Enhanced monitoring of Radio Resource Control (RRC) configuration procedures from PC5 in New Radio (NR) Sidelink (SL)

Abstract

For example, systems, methods, apparatus, and computer program products are provided for monitoring a PC5 interface to radio resource control (PC5-RRC) configuration procedure in new radio (NR) sidelink (SL) mode 1. One method may include configuring an SL user equipment (UE) with behavior for processing and monitoring PC5-RRC procedures and one or more associated timers, taking into account the state of the interface between the SL UE and the network node.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 007,450, filed April 9, 2020. The entire contents of this previously filed application are incorporated herein by reference in their entirety.

[0002] Some example embodiments may relate generally to mobile or wireless communications systems, such as Long Term Evolution (LTE) or fifth generation (5G) radio access technologies or new radio (NR) access technologies, or other communications systems. For example, particular examples may relate to systems and / or methods for monitoring PC5 radio resource control (RRC) configuration procedures in new radio (NR) sidelink (SL) mode 1. [Background technology]

[0003] Examples of mobile or wireless communication systems may include Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN), Long Term Evolution (LTE) Evolved UTRAN (E-UTRAN), LTE-Advanced (LTE-A), MultiFire, LTE-A Pro, and / or fifth-generation (5G) radio access technology or new radio (NR) access technology. 5G wireless systems refer to the next generation (NG) of radio systems and network architectures. 5G systems are primarily built on 5G new radio (NR), but 5G (or NG) networks can also be built on E-UTRA radio. NR is estimated to provide bit rates on the order of 10–20 Gbit / s or more and support at least service categories such as enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC). NR is expected to provide extreme broadband and ultra-robust low-latency connectivity, as well as large-scale networks to support the Internet of Things (IoT). With the spread of IoT and machine-to-machine (M2M) communications, there is a growing need for networks that meet the requirements of low power consumption, low data rates, long battery life, etc. Next-generation radio access network (NG-RAN) represents the RAN for 5G and can provide both NR and LTE (and LTE-Advanced) radio access. It should be noted that in 5G, the node capable of providing radio access functionality to user equipment (i.e., similar to Node B, NB, in UTRAN, or evolved NB, eNB, in LTE) may be named Next Generation NB (gNB) if built on NR radio, or Next Generation eNB (NG-eNB) if built on E-UTRA radio. Summary of the Invention [Means for solving the problem]

[0004] A first embodiment is directed to a method that may be performed by a network node, which may comprise the network node configuring a Sidelink (SL) User Equipment (UE) with operations to process and monitor PC5-Radio Resource Control (RRC) procedures and one or more associated timers by taking into account the state of an interface between the SL UE and the network node (e.g., a Uu link).

[0005] For example, a variant may involve configuring the SL UE to handle the timers used to monitor the PC5RRC (re)configuration procedure.

[0006] Alternatively, the timer may be a T400 timer. According to variants, the configuration may include configuring the SL UE with multiple values ​​for a timer or using multiple different timers associated with the same PC5-RRC procedure. In some variants, different values ​​or timers may be used depending on the conditions experienced from the interface between the SL UE and the network node if there is a physical layer problem or a connection re-establishment procedure or a handover procedure over the interface. In a variant, the interface may be a Uu interface.

[0007] In some variations, one value and / or timer may be used when no physical layer problem over the interface is detected and no connection re-establishment and / or handover procedure is initiated. In some variations, another value and / or timer may be configured to be used when a physical layer problem is detected, etc. According to some variations, different values ​​and / or timers may be set to be used when a connection re-establishment is initiated, etc. In some variations, different values ​​and / or timers may be set to be used when, for example, a handover procedure is initiated. In some variants, different values ​​and / or timers may be configured to be used, for example, when an SL UE uses an exceptional resource pool to transmit an RRC reconfiguration sidelink message.

[0008] In a variant, the configuration may include configuring the SL UE to extend a timer (e.g. a T400 timer) upon detection of a physical layer problem or initiation of a connection re-establishment or handover procedure when an RRC reconfiguration sidelink message is sent to lower layers and the timer is started. According to some variants, the configuration may include configuring the SL UE with an extension value corresponding to conditions such as the occurrence of a physical layer problem, the execution of a connection re-establishment or handover procedure, the use of an exceptional resource pool, etc. In one variant, the timer extension may relate to a timer configured to monitor a physical layer recovery procedure or a connection re-establishment or handover procedure.

[0009] A second embodiment is directed to a method that may be performed by an SL UE, such as an SL TX UE. The method may include determining whether there is a radio problem at an interface between the SL TX UE and a network node. If it is determined that there is no radio problem at the interface, the method may include generating or formulating an RRC reconfiguration sidelink message.

[0010] In a variant, determining whether there is a radio problem may include determining whether there is a physical layer problem or a connection re-establishment or handover procedure via the interface between the SL UE and the network. Furthermore, in a variant, if it is determined that there is no physical layer problem or a connection re-establishment or handover procedure via the interface, the method may include sending an RRC reconfiguration sidelink message to lower layers and starting timer T400.

[0011] In a variant, determining whether there is a radio problem may include determining at least one of whether an exceptional resource pool is configured and / or whether the UE received resources of the configured grant type before the radio problem was detected.

[0012] According to one variant, the construction of the RRC reconfiguration sidelink message may be performed in the RRC layer of the SL UE. As an example, the interface between the SL UE and the network may be a Uu interface.

[0013] In one variant, the transmission may involve the RRC layer of the SL UE sending an RRC reconfiguration sidelink message to lower layers only if there is no physical layer problem or a connection re-establishment or handover procedure over the Uu interface.

[0014] According to a variant, if it is determined that there is a physical layer problem or a connection re-establishment or handover procedure over the interface, the method may include not generating or constructing an RRC Reconfiguration Sidelink message and not starting a timer used to monitor the PC5 RRC (re)configuration procedure. As a variant, the timer may be a T400 timer. That is, in a variant, if there is a physical layer problem or a connection re-establishment or handover procedure over the interface (e.g., Uu interface), the RRC layer of the SL UE does not generate or construct an RRC Reconfiguration Sidelink message and the timer is not started.

[0015] In variants, this determination may include checking timer(s) configured to monitor physical layer (e.g., Uu physical layer) recovery procedures and / or connection re-establishment procedures and / or handover procedures. For example, in some variants, the check may include checking whether the T310 timer is running, which indicates that the SL UE has detected consecutive N310 out-of-sync indications from lower layers on the Uu interface. In variants, if it is determined that there is a physical layer problem (e.g., the construction may include constructing an RRC Reconfiguration sidelink message after the physical layer problem is resolved, e.g., when the T310 timer is stopped).

[0016] In another variant, if it is determined that there is a connection re-establishment procedure or a handover procedure over the interface, the constructing may include constructing an RRC reconfiguration sidelink message after the connection re-establishment or handover to the target cell.

[0017] A third embodiment is directed to a method that may be performed by an SL UE. The method may include generating or constructing an RRC Reconfiguration sidelink message and starting a timer used to monitor a PC5 RRC (re)configuration procedure. The method may include detecting, after constructing the RRC Reconfiguration sidelink message and starting the timer, that there is a radio problem on the interface between the SL UE and the network node. The method may include maintaining a value of the timer until the radio problem on the interface is resolved.

[0018] Alternatively, detecting that there is a radio problem on the interface may include detecting a physical layer problem or initiating a connection re-establishment procedure or a handover procedure over the Uu interface.

[0019] In another variation, if a physical layer problem is detected or a connection re-establishment or handover procedure is initiated after constructing the RRC reconfiguration sidelink message and starting a timer (e.g., T400 timer), the method may include retaining the value of the timer until the physical layer problem is resolved, the connection re-establishment or handover procedure is completed, or the SL UE is in RRC idle mode. In this variation, once the physical layer problem is resolved or a connection re-establishment is performed with the same serving cell, the method may include restarting the timer (e.g., T400 timer) using the existing value.

[0020] In some variations, the method may include suspending a timer (eg, a T400 timer) when a connection re-establishment procedure or a handover procedure is initiated. If the connection re-establishment or handover procedure is successful with the new serving cell, or if the connection re-establishment or handover is not successful and the SL UE enters RRC idle mode, the method may include checking whether the PC5 configuration obtained from the new serving cell (if the connection re-establishment and handover is successful) or the SIB / preconfiguration (if entering idle mode) conforms to the configuration in the constructed RRC reconfiguration sidelink message. If so, the method may include restarting a timer (e.g., T400 timer) with the existing value. In case of entering idle mode and switching to SL mode 2, a possible method is to start a timer (e.g., T400 timer) with the existing value and use SL mode 2 once the SL UE has detected this. If not, the method may include constructing a new RRC reconfiguration sidelink message accordingly and restarting the timer with the original / initial value (e.g., T400 value is reset and T400 is restarted).

[0021] In one variant, if the connection re-establishment procedure or the handover procedure fails, the method may include switching to SL mode 2. In this variant, the method may include checking whether the configuration obtained from the SIB / preconfiguration complies with the configuration of the constructed RRC Reconfiguration sidelink message. If compliant, the method may include starting a timer (e.g., T400 timer). The method may further include starting a timer (e.g., T400 timer) with an existing value once sensing results are available for using SL mode 2. If not compliant, the method may include constructing a new RRC Reconfiguration sidelink message accordingly and starting a timer (e.g., T400 timer). The method may further include starting a timer (e.g., T400 timer) once sensing results are available for using SL mode 2. Furthermore, this variant may include restarting the timer (e.g., T400 timer) with an original / initial value upon transmission of the new RRC Reconfiguration sidelink message to lower layers.

[0022] In certain variants, the SL UE may be configured by the network with multiple values ​​of a timer (e.g., T400 timer) or multiple different timers associated with the same PC5-RRC procedure. According to some examples, different values ​​and timers may be used depending on the conditions experienced from the interface between the SL UE and the network (e.g., Uu interface), for example, if there is a physical layer problem or a connection re-establishment procedure or handover procedure over the (Uu) interface.

[0023] In another variant, the SL UE may be configured by the network to extend a timer (e.g., T400 timer) upon detection of a physical layer problem or initiation of a connection re-establishment or handover procedure when an RRC reconfiguration sidelink message is sent to lower layers and the timer (e.g., T400 timer) is started. According to some examples, the SL UE may be configured with an extension value corresponding to conditions such as: a physical layer problem occurred, a connection re-establishment or handover procedure was performed, an exceptional resource pool was used, etc. In one variant, the timer extension may correspond to and be associated with a timer configured to monitor a physical layer recovery procedure or a connection re-establishment or handover procedure.

[0024] A fourth embodiment is directed to an apparatus including at least one processor and at least one memory configuring computer program code, the at least one memory and the computer program code, together with the at least one processor, can be configured to cause the apparatus to perform a method according to at least the first embodiment, the second embodiment, the third embodiment, and / or any other embodiment described herein, or a variation of any of the above.

[0025] A fifth embodiment is directed to an apparatus that may include circuitry configured to perform a method according to the first embodiment, the second embodiment, the third embodiment, and / or any other embodiment described herein, or a variation of any of the above.

[0026] A sixth embodiment is directed to an apparatus that may include means for carrying out a method according to the first embodiment, the second embodiment, the third embodiment, and / or any other embodiment described herein, or a variation of any of the above.

[0027] A seventh embodiment is directed to a non-transitory computer-readable medium including program instructions stored thereon for performing a method according to at least the first embodiment, the second embodiment, the third embodiment, and / or any other embodiment described herein, or any variation thereof.

[0028] For a proper understanding of the exemplary embodiments, reference should be made to the accompanying drawings. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 illustrates an example signaling diagram illustrating example operations for transmitting a Radio Resource Control (RRC) reconfiguration sidelink message (RRCReconfigurationSidelink message) using SL mode 1 according to one embodiment. [Figure 2] FIG. 2 illustrates an example in which a UE experiences a physical layer problem, according to one embodiment. [Figure 3] FIG. 3 illustrates an example of resolving a radio problem by re-establishing an RRC connection to a new cell, according to one embodiment. [Figure 4] FIG. 4 illustrates an example of SL transmit (TX)-UE entering RRC-IDLE state and switching to SL mode 2 according to one embodiment. [Figure 5a] FIG. 5a shows an example flow diagram of a method according to an example embodiment. [Figure 5b] FIG. 5b shows an example flow diagram of a method according to an example embodiment. [Figure 5c] FIG. 5c shows an example flow diagram of a method according to an example embodiment. [Figure 6] 1A shows an example of a block diagram of an apparatus according to an embodiment; FIG. 1B shows an example of a block diagram of an apparatus according to an embodiment; and FIG. 1C shows an example of a block diagram of an apparatus according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0030] It will be readily understood that the components of particular example embodiments, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Accordingly, the detailed description of several example systems, methods, apparatuses, and computer program products for monitoring RRC (PC5-RRC) configuration procedures from a PC5 interface in NR SL Mode 1 is not intended to limit the scope of the particular examples, but rather is representative of selected examples.

[0031] The features, structures, or characteristics of the exemplary embodiments described throughout this specification may be combined in any suitable manner in one or more exemplary embodiments. For example, the use of the phrase "particular embodiment," "some embodiments," or other similar phrases throughout this specification refers to the fact that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment. Thus, the appearances of the phrases "particular embodiment," "some embodiments," "other embodiments," or other similar phrases throughout this specification do not necessarily all refer to the same group of embodiments, but rather the described features, structures, or characteristics may be combined in any suitable manner in one or more example embodiments.

[0032] Moreover, where appropriate, different functions or procedures described below may be performed in different orders or simultaneously. Furthermore, where appropriate, one or more of the described functions or procedures may be optional or combined. Accordingly, the following description should be considered illustrative of the principles and teachings of particular exemplary embodiments, and not limiting thereof.

[0033] Certain embodiments may relate to the 3rd Generation Partnership Project (3GPP) NR Sidelink (SL) for Release-16 and later. The purpose of NR SL is to provide Highly Reliable and Low Latency Communications (HRLLC), for example, to support advanced Vehicle-to-Everything (V2X) use cases.

[0034] NR V2X is used to provide advanced V2X services, while LTE V2X is intended to provide basic V2X services. The 3GPP Release-16 NR SL specifications (e.g., 3GPP TS 38.331) indicate that the actions associated with sending a sidelink RRC reconfiguration (RRCReconfigurationSidelink) message include the UE configuring the contents of the RRCReconfigurationSidelink message, as described below.

[0035] For example, for each SL data radio bearer (DRB) to be released by sl-ConfigDedicatedNR, system information block type x (SIBX), SidelinkPreconfigNR, or configuration by higher layers, the UE may configure the slrb-PC5-ConfigIndex included in the slrb-ConfigToReleaseList corresponding to the SL DRB. For example, for each SL DRB established or modified by receiving sl-ConfigDedicatedNR, SIBX, or SidelinkPreconfigNR: the UE may configure the SLRB-Config included in the slrb-ConfigToAddModList according to the sl-RadioBearerConfig and sl-RLC-BearerConfig corresponding to the received SL DRB. For each NR SL measurement and reporting to be configured, the UE may configure the sl-MeasConfig according to the stored NR SL measurement configuration information. The UE may submit an RRCReconfigurationSidelink message to lower layers for transmission and start timer T400, which is used to monitor the performance of the PC5 RRC (re)configuration procedure.

[0036] Therefore, the above procedure shows that when configuring or reconfiguring PC5-RRC, timer T400 is started to detect problems that occur during the PC5 (re)configuration procedure. The value of T400 may be defined by the network in the SL-ConfigDedicatedNR, SIBX, or SidelinkPreconfigNR information elements (e.g., t400-r16ENUMERATED{ms100, ms200, ms300, ms400, ms600, ms1000, ms1500, ms2000}). If T400 expires and no RRCReconfigurationSidelink message feedback (i.e., RRCReconfigurationCompleteSidelink message or RRCReconfigurationFailureSidelink message) has been received, the PC5-RRC connection is handled by the Radio Link Failure (RLF) procedure. Therefore, the TX UE detects a PC5-RRC RLF when T400 expires and performs the same actions as an RLF. This means that the TX UE releases the PC5 link and deletes the associated configuration of this link.

[0037] Some timers related to the relevant RRC procedures on the Uu and PC5 interfaces are shown in Table 1 below.

[0038] [Table 1]

[0039] Figure 1 is an example signaling diagram illustrating an example operation of sending an RRCReconfigurationSidelink message using SL mode 1 (i.e., in mode 1, initiating a UE requires requesting SL transmission resources from the serving network). As shown in the example of Figure 1, NR SL in mode 1 requests SL resources from the network to send the RRCReconfigurationSidelink message, as compared to the Uu interface.

[0040] Note that in this disclosure, the time period may be referred to as t_SL_grant. As shown in the example of Figure 1, t_SL_grant may be the time it takes for an SL connection to acquire resources in the system.

[0041] In SL mode 1, t_SL_grant may depend on the radio conditions of the Uu link and congestion on the Uu interface. For example, after the RRCReconfigurationSidelink message is constructed and passed to lower layers for transmission, timer T400 may be started. The UE may then need to request SL resources, for example, using a buffer status report, a scheduling request, or a random access procedure. However, if there are radio link problems from the Uu interface and no exceptional resource pool exists, the UE may first need to resolve the Uu radio link problem (e.g., perform an RRC reconfiguration procedure) before obtaining SL resources from the network. Therefore, if the Uu radio link problem is not resolved before T400 expires, the UE may not be able to send the RRCReconfigurationSidelink message before T400 expires. Also, if the radio link problem is resolved before T400 expires, the remaining time until expiration may not be sufficient to perform the SL RRC reconfiguration procedure. As used herein, a radio link problem may refer to a problem, condition, or state over the Uu interface that prevents the UE from requesting SL resources from the network, such as, for example, the occurrence of a physical layer problem, the execution of a connection re-establishment procedure and / or a handover procedure.

[0042] If an exceptional resource pool is configured, if a Mode 1 UE experiences a problem in which it cannot request sidelink resources from the network, the UE may send an RRCReconfigurationSidelink message using the configured exceptional resource pool. However, because the UE must randomly select resources from the exceptional resource pool, good sidelink performance cannot be ensured. Therefore, in this case, timer T400 may expire due to poor performance using the exceptional resource pool. Because the exceptional resource pool is only used temporarily and the UE later returns to normal operation, for example, requesting resources from the network or even switching to sensing-based resource selection in Mode 2, it is unreasonable to determine sidelink performance by monitoring the temporary performance while the exceptional resource pool is in use.

[0043] If T400 expires, the TX-UE may regard it as a PC5-RRC RLF and release the PC5 radio link. In this case, V2X service between two SL UEs cannot be supported via PC5. However, this is not actually due to a PC5 radio link problem, but rather to a Uu interface radio link problem. The UE may recover by resolving the physical layer problem, re-establishing the RRC connection with a new serving cell, handing over to the target cell, or entering RRC idle mode (e.g., T301, T310, or T311 expiration). In this case, the TX-UE can actually continue connecting and communicating with PC5. Therefore, it may be desirable to avoid PC5-RRC RLFs triggered by T400 expiration due to Uu radio link problems whenever possible.

[0044] Note that the reason for using the T400 timer may include timely detection of PC5 connection problems. The current 3GPP V2X discussion does not address the discrepancy between the generation of the RRCReconfigurationSidelink message in the TX-UE and its actual transmission to the peer UE, and the corresponding discrepancy in the T400 timer. However, setting the timer T400 to a large value may prevent timely detection of problematic PC5 connections, which may have some impact on the system. For example, considering the worst-case scenario from the Uu interface (which is also not easy to predict) to set T400, the Tx UE may wait longer than necessary to perform RLF / RLM. The timer T400 was introduced to monitor SL performance and should not be used to monitor the Uu link, which is handled by other timers / procedures. Setting the timer T400 too large has the same effect as not using the timer at all. Therefore, the purpose of introducing the timer T400 is lost. Furthermore, setting the timer T400 to its maximum value (e.g., 2 seconds) does not solve the above problem. On the other hand, increasing the value of T400 will delay the detection of problems on the PC5 link.

[0045] Certain example implementations may be directed to at least addressing the difficulty of timer configuration for monitoring SL RRC setup procedures in NR SL Mode 1. For example, one or more embodiments may provide new UE behavior regarding handling of PC5 RRC procedures and associated timers by taking into account Uu link conditions / issues.

[0046] In one example, the RRC layer of the sidelink TX-UE (e.g., the initiating TX-UE) may construct and send an RRCReconfigurationSidelink message to lower layers if there are no radio issues (e.g., no physical layer issues detected or no connection re-establishment or handover procedures performed) over the Uu interface, thereby preventing the UE from requesting SL resources from the network. For example, in one embodiment, the RRC layer of the TX UE may construct and send an RRCReconfigurationSidelink message to lower layers only if there are no physical layer issues or no connection re-establishment or handover procedures over the Uu interface. Otherwise, in one embodiment, the RRC layer of the TX-UE should not present an RRCReconfigurationSidelink message to lower layers and therefore should not start timer T400 in this case. Therefore, in this case, an SL reconfiguration failure due to a Uu interface issue is not detected. The PC5RRC (re)configuration procedure is initiated when the physical layer problem on the Uu interface is resolved, or when a connection re-establishment procedure or handover procedure over the Uu interface is performed, or when the Tx UE goes into RRC idle mode.

[0047] For example, the TX-UE may check whether timer T310 is running, indicating that the TX-UE has detected consecutive N310 out-of-sync indications from lower layers on the Uu interface. Therefore, if timer T400 is started without noticing that timer T310 is running, T400 may expire before the physical layer problem is resolved, leading to the unreasonable result of the PC5 link being released, since it does not reflect the state of the PC5 link. In this case, the TX-UE should construct an RRCReconfigurationSidelink message after the physical layer problem is resolved, e.g., when T310 is stopped.

[0048] The same principle may apply when the TX-UE is about to perform a Uu connection re-establishment procedure (e.g., when T301 or T311 is running). In this case, the TX-UE cannot obtain SL resources from the network before the Uu connection is re-established. Therefore, T400 should not be started in this case to avoid it expiring before the Uu connection establishment is complete, since the PC5 link will be released when T400 expires. Furthermore, if the UE re-establishes a Uu connection to a new cell, it may obtain new PC5 settings from the new cell. Therefore, it makes sense to wait and construct the RRCReconfigurationSidelink message after the Uu connection is re-established.

[0049] In another example, upon receiving an RRCReconfiguration message containing reconfigurationWithSync, the UE starts timer T304 and performs a handover to the corresponding special cell (SpCell). Therefore, the UE cannot request sidelink resources from the network before the handover procedure is successful. Again, it makes sense to wait and construct the RRCReconfigurationSidelink message after the handover procedure, since the UE may acquire new PC5 settings from the target cell.

[0050] In another example, if the TX-UE detects a Uu physical layer problem or initiates a Uu connection re-establishment or handover procedure after constructing an RRCReconfigurationSidelink message and initiating T400, the TX-UE may retain the value of timer T400 until the Uu physical layer problem is resolved, the Uu connection re-establishment or handover procedure is completed, or the UE enters RRC idle mode. For example, if the TX-UE detects a physical layer problem (e.g., timer T310 starts or radio channel conditions are worse than a configured threshold), timer T400 is suspended (i.e., T400 is stopped but not reset to its initial value). If the Uu physical layer problem is resolved in the same serving cell (e.g., T310 stops or radio channel conditions are better than a configured threshold), T400 can continue to run.

[0051] If the TX-UE initiates a Uu connection re-establishment procedure (e.g., due to an RLC failure due to the maximum number of retransmissions over the Uu interface being reached, or due to a handover failure) or initiates a handover procedure, timer T400 must also be suspended. If the Uu re-establishment is successful on the same serving cell, T400 can continue to run. If the Uu re-establishment or handover is successful on a new serving cell, or if the UE enters RRC idle mode due to a Uu re-establishment or handover failure, the TX-UE may check whether the PC5 configuration obtained from the new serving cell (if the Uu re-establishment is successful) or SIB / pre-configuration (if idle mode was entered) complies with the configuration in the constructed RRCReconfigurationSidelink message. If so, timer T400 may continue to run. If the UE entered idle mode and switched to SL mode 2, T400 continues to run and uses SL mode 2 once sensing results are available in the TX-UE. If not, the UE may construct a new RRCReconfigurationSidelink message accordingly and restart timer T400 (i.e., the value of T400 is reset to 0 and T400 is started again) once the sensing result for using SL mode 2 is available. For example, in this case the UE may construct a new RRCReconfigurationSidelink message and start timer T400 again upon transmission of the new RRCReconfigurationSidelink message.

[0052] For example, if the Uu connection re-establishment procedure or handover procedure fails, the UE may switch to SL mode 2 (i.e., UE autonomous resource selection mode). In this case, the TX-UE may check whether the configuration obtained from the SIB / preconfiguration complies with the configuration of the constructed RRCReconfigurationSidelink message. If so, timer T400 may continue to run once the sensing result for the UE to use SL mode 2 is available. If not, the TX-UE may construct a new RRCReconfigurationSidelink message accordingly once the sensing result for the UE to use SL mode 2 is available. The UE may also start timer T400 again once it sends a new RRCReconfigurationSidelink message to lower layers.

[0053] FIG. 2 illustrates an example in which a UE experiences a physical layer problem. In the example of FIG. 2, T400 begins at t0 after RRC sends an RRCReconfigurationSidelink message to lower layers. At t1, the SL TX-UE experiences a physical layer problem (e.g., T310 begins). Therefore, the SL TX-UE maintains T400, e.g., T400=T1. At a later point in time, e.g., t2, the radio problem is resolved (e.g., T310 stops) and the SL TX-UE is able to communicate with the same serving cell as before. Therefore, the SL TX-UE no longer maintains T400 and continues running from T400=T1. At t3, the SL TX-UE receives a feedback message from the peer UE. Thus, in this example embodiment, T400 runs for periods T1 and T2, but is not used to monitor the Uu link problem procedure (i.e., between t1 and t2), which is handled by other timers (e.g., T310). As long as T1+T2 is less than the configured value of timer T400, the PC5 RRC (re)configuration procedure is considered successful, preventing the UE from declaring RLF and releasing the PC5 connection due to a Uu problem.

[0054] FIG. 3 illustrates an example of resolving radio issues by reestablishing an RRC connection or handing over to a new cell. As shown in the example of FIG. 3, at t2, the SL TX-UE reestablishes or handovers the RRC connection to a new cell. In this case, at t3, the SL TX-UE checks whether the new configuration from the new cell complies with the RRCReconfigurationSidelink message generated at t0. If not, it must generate a new RRCReconfigurationSidelink message at t4 according to the new configuration obtained from the new cell, as shown in the example of FIG. 3. Also, timer T400 starts from its initial value. In this case, as long as T2 is less than the timer T400 setting, the PC5 RRC (re)configuration procedure is considered successful, and the UE will no longer declare RLF and release the PC5 connection due to a Uu issue. If the configuration from the new cell complies with the RRCReconfigurationSidelink message generated at t0, the timer can continue from T400 = T1 (note that this case is not shown in the example of FIG. 3).

[0055] FIG. 4 illustrates an example in which an SL TX-UE enters the RRC-IDLE state (e.g., due to expiration of T301, T310, or T311) and switches to SL mode 2. As shown in the example of FIG. 4, the UE can read the SIB / preconfiguration at t3 to check whether the RRCReconfigurationSidelink message generated at t0 complies with the configuration obtained from the new state. If not, as shown in the example of FIG. 4, the UE can generate a new RRCReconfigurationSidelink message and start timer T400 from its initial value once the sensing result is available, e.g., at t4. In this case, as long as T2 is less than the configured value of timer T400, the PC5 RRC (re)configuration procedure is considered successful, and the UE will no longer declare RLF and release the PC5 connection due to a Uu issue.

[0056] In yet another embodiment, the TX-UE can be configured with multiple values ​​for T400 or multiple different T400-like timers associated with the same PC5-RRC procedure. Different values ​​or timers can be used / configured depending on various conditions arising from the Uu interface, such as when there is a physical layer problem or a connection re-establishment or handover procedure over Uu. For example, one value or timer can be used when no Uu physical layer problem is detected and Uu connection re-establishment and handover are not initiated. Another value or timer can be configured to be used when a Uu physical layer problem is detected. In this case, upon detecting such a physical layer problem, the RRC layer updates the value and uses it to detect T400 expiration in this special case. Another value or timer can be configured to be used when a Uu connection re-establishment is initiated (e.g., when a handover procedure is initiated). Another value or timer can be configured to be used when the SL TX-UE sends an RRCReconfigurationSidelink message using an exceptional resource pool. Note that multiple values ​​for T400 or multiple different T400-like timers can be applied if Uu radio problems are detected before or after the transmission of the RRCReconfigurationSidelink message to lower layers. Thus, with this approach, different values ​​or timers used to monitor the PC5RRC (re)configuration procedure can be set / updated depending on different radio conditions on the Uu interface.

[0057] In another embodiment, the TX-UE may be configured to extend timer T400 upon detection of a Uu physical layer problem or initiation of a Uu re-establishment or handover procedure, if an RRCReconfigurationSidelink message is sent to lower layers and initiates T400. According to some examples, the network may configure the UE with an extension value corresponding to the above conditions, such as when a Uu physical layer problem occurs, when a Uu connection re-establishment is performed, when a handover procedure is performed, when an exceptional resource pool is used, etc. In one example, the timer extension may be related to a timer configured to monitor a Uu physical layer recovery procedure or a Uu connection re-establishment or handover procedure. For example, if the TX-UE is configured with a constant T0 for T400 and constants T1, T2, and T3 for detecting the expiration of T301, T310, and T311, then: If the TX-UE detects a physical layer problem that triggers the start of T310, the constant for T400 may be extended as (T0 + T2). If the physical layer problem cannot be resolved and T310 expires, the TX-UE may initiate a Uu connection re-establishment procedure, which includes a procedure for selecting a suitable cell and another procedure for requesting RRC re-establishment over the Uu interface. In this case, the constant T400 may be extended as (T0+T2+T3+T1). In one example embodiment, the TX-UE may also initiate the Uu connection re-establishment procedure due to other triggers (e.g., RLC failure when the maximum number of retransmissions is reached). In this case, the constant T400 may be extended as (T0+T3+T1). It should be noted that the above examples do not limit the scope of this embodiment, but only serve as some examples to make this embodiment easier to understand.

[0058] It should be noted that, according to certain embodiments, an RRCReconfigurationSidelink message provided by the RRC layer to lower layers is considered to have been sent.

[0059] 5a illustrates an example flow diagram of a method related to monitoring PC5-RRC configuration procedures, e.g., in NRSL mode 1, according to one example embodiment. In certain example embodiments, the flow diagram of FIG. 5a may be performed by a network entity or network node of a communications system, such as LTE or 5GNR. For example, in some example embodiments, the network node performing the method of FIG. 5a may include a base station, an eNB, a gNB, and / or an NG-RAN node, etc.

[0060] As shown in the example of FIG. 5a, the method may include, at 500, configuring the SL UE with operations related to processing and monitoring of PC5RRC procedures and associated timers, taking into account Uu link conditions / problems.

[0061] In one embodiment, configuration 500 may include configuring the SL UE to allow the RRC layer to construct and send an RRCReconfigurationSidelink message to lower layers when there are no radio problems over the Uu interface (e.g., no physical layer problems are detected, no connection re-establishment or handover procedures are performed), thereby preventing the SL UE from requesting SL resources from the network node. For example, in an embodiment, the RRC layer of the SL UE may be configured to construct and send an RRCReconfigurationSidelink message to lower layers only when there are no physical layer problems or connection re-establishment or handover procedures over the Uu interface. Otherwise, in one embodiment, configuration 500 may include configuring the SL UE so that the RRC layer does not present an RRCReconfigurationSidelink message to lower layers, and therefore, timer T400 should not be started in this case.

[0062] In another embodiment, configuration 500 may include configuring the SL UE to retain the value of timer T400 if the SL UE detects a Uu physical layer problem or initiates a Uu connection re-establishment or handover procedure after constructing an RRCReconfigurationSidelink message and initiating T400, until the Uu physical layer problem is resolved, the Uu connection re-establishment or handover procedure is completed, or the SL UE enters RRC idle mode. For example, if the SL UE detects a physical layer problem (e.g., timer T310 starts or radio channel conditions are worse than a configured threshold), the SL UE is configured to suspend timer T400 (i.e., T400 is stopped but not reset to its initial value). If the Uu physical layer problem is resolved with the same serving cell (e.g., T310 stops or radio channel conditions are better than a configured threshold), the SL UE is configured to restart timer T400 so that it can continue running.

[0063] For example, in one embodiment, configuration 500 may include configuring the SL UE for handling a timer (e.g., T400 timer) used to determine when to perform an SL reconfiguration failure procedure. In one embodiment, configuration 500 may include configuring the SL UE with multiple values ​​for a timer (e.g., T400) or multiple different similar timers associated with the same PC5-RRC procedure. In some examples, different values ​​or timers may be used depending on conditions experienced at the interface between the SL UE and the network (e.g., Uu interface) in the event of a physical layer problem or a connection re-establishment or handover procedure over the (Uu) interface. For example, one value or timer may be used when no physical layer problem is detected and no connection re-establishment is initiated. A different value or timer may be configured to be used when, for example, a physical layer problem is detected. In this case, when such a physical layer problem is detected, the RRC layer may update a constant used to detect expiration of a timer (e.g., T400 timer). A different value or timer may be configured to be used when, for example, a connection re-establishment is initiated. For example, different values ​​or timers may be configured to be used when an SL UE transmits an RRC reconfiguration sidelink message using an exceptional resource pool.

[0064] In one embodiment, the configuration 500 may include configuring the SL UE to extend a timer (e.g., a T400 timer) upon detection of a physical layer problem or upon initiation of a connection re-establishment procedure, when an RRC reconfiguration sidelink message is sent to lower layers and the timer (e.g., a T400 timer) is started. According to some examples, the configuration 500 may include configuring the SL UE with an extension value corresponding to the above conditions, such as when a physical layer problem occurs, when a connection re-establishment is performed, when an exceptional resource pool is used, etc. In one example, the timer extension may relate to a timer configured to monitor a physical layer recovery procedure or a connection re-establishment procedure. For example, if the SL UE is configured with a constant T0 for the T400 timer and corresponding constants T1, T2, and T3 for detecting expiration of the T301, T310, and T311 timers, the SL UE may extend the T400 constant as (T0 + T2) when it detects a physical layer problem that triggers the start of T310. If the physical layer problem cannot be resolved and T310 expires, the SL UE may initiate a Uu connection re-establishment procedure, which includes selecting a suitable cell and another procedure to request RRC re-establishment over the Uu interface. In this case, the T400 timer constant may be extended as (T0+T2+T3+T1). In one example embodiment, the method includes configuring the SL UE to initiate the Uu connection re-establishment procedure upon another trigger (e.g., RLC failure due to reaching the maximum number of retransmissions). In this case, the T400 timer constant may be extended as (T0+T3+T1).

[0065] 5b illustrates an example flow diagram of a method for monitoring PC5-RRC configuration procedures, e.g., in NR SL mode 1, according to an example embodiment. In certain example embodiments, the flow diagram of FIG. 5b may be performed by a network entity or network node of a communications system, such as LTE or 5G NR. For example, in some example embodiments, the network entity performing the method of FIG. 5b may include a UE, such as an SL UE (e.g., an SL TX UE or an SL RX UE), a mobile station, an IoT device, or the like.

[0066] In one embodiment, the method of FIG. 5b may include determining at 530 whether there is a radio problem. For example, determining 530 may include determining whether there is a physical layer problem or a connection re-establishment or handover procedure over an interface between the SL UE and the network (e.g., a Uu interface). In one embodiment, if determining at 530 that there is no radio problem (e.g., no physical layer problem, no connection re-establishment procedure over the Uu interface, and / or no handover procedure has been performed), the method may include formulating an RRC reconfiguration sidelink message at 535. The method may include sending at 540 an RRC reconfiguration sidelink message to lower layers and starting a timer (e.g., timer T400) used to monitor the PC5 RRC (re)configuration procedure. For example, in one embodiment, sending 540 may include the RRC layer of the SL UE sending the RRC reconfiguration sidelink message to lower layers only if there is no physical layer problem or a connection re-establishment or handover procedure over the Uu interface. Otherwise, when it is determined at 530 that there is a radio problem (e.g. a physical layer problem, a connection re-establishment procedure over the Uu interface or a handover procedure), the method may include not constructing an RRC reconfiguration sidelink message at 550 and not starting a timer (e.g. timer T400) used to monitor the PC5RRC (re)configuration procedure.

[0067] 5c illustrates an example flow diagram of a method for monitoring a PC5-RRC configuration procedure, e.g., in NR SL mode 1, according to another example embodiment. In certain example embodiments, the flow diagram of FIG. 5c may be performed by a network entity or network node of a communications system, such as LTE or 5G NR. For example, in some example embodiments, the network entity performing the method of FIG. 5c may include a UE, such as an SL UE (e.g., an SL TX UE or an SL RX UE), a mobile station, an IoT device, or the like.

[0068] In one embodiment, the method of FIG. 5c may include, at 560, formulating an RRC reconfiguration sidelink message, sending it to lower layers, and starting a timer (e.g., timer T400) used to monitor the PC5 RRC (re)configuration procedure. According to one embodiment, after formulating the RRC reconfiguration sidelink message, sending it to lower layers, and starting the timer, the method may include, at 570, detecting that there is a radio problem (e.g., a physical layer problem, a connection re-establishment procedure over the Uu interface, or a handover procedure to a new cell over an interface (e.g., the Uu interface). In one embodiment, the method may include, at 580, maintaining the value of the timer (e.g., T400) until the radio problem is resolved. For example, the physical layer problem may be resolved and the radio problem may be resolved upon completion of a connection re-establishment procedure within the same serving cell or a handover procedure to a new cell over an interface (e.g., the Uu interface).

[0069] Thus, in one embodiment shown in the example of Figure 5c, if a physical layer problem is detected or a connection re-establishment procedure is initiated after constructing an RRC reconfiguration sidelink message and starting the T400 timer, the method may include holding the value of timer T400 until the physical layer problem is resolved, the connection re-establishment or handover procedure is completed, or the UE enters RRC idle mode.

[0070] In one embodiment, detecting 570 may include checking whether the T310 timer is running, which indicates that the SL UE has detected consecutive N310 out-of-sync indications from lower layers on the Uu interface.

[0071] For example, if a physical layer problem is detected (e.g., timer T310 starts or radio channel conditions are worse than a configured threshold), the method may include suspending timer T400 (i.e., the T400 timer is stopped but the value is not reset to an initial value). If the physical layer problem is resolved in the same serving cell (e.g., T310 stops or radio channel conditions are better than a configured threshold), the method may include restarting the T400 timer.

[0072] In one embodiment, when a connection re-establishment procedure is initiated (e.g., due to an RLC failure due to the maximum number of retransmissions over the Uu interface being reached, or due to a handover failure) or when a handover procedure is initiated, the method may include suspending timer T400. If Uu re-establishment is successful with the same serving cell, T400 may continue to run. If connection re-establishment or handover is successful with a new serving cell, or if connection re-establishment is not successful and the UE enters RRC idle mode, the method may include checking whether the PC5 configuration (if Uu re-establishment is successful) or SIB / pre-configuration (if idle mode was entered) obtained from the new serving cell complies with the configuration in the constructed RRC reconfiguration sidelink message. If so, the method may include restarting timer T400. When entering idle mode and switching to SL mode 2, a possible method is to start the T400 timer and use SL mode 2 once sensing results are available in the SL UE. If not, the method may include constructing a new RRC reconfiguration sidelink message accordingly and restarting timer T400 (i.e., the value of T400 is reset to 0 and T400 is started again) once sensing results for using SL mode 2 are available. For example, in this case the method may include constructing a new RRC reconfiguration sidelink message and restarting timer T400 upon transmission of the new RRC reconfiguration sidelink message.

[0073] In one example, if the connection re-establishment procedure or handover procedure fails, the method may include switching to SL mode 2 (i.e., UE autonomous resource selection mode). In this case, the method may include checking whether the configuration obtained from the SIB / preconfiguration complies with the configuration of the constructed RRC Reconfiguration sidelink message. If so, the method may include starting timer T400 when sensing results for using SL mode 2 are available. If not, the method may include constructing a new RRC Reconfiguration sidelink message accordingly when sensing results for using SL mode 2 are available. The method may also include restarting timer T400 when a new RRC Reconfiguration sidelink message is sent to lower layers.

[0074] In certain embodiments, the SL UE may be configured by the network with multiple values ​​for a timer (e.g., the T400 timer) or multiple different similar timers associated with the same PC5-RRC procedure. According to some examples, in the case of a physical layer problem or a connection re-establishment or handover procedure over the (Uu) interface, different values ​​or timers may be used or configured depending on different conditions experienced from the interface between the SL UE and the network (e.g., the Uu interface). For example, one value or timer may be used when no physical layer problem is detected and connection re-establishment and handover are not initiated. Another value or timer may be configured to be used, for example, when a physical layer problem is detected. In this case, when such a physical layer problem is detected, the RRC layer may update the value used to detect timer expiration (e.g., the T400 timer). Another value or timer may be configured to be used, for example, when connection re-establishment is initiated. For example, a different value or timer may be configured to be used when a handover procedure is initiated. Also, another value or timer may be configured to be used when the SL UE sends an RRC reconfiguration sidelink message using an exceptional resource pool. According to an example embodiment, multiple values ​​for T400 or multiple different T400-like timers may be applied if a Uu radio problem is detected before or after sending an RRCReconfigurationSidelink message to lower layers. Thus, in certain embodiments, different values ​​or timers used to monitor the PC5RRC (re)configuration procedure may be set / updated according to different radio conditions on the Uu interface.

[0075] In one example, the SL UE may be configured by the network to extend a timer (e.g., a T400 timer) upon detection of a physical layer problem or initiation of a connection re-establishment or handover procedure when an RRC Reconfiguration Sidelink message is sent to lower layers and the timer (e.g., a T400 timer) is started. According to some examples, the SL UE may be configured with an extension value corresponding to the above conditions, such as when a physical layer problem occurs, when a connection re-establishment or handover procedure is performed, when an exceptional resource pool is used, etc. In one example, the timer extension may relate to a timer configured to monitor a physical layer recovery procedure or a connection re-establishment or handover procedure.

[0076] It should be noted that one or more procedures, functions, or blocks shown in Figures 1, 2, 3, 4, 5a, 5b, or 5c may be optional or omitted according to a particular embodiment. Thus, while Figures 1, 2, 3, 4, 5a, or 5b show some examples, the examples should not be considered limited to only these examples. Furthermore, in certain embodiments, the examples illustrated in the flow diagrams of Figures 5a, 5b, or 5c may be combined or integrated.

[0077] 6a illustrates an example of a device 10 according to one embodiment. In one embodiment, the device 10 may be a node, a host, a server in a communications network, or one providing a service to such a network. For example, the device 10 may be a satellite, a base station, a Node B, an evolved Node B (eNB), a 5G Node B or access point, a next generation Node B (NG-NB or gNB), and / or a WLAN access point, and may be associated with a radio access network, such as an LTE network, 5G, or NR. In an example, the device 10 may be an NG-RAN node, an eNB in ​​LTE, or a gNB in ​​5G.

[0078] In some example embodiments, device 10 is configured with an edge cloud server as a distributed computing system, and it should be understood that the server and wireless node may be standalone devices that communicate with each other via wireless paths or wired connections, or may be located in the same entity that communicates via wired connections. For example, in a particular example embodiment in which device 10 represents a gNB, it may be configured with a central unit (CU) and distributed unit (DU) architecture that divides gNB functions. In such an architecture, the CU may be a logical node that includes gNB functions such as user data forwarding, mobility control, radio access network sharing, positioning, and / or session management, and the CU may control the operation of the DU via a fronthaul interface. The DU may be a logical node that includes a subset of gNB functions, depending on the function division option. It should be noted that those skilled in the art will understand that device 10 may include components or features not shown in FIG. 6a.

[0079] As shown in the example of FIG. 6a, device 10 may include processor 12 for processing information and executing instructions or operations. Processor 12 may be any type of general-purpose processor or special-purpose processor. Indeed, processor 12 may include, by way of example, one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), and a processor based on a multi-core processor architecture. While a single processor 12 is shown in FIG. 6a, multiple processors may be utilized in accordance with other embodiments. For example, it should be understood that in certain embodiments, device 10 may include multiple processors capable of forming a multiprocessor system (e.g., in which case processor 12 may represent multiple processors) and supporting multiprocessing. In certain embodiments, the multiprocessor system may be tightly coupled or loosely coupled (e.g., to form a computer cluster).

[0080] Processor 12 may perform functions related to the operation of device 10, including the overall control of device 10, including, for example, processes related to precoding antenna gain / phase parameters, encoding and decoding individual bits forming communication messages, formatting information, and managing communication resources.

[0081] Device 10 may further include or be coupled to processor 12 (internal or external) memory 14 for storing information and instructions that may be executed by processor 12. Memory 14 may be one or more memories of any type suitable for the local application environment and may be implemented using any suitable volatile or non-volatile data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and / or removable memory. For example, memory 14 may be configured with any combination of random access memory (RAM), read-only memory (ROM), static storage such as magnetic or optical disks, hard disk drives (HDDs), or any other type of non-transitory machine- or computer-readable media. The instructions stored in memory 14 may include program instructions or computer program code that, when executed by processor 12, enable device 10 to perform tasks such as those described herein.

[0082] In one embodiment, device 10 may further include or be coupled (internal or external) to a drive or port configured to accept and read an external computer-readable storage medium, such as an optical disk, a USB drive, a flash drive, or any other storage medium. For example, the external computer-readable storage medium may store computer programs or software executed by processor 12 and / or device 10.

[0083] In some embodiments, device 10 may also include or be coupled to one or more antennas 15 for transmitting and receiving signals and / or data to and from device 10. Device 10 may further include or be coupled to a transceiver 18 configured to transmit and receive information. Transceiver 18 may include, for example, multiple wireless interfaces that may be coupled to antennas 15. The wireless interfaces may support multiple wireless access technologies, including one or more of GSM, NB-IoT, LTE, 5G, WLAN, Bluetooth, BT-LE, NFC, radio frequency identification (RFID), ultra-wideband (UWB), MulteFire, etc. The wireless interfaces may include components such as filters, converters (e.g., digital-to-analog converters), mappers, fast Fourier transform (FFT) modules, etc., to generate symbols for transmission over one or more downlinks and receive symbols (e.g., via an uplink).

[0084] As such, transceiver 18 may be configured to modulate information onto a carrier waveform for transmission by antenna 15, and to demodulate information received via antenna 15 for further processing by other elements of device 10. In other embodiments, transceiver 18 may transmit and receive signals or data directly. Additionally or alternatively, in some embodiments, device 10 may include input and / or output devices (I / O devices).

[0085] In one embodiment, memory 14 may store software modules that provide functionality when executed by processor 12. The modules may include, for example, an operating system that provides operating system functionality for device 10. Memory may also store one or more functional modules, such as applications or programs, to provide additional functionality for device 10. Components of device 10 may be implemented in hardware or as a suitable combination of hardware and software.

[0086] According to some embodiments, the processor 12 and memory 14 may be included in or form part of processing or control circuitry. Further, in some embodiments, the transceiver 18 may be included in or form part of transceiver circuitry.

[0087] As used herein, the term “circuitry” may refer to a hardware-only circuit implementation (e.g., analog circuitry or digital circuitry), a combination of hardware circuitry and software, a combination of analog and / or digital hardware circuitry and software / firmware, any portion of a hardware processor and software (e.g., device 10) that work together to perform various functions and encase the device, and / or a hardware circuit and / or processor, or portion thereof, that uses software for operation but may not be present if software is not required for operation. As a further example, as used herein, the term “circuitry” may also include simply a hardware circuit or processor (or processors), or a portion of a hardware circuit or processor, and its associated software and / or firmware implementation. The term circuitry may also include, for example, a baseband integrated circuit in a server, a cellular network node or device, or other computing or network device.

[0088] As mentioned above, in certain embodiments, device 10 may be a NW or RAN node, such as a base station, access point, Node B, eNB, gNB, WLAN access point, etc. For example, in some embodiments, device 10 may be configured to perform one or more of the processes illustrated in any of the flowcharts or signal diagrams described herein, such as those shown in FIG. 1, 5a, or 5b. According to one embodiment, device 10 may correspond to the network blocks shown in the example of FIG. 1. In some embodiments, device 10 may be configured to perform procedures related to monitoring and improving PC5-RRC (re)configuration procedures in NR SL, for example, as discussed herein.

[0089] According to a particular embodiment, the device 10 is controlled by the memory 14 and the processor 12 and is capable of configuring the SL UE with operations for processing and monitoring the PC5RRC procedures and associated timers taking into account the status / problems of the Uu link.

[0090] In some examples, apparatus 10 may be controlled by memory 14 and processor 12 to configure the SL UE so that the RRC layer can construct and send an RRCReconfigurationSidelink message to lower layers when there are no radio problems (e.g., no physical layer problems detected, no connection re-establishment or handover procedure performed) over the Uu interface, and to prevent the SL UE from requesting SL resources from the network node. For example, in one embodiment, apparatus 10 may be controlled by memory 14 and processor 12 to configure the RRC layer of the SL UE to construct and send an RRCReconfigurationSidelink message to lower layers only when there are no physical layer problems or no connection re-establishment or handover procedure performed over the Uu interface. Otherwise, in one embodiment, apparatus 10 may be controlled by memory 14 and processor 12 to configure the SL UE so that its RRC layer does not send an RRCReconfigurationSidelink message to lower layers; thus, in this case, timer T400 is not started.

[0091] In another embodiment, the device 10 may be controlled by the memory 14 and the processor 12 to configure the SL UE to hold the value of timer T400 when the SL UE detects a Uu physical layer problem or initiates a Uu connection re-establishment or handover procedure after constructing an RRCReconfigurationSidelink message and starting timer T400, until the Uu physical layer problem is resolved, the Uu connection re-establishment or handover procedure is completed, or the SL UE enters RRC idle mode. For example, when the SL UE detects a physical layer problem (e.g., timer T310 starts or radio channel conditions are worse than a configured threshold), the device 10 may be controlled by the memory 14 and the processor 12 to configure the SL UE to suspend timer T400 (i.e., T400 is stopped but not reset to its initial value). When the Uu physical layer problem is resolved in the same serving cell (e.g., T310 stops or radio channel conditions are better than a configured threshold), the SL UE is configured to restart timer T400 so that it can continue running.

[0092] In one embodiment, the device 10, controlled by the memory 14 and the processor 12, can configure the SL UE to handle a timer (e.g., a T400 timer) used to determine when to perform an SL reconfiguration failure procedure. In one embodiment, the device 10, controlled by the memory 14 and the processor 12, can configure the SL UE to handle multiple values ​​of a timer (e.g., T400) or multiple different similar timers associated with the same PC5-RRC procedure. According to some examples, in the case of a physical layer problem or a connection re-establishment procedure over the (Uu) interface, different values ​​or timers may be used depending on the conditions experienced from the interface between the SL UE and the network (e.g., the Uu interface). For example, one value or timer may be used when no physical layer problem is detected and no connection re-establishment is initiated. Another value or timer may be configured to be used when a physical layer problem is detected. In this case, when such a physical layer problem is detected, the RRC layer may update a constant used to detect timer expiration (e.g., the T400 timer). Another value or timer may be configured to be used when a connection re-establishment is initiated. For example, a different value or timer can be configured to be used when an SL UE sends an RRC Reconfiguration sidelink message using an exceptional resource pool.

[0093] In one embodiment, the device 10 can be controlled by the memory 14 and the processor 12 to configure the SL UE to extend a timer (e.g., the T400 timer) upon detection of a physical layer problem or initiation of a connection re-establishment procedure when an RRC reconfiguration sidelink message is sent to lower layers and the timer (e.g., the T400 timer) is started. According to some examples, the device 10 can be controlled by the memory 14 and the processor 12 to configure the SL UE with an extension value corresponding to the above conditions, such as when a physical layer problem occurs, when a connection re-establishment is performed, when an exceptional resource pool is used, etc. In one example, the timer extension may relate to a timer configured to monitor a physical layer recovery procedure or a connection re-establishment procedure. For example, if the SL UE is configured with a constant T0 for the T400 timer and corresponding constants T1, T2, and T3 for detecting expiration of the T301, T310, and T311 timers, the T400 constant can be extended as (T0 + T2) when the SL UE detects a physical layer problem that triggers the start of T310. If the physical layer problem cannot be resolved and T310 expires, the SL UE may initiate a Uu connection re-establishment procedure, which includes a procedure to select a suitable cell and another procedure to request RRC re-establishment over the Uu interface. In this case, the constant for the T400 timer may be extended as (T0+T2+T3+T1). In one example embodiment, the device 10 may be controlled by the memory 14 and the processor 12 to configure the SL UE to initiate the Uu connection re-establishment procedure upon another trigger (e.g., RLC failure due to reaching the maximum number of retransmissions). In this case, the constant for the T400 timer may be extended as (T0+T3+T1).

[0094] 6b illustrates an example of apparatus 20 according to another embodiment. In one embodiment, apparatus 20 may be a node or element in a communications network or associated with such a network, such as a UE, mobile equipment (ME), mobile station, mobile device, fixed device, IoT device, or other device. As described herein, a UE may also be referred to as, for example, a mobile station, mobile equipment, mobile unit, mobile device, user device, subscriber station, wireless terminal, tablet, smartphone, IoT device, sensor, or NB-IoT device. By way of example, apparatus 20 may be implemented in, for example, a wireless handheld device, a wireless plug-in accessory, or the like.

[0095] In some example embodiments, device 20 may include one or more processors, one or more computer-readable storage media (e.g., memory, storage, etc.), one or more wireless access components (e.g., modems, transceivers, etc.), and / or a user interface. In some embodiments, device 20 may be configured to operate using one or more wireless access technologies, such as GSM, LTE, LTE-A, NR, 5G, WLAN, WiFi, NB-IoT, Bluetooth, NFC, MultiFire, and / or other wireless access technologies. It should be noted that one skilled in the art would understand that device 20 may include components or features not shown in FIG. 6b.

[0096] As shown in the example of FIG. 6b, device 20 may include or be coupled to a processor 22 for processing information and executing instructions or operations. Processor 22 may be any type of general-purpose or special-purpose processor. Indeed, processor 22 may include, by way of example, one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), and a processor based on a multi-core processor architecture. While a single processor 22 is shown in FIG. 6b, multiple processors may be utilized in accordance with other embodiments. For example, it should be understood that in certain embodiments, device 20 may include multiple processors capable of supporting multiprocessing, forming a multiprocessor system (e.g., in which case processor 22 may represent multiple processors). In certain embodiments, the multiprocessor system may be tightly coupled or loosely coupled (e.g., to form a computer cluster).

[0097] Processor 22 may perform functions related to the operation of device 20, including overall control of device 20, including processes related to precoding antenna gain / phase parameters, encoding and decoding individual bits that form communication messages, formatting information, and managing communication resources, as some examples.

[0098] Device 20 may further include or be coupled to processor 22 (internal or external) memory 24 for storing information and instructions that may be executed by processor 22. Memory 24 may be one or more memories of any type suitable for the local application environment and may be implemented using any suitable volatile or non-volatile data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and / or removable memory. For example, memory 24 may be comprised of any combination of random access memory (RAM), read-only memory (ROM), static storage such as magnetic or optical disks, hard disk drives (HDDs), or any other type of non-transitory machine- or computer-readable media. The instructions stored in memory 24 may include program instructions or computer program code that, when executed by processor 22, enable device 20 to perform tasks such as those described herein.

[0099] In one embodiment, device 20 may further include or be coupled (internal or external) to a drive or port configured to accept and read an external computer-readable storage medium, such as an optical disk, a USB drive, a flash drive, or any other storage medium. For example, the external computer-readable storage medium may store computer programs or software executed by processor 22 and / or device 20.

[0100] In some embodiments, device 20 may include or be coupled to one or more antennas 25 for receiving downlink signals and transmitting from device 20 via an uplink. Device 20 may further include a transceiver 28 configured to transmit and receive information. Transceiver 28 may also include a wireless interface (e.g., a modem) coupled to antenna 25. The wireless interface may support multiple wireless access technologies, including one or more of GSM, LTE, LTE-A, 5G, NR, WLAN, NB-IoT, Bluetooth, BT-LE, NFC, RFID, UWB, etc. The wireless interface may include other components, such as filters, converters (e.g., digital-to-analog converters), symbol demappers, signal shaping components, inverse fast Fourier transform (IFFT) modules, etc., to process symbols, such as OFDMA symbols, carried by the downlink or uplink.

[0101] For example, transceiver 28 may be configured to modulate information onto a carrier waveform for transmission by antenna 25 and demodulate information received via antenna 25 for further processing by other elements of device 20. In other embodiments, transceiver 28 may directly transmit and receive signals or data. Additionally or alternatively, in some embodiments, device 20 may include input and / or output devices (I / O devices). In particular embodiments, device 20 may further include a user interface, such as a graphical user interface or a touch screen.

[0102] In one embodiment, memory 24 stores software modules that provide functionality when executed by processor 22. The modules may include, for example, an operating system that provides operating system functionality for device 20. The memory may also store one or more functional modules, such as applications or programs, to provide additional functionality for device 20. Components of device 20 may be implemented in hardware or as a suitable combination of hardware and software. According to one example embodiment, device 20 may be optionally configured to communicate with device 10 or device 30 via a wireless or wired communication link or interface 70 according to any wireless access technology, such as NR.

[0103] According to some embodiments, the processor 22 and memory 24 may be included in or form part of processing or control circuitry. Further, in some embodiments, the transceiver 28 may be included in or form part of transmitting and receiving circuitry.

[0104] As mentioned above, according to some embodiments, apparatus 20 may be, for example, a UE (e.g., SL UE), a mobile device, a mobile station, a ME, an IoT device, and / or an NB-IoT device. According to particular embodiments, apparatus 20 may be controlled by memory 24 and processor 22 to perform functions associated with example embodiments described herein. For example, in some embodiments, apparatus 20 may be configured to perform one or more of the processes illustrated in any of the flowcharts or signal diagrams described herein, such as those shown in FIGS. 1-4, 5a, or 5b. In particular embodiments, apparatus 20 may include or be equivalent to a UE, such as an SL UE. In one example embodiment, apparatus 20 may represent an SL TX UE, such as that shown in the example of FIG. 1. According to one embodiment, apparatus 20 may be configured to perform procedures related to monitoring and improving PC5-RRC (re)configuration procedures, for example, in NR SL.

[0105] In certain embodiments, the device 20 may be controlled by the memory 24 and the processor 22 to determine whether there is a radio problem. For example, the radio problem may include a physical layer problem or a connection re-establishment or handover procedure over an interface between the SL UE and the network (e.g., the Uu interface). In one embodiment, if it is determined that there is no radio problem (e.g., no physical layer problem, no connection re-establishment procedure over the Uu interface, and / or no handover procedure has been performed), the device 20 may be controlled by the memory 24 and the processor 22 to configure an RRC Reconfiguration sidelink message. According to certain embodiments, the device 20 may be controlled by the memory 24 and the processor 22 to send the RRC Reconfiguration sidelink message to lower layers and to start a timer used to monitor the PC5 RRC (re)configuration procedure (e.g., timer T400). For example, in one embodiment, the RRC layer of the device 20 may be controlled to send the RRC Reconfiguration sidelink message to lower layers only if there is no physical layer problem or no connection re-establishment or handover procedure over the Uu interface. Otherwise, when it is determined that there is a radio problem (e.g., a physical layer problem, a connection re-establishment procedure or a handover procedure over the Uu interface), the device 20, controlled by the memory 24 and the processor 22, does not start a timer (e.g., timer T400) used to monitor the PC5 RRC (re)configuration procedure. In some embodiments, if an RRC reconfiguration sidelink message is transmitted and timer T400 is started, the device 20, controlled by the memory 24 and the processor 22, may retain the value of the timer (e.g., T400) upon detecting a physical layer problem or a connection re-establishment procedure or a handover procedure over the interface (e.g., the Uu interface).

[0106] For example, in one embodiment, to determine whether there is a physical layer problem, the device 20 can be controlled by the memory 24 and the processor 22 to check whether the T310 timer is running, which indicates that the device 20 has detected a continuous N310 out-of-sync indication from lower layers on the Uu interface. Therefore, if the T400 timer is started without noticing that the T310 timer is running, the T400 timer may expire and the PC5 link may be released before the physical layer problem is resolved, which is undesirable because it does not reflect the status of the PC5 link. In this example, if it is determined that there is a physical layer problem, e.g., if the T310 timer is stopped, the device 20 can be controlled by the memory 24 and the processor 22 to configure an RRC reconfiguration sidelink message after the physical layer problem is resolved.

[0107] The same method also applies when the device 20 is about to perform a Uu connection re-establishment procedure, for example, when timer T301 or T311 is running. In this case, if it is determined that a connection re-establishment procedure via an interface (e.g., the Uu interface) is occurring, the device 20 will be unable to obtain SL resources from the network before the Uu connection is re-established. Therefore, since the PC5 link is released when T400 expires, it is necessary not to start T400 in this case to avoid T400 expiring before the Uu connection establishment is complete. Furthermore, when the UE re-establishes a Uu connection to a new cell, it may acquire new PC5 settings from the new cell. Therefore, if it is determined that a connection re-establishment procedure via an interface (e.g., the Uu interface) is occurring, the device 20 may be controlled by the memory 24 and the processor 22 to construct an RRC reconfiguration sidelink message after the connection re-establishment.

[0108] In another example, upon receiving an RRCReconfiguration message containing reconfigurationWithSync, the device 20, under the control of the memory 24 and the processor 22, starts a timer T304 and performs a handover to the corresponding special cell (SpCell). As a result, the device 20 cannot request sidelink resources from the network before the handover procedure is successful. Again, it is reasonable for the device 20 to wait and construct an RRCReconfigurationSidelink message after the handover procedure, since the device 20 can obtain a new PC5 setting from the target cell.

[0109] In one embodiment, the device 20 may be controlled by the memory 24 and the processor 22 to formulate and transmit the RRC reconfiguration sidelink message and to start a timer (e.g., timer T400) used to monitor the PC5 RRC (re)configuration procedure. According to one embodiment, after constructing and transmitting the RRC reconfiguration sidelink message and starting the timer, the device 20 may be controlled by the memory 24 and the processor 22 to detect that there is a radio problem (e.g. a physical layer problem, a connection re-establishment procedure over the Uu interface or a handover procedure). In one embodiment, the device 20 is controlled by the memory 24 and the processor 22 to maintain the value of the timer (e.g. T400) until the radio problem is resolved.

[0110] Thus, in one embodiment, if a physical layer problem is detected or a connection re-establishment procedure is initiated after constructing the RRC reconfiguration sidelink message and starting the T400 timer, the device 20 may be controlled by the memory 24 and the processor 22 to hold the value of the timer T400 until the physical layer problem is resolved, the connection re-establishment is completed, the handover procedure is completed, or the device 20 enters an RRC idle mode. For example, if a physical layer problem is detected (e.g., the timer T310 is started or the radio channel conditions are worse than a configured threshold), the device 20 may be controlled by the memory 24 and the processor 22 to put the timer T400 in a pending state (i.e., the T400 timer is stopped but the value is not reset to 0). If the physical layer problem is resolved in the same serving cell (e.g., the T310 is stopped or the radio channel conditions are better than a configured threshold), the device 20 may be controlled by the memory 24 and the processor 22 to start the T400 timer again.

[0111] In one embodiment, when a connection re-establishment procedure is initiated (e.g., due to an RLC failure due to the maximum number of retransmissions over the Uu interface being reached, or due to a handover failure), or when a handover procedure is initiated, the device 20, under the control of the memory 24 and the processor 22, can suspend timer T400. If the Uu re-establishment is successful with the same serving cell, the device 20, under the control of the memory 24 and the processor 22, can continue to run timer T400. If the connection re-establishment or handover is successful with the new serving cell, or if the connection re-establishment is not successful and the UE enters RRC idle mode, the device 20, under the control of the memory 24 and the processor 22, can check whether the PC5 configuration (if the Uu re-establishment is successful) or SIB / preconfiguration (if the UE enters idle mode) obtained from the new serving cell conforms to the configuration of the constructed RRC reconfiguration sidelink message. If so, the device 20, under the control of the memory 24 and the processor 22, can start timer T400 again. In the case of entering idle mode and switching to SL mode 2, once sensing results are available in device 20 for using SL mode 2, device 20, controlled by memory 24 and processor 22, may start timer T400. In the case of non-compliance, once sensing results for using SL mode 2 are available, device 20, controlled by memory 24 and processor 22, may construct a new RRC Reconfiguration sidelink message accordingly and restart timer T400 (i.e., the value of T400 is reset to 0 and T400 is started again). For example, in this case, device 20, controlled by memory 24 and processor 22, may construct a new RRC Reconfiguration sidelink message and restart timer T400 upon transmission of the new RRC Reconfiguration sidelink message.

[0112] In one example, if the connection re-establishment or handover procedure fails, the device 20 may be controlled by the memory 24 and the processor 22 to switch to SL mode 2 (i.e., UE autonomous resource selection mode). In this case, the device 20 may be controlled by the memory 24 and the processor 22 to check whether the configuration obtained from the SIB / preconfiguration complies with the configuration of the constructed RRC Reconfiguration sidelink message. If so, the device 20 may be controlled by the memory 24 and the processor 22 to start timer T400 when a sensing result is available for using SL mode 2. If not, the device 20 may be controlled by the memory 24 and the processor 22 to construct a new RRC Reconfiguration sidelink message accordingly when a sensing result is available for using SL mode 2. The device 20 may also be controlled by the memory 24 and the processor 22 to restart timer T400 when a new RRC Reconfiguration sidelink message is transmitted to lower layers.

[0113] In certain embodiments, the device 20 may be configured by the network with multiple timer values ​​(e.g., T400 timer) or multiple different similar timers associated with the same PC5-RRC procedure. According to some examples, in the event of a physical layer problem or a connection re-establishment or handover procedure over the (Uu) interface, different values ​​or timers may be used or configured according to different conditions experienced from the interface between the device 20 and the network (e.g., Uu interface). For example, one value or timer may be used when no physical layer problem is detected and no connection re-establishment or handover procedure is initiated. Another value or timer may be configured to be used when, for example, a physical layer problem is detected. In this case, when such a physical layer problem is detected, the RRC layer may update a constant used to detect timer expiration (e.g., T400 timer). Another value or timer may be configured to be used when, for example, a connection re-establishment is initiated. For example, a different value or timer may be configured to be used when a handover procedure is initiated. Also, another value or timer may be configured to be used when, for example, the device 20 transmits an RRC reconfiguration sidelink message using an exceptional resource pool.

[0114] In one embodiment, the device 20 may be configured by the network to extend a timer (e.g., T400 timer) upon detection of a physical layer problem or initiation of a connection re-establishment procedure when an RRC reconfiguration sidelink message is sent to lower layers and the timer (e.g., T400 timer) is started. According to some examples, the device 20 may be configured with an extension value corresponding to the above conditions, such as encountering a physical layer problem, performing a connection re-establishment, using an exceptional resource pool, etc. In one example, the timer extension may relate to a timer configured to monitor a physical layer recovery procedure or a connection re-establishment procedure.

[0115] 6c illustrates an example of apparatus 30 according to another embodiment. In one example embodiment, apparatus 30 may be a node or element in a communications network or associated with such a network, such as a UE, mobile equipment (ME), mobile station, mobile device, fixed device, IoT device, or other device. As described herein, a UE may also be referred to as, for example, a mobile station, mobile equipment, mobile unit, mobile device, user device, subscriber station, wireless terminal, tablet, smartphone, IoT device or NB-IoT device, connected car, etc. By way of example, apparatus 30 may be implemented in, for example, a wireless handheld device, a wireless plug-in accessory, etc.

[0116] In some example embodiments, device 30 may include one or more processors, one or more computer-readable storage media (e.g., memory, storage, etc.), one or more wireless access components (e.g., modems, transceivers, etc.), and / or a user interface. In some example embodiments, device 30 may be configured to operate using one or more wireless access technologies, such as GSM, LTE, LTE-A, NR, 5G, WLAN, WiFi, NB-IoT, MulteFire, and / or any other wireless access technology. It should be noted that one skilled in the art would understand that device 30 may include components or features not shown in FIG. 6c.

[0117] As shown in the example of FIG. 6c, device 30 may include or be coupled to a processor 32 for processing information and executing instructions or operations. Processor 32 may be any type of general-purpose or special-purpose processor. Indeed, processor 32 may include, by way of example, one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), and a processor based on a multi-core processor architecture. While a single processor 32 is shown in FIG. 6c, multiple processors may be utilized according to other embodiments. For example, it should be understood that in certain example embodiments, device 30 may include multiple processors that may form a multiprocessor system (e.g., in this case, processor 32 may represent multiple processors) and support multiprocessing. In certain example embodiments, the multiprocessor system may be tightly coupled or loosely coupled (e.g., to form a computer cluster).

[0118] The processor 32 may perform functions related to the operation of the device 30, including the overall control of the device 30, including processes related to precoding antenna gain / phase parameters, encoding and decoding individual bits that form communication messages, formatting information, and managing communication resources, as some examples.

[0119] Device 30 may further include or be coupled to processor 32 (internal or external) memory 34 for storing information and instructions that may be executed by processor 32. Memory 34 may be one or more memories of any type suitable for the local application environment and may be implemented using any suitable volatile or non-volatile data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and / or removable memory. For example, memory 34 may be comprised of any combination of random access memory (RAM), read-only memory (ROM), static storage such as magnetic or optical disks, hard disk drives (HDDs), or any other type of non-transitory machine- or computer-readable media. The instructions stored in memory 34 may include program instructions or computer program code that, when executed by processor 32, enable device 30 to perform tasks such as those described herein.

[0120] In one example embodiment, device 30 may further include or be coupled to (internal or external) a drive or port configured to accept and read an external computer-readable storage medium, such as an optical disk, a USB drive, a flash drive, or any other storage medium. For example, the external computer-readable storage medium may store computer programs or software executed by processor 32 and / or device 30.

[0121] In some example embodiments, device 30 may include or be coupled to one or more antennas 35 for receiving downlink signals and transmitting them from device 30 via an uplink. Device 30 may further include a transceiver 38 configured to transmit and receive information. Transceiver 38 may also include a radio interface (e.g., a modem) coupled to antenna 35. The radio interface may support multiple radio access technologies, including one or more of GSM, LTE, LTE-A, 5G, NR, WLAN, NB-IoT, BT-LE, RFID, UWB, etc. The radio interface may include other components, such as filters, converters (e.g., digital-to-analog converters, etc.), symbol demappers, signal shaping components, inverse fast Fourier transform (IFFT) modules, etc., to process symbols, such as OFDMA symbols, carried by the downlink or uplink.

[0122] For example, transceiver 38 may be configured to modulate information onto a carrier waveform for transmission by antenna 35 and demodulate information received via antenna 35 for further processing by other elements of device 30. In other example embodiments, transceiver 38 may directly transmit and receive signals or data. Additionally or alternatively, in some example embodiments, device 30 may include input and / or output devices (I / O devices). In certain example embodiments, device 30 may further include a user interface, such as a graphical user interface or a touch screen.

[0123] In one example embodiment, memory 34 stores software modules that provide functionality when executed by processor 32. The modules may include, for example, an operating system that provides operating system functionality for device 30. The memory may also store one or more functional modules, such as applications or programs, to provide additional functionality for device 30. The components of device 30 may be implemented in hardware or as a suitable combination of hardware and software. According to an example embodiment, device 30 may be optionally configured to communicate with device 10 via wireless or wired communication link 71 and / or with device 20 via wireless or wired communication link 72 according to any wireless access technology, such as NR.

[0124] According to some example embodiments, the processor 32 and memory 34 may be included in or form part of processing or control circuitry. Further, in some example embodiments, the transceiver 38 may be included in or form part of transmitting and receiving circuitry.

[0125] As mentioned above, according to some example embodiments, apparatus 30 may be, for example, a UE (e.g., SL UE), a mobile device, a mobile station, an ME, an IoT device, and / or an NB-IoT device. According to certain example embodiments, apparatus 30 may be controlled by memory 34 and processor 32 to perform functions related to example embodiments described herein. For example, in some example embodiments, apparatus 30 may be configured to perform one or more of the processes illustrated in any of the figures or signal flow diagrams described herein. By way of example, apparatus 30 may correspond to or represent a UE, such as one or more UEs illustrated in FIG. 1, e.g., SL RX UEs. According to certain example embodiments, apparatus 30 may be configured to perform procedures related to monitoring and improving PC5-RRC (re)configuration procedures in NR SL.

[0126] In some embodiments, the device 30 may be controlled by the memory 34 and the processor 32 to receive an RRC reconfiguration sidelink message from an SL UE (e.g., an SL TX UE or device 20) and to send an RRC reconfiguration complete sidelink message to the SL UE (e.g., an SL TX UE or device 20).

[0127] Accordingly, certain example embodiments provide several technical improvements, enhancements, and / or advantages over existing technical processes, constituting improvements at least in the field of wireless network control and management. For example, certain embodiments enable an SL UE to avoid a PC5-RRC radio link failure, such as due to a Uu radio link issue. As a result, according to an example embodiment, the SL UE can maintain V2X service because it can continue to connect and communicate with the PC5. Therefore, use of certain example embodiments improves the functionality of a communication network and its nodes (e.g., base stations, eNBs, gNBs, and / or UEs or mobile stations).

[0128] In some exemplary embodiments, the functions of any of the methods, processes, signaling diagrams, algorithms or flowcharts described herein may be implemented by software and / or computer program code, or portions of code stored in memory or other computer-readable or tangible medium, and executed by a processor.

[0129] In some example embodiments, the device is included in or associated with at least one software application, module, unit, or entity configured as an arithmetic operation executed by at least one computing processor, or as a program or part thereof (including added or updated software routines). A program, also called a program product or computer program, including software routines, applets, and macros, may be stored on any device-readable data storage medium and include program instructions for performing specific tasks.

[0130] The computer program product may include one or more computer-executable components configured to perform some exemplary embodiments when the program is executed. The one or more computer-executable components may be at least one software code or portion of code. The modifications and configurations required to implement the functionality of the exemplary embodiments may be performed as routines, which may be implemented as added or updated software routines. In one example, the software routines may be downloaded to a device.

[0131] By way of example, the software or computer program code or portions of code may be in source code form, object code form, or some intermediate form, and may be stored on some carrier, distribution medium, or computer-readable medium, which is any entity or device capable of carrying a program. Such carriers include, for example, recording media, computer memory, read-only memory, optical and / or electrical carrier signals, telecommunications signals, and / or software distribution packages. The computer program may be executed in one electronic digital computer or distributed among several computers, depending on the processing power required. The computer-readable medium or computer-readable storage medium may be a non-transitory medium.

[0132] In other example embodiments, the functions are performed by hardware or circuitry included in the device, for example, by using an application specific integrated circuit (ASIC), a programmable gate array (PGA), a field programmable gate array (FPGA), or any other combination of hardware and software. In yet another exemplary embodiment, the functions may be implemented as signals by non-tangible means, such as those that may be transmitted by electromagnetic signals downloaded from the internet or other network.

[0133] According to an example embodiment, an apparatus such as a node, device or corresponding component may be configured as a circuit, a microprocessor such as a computer or single-chip computer element, or may be configured as a chipset, which may include at least a memory providing storage capacity used for arithmetic operations and / or an arithmetic processor for performing arithmetic operations.

[0134] Those skilled in the art will readily appreciate that the exemplary embodiments described above may be implemented using steps in a different order and / or with hardware elements in different configurations than those disclosed. Thus, while several examples have been described based on these examples, it will be apparent to those skilled in the art that certain modifications, variations, and alternative configurations will be apparent while remaining within the spirit and scope of the examples.

Claims

1. 1. A method comprising: a network node receiving from a side link user equipment (SL) a request relating to determining that an interface between the SL user equipment (SL) and a network node has a radio problem, the network node sending a grant to the side link user equipment (SL) to configure the side link user equipment (SL) to process and monitor PC5-Radio Resource Control (RRC) procedures and one or more timers relating to the side link user equipment (SL)

2. 2. The method of claim 1, wherein the configuring step comprises configuring the sidelink (SL) user equipment (UE) to handle a timer used to monitor the PC5-RRC configuration or reconfiguration procedure.

3. wherein the configuring step comprises configuring the Sidelink (SL) User Equipment (UE) with multiple values ​​for the timer or multiple different timers associated with the same PC5-RRC procedure; 3. The method of claim 1, wherein the values ​​or timers are used depending on historical information of an interface between the side link (SL) user equipment (UE) and the network node if there is a physical layer problem or a connection re-establishment or handover procedure over the interface.

4. a value or timer is configured to be used when no physical layer problem is detected over the interface and no connection re-establishment or handover procedure is initiated; 4. The method of claim 3, wherein another value or timer is configured to be used in at least one of the following cases: when a physical layer problem is detected, when a connection re-establishment is initiated, when a handover procedure is initiated, or when the sidelink (SL) user equipment (UE) uses an exceptional resource pool for transmitting a radio resource control (RRC) reconfiguration sidelink message.

5. 5. The method of claim 2, wherein the configuring step comprises configuring the sidelink (SL) user equipment (UE) to extend the timer upon the detection of a physical layer problem or the initiation of the connection re-establishment procedure or the handover procedure if the Radio Resource Control (RRC) Reconfiguration sidelink message is sent to lower layers and the timer was started.

6. 6. The method according to claim 1, wherein the configuring step comprises configuring the sidelink (SL) user equipment (UE) with a value of the extension corresponding to at least one of the following conditions: occurrence of a physical layer problem, execution of a connection re-establishment procedure or a handover procedure, or use of an exceptional resource pool.

7. at least one processor; at least one memory containing computer program code, The at least one memory and computer program code, together with the at least one processor, cause the device to: receiving a request from a side link (SL) user equipment (UE) relating to determining that there is a radio problem with an interface between the SL user equipment (UE) and the device; 1. An apparatus for causing a side link (SL) user equipment (UE) to perform at least the step of configuring the side link (SL) user equipment (UE) to process and monitor PC5-Radio Resource Control (RRC) procedures and one or more associated timers by sending a grant to the side link (SL) user equipment (UE).

8. 8. The apparatus of claim 7, wherein the configuring step comprises configuring the sidelink (SL) user equipment (UE) to process a timer used to monitor the PC5-RRC configuration or reconfiguration procedure.

9. wherein the configuring step comprises configuring the Sidelink (SL) User Equipment (UE) with multiple values ​​for the timer or multiple different timers associated with the same PC5-RRC procedure; 9. The apparatus according to claim 7, wherein the plurality of values ​​or plurality of timers are used depending on historical information of an interface between the side link (SL) user equipment (UE) and the network node if there is a physical layer problem or a connection re-establishment procedure or a handover procedure over the interface.

10. a value or timer is configured to be used when no physical layer problem is detected over the interface and no connection re-establishment or handover procedure is initiated; 10. The apparatus of claim 9, wherein another value or timer is configured to be used in at least one of the following cases: when a physical layer problem is detected, when a connection re-establishment is initiated, when a handover procedure is initiated, or when the sidelink (SL) user equipment (UE) uses an exceptional resource pool for transmitting a radio resource control (RRC) reconfiguration sidelink message.

11. 11. The apparatus according to claim 8, wherein the configuring step comprises configuring the sidelink (SL) user equipment (UE) to extend the timer upon the detection of a physical layer problem or the initiation of the connection re-establishment procedure or the handover procedure if the Radio Resource Control (RRC) Reconfiguration sidelink message is sent to a lower layer and the timer has been started.

12. 12. The apparatus according to claim 7, wherein the configuring step comprises configuring the sidelink (SL) user equipment (UE) with a value of the extension corresponding to at least one of the following conditions: occurrence of a physical layer problem, execution of a connection re-establishment procedure or a handover procedure, or use of an exceptional resource pool.

13. 1. An apparatus comprising: means for receiving a request from a side link (SL) user equipment (UE) relating to determining that an interface between the SL user equipment (UE) and the device has a radio problem; 1. An apparatus comprising: means for transmitting a grant to a side link (SL) user equipment (UE) to configure the UE with operations for processing and monitoring PC5-Radio Resource Control (RRC) procedures and one or more associated timers.

14. 14. The apparatus of claim 13, wherein the means for configuring comprises means for configuring the sidelink (SL) user equipment (UE) for processing a timer used to monitor the PC5-RRC configuration or reconfiguration procedure.

15. the means for configuring comprises means for configuring the side link (SL) user equipment (UE) with multiple values ​​for the timer or multiple different timers associated with the same PC5-RRC procedure; 15. The apparatus according to claim 13 or 14, wherein the values ​​or timers are used depending on historical information of an interface between the side link (SL) user equipment (UE) and the network node if there is a physical layer problem or a connection re-establishment procedure or a handover procedure over the interface.

16. a value or timer is configured to be used when no physical layer problem is detected over the interface and no connection re-establishment or handover procedure is initiated; 16. The apparatus of claim 15, wherein another value or timer is configured to be used in at least one of the following cases: when a physical layer problem is detected, when a connection re-establishment is initiated, when a handover procedure is initiated, or when the sidelink (SL) user equipment (UE) uses an exceptional resource pool for transmitting a radio resource control (RRC) reconfiguration sidelink message.

17. 17. The apparatus according to claim 14, wherein the configuring means comprises means for configuring the sidelink (SL) user equipment (UE) to extend the timer upon the detection of a physical layer problem or the initiation of the connection re-establishment procedure or the handover procedure if the Radio Resource Control (RRC) Reconfiguration sidelink message is sent to a lower layer and the timer is started.

18. 18. The apparatus according to claim 13, wherein the means for configuring comprises means for configuring the sidelink (SL) user equipment (UE) with the extended value corresponding to at least one of the following conditions: occurrence of a physical layer problem, execution of a connection re-establishment procedure or a handover procedure, or use of an exceptional resource pool.

19. determining, in a sidelink (SL) user equipment (UE), whether there is a radio problem at the interface between the sidelink (SL) user equipment (UE) and a network node; generating or constructing a Radio Resource Control (RRC) reconfiguration sidelink message if it is determined that there are no radio problems on the interface; and if a radio problem occurs on the interface after generating or constructing the Radio Resource Control (RRC) reconfiguration sidelink message, sending a scheduling request to the network node and maintaining operation of processing and monitoring a PC5-Radio Resource Control (RRC) procedure and one or more associated timers; and resuming or resetting the held operation by receiving a grant from the network node.

20. determining whether there is a radio problem comprises determining whether there is a physical layer problem or a connection re-establishment or handover procedure over an interface between the side link (SL) user equipment (UE) and the network node; 20. The method of claim 19, wherein if it is determined that there is no physical layer problem or no connection re-establishment or handover procedure over the interface, the method comprises sending the Radio Resource Control (RRC) Reconfiguration sidelink message to lower layers and starting a timer.

21. The step of determining whether there is a wireless problem includes: Whether one or more exceptional resource pools are configured, or whether the sidelink (SL) user equipment (UE) received a resource of the configured grant type before the radio problem was detected; 21. The method of claim 19 or 20, comprising determining at least one of:

22. 22. The method according to claim 19, wherein the step of constructing the Radio Resource Configuration (RRC) reconfiguration sidelink message is performed in the Radio Resource Control (RRC) layer of the sidelink (SL) user equipment (UE).

23. 23. The method of claim 20, wherein in the absence of a physical layer problem or a connection re-establishment or handover procedure, the sending comprises sending the Radio Resource Control (RRC) reconfiguration sidelink message to the lower layer via the Radio Resource Control (RRC) layer in the sidelink (SL) user equipment (UE).

24. If it is determined that there is a physical layer problem or a connection re-establishment or handover procedure over the interface, the method comprises: not generating or constructing the Radio Resource Control (RRC) reconfiguration sidelink message; and 24. The method of any one of claims 20 to 23, comprising the step of not starting the timer used to monitor the PC-5 Radio Resource Control (RRC) configuration procedure.

25. The determining step includes: physical layer recovery procedures, the connection re-establishment procedure, or The handover procedure 25. The method of any one of claims 19 to 24, comprising checking one or more timers set to monitor at least one of:

26. 26. The method of claim 19, wherein if it is determined that there is a connection re-establishment or handover procedure over the interface, the constructing step comprises constructing the Radio Resource Control (RRC) Reconfiguration sidelink message after the connection re-establishment or handover to a target cell.

27. at least one processor; at least one memory containing computer program code, The at least one memory and computer program code, together with the at least one processor, cause the device to: determining whether there is a radio problem at the interface between the device and a network node; generating or constructing a Radio Resource Control (RRC) reconfiguration sidelink message if it is determined that there are no radio problems on the interface; if a radio problem occurs on the interface after generating or constructing the Radio Resource Control (RRC) reconfiguration sidelink message, sending a scheduling request to the network node and maintaining operation of processing and monitoring a PC5-Radio Resource Control (RRC) procedure and one or more associated timers; and a step of resuming or resetting the held operation by receiving a grant from the network node.

28. determining whether there is a radio problem comprises determining whether there is a physical layer problem or a connection re-establishment or handover procedure over an interface between the side link (SL) user equipment (UE) and the network node; 28. The apparatus of claim 27, wherein the at least one memory and the computer program code, together with the at least one processor, cause the apparatus to perform at least the steps of: sending the Radio Resource Control (RRC) reconfiguration sidelink message to lower layers and starting a timer if it is determined that there is no physical layer problem or a connection re-establishment procedure or a handover procedure over the interface.

29. The step of determining whether there is a wireless problem includes: Whether one or more exceptional resource pools are configured, or Whether the device received a resource of the configured grant type before the wireless problem was detected 29. The apparatus of claim 27 or 28, comprising determining at least one of:

30. 30. The apparatus of claim 27, wherein the step of constructing the Radio Resource Control (RRC) reconfiguration sidelink message is performed in the Radio Resource Control (RRC) layer of the apparatus.

31. 31. The apparatus of claim 28, wherein in the absence of a physical layer problem or a connection re-establishment or handover procedure, the sending comprises sending the Radio Resource Control (RRC) reconfiguration sidelink message to the lower layer via the Radio Resource Control (RRC) layer in the apparatus.

32. If it is determined that there is a physical layer problem or a connection re-establishment or handover procedure over said interface, The at least one memory and computer program code, together with the at least one processor, cause the device to: skipping the generating or constructing the Radio Resource Control (RRC) Reconfiguration sidelink message; and The apparatus of any one of claims 28 to 31, further comprising at least the step of skipping the step of starting the timer used to monitor the PC-5 Radio Resource Control (RRC) configuration procedure.

33. The determining step includes: Physical layer recovery procedures, the connection re-establishment procedure, or The handover procedure 33. The apparatus of any one of claims 27 to 32, including checking one or more timers set to monitor at least one of:

34. 34. The apparatus of claim 27, wherein if it is determined that there is a connection re-establishment procedure or a handover procedure over the interface, the constructing step comprises constructing the Radio Resource Control (RRC) Reconfiguration sidelink message after the connection re-establishment or handover to a target cell.

35. means for determining the presence or absence of radio problems at the interface between the device and a network node; means for generating or constructing a Radio Resource Control (RRC) reconfiguration sidelink message if it is determined that there are no radio problems on the interface; 、 means for transmitting a scheduling request to the network node and for maintaining operation of processing and monitoring a PC5-Radio Resource Control (RRC) procedure and one or more associated timers if a radio problem occurs on the interface after generating or constructing the Radio Resource Control (RRC) reconfiguration sidelink message; and means for resuming or resetting the held operation by receiving a grant from the network node.

36. the means for determining the presence or absence of a radio problem comprises means for determining the presence or absence of a physical layer problem or a connection re-establishment or handover procedure over an interface between the side link (SL) user equipment (UE) and the network node; 36. The apparatus of claim 35, further comprising means for transmitting the Radio Resource Control (RRC) reconfiguration sidelink message to lower layers and starting a timer if it is determined that there is no physical layer problem or no connection re-establishment or handover procedure over the interface.

37. The means for determining whether there is a wireless problem includes: Whether one or more exceptional resource pools are configured, or Whether the device received a resource of the configured grant type before the wireless problem was detected 37. Apparatus according to claim 35 or 36, comprising means for determining at least one of:

38. 38. The apparatus of claim 35, wherein the means for constructing the Radio Resource Control (RRC) reconfiguration sidelink message is executed in the Radio Resource Control (RRC) layer of the apparatus.

39. 39. The apparatus of claim 36, wherein the means for transmitting comprises means for transmitting the Radio Resource Control (RRC) reconfiguration sidelink message to the lower layer via the Radio Resource Control (RRC) layer in the apparatus in the event of a physical layer problem or in the absence of a connection re-establishment procedure or a handover procedure.

40. means for the device to skip generating or constructing the Radio Resource Control (RRC) reconfiguration sidelink message if it is determined that there is a physical layer problem or a connection re-establishment or handover procedure over the interface; and 40. The apparatus of claim 36, further comprising: means for skipping the starting of the timer used to monitor the PC-5 Radio Resource Control (RRC) configuration procedure.

41. The determining means includes: Physical layer recovery procedures, the connection re-establishment procedure, or The handover procedure 41. Apparatus according to any one of claims 35 to 40, including means for checking one or more timers set to monitor at least one of:

42. 42. The apparatus of claim 35, wherein if it is determined that there is a connection re-establishment procedure or a handover procedure over the interface, the constructing means comprises means for constructing the Radio Resource Control (RRC) reconfiguration sidelink message after the connection re-establishment or handover to a target cell.

43. A method of claim 42, comprising: determining, in a side link (SL) user equipment (UE), whether there is a radio problem at an interface between the side link (SL) user equipment (UE) and a network node; generating or constructing, at the sidelink (SL) user equipment (UE), a radio resource control (RRC) reconfiguration sidelink message if it is determined that there are no radio problems on the interface; starting a timer used to monitor the PC5-Radio Resource Control (RRC) configuration procedure; if a radio problem occurs on the interface after starting the timer, sending a scheduling request to the network node and maintaining the timer; and receiving a grant from the network node thereby restarting or resetting the maintained timer.

44. detecting that there is a radio problem of the interface between the Side Link (SL) User Equipment (UE) and a network node; and 44. The method of claim 43, including holding the value of the timer until the radio problem for the interface is resolved.

45. 45. The method of claim 44, wherein the step of detecting that there is a radio problem on the interface comprises detecting a physical layer problem or the initiation of a connection re-establishment or handover procedure over a Uu interface.

46. If a physical layer problem is detected or if a connection re-establishment procedure or a handover procedure is initiated after the step of constructing the Radio Resource Control (RRC) Reconfiguration Relink message and starting the timer, the method further comprises: maintaining the value of the timer until the physical layer problem is resolved, or until the connection re-establishment or handover procedure is performed, or until the Side Link (SL) User Equipment (UE) enters an idle mode; and 46. ​​The method of claim 44 or 45, comprising starting the timer using the existing value if the physical layer problem is resolved or if the connection re-establishment is performed on the same serving cell.

47. A method according to any one of claims 43 to 46, wherein the method comprises suspending the timer if a connection re-establishment procedure or a handover procedure is initiated.

48. when a connection re-establishment or handover procedure with a new serving cell is successful, or when the side link (SL) user equipment (UE) enters a radio resource control (RRC) idle mode without a successful connection re-establishment or handover; checking whether the PC5 configuration obtained from the new serving cell or a System Information Block (SIB) / preconfiguration complies with the configuration of the constructed Radio Resource Control (RRC) reconfiguration sidelink message; restarting the timer with an existing value if the PC5 configuration or the system information block (SIB) / preconfiguration is compliant; 48. The method of any one of claims 45 to 47, comprising the steps of: if the PC5 configuration or the System Information Block (SIB) / preconfiguration is not compliant, constructing a new Radio Resource Control (RRC) reconfiguration sidelink message accordingly; and restarting the timer with the initial value.

49. If the connection re-establishment procedure or the handover procedure fails, switching to Sidelink (SL) mode 2; checking whether the configuration obtained from a System Information Block (SIB) / preconfiguration complies with the configuration of the constructed Radio Resource Control (RRC) reconfiguration sidelink message; if the obtained configuration is compliant, starting the timer with the existing value once sensing results for using Sidelink (SL) Mode 2 are available; 48. The method of claim 45, further comprising the steps of: if the obtained configuration is not compliant, constructing a new Radio Resource Control (RRC) reconfiguration sidelink (SL) message accordingly once sensing results for using SL mode 2 are available; and starting the timer.

50. the sidelink (SL) user equipment (UE) is configured with multiple values ​​for the timer or multiple different timers associated with the same PC5-Radio Resource Control (RRC) procedure; 50. The method of any one of claims 43 to 49, wherein the different values ​​or timers used depend on conditions experienced on the interface between the Sidelink (SL) User Equipment (UE) and the network.

51. 51. The method of claim 43, wherein the sidelink (SL) user equipment (UE) is configured to extend the timer upon the detection of a physical layer problem or the initiation of the connection re-establishment or handover procedure if the Radio Resource Control (RRC) Reconfiguration sidelink message is sent to lower layers and the timer has started.

52. at least one processor; at least one memory containing computer program code, The at least one memory and computer program code, together with the at least one processor, cause the device to: determining whether there is a radio problem at the interface between a Side Link (SL) User Equipment (UE) and a network node; generating or constructing a Radio Resource Control (RRC) reconfiguration sidelink message if it is determined that there are no radio problems on the interface; starting a timer used to monitor the PC5-Radio Resource Control (RRC) configuration procedure; if a radio problem occurs on the interface after starting the timer, sending a scheduling request to a network node and maintaining the timer; and a step of restarting or resetting the maintained timer upon receiving a grant from the network node.

53. The at least one memory and computer program code, together with the at least one processor, cause the device to: detecting that there is a radio problem of the interface between the Side Link (SL) User Equipment (UE) and a network node; and 53. The apparatus of claim 52, further comprising at least the step of: holding the value of the timer until the radio problem with the interface is resolved.

54. 54. The apparatus of claim 53, wherein the detecting that there is a radio problem on the interface comprises detecting a physical layer problem or the initiation of a connection re-establishment or handover procedure over a Uu interface.

55. If a physical layer problem is detected or if a connection re-establishment procedure or a handover procedure is initiated after the steps of constructing the Radio Resource Control (RRC) Reconfiguration sidelink message and starting the timer, the at least one memory and computer program code, together with the at least one processor, cause the device to: maintaining the value of the timer until the physical layer problem is resolved, or until the connection re-establishment or handover procedure is performed, or until the device enters an idle mode; and 55. The apparatus of claim 53 or 54, further configured to at least perform the step of restarting the timer using the existing value if the physical layer problem is resolved or if the connection re-establishment is performed on the same serving cell.

56. 56. The apparatus of claim 52, wherein the at least one memory and computer program code, together with the at least one processor, cause the apparatus to perform at least the step of suspending the timer when a connection re-establishment procedure or a handover procedure is initiated.

57. Upon successful connection re-establishment or handover procedure with a new serving cell, or if the device enters a Radio Resource Control (RRC) idle mode without successful connection re-establishment or handover, the at least one memory and computer program code, together with the at least one processor, cause the device to: checking whether the PC5 configuration obtained from the new serving cell or a System Information Block (SIB) / preconfiguration complies with the configuration of the constructed Radio Resource Control (RRC) reconfiguration sidelink message; restarting the timer with the existing value if the PC5 configuration or the System Information Block (SIB) / preconfiguration is compliant; 57. The apparatus of claim 54, further comprising: if the PC5 configuration or the System Information Block (SIB) / preconfiguration is not compliant, at least the steps of: constructing a new Radio Resource Control (RRC) reconfiguration sidelink message accordingly; and restarting the timer with the initial value.

58. If the connection re-establishment procedure or the handover procedure fails, the at least one memory and computer program code, together with the at least one processor, cause the device to: switching to Sidelink (SL) mode 2; checking whether the configuration obtained from a System Information Block (SIB) / preconfiguration complies with the configuration of the constructed Radio Resource Control (RRC) reconfiguration sidelink message; if the obtained configuration is compliant, starting the timer with the existing value once sensing results for using Sidelink (SL) Mode 2 are available; 57. The apparatus of claim 54, wherein, if the acquired configuration is non-compliant, the apparatus at least performs the steps of: constructing a new Radio Resource Control (RRC) reconfiguration sidelink (SL) message and starting the timer once the sensing result for using SL mode 2 is available.

59. the device is configured with multiple values ​​for the timer or multiple different timers associated with the same PC5-Radio Resource Control (RRC) procedure; A method according to any one of claims 52 to 58, wherein the different values ​​or timers used depend on conditions experienced at the interface between the device and the network.

60. 60. The method of any one of claims 52 to 59, wherein the device is configured to extend the timer upon the detection of a physical layer problem or the initiation of the connection re-establishment or handover procedure if the Radio Resource Control, RRC, reconfiguration sidelink message is sent to lower layers and the timer started.

61. An apparatus comprising: means for determining the presence or absence of radio problems at the interface between said device and a network node; means for generating or formulating a Radio Resource Control (RRC) reconfiguration sidelink message if it is determined that there are no radio problems on the interface; and means for starting a timer used to monitor the PC5-Radio Resource Control (RRC) configuration procedure; means for transmitting a scheduling request to the network node and maintaining the timer if a radio problem occurs on the interface after starting the timer; and means for restarting or resetting the maintained timer upon receiving a grant from the network node.

62. means for detecting a radio problem of an interface between said Side Link (SL) User Equipment (UE) and a network node; and 62. The apparatus of claim 61, further comprising: means for holding the value of the timer until the radio problem with the interface is resolved.

63. 63. The apparatus of claim 62, wherein the means for detecting that there is a radio problem on the interface comprises means for detecting a physical layer problem or the initiation of a connection re-establishment procedure or a handover procedure over a Uu interface.

64. if a physical layer problem is detected or if a connection re-establishment procedure or a handover procedure is initiated after constructing the Radio Resource Control (RRC) Reconfiguration sidelink message and starting the timer, the device means for holding the value of the timer until the physical layer problem is resolved, or until the connection re-establishment or handover procedure is performed, or until the device enters an idle mode; and 64. The apparatus of claim 62 or 63, comprising means for restarting the timer using the existing value if the physical layer problem is resolved or if the connection re-establishment is performed on the same serving cell.

65. An apparatus according to any one of claims 61 to 64, comprising means for suspending said timer if a connection re-establishment procedure or a handover procedure is initiated.

66. When a connection re-establishment or handover procedure with a new serving cell is successful, or when the device enters a radio resource control (RRC) idle mode without a successful connection re-establishment or handover, the device: means for checking whether the PC5 configuration obtained from the new serving cell or a System Information Block (SIB) / preconfiguration complies with the configuration of the constructed Radio Resource Control (RRC) reconfiguration sidelink message; means for restarting the timer with the existing value if the PC5 configuration or the System Information Block (SIB) / preconfiguration is compliant; and 66. The apparatus of claim 63, further comprising means for, if the PC5 configuration or the System Information Block (SIB) / preconfiguration is not compliant, constructing a new Radio Resource Control (RRC) reconfiguration sidelink message accordingly and restarting the timer with the initial value.

67. If the connection re-establishment procedure or the handover procedure fails, the device: means for switching to Sidelink (SL) Mode 2; means for checking whether the configuration obtained from a System Information Block (SIB) / preconfiguration complies with the configuration of the constructed Radio Resource Control (RRC) reconfiguration sidelink message; means for starting the timer with the existing value once sensing results for using Side Link (SL) Mode 2 are available if the obtained configuration is compliant; 66. The apparatus of claim 63, further comprising: means for constructing a new Radio Resource Control (RRC) reconfiguration sidelink (SL) message and means for starting the timer if the obtained configuration is not compliant and if the sensing result for using SL mode 2 is available.

68. the device is configured with multiple values ​​for the timer or multiple different timers associated with the same PC5-Radio Resource Control (RRC) procedure; A method according to any one of claims 61 to 67, wherein the different values ​​or timers used depend on conditions experienced at the interface between the device and the network.

69. 69. The method of any one of claims 61 to 68, wherein the device is configured to extend the timer upon the detection of a physical layer problem or the initiation of the connection re-establishment or handover procedure if the Radio Resource Control, RRC, reconfiguration sidelink message is sent to a lower layer and the timer started.

70. A computer program having stored thereon instructions for carrying out at least the method according to any one of claims 1 to 6, 19 to 26 or 43 to 51.

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