 1, wherein the least one threshold parameter is configured via radio resource control (RRC) or medium access control control element (MAC CE).

7. The method of any of the preceding claims, further comprising:receiving, by the transmitter RLC entity from a receiver RLC entity, a negative acknowledgement (NACK) up to a number of times equal to a threshold value, the threshold relating to a maximum number of times the retransmission of at least one RLC SDUs;receiving, by the transmitter RLC entity from the receiver RLC entity, an acknowledgement (ACK) in a subsequent RLC status report; andcausing the receiver RLC entity to update a receiver state variable and causing the transmitter RLC entity to update the transmitter state variable,wherein the transmitter RLC entity and the receiver RLC entity are configured with a same value for the threshold value relating to a number of times the retransmission and NACKs of at least one RLC SDUs.

8. The method of claim 5, wherein the configured window duration is:a sliding window with overlapping time durations between different durations, or a non-overlapping time between different window durations.

9. The method of claim 5, wherein once the threshold is reached, a lower bound of a RLC receiver window is moved to a first missed packet greater than a current lower bound for which a status is reported as NACK less than maximum retransmission threshold times.

10. The method of claim 1, wherein the transmitter RLC entity includes a user equipment (UE) or a network node.

11. A user equipment (UE), comprising:at least one processor; andat least one memory storing instructions which, when executed by the at least one processor, cause the UE at least to perform a method as in any one of claims 1 to 10.

12. A processor-readable medium storing instructions which, when executed by at least one processor of a user equipment (UE), cause the UE at least to perform a method as in any one of claims 1 to 10.

13. A method, comprising:configuring a receiver Radio Link Control (RLC) entity with at least one threshold parameter to trigger Radio Link Failure (RLF) based on the at least one threshold parameter; anddetermining by the receiver RLC entity to trigger RLF based on the at least one threshold parameter.

14. The method of claim 13, wherein the at least one threshold parameter is related to an RLC retransmission threshold.

15. The method of claim 13, wherein the least one threshold parameter is configured via radio resource control (RRC) or medium access control control element (MAC CE).

16. The method of claim 13, further comprising:performing, by the receiver RLC entity the RLF triggering,wherein the threshold parameter is related to a number of times Negative Acknowledgments (NACK) for at least one RLC Service Data Units (SDUs) in RLC status reports have reached the RLC retransmission threshold.

17. The method of claim 16, further comprising:determining by the receiver RLC entity, to trigger RLF, based on a number of NACKs for an RLC SDU reaches the RLC retransmission threshold and that a count of the packets reaches a threshold of the at least one threshold parameter.

18. The method of claim 16, further comprising:determining by the receiver RLC entity, triggering of RLF based on the number of consecutive occurrences of such situations meets or exceeds the threshold of the at least one threshold parameter.

19. The method of claim 13, wherein the receiver RLC entity is further configured with a configured window duration, andwherein the method further comprises:determining by the receiver RLC entity, triggering of RLF based on a number of such occurrences meeting or exceeding the configured threshold within the configured duration.

20. The method of claim 16, further comprising:considering by the receiver RLC entity, an RLC SDU of the at least one RLC SDUs has been received based on NACKs for the RLC SDU in RLC status reports have reached the RLC retransmission threshold.

21. The method of claim 16, further comprising:transmitting, by the receiver RLC entity to the transmitter RLC entity, a NACK a number of times equal to a threshold value, the threshold relating to number of times the retransmission of at least one RLC SDUs;transmitting, by the receiver RLC entity to the transmitter RLC entity, an ACK for the at least one RLC SDUs in subsequent RLC status report; andupdating a state variable of the receiver RLC entity,wherein the transmitter RLC entity and the receiver RCL entity are configured with a same value for the threshold value relating to a number of times the retransmission and NACK of at least one RLC SDUs.

22. The method of claim 13, wherein the receiver RLC entity includes a user equipment (UE) or a network node.

23. The method of claim 13, wherein the configured window duration is:a sliding window with overlapping time durations between different durations, or a non-overlapping time between different window durations.

24. A network apparatus comprising:at least one processor; andat least one memory storing instructions which, when executed by the at least one processor, cause the network apparatus at least to perform a method as in any one of claims 13 to 23.

25. A processor-readable medium storing instructions which, when executed by at least one processor of a network apparatus, causes the network apparatus at least to perform a method as in any one of claims 13 to 23.26

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