Method, apparatus and computer program for processing reconfiguration failure

Abstract

There is provided an apparatus comprising: means for receiving a reconfiguration request from a base station when the apparatus is a relay between the base station and a remote user equipment; means for determining a reconfiguration failure at the device associated with the reconfiguration request; means for generating a notification for the remote user equipment in response to determining that the reconfiguration at the apparatus fails; and means for sending a notification to a remote user device.

Description

Technical Field

[0001] Various example embodiments of the present disclosure relate to methods, apparatus, systems and computer programs. In particular and exclusively, various example embodiments relate to handling reconfiguration failure of relay user equipment. Background Art

[0002] A communication network can be considered as a facility that enables communication between two or more communication devices, or provides communication devices with access to a data network. A mobile or wireless communication network is an example of a communication network. Communication devices can be served by application servers.

[0003] Such communication networks operate according to standards such as provided by 3GPP (3rd Generation Partnership Project) or ETSI (European Telecommunications Standards Institute). An example of a standard is the so-called 5G (fifth generation) standard provided by 3GPP. Summary of the invention

[0004] Some example embodiments of the present disclosure will be described in certain aspects. These aspects are not intended to indicate the key or essential features of the embodiments of the present disclosure, nor are they intended to be used to limit the scope of the present disclosure. In view of the present disclosure, other features, aspects, and elements will be apparent to those skilled in the art.

[0005] According to a first aspect, an apparatus is provided, comprising: a component for receiving a reconfiguration request from a base station when the apparatus acts as a relay between the base station and a remote user equipment; a component for determining a reconfiguration failure at the apparatus associated with the reconfiguration request; a component for generating a notification for the remote user equipment in response to determining a reconfiguration failure at the apparatus; and a component for sending the notification to the remote user equipment.

[0006] According to some examples, the apparatus includes: means for performing a connection reestablishment procedure with the base station or another base station.

[0007] According to some examples, the means for sending the notification to the remote user equipment is configured to send the notification to the remote user equipment before performing a connection reestablishment procedure or before an outcome of a connection reestablishment procedure with the base station or another base station is known.

[0008] According to some examples, the means for sending the notification to the remote user equipment is configured to send the notification immediately or substantially immediately after determining that the reconfiguration has failed.

[0009] According to some examples, the means for generating a notification is configured to generate a notification arranged to cause a remote user equipment to not use the apparatus to perform a connection reestablishment procedure with the base station or another base station.

[0010] According to some examples, the means for sending the notification to the remote user equipment is configured to send the notification to the remote user equipment after the result of the connection reestablishment procedure with the base station or another base station is known.

[0011] According to some examples, the means for generating the notification is configured to generate the notification in a manner dependent on an outcome of a connection reestablishment procedure.

[0012] According to some examples, when the result of the connection reestablishment process is a failure of the connection reestablishment process, the component for generating a notification is configured to generate a notification, which is arranged so that the remote user equipment does not use the device to perform a connection reestablishment process for the remote user equipment and the base station or another base station.

[0013] According to some examples, when the result of the connection reestablishment process is the success of the connection reestablishment process, the component for generating a notification is configured to generate a notification, which also depends on one or more of the following items: whether there has been a cell change of the device as a result of the connection reestablishment process; whether there has been a configuration change of the remote user equipment as a result of the connection reestablishment process.

[0014] According to some examples, when the result of the connection reestablishment process is the success of the connection reestablishment process, the device for generating a notification is arranged to generate a notification, which is configured to cause the remote user equipment to perform a connection reestablishment process for the remote user equipment and the base station or another base station via the device.

[0015] According to some examples, the means for generating a notification is configured to: generate a notification indicating one of: a reconfiguration failure; or a connection reestablishment failure.

[0016] According to some examples, the means for generating a notification is configured to generate a notification indicating one of: a successful reestablishment of the connection; or a handover.

[0017] According to some examples, the apparatus includes: means for autonomous behavior; and / or the apparatus includes: means for receiving instructions from a base station instructing the apparatus how to behave.

[0018] According to some examples, the device includes: means for controlling the behavior of the device based on conditions including one or more of the following: a reason or purpose for reconfiguration of the device; a radio channel condition; a mobile state of the device; a hardware state of the device.

[0019] According to some examples, the apparatus includes a relay user equipment.

[0020] According to some examples, the component includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause execution of the device.

[0021] According to a second aspect, a device is provided, comprising: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, causes the device to at least: receive a reconfiguration request from a base station when the device acts as a relay between the base station and a remote user device; determine a reconfiguration failure at the device associated with the reconfiguration request; generate a notification for the remote user device in response to determining the reconfiguration failure at the device; and send the notification to the remote user device.

[0022] According to a third aspect, a device is provided, comprising: a circuit system for receiving a reconfiguration request from a base station when the device acts as a relay between the base station and a remote user device; a circuit system for determining a reconfiguration failure at the device associated with the reconfiguration request; a circuit system for generating a notification for the remote user device in response to determining a reconfiguration failure at the device; and a circuit system for sending the notification to the remote user device.

[0023] According to a fourth aspect, a method performed by an apparatus is provided, the method comprising: when the apparatus acts as a relay between a base station and a remote user equipment, receiving a reconfiguration request from a base station; determining a reconfiguration failure at the apparatus associated with the reconfiguration request; generating a notification for the remote user equipment in response to determining the reconfiguration failure of the apparatus; and sending the notification to the remote user equipment.

[0024] According to some examples, the method includes performing a connection reestablishment procedure with the base station or another base station.

[0025] According to some examples, the method includes sending a notification to a remote user equipment before performing a connection reestablishment procedure or before an outcome of a connection reestablishment procedure with the base station or another base station is known.

[0026] According to some examples, the method includes sending a notification to a remote user device immediately or substantially immediately after determining that the reconfiguration has failed.

[0027] According to some examples, the method includes generating a notification arranged to cause a remote user equipment not to use the apparatus to perform a connection reestablishment procedure with the base station or another base station.

[0028] According to some examples, the method includes sending a notification to a remote user equipment after a result of a connection reestablishment procedure with the base station or another base station is known.

[0029] According to some examples, the method includes generating the notification in a manner dependent on an outcome of a connection reestablishment procedure.

[0030] According to some examples, when the result of the connection reestablishment procedure is a failure of the connection reestablishment procedure, the method includes: generating a notification arranged so that the remote user equipment does not use the device to perform a connection reestablishment procedure for the remote user equipment and the base station or another base station.

[0031] According to some examples, when the result of the connection reestablishment process is the success of the connection reestablishment process, the method includes: generating a notification, which also depends on one or more of the following items: whether there has been a cell change of the device as a result of the connection reestablishment process; whether there has been a configuration change of the remote user equipment as a result of the connection reestablishment process.

[0032] According to some examples, when the result of the connection reestablishment process is a success of the connection reestablishment process, the method includes: generating a notification configured to cause the remote user equipment to perform a connection reestablishment process between the remote user equipment and the base station or another base station via the apparatus.

[0033] According to some examples, the method includes: generating a notification indicating one of: a reconfiguration failure; or a connection reestablishment failure.

[0034] According to some examples, the method includes: generating a notification indicating one of: a successful connection reestablishment; or a handover.

[0035] According to some examples, the method includes: behaving autonomously; and / or receiving instructions from a base station instructing the device how to behave.

[0036] According to some examples, the method includes: controlling the behavior of the device based on conditions including one or more of the following: the reason or purpose of the reconfiguration of the device; the radio channel condition; the mobile state of the device; the hardware state of the device.

[0037] According to some examples, the apparatus includes a relay user equipment.

[0038] According to a fifth aspect, there is provided a computer program comprising instructions, which, when executed by an apparatus, causes the apparatus to perform at least the following items: when the apparatus acts as a relay between a base station and a remote user equipment, receiving a reconfiguration request from the base station; determining a reconfiguration failure at the apparatus associated with the reconfiguration request; generating a notification for the remote user equipment in response to determining a reconfiguration failure at the apparatus; and sending the notification to the remote user equipment.

[0039] According to a sixth aspect, a non-transitory computer-readable medium comprising program instructions is provided, which, when executed by an apparatus, causes the apparatus to perform at least the following items: when the apparatus acts as a relay between a base station and a remote user device, receiving a reconfiguration request from the base station; determining a reconfiguration failure at the apparatus associated with the reconfiguration request; generating a notification for the remote user device in response to determining a reconfiguration failure at the apparatus; and sending the notification to the remote user device.

[0040] According to the seventh aspect, a device is provided, comprising: a component for receiving a notification from a relay user equipment, which acts as a relay between the device and a base station, wherein the notification is associated with a reconfiguration failure of the relay user equipment; and a component for performing a connection reestablishment process between the device and the base station or another base station in response to receiving the notification.

[0041] According to some examples, the component for performing the connection reestablishment process is configured to: perform the connection reestablishment process between the device and the base station or another base station without using the relay user equipment when the notification indicates one of the following items: failure of reconfiguration of the relay user equipment; failure of connection reestablishment of the relay user equipment.

[0042] According to some examples, the component for performing a connection reestablishment process is configured to: perform a connection reestablishment process between the device and a base station or another base station via a relay user equipment when a notification indicates one of the following items: success of connection reestablishment of the relay user equipment; switching of the relay user equipment.

[0043] According to some examples, the device includes: a component for performing a connection reestablishment procedure between the device and the base station or another base station in a manner that depends on at least one of the following items: a radio resource control state of the device; a multipath configuration of the device.

[0044] According to some examples, the apparatus includes a remote user device.

[0045] According to some examples, the component includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause execution of the device.

[0046] According to an eighth aspect, a device is provided, comprising: at least one processor; and at least one memory storing instructions, which, when the instructions are executed by the at least one processor, cause the device to at least perform: receiving a notification from a relay user equipment, which acts as a relay between the device and a base station, wherein the notification is associated with a reconfiguration failure of the relay user equipment; and in response to receiving the notification, performing a connection reestablishment process between the device and the base station or another base station.

[0047] According to a ninth aspect, a device is provided, comprising: a circuit system for receiving a notification from a relay user equipment, the relay user equipment acting as a relay between the device and a base station, wherein the notification is associated with a reconfiguration failure of the relay user equipment; and a circuit system for performing a connection reestablishment process between the device and the base station or another base station in response to receiving the notification.

[0048] According to the tenth aspect, a method performed by an apparatus is provided, the method comprising: receiving a notification from a relay user equipment, the relay user equipment acting as a relay between the apparatus and a base station, wherein the notification is associated with a reconfiguration failure of the relay user equipment; and in response to receiving the notification, performing a connection reestablishment process between the apparatus and the base station or another base station.

[0049] According to some examples, the method includes: executing a connection reestablishment process between the device and the base station or another base station without using a relay user equipment when the notification indicates one of the following items: reconfiguration of the relay user equipment fails; connection reestablishment of the relay user equipment fails.

[0050] According to some examples, the method includes: executing a connection reestablishment process between the device and the base station or another base station via a relay user equipment when the notification indicates one of the following items: successful connection reestablishment of the relay user equipment; switching of the relay user equipment.

[0051] According to some examples, the method includes: performing a connection reestablishment procedure between the device and the base station or another base station in a manner that depends on at least one of the following items: a radio resource control state of the device; a multipath configuration of the device.

[0052] According to some examples, the apparatus includes a remote user device.

[0053] According to the eleventh aspect, a computer program comprising instructions is provided, which, when executed by an apparatus, causes the apparatus to perform at least the following items: receiving a notification from a relay user equipment, the relay user equipment acting as a relay between the apparatus and a base station, wherein the notification is associated with a reconfiguration failure of the relay user equipment; and in response to receiving the notification, performing a connection reestablishment process between the apparatus and the base station or another base station.

[0054] According to the twelfth aspect, a non-transitory computer-readable medium comprising program instructions is provided, which, when executed by an apparatus, causes the apparatus to perform at least the following items: receiving a notification from a relay user equipment, the relay user equipment acting as a relay between the apparatus and a base station, wherein the notification is associated with a reconfiguration failure of the relay user equipment; and in response to receiving the notification, performing a connection reestablishment process between the apparatus and the base station or another base station. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Some example embodiments will now be described, by way of non-limiting and illustrative examples only, with reference to the accompanying drawings, in which:

[0056] Figure 1 A representation of a fifth generation communication system is shown;

[0057] Figures 2 to 6 is a signaling diagram according to some example embodiments;

[0058] Figure 7 schematically shows a representation of a control device according to some example embodiments;

[0059] Figure 8 schematically illustrates a representation of a user equipment according to some example embodiments;

[0060] Fig. 9 is a flow chart of a method according to an example embodiment;

[0061] Fig.10 is a flow chart of a method according to an example embodiment;

[0062] Fig.11 Representations of apparatuses according to some example embodiments are shown. DETAILED DESCRIPTION

[0063] In the following, various exemplary embodiments are explained with reference to a communication device capable of communicating with a communication system. Figure 1 , the fifth generation communication system (5GS) is briefly explained by way of examples.

[0064] Figure 1 A schematic representation of a 5G communication system (5GS) is shown. The 5GS may include a user equipment (UE) 100, an access network such as a 5G radio access network (5G-RAN) 102 or a next generation radio access network (NG-RAN), a 5G core network (5GC) 104, and one or more application functions 106. The application functions may be deployed in the 5GS or deployed or hosted on one or more application servers of a data network. The 5GS connects the UE to the data network, the access network, and the 5GC (e.g., the UPF of the 5GC).

[0065] 5G-RAN may include one or more radio access nodes, such as gNodeBs (gNBs). A gNB may include one or more gNB distributed units connected to one or more gNB centralized units.

[0066] 5GC 104 may include the following network functions: network slice selection function (NSSF); network exposure function 108; network repository function (NRF); policy control function (PCF); unified data management (UDM) 110; application function (AF) 106; authentication server function (AUSF) 112; access and mobility management function (AMF) 114; and session management function (SMF) 116, user plane function (UPF) 118, and data network (DN) 120. Figure 1 It is also shown that various interfaces (N1, N2, etc.) can be implemented between different elements of the system.

[0067] It should be noted that Figure 1 It is provided as an example of a communication system in which the present disclosure can be performed; however, the present disclosure is not limited to a 5G communication system. For example, the present disclosure may also be applicable to other systems such as 4G, 6G, etc.

[0068] The present disclosure relates to NR Sidelink (SL) based on Layer 2 (L2) UE to NW (U2N). More particularly, the present disclosure relates to handling of relay UE failures, or more specifically, handling of RRC reconfiguration failures of relay UEs. Release 17 specifies NR L2 U2N relay for the first time, supporting service continuity for intra-gNB direct to indirect (d2i) and indirect to direct (i2d) path switching in Layer 2 U2N relay. In some examples, relay UEs can be used to extend coverage to "remote UEs". For example, a "remote UE" can be a UE outside the coverage of the network infrastructure.

[0069] Section 5.3.5.8 of 3GPP TS38.331 documents the UE reconfiguration failure behavior in the case where the UE is "unable to comply with RRC reconfiguration", which will trigger the UE to initiate the RRC connection reestablishment procedure.

[0070] The present disclosure has identified that currently a remote UE may not know when a relay UE to which it is connected experiences a reconfiguration failure. In particular, the remote UE may not be notified when there is a reconfiguration failure in the relay UE.

[0071] As is known, the gNB may initiate an RRC reconfiguration procedure towards the UEs (including the relay UE), for example due to adding a new service / QoS flow for the Uu (UE-RAN) traffic of the relay UE itself; adding / releasing an SN (secondary node); and / or adding / releasing a remote UE connected to the relay UE. The gNB may also initiate an RRC reconfiguration procedure due to changes in network conditions, such as changes in cell load, etc. In some cases, the RRC reconfiguration cannot be accepted or decoded by the relay UE. For example, this may be due to an ASN.1 decoding error on the relay UE side, or incorrect parameters used by the gNB. In this case, the relay UE identifies an RRC reconfiguration failure, triggering the relay UE to initiate an RRC connection reestablishment procedure. When the relay UE initiates the RRC connection reestablishment procedure, the configuration related to the PC5 interface towards the remote UE is released. The reestablishment may even occur in a different cell or even a different gNB that does not have the remote UE context. Therefore, when the relay UE initiates the RRC connection reestablishment procedure, it affects the service continuity of the remote UE, which is served by the relay UE with the reconfiguration failure. For example, pending data of the remote UE will be lost or discarded without the remote UE knowing this because the remote UE is not notified when there is a reconfiguration failure in the relay UE.

[0072] In the current 3GPP specification, the remote UE does not know whether the relay UE initiates a reestablishment after the relay UE's reconfiguration fails. This is because the relay UE's reestablishment initiated due to a reconfiguration failure does not trigger a notification (e.g., NotificationMessageSidelink) to the remote UE. Therefore, the remote UE may mistakenly believe that the relay UE is operating normally when serving the remote UE. This may lead to one or more problems, such as data loss; throughput degradation; or violation of delay requirements in data transmission.

[0073] Therefore, in some examples, the present disclosure proposes a behavior of a relay UE. The behavior may include triggering the sending of a notification message to a remote UE. The notification message may be sent on a sidelink connection between the relay UE and the remote UE. For example, when the RRC reconfiguration of the relay UE fails, a sidelink notification message may be sent to the remote UE. In the example, it is assumed that a relay connection to a network (e.g., a gNB) is established for the remote UE via the relay UE. For example, the connection may be an L2 U2N connection. In some examples, the relay UE may receive an RRC reconfiguration message from the gNB configured on the relay UE. When the relay UE fails to comply with the reconfiguration, a reconfiguration failure occurs, triggering the relay UE to initiate RRC connection reestablishment. Reestablishment of the RRC connection may result in selecting the same or different cell in the same gNB, or selecting a new cell in a different gNB.

[0074] According to the present disclosure, there are two main options (Option 1 and Option 2) for the proposed relay UE behavior. Each of these options will be discussed in turn below.

[0075] Option 1

[0076] In the first option, when the specified relay UE behavior is to initiate RRC connection reestablishment when reconfiguration fails, the relay UE is configured to maintain the relay-related configuration for at least a period of time. For example, the relay UE can wait for the result of the RRC reestablishment process without releasing the relay-related configuration / entity. For example, the relay UE can delay the release, or can maintain information of one or more of the following items: sl-L2RelayUE-Config; sl-L2RemoteUE-config; and SRAP entity (where SRAP is the Sidelink Relay Adaptation Protocol). Subsequently, the relay UE can send a notification message to the remote UE. For example, the manner of sending (or not sending) the notification message to the remote UE may depend on the result of the RRC reestablishment process. For example:

[0077] (i) If the RRC reestablishment of the same cell is successful and the configuration related to the connected remote UE remains unchanged, the notification message will not be triggered; otherwise

[0078] (ii) Similar to option (i), where RRC re-establishment is successful, but triggers notification to the remote UE (e.g. relayUE-HO notification); otherwise

[0079] (iii) If the RRC re-establishment is successful to a different unit or the same unit, but the configuration in the re-established connection does not include / maintain the same configuration related to the remote UE, a notification message is sent to the remote UE using an existing indication type (e.g., relayUE-HO) or a new type of indication. Using an existing message type (e.g., relayUE-HO) in this case can minimize the changes required to implement the embodiments of the present disclosure. The relay UE releases the sl-L2RelayUE-Config, sl-L2RemoteUE-Config, and SRAP entities; otherwise (iv) If the RRC re-establishment fails, a notification message is sent to the remote UE using an existing indication type (e.g., relayUE-Uu-RRC-Failure) or a new indication type. Then, the relay UE releases one or more sl-L2RelayUE-Config; sl-L2RemoteUE-Config, and SRAP entities.

[0080] After receiving the notification from the relay UE, the remote UE then takes appropriate action depending on the notification type, whether or not the reestablishment is successful. In some examples, the action taken by the remote UE may also depend on the RRC state of the remote UE, for example, whether the remote UE is in RRC_IDLE / RRC_INACTIVE or RRC_CONNECTED state. When the remote UE is in the RRC_CONNECTED state, the action taken by the remote UE may also depend on whether the remote UE has a multipath configuration.

[0081] Figures 2 to 5 The above situations (i) to (iv) are shown in more detail respectively, where the communication between the remote UE 250, the relay UE 200 and the gNB 202 is shown.

[0082] In each of cases (i) to (iv), it is assumed that the remote UE 250 is in the RRC-CONNECTED state with the gNB 202 via the relay UE 200. Figures 2 to 5 It is shown at S201, S301, S401 and S501 in FIG.

[0083] Then, there is an RRC reconfiguration request from gNB 202. This is respectively Figures 2 to 5 For example, the reconfiguration may be related to the Uu connection of the relay UE 200 or the PC5 connection to the remote UE 250.

[0084] The present disclosure deals with the case of reconfiguration failure associated with the RRC configuration request of S202, S302, S402, S502. Therefore, the relay UE 200 determines that the reconfiguration has failed. The determined reconfiguration failure is respectively Figures 2 to 5 It is shown at S203, S303, S403, and S503.

[0085] In response to the reconfiguration failure, an RRC connection reestablishment process occurs between the relay UE 200 and the gNB 202. Figures 2 to 5 It is schematically shown at S204, S304, S404 and S504 in FIG.

[0086] According to an example, in response to determining that the reconfiguration at the relay UE has failed, the relay UE 200 can generate a notification to be sent to the remote UE 250. In some examples (described in more detail below), the notification is not sent to the remote UE 250. Therefore, in some examples, it can be considered that the relay UE can selectively generate and send a notification to the remote UE 250 depending on the situation and in response to determining that the reconfiguration has failed.

[0087] In cases (i) to (iv), relay UE 200 awaits the result of the RRC re-establishment procedure before determining (a) whether a notification should be sent to remote UE 250, and (b) what the content of the notification should be.

[0088] Case (i)

[0089] In case (i), if Figure 2 As shown, the RRC connection reestablishment process of S204 is successfully completed. As part of the RRC connection reestablishment process of S204, there is no cell change for the relay UE 200, nor any configuration change related to the remote UE 250.

[0090] Therefore, in this example, no notification is sent to the remote UE 250. This is because no change is required at the remote UE 250 and the relay connection between the remote UE 250 and the gNB 202 can continue. Therefore, the remote UE 250 does not need to receive a notification about the reconfiguration failure or the reestablishment process. This is schematically shown at S205.

[0091] In some examples of case (i), the relay UE 200 is configured to maintain one or more stored information. For example, the relay UE 200 may maintain configuration information related to one or more of the following items: side link layer 2 relay UE configuration information; side link layer 2 remote user equipment information; side link relay adaptation protocol (SRAP) information.

[0092] Scenario (ii)

[0093] In case (ii), if Figure 3 As shown at S305, the RRC connection reestablishment process is successfully completed without checking whether there is a cell change for the relay UE or a configuration change for the remote UE associated with the reestablished RRC connection. In this example, the relay UE 200 may release configuration information related to one or more of the following items: side link layer 2 relay UE configuration information; side link layer 2 remote user equipment information; side link relay adaptation protocol (SRAP) information. Or before the relay UE 200 initiates the RRC connection reestablishment process, the relay UE 200 may have released the configuration information.

[0094] At S306, the relay UE 200 sends a sidelink notification message to the remote UE 250. In some examples, it can be considered that the notification of S306 is configured to cause the remote UE 250 to perform an RRC reestablishment process with the gNB 202 (or another gNB). For example, the notification at S306 can be a relayUE-HO notification.

[0095] The performance of the RRC connection reestablishment process is shown at 307. In some examples, for example, where the relayUE-HO notification is used at S306, the RRC connection reestablishment can be performed with gNB 202 (or another gNB) via relay UE 200 (or via another relay UE).

[0096] Scenario (iii)

[0097] In case (iii), if Figure 4 As shown at S405, the RRC connection reestablishment process is successfully completed. In some examples, there may be a cell change for the relay UE 200. In other examples, there may not be a cell change for the relay UE 200. In this example, there is a change in the configuration of the remote UE 250. The relay UE 200 releases configuration information related to one or more of the following items: side link layer 2 relay UE configuration information; side link layer 2 remote user equipment information; side link relay adaptation protocol (SRAP) information.

[0098] At S406, the relay UE 200 sends a sidelink notification message to the remote UE 250. In some examples, it can be considered that the notification of S406 is configured to cause the remote UE 250 to perform an RRC reestablishment process with the gNB 202 (or another gNB). For example, the notification at S406 can be a relayUE-HO notification.

[0099] The performance of the RRC connection reestablishment process is shown at 407. In some examples, for example, where the relaye-HO notification is used at S406, the RRC connection reestablishment may be performed with the gNB 202 (or another gNB) via the relay UE 200 (or via another relay UE).

[0100] Case (iv)

[0101] In case (iv), if Figure 5 As shown at S505, the RRC connection reestablishment process fails. The relay UE 200 releases configuration information related to one or more of the following items: side link layer 2 relay UE configuration information; side link layer 2 remote user equipment information; side link relay adaptation protocol (SRAP) information.

[0102] At S506, the relay UE 200 sends a sidelink notification message to the remote UE 250. In some examples, it can be considered that the notification of S506 is configured to cause the remote UE 250 to perform an RRC reestablishment procedure with the gNB 202 (or another gNB). For example, the notification at S506 can be a relayUE-Uu-RRC-Failure notification (i.e., a notification indicating that the RRC connection reestablishment procedure at S504 failed).

[0103] The performance of the RRC connection reestablishment process is shown at S507. In some examples, for example, when relayUE-Uu-RRC-Failure is used at S506, the RRC connection reestablishment may be performed directly (i.e., not via relay UE 200 or another relay UE) with gNB 202 (or another gNB) or via another relay UE. In other words, the reestablishment of remote UE 250 is not via relay UE 200 because relay UE 200 failed to reestablish. Therefore, the remote UE may reestablish to the gNB directly or via another relay UE.

[0104] In some examples, the behavior of the remote UE 250 depends on one or both of the following: (a) the RRC state of the remote UE; (b) the multipath configuration of the remote UE. For example, the remote UE behavior may include one or more of the following:

[0105] The remote UE considers that a cell reselection occurs if the remote UE is in RRC_Idle / Inactive state and receives a relayUE-HO notification;

[0106] If the remote UE is in RRC_Connected and the T301 timer is not running, the remote UE initiates RRC connection re-establishment; and / or

[0107] If a relayUE-Uu-RRC-Failure notification is received, if the remote UE determines to release the PC5-RRC connection with the "current" relay UE, the remote UE indicates to the upper layer to trigger the release of the PC5 unicast link; or

[0108] If the remote UE is configured with multipath operation using both an indirect path and a direct path, the remote UE shall suspend transmission on the indirect path.

[0109] Option 2

[0110] In the second option, the relay UE does not wait for the RRC reestablishment process result before sending the notification message to the remote UE. In some examples, when the relay UE 200 initiates RRC connection reestablishment, for example due to a reconfiguration failure using an existing indication type (e.g., relayUE-Uu-RRC-Failure) or a new type (e.g., relayUE-Uu-RRCReconfiguration-Failure), a notification message (e.g., NotificationMessageSidelink message) is sent to the remote UE 250. In some examples, the sending of the notification message is in response to when the relay UE 200 initiates RRC connection reestablishment. In some examples, the sending of the notification message occurs immediately or substantially immediately after the relay UE initiates RRC connection reestablishment. Therefore, in some examples, it can be considered that, in response to determining a reconfiguration failure at the remote UE 250, the notification from the relay UE 200 to the remote UE 250 is sent before the RRC connection reestablishment process between the gNB 202 and the relay UE 200 is initiated or completed.

[0111] In the example, upon receiving the notification from the relay UE, the remote UE takes appropriate action. In some examples, the action taken by the remote UE depends on the RRC state of the remote UE, such as whether the remote UE is in RRC_IDLE / RRC_INACTIVE or RRC_CONNECTED state. In the latter case (i.e., RRC_CONNECTED), this may depend on having a multipath configuration (described in more detail below).

[0112] Figure 6 is a signaling diagram showing an example implementation of Option 2.

[0113] Steps S601 to S603 are similar to Figures 2 to 5 For the sake of brevity, the first three steps will not be discussed in further detail.

[0114] At S604, in response to the reconfiguration failure determined at S603, a sidelink notification message is sent from the relay UE 200 to the remote UE 250. It can be considered that the notification message is configured to cause the remote UE 250 to perform an RRC connection reestablishment procedure with the gNB 202 (or another gNB). For example, the sidelink notification may be in the form of relayUE-Uu-RRC-Failure (i.e., indicating a reconfiguration failure at the relay UE 200).

[0115] Note that the notification message at S604 is sent before the RRC connection reestablishment procedure is initiated at S605. In some examples, the notification message at S604 is sent immediately or substantially immediately after the determination at S603.

[0116] The RRC connection reestablishment process between the remote UE 250 and the gNB 202 is shown at S606. In some examples, for example, where the notification at S604 indicates that the reconfiguration of the relay UE 200 has failed, the remote UE 250 performs the RRC connection reestablishment process at S606 directly with the gNB 202 (or directly with another gNB) or via another relay UE.

[0117] Some additional features that may be common to both Option 1 and Option 2 will now be discussed.

[0118] In some examples, the connection re-establishment between the relay UE 200 and the base station may be between the base station that originally served the relay UE or another base station.

[0119] In some examples, when the relay UE 200 sends a notification message to the remote UE 250 when a reconfiguration failure triggers a connection reestablishment, a known indication type (e.g., relayUE-Uu-RRC-Failure or relayUE-HO) is used. Reusing the existing indication type in the notification message does not require any implementation changes in the remote UE 250. The remote UE 250 will be triggered to initiate its own connection reestablishment upon receiving the notification message.

[0120] In some examples, one or more new indication types may be introduced for sending a notification message from the relay UE 200 to the remote UE 250 in response to a reconfiguration failure at the relay UE 200. For example, new indication types may be introduced, such as relayUE-Uu-Reestablishment or relayUE-UU-RRCReconfiguration-Failure. For example, relayUE-Uu-Reestablishment or relayUE-UU-RRCReconfiguration-Failure may be used in Option 2 or Option 1 in the case where the relay UE fails or succeeds in reestablishing but to a different cell, or there is no configuration associated with the remote UE 250, or a different configuration associated with the remote UE 250. In another implementation example, different indication types may be introduced for different reestablishment process results, such as relayUE-Uu-ReetablishmentSuccess and relayUE-Uu-ReetablishmentFailure. In the example using the relayUE-Uu-ReetablishmentSuccess indication, the remote UE 250 may be triggered to initiate its own connection re-establishment via the relay UE 200, for example if the PC5 connection with the relay UE is maintained.

[0121] In some examples, the gNB 202 may configure the behavior of the relay UE 200. For example, the gNB 202 may configure the behavior of the relay UE 200 to "notify when reconfiguration fails" (e.g., whether to send a notification message immediately as suggested in Option 2, or to wait for the reestablishment result to send a notification message as suggested in Option 1). In some examples, the behavior of the relay UE 200 is based on configured conditions. These conditions may depend on the purpose of the reconfiguration (e.g., addition / change of service / QoS flow, addition and release of SCG (secondary cell group), change of PC5 configuration, etc.) and / or the Uu or PC5 radio channel conditions of the relay UE.

[0122] In one example, if "Notify on Reconfiguration Failure" is enabled (i.e., enabling the sending of a sidelink notification message from the relay UE 200 to the remote UE 250), the relay UE 200 may determine which option (i.e., option 1 or option 2) is applied by the UE implementation. In some examples, the relay UE's determination may be based on the reconfiguration purpose, Uu and / or PC5 radio channel conditions and mobility status, or its own hardware (HW) status (battery, processing load, etc.).

[0123] In one example, when triggering reestablishment, the relay UE 200 may consider service continuity for the remote UE. For example, if the remote UE 250 is performing a path switch, the relay UE 200 may delay the reestablishment to a maximum time.

[0124] Figure 7 Shows the control Figure 1 The access network shown in Figure 1 700 for controlling the functions of a 5G-RAN or NG-RAN) shown in FIG. The control device 700 may include at least one random access memory (RAM) 711a, at least one read-only memory (ROM) 711b, at least one processor 712, 713, and a network interface 714. At least one processor 712, 713 may be coupled to the RAM 711a and the ROM 711b. At least one processor 712, 713 may be configured to execute appropriate software code 715. The execution of the software code 715 may, for example, cause the device to perform operations for controlling access network functions. The software code 715 may be stored in the ROM 711b. The control device 700 may be interconnected with another control device 700 for controlling another function of the 5G-RAN or NG-RAN. In some embodiments, each function of the 5G-RAN or NG-RAN is deployed or hosted on the control device 700. In an alternative embodiment, two or more functions of the 5G-RAN or NG-RAN may share a control device. For example, the gNB 202 may be in the form of a control device 700.

[0125] Figure 8 An example of a communication device 800 is shown, such as Figure 1 UE or terminal shown. The communication device 800 can be provided by any device capable of sending and receiving radio signals. Non-limiting examples of the communication device 800 include user equipment, a mobile station (MS) or a mobile device (such as a mobile phone or a so-called "smart phone"), a computer provided with a wireless interface card or other wireless interface facilities (such as a USB dongle), a personal digital assistant (PDA) or a tablet computer provided with wireless communication capabilities, a machine type communication (MTC) device, an Internet of Things (IoT) type communication device, or any combination of these and the like. The communication device 800 may include a transceiver for sending and / or receiving, for example, radio signals carrying communications, such as radio signals. The communication may be one or more of voice, electronic mail (email), text message, multimedia data, machine data, etc.

[0126] The communication device 800 may receive wireless signals (eg, radio signals) over the air or over the radio interface 807 via appropriate means for receiving, and may send wireless signals via appropriate means for sending radio signals. Figure 8 8, a transceiver is schematically designated by block 806. The transceiver 806 may include, for example, a radio portion and an associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device and may include one or more antenna elements. The antenna arrangement may be a multiple-input multiple-output (MIMO) antenna.

[0127] The communication device 800 may be provided with at least one processor 801, at least one memory ROM 802a, at least one RAM 802b and other possible components 803 for software and hardware assisted execution of the tasks it is designed to perform, including access to a network (e.g. Figure 1 The at least one processor 801 is coupled to the RAM 802b and the ROM 802a. The at least one processor 801 may be configured to execute appropriate software code 808. The software code 808 may, for example, allow execution of one or more operations of the communication device 800. The software code 808 may be stored in the ROM 802a. For example, the relay UE 200 or the remote UE 250 may take the form of the UE 800.

[0128] The processor, ROM and RAM, transceiver and other circuits of the communication device (e.g., modem) may be provided on a circuit board, chipset or system on chip. The circuit board, chipset or system on chip is represented by reference 804. The communication device 800 may optionally have a user interface, such as a keyboard 805, a touch-sensitive screen or keyboard, a combination thereof, etc. Optionally, one or more of a display, a speaker and a microphone may be provided, depending on the type of communication device.

[0129] For example, the relay UE 200 or the remote UE 250 may be in the form of the UE 800 .

[0130] Fig. 9 2 is a flow chart of a method viewed from the perspective of a device. For example, the device may be a relay UE 200.

[0131] As shown at S901 , the method includes, when the apparatus acts as a relay between a base station and a remote user equipment, receiving a reconfiguration request from a base station.

[0132] As shown at S902 , the method includes determining a reconfiguration failure at a device associated with a reconfiguration request.

[0133] As shown at S903 , the method includes: in response to determining that the reconfiguration of the apparatus has failed, generating a notification for a remote user equipment.

[0134] As shown in S904, the method includes: sending a notification to a remote user equipment.

[0135] Fig.10 2 is a flow chart of a method viewed from the perspective of an apparatus. For example, the device may be a remote UE 250.

[0136] As shown in S1001 , the method includes: receiving a notification from a relay user equipment, the relay user equipment serving as a relay between a device and a base station, wherein the notification is associated with a reconfiguration failure of the relay user equipment.

[0137] As shown at S1002, the method includes: in response to receiving the notification, performing a connection reestablishment process between the device and the base station or another base station.

[0138] Fig.11 A schematic diagram showing non-volatile storage media 1100a (e.g., a computer compact disk (CD) or a digital versatile disk (DVD)) and 1100b (e.g., a universal serial bus (USB) memory stick) storing instructions and / or parameters 1102 that, when executed by a processor, allow the processor to perform Fig. 9 or Fig.10 One or more steps of the method shown.

[0139] It should be understood that the above references to various network functions (e.g., AMF, SMF, TNF, etc.) may include devices that perform at least some functions related to those network functions. Further, the device including the network function may include a virtual network function instance of the network function.

[0140] It should be understood that the apparatus may include or be coupled to other units or modules used or for transmission and / or reception, such as a radio component or radio head, etc. Although the apparatus is described as one entity, the different modules and memories may be implemented in one or more physical or logical entities.

[0141] Note that while some embodiments have been described in relation to 5G networks, similar principles may be applied in relation to other networks and communication systems. Thus, while certain embodiments have been described above in an example manner with reference to certain example architectures for wireless networks, technologies, and standards, the embodiments may be applied to any other suitable form of communication system in addition to those shown and described herein.

[0142] It is also noted herein that while the above describes exemplifying embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

[0143] As used herein, “at least one of: ” and “at least one of ” and similar expressions, where a list of two or more elements is connected by “and” or “or”, mean at least any one element, or at least any two or more elements, or at least all elements.

[0144] In general, various embodiments may be implemented in hardware or dedicated circuits, software, logic, or any combination thereof. Some aspects of the disclosure may be implemented in hardware, while other aspects may be implemented in firmware or software, which may be executed by a controller, microprocessor, or other computing device, although the disclosure is not limited thereto. Although various aspects of the disclosure may be illustrated and described with block diagrams, flow charts, or using some other graphical representation, it is well known that, as non-limiting examples, the blocks, devices, systems, techniques, or methods described herein may be implemented in hardware, software, firmware, dedicated circuits or logic, general purpose hardware or controllers or other computing devices, or some combination thereof.

[0145] As used herein, the term "circuitry" may refer to one or more or all of the following:

[0146] (a) Pure hardware circuit implementation (such as implementation only in analog and / or digital circuits)

[0147] (b) a combination of hardware circuitry and software such as (where applicable):

[0148] (i) a combination of analog and / or digital hardware circuitry and software / firmware, and

[0149] (ii) any portion of hardware processor(s) with software (including digital signal processor(s)), software and memory(s) that work together to enable a device (such as a mobile phone or server) to perform various functions and (c) hardware circuit(s) and / or processor(s), such as microprocessor(s) or portion(s) of microprocessor(s), which requires software (e.g. firmware) to operate, but which may be absent when not required for operation.

[0150] This definition of circuitry applies to all uses of the term herein, including in any claims. As a further example, as used herein, the term circuitry also includes an implementation of only a hardware circuit or a processor (or multiple processors) or a portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. For example, if applicable to a particular claim element, the term circuitry also covers a baseband integrated circuit or processor integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or network device.

[0151] Embodiments of the present disclosure may be implemented by computer software executable by a data processor of a mobile device (such as in a processor entity), or by hardware, or by a combination of software and hardware. Computer software or programs, also referred to as program products (including software routines, applets and / or macros), may be stored in a data storage medium readable by any device, and they include program instructions for performing specific tasks. A computer program product may include one or more computer executable components that are configured to perform embodiments when the program is running. One or more computer executable components may be at least one software code or a portion thereof.

[0152] In addition, it should be noted at this point that any block of the logic flow as shown in the figure can represent a program step, or a logic circuit, block and function connected to each other, or a combination of a program step and a logic circuit, block and function. The software can be stored on a physical medium (such as a memory chip or a memory block implemented in a processor), a magnetic medium (such as a hard disk or a floppy disk), and an optical medium (such as, for example, a DVD and its data variants, a CD). A physical medium is a non-transient medium.

[0153] The term "non-transitory" as used herein is a restriction to the medium itself (ie, tangible, not a signal), not to the persistence of data storage (eg, RAM vs. ROM).

[0154] The memory may be of any type suitable for the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based storage devices, magnetic storage devices and systems, optical storage devices and systems, fixed memory, and removable memory. As non-limiting examples, the data processor may be of any type suitable for the local technical environment and may include, as non-limiting examples, one or more of the following: a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), an FPGA, a gate-level circuit, and a processor based on a multi-core processor architecture.

[0155] Various example embodiments of the present disclosure may be practiced in various components such as integrated circuit modules. The design of integrated circuits is essentially a highly automated process. Complex and powerful software tools can be used to convert logic-level designs into semiconductor circuit designs that are ready to be etched and formed on semiconductor substrates.

[0156] The independent claims define the scope of protection sought for various example embodiments of the present disclosure. Example embodiments and features thereof (if any) described in the present disclosure that do not fall within the scope of the independent claims should be interpreted as examples that aid in understanding the various example embodiments of the present disclosure.

[0157] The foregoing description provides a complete and informative description of various example embodiments of the present disclosure by way of non-limiting and illustrative examples. However, when read in conjunction with the accompanying drawings and claims, various modifications and adjustments will become apparent to those skilled in the relevant art in view of the foregoing description. However, all of these and similar modifications taught will still fall within the various example embodiments of the present disclosure set forth in the claims. As a non-limiting and illustrative example, there is another example embodiment comprising a combination of one or more example embodiments with any of the foregoing any example embodiments.

Claims

1. A device for communication, comprising: means for receiving a reconfiguration request from the base station when the apparatus acts as a relay between the base station and a remote user equipment; means for determining a reconfiguration failure at the device associated with the reconfiguration request; means for generating a notification for said remote user equipment in response to said determining that reconfiguration at said apparatus has failed; as well as Means for sending the notification to the remote user equipment.

2. The device according to claim 1, comprising: Means for performing a connection reestablishment procedure with the base station or another base station.

3. An apparatus according to claim 2, wherein the component for sending the notification to the remote user equipment is configured to: send the notification to the remote user equipment before performing the connection reestablishment procedure or before the result of the connection reestablishment procedure with the base station or another base station is known.

4. The apparatus according to any one of claims 1 to 3, wherein the means for sending the notification to the remote user equipment is configured to send the notification immediately or substantially immediately after the determination that the reconfiguration has failed.

5. An apparatus according to any one of claims 1 to 4, wherein the means for generating the notification is configured to generate a notification arranged so that the remote user equipment does not use the apparatus to perform a connection reestablishment procedure with the base station or another base station.

6. The apparatus of claim 2, wherein the means for sending the notification to the remote user equipment is configured to send the notification to the remote user equipment after a result of the connection reestablishment procedure with the base station or another base station is known.

7. The apparatus of claim 6, wherein the means for generating the notification is configured to generate the notification in a manner that is dependent on the outcome of the connection reestablishment procedure.

8. The apparatus according to claim 7, wherein when the result of the connection reestablishment procedure is a failure of the connection reestablishment procedure, the component for generating a notification is configured to generate a notification, the notification being arranged so that the remote user equipment does not use the apparatus to perform a connection reestablishment procedure for the remote user equipment and the base station or another base station.

9. An apparatus according to claim 7, wherein when the result of the connection reestablishment process is the success of the connection reestablishment process, the component for generating a notification is configured to generate a notification, and the notification also depends on one or more of the following items: whether there has been a cell change of the apparatus as a result of the connection reestablishment process; whether there has been a configuration change of the remote user equipment as a result of the connection reestablishment process.

10. An apparatus for communication, comprising: means for receiving a notification from a relay user equipment, the relay user equipment acting as a relay between the apparatus and a base station, wherein the notification is associated with a reconfiguration failure of the relay user equipment; as well as Means for performing a connection reestablishment procedure between the apparatus and the base station or another base station in response to receiving the notification.

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