Declaration of sidelink radio link failure in sidelink carrier aggregation

Abstract

Declaration of sidelink radio link failure in sidelink carrier aggregation is provided. A method for declaring sidelink radio link failure in sidelink carrier aggregation may include grouping a plurality of carrier components used in carrier aggregation into different subsets of carrier components, based on at least one common characteristic associated with each respective plurality of carrier components that have been grouped into respective subsets of carrier components. At least one subset of carrier components may include more than one carrier components of at least one common characteristic. A radio link failure may be declared, upon determining a failure of at least one carrier component is detected in more than one of the respective subsets of carrier components.

Description

TITLE:DECLARATION OF SIDELINK RADIO LINK FAILURE IN SIDELINKCARRIER AGGREGATIONTECHNICAL FIELD:

[0001] Some example embodiments may generally relate to mobile or wireless telecommunication systems, such as Long Term Evolution (LTE) or fifth generation (5G) new radio (NR) access technology, or 5G beyond, or other communications systems. For example, certain example embodiments may relate to the declaration of sidelink radio link failure in sidelink carrier aggregation.BACKGROUND:

[0002] Examples of mobile or wireless telecommunication systems may include the Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN), Long Term Evolution (LTE) Evolved UTRAN (E-UTRAN), LTE- Advanced (LTE- A), MulteFire, LTE- A Pro, and / or fifth generation (5G) radio access technology or new radio (NR) access technology. Fifth generation (5G) wireless systems refer to the next generation (NG) of radio systems and network architecture. 5G network technology is mostly based on new radio (NR) technology, but the 5G (or NG) network can also build on E-UTRAN radio. It is estimated that NR may provide bitrates on the order of 10-20 Gbit / s or higher, and may support at least enhanced mobile broadband (eMBB) and ultra-reliable low-latency communication (URLLC) as well as massive machine-type communication (mMTC). NR is expected to deliver extreme broadband and ultra-robust, low-latency connectivity and massive networking to support the Internet of Things (IoT).SUMMARY:

[0003] Various exemplary embodiments may provide an apparatus including at least one processor and at least one memory. The memory may store instructions that, when executed by the at least one processor, cause the apparatus at least to group a plurality of carrier components used in carrier aggregation into different subsets ofcarrier components, based on at least one common characteristic associated with each respective plurality of carrier components that have been grouped into respective subsets of carrier components. At least one subset of carrier components may include more than one carrier components of at least one common characteristic. The apparatus may also be caused to declare a radio link failure, upon determining a failure of at least one carrier component is detected in more than one of the respective subsets of carrier components.

[0004] Certain exemplary embodiments may provide an apparatus including at least one processor and at least one memory. The memory may store instructions that, when executed by the at least one processor, cause the apparatus at least to configure a user equipment for at least one common characteristic of a plurality of carrier components used in carrier aggregation to group a plurality of carrier components used in carrier aggregation into different subsets of carrier components, based on at least one common characteristic associated with each respective plurality of carrier components that have been grouped into respective subsets of carrier components. At least one subset of carrier components may include more than one carrier components of at least one common characteristic. The apparatus may also be caused to receive a declaration of radio link failure from the user equipment upon determining that a failure of at least one carrier component is detected in more than one of the respective subsets of carrier components.

[0005] Some exemplary embodiments may provide an apparatus including means for grouping a plurality of carrier components used in carrier aggregation into different subsets of carrier components, based on at least one common characteristic associated with each respective plurality of carrier components that have been grouped into respective subsets of carrier components. At least one subset of carrier components may include more than one carrier components of at least one common characteristic. The apparatus may also include means for declaring a radio link failure, upon determining a failure of at least one carrier component is detected in more than one of the respective subsets of carrier components.

[0006] Various exemplary embodiments may provide an apparatus including meansfor configuring a user equipment for at least one common characteristic of a plurality of carrier components used in carrier aggregation to group a plurality of carrier components used in carrier aggregation into different subsets of carrier components, based on at least one common characteristic associated with each respective plurality of carrier components that have been grouped into respective subsets of carrier components. At least one subset of carrier components may include more than one carrier components of at least one common characteristic. The apparatus may also include means for receiving a declaration of radio link failure from the user equipment upon determining that a failure of at least one carrier component is detected in more than one of the respective subsets of carrier components.BRIEF DESCRIPTION OF THE DRAWINGS:

[0007] For proper understanding of example embodiments, reference should be made to the accompanying drawings, as follows:

[0008] FIG. 1 illustrates an example of a plurality of carrier components, according to various exemplary embodiments;

[0009] FIG. 2A illustrates an example of packet duplication for SL CA, according to various exemplary embodiments;

[0010] FIG. 2B illustrates an example of packet splitting for SL CA, according to various exemplary embodiments;

[0011] FIG. 3 illustrates a flow diagram of one or more procedures for determining and declaring SL RLF, according to various exemplary embodiments;

[0012] FIG. 4 illustrates a signal diagram of one or more procedures for determining and declaring SL RLF in a network configuration, according to certain exemplary embodiments;

[0013] FIG. 5 illustrates an example of a flow diagram of a method, according to various exemplary embodiments;

[0014] FIG. 6 illustrates an example of a flow diagram of another method, according to certain exemplary embodiments; and

[0015] FIG. 7 illustrates a set of apparatuses, according to various exemplaryembodiments.DETAILED DESCRIPTION:

[0016] It will be readily understood that the components of certain example embodiments, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. The following is a detailed description of some exemplary embodiments of systems, methods, apparatuses, and non-transitory computer program products for declaring sidelink (SL) radio link failure (RLF) in SL carrier aggregation (CA). Although the devices discussed below and shown in the figures refer to 5G or Next Generation NodeB (gNB) devices and user equipment devices, this disclosure is not limited to only gNBs and UEs.

[0017] It may be readily understood that the components of certain example embodiments, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Different reference designations from multiple figures may be used out of sequence in the description, to refer to a same element to illustrate their features or functions. If desired, the different functions or procedures discussed herein may be performed in a different order and / or concurrently with each other. Furthermore, if desired, one or more of the described functions or procedures may be optional or may be combined. As such, the following description should be considered as illustrative of the principles and teachings of certain example embodiments, and not in limitation thereof.

[0018] In 5G / NR technology, device-to-device communications, such as UE to UE, V2V, V2X, and the like, may be referred to as SL communications. NR SL communications may be performed by unicast, groupcast, and broadcast. In unicast, a device, such as a UE, may target communications directly to a specific receiving device to receive the communications. In groupcast, the UE may target a group of receiving devices to receive the communications. In broadcast, the UE may target any and all devices that may be within a range of transmission relative to the UE.

[0019] As part of SL transmissions, the devices, such as UEs, may inter-coordinate with each other to determine resource information and allocation for the sidelink transmission. Carrier aggregation (CA) may be implemented to increase the data rate per device by configuring the UE to be simultaneously connected with multiple cells of a serving base station. The UE may operate at multiple frequencies at the same time. CA may allow the UE to simultaneously transmit and receive data on multiple carrier components (CCs) from a node or base station. The traffic between the UE and the base station splits between multiple carriers in the medium access control (MAC) layer. The UE may allocate downlink (DL) and uplink (UL) resources on an aggregated resource, which may include two or more carrier components.

[0020] A channel busy ratio (CBR) may be a metric used to determine or indicate a channel state, which may be used to allocate aggregated resources. The CBR may identify the ratio of time a channel is congested or busy as compared to an overall time of observation or measurement. SL carrier selection (or reselection) and packet duplication may be specified for SL broadcast to serve the V2X communication over SL. A known design for LTE SL CA was based on an LTE SL broadcast solution, of which SL RRC procedure was not supported between a SL transmitter (Tx) UE and SL receiver (Rx) UE for SL CA configuration. In LTE SL, no detection of LTE SL RLF was supported. In NR SL CA, carrier selection (or reselection) and packet duplication may be implemented for all cast types, such as SL broadcast, groupcast and unicast, and SL RRC procedure may be supported in NR SL unicast. In NR SL for unicast, the detection of NR SL RLF may be supported when a maximum number of hybrid automatic repeat request (HARQ) discontinuous transmission (DTX) or a maximum number of radio link control (RLC) retransmissions is reached.

[0021] In NR, when packet data convergence protocol (PDCP) packet duplication is activated, a PDCP transmitter may generate duplicates of PDCP protocol data units (PDUs) and transmit the duplicates on a different Radio Link Control (RLC) entity and associated logical channel (also referred to as “RLC bearer”). A PDCP receiver may eliminate duplicate packets. The use of PCDP packet duplication may enhance reliability and reduce latency. In PDCP packet duplication for a Uu interface and forCA, RLF may not be triggered when the maximum number of RLC retransmissions is reached. The number of HARQ DTX may be counted per carrier, and legacy SL RLF may not be declared when the counting is reached to the maximum number of HARQ DTX and the UE has other available SL carriers for SL CA. SL RLF may be based on failures in a specific number of carriers or in all carriers.

[0022] In SL CA, it is desirable to establish the SL connection for as long as SL TX and RX UEs can still communicate with good quality using one or more carriers. SL RLF may not need to be declared if failure only occurs in some, but less than all, of the carriers and is not expected in the other carrier(s). However, it is desirable to quickly detect and declare SL RLF in order to more quickly perform an action based on the SL RLF detected and / or improve resource utilization on a failed connection.

[0023] In an attempt to address these concerns, a network entity (NW), such as a base station or gNB, may configure a threshold N in terms of the number of carriers and the UE may declare the RLF when the number of carriers where the failure occurs, such as DTX error, reaches a maximum value, which meets the threshold N. However, this may require signaling to the NW to indicate time-varying characteristics of the carriers where the TX UE and RX UE communicate. This may result in unnecessary RLF or delayed RLF detection if the gNB is not aware of up- to-date information of carrier situation. Alternatively, the SL UE may determine RLF without the threshold N.

[0024] Various exemplary embodiments may provide technological advantages to implement one or more procedures for the SL UE operating in SL CA to determine and declare SL RLF based on failure detected in one, a plurality, or all carriers, and with as low interruption as possible in sufficient time to perform any necessary actions to resolve or overcome the RLF.

[0025] Certain exemplary embodiments may provide that the transmission and reception of SL transmissions on different carriers may be performed by the same pair of SL Tx UEs and Rx UEs in SL CA. Channel conditions of different carriers in SL CA may depend on the characteristics of the carriers, such as the frequency band, the maximum allowed transmission power, and / or the potential interference, and thelike. For example, when the carrier characteristics are similar across different carriers, the detection of failure in the carriers may be correlated to each other. Alternatively, the failure in different carriers may be independent of each other.

[0026] FIG. 1 illustrates an example of a plurality of carrier components, according to various exemplary embodiments. The carrier components (101a. . . lOlx) may be used in CA and may allow a UE to transmit and / or receive data on multiple carrier components 101a... 10 lx from a node or base station. The carrier components 101a. . . 10 lx may be divided into a plurality of groups 102, such as, for example, a first group 103, a second group 104, and a third group 105. Each of the plurality of groups 102 may include a subset of more than one of the carrier components 101a... lOlx, such as, for example, the first group 103 may include carrier components 101b... 10 le, the second group 104 may include carrier components lOlj. . . 101k, and the third group 105 may include carrier components 101m. . . lOln, as shown in FIG. 1. The subsets of the carrier components {(101b. . . 10 le), ( 10 Ij ... 10 Ik), ( 10 Im ... 10 In) } in each group 103 / 104 / 105 may be different or unique from each other. The carrier components {(101b. . . 10 le), (lOlj. . . 101k), (101m... 101n){ may be grouped into the subsets based on at least one common characteristic associated with each respective plurality of carrier components {(101b... lOle), (10 Ij . . . 10 Ik), (101m... 101n){ that have been grouped into respective subsets of carrier components 103 / 104 / 105.

[0027] Various exemplary embodiments may provide that the SL Tx UE determines on which carrier(s) the detected failure can be used to declare SL RLF based on the difference of the carrier characteristics of the used carriers in SL CA. For example, the carrier characteristics may include, but is not limited to, the frequency band, the transmission power, and / or the radio link condition, such as the received power of wanted signal and interference level.

[0028] In certain exemplary embodiments, the carrier components used in SL CA may have different frequency bands, which may for example, include inter-band CA. The SL Tx UE may declare the SL RLF if failure is detected on at least one carrier of each frequency band. SL RLF may be declared based on a specified number of carrierscorresponding to the number of frequency bands and the failed carriers should be distributed in all the frequency bands corresponding to the selected carrier.

[0029] In various exemplary embodiments, the carrier components used in SL CA may be in either the same frequency band (e.g., intra-band SL CA) or different frequency bands (e.g., inter-band CA). The difference of SL Tx power or power spectral density (PSD) in different carriers may be used by the SL Tx UE to determine how many of the carriers and / or on which carrier(s) the detected failure will lead to the declaration of SL RLF. The determination of how many of the carriers and / or on which carrier(s) the detected failure will lead to the declaration of SL RLF may be based on one or more metrics, which may include transmission power levels, PSD, a power configuration, a CBR, and the like. As a first example, the SL Tx power levels of the SL transmissions on each carrier before the failure was detected on at least one carrier may be used to determine how many of the carriers and / or on which carrier(s) the detected failure will lead to the declaration of SL RLF. As a second example, the SL Tx PSD of the SL transmissions on each carrier before the failure was detected on at least one carrier may be used to determine the carriers on which the failure occurred. As a third example, the SL Tx power configuration for a selected SL resource pool (RP) on each carrier may be used to determine the Tx power difference or PSD difference. The SL Tx power configuration may be, for example, a maximum allowed Tx power. As a fourth example, the Tx power difference or PSD difference may be determined based on a configured maximum SL Tx power for CBR-based congestion control. The allowed maximum SL Tx power may depend on measuring a value of the CBRs of SL RP of each selected carrier.

[0030] According to various exemplary embodiments, in each of the above examples the SL Tx UE may be configured, or pre-configured, with a Tx power or PSD offset value on different carriers to determine the failure of correlated carriers. The Tx UE may derive / determine the number of failed carriers or on which carrier(s) the detected failure will lead to declaring SL RLF based on the Tx power or PSD offset and the used or allowed Tx power or PSD in each carrier. Certain exemplary embodiments may provide that if the selected carriers for SL CA are either in the same frequencyband or in the different frequency band, the difference of measured CBRs may be used by the SL Tx UE to determine how many of the carriers and / or on which carriers the detected failure will lead to declaring SL RLF. Some exemplary embodiments may provide that the SL Tx UE may be configured, or pre-configured, with a CBR offset on different carriers to determine the failure of correlated carriers. Based on the CBR offset and the measured CBR of the SL RP on each carrier, the Tx UE can derive the number of failed carriers or on which carrier(s) the detected failure will lead to declaration of SL RLF.

[0031] In some exemplary embodiments, the configuration of difference offsets may include at least one of difference offsets in terms of the frequency bands, the Tx powers, and / or CBRs. The configuration of difference offsets may be pre-configured to the SL UEs commonly or individually. Alternatively, the configuration of difference offsets may be configured by the NW via broadcasted common signaling (e.g., system information) or dedicated signaling (e.g., RRC message). If the dedicated signaling is used to configure the difference offsets, the configuration may be provided to the SL UEs before or after SL CA is activated. The reconfiguration may be provided to the SL UEs when the SL UE reports the selected carriers for SL CA. The configuration of difference offsets may be based on UE implementation.

[0032] FIG. 2A illustrates an example of packet duplication for SL CA, according to various exemplary embodiments. FIG. 2B illustrates an example of packet splitting for SL CA, according to various exemplary embodiments. Difference offsets of the frequency bands, the Tx power or PSD levels and / or CBRs may be configured differently for the SL CA for packet duplication as compared to packet splitting, which may cause SL RLF to be triggered differently for packet duplication in SL CA and for packet split in SL CA. For example, the different configurations may result in declaring SL RLF when failure on all of the carrier components is detected in the case of packet duplication, whereas, for example, SL RLF may be declared when failure on only some of the carrier components are detected in the case of packet splitting. As shown in FIGs. 2A and 2B, in the one or more UEs 203 / 213 performing the packet duplication and / or packet splitting, an indication from an access stratumlayer 202, such as PDCP, RLC, MAC, and / or PHY, may be transmited to a non- access stratum (NAS) layer 201 locally at the UE indicating that the SL RLF is declared. When the one or more UEs 203 / 213 declares the SL RLF in access stratum layer, the UE 203 / 213 may report the RLF to the upper layer (e.g., NAS). In addition, the UE 203 / 213 may also report the SL RLF to a serving NW node if the UE 203 / 213 is in an RRC CONNECTED state. The upper layer (NAS) and / or the NW node may perform the necessary actions to recover the RLF or release the connection or services to the relevant UEs 203 / 213.

[0033] Various exemplary embodiments may provide that different SL carrier components may be configured by the NW or pre-configured to the SL Tx UE into the different group. The configured carrier group may be used by the SL Tx UE to determine SL RLF, which may be an alternative, or in addition, to using the difference offsets to determine failure correlated carrier groups. Based on the configured difference offsets, the SL Tx UE may group the selected carriers in SL CA to the failure correlated carrier groups, which may be performed in MAC layer. As an example, the carrier components may be grouped according to their respective frequency bands. For instance, the carrier components in frequency range 1 (FR1) may be in one failure correlated carrier group and carrier components in frequency range 2 (FR2) may be in another one or more carrier groups. As another example, the carrier components may be grouped according to the Tx power or PSD difference offset. For instance, the carrier components of which the used Tx power or allowed maximum Tx power or the derived PSD are less than the configured difference offset may be grouped into the same carrier group. As a further example, the carrier components may be grouped according to the CBR difference offset. For instance, the carrier components having measured CBRs that are less than the configured difference offset may be grouped into the same carrier group. Alternatively, the carrier components having measured CBRs leading to the similar Tx parameters according to SL congestion control configuration may be grouped into the same carrier group. For example, the similar Tx parameters may be one or more of maximum number of retransmissions, maximum Tx power, modulation and codingscheme (MCS) range and / or range of a number of sub-channels, and the like. As another example, for the carrier components in FR2, the carrier components may be grouped according to radio frequency (RF) panels that the SL transmission is used in each carrier. For instance, the carrier components that use the same RF panels may be grouped into the same carrier group.

[0034] As an example, the groups 103 / 104 / 105 of carrier components {(101b. . . lOle), (lOlj. . . 101k), (101m. .. 10 In)} shown in FIG. 1 may be grouped based on at least one common characteristic associated with each respective plurality of carrier components {(101b. . . lOle), (lOlj. . . 101k), (101m. . . 101n)} that have been grouped into respective subsets of carrier components (103 / 104 / 105). For example, the at least one common characteristic may be a frequency band, such that each of the different subsets of carrier components (103 / 104 / 105) corresponds to a different frequency band. As another example, the at least one common characteristic may be a difference offset in transmission power between different carriers relative to a transmission power of a particular reference carrier component (e.g., 10 Id) from among the plurality of carrier components (101a. . . lOlx), such that each of the different subsets of carrier components (103 / 104 / 105) corresponds to a specified difference offset (Atp) in transmission power based on the particular reference carrier component ( 10 Id). As a further example, the at least one common characteristic may be a difference offset in PSD between different carriers relative to a PSD of a particular reference carrier component (e.g., 10 Id) from among the plurality of carrier components (101a. . . lOlx), such that each of the different subsets of carrier components (103 / 104 / 105) corresponds to a specified difference offset (Apsd) in PSD based on the particular reference carrier component (10 Id). A further example of the at least one common characteristic may be a difference offset in measured CBR over a resource pool on each of the plurality of carrier components (101a. . . lOlx) relative to a CBR over a resource pool on a particular reference carrier component (e.g., 10 Id), such that the measured CBR of carrier components in different subsets (103 / 104 / 105) of carrier components (101a. . . lOlx) corresponds to a specified difference offset (Acbr) in measured CBR based on the particular reference carriercomponent (10 Id). AS an even further example, the at least one common characteristic may be a measured CBR of a particular reference carrier component (e.g., 10 Id) from among the plurality of carrier components (101a. . . lOlx), such that each of the different subsets of the carrier components (103 / 104 / 105) corresponds to a different measured CBR (cbrl...cbm) based on the particular reference carrier component (10 Id).

[0035] Certain exemplary embodiments may provide that the SL Tx UE may determine the number of failed carriers for SL RLF declaration based on the number of the failure correlated carrier groups among the selected carrier components for SL CA. For example, if the SL Tx UE identified N carrier groups among the selected carriers for SL CA, the SL Tx UE may need to detect failure in at least N carrier components and also at least one failed carrier component may need to be detected in each failure correlated carrier group to declare SL RLF. Upon detection of the failure in one carrier component, the SL Tx UE may check the carrier failure status in other carrier groups. If there is any other carrier group that all the carrier components are available without failure, the SL Tx UE may not declare SL RLF and the SL Tx UE may be triggered for carrier reselection. In the carrier failure trigger carrier reselection, the failed carrier component(s) may not be reselected for a certain time period that can be defined by specification or (pre-)configured to the SL Tx UE, such as by a timer. On the other hand, if all the carrier groups have at least one carrier component in which failure is detected, the SL RLF may be declared.

[0036] In certain exemplary embodiments, it is specified or (pre-)configured that the SL Tx UE may declare the SL RLF based on failure detected in all of the carrier components. The SL Tx UE may be further (pre-)configured to be updated with carrier failure detection criteria. For example, when failure is detected in one carrier component, the maximum number of HARQ DTX and / or maximum number of RLC retransmissions used for detection failure in other carrier components may be updated with the configured delta difference. The original or previous configuration of maximum number of HARQ DTXs / RLC retransmissions may be M and the configured delta may be X. The updated maximum number of HARQ DTXs / RLCretransmissions for failure detection in other carrier components may be calculated by M-X when failure is detected in one carrier.

[0037] In various exemplary embodiments, the common delta may be configured for all of the carrier components. In certain exemplary embodiments, the different delta may be configured for different carrier groups. In some exemplary embodiments, the delta may be configured for each carrier component separately, either corresponding to the carrier component(s) that updates the counter of the maximum number of HARQ DTXs / RLC retransmissions or corresponding to the failed carrier component(s). Whether or not the maximum number of RLC retransmissions will be configured for detecting the carrier failure may depend on whether the RLC entity will be reset when the carrier component is re-selected.

[0038] Some exemplary embodiments may provide that the SL RLF may not be declared if HARQ ACK and / or ARQ ACK in the RLC layer is received in one of the carrier components when failure is detected in another carrier component.

[0039] FIG. 3 illustrates a flow diagram of one or more procedures for determining and declaring SL RLF, according to various exemplary embodiments. The one or more procedures may be performed by one or both of a network node (e.g., NW or gNB) and / or an SL Tx UE or another SL-capable UE, such as UE 203 / 213 in FIG. 2. At 310, multiple carrier components (101a. . . lOlx of FIG. 1) may be selected for SL CA, and at 320, one or more difference offsets may be configured or pre-configured for determining SL RLF in SL CA. At 330, the selected carrier components (e.g., lOlb-e, lOlj, 101k, 101m, lOln) from all of the carrier components (101a... lOlx of FIG. 1) may be grouped into different groups (102-105 of FIG. 1) based on the one or more difference offsets. At 340, failure may be detected or determined in at least one carrier in at least one of the carrier groups (102-105 of FIG. 1), and at 350, it is determined whether a last one of the groups has been detected to include a failure in a selected carrier components (e.g., lOlb-e, lOlj, 101k, 101m, lOln).

[0040] If at least one failure has not been detected in all of the carrier groups (102- 105 of FIG. 1), then the procedure may return to step 340 to continue detecting for failures in carrier components (e.g., lOlb-e, lOlj, 101k, 101m, lOln) of the carriergroups (102-105 of FIG. 1). If at least one failure has been found in all of the carrier groups (102-105 of FIG. 1), the procedure continues to step 360. At 360, SL RLF may be declared based on detecting / determining that at least one failure exists in all of the carrier groups (102-105 of FIG. 1).

[0041] FIG. 4 illustrates a signal diagram of one or more procedures for determining and declaring SL RLF in a network configuration, according to certain exemplary embodiments. The network may be formed by at least a network entity (NW) 401 and an SL UE 402 (similar to UEs 203 / 213 of FIG. 2). At 410, the NW 401 communicates with the SL UE 402 (203 / 213 of FIG. 2) to configure the SL UE 402 (203 / 213 of FIG. 2) using a system information block (SIB) and / or RRC reconfiguration signaling. Alternatively, the SL UE 402 (203 / 213 of FIG. 2) may be pre-configured or configured by UE implementation. The configuration includes an indication of difference offsets, such as the frequency band, Tx power, PSD, CBR, and the like, and / or a carrier group designation. At 420, the SL UE 402 (203 / 213 of FIG. 2) may select multiple carrier components (101a... lOlx of FIG. 1) for SL CA (similar to 310 of FIG. 3). At 430 (similar to 330 of FIG. 3), the SL UE 402 (203 / 213 of FIG. 2) may group the selected carrier components (e.g., lOlb-e, lOlj, 101k, 101m, lOln) from all of the carrier components (101a. . . lOlx of FIG. 1) into different groups (102-105 of FIG. 1) based on the one or more difference offsets, or based on the carrier group designation in the configuration.

[0042] At 440 (similar to 360 of FIG. 3), the SL UE 402 (203 / 213 of FIG. 2) may declare SL RLF if failure is detected / determined in one or more of the selected carrier components (e.g., lOlb-e, lOlj, 101k, 101m, lOln) from all of the different groups (102-105 of FIG. 1). For example, if the selected carrier components (e.g., lOlb-e, lOlj, 101k, 101m, lOln) are grouped into two groups (103 / 104 of FIG. 1), SL RLF may be declared when a failure is detected for at least one of the selected carrier components (e.g., lOlb-e, 10 Ij, 101k, 101m, 10 In) in each of the two groups (103 / 104 of FIG. 1). At 450, the SL UE 402 (203 / 213 of FIG. 2) may transmit an indication of SL RLF to the NW 401, and at 460, the NW 401 may perform one or more procedures or actions to recover the RLF or release connection with the SL UE402 (203 / 213 of FIG. 2).

[0043] Various exemplary embodiments may provide technological advantages for an SL UE operating in SL CA to determine and declare SL RLF based on failure detected in one, a plurality, or all carrier components in each of the different groups of selected carrier components. Certain exemplary embodiments may provide for as low interruption as possible while providing sufficient time to perform any necessary actions to resolve or overcome the SL RLF.

[0044] FIG. 5 illustrates an example flow diagram of a method, according to certain exemplary embodiments. In an example embodiment, the method of FIG. 5 may be performed by a network element, or a group of multiple network elements in a 3 GPP system, such as LTE or 5G-NR. For instance, in an exemplary embodiment, the method of FIG. 5 may be performed by a user device, mobile device, etc., such as an ambient loT UE, similar to apparatus 710 illustrated in FIG. 7.

[0045] According to various exemplary embodiments, the method of FIG. 5 may include, at 510, grouping (330 / 430 / 510) a plurality of carrier components (101a... lOlx) used in carrier aggregation (310) into different subsets of carrier components (103 / 104 / 105), based on at least one common characteristic (320 / 410) associated with each respective plurality of carrier components {(101b... lOle), (10 Ij . . . 10 Ik), (101m... 101n)} that have been grouped into respective subsets of carrier components (103 / 104 / 105). At least one subset of carrier components (103) may include more than one carrier components (101b, 101c) of at least one common characteristic. At 520, the method may further include declaring (360 / 440 / 520) a radio link failure, upon determining a failure of at least one carrier component (101b, lOlc / lOlj) is detected (340) in more than one of the respective subsets of carrier components (103 / 104).

[0046] Certain exemplary embodiments may provide that the at least one common characteristic comprises one or more of: frequency band, transmission power, power spectral density, channel busy ratio, or radio link condition. The at least one common characteristic associated with each respective plurality of carrier components {(101b... 10 le), (10 Ij . . . 10 Ik), (101m... 10 In)} that comprise the respective subsetsof carrier components (103 / 104 / 105) being one or more of: (a) a frequency band, such that each of the different subsets of carrier components (103 / 104 / 105) corresponds to a different frequency band; (b) a difference offset (step 410) in transmission power between different carriers relative to a transmission power of a particular reference carrier component (10 Id) from among the plurality of carrier components (101a... lOlx), such that each of the different subsets of carrier components (103 / 104 / 105) corresponds to a specified difference offset (Atp) in transmission power based on the particular reference carrier component (10 Id); (c) a difference offset (step 410) in power spectral density between different carriers relative to a power spectral density of a particular reference carrier component (10 Id) from among the plurality of carrier components (101a. .. 10 lx), such that each of the different subsets of carrier components (103 / 104 / 105) corresponds to a specified difference offset (Apsd) in power spectral density based on the particular reference carrier component (10 Id); (d) a difference offset (step 410) in measured channel busy ratio over a resource pool on each of the plurality of carrier components (101a. . . lOlx) relative to a channel busy ratio over a resource pool on a particular reference carrier component (10 Id), such that the measured channel busy ratio of carrier components in different subsets (103 / 104 / 105) of carrier components (101a. . . lOlx) corresponds to a specified difference offset (Acbr) in measured channel busy ratio based on the particular reference carrier component (10 Id); or (e) a measured channel busy ratio (step 410) of a particular reference carrier component (10 Id) from among the plurality of carrier components (101a. . . 10 lx), such that each of the different subsets of the carrier components (103 / 104 / 105) corresponds to a different measured channel busy ratio (cbrl . . .cbm) based on the particular reference carrier component ( 101 d).

[0047] In an exemplary illustration, the measurements may be on carrier components (CC) which may be selected and used for carrier aggregation (CA) transmissions. For example, CC1 (10 Id) and CC2 (101b) may be used for CA transmissions. If CC1 (10 Id) and CC2 (101b) are from the same group 103, then when a failure is detected on CC1 (10 Id) and based on correlation between CC1 (10 Id) and CC2 (101b) as of the same group 103, RLF may be declared before detecting a failure on CC2 (101b).If CC1 (10 Id) and CC2 (lOlj) are from different groups (103 / 104), then RLF may be declared when failures are detected on both CC1 ( 10 Id) and CC2 ( 10 Ij).

[0048] Some exemplary embodiments may provide that the difference offset in the transmission power (Atp) or the power spectral density (Apsd) is based on one of: a power configuration for the resource pool on each of the plurality of carrier components (101a. . . lOlx); a maximum transmission power for the measured channel busy ratio over the resource pool on each of the plurality of carrier components (101a... lOlx); or being pre-configured for the apparatus (203 / 213 / 402) for each of the plurality of carrier components (101a. . . lOlx). The method may further include receiving (410), from an NW (401), a configuration or a pre-configuration comprising the at least one common characteristic of each of the plurality of carrier components (101a . . . lOlx). In a case of packet duplication (FIG. 2A) being configured for a radio bearer transmitted by the apparatus (710), the radio link failure is declared (360 / 440 / 520) when the failure is determined in at least one carrier component in each of the different subsets of carrier components (103 / 104 / 105) that are used for the packet duplication for the radio bearer. Each of duplicated packets for the radio bearer may be transmitted on different subsets of carrier components (103 / 104 / 105).

[0049] Some exemplary embodiments provide that the method may include transmitting (450) an indication to the network entity (401) that the radio link failure is declared. The method may further include transmitting (FIG. 2A) an indication from an access stratum layer (202) to a non-access stratum layer (201) locally at the apparatus that the radio link failure is declared.

[0050] FIG. 6 illustrates an example flow diagram of a method, according to certain exemplary embodiments. In an example embodiment, the method of FIG. 6 may be performed by a network element, or a group of multiple network elements in a 3 GPP system, such as LTE or 5G-NR. For instance, in an exemplary embodiment, the method of FIG. 6 may be performed by another user device, mobile device, etc., such as a relay UE, similar to apparatus 720 illustrated in FIG. 7.

[0051] According to various exemplary embodiments, the method of FIG. 6 may include, at 610, configuring (610) a user equipment (203 / 213 / 402) for at least onecommon characteristic of a plurality of carrier components (101a. . . lOlx) used in carrier aggregation to group (330 / 430 / 510) a plurality of carrier components (101a... lOlx) used in carrier aggregation (310) into different subsets of carrier components (103 / 104 / 105), based on at least one common characteristic (320 / 410) associated with each respective plurality of carrier components {(101b... lOle), (10 Ij . . . 10 Ik), (101m... 101n)} that have been grouped into respective subsets of carrier components (103 / 104 / 105). At least one subset of carrier components (103) may include more than one carrier components (lOlb / lOlc) of at least one common characteristic. At 620, the method may also include receiving (360 / 450 / 620) a declaration of radio link failure from the user equipment (203 / 213 / 402) upon determining that a failure of at least one carrier component (101b, lOlc / lOlj) is detected (340) in more than one of the respective subsets of carrier components (103 / 104).

[0052] Certain exemplary embodiments may provide that the at least one common characteristic comprises one or more of: frequency band, transmission power, power spectral density, channel busy ratio, or radio link condition. The at least one common characteristic is configured for the user equipment (203 / 213 / 402) using a system information block or radio resource control message (320 / 410). The at least one common characteristic associated with each respective plurality of carrier components {(101b. . . lOle), (lOlj. . . 101k), (101m. . . 101n){ that comprise the respective subsets of carrier components (103 / 104 / 105) being one or more of: (a) a frequency band, such that each of the different subsets of carrier components (103 / 104 / 105) corresponds to a different frequency band; (b) a difference offset (step 410) in transmission power between different carriers relative to a transmission power of a particular reference carrier component (10 Id) from among the plurality of carrier components (101a. . . lOlx), such that each of the different subsets of carrier components (103 / 104 / 105) corresponds to a specified difference offset (Atp) in transmission power based on the particular reference carrier component ( 10 Id); (c) a difference offset (step 410) in power spectral density between different carriers relative to a power spectral density of a particular reference carrier component (10 Id)from among the plurality of carrier components (101a. . . 10 lx), such that each of the different subsets of carrier components (103 / 104 / 105) corresponds to a specified difference offset (Apsd) in power spectral density based on the particular reference carrier component (10 Id); (d) a difference offset (step 410) in measured channel busy ratio over a resource pool on each of the plurality of carrier components (101a... lOlx) relative to a channel busy ratio over a resource pool on a particular reference carrier component (10 Id), such that the measured channel busy ratio of carrier components in different subsets of carrier components (103 / 104 / 105) of carrier components (101a. . . lOlx) corresponds to a specified difference offset (Acbr) in measured channel busy ratio based on the particular reference carrier component (10 Id); or (e) a measured channel busy ratio of a particular reference carrier component (lOld) from among the plurality of carrier components (101a. . . lOlx), such that each of the different subsets of the carrier components (103 / 104 / 105) corresponds to a different measured channel busy ratio (cbrl...cbm) based on the particular reference carrier component (10 Id).

[0053] Some exemplary embodiments may provide that the difference offset (410) in the transmission power or the power spectral density is based on one of: a power configuration for the resource pool on each of the respective groups of carrier components {(101b. . . lOle), (lOlj. . . 101k), (101m. . . 101n)}, a maximum transmission power for the measured channel busy ratio over the resource pool on each of the respective groups of carrier components {(101b... lOle), (10 Ij... 101k), (101m. .. 10 In)}, or being pre-configured for the apparatus (203 / 213 / 402) for each of the respective groups of carrier components {(101b. . . lOle), (10 Ij . . . 10 Ik), (101m... 10 In)}. The method may also include performing (460) a procedure to recover the radio link failure or release a connection with the user equipment (203 / 213 / 402) to resolve the radio link failure. The method may also include transmitting (410), to the user equipment (402), a configuration or a pre-configuration comprising the at least one common characteristic of each of the respective groups of carrier components {(101b. . . lOle), (10 Ij . . . 101k), (101m. . . 101n)}.

[0054] FIG. 7 illustrates a set of apparatuses 710 and 720 according to variousexemplary embodiments. In the various exemplary embodiments, the apparatus 710 may be an element in a communications network or associated with such a network, such as a UE, RedCap UE, SL UE, mobile equipment (ME), mobile station, mobile device, stationary device, loT device, or other device. For example, the SL UE 203 / 213 and SL UE 402 according to various exemplary embodiments discussed above may be examples of apparatus 710. It should be noted that one of ordinary skill in the art would understand that apparatus 710 may include components or features not shown in FIG. 7. In addition, apparatus 720 may be a network, network entity, element of the core network, or element in a communications network or associated with such a network, such as a base station, an NW, or a gNB. For example, the NW 401 according to various exemplary embodiments as discussed above may be an example of apparatus 720. It should be noted that one of ordinary skill in the art would understand that apparatus 720 may include components or features not shown in FIG. 7.

[0055] In some example embodiments, apparatuses 710 and / or 720 may include one or more processors, one or more computer-readable storage medium (for example, memory, storage, or the like), one or more radio access components (for example, a modem, a transceiver, or the like), and / or a user interface. In some example embodiments, apparatuses 710 and / or 720 may be configured to operate using one or more radio access technologies, such as GSM, LTE, LTE-A, NR, 5G, WLAN, WiFi, NB-IoT, Bluetooth, NFC, MulteFire, and / or any other radio access technologies.

[0056] As illustrated in the example of FIG. 7, apparatuses 710 and / or 720 may include or be coupled to processors 712 and 722, respectively, for processing information and executing instructions or operations. Processors 712 and 722 may be any type of general or specific purpose processor. In fact, processors 712 and 722 may include one or more of general-purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), and processors based on a multi-core processor architecture, as examples. While a single processor 712 (and 722) for each of apparatuses 710 and / or 720 is shown in FIG. 7, multiple processorsmay be utilized according to other example embodiments. For example, it should be understood that, in certain example embodiments, apparatuses 710 and / or 720 may include two or more processors that may form a multiprocessor system (for example, in this case processors 712 and 722 may represent a multiprocessor) that may support multiprocessing. According to certain example embodiments, the multiprocessor system may be tightly coupled or loosely coupled to, for example, form a computer cluster).

[0057] Processors 712 and 722 may perform functions associated with the operation of apparatuses 710 and / or 720, respectively, including, as some examples, precoding of antenna gain / phase parameters, encoding and decoding of individual bits forming a communication message, formatting of information, and overall control of the apparatuses 710 and / or 720, including processes illustrated in FIGs. 3-6.

[0058] Apparatuses 710 and / or 720 may further include or be coupled to memory 714 and / or 724 (internal or external), respectively, which may be coupled to processors 712 and 722, respectively, for storing information and instructions that may be executed by processors 712 and 722. Memory 714 (and memory 724) may be one or more memories and of any type suitable to the local application environment, and may be implemented using any suitable volatile or nonvolatile data storage technology such as a semiconductor-based memory device, a magnetic memory device and system, an optical memory device and system, fixed memory, and / or removable memory. For example, memory 714 (and memory 724) can be comprised of any combination of random access memory (RAM), read only memory (ROM), static storage such as a magnetic or optical disk, hard disk drive (HDD), or any other type of non-transitory machine or computer readable media. The instructions stored in memory 714 and memory 724 may include program instructions or computer program code that, when executed by processors 712 and 722, enable the apparatuses 710 and / or 720 to perform tasks as described herein.

[0059] In certain example embodiments, apparatuses 710 and / or 720 may further include or be coupled to (internal or external) a drive or port that is configured to accept and read an external computer readable storage medium, such as an optical1 disc, USB drive, flash drive, or any other storage medium. For example, the external computer readable storage medium may store a computer program or software for execution by processors 712 and 722 and / or apparatuses 710 and / or 720 to perform any of the methods illustrated in FIGs. 3-6.

[0060] According to various exemplary embodiments, the apparatus 710 may include at least one processor 712, and at least one memory 714, as shown in FIG. 7. The memory 714 may store instructions that, when executed by the processor 712, cause the apparatus 710 to group (330 / 430 / 510) a plurality of carrier components (101a... lOlx) used in carrier aggregation (310) into different subsets of carrier components (103 / 104 / 105), based on at least one common characteristic (320 / 410) associated with each respective plurality of carrier components {(101b... lOle), (10 Ij . . . 10 Ik), (101m... 101n)} that have been grouped into respective subsets of carrier components (103 / 104 / 105). At least one subset of carrier components (103) may include more than one carrier components (101b, 101c) of at least one common characteristic. The apparatus 710 may also be caused to declare (360 / 440 / 520) a radio link failure, upon determining a failure of at least one carrier component (101b, lOlc / lOlj) is detected (340) in more than one of the respective subsets of carrier components (103 / 104).

[0061] According to various exemplary embodiments, the apparatus 720 may include at least one processor 722, and at least one memory 724, as shown in FIG. 7. The memory 724 may store instructions that, when executed by the processor 722, cause the apparatus 720 to configure (610) a user equipment (203 / 213 / 402) for at least one common characteristic of a plurality of carrier components (101a. . . lOlx) used in carrier aggregation to group (330 / 430 / 510) a plurality of carrier components (101a... lOlx) used in carrier aggregation (310) into different subsets of carrier components (103 / 104 / 105), based on at least one common characteristic (320 / 410) associated with each respective plurality of carrier components {(101b... lOle), (10 Ij . . . 10 Ik), (101m... 101n){ that have been grouped into respective subsets of carrier components (103 / 104 / 105). At least one subset of carrier components (103) may include more than one carrier components (lOlb / lOlc) of at least one commoncharacteristic. The apparatus 720 may also be caused to receive (360 / 450 / 620) a declaration of radio link failure from the user equipment (203 / 213 / 402) upon determining that a failure of at least one carrier component (101b, lOlc / lOlj) is detected (340) in more than one of the respective subsets of carrier components (103 / 104).

[0062] In some exemplary embodiments, apparatuses 710 and / or 720 may also include or be coupled to one or more antennas 715 and 725 for receiving a downlink signal and for transmitting via an uplink from apparatus 710 and apparatus 720, respectively. Apparatuses 710 and / or 720 may further include transceivers 716 and 726, respectively, configured to transmit and receive information. The transceiver 716 and 726 may also include a radio interface that may correspond to a plurality of radio access technologies including one or more of GSM, LTE, LTE-A, 5G, NR, WLAN, NB-IoT, Bluetooth, BT-LE, NFC, RFID, UWB, or the like. The radio interface may include other components, such as filters, converters (for example, digital-to-analog converters or the like), symbol demappers, signal shaping components, an Inverse Fast Fourier Transform (IFFT) module, or the like, to process symbols, such as OFDMA symbols, carried by a downlink or an uplink.

[0063] For instance, transceivers 716 and 726 may be respectively configured to modulate information on to a carrier waveform for transmission and demodulate received information for further processing by other elements of apparatuses 710 and / or 720. In other example embodiments, transceivers 716 and 726 may be capable of transmitting and receiving signals or data directly. Additionally or alternatively, in some example embodiments, apparatuses 710 and / or 720 may include an input and / or output device (I / O device). In certain example embodiments, apparatuses 710 and / or 720 may further include a user interface, such as a graphical user interface or touchscreen.

[0064] In certain example embodiments, memory 714 and memory 724 store software modules that provide functionality when executed by processors 712 and 722, respectively. The modules may include, for example, an operating system that provides operating system functionality for apparatuses 710 and / or 720. The memorymay also store one or more functional modules, such as an application or program, to provide additional functionality for apparatuses 710 and / or 720. The components of apparatuses 710 and / or 720 may be implemented in hardware, or as any suitable combination of hardware and software. According to certain example embodiments, apparatus 710 may optionally be configured to communicate with apparatus 720 via a wireless or wired communications link 730 according to any radio access technology, such as NR.

[0065] According to certain example embodiments, processors 712 and 722, and memory 714 and 724 may be included in or may form a part of processing circuitry or control circuitry. In addition, in some example embodiments, transceivers 716 and 726 may be included in or may form a part of transceiving circuitry.

[0066] In some exemplary embodiments, an apparatus (e.g., apparatus 710 and / or apparatus 720) may include means for performing a method, a process, or any of the variants discussed herein. Examples of the means may include one or more processors, memory, controllers, transmitters, receivers, and / or computer program code for causing the performance of the operations.

[0067] Certain exemplary embodiments may be directed to an apparatus 710 that includes means for grouping (330 / 430 / 510) a plurality of carrier components (101a... lOlx) used in carrier aggregation (310) into different subsets of carrier components (103 / 104 / 105), based on at least one common characteristic (320 / 410) associated with each respective plurality of carrier components {(101b... lOle), (10 Ij . . . 10 Ik), (101m... 101n)} that have been grouped into respective subsets of carrier components (103 / 104 / 105). At least one subset of carrier components (103) may include more than one carrier components (101b, 101c) of at least one common characteristic. The apparatus 710 may also include means for declaring (360 / 440 / 520) a radio link failure, upon determining a failure of at least one carrier component (101b, lOlc / lOlj) is detected (340) in more than one of the respective subsets of carrier components (103 / 104).

[0068] Other exemplary embodiments may be directed to an apparatus 720 that includes means for configuring (610) a user equipment (203 / 213 / 402) for at least onecommon characteristic of a plurality of carrier components (101a. . . lOlx) used in carrier aggregation to group (330 / 430 / 510) a plurality of carrier components (101a... lOlx) used in carrier aggregation (310) into different subsets of carrier components (103 / 104 / 105), based on at least one common characteristic (320 / 410) associated with each respective plurality of carrier components {(101b... lOle), (10 Ij . . . 10 Ik), (101m... 101n)} that have been grouped into respective subsets of carrier components (103 / 104 / 105). At least one subset of carrier components (103) may include more than one carrier components (lOlb / lOlc) of at least one common characteristic. The apparatus 720 may also include means for receiving (360 / 450 / 620) a declaration of radio link failure from the user equipment (203 / 213 / 402) upon determining that a failure of at least one carrier component (101b, lOlc / lOlj) is detected (340) in more than one of the respective subsets of carrier components (103 / 104).

[0069] As used herein, the term “circuitry” may refer to hardware-only circuitry implementations (for example, analog and / or digital circuitry), combinations of hardware circuits and software, combinations of analog and / or digital hardware circuits with software / firmware, any portions of hardware processor(s) with software, including digital signal processors, that work together to cause an apparatus (for example, apparatus 710 and / or 720) to perform various functions, and / or hardware circuit(s) and / or processor(s), or portions thereof, that use software for operation but where the software may not be present when it is not needed for operation. As a further example, as used herein, the term “circuitry” may also cover an implementation of merely a hardware circuit or processor or multiple processors, or portion of a hardware circuit or processor, and the accompanying software and / or firmware. The term circuitry may also cover, for example, a baseband integrated circuit in a server, cellular network node or device, or other computing or network device.

[0070] A computer program product may include one or more computer-executable components which, when the program is run, are configured to carry out some example embodiments. The one or more computer-executable components may be atleast one software code or portions of it. Modifications and configurations required for implementing functionality of certain example embodiments may be performed as routine(s), which may be implemented as added or updated software routine(s). Software routine(s) may be downloaded into the apparatus.

[0071] As an example, software or a computer program code or portions of it may be in a source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, distribution medium, or computer readable medium, which may be any entity or device capable of carrying the program. Such carriers may include a record medium, computer memory, read-only memory, photoelectrical and / or electrical carrier signal, telecommunications signal, and software distribution package, for example. Depending on the processing power needed, the computer program may be executed in a single electronic digital computer or it may be distributed amongst a number of computers. The computer readable medium or computer readable storage medium may be a non-transitory medium.

[0072] In other example embodiments, the functionality may be performed by hardware or circuitry included in an apparatus (for example, apparatuses 710 and / or 720), for example through the use of 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 example embodiment, the functionality may be implemented as a signal, a non-tangible means that can be carried by an electromagnetic signal downloaded from the Internet or other network.

[0073] According to certain example embodiments, an apparatus, such as a node, device, or a corresponding component, may be configured as circuitry, a computer or a microprocessor, such as single-chip computer element, or as a chipset, including at least a memory for providing storage capacity used for arithmetic operation and an operation processor for executing the arithmetic operation.

[0074] The features, structures, or characteristics of example embodiments described throughout this specification may be combined in any suitable maimer in one or more example embodiments. For example, the usage of the phrases “certain embodiments,” “an example embodiment,” “some embodiments,” or other similar language,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, appearances of the phrases “in certain embodiments,” “an example embodiment,” “in some embodiments,” “in other embodiments,” or other similar language, throughout this specification do not necessarily refer to the same group of embodiments, and the described features, structures, or characteristics may be combined in any suitable manner in one or more example embodiments. Further, the terms “cell”, “node”, “gNB”, or other similar language throughout this specification may be used interchangeably.

[0075] As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or,” mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0076] One having ordinary skill in the art will readily understand that the disclosure as discussed above may be practiced with procedures in a different order, and / or with hardware elements in configurations which are different than those which are disclosed. Therefore, although the disclosure has been described based upon these example embodiments, it would be apparent to those of skill in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of example embodiments. Although the above embodiments refer to 5G NR and LTE technology, the above embodiments may also apply to any other present or future 3GPP technology, such as LTE-advanced, and / or fourth generation (4G) technology.

[0077] Partial Glossary:

[0078] 3 GPP 3rd Generation Partnership Project

[0079] 5G 5th Generation

[0080] CA Carrier Aggregation

[0081] CBR Channel Busy Ratio

[0082] DL Downlink

[0083] DTX Discontinuous Transmission

[0084] EMBB Enhanced Mobile Broadband

[0085] gNB 5G or Next Generation NodeB

[0086] LTE Long Term Evolution

[0087] MAC Medium Access Control

[0088] MCS Modulation and Coding Scheme

[0089] NR New Radio

[0090] RAN Radio Access Network

[0091] RedCap Reduced Capability

[0092] RF Radio Frequency

[0093] RLC Radio Link Control

[0094] RLF Radio Link Failure

[0095] RP Resource Pool

[0096] Rx Reception

[0097] SL Sidelink

[0098] Tx Transmission

[0099] UE User Equipment

[0100] UL Uplink

Claims

WE CLAIM:

1. An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: group a plurality of carrier components used in carrier aggregation into different subsets of carrier components, based on at least one common characteristic associated with each respective plurality of carrier components that have been grouped into respective subsets of carrier components, wherein at least one subset of carrier components includes more than one carrier components of at least one common characteristic; and declare a radio link failure, upon determining a failure of at least one carrier component is detected in more than one of the respective subsets of carrier components.

2. The apparatus according to claim 1, wherein the at least one common characteristic comprises one or more of: frequency band, transmission power, power spectral density, channel busy ratio, or radio link condition.

3. The apparatus according to claim 2, wherein the at least one common characteristic associated with each respective plurality of carrier components that comprise the respective subsets of carrier components being one or more of:(a) a frequency band, such that each of the different subsets of carrier components corresponds to a different frequency band;(b) a difference offset in transmission power between different carriers relative to a transmission power of a particular reference carrier component from among the plurality of carrier components, such that each of the different subsets of carrier components (103 / 104 / 105) corresponds to a specified difference offset in transmission power based on the particular reference carrier component;(c) a difference offset in power spectral density between different carriers relative to a power spectral density of a particular reference carrier component from among the plurality of carrier components, such that each of the different subsets of carrier components corresponds to a specified difference offset in power spectral density based on the particular reference carrier component;(d) a difference offset in measured channel busy ratio over a resource pool on each of the plurality of carrier components relative to a channel busy ratio over a resource pool on a particular reference carrier component, such that the measured channel busy ratio of carrier components in different subsets of carrier components corresponds to a specified difference offset in measured channel busy ratio based on the particular reference carrier component; or(e) a measured channel busy ratio of a particular reference carrier component from among the plurality of carrier components, such that each of the different subsets of the carrier components corresponds to a different measured channel busy ratio based on the particular reference carrier component.

4. The apparatus according to claim 3, wherein the difference offset in the transmission power or the power spectral density is based on one of: a power configuration for the resource pool on each of the plurality of carrier components; a maximum transmission power for the measured channel busy ratio over the resource pool on each of the plurality of carrier components; or being pre-configured for the apparatus for each of the plurality of carrier components.

5. The apparatus according to any one of claims 1-4, wherein the at least one memory and the instructions, when executed by the at least one processor, further cause the apparatus at least to: receive, from a network entity, a configuration or a pre-configuration comprising the at least one common characteristic of each of the plurality of carriercomponents.

6. The apparatus according to any one of claims 1-5, wherein: in a case of packet duplication being configured for a radio bearer transmitted by the apparatus, the radio link failure is declared when the failure is determined in at least one carrier component in each of the different subsets of carrier components that are used for the packet duplication for the radio bearer.

7. The apparatus according to any one of claims 1-6, wherein the at least one memory and the instructions, when executed by the at least one processor, further cause the apparatus at least to: transmit an indication to the network entity that the radio link failure is declared.

8. The apparatus according to any one of claims 1-7, wherein the at least one memory and the instructions, when executed by the at least one processor, further cause the apparatus at least to: transmit an indication from an access stratum layer to a non-access stratum layer locally at the apparatus that the radio link failure is declared.

9. An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: configure a user equipment for at least one common characteristic of a plurality of carrier components used in carrier aggregation to group a plurality of carrier components used in carrier aggregation into different subsets of carrier components, based on at least one common characteristic associated with each respective plurality of carrier components that have been grouped into respective subsets of carrier components, wherein at least one subset of carrier componentsincludes more than one carrier components of at least one common characteristic; and receive a declaration of radio link failure from the user equipment upon determining that a failure of at least one carrier component is detected in more than one of the respective subsets of carrier components.

10. The apparatus according to claim 9, wherein the at least one common characteristic comprises one or more of: frequency band, transmission power, power spectral density, channel busy ratio, or radio link condition.

11. The apparatus according to claim 9 or claim 10, wherein the at least one common characteristic is configured for the user equipment using a system information block or radio resource control message.

12. The apparatus according to any one of claims 9-11, wherein the at least one common characteristic associated with each respective plurality of carrier components that comprise the respective subsets of carrier components being one or more of:(a) a frequency band, such that each of the different subsets of carrier components corresponds to a different frequency band;(b) a difference offset in transmission power between different carriers relative to a transmission power of a particular reference carrier component from among the plurality of carrier components, such that each of the different subsets of carrier components corresponds to a specified difference offset in transmission power based on the particular reference carrier component;(c) a difference offset in power spectral density between different carriers relative to a power spectral density of a particular reference carrier component from among the plurality of carrier components, such that each of the different subsets of carrier components corresponds to a specified difference offset in power spectral density based on the particular reference carrier component;(d) a difference offset in measured channel busy ratio over a resource pool on each of the plurality of carrier components relative to a channel busy ratio over a resource pool on a particular reference carrier component, such that the measured channel busy ratio of carrier components in different subsets of carrier components of carrier components corresponds to a specified difference offset in measured channel busy ratio based on the particular reference carrier component; or(e) a measured channel busy ratio of a particular reference carrier component from among the plurality of carrier components, such that each of the different subsets of the carrier components corresponds to a different measured channel busy ratio based on the particular reference carrier component.

13. The apparatus according to claim 12, wherein the difference offset in the transmission power or the power spectral density is based on one of: a power configuration for the resource pool on each of the respective groups of carrier components; a maximum transmission power for the measured channel busy ratio over the resource pool on each of the respective groups of carrier components; or being pre-configured for the apparatus for each of the respective groups of carrier components.

14. The apparatus according to any one of claims 9-13, wherein the at least one memory and the instructions, when executed by the at least one processor, further cause the apparatus at least to: perform a procedure to recover the radio link failure or release a connection with the user equipment to resolve the radio link failure.

15. The apparatus according to any one of claims 9-14, wherein the at least one memory and the instructions, when executed by the at least one processor, further cause the apparatus at least to: transmit, to the user equipment, a configuration or a pre-configurationcomprising the at least one common characteristic of each of the respective groups of carrier components.

16. An apparatus comprising: means for grouping a plurality of carrier components used in carrier aggregation into different subsets of carrier components, based on at least one common characteristic associated with each respective plurality of carrier components that have been grouped into respective subsets of carrier components, wherein at least one subset of carrier components includes more than one carrier components of at least one common characteristic; and means for declaring a radio link failure, upon determining a failure of at least one carrier component is detected in more than one of the respective subsets of carrier components.

17. The apparatus according to claim 16, wherein the at least one common characteristic comprises one or more of: frequency band, transmission power, power spectral density, channel busy ratio, or radio link condition.

18. The apparatus according to claim 17, wherein the at least one common characteristic associated with each respective plurality of carrier components that comprise the respective subsets of carrier components being one or more of:(a) a frequency band, such that each of the different subsets of carrier components corresponds to a different frequency band;(b) a difference offset in transmission power between different carriers relative to a transmission power of a particular reference carrier component from among the plurality of carrier components, such that each of the different subsets of carrier components corresponds to a specified difference offset in transmission power based on the particular reference carrier component;(c) a difference offset in power spectral density between different carriers relative to a power spectral density of a particular reference carrier component fromamong the plurality of carrier components, such that each of the different subsets of carrier components corresponds to a specified difference offset in power spectral density based on the particular reference carrier component;(d) a difference offset in measured channel busy ratio over a resource pool on each of the plurality of carrier components relative to a channel busy ratio over a resource pool on a particular reference carrier component, such that the measured channel busy ratio of carrier components in different subsets of carrier components corresponds to a specified difference offset in measured channel busy ratio based on the particular reference carrier component; or(e) a measured channel busy ratio of a particular reference carrier component from among the plurality of carrier components, such that each of the different subsets of the carrier components corresponds to a different measured channel busy ratio based on the particular reference carrier component.

19. The apparatus according to claim 18, wherein the difference offset in the transmission power or the power spectral density is based on one of: a power configuration for the resource pool on each of the plurality of carrier components; a maximum transmission power for the measured channel busy ratio over the resource pool on each of the plurality of carrier components; or being pre-configured for the apparatus for each of the plurality of carrier components.

20. The apparatus according to any one of claims 16-19, further comprising: means for receiving, from a network entity, a configuration or a preconfiguration comprising the at least one common characteristic of each of the plurality of carrier components.

21. The apparatus according to any one of claims 16-20, wherein: in a case of packet duplication being configured for a radio bearertransmitted by the apparatus, the radio link failure is declared when the failure is determined in at least one carrier component in each of the different subsets of carrier components that are used for the packet duplication for the radio bearer.

22. The apparatus according to any one of claims 16-21, further comprising: means for transmitting an indication to the network entity that the radio link failure is declared.

23. The apparatus according to any one of claims 16-22, further comprising: means for transmitting an indication from an access stratum layer to a non- access stratum layer locally at the apparatus that the radio link failure is declared.

24. An apparatus comprising: means for configuring a user equipment for at least one common characteristic of a plurality of carrier components used in carrier aggregation to group a plurality of carrier components used in carrier aggregation into different subsets of carrier components, based on at least one common characteristic associated with each respective plurality of carrier components that have been grouped into respective subsets of carrier components, wherein at least one subset of carrier components includes more than one carrier components of at least one common characteristic; and means for receiving a declaration of radio link failure from the user equipment upon determining that a failure of at least one carrier component is detected in more than one of the respective subsets of carrier components.

25. The apparatus according to claim 24, wherein the at least one common characteristic comprises one or more of: frequency band, transmission power, power spectral density, channel busy ratio, or radio link condition.

26. The apparatus according to claim 24 or claim 25, wherein the at least onecommon characteristic is configured for the user equipment using a system information block or radio resource control message.

27. The apparatus according to any one of claims 24-26, wherein the at least one common characteristic associated with each respective plurality of carrier components that comprise the respective subsets of carrier components being one or more of:(a) a frequency band, such that each of the different subsets of carrier components corresponds to a different frequency band;(b) a difference offset in transmission power between different carriers relative to a transmission power of a particular reference carrier component from among the plurality of carrier components, such that each of the different subsets of carrier components corresponds to a specified difference offset in transmission power based on the particular reference carrier component;(c) a difference offset in power spectral density between different carriers relative to a power spectral density of a particular reference carrier component from among the plurality of carrier components, such that each of the different subsets of carrier components corresponds to a specified difference offset in power spectral density based on the particular reference carrier component;(d) a difference offset in measured channel busy ratio over a resource pool on each of the plurality of carrier components relative to a channel busy ratio over a resource pool on a particular reference carrier component, such that the measured channel busy ratio of carrier components in different subsets of carrier components of carrier components corresponds to a specified difference offset in measured channel busy ratio based on the particular reference carrier component; or(e) a measured channel busy ratio of a particular reference carrier component from among the plurality of carrier components, such that each of the different subsets of the carrier components corresponds to a different measured channel busy ratio based on the particular reference carrier component.

28. The apparatus according to claim 27, wherein the difference offset in the transmission power or the power spectral density is based on one of: a power configuration for the resource pool on each of the respective groups of carrier components; a maximum transmission power for the measured channel busy ratio over the resource pool on each of the respective groups of carrier components; or being pre-configured for the apparatus for each of the respective groups of carrier components.

29. The apparatus according to any one of claims 24-28, further comprising: means for performing a procedure to recover the radio link failure or release a connection with the user equipment to resolve the radio link failure.

30. The apparatus according to any one of claims 24-29, further comprising: means for transmitting, to the user equipment, a configuration or a pre- configuration comprising the at least one common characteristic of each of the respective groups of carrier components.

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