Method and apparatus for an extended mechanism for the RRC re - establishment procedure

Abstract

Embodiments of the present disclosure relate to a method and apparatus for an extended mechanism for a radio resource control (RRC) reestablishment procedure. According to one embodiment of the present application, a user equipment (UE) includes a transceiver and a processor coupled to the transceiver, and the processor is configured to start a radio resource control (RRC) reestablishment procedure, transmit an RRC reestablishment request message to a network node via a relay node by the transceiver, start a timer for the RRC reestablishment request in response to the transmission of the RRC reestablishment request message, and stop the timer for the RRC reestablishment request in response to a pre-specified condition associated with the reception of a notification message being satisfied.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to wireless communication technologies, and more particularly, to methods and apparatuses for an extended mechanism for a radio resource control (RRC) reestablishment procedure.

Background Art

[0002] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcast, etc. A wireless communication system may employ a multiple access technology capable of supporting communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of wireless communication systems may include fourth generation (4G) systems such as Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth generation (5G) systems sometimes referred to as New Radio (NR) systems.

[0003] In the above wireless communication system, a user equipment (UE) may communicate with another UE via a data path supported by a carrier's network, e.g., a cellular or Wi-Fi network infrastructure. The data path supported by the carrier's network may include a base station (BS) and a plurality of gateways.

[0004] Some wireless communication systems may support sidelink communication, in which devices (e.g., UEs) that are relatively close to each other can communicate directly with each other via a sidelink rather than being linked through a BS. A relay function based on the sidelink can be supported in a communication network. For example, a UE that supports sidelink communication can function as a relay node to extend the coverage of a BS. UEs outside or within the coverage can communicate with the BS via a relay node (e.g., a relay UE). In the context of the present disclosure, a UE that functions as a relay between another UE and a BS may be referred to as a UE-to-network (U2N) relay.

[0005] A UE can be in an RRC connected state, an RRC idle state, or an RRC inactive state. The RRC connected state may also be referred to as the "connected state" or the "RRC_CONNECTED state". The RRC idle state may also be referred to as the "idle state" or the "RRC_IDLE state". The RRC inactive state may also be referred to as the "inactive state" or the "RRC_INACTIVE state".

[0006] In a communication system that supports U2N relays, it is necessary to execute communication efficiently.

SUMMARY OF THE INVENTION

MEANS FOR SOLVING THE PROBLEM

[0007] Some embodiments of the present application provide a user equipment (UE). The UE includes a transceiver and a processor coupled to the transceiver, and the processor is configured to initiate a first Radio Resource Control (RRC) re-establishment procedure, transmit, by the transceiver, a first RRC re-establishment request message to a network node via a first relay node, start a first timer for the RRC re-establishment request in response to the transmission of the first RRC re-establishment request message, and stop the first timer for the RRC re-establishment request in response to a pre-specified condition associated with the reception of a notification message being satisfied.

[0008] In some embodiments, the notification message indicates at least one of a handover of the first relay node, a Radio Link Failure (RLF) between the first relay node and the network node, a cell reselection of the first relay node, or an RRC connection failure of the first relay node, and the RRC connection failure of the first relay node includes an RRC connection rejection, an expiration of a timer (e.g., T300) for transmitting an RRCSetupRequest, and / or an RRC resume failure.

[0009] In some embodiments, the processor of the UE is configured to release configuration information related to a PC5 relay Radio Link Control (RLC) channel in response to at least one of the initiation of the first RRC re-establishment procedure, or the initiation of the first RRC re-establishment procedure and the UE not being configured with a conditional reconfiguration configuration associated with a candidate target cell, or the initiation of the first RRC re-establishment procedure and the selected cell being configured with a conditional handover (CHO) for the first time after a failure and the UE being not configured with an indication that the UE should perform a conditional reconfiguration configuration.

[0010] In some embodiments, the UE's processor is configured to perform at least one of a first cell selection operation, a first relay selection operation, or a first relay reselection operation in response to the start of a first RRC reestablishment procedure.

[0011] In some embodiments, the UE's processor is configured to receive a notification message from a first relay node via a transceiver.

[0012] In some embodiments, the UE's processor is configured to enter the RRC idle state in response to a pre-specified condition being met or in response to the stop of a first timer for an RRC reestablishment request.

[0013] In some embodiments, the UE's processor is configured to start a second RRC reestablishment procedure in response to a pre-specified condition being met or in response to the stop of a first timer for an RRC reestablishment request.

[0014] In some embodiments, the pre-specified condition includes a cell change upon receipt of a notification message.

[0015] In some embodiments, the pre-specified condition includes at least one of receiving a notification message from a first relay node, the UE deeming the selected cell inappropriate upon receipt of the notification message, the UE deeming a cell selection operation to occur upon receipt of the notification message, and the UE deeming the first timer for an RRC reestablishment request to expire upon receipt of the notification message.

[0016] In some embodiments, after starting the second RRC reestablishment procedure, the UE's processor is configured to perform at least one of a second cell selection operation, a second relay selection operation, or a second relay reselection operation.

[0017] In some embodiments, during at least one of the second cell selection operation, the second relay selection operation, or the second relay reselection operation, the first relay node is not allowed to be selected in response to another suitable relay node being available or a suitable cell being available, and the first relay node is allowed to be selected in response to a notification message indicating a duration and the duration having elapsed after receipt of the notification message, or a discovery message received from the first relay node including a cell ID different from the first cell identifier (ID) of the first relay node.

[0018] In some embodiments, a processor of the UE is configured to transmit, by a transceiver, a second RRC reestablishment request message to a network node and, in response to transmission of the second RRC reestablishment request message, start a second timer for the RRC reestablishment request.

[0019] In some embodiments, a processor of the UE is configured to receive, by a transceiver, an RRC reestablishment message in response to a first RRC reestablishment request message from a network node.

[0020] In some embodiments, the RRC reestablishment message is received before transmitting the second RRC reestablishment request message or after transmitting the second RRC reestablishment request message for a short duration.

[0021] In some embodiments, in response to receipt of the RRC reestablishment message, a processor of the UE is configured to discard the RRC reestablishment message or apply the RRC reestablishment message and stop the second timer for the RRC reestablishment request.

[0022] Some embodiments of the present application provide a method executable by a UE. The method includes starting a first Radio Resource Control (RRC) re-establishment procedure, transmitting a first RRC re-establishment request message to a network node via a first relay node, starting a first timer for the RRC re-establishment request in response to the transmission of the first RRC re-establishment request message, and stopping the first timer for the RRC re-establishment request in response to a pre-specified condition associated with the reception of a notification message being satisfied.

[0023] In some embodiments, the notification message indicates at least one of a handover of the first relay node, a Radio Link Failure (RLF) between the first relay node and the network node, a cell reselection of the first relay node, or an RRC connection failure of the first relay node, and the RRC connection failure of the first relay node includes an RRC connection rejection, an expiration of a timer (e.g., T300) for transmitting an RRCSetupRequest, and / or an RRC resume failure.

[0024] In some embodiments, the method further includes releasing configuration information related to a PC5 relay Radio Link Control (RLC) channel in response to at least one of starting the first RRC re-establishment procedure, or starting the first RRC re-establishment procedure and the UE not being configured with a conditional reconfiguration configuration associated with a candidate target cell, or starting the first RRC re-establishment procedure and the UE not being configured with an indication for performing a conditional reconfiguration configuration when the selected cell is configured with a conditional handover (CHO) for the first time after a failure.

[0025] In some embodiments, the method further includes performing at least one of a first cell selection operation, a first relay selection operation, or a first relay reselection operation in response to starting the first RRC re-establishment procedure.

[0026] In some embodiments, the method further includes receiving a notification message from a first relay node.

[0027] In some embodiments, the method further includes entering the RRC idle state in response to a pre-specified condition being met or in response to the stopping of a first timer for an RRC re-establishment request.

[0028] In some embodiments, the method further includes starting a second RRC re-establishment procedure in response to a pre-specified condition being met or in response to the stopping of a first timer for an RRC re-establishment request.

[0029] In some embodiments, the pre-specified condition includes a cell change upon receipt of the notification message.

[0030] In some embodiments, the pre-specified condition includes at least one of: receiving a notification message from the first relay node; the UE deeming the selected cell inappropriate upon receipt of the notification message; the UE deeming a cell selection operation to occur upon receipt of the notification message; and the UE deeming the first timer for the RRC re-establishment request to expire upon receipt of the notification message.

[0031] In some embodiments, the method further includes performing at least one of a second cell selection operation, a second relay selection operation, or a second relay reselection operation after starting the second RRC re-establishment procedure.

[0032] In some embodiments, during at least one of the second cell selection operation, the second relay selection operation, or the second relay reselection operation, the first relay node is not permitted to be selected in response to another suitable relay node being available or a suitable cell being available, and the first relay node is permitted to be selected in response to a notification message indicating a duration and the duration having elapsed since receipt of the notification message or a discovery message received from the first relay node including a cell ID different from the first cell identifier (ID) of the first relay node.

[0033] In some embodiments, the method further includes transmitting a second RRC re - establishment request message to a network node and starting a second timer for the RRC re - establishment request in response to the transmission of the second RRC re - establishment request message.

[0034] In some embodiments, the method further includes receiving, from a network node, an RRC re - establishment message in response to the first RRC re - establishment request message.

[0035] In some embodiments, the RRC re - establishment message is received before transmitting the second RRC re - establishment request message or after transmitting the second RRC re - establishment request message for a short duration.

[0036] In some embodiments, in response to receiving the RRC re - establishment message, the method further includes discarding the RRC re - establishment message or applying the RRC re - establishment message and stopping the second timer for the RRC re - establishment request.

[0037] Some embodiments of the present application also provide an apparatus for wireless communication. The apparatus includes a non-transitory computer-readable medium storing computer-executable instructions, a receiving circuit, a transmitting circuit, and a processor coupled to the non-transitory computer-readable medium, the receiving circuit, and the transmitting circuit, and the computer-executable instructions cause the processor to perform any of the above-described methods executed by a remote UE or a relay UE.

[0038] Details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.

[0039] To explain how the advantages and features of the present disclosure can be obtained, the description of the present disclosure is made by referring to the specific embodiments shown in the accompanying drawings. These drawings show only exemplary embodiments of the present disclosure and should not be regarded as limiting the scope thereof.

Brief Description of the Drawings

[0040]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

[0041] The detailed description of the accompanying drawings is intended as a description of the preferred embodiments of the present disclosure and does not represent the only form in which the present disclosure may be implemented. It should be understood that the same or equivalent functions may be achieved by different embodiments that are within the spirit and scope of the present disclosure.

[0042] Next, some embodiments of the present disclosure will be referred to in detail, examples of which are shown in the accompanying drawings. For ease of understanding, the embodiments are provided under specific network architectures and new service scenarios such as the 3rd Generation Partnership Project (3GPP) 5G (NR), 3GPP Long Term Evolution (LTE) Release 8, etc. (where "3GPP" is a registered trademark). With the development of network architectures and new service scenarios, all embodiments in the present disclosure are also applicable to similar technical problems. Furthermore, the terms described in the present disclosure may change, and it is intended that this should not affect the principles of the present disclosure.

[0043] FIG. 1 shows a schematic diagram of a wireless communication system 100 according to some embodiments of the present disclosure.

[0044] As shown in FIG. 1, the wireless communication system 100 may support sidelink communication. Sidelink communication supports direct communication between UEs. In the context of the present disclosure, sidelink communication may be classified according to the wireless communication technology employed. For example, sidelink communication may include NR sidelink communication and V2X sidelink communication.

[0045] NR side - link communication (e.g., as specified in 3GPP specification TS38.311) refers to an access stratum (AS) function that enables at least vehicle - to - everything (V2X) communication between neighboring UEs, as defined in 3GPP specification TS23.287, which uses NR technology but does not traverse any network nodes. V2X side - link communication (e.g., as specified in 3GPP specification TS36.311) refers to an AS function that enables V2X communication between neighboring UEs, as defined in 3GPP specification TS23.285, which uses evolved universal mobile telecommunications system (UMTS) terrestrial radio access (UTRA) (E - UTRA) technology but does not traverse any network nodes. However, when not specified, "side - link communication" may refer to NR side - link communication, V2X side - link communication, or any side - link communication that employs other wireless communication technologies.

[0046] Referring to FIG. 1, wireless communication system 100 may include several base stations (e.g., BS102 and BS103) and several UEs (e.g., UE101A, UE101B, and UE101C). Although a specific number of UEs and BSs are shown in FIG. 1, it is contemplated that any number of UEs and BSs may be included in wireless communication system 100.

[0047] The UE and the BS may support communication based on, for example, 3G, Long Term Evolution (LTE), LTE-Advanced (LTE-A), New Radio (NR), or other suitable protocols. In some embodiments of the present disclosure, the BS (e.g., BS102 or BS103) may be referred to as an access point, access terminal, base, base unit, macrocell, Node B, evolved Node B (eNB), gNB, ng-eNB, home Node B, relay Node, or device, or may be described using other terms used in the art. The UE (e.g., UE101A, UE101B, or UE101C) may include, for example, but not limited to, computing devices, wearable devices, mobile devices, IoT devices, vehicles, etc. As technology develops and progresses, the terms described in the present disclosure may change, but those skilled in the art should understand that they should not affect or limit the principles and spirit of the present disclosure.

[0048] In the example of FIG. 1, BS102 and BS103 may be included in the Next Generation Radio Access Network (NG-RAN). In some embodiments of the present disclosure, BS102 may be a gNB, and BS103 may be an ng-eNB.

[0049] UE101A and UE101B can be within coverage (e.g., inside the NG-RAN). For example, as shown in FIG. 1, UE101A can be within the coverage of BS102, and UE101B can be within the coverage of BS103. UE101C can be outside the coverage (e.g., outside the coverage of the NG-RAN). For example, as shown in FIG. 1, UE101C can be outside the coverage of any BS, e.g., both BS102 and BS103. UE101A and UE101B can be connected to BS102 and BS103 respectively via a network interface, e.g., the Uu interface specified in 3GPP standard documents. The control plane protocol stack in the Uu interface may include a Radio Resource Control (RRC) layer, sometimes called Uu RRC. The link established between a UE (e.g., UE101A) and a BS (e.g., BS102) may be called a Uu link. BS102 and BS103 can be connected to each other via a network interface, e.g., the Xn interface specified in 3GPP standard documents. UE101A, UE101B, and UE101C can be connected to each other via, for example, the PC5 interface specified in 3GPP standard documents. The control plane protocol stack in the PC5 interface may include a Radio Resource Control (RRC) layer, sometimes called PC5 RRC. The link established between two UEs (e.g., UE101A and UE101B) may be called a PC5 link.

[0050] Support for V2X services via the PC5 interface can be provided, for example, by NR sidelink communication and / or V2X sidelink communication. NR sidelink communication can support one of the following three types of transmission modes for a pair of source layer 2 identification information and destination layer 2 identification information, namely, unicast transmission, groupcast transmission, and broadcast transmission. Sidelink communication transmission and reception on the PC5 interface are supported when the UE is either within or outside the coverage. For example, UE101A within the coverage of BS102 can perform sidelink transmission and reception (e.g., sidelink unicast transmission, sidelink groupcast transmission, or sidelink broadcast transmission) on the PC5 interface. UE101C outside the coverage of both BS102 and BS103 can also perform sidelink transmission and reception on the PC5 interface.

[0051] A UE that supports sidelink communication and / or V2X communication may be referred to as a V2X UE. The V2X UE can be a smartphone, a vehicle, a roadmap device, a computer, a laptop, an IoT (Internet of Things) device, or some other type of device according to some other embodiments of the present disclosure.

[0052] As described above, the relay function based on sidelink can be supported in a communication network. In some embodiments of the present disclosure, UE-to-network relay is supported. For example, a coverage UE communicating with a remote UE (e.g., an out-of-coverage UE or an in-coverage UE) can function as a relay UE between the serving BS of the coverage UE and the remote UE. Accordingly, the remote UE can communicate with the BS via this relay UE. Data between the remote UE and the BS can be transferred by the relay UE. In this scenario, the relay UE may be referred to as the serving relay of the remote UE, and the serving BS or serving cell of the relay UE may be referred to as the serving BS or serving cell of the remote UE.

[0053] FIG. 2 shows a schematic diagram of a relay-based wireless communication system 200 according to some embodiments of the present disclosure. The details described in all of the above embodiments of the present disclosure are applicable to the embodiments shown in FIG. 2.

[0054] As shown in FIG. 2, the wireless communication system 200 may include a BS (e.g., BS 202) and several UEs (e.g., UE 201A and UE 201B). Although a specific number of UEs and BSs are shown in FIG. 2, it is contemplated that any number of UEs and BSs may be included in the wireless communication system 200. In some examples, UE 201B may function as UE 101A or UE 101B shown in FIG. 1, and UE 201A may function as UE 101C shown in FIG. 1.

[0055] UE 201B may be within the coverage of BS 202. For example, UE 201B and BS 202 may establish an RRC connection therebetween. UE 201A may be outside the coverage of BS 202. The wireless communication system 200 may support sidelink communication. For example, UE 201B may be in sidelink communication with UE 201A. A PC5 RRC connection may be established between UE 201A and UE 201B.

[0056] In some embodiments of the present disclosure, UE201A may initiate a procedure to establish a connection with BS202 via UE201B (i.e., UE-to-network relay). For example, UE201A may send an RRC setup request to BS202 via UE201B. BS202 may send an RRC setup message including a response to UE201A via UE201B. After such a procedure, UE201A may access BS202 (e.g., a cell of BS202) via UE201B. This cell may be referred to as the serving cell of UE201A. UE201A and BS202 may establish an RRC connection therebetween. UE201A may have an RRC state such as the RRC_IDLE state, the RRC_INACTIVE state, and the RRC_CONNECTED state. UE201A may also be referred to as a remote UE, and UE201B may also be referred to as the relay UE or serving relay of UE201A.

[0057] Although a single relay node (e.g., UE201B) between UE201A and BS202 is shown in FIG. 2, those skilled in the art should understand that any number of relay nodes may be included. Although it is shown in FIG. 2 that UE201A is outside the coverage of BS202, it is contemplated that in some other embodiments of the present disclosure, UE201A may be within the coverage of BS202. In these embodiments, UE201A may connect directly to BS202 and / or connect to BS202 via UE201B.

[0058] A UE (e.g., UE201A or UE201B in FIG. 2) can be in one of the following states at a given time: the RRC_IDLE state, the RRC_CONNECTED state, and the RRC_INACTIVE state. In the RRC_INACTIVE state (hereinafter, the "inactive state"), the UE does not have an RRC connection with a radio access network (RAN), e.g., BS202. However, the RAN maintains a connection with the core network for the UE. Thus, the RRC_INACTIVE state can achieve power saving with acceptable access latency. Specific characteristics of the RRC_IDLE state, the RRC_CONNECTED state, and the RRC_INACTIVE state are defined in 3GPP specifications.

[0059] FIG. 3 shows a flowchart of an exemplary procedure 300 for re - establishing an RRC connection according to some embodiments of the present disclosure. The details described in all of the above - described embodiments of the present disclosure are applicable to the embodiment shown in FIG. 3.

[0060] The purpose of the exemplary procedure 300 is to re - establish an RRC connection. In response to the start of the procedure, the UE301 can start a timer (e.g., T311 specified in 3GPP specifications) for starting RRC re - establishment and perform cell or relay selection. In response to the selection of a suitable relay node (e.g., an L2 U2N relay UE), the UE301 (e.g., a remote UE) can stop the timer for starting RRC re - establishment. The UE301 can transmit an RRC re - establishment request message to the network 302 (e.g., a BS or a cell) in operation 311. In response to the transmission of the RRC re - establishment request message, the UE301 can start a timer (e.g., T301 specified in 3GPP specifications) for the RRC re - establishment request.

[0061] In response to the RRC re - establishment request message, the network 302 may transmit an RRC re - establishment message to the UE 301 in operation 312. In response to the reception of the RRC re - establishment message, the UE 301 may stop the timer for the RRC re - establishment request. The UE 301 may apply the configuration according to the RRC re - establishment message and may transmit an RRC re - establishment complete message to the network 302 in operation 313.

[0062] Embodiments of the present application aim to solve problems during the RRC re - establishment procedure in a network that supports the case of U2N relay. For example, some embodiments of the present application consider an extended mechanism for the RRC re - establishment procedure in the case of U2N relay. In some embodiments of the present application, after the remote UE stops the timer T301 for receiving the notification message, the remote UE is allowed to re - transmit the RRC re - establishment request message. Some embodiments of the present application consider the principles that the cell selection operation and / or the relay (re) - selection operation may follow. Some embodiments of the present application aim to solve the problem of potential inconsistency between the remote UE and the serving cell. Some embodiments of the present application introduce a stop condition for the timer T301 in the case of a specific relay.

[0063] Further details are shown in the following text in combination with the accompanying drawings. Those skilled in the art should be well aware that expressions such as "the first", "the second", and "the third" are used only for clear explanation and should not be regarded as any substantial limitation, such as a limitation of order.

[0064] Figure 4 shows an exemplary flowchart 400 for initiating an RRC re-establishment procedure according to some embodiments of the present disclosure. The exemplary flowchart 400 may be executed by a UE (e.g., a remote UE). A specific example of the exemplary flowchart 400 will be described in the embodiments of FIGS. 5 and 6 as follows. Although described with respect to a UE, it should be understood that other devices may be configured to execute in a manner similar to the method of FIG. 4.

[0065] Referring to FIG. 4, in operation 401, a UE (e.g., UE201A, UE301, UE501, or UE601 as shown in any of FIGS. 2, 3, 5, and 6) may initiate an RRC re-establishment procedure.

[0066] In operation 402, the UE may send an RRC re-establishment request message to a network node (e.g., BS202, network 302, BS503, or BS603 as shown in any of FIGS. 2, 3, 5, and 6) via a relay node (e.g., relay UE201B, relay UE502B, or relay UE602B as shown in any of FIGS. 2, 5, and 6). The RRC re-establishment request message may be denoted as the "first RRC re-establishment request message" for simplicity. The relay node may be denoted as the "first relay UE" for simplicity. In some embodiments, before initiating the RRC re-establishment procedure, the UE may access the serving cell of the network node via a direct path or via another relay node (e.g., relay UE502A or relay UE602A as shown in FIG. 5 or FIG. 6).

[0067] In operation 403, in response to sending the RRC re-establishment request message, the UE may start a timer (e.g., T301 specified in the 3GPP specification) for the RRC re-establishment request.

[0068] In operation 404, the UE may stop a timer for an RRC re - establishment request in response to a pre - specified condition associated with the reception of a notification message being satisfied.

[0069] In some embodiments, the UE may receive a notification message from a relay UE. In some embodiments, the notification message indicates at least one of: handover of a first relay node, radio link failure (RLF) between a first relay node and a network node, cell reselection of a first relay node, or RRC connection failure of a first relay node. For example, the RRC connection failure of the first relay node may include RRC connection rejection, expiration of a timer (e.g., T300) for transmitting RRCSetupRequest, and / or RRC resume failure.

[0070] In some embodiments, the UE may release configuration information related to the PC5 RLC channel in response to the start of an RRC re - establishment procedure. For example, the PC5 relay RLC channel is an RLC channel between an L2 U2N remote UE and an L2 U2N relay UE used to transport packets on the PC5 link for L2 U2N relay. In one embodiment, the configuration information related to the PC5 relay RLC channel may be released in response to at least one of the following. (1) The start of the RRC re - establishment procedure and the UE not being configured with a conditional re - configuration configuration (e.g., conditional Reconfiguration information element (IE)) associated with a candidate target cell. (2) The start of the RRC re - establishment procedure and the UE not being configured with an indication (e.g., attemptCondReconfig IE) indicating that the UE should perform a conditional re - configuration configuration associated with a candidate target cell when the selected cell is configured with CHO for the first time after a failure.

[0071] In some embodiments, the UE may perform at least one of a cell selection operation, a relay selection operation, or a relay reselection operation in response to the start of an RRC reestablishment procedure. For example, a first relay node (e.g., relay UE 502B or relay UE 602B as shown in FIG. 5 or FIG. 6) may be selected by the UE by performing at least one of a cell selection operation, a relay selection operation, or a relay reselection operation.

[0072] In some embodiments, the UE may enter the RRC idle state in response to a pre-specified condition being met or in response to the stop of a timer for an RRC reestablishment request. A specific example will be described in the embodiment of FIG. 5 as follows.

[0073] In some embodiments, the UE may initiate another RRC reestablishment procedure (shown as the "second RRC reestablishment procedure" for simplicity) in response to a pre-specified condition being met or in response to the stop of a timer for an RRC reestablishment request. A specific example will be described in the embodiment of FIG. 6 as follows.

[0074] In some embodiments, the pre-specified condition includes a cell change upon reception of a notification message.

[0075] In some embodiments, the pre-specified condition includes at least one of reception of a notification message from a first relay node, the UE deeming the selected cell inappropriate upon reception of the notification message, the UE deeming a cell selection operation to occur upon reception of the notification message, and the UE deeming the timer for the RRC reestablishment request to expire upon reception of the notification message.

[0076] In some embodiments, after starting the second RRC re - establishment procedure, the UE may perform at least one of another cell selection operation, another relay selection operation, or another relay reselection operation. In one embodiment, during at least one of these operations, the first relay node is not allowed to be selected "in response to another suitable relay node being available" or "in response to a suitable cell being available". In one embodiment, during at least one of these operations, the first relay node is allowed to be selected "in response to a notification message indicating a duration and the duration having elapsed after reception of the notification message" or "in response to a discovery message received from the first relay node including a cell identifier (ID) different from the cell ID of the first relay node". Specific examples are described in the embodiments of FIGS. 5 and 6 as follows.

[0077] In some embodiments, the UE may send to the network node another RRC re - establishment request message (shown as the "second RRC re - establishment request message" for simplicity) and, in response to the transmission of the second RRC re - establishment request message, start another timer for the RRC re - establishment request.

[0078] In some embodiments, the UE may receive from the network node an RRC re - establishment message in response to the first RRC re - establishment request message. In one embodiment, the RRC re - establishment message may be received before sending the second RRC re - establishment request message. In a further embodiment, the RRC re - establishment message may be received after a short duration after sending the second RRC re - establishment request message.

[0079] In some embodiments, in response to the reception of the RRC re - establishment message, the UE may discard the RRC re - establishment message or the UE may apply the RRC re - establishment message and stop the above - mentioned other timer for the RRC re - establishment request. Specific examples are described in the embodiment of FIG. 6 as follows.

[0080] Without departing from the spirit and scope of the present disclosure, those skilled in the art should understand that the order of operations in the exemplary procedure 400 may be changed, and some of the operations in the exemplary procedure 400 may be removed or changed. All other details described in all other embodiments of this application (for example, all details regarding the extended mechanism for the RRC re-establishment procedure) are applicable to the exemplary flowchart 400. Further, the details described in the exemplary flowchart 400 are applicable to all of the embodiments of FIGS. 5 to 8.

[0081] FIG. 5 shows an exemplary flowchart 500 of an RRC re-establishment procedure according to some embodiments of the present disclosure. All the details described in all the above embodiments of the present disclosure are applicable to the embodiment shown in FIG. 5.

[0082] Referring to FIG. 5, in operation 511, a UE 501 (for example, a remote UE or an L2 U2N remote UE) accesses a BS 503 either directly or via an L2 U2N relay UE (for example, a relay UE 502A as shown in FIG. 5, marked as an option). In some embodiments, the BS 503 may send an indication to the UE 501 as to whether an L2 relay node is supported.

[0083] In operation 512, the UE 501 may initiate an RRC re-establishment procedure based on at least one of the following conditions. (1) When detecting an RLF on a master cell group (MCG) link, (2) When detecting an RLF on a sidelink, (3) When receiving a notification message (for example, a NotificationMessageSidelink message) including an indication type (for example, an IndicationType IE) by the UE 501 in the RRC_CONNECTED state, or When the upper layer in the UE 501 in the RRC_CONNECTED state indicates the release of the PC5 unicast link.

[0084] In some embodiments, if the UE 501 is not configured with the conditional reconfiguration configuration associated with the candidate target cell and / or the execution conditions associated with the candidate target cell (e.g., conditional Reconfiguration IE), or if the selected cell is configured by CHO for the first time after a failure, and the UE is not configured with an indication (e.g., attemptCondReconfig IE) to indicate that the UE 501 should execute the conditional reconfiguration configuration associated with the candidate target cell, the UE 501 may release the PC5 relay RLC channel.

[0085] In some embodiments, the UE 501 may be configured with the conditional reconfiguration configuration of the candidate target SpCell and / or the associated execution conditions for conditional handover, conditional PSCell addition, or conditional PSCell change.

[0086] In some embodiments, the UE 501 may be configured with an attemptCondReconfig IE, which is used to indicate that the UE 501 should execute the conditional reconfiguration configuration and / or the associated execution conditions when the selected cell is a target candidate cell configured by conditional handover (CHO) for the first time after a failure (e.g., handover failure).

[0087] In operation 513, the UE 501 performs cell selection, relay selection, and / or relay reselection. Some embodiments assume that one suitable relay UE, e.g., the relay UE 502B as shown in FIG. 5, is selected.

[0088] In operation 514, when one relay UE is selected, the UE 501 transmits an RRC re-establishment request message to the serving cell of the BS 503 via the relay UE 502B and starts a timer (e.g., T301) for the RRC re-establishment request.

[0089] In operation 515, while the timer (e.g., T301) for the RRC re-establishment request is running, the UE 501 may receive a notification message from the relay UE 502B when at least one of the following conditions is satisfied in the relay UE 502B. (1) At the time of Uu RLF in the relay UE 502B, (2) When receiving an RRCReconfiguration including reconfigurationWithSync, (3) At the time of cell reselection of the relay UE 502B, or (4) At the time of RRC connection failure of the relay UE 502B. For example, the RRC connection failure may include RRC connection rejection, expiration of T300, and / or RRC resume failure.

[0090] In some embodiments, the notification message may include an indication type (e.g., IndicationType IE). For example, the indication type may include handover of the relay UE 502B, RLF between the relay UE 502B and the BS 503, cell reselection of the relay UE 502B, and / or RRC connection failure of the relay UE 502B.

[0091] Upon receiving the notification message, the UE 501 may consider that at least one of the following events has occurred. (1) The UE 501 considers that "the selected cell has become inappropriate" upon receiving the notification message. (2) The UE 501 considers that cell selection has occurred upon receiving the notification message. (3) The UE 501 considers that the timer (e.g., T301) for the RRC re-establishment request has expired upon receiving the notification message.

[0092] In operation 516, when at least one of the following conditions (i.e., pre-specified conditions associated with the reception of the notification message) is satisfied and a timer (e.g., T301) for the RRC re-establishment request is running, the UE 501 may stop the timer. (1) Reception of the notification message. (2) The UE 501 deems that "the selected cell becomes inappropriate" upon receiving the notification message. (3) The UE 501 deems that cell selection occurs upon receiving the notification message. (4) The UE 501 deems that a timer (e.g., T301) for the RRC re-establishment request expires upon receiving the notification message.

[0093] In operation 517, after stopping the timer (e.g., T301) for the RRC re-establishment request, the UE 501 enters the RRC idle state.

[0094] In operation 518, after the UE 501 enters the RRC idle state, the UE 501 may initiate a connection establishment procedure. For example, before initiating the connection establishment procedure, the UE 501 may further perform cell selection, cell reselection, relay selection, and / or relay reselection. During cell selection, cell reselection, relay selection, and / or relay reselection, the UE 501 may select a relay node. There may be different embodiments regarding whether the previous relay node (i.e., relay UE 502B) can be selected again. For example, in operation 518, cell (re)selection and relay (re)selection may follow the principle. (1) In some embodiments, when the UE 501 performs cell (re)selection and / or relay (re)reselection, if multiple suitable nodes (including suitable relay nodes and / or suitable cells) are available, the previous relay node (i.e., relay UE 502B) will not be selected. (2) In some embodiments, the duration may be indicated in the notification message sent from relay UE502B to UE501. After the duration has elapsed since receiving the notification message from relay UE502B, the previous relay node (i.e., relay UE502B) is allowed to be reselected for RRC reestablishment purposes. (3) In some embodiments, if a new cell ID is included in the discovery message sent by the previous relay node (i.e., relay UE502B), the previous relay UE is allowed to be selected.

[0095] In some embodiments, after completing the connection establishment procedure, UE501 may send an RRC setup request message to BS503. In some embodiments, BS503 may send an RRC setup message to UE501. Then, after receiving the RRC setup message from BS503, UE501 may enter the RRC connected state.

[0096] Those skilled in the art should understand that, without departing from the spirit and scope of the present disclosure, the order of operations in exemplary procedure 500 may be changed, and some of the operations in exemplary procedure 500 may be removed or changed.

[0097] FIG. 6 shows a further exemplary flowchart 600 of an RRC reestablishment procedure according to some embodiments of the present disclosure. The details described in all of the above embodiments of the present disclosure are applicable to the embodiments shown in FIG. 6.

[0098] Referring to FIG. 6, in operation 611, UE601 (e.g., a remote UE or an L2 U2N remote UE) accesses BS603 via a direct path or via an L2 U2N relay UE (e.g., relay UE602A as shown in FIG. 6, marked as an option). In some embodiments, BS603 may send an indication to UE601 as to whether an L2 relay node is supported.

[0099] In operation 612, the UE 601 may initiate an RRC reestablishment procedure based on at least one of the following conditions. (1) When detecting an RLF on the MCG link, (2) When detecting an RLF on the sidelink, (3) When receiving a notification message (e.g., a NotificationMessageSidelink message) including an indication type (e.g., an IndicationType IE) by the UE 601 in the RRC_CONNECTED state, or (4) When a PC5 unicast link is released as indicated by a higher layer in the UE 601 in the RRC_CONNECTED state.

[0100] In operation 613, the UE 601 transmits an RRC reestablishment request message to the serving cell of the BS 603 via a relay UE (e.g., the relay UE 602B as shown in FIG. 6), and starts a timer (e.g., T301) for the RRC reestablishment request. Some embodiments assume that one suitable relay UE (i.e., the relay UE 602B) is selected in the RRC reestablishment procedure.

[0101] In operation 614, while the timer (e.g., T301) for the RRC reestablishment request is running, when at least one of the following conditions is satisfied in the relay UE 602B, the UE 601 may receive a notification message from the relay UE 602B. (1) When an Uu RLF occurs in the relay UE 602B, (2) When receiving an RRCReconfiguration including reconfigurationWithSync, (3) When cell reselection of the relay UE 602B occurs, (4) When an RRC connection failure occurs in the relay UE 602B. For example, the RRC connection failure may include an RRC connection rejection, expiration of T300, and / or an RRC resume failure.

[0102] In some embodiments, the notification message includes an indication type (e.g., IndicationType IE), and for example, the indication type includes handover of relay UE602B, RLF between relay UE602B and BS603, cell reselection of relay UE602B, and / or RRC connection failure of relay UE602B.

[0103] Upon receiving a notification message from relay UE602B, UE601 may consider that at least one of the following events has occurred. (1) UE601 considers that "the selected cell becomes inappropriate" upon receiving the notification message. (2) UE601 considers that cell selection has occurred upon receiving the notification message. (3) UE601 considers that a timer (e.g., T301) for RRC re-establishment request expires upon receiving the notification message.

[0104] In operation 615, when at least one of the following conditions (i.e., pre-specified conditions associated with the reception of the notification message) is satisfied, if a timer (e.g., T301) for RRC re-establishment request is running, UE601 may stop the timer. (1) Reception of the notification message. (2) Cell change upon receiving the notification message. (3) UE601 considers that "the selected cell becomes inappropriate" upon receiving the notification message. (4) UE601 considers that cell selection has occurred upon receiving the notification message. (5) UE601 considers that a timer (e.g., T301) for RRC re-establishment request expires upon receiving the notification message.

[0105] In operation 615, after the UE 601 stops a timer (e.g., T301) for an RRC re - establishment request, in some embodiments, the UE 601 may start an RRC re - establishment procedure in operation 616. However, in some other embodiments, the UE 601 may not start the RRC re - establishment procedure. That is, operation 616 is an option in the exemplary flowchart 600.

[0106] In operation 617, the UE 601 further performs cell selection, relay selection, and relay reselection for the purpose of RRC re - establishment, and may start a timer (e.g., T311) for relay or cell selection. When a suitable cell or a suitable relay node is selected, the UE 601 may send another RRC re - establishment request message via the suitable relay node and start another timer (e.g., T301) for the RRC re - establishment request. Regarding whether the previous relay node (i.e., relay UE 602B) can be selected again in operation 617, there can be the following different embodiments. For example, in operation 617, cell (re)selection and relay (re)selection may follow the principle. (1) In some embodiments, when the UE 601 performs cell (re)selection, relay selection, and / or relay reselection, if a plurality of suitable nodes (including suitable relay nodes and / or suitable cells) are available, the previous relay node (i.e., relay UE 602B) will not be selected. (2) In some embodiments, a duration may be indicated in a notification message sent from the relay UE 602B to the UE 601. After the duration has elapsed since receiving the notification message from the relay UE 602B, the previous relay node (i.e., relay UE 602B) is allowed to be selected again for the purpose of RRC re - establishment. (3) In some embodiments, if a new cell ID is included in a discovery message sent by the previous relay node (i.e., relay UE 602B), the previous relay UE is allowed to be selected.

[0107] In operation 618, UE 601 may receive from BS 603 an "RRC re - establishment message in response to the RRC re - establishment request message in operation 613". In some embodiments, in operation 617, before transmitting the above - mentioned another RRC re - establishment request message, UE 601 receives an RRC re - establishment message in response to the RRC re - establishment request message in operation 613. In some other embodiments, after UE 601 transmits the above - mentioned another re - establishment request message in operation 617, after a very short elapsed time, UE 601 receives an RRC re - establishment message in response to the RRC re - establishment request message in operation 613.

[0108] In operation 619, UE 601 may adopt operations in different embodiments. In some embodiments, UE 601 may discard the RRC re - establishment message received in operation 618. In some other embodiments, UE 601 may apply the RRC re - establishment message received in operation 618 and stop the above - mentioned timer (e.g., T301) for the RRC re - establishment request in operation 617.

[0109] Those skilled in the art should understand that without departing from the spirit and scope of the present disclosure, the order of operations in the exemplary procedure 600 may be changed, and some of the operations in the exemplary procedure 600 may be removed or changed.

[0110] FIG. 7 shows an exemplary block diagram of an apparatus 700 for an RRC re - establishment procedure according to some embodiments of the present disclosure.

[0111] As shown in FIG. 7, apparatus 700 may include at least one non-transitory computer-readable medium 702, at least one receiving circuit 704, at least one transmitting circuit 706, and at least one processor 708 coupled to the non-transitory computer-readable medium 702, the receiving circuit 704, and the transmitting circuit 706. The at least one processor 708 may be a CPU, a DSP, a microprocessor, or the like. The apparatus 700 may be a network device (e.g., a BS) or a UE (e.g., a remote UE or a relay UE) configured to execute the methods shown above, etc.

[0112] In this figure, elements such as at least one processor 708, the receiving circuit 704, and the transmitting circuit 706 are described in the singular, but the plural is contemplated unless a limitation to the singular is specified. In some embodiments of the present application, the receiving circuit 704 and the transmitting circuit 706 may be combined into a single device such as a transceiver. In some embodiments of the present application, the apparatus 700 may further include an input device, a memory, and / or other components.

[0113] In some embodiments of the present application, the non-transitory computer-readable medium 702 may store computer-executable instructions for causing the processor to implement the method for a remote UE as described above. For example, when executed, the computer-executable instructions cause the processor 708, which is interacting with the receiving circuit 704 and the transmitting circuit 706, to execute the steps for a remote UE as shown above.

[0114] In some embodiments of the present application, the non-transitory computer-readable medium 702 may store computer-executable instructions for causing the processor to implement the method for a relay UE as described above. For example, when executed, the computer-executable instructions cause the processor 708, which is interacting with the receiving circuit 704 and the transmitting circuit 706, to execute the steps for a relay UE as shown above.

[0115] FIG. 8 shows a further exemplary block diagram of an apparatus 800 for an RRC re - establishment procedure, according to some embodiments of the present disclosure.

[0116] Referring to FIG. 8, the apparatus 800, e.g., a BS or a UE, may include at least one processor 802 and at least one transceiver 804 coupled to the at least one processor 802. The transceiver 804 may include at least one separate receiving circuit 806 and transmitting circuit 808, or at least one integrated receiving circuit 806 and transmitting circuit 808. The at least one processor 802 may be a CPU, a DSP, a microprocessor, etc.

[0117] According to some other embodiments of the present application, when the apparatus 800 is a remote UE, the processor 802 is configured to start a radio resource control (RRC) re - establishment procedure, transmit an RRC re - establishment request message to a network node via a relay node via the transceiver 804, start a timer for the RRC re - establishment request in response to the transmission of the RRC re - establishment request message, and stop the timer for the RRC re - establishment request in response to a pre - specified condition associated with the reception of a notification message being met.

[0118] The method of the present disclosure may be implemented on a programmed processor. However, controllers, flowcharts, and modules may also be implemented in general - purpose or special - purpose computers, programmed microprocessors or microcontrollers and peripheral integrated circuit elements, integrated circuits, discrete element circuits, etc., such as hardware electronic or logic circuits, programmable logic devices, etc. Generally, any device having a finite - state machine capable of implementing the flowcharts shown in the figures may be used to implement the processing functions of the present disclosure.

[0119] Although the present disclosure has been described with its specific embodiments, it is clear that many alternative, modified, and variant forms may be apparent to those skilled in the art. For example, the various components of an embodiment may be exchanged, added, or substituted in other embodiments. Also, not all elements of each figure are necessary for the operation of the disclosed embodiments. For example, those skilled in the art of the disclosed embodiments can practice and use the teachings of the present disclosure by simply adopting the elements of the independent claims. Therefore, the embodiments of the present disclosure described herein are to be considered illustrative rather than limiting. Various changes can be made without departing from the spirit and scope of the present disclosure.

[0120] In this specification, the terms "handover" and "path switching" may be used interchangeably. The terms "includes", "including", or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Elements preceded by "a", "an", etc. do not preclude the presence of additional equivalent elements in the process, method, article, or apparatus that includes that element without more constraints. Also, the term "another" is defined as at least a second or more. Terms such as "having" used herein are defined as "including". Expressions such as "A and / or B" or "at least one of A and B" can include any and all combinations of the words listed with that expression. For example, the expression "A and / or B" or "at least one of A and B" can include A, B, or both A and B. Expressions such as "first", "second", etc. are used only to clearly describe the embodiments of the present application and are not used to limit the content of the present application.

Description of Reference Numerals

[0121] 100 Wireless communication system 101A, 101B, 101C, 201A, 301, 501, 601 UEs 102, 103, 202, 503, 603 Bases stations 200 Relay-based wireless communication system, wireless communication system 201B UE, Relay UE 302 Network 502A, 502B, 602A, 602B Relay UEs 700, 800 Devices 702 Non-transitory computer-readable medium 704, 806 Receiving circuits 706, 808 Transmitting circuits 708, 802 Processors 804 Transceiver

Claims

1. A user equipment (UE) for wireless communications, comprising: At least one memory; and at least one processor coupled to the at least one memory, the at least one processor configured to: initiating a first radio resource control (RRC) re-establishment procedure; sending a first RRC re-establishment request message to a network node via a first relay node; starting a first timer for an RRC re-establishment request in response to transmitting the first RRC re-establishment request message; in response to a prespecified condition associated with receiving a notification message being satisfied, stopping a first timer for the RRC re-establishment request; A user equipment configured to cause

2. 2. The user equipment of claim 1, wherein the notification message indicates at least one of a handover of the first relay node, a radio link failure (RLF) between the first relay node and the network node, a cell reselection of the first relay node, or an RRC connection failure of the first relay node.

3. The at least one processor may further include: initiating the first RRC re-establishment procedure; initiation of the first RRC re-establishment procedure, and the UE is not configured with a conditional reconfiguration configuration associated with a candidate target cell; or The UE is not configured with an instruction to indicate that the UE will perform the conditional reconfiguration configuration when the first RRC re-establishment procedure is initiated and a selected cell is configured in a conditional handover (CHO) for the first time after a failure. and releasing configuration information associated with a PC5 relay radio link control (RLC) channel in response to at least one of The user equipment of claim 1 , configured to:

4. The at least one processor may further include: performing at least one of a first cell selection operation, a first relay selection operation, or a first relay reselection operation in response to initiation of the first RRC re-establishment procedure. The user equipment of claim 1, further configured to:

5. The at least one processor may further include: receiving the notification message from the first relay node; The user equipment of claim 1, further configured to:

6. The at least one processor may further include:

2. The user equipment of claim 1, further configured to: enter an RRC idle state in response to the prespecified condition being satisfied or in response to a stop of a first timer for the RRC re-establishment request.

7. The at least one processor may further include: initiating a second RRC re-establishment procedure in response to the prespecified condition being satisfied or in response to stopping a first timer for the RRC re-establishment request. The user equipment of claim 1 , configured to:

8. The user equipment of claim 7, wherein the pre-specified condition comprises a cell change upon the receipt of the notification message.

9. The pre-specified condition is: the receiving of the notification message from the first relay node; the UE, upon receipt of the notification message, deems the selected cell to be unsuitable; the UE deems, upon receipt of the notification message, that a cell selection operation occurs; The UE considers, upon receipt of the notification message, that a first timer for the RRC re-establishment request expires. The user equipment of claim 1 , comprising at least one of:

10. The at least one processor may further include: performing at least one of a second cell selection operation, a second relay selection operation, or a second relay reselection operation after initiating the second RRC re-establishment procedure. The user equipment of claim 7, further configured to:

11. During the at least one of the second cell selection operation, the second relay selection operation, or the second relay reselection operation, The first relay node, Another suitable relay node is available, or Availability of suitable cells is not permitted to be selected in response to The first relay node, the notification message indicates a duration, and the duration has elapsed since the receipt of the notification message; or a discovery message received from the first relay node includes a cell identifier (ID) that is different from a first cell ID of the first relay node; The user equipment of claim 10, wherein the user equipment is allowed to be selected in response to

12. The at least one processor may further include: sending a second RRC re-establishment request message to the network node; starting a second timer for an RRC re-establishment request in response to transmitting the second RRC re-establishment request message; The user equipment of claim 7, further configured to:

13. The at least one processor may further include: receiving, from the network node, an RRC re-establishment message in response to the first RRC re-establishment request message; The user equipment of claim 7, further configured to:

14. In response to receiving the RRC re-establishment message, the at least one processor causes the UE to: discarding the RRC re-establishment message; or applying the RRC re-establishment message and stopping a second timer for the RRC re-establishment request. The user equipment of claim 13, further configured to:

15. 1. A method performed by a user equipment (UE), comprising: initiating a first radio resource control (RRC) re-establishment procedure; sending a first RRC re-establishment request message to a network node via a first relay node; starting a first timer for an RRC re-establishment request in response to transmitting the first RRC re-establishment request message; in response to a prespecified condition associated with receiving a notification message being satisfied, stopping a first timer for the RRC re-establishment request; A method comprising:

16. A processor for wireless communications, comprising: At least one controller coupled to the at least one memory wherein the at least one controller causes the processor to: initiating a first radio resource control (RRC) re-establishment procedure; sending a first RRC re-establishment request message to a network node via a first relay node; starting a first timer for an RRC re-establishment request in response to transmitting the first RRC re-establishment request message; in response to a prespecified condition associated with receiving a notification message being satisfied, stopping a first timer for the RRC re-establishment request; A processor configured to:

17. The processor of claim 16, wherein the notification message indicates at least one of a handover of the first relay node, a radio link failure (RLF) between the first relay node and the network node, a cell reselection of the first relay node, or an RRC connection failure of the first relay node.

18. The at least one controller, wherein the processor: initiating the first RRC re-establishment procedure; initiation of the first RRC re-establishment procedure, and the UE is not configured with a conditional reconfiguration configuration associated with a candidate target cell; or The UE is not configured with an instruction to indicate that the UE will perform the conditional reconfiguration configuration when the first RRC re-establishment procedure is initiated and a selected cell is configured in a conditional handover (CHO) for the first time after a failure. and releasing configuration information associated with a PC5 relay radio link control (RLC) channel in response to at least one of 20. The processor of claim 16, configured to:

19. The at least one controller, wherein the processor: performing at least one of a first cell selection operation, a first relay selection operation, or a first relay reselection operation in response to initiation of the first RRC re-establishment procedure. The processor of claim 16 , further configured to:

20. The at least one controller, wherein the processor: initiating a second RRC re-establishment procedure in response to the pre-specified condition being satisfied or in response to stopping a first timer for the RRC re-establishment request; and performing at least one of a second cell selection operation, a second relay selection operation, or a second relay reselection operation after initiating the second RRC re-establishment procedure; The processor of claim 16 , further configured to:

Images