Sidelink carrier aggregation for wireless communication networks

Abstract

Systems, methods, processors, and circuitries are provided for configuring sidelink (SL) communications for carrier aggregation (CA). In some aspects, a baseband processor is configured to perform operations including receiving, at a user equipment (UE) from a peer UE, an indication whether the peer UE supports SL CA; and generating, for the peer UE, based on the peer UE supporting SL CA, an SL reconfiguration message configuring an SL data radio bearer (SL-DRB) to carry data from the UE to the peer UE.

Description

SIDELINK CARRIER AGGREGATION FOR WIRELESS COMMUNICATION NETWORKSREFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 518,770, filed on August 10, 2023, the contents of which are hereby incorporated herein by reference in their entirety.FIELD

[0002] This disclosure relates to sidelink (SL) techniques for wireless communication networks.BACKGROUND

[0003] Wireless communication networks and wireless communication services are becoming increasingly dynamic, complex, and ubiquitous. For example, some wireless communication networks may be developed to implement Fifth- Generation (5G) or New Radio (NR) technology, Sixth-Generation (6G) technology, and so on. Such technology may include solutions for enabling user equipment (UE) and network devices, such as base stations, to communicate with one another. A feature of such networks and devices may include SL communications, which are direct communications between two UEs.BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The present disclosure will be readily understood and enabled by the detailed description and accompanying figures of the drawings. Like reference numerals may designate like features and structural elements. Figures and corresponding descriptions are provided as non-limiting examples of aspects, implementations, etc., of the present disclosure, and references to "an" or “one” aspect, implementation, etc., may not necessarily refer to the same aspect, implementation, etc., and may mean at least one, one or more, etc.

[0005] FIG. 1 is a diagram of an example wireless network, according to various aspects of the present disclosure.

[0006] FIG. 2 is a message flow diagram illustrating messaging between a transmitting UE (TX UE) and a receiving UE (RX UE) to support SL communications therebetween, according to various aspects of the present disclosure.

[0007] FIG. 3 is another message flow diagram illustrating messaging between a TX UE andan RX UE to support SL communication therebetween, according to various aspects of the present disclosure.

[0008] FIG. 4 illustrates layers of a TX UE operating to configure a single component carrier (CC) for SL signal radio bearers (SRBs) used for SL communication with an RX UE, according to various aspects of the present disclosure.

[0009] FIG. 5 illustrates layers of a TX UE operating to configure multiple CCs for SL- SRBs used for SL communication with an RX UE, according to various aspects of the present disclosure.

[0010] FIG. 6 is a flow diagram outlining an example method for declaring a radio link failure (RLF) during SL communication, according to various aspects of the present disclosure.

[0011] FIG. 7 is a flow diagram outlining another example method for declaring an RLF during SL communication, according to various aspects of the present disclosure.

[0012] FIGS. 8 A and 8B are a flow diagram outlining yet another example method for declaring an RLF during SL communication, according to various aspects described.

[0013] FIG. 9 is a flow diagram outlining yet another example method for declaring an RLF during SL communication, according to various aspects of the present disclosure.

[0014] FIG. 10 is a flow diagram outlining an example method for employing a threshold number of carriers to determine whether to declare an RLF for an RX UE, according to various aspects of the present disclosure.

[0015] FIG. 11 is a diagram of an example of components of a device according to various aspects of the present disclosure.DETAILED DESCRIPTION

[0016] The following detailed description refers to the accompanying drawings. Like reference numbers in different drawings may identify the same or similar features, elements, operations, etc. Additionally, the present disclosure is not limited to the following description as other implementations may be utilized, and structural or logical changes made, without departing from the scope of the present disclosure.

[0017] Communication in a wireless network may include downlink (DL) from a radio access network (RAN) node to a user equipment (UE), uplink (UL) from a UE to a RAN node, and sidelink (SL) communication between two peer UEs without directing the communication through a RAN node. One of several use cases for SL communication between UEs is Vehicle- to-Everything (V2X) communication, by which a vehicle may communicate with other vehicles, as well as other communicative elements (e.g., to facilitate autonomous transportation, enhancetransportation safety, and so on). The interface facilitating such SL communication between UEs is often referred to as PC5.

[0018] Within ongoing 3GPP (Third-Generation Partnership Project) standardization work, an effort has been made to support Fifth-Generation (5G) or New Radio (NR) SL carrier aggregation (CA) operation based on Fourth-Generation (4G) or Long-Term Evolution (LTE) SL CA operation. Generally, such work presumes that only aspects of LTE SL CA design (e.g., those aspects related to SL carrier selection and reselection, synchronization of aggregated carriers, transmitting power split for simultaneous SL transmission, and packet duplication) are to be reused for NR sidelink CA operations.

[0019] Generally, CA operations involve the concurrent use of multiple CCs to provide greater transmission bandwidth and / or enhance reliability via packet duplication. For example, in LTE, DL CA operations involve the use of a single primary CC (PCC) and one or more secondary CCs (SCCs). A PCC may carry both data and control signaling, while each SCC carries only data. However, LTE SL operations exhibit characteristics that do not facilitate the use of PCC / SCC design employed in DL CA operation. Such characteristics include, for example, an absence of Radio Resource Control (RRC) connectivity in the PC5 interface, a lack of SL unicast operations, a lack of Hybrid Automatic Repeat Request (HARQ) feedback, and service-identifier-to-carrier mapping being provided by an upper layer (e.g., the V2X layer) and not configured in an Access Stratum (AS) layer.

[0020] Moreover, while the 3GPP System Aspects Working Group 2 (SA2) has leveraged the use in LTE SL operations of the V2X layer to provide mapping from a V2X service identifier associated with multiple CCs to a Layer 2 (L2) destination address, the RAN working groups (WGs) assume that NR SL operations employ a single CC.

[0021] As is discussed in greater detail below, some aspects of the present disclosure facilitate NR sidelink unicast transmissions that employ carrier aggregation by way of using upper layer (e.g., V2X layer) mapping of a service ID to multiple CCs while not relying upon PCC / SCC differentiation. In some aspects, a transmitting UE may employ the multiple CCs for SL unicast transmission to a receiving UE for one or more SL data radio bearers (SL-DRBs) and / or an SL signal radio bearer (one or more selective SL-SRBs, such as SL-SRB3) to improve the performance and / or reliability of the SL connection. For example, the transmitting UE may request and receive SL capability information from the receiving UE, with such information including whether the receiving UE supports SL CA. In response, the transmitting UE may configure the receiving UE with one or more CCs for subsequent transmissions (e.g., over one or more SL-DRBs and / or SL-SRB3) to the receiving UE.

[0022] Further, in some aspects of the present disclosure, lower layers of the transmitting UE may handle at least certain aspects of Radio Link Monitoring (RLM) and associated Radio Link Failure (RLF) processing (e.g., based on HARQ feedback from the receiving UE and / or RLC retransmissions to the receiving UE). In some aspects, the RLM and RLF processing may be performed independently in some or all carriers of the SL-DRBs and / or SL-SRB3, or on a per- destination (e.g., per-receiving-UE) basis. Also, in some aspects, the transmitting UE may reconfigure the carriers employed for CA and / or duplication as part of the RLM / RLF process (e.g., in response to the detection of errors on one or more CCs), thus further enhancing the performance and / or reliability of the SL connection in an efficient manner, possibly without involving the upper layers of the transmitting UE.

[0023] FIG. 1 is an example network 100 according to one or more implementations described herein. Example network 100 may include UEs 1 10-1 , 1 10-2, etc. (referred to collectively as “UEs 110” and individually as “UE 110”), a radio access network (RAN) 120, a core network (CN) 130, application servers 140, and external networks 150.

[0024] The systems and devices of example network 100 may operate in accordance with one or more communication standards, such as Second- Generation (2G), Third- Generation (3G), Fourth-Generation (4G) (e.g., Long-Term Evolution (LTE)), and / or Fifth-Generation (5G) (e.g., New Radio (NR)) communication standards of the Third-Generation Partnership Project (3GPP). Additionally, or alternatively, one or more of the systems and devices of example network 100 may operate in accordance with other communication standards and protocols discussed herein, including future versions or generations of 3GPP standards (e.g., Sixth- Generation (6G) standards, Seventh-Generation (7G) standards, etc.), Institute of Electrical and Electronics Engineers (IEEE) standards (e.g., Wireless Metropolitan Area Network (WMAN), Worldwide Interoperability for Microwave Access (WiMAX), etc.), and more.

[0025] As shown, UEs 110 may include smartphones (e.g., handheld touchscreen mobile computing devices connectable to one or more wireless communication networks). Additionally, or alternatively, UEs 110 may include other types of mobile or non- mobile computing devices capable of wireless communications, such as personal data assistants (PDAs), pagers, laptop computers, desktop computers, wireless handsets, smartwatches, etc. In some implementations, UEs 110 may include internet of things (loT) devices (or loT UEs) that may include a network access layer designed for low-power loT applications utilizing short-lived UE connections. Additionally, or alternatively, an loT UE may utilize one or more types of technologies, such as machine-to-machine (M2M) communications or machine-type communications (MTC) (e.g., to exchanging data with an MTC server or other device via a public land mobile network(PLMN)), proximity-based service (ProSe) or device-to-device (D2D) communications, sensor networks, loT networks, and more. Depending on the scenario, an M2M or MTC exchange of data may be a machine-initiated exchange, and an loT network may include interconnecting loT UEs (which may include uniquely identifiable embedded computing devices within an Internet infrastructure) with short-lived connections. In some scenarios, loT UEs may execute background applications (e.g., keep-alive messages, status updates, etc.) to facilitate the connections of the loT network.

[0026] The connection may include an M2M connection, MTC connection, D2D connection, SL connection, etc. The connection may involve a PC5 interface. In some implementations, UEs 110 may be configured to discover one another, negotiate wireless resources between one another, and establish connections between one another, without intervention or communications involving RAN node 122 or another type of network node. In some implementations, discovery, authentication, resource negotiation, registration, etc., may involve communications with RAN node 122 or another type of network node.

[0027] UEs 110 may use one or more wireless (e.g., sidelink (SL)) connections 112 to communicate with one another. As described herein, UE 110-1 may communicate with RAN node 122 to request SL resources. RAN node 122 may respond to the request by providing UE 110 with a dynamic grant (DG) or configured grant (CG) regarding SL resources. A DG may involve a grant based on a grant request from UE 110. A CG may involve a resource grant without a grant request and may be based on a type of service being provided (e.g., services that have strict timing or latency requirements). UE 1 10 may perform a clear channel assessment (CCA) procedure based on the DG or CG, select SL resources based on the CCA procedure and the DG or CG; and communicate with another (e.g., peer) UE 110 based on the SL resources. The UE 110 may communicate with RAN node 122 using a licensed frequency band and communicate with the other UE 110 using an unlicensed frequency band. In some examples, one UE 110 (e.g., UE 110-1) may be a transmitting UE (TX UE), and the other UE (e.g., UE 110-2) may be a receiving UE (RX UE).

[0028] UEs 110 may communicate and establish a connection (e.g., be communicatively coupled) with RAN 120, which may involve one or more wireless channels 1 14-1 and 114-2, each of which may include a physical communications interface / layer.

[0029] A PC5 Quality of Service (QoS) identifier (PQI) may be determined and used to indicate a QoS associated with a Sidelink at Unlicensed Band (SL-U) communication (e.g., a channel, data flow, etc.). Similarly, a Layer 1 (LI) priority value may be determined and used to indicate a priority of an SL-U transmission, SL-U channel, SL-U data, etc. The PQI and / or LIpriority value may be mapped to a Channel Access Priority Class (CAPC) value, and the PQI, LI priority, and / or CAPC may indicate SL channel occupancy time (COT) sharing, maximum COT (MCOT), timing gaps for COT sharing, Listen Before Talk (LBT) configuration, traffic and channel priorities, and more.

[0030] As shown, UE 110 may also, or alternatively, connect to access point (AP) 116 via connection interface 118, which may include an air interface enabling UE 110 to communicatively couple with AP 116. AP 1 16 may include a wireless local area network (WLAN), WLAN node, WLAN termination point, etc. The connection interface 118 may include a local wireless connection, such as a connection consistent with any IEEE 702.11 protocol, and AP 116 may include a wireless fidelity router or other AP. While not explicitly depicted in FIG. 1, AP 116 may be connected to another network (e.g., the Internet) without connecting to RAN 120 or CN 130.

[0031] RAN 120 may include one or more RAN nodes 122-1 and 122-2 (referred to collectively as RAN nodes 122, and individually as RAN node 122) that enable channels 114-1 and 114-2 to be established between UEs 110 and RAN 120. RAN nodes 122 may include network access points configured to provide radio baseband functions for data and / or voice connectivity between users and the network based on one or more of the communication technologies described herein (e.g., 2G, 3G, 4G, 5G, WiFi, etc.). As examples, therefore, a RAN node may be an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node B (e.g., an enhanced Node B, eNodeB, eNB, 4G base station, etc.), a next-generation base station (e.g., a 5G base station, NR base station, next-generation eNBs (gNB), etc.). RAN nodes 122 may include a roadside unit (RSU), a transmission reception point (TRxP or TRP), and one or more other types of ground stations (e.g., terrestrial access points). In some scenarios, RAN node 122 may be a dedicated physical device, such as a macrocell base station, and / or a low power (LP) base station for providing femtocells, picocells, or the like having smaller coverage areas, smaller user capacity, or higher bandwidth compared to macrocells. Additionally, or alternatively, one or more of RAN nodes 122 can be next generation eNBs (i.e., gNBs) that can provide E-UTRA user plane and control plane protocol terminations 126, 128 toward UEs 110, and that can be connected to a 5G core network (5GC) 130 via an NG interface 124.

[0032] Any of the RAN nodes 122 can terminate an air interface protocol and can be the first point of contact for UEs 110. In some implementations, any of the RAN nodes 122 can fulfill various logical functions for the RAN 120, including, but not limited to, radio network controller (RNC) functions, such as radio bearer management, uplink and downlink dynamic radio resource management and data packet scheduling, and mobility management. UEs 110 canbe configured to communicate using orthogonal frequency-division multiplexing (OFDM) communication signals with each other or with any of the RAN nodes 122 over a multicarrier communication channel in accordance with various communication techniques, such as, but not limited to, an orthogonal frequency-division multiple-access (OFDMA) communication technique (e.g., for downlink communications) or a single-carrier frequency-division multipleaccess (SC-FDMA) communication technique (e.g., for uplink and ProSe or sidelink (SL) communications), although the scope of such implementations is not necessarily limited in this regard. The OFDM signals can include a plurality of orthogonal subcarriers.

[0033] In some implementations, a downlink resource grid may be used for downlink transmissions from any of the RAN nodes 122 to UEs 110, and uplink transmissions may utilize similar techniques. The grid may be a time- frequency grid (e.g., a resource grid or timefrequency resource grid) that represents the physical resource for downlink in each slot. Such a time- frequency plane representation is a common practice for OFDM systems, which makes it intuitive for radio resource allocation. Each column and each row of the resource grid corresponds to one OFDM symbol and one OFDM subcarrier, respectively. The duration of the resource grid in the time domain corresponds to one slot in a radio frame. The smallest timefrequency unit in a resource grid is denoted as a resource element (RE). Each resource grid includes resource blocks (RBs), which describe the mapping of certain physical channels to resource elements. Each RB may include a collection of REs; in the frequency domain, this may represent the smallest quantity of resources that currently may be allocated. There are several different physical downlink channels that are conveyed using such RBs.

[0034] The RAN nodes 122 may be configured to communicate with one another via interface 123. In implementations where the system is an LTE system, interface 123 may be an X2 interface. In NR systems, interface 123 may be an Xn interface. The X2 interface may be defined between two or more RAN nodes 122 (e.g., two or more eNBs / gNBs or a combination thereof) that connect to Evolved Packet Core (EPC) or CN 130, or between two eNBs connecting to an EPC.

[0035] CN 130 may include a plurality of network elements 132, which are configured to offer various data and telecommunications services to customers / subscribers (e.g., users of UEs 1 10) who are connected to the CN 130 via the RAN 120. In some implementations, CN 130 may include an EPC, a 5G CN, and / or one or more additional or alternative types of CNs. The components of the CN 130 may be implemented in one physical node or separate physical nodes including components to read and execute instructions from a machine-readable or computer- readable medium (e.g., a non-transitory machine-readable storage medium).

[0036] As shown, CN 130, application servers 140, and external networks 150 may be connected to one another via interfaces 134, 136, and 138, which may include IP network interfaces.

[0037] FIG. 2 is a message flow diagram illustrating messaging 200 between a transmitting UE (TX UE, such as UE 110-1) and a receiving UE (RX UE, such as UE 110-2) to support SL communications therebetween (e.g., over SL connection 112 of FIG. 1), according to various aspects of the present disclosure. As illustrated in FIG. 2, the TX UE may receive a capability message 202 from the RX UE that indicates to the TX UE that the RX UE supports SL carrier aggregation (CA). In response to the capability message 202, the TX UE may transmit an SL reconfiguration message 204 to the RX UE. In some aspects, the SL reconfiguration message 204 may configure an SL data radio bearer (SL-DRB) for packet duplication or for SL CA with a plurality of SL component carriers (CCs) to carry data from the TX UE to the RX UE. In some aspects of the present disclosure, the capability message 202 and the SL reconfiguration message 204 may be carried on an SL signal radio bearer (SRB) (e.g., SL-SRB3), as described in greater detail below.

[0038] FIG. 3 is another message flow diagram illustrating messaging 300 between a TX UE (e.g., UE 110-1) and an RX UE (e.g., UE 110-2) to support SL communication therebetween, according to various aspects of the present disclosure. As depicted in FIG. 3, the TX UE and the RX UE determine which one or more CCs are to be used to perform the messaging operations to follow.

[0039] Prior to the exchanging of messages between the TX UE and the RX UE (e.g., to create an SL connection between the TX UE and the RX UE), the TX UE and the RX UE may first perform a first CC selection 302, during which one or more CCs are selected to carry initial communications therebetween to create an SL connection (e.g., SL connection 112 of FIG. 1). In some aspects, the first CC selection 302 may occur at an upper layer (e.g., a V2X layer) of the communication system (e.g., network 100 of FIG. 1). For example, an upper (e.g., V2X) layer of both the TX UE and the RX UE may communicate with an application server 140 (e.g., a V2X application server) by way of RAN 120 and CN 130 (as illustrated in FIG. 1) to perform the first CC selection 302.

[0040] FIG. 4 illustrates layers of the TX UE operating to configure a single component carrier (CC) for SL signal radio bearers (SL-SRBs) used for SL communication with the RX UE, according to various aspects of the present disclosure. While an (upper) V2X layer 410 and a Media Access Control (MAC) layer 420 are depicted in FIG. 4 (as well as in FIG. 5, described below), other layers, such as a physical (PHY) layer, may also be present but are not explicitlyshown.

[0041] At the V2X layer 410, a service identifier (e.g., a V2X service identifier) to destination address mapping 412 and a service identifier to frequency mapping 414 (e.g., carrier determination for SL-SRBO, SL-SRB1, SL-SRB2, and initially SL-SRB3) may be performed. In some aspects, the destination address mapping 412 may map a V2X service identifier to a Layer-2 (L2) identifier pair (e.g., a source L2 identifier associated with the TX UE and a target L2 identifier associated with the RX UE). Also, in aspects associated with FIG. 4, the service identifier is mapped to a single frequency fi associated with a single CC, thus preventing the use of packet duplication of SL-SRBO, SL-SRB1, or SL-SRB2. The destination address mapping 412 and the frequency mapping 414 may both be passed to the MAC layer 420, which may then perform MAC scheduling 422 to transfer messages (e.g., messages 304-314, 318, and 320 of FIG. 3, described below, associated with SL-SRBO, SL-SRB1 , SL-SRB2, and initially SL- SRB3) over the single CC associated with single frequency fi.

[0042] In some aspects, the assignment of the single frequency fi may occur in a number of ways. In some examples, the V2X layer 410 may newly identify the single frequency fi. In other examples, the V2X layer may instead reuse the anchor carrier previously employed for SL Synchronization Signal (SLSS) transmission. In yet other examples, the V2X layer 410 may introduce a new anchor carrier (e.g., different from the anchor carrier for the SLSS), which may be specified in a System Information Block (SIB) received at TX UE from RAN 120 of FIG. 1. In additional examples, the V2X layer may reuse a frequency specified in an information element (IE) SL-C«n zgComm / inN7?->sl-FreqInfoList-rl6 provided in an SIB with the restriction of a single carrier / list number equaling one (e.g., for possible backward compatibility to 3GPP Rel- 16 / 17). Others processes by which the single frequency fi may be determined are possible in other aspects.

[0043] In other aspects of the present disclosure, FIG. 5 illustrates layers of the TX UE operating to configure multiple CCs for SL-SRBs used for SL communication with the RX UE. At the V2X layer 410, the service identifier (e.g., a V2X service identifier) to destination address mapping 412 and the service identifier to frequency mapping 414 (e.g., carrier determination for SL-SRBO, SL-SRB1, SL-SRB2, and initially SL-SRB3) may be performed. As noted above in conjunction with FIG. 3, in some aspects, the destination address mapping 412 may map a V2X service identifier to a Layer-2 (L2) identifier pair (e.g., a source L2 identifier associated with the TX UE and a target L2 identifier associated with the RX UE). In aspects associated with FIG. 5, the service identifier is mapped to multiple frequencies fi, t'2, and L. More specifically, in a particular aspect, frequency fi is mapped for both SL-SRBO and SL-SRB 1, and frequencies f?and fa are mapped for SL-SRB2 (e.g., thus facilitating packet duplication over both frequency fa and frequency fa). The destination address mapping 412 and the frequency mapping 414 may both be passed to the MAC layer 420, which may then perform MAC scheduling 422 to transfer messages (e.g., messages 304-314, 318, and 320 of FIG. 3, described below) over the multiple CCs associated with frequencies f i , 13, and fa according to their associations with SL-SRBO, SL- SRB1, and SL-SRB2.

[0044] Further, in other aspects, the initial use of SL-SRB3 (e.g., for exchange of messages 312, 314, 318, and 320 of FIG. 3 with the RX UE) may be carried over any of the one or more multiple frequencies fi, fa, and fa. In some aspects, SL-SRB3 may use the same mapping as one of SL-SRBO, SL-SRB 1, or SL-SRB2 (e.g., a single-frequency mapping with no duplication, or a multiple-frequency mapping with duplication). In other aspects, SL-SRB3 may employ a singlefrequency or multiple-frequency mapping that is different from any of SL-SRBO, SL-SRB 1 , and SL-SRB2.

[0045] Returning to FIG. 3, after the first CC selection 302 for SL-SRBO, SL-SRB 1, SL- SRB2, and the initial selection for SL-SRB3, a series of messages 304-310 may be exchanged between the TX UE and the RX UE (e.g., to establish an SL communication connection therebetween). In some aspects, the messages 304-310 may be PC5 (LTE-V2X) Signaling Protocol Stack (PC5-S) messages for control plane signaling over the PC5 interface to establish, maintain, and / or release a secure direct SL connection between the TX UE and the RX UE. Further, in some aspects, the messages 304-310 may include a Direct Communication Request (DCR) message 304 over SL-SRBO; a Direct Security Mode Command message 306 over SL- SRB 1 ; a Direct Security Mode Complete message 308, also over SL-SRB 1 ; and a Direct Communication Accept (DCA) message 310 over SL-SRB2. In other aspects, exchanges of other messages may be employed to create an SL connection between the TX UE and the RX UE.

[0046] After the creation of the SL connection, the TX UE may begin a process of selecting one or more CCs for transmitting data over the SL connection. In some aspects, the TX UE may transmit an SL capability enquiry message 312 that requests one or more capabilities of the RX UE, including whether the RX UE supports the use of SL CA in receiving data from the TX UE over multiple CCs. In response to the SL capability enquiry message 312, the RX UE may transmit an SL capability information message 314 that at least includes an indication as to whether the RX UE supports the use of SL CA. In some aspects, the SL capability enquiry message 312 and the SL capability information message 314 may be PC5-RRC messages that provide RRC-like functionality between the TX UE and the RX UE, and may include one ormore information elements (IES). In such aspects, the SL capability enquiry message 312 may be a CapabilityEnquirySidelink message, and the SL capability information message 314 may be a CapabilitylnformationSidelink message.

[0047] Based on whether the RX UE supports the use of SL CA, the TX UE may perform a second CC selection 316 to select one or more CCs for subsequent signaling transmissions over SL-SRB3 and / or for data transmissions over one or more SL Data Radio Bearers (SL-DRBs). In some aspects, in response to the SL capability information message 314 indicating that the RX UE does not support SL CA, the TX UE may select a single carrier (e.g., one of the same one or more carriers previously employed for SL-SRBO, SL-SRB1, SL-SRB2, and / or SL-SRB3) for carrying subsequent signals over SL-SRB3 and / or an SL-DRB.

[0048] If, instead, the RX UE supports the use of SL CA, the TX UE may configure the SL- SRB3 and / or one or more SL-DRBs with multiple CCs, with each of the SL-SRB3 and the one or more SL-DRBs being associated with a set of CCs (e.g., as provided earlier by the V2X layer). In some aspects, the second CC selection 316 of multiple CCs may be based on a Channel Busy Ratio (CBR) associated with CCs that are available for selection. Further, in some aspects, the CBR may be evaluated relative to a ProSe Per-Packet Priority (PPPP) associated with the SL messages that are to be transmitted.

[0049] In some aspects, the TX UE may transmit an SL reconfiguration message 318 over SL-SRB3 (e.g., a PC5-RRC message, such as an RRCReconfigurationSidelink message) that informs the RX UE which CCs will carry SL-SRB3 and the one or more SL-DRBs. In FIG. 3, for example, the TX UE configures the SL-SRB3 with a first CC set 322 with duplication, an SL-DRB 1 with a second CC set 324 with duplication, and an SL-DRB2 with the second CC set 324 with CA. In some aspects, the TX UE may configure the SL-SRB3 and / or one or more SL- DRBs for packet duplication based on whether a ProSe Per-Packet Reliability (PPPR) associated with packets carried over the corresponding radio bearer exceeds a predefined or configured PPPR threshold. In some aspects, the SL-SRB3 may be configured with a multiple-CC set for duplication, or a single CC. Also, in some aspects, the TX UE may configure greater or fewer numbers of SL-DRBs with the different or same CC sets individually, and may configure each CC set individually for CA or duplication. Also, in some aspects, the TX UE may configure all available CCs for CA for the one or more SL-DRBs, or may select a subset of the available CCs for CA for the one or more SL-DRBs to reduce power consumption at the TX UE and / or the RX UE.

[0050] In some aspects, in response to receiving the SL reconfiguration message 318, the RX UE may transmit an SL reconfiguration complete message 320 over SL-SRB3 (e.g., a PC5-RRC message, such as an RRCReconfigurationCompleteSidelink message), thus confirming the configuration of SL-SRB3 and the one or more SL-DRBs specified in the SL reconfiguration message 318. In response to the SL reconfiguration complete message 320, the TX UE may regard the multiple-CC configuration in SL reconfiguration message 318 as activated, and transmit signals over SL-SRB3 and data over the one or more SL-DRBs using the selected CC sets 322 and 324, as described above. Further, in some aspects, the TX UE may report to the network (e.g., by transmitting to a base station to which the TX UE is connected, such as a RAN node 122 of FIG. 1) at least some of the duplication / CA configuration negotiated with the RX UE (e.g., the target or destination L2 identifier associated with the RX UE, an indication of an SL-SRB3 and / or SL-DRB identifier, configured CC set(s) 322 and / or 324 associated with the identifier(s), and an indication of whether duplication or CA is associated with each carrier set(s) 322 and / or 324) (e.g., by way of an RRC Sidelink UE Information (SUI) message).

[0051] Consequently, as discussed above regarding various aspects of the present disclosure, the TX UE and the RX UE may directly communicate using SL unicast CA without referencing primary or secondary CCs.

[0052] After the TX UE configures CCs for the subsequent SL-SRB3 and one or more SL- DRBs, the TX UE may perform Radio Link Monitoring (RLM) on the various CCs being used to determine whether to declare a Radio Link Failure (RLF) to an upper layer (e.g., a V2X layer) of the TX UE, which may result in reconfiguration of the CCs (e.g., via SL-SRB3) or other events. FIGS. 6-10 are flow diagrams outlining various example methods for declaring RLF according to various aspects of the present disclosure.

[0053] For example, FIG. 6 is a flow diagram outlining an example method 600 for declaring RLF during SL communication, according to various aspects of the present disclosure. In the method 600, at operation 602, the TX UE may perform RLM on each SL-SRB3 CC and each SL-DRB CC independently. In some aspects, the TX UE may perform the RLM by monitoring, for each CC, whether a number of consecutive HARQ Discontinuous Transmission (DTX) events, which occur when a HARQ is not received at the TX UE, surpasses a first threshold. Such tracking may occur at the PHY and / or MAC level of the TX UE. Also, in some aspects, the TX UE may monitor whether the number of retransmissions to the RX UE (e.g., for any Service Data Unit (SDU) segment) at the Radio Link Control (RLC) layer for each CC surpasses a second threshold.

[0054] At operation 604, the TX UE may determine whether a CC of the SL-SRB3 and / or the one or more SL-DRBs has failed. In some aspects, the TX UE may monitor the HARQ DTX events and the number of RLC retransmissions for each used CC and determine that a CC hasfailed if either or both HARQ DTX events and the number of RLC retransmissions for any single CC has surpassed its associated threshold.

[0055] At operation 606, the TX UE may declare an RLF to an upper layer (e.g., the V2X layer) of the TX UE for each failed CC, as determined by the TX UE in operation 604. In some aspects, the upper layer may respond to an RLF for a CC by performing a “keep-alive” check for the failed one or more CCs. In some aspects, upon receiving an RLF for a CC, the upper layer may start a timer and attempt to reconfigure the CCs of sidelink connection with the RX UE if the associated CC continues to fail.

[0056] Further, at operation 608, the TX UE, if in an RRC_CONNECTED state with a base station (e.g., a RAN node 122 of FIG. 1), may report failure information concerning the declared RLF of the one or more CCs to the base station, such as by way of an RRC message. In some aspects, such an RRC message may indicate one or more of the destination L2 identifier associated with the failed CC, the identity of each failed CC for which an RLF was declared, and / or an indication as to whether the RLF was declared due to the number of consecutive HARQ DTX events for the CC surpassing the first threshold and / or due to the number of RLC retransmissions surpassing the second threshold.

[0057] FIG. 7 is a flow diagram outlining another example method 700 for declaring RLF during SL communication, according to various aspects of the present disclosure. In some aspects, the TX UE performs RLM specifically on each CC of SL-SRB3, as opposed to each CC of both SL-SRB3 and the one or more SL-DRBs, as discussed above in conjunction with method 600 of FIG. 6. In some aspects, when employing method 700 to focus on the SL-SRB3 CCs, the TX UE may reconfigure the CCs of the one or more SL-DRBs (e.g. by way of reconfiguring CCs, such as adding and / or releasing various CCs, or altering whether particular sets of CCs are configured for CA or packet duplication) based on reporting from the RX UE regarding SL Reference Signal Received Power (SL-RSRP) or CBR.

[0058] In method 700, at operation 702, the TX UE may perform RLM on each SL-SRB3 CC independently. In some aspects, to perform RLM, the TX UE may monitor, for each SL- SRB3 CC, whether a number of consecutive HARQ DTX events and / or a number of RLC retransmissions to the RX UE surpasses a corresponding threshold, as discussed above in connection with operation 602 of FIG. 6.

[0059] At operation 704, the TX UE detects a failure of an SL-SRB3 CC if the number of consecutive HARQ DTX events and / or a number of RLC retransmissions to the RX UE associated with that CC surpasses its corresponding threshold. Consequently, at operation 706, the TX UE may declare an RLF for each failed SL-SRB3 CC to an upper layer (e.g., a V2Xlayer) of the TX UE. In some aspects, the upper layer may respond to an RLF for a CC of the SL-SRB3 by performing a “keep-alive” check for the failed CC, as described above in connection with operation 606 of FIG. 6. Further, at operation 708, if in the RRC_CONNECTED state with a base station, the TX UE may report failure information concerning the declared RLF of the one or more SL-SRB3 CCs to the base station. In some aspects, the types of information that may be reported are as described above with respect to operation 608 of FIG. 6.

[0060] Moreover, at operation 710, the TX UE may determine whether all of the SL-SRB3 CC have failed as a result of the RLM performed in operation 702. If the TX UE determines that all SL-SRB3 CCs have filed, the TX UE, at operation 712, may initiate a carrier reconfiguration procedure (e.g., a PC5-RRC Reconfiguration, such as by way of an RRCReconfigurationSidelink message 318 of FIG. 3). In some aspects, the TX UE may employ the carrier reconfiguration procedure to remove the failed SL-SRB3 CCs and add or reconfigure one or more other CCs for the SL-SRB3.

[0061] FIGS. 8 A and 8B are a flow diagram outlining yet another example method 800 for declaring RLF during SL communication, according to various aspects described. In a manner similar to that of method 600 of FIG. 6, RLM is performed on each CC for SL-SRB3 and the one or more SL-DRBs. However, in method 800, a declared RLF for an SL-SRB3 CC may be handled differently from a declared RLF for a CC associated with the one or more SL-DRBs.

[0062] In method 800, at operation 802, the TX UE may perform RLM on each SL-SRB3 CC and each SL-DRB CC independently (e.g., by monitoring, for each CC, whether a number of consecutive HARQ DTX events and / or a number of RLC retransmissions to the RX UE for each CC surpasses a second threshold), as discussed above in conjunction with operation 602 of FIG. 6.

[0063] At operation 804, the TX UE may determine whether a CC of the SL-SRB3 and / or the one or more SL-DRBs has failed. In some aspects, as described above in connection with operation 604 of FIG. 6, the TX UE may monitor the HARQ DTX events and the number of RLC retransmissions for each used CC and determine that a CC has failed if either or both of the HARQ DTX events and the number of RLC retransmissions for any single CC has surpassed its associated threshold.

[0064] At operation 806, the TX UE may declare an RLF to an upper layer (e.g., the V2X layer) of the TX UE for each failed CC, as determined by the TX UE in operation 804. In some aspects, the upper layer may respond to an RLF for a CC by performing a “keep-alive” check for the failed one or more CCs (e.g., as discussed above in connection with operation 606 of FIG.6).

[0065] Further, at operation 808, the TX UE, if in an RRC_CONNECTED state with a gNB, may report failure information concerning the declared RLF of the one or more CCs to the gNB (e.g., as described above with respect to operation 608 of FIG. 6).

[0066] At operation 810, the TX UE may determine whether all of the SL-SRB3 carriers have failed (e.g., as described above in conjunction with operation 710 of FIG. 7). If the TX UE has determined that all SL-SRB3 CCs have failed, the TX UE, at operation 812, may initiate a carrier reconfiguration procedure for the SL-SRB3 CCs (e.g., as discussed above in connection with operation 712 of FIG. 7). Further, at operation 814, the TX UE may determine whether any of the failed CCs previously detected were associated with the one or more SL-DRBs. If so, the TX UE, at operation 816, may initiate a carrier reconfiguration procedure (e.g., a PC5-RRC Reconfiguration, such as by way of an RRCReconfigurationSidelink message 318 of FIG. 3). In some aspects, the TX UE may employ the carrier reconfiguration procedure to remove the failed one or more SL-DRB CCs and add or reconfigure one or more other CCs for the one or more SL-DRBs.

[0067] FIG. 9 is a flow diagram outlining yet another example method 900 for declaring RLF during SL communication, according to various aspects of the present disclosure. In contrast to methods 600, 700, and 800, in which a declared RLF is associated with a corresponding CC, method 900 may declare an RLF for the RX UE.

[0068] In method 900, at operation 902, the TX UE may perform RLM on each SL-SRB3 CC independently. In some aspects, as described above in connection with operation 702 of FIG. 7, the TX UE may perform the RLM by monitoring, for each SL-SRB3 CC, whether a number of consecutive HARQ DTX events surpasses a first threshold and / or a number of RLC retransmissions to the RX UE for each SL-SRB3 CC surpasses a second threshold.

[0069] At operation 904, the TX UE may determine whether the number of failed SL-SRB3 CCs, as detected by the TX UE, is greater than or equal to a third threshold (e.g., a value of X). For example, FIG. 10 is a flow diagram outlining an example method 1000 for employing a threshold number of carriers to determine whether to declare an RLF for the RX UE, according to various aspects of the present disclosure. In some aspects, the TX UE may perform the method 1000 for operation 904.

[0070] In the method 1000, at operation 1002, the TX UE may determine whether the number of SL-SRB3 CCs for which the corresponding number of consecutive HARQ DTX events is greater that the first threshold (THRESHOLD_1) is greater than the third threshold (X). If so, the TX UE, at operation 1006, may determine that an RLF has occurred for the RX UE. If,instead, at operation 1004, the TX UE determines that the number of SL-SRB3 CCs for which the corresponding number of consecutive HARQ DTX events is greater that the first threshold (THRESHOLD_1) is greater than X, then the TX UE may determine whether the number of SL- SRB3 CCs for which the corresponding RLC retransmission number is greater than the second threshold (THRESHOLD_2) is greater than X. If so, then at operation 1006, the TX UE may determine that an RLF has occurred for the RX UE. Otherwise, at operation 1008, the TX UE may determine that an RLF has not occurred for the RX UE.

[0071] In some aspects, the value of X may be an integer in a range from one to a total number of CCs associated with SL-SRB3. When X is one, the failure of a single CC associated with SL-SRB3 may cause an RLF to be declared for the RX UE. When X is equal to the total number of CCs of SL-SRB3, a failure of all such CCs may occur before the TX UE declares an RLF for the RX UE.

[0072] Returning to FIG. 9, at operation 904, if the number of failed SL-SRB3 CCs detected is greater than or equal to X, the UE TX, at operation 906, may declare an RLF for the RX UE to an upper layer (e.g., a V2X layer) of the TX UE. In some aspects, the TX UE may respond to an RLF for the RX UE by performing a “keep-alive” check for all CCs (e.g., all SL-SRB3 CCs and all CCs for the one or more SL-DRBs). In some aspects, upon receiving an RLF for the RX UE, the upper layer may start a timer and attempt to reconfigure the CCs of the SL connection with the RX UE if the RLF condition for the RX UE persists.

[0073] Further, at operation 908, the TX UE, if in an RRC_CONNECTED state with a base station, may report failure information concerning the declared RLF of RX UE to the base station, such as by way of an RRC message. In some aspects, such an RRC message may indicate one or more of the destination L2 identifier associated with the failed RX UE, the identity of each CC of the SL-SRB3 and the one or more SL-DRBs, the number of consecutive HARQ DTX events for each CC, and / or the number of RLC retransmissions for each CC.

[0074] As can be seen from the foregoing disclosure, aspects of the present disclosure provide a mechanism by which UEs may engage in SL unicast CA within NR without the designation of PCC and associated SCCs, thus providing the performance of CA and the reliability of packet duplication without the infrastructure associated with PCC / SCC differentiation. Solutions have also been provided for RLM by a TX UE and declaring an RLF associated with the SL communication between the TX UE and an RX UE.

[0075] Above are several flow diagrams outlining example methods and exchanges of messages. In this description and the appended claims, use of the term “determine” with reference to some entity (e.g., parameter, variable, and so on) in describing a method step orfunction is to be construed broadly. For example, “determine” is to be construed to encompass, for example, receiving and parsing a communication that encodes the entity or a value of an entity. “Determine” should be construed to encompass accessing and reading memory (e.g., lookup table, register, device memory, remote memory, and so on) that stores the entity or value for the entity. “Determine” should be construed to encompass computing or deriving the entity or value of the entity based on other quantities or entities. “Determine” should be construed to encompass any manner of deducing or identifying an entity or value of the entity.

[0076] As used herein, the term “identify”, when used with reference to some entity or value of an entity, is to be construed broadly as encompassing any manner of determining the entity or value of the entity. For example, the term “identify” is to be construed to encompass, for example, receiving and parsing a communication that encodes the entity or a value of the entity. The term “identify” should be construed to encompass accessing and reading memory (e.g., device queue, lookup table, register, device memory, remote memory, and so on) that stores the entity or value for the entity.

[0077] As used herein, the term “encode”, when used with reference to some entity or value of an entity, is to be construed broadly as encompassing any manner or technique for generating a data sequence or signal that communicates the entity to another component.

[0078] As used herein, the term “select”, when used with reference to some entity or value of an entity, is to be construed broadly as encompassing any manner of determining the entity or value of the entity from amongst a plurality or range of possible choices. For example, the term “select” is to be construed to encompass accessing and reading memory (e.g., lookup table, register, device memory, remote memory, and so on) that stores the entities or values for the entity and returning one entity or entity value from amongst those stored. The term “select” is to be construed as applying one or more constraints or rules to an input set of parameters to determine an appropriate entity or entity value. The term “select” is to be construed as broadly encompassing any manner of choosing an entity based on one or more parameters or conditions.

[0079] As used herein, the term “derive”, when used with reference to some entity or value of an entity, is to be construed broadly. “Derive” should be construed to encompass accessing and reading memory (e.g., lookup table, register, device memory, remote memory, and so on) that stores some initial value or foundational values and performing processing and / or logical / mathematical operations on the value or values to generate the derived entity or value for the entity. The term “derive” should be construed to encompass computing or calculating the entity or value of the entity based on other quantities or entities. The term “derive” should be construed to encompass any manner of deducing or identifying an entity or value of the entity.

[0080] As used herein, the term “indicate”, when used with reference to some entity (e.g., parameter or setting) or value of an entity, is to be construed broadly as encompassing any manner of communicating the entity or value of the entity, either explicitly or implicitly. For example, bits within a transmitted message may be used to explicitly encode an indicated value or may encode an index or other indicator that is mapped to the indicated value by prior configuration. The absence of a field within a message may implicitly indicate a value of an entity based on prior configuration.Examples

[0081] Example 1 is an apparatus for a user equipment (UE), including a memory and a processor, the processor coupled to the memory and configured to, when executing instructions stored in the memory, cause the UE to: receive, via the RF transceiver from a peer UE, an indication whether the peer UE supports sidelink (SL) carrier aggregation (CA); and transmit, via the RF transceiver to the peer UE, based on the peer UE supporting SL CA, an SL reconfiguration message configuring an SL data radio bearer (SL-DRB) to carry data from the UE to the peer UE.

[0082] Example 2 includes the subject matter of Example 1, including or omitting optional elements, wherein the SL reconfiguration message configures the SL-DRB for packet duplication or for SL CA.

[0083] Example 3 includes the subject matter of Example 1, including or omitting optional elements, wherein the SL reconfiguration message configures the SL-DRB with a first plurality of SL component carriers to carry the data from the UE to the peer UE.

[0084] Example 4 includes the subject matter of Example 3, including or omitting optional elements, wherein the processor is further configured to cause the UE to: select the first plurality of SL component carriers from a plurality of allowed SL component carriers for transmission to the peer UE.

[0085] Example 5 includes the subject matter of Example 3, including or omitting optional elements, wherein the processor is further configured to cause the UE to: transmit, via the RF transceiver to the peer UE, a first message enquiring at least one capability of the peer UE, wherein the indication whether the peer UE supports SL CA is included in a second message from the peer UE in response to the first message.

[0086] Example 6 includes the subject matter of Example 5, including or omitting optional elements, wherein the processor is further configured to cause the UE to transmit, to a base station, a third message indicting at least some information included in the second message.

[0087] Example 7 includes the subject matter of Example 5, including or omitting optionalelements, wherein at least one of the first message, the second message, or the SL reconfiguration message is transmitted over an SL signal radio bearer (SRB) 3 (SL-SRB3).

[0088] Example 8 includes the subject matter of Example 5, including or omitting optional elements, wherein the processor is further configured to cause the UE to: exchange, via the RF transceiver with the peer UE prior to the first message, a plurality of signaling messages over an SL signal radio bearer (SRB) 0 (SL-SRBO), an SL-SRB1, and an SL-SRB2 to establish a connection between the UE and the peer UE.

[0089] Example 9 includes the subject matter of Example 8, including or omitting optional elements, wherein the processor is further configured to cause the UE to: reuse an SL- ConfigCommonNR->sl-FreqInfoList-rl6 information element (IE) in a System Information Block (SIB) with a restriction of a single carrier to determine a single SL component carrier; map, in an upper layer of the UE, the SL-SRBO, the SL-SRB 1 , and the SL-SRB2 to the single SL component carrier; and map, in the upper layer of the UE, a Vehicle-to-Everything (V2X) service identifier to a Layer-2 (L2) destination address of the peer UE.

[0090] Example 10 includes the subject matter of Example 8, including or omitting optional elements, wherein the processor is further configured to cause the UE to: map, in an upper layer of the UE, at least one of the SL-SRBO, the SL-SRB 1 , or the SL-SRB2 to more than one corresponding SL component carrier; and map, in the upper layer of the UE, a Vehicle-to- Everything (V2X) service identifier to a Layer-2 (L2) destination address of the peer UE.

[0091] Example 11 includes the subject matter of Example 10, including or omitting optional elements, wherein each of the SL-SRBO, the SL-SRB 1 , or the SL-SRB2 is mapped to the more than one corresponding SL component carrier.

[0092] Example 12 includes the subject matter of Example 3, including or omitting optional elements, wherein the processor is further configured to cause the UE to: perform radio link monitoring (RLM) of at least one of the first plurality of SL component carriers, wherein the RLM is based on at least one of: a number of retransmissions to the peer UE at a radio link control (RLC) layer associated with each of the at least one of the first plurality of SL component carriers; or a number of consecutive hybrid automatic repeat request (HARQ) discontinuous transmission (DTX) events associated with each of the at least one of the first plurality of SL component carriers.

[0093] Example 13 includes the subject matter of Example 3, including or omitting optional elements, wherein the processor is further configured to cause the UE to: independently perform radio link monitoring (RLM) of each of the first plurality of SL component carriers; and declare, based on the RLM detecting a failure of a first SL component carrier of the first plurality of SLcomponent carriers, a radio link failure (RLF) of the first SL component carrier.

[0094] Example 14 includes the subject matter of Example 3, including or omitting optional elements, wherein: the SL reconfiguration message further configures an SL signal radio bearer 3 (SL-SRB3) for packet duplication with a second plurality of SL component carriers; and the processor is configured to: independently perform RLM of each of the first plurality of SL component carriers and each of the second plurality of SL component carriers; and declare, based on the RLM detecting a failure of a first SL component carrier of the first plurality of SL component carriers or the second plurality of SL component carriers, an RLF of the first SL component carrier.

[0095] Example 15 includes the subject matter of Example 3, including or omitting optional elements, wherein: the SL reconfiguration message further configures an SL signal radio bearer 3 (SL-SRB3) for packet duplication with a second plurality of SL component carriers; and the processor is configured to cause the UE to: independently perform RLM of each of the second plurality of SL component carriers; and declare, based on the RLM detecting a failure of a first SL component carrier of the second plurality of SL component carriers, an RLF of the first SL component carrier.

[0096] Example 16 includes the subject matter of Example 15, including or omitting optional elements, wherein the processor is further configured to cause the UE to: determine whether the RLM detected a failure of all of the second plurality of SL component carriers; and reconfigure, based on a determination that the RLM detected a failure of all of the second plurality of SL component carriers, one or more of the second plurality of SL component carriers.

[0097] Example 17 includes the subject matter of Example 16, including or omitting optional elements, wherein the processor is configured to cause the UE to: determine whether the RLM detected a failure of a second SL component carrier of the first plurality of SL component carriers; and reconfigure, based on a determination that the RLM detected a failure of a second SL component carrier of the first plurality of SL component carriers, one or more of the first plurality of SL component carriers.

[0098] Example 18 includes the subject matter of Example 16, including or omitting optional elements, wherein the processor is configured to cause the UE to: receive, via the RF transceiver from the peer UE, reception reporting regarding the first plurality of SL component carriers; and reconfigure, based on the reception reporting, one or more of the first plurality of SL component carriers.

[0099] Example 19 includes the subject matter of Example 3, including or omitting optionalelements, wherein: the SL reconfiguration message further configures an SL signal radio bearer 3 (SL-SRB3) for packet duplication with a second plurality of SL component carriers; and the processor is configured to cause the UE to: independently perform radio link monitoring (RLM) of each of the second plurality of SL component carriers; and declare, based on the RLM detecting a failure of at least a first number of the second plurality of SL component carriers, a radio link failure (RLF) for the peer UE.

[0100] Example 20 includes the subject matter of Example 19, including or omitting optional elements, wherein the first number is one.

[0101] Example 21 includes the subject matter of Example 19, including or omitting optional elements, wherein the first number is a total number of the second plurality of SL component carriers.

[0102] Example 22 is a method for a user equipment (UE), the method including: receiving, from a peer UE, an indication whether the peer UE supports sidelink (SL) carrier aggregation (CA); and transmitting, to the peer UE, based on the peer UE supporting SL CA, an SL reconfiguration message configuring an SL data radio bearer (SL-DRB) to carry data from the UE to the peer UE.

[0103] Example 23 includes the subject matter of Example 22, including or omitting optional elements, wherein the SL reconfiguration message configures the SL-DRB for packet duplication or for SL CA.

[0104] Example 24 includes the subject matter of Example 22, including or omitting optional elements, wherein the SL reconfiguration message configures the SL-DRB with a first plurality of SL component carriers to carry the data from the UE to the peer UE.

[0105] Example 25 includes the subject matter of Example 24, including or omitting optional elements, the method further including: selecting the first plurality of SL component carriers from a plurality of allowed SL component carriers for transmission to the peer UE.

[0106] Example 26 includes the subject matter of Example 24, including or omitting optional elements, the method further including: transmitting, to the peer UE, a first message enquiring at least one capability of the peer UE, wherein the indication whether the peer UE supports SL CA is included in a second message from the peer UE in response to the first message.

[0107] Example 27 includes the subject matter of Example 26, including or omitting optional elements, the method further including: transmitting, to a base station, a third message indicating at least some information included in the second message.

[0108] Example 28 includes the subject matter of Example 26, including or omittingoptional elements, wherein at least one of the first message, the second message, or the SL reconfiguration message is transmitted over an SL signal radio bearer (SRB) 3 (SL-SRB3).

[0109] Example 29 includes the subject matter of Example 26, including or omitting optional elements, the method further including: exchanging, with the peer UE prior to the first message, a plurality of signaling messages over an SL signal radio bearer (SRB) 0 (SL-SRB0), an SL-SRB 1, and an SL-SRB2 to establish a connection between the UE and the peer UE.

[0110] Example 30 includes the subject matter of Example 29, including or omitting optional elements, the method further including: reusing an SL-ConfigCommonNR->sL FreqlnfoList-rl 6 information element (IE) in a System Information Block (SIB) with a restriction of a single carrier to determine a single SL component carrier; mapping, in an upper layer of the UE, the SL-SRB0, the SL-SRB I, and the SL-SRB2 to the single SL component carrier; and mapping, in the upper layer of the UE, a service identifier to a Layer-2 (L2) destination address of the peer UE.

[0111] Example 31 includes the subject matter of Example 29, including or omitting optional elements, the method further including: mapping, in an upper layer of the UE, at least one of the SL-SRB0, the SL-SRB 1, or the SL-SRB2 to more than one corresponding SL component carrier; and mapping, in the upper layer of the UE, a service identifier to a Layer-2 (L2) destination address of the peer UE.

[0112] Example 32 includes the subject matter of Example 31, including or omitting optional elements, wherein each of the SL-SRB0, the SL-SRB 1, or the SL-SRB2 is mapped to the more than one corresponding SL component carrier.

[0113] Example 33 includes the subject matter of Example 24, including or omitting optional elements, the method further including: performing radio link monitoring (RLM) of at least one of the first plurality of SL component carriers, wherein the RLM is based on at least one of: a number of retransmissions to the peer UE at a radio link control (RLC) layer associated with each of the at least one of the first plurality of SL component carriers; or a number of consecutive hybrid automatic repeat request (HARQ) discontinuous transmission (DTX) events associated with each of the at least one of the first plurality of SL component carriers.

[0114] Example 34 includes the subject matter of Example 24, including or omitting optional elements, wherein the method further includes: independently performing radio link monitoring (RLM) of each of the first plurality of SL component carriers; and declaring, based on the RLM detecting a failure of a first SL component carrier of the first plurality of SL component carriers, a radio link failure (RLF) of the first SL component carrier.

[0115] Example 35 includes the subject matter of Example 24, including or omittingoptional elements, wherein: the SL reconfiguration message further configures an SL signal radio bearer 3 (SL-SRB3) for packet duplication with a second plurality of SL component carriers; and the method further includes: independently performing RLM of each of the first plurality of SL component carriers and each of the second plurality of SL component carriers; and declaring, based on the RLM detecting a failure of a first SL component carrier of the first plurality of SL component carriers or the second plurality of SL component carriers, an RLF of the first SL component carrier.

[0116] Example 36 includes the subject matter of Example 24, including or omitting optional elements, wherein: the SL reconfiguration message further configures an SL signal radio bearer 3 (SL-SRB3) for packet duplication with a second plurality of SL component carriers; and the method further includes: independently performing RLM of each of the second plurality of SL component carriers; and declaring, based on the RLM detecting a failure of a first SL component carrier of the second plurality of SL component carriers, an RLF of the first SL component carrier.

[0117] Example 37 includes the subject matter of Example 36, including or omitting optional elements, the method further including: determining whether the RLM detected a failure of all of the second plurality of SL component carriers; and reconfiguring, based on a determination that the RLM detected a failure of all of the second plurality of SL component carriers, one or more of the second plurality of SL component carriers.

[0118] Example 38 includes the subject matter of Example 37, including or omitting optional elements, the method further including: determining whether the RLM detected a failure of a second SL component carrier of the first plurality of SL component carriers; and reconfiguring, based on a determination that the RLM detected a failure of a second SL component carrier of the first plurality of SL component carriers, one or more of the first plurality of SL component carriers.

[0119] Example 39 includes the subject matter of Example 37, including or omitting optional elements, the method further including: receiving, from the peer UE, reception reporting regarding the first plurality of SL component carriers; and reconfiguring, based on the reception reporting, one or more of the first plurality of SL component carriers.

[0120] Example 40 includes the subject matter of Example 24, including or omitting optional elements, wherein: the SL reconfiguration message further configures an SL signal radio bearer 3 (SL-SRB3) for packet duplication with a second plurality of SL component carriers; and the method further includes: independently performing radio link monitoring (RLM) of each of the second plurality of SL component carriers; and declaring, based on theRLM detecting a failure of at least a first number of the second plurality of SL component carriers, a radio link failure (RLF) for the peer UE.

[0121] Example 41 includes the subject matter of Example 40, including or omitting optional elements, wherein the first number is one.

[0122] Example 42 includes the subject matter of Example 40, including or omitting optional elements, wherein the first number is a total number of the second plurality of SL component carriers.

[0123] Example 43 is a user equipment (UE), including a radio frequency (RF) transceiver and a baseband processor, the baseband processor configured to, when executing instructions stored in a memory, cause the UE to: select at least one first sidelink (SL) component carrier; exchange, via the RF transceiver with a peer UE, a plurality of signaling messages over an SL signal radio bearer (SRB) 0 (SL-SRB0), an SL-SRB1 , and an SL-SRB2 over the at least one first SL component carrier to establish a connection between the UE and the peer UE; transmit, via the RF transceiver to the peer UE, a capability enquiry message over the at least one first SL component carrier to enquire whether the peer UE supports SL carrier aggregation (CA); receive, via the RF transceiver from the peer UE in response to the capability enquiry message, a capability information message over the at least one first SL component carrier, the capability information message including an indication whether the peer UE supports SL CA; transmit, via the RF transceiver to the peer UE, based on the peer UE supporting SL CA, an SL reconfiguration message over the at least one first SL component carrier to configure at least one SL data radio bearer (SL-DRB) for packet duplication or for SL C A with a first plurality of SL component carriers; and transmitting, via the RF transceiver to the peer UE, data over the at least one SL-DRB using the first plurality of SL component carriers.

[0124] Example 44 includes the subject matter of Example 43, including or omitting optional elements, wherein: the at least one first SL component carrier includes a second plurality of SL component carriers; and at least one of the SL-SRB0, the SL-SRB1 , or the SL- SRB2 is configured for packet duplication with the second plurality of SL component carriers.

[0125] Example 45 includes the subject matter of Example 43, including or omitting optional elements, wherein: the at least one SL-DRB includes a plurality of SL-DRBs; and each of the plurality of SL-DRBs is individually configured for packet duplication or for SL CA.

[0126] Example 46 includes the subject matter of Example 43, including or omitting optional elements, wherein the first plurality of SL component carriers is a subset of a plurality of possible SL component carriers allocated to the UE.

[0127] Example 47 includes the subject matter of Example 43, including or omittingoptional elements, wherein the capability enquiry message, the capability information message, and the SL reconfiguration message are exchanged over an SL-DRB3.

[0128] Example 48 includes the subject matter of Example 47, including or omitting optional elements, wherein the SL-DRB3 is configured for packet duplication with a third plurality of SL component carriers.

[0129] Example 49 is a computer program product including program instructions which, when executed by a computer, cause implementation of the subject matter of any of Examples 20-38, including or omitting optional elements.

[0130] FIG. 11 is a diagram of an example of components of a wireless communication device according to one or more implementations described herein. In some implementations, the device 1100 can include application circuitry 1102, baseband circuitry 1104, RF circuitry 1 106, front-end module (FEM) circuitry 1 108, one or more antennas 1 110, and power management circuitry (PMC) 1112 coupled together at least as shown. The components of the illustrated device 1100 can be included in a UE or a RAN node. In some implementations, the device 1100 can include fewer elements (e.g., a RAN node may not utilize application circuitry 1 102, and instead include a processor / controller to process IP data received from a CN or an Evolved Packet Core (EPC)). In some implementations, the device 1100 can include additional elements such as, for example, memory / storage, display, camera, sensor (including one or more temperature sensors, such as a single temperature sensor, a plurality of temperature sensors at different locations in device 1100, etc.), or input / output ( I / O ) interface. In other implementations, the components described below can be included in more than one device (e.g., said circuitries can be separately included in more than one device for Cloud-RAN (C- RAN) implementations).

[0131] The application circuitry 1102 can include one or more application processors. For example, the application circuitry 1102 can include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processor(s) can include any combination of general-purpose processors and dedicated processors (e.g., graphics processors, application processors, etc.). The processors can be coupled with or can include memory / storage and can be configured to execute instructions stored in the memory / storage to enable various applications or operating systems to run on the device 1100. In some implementations, processors of application circuitry 1102 can process IP data packets received from an EPC.

[0132] The baseband circuitry 1104 can include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 1104 can include one or more baseband processors or control logic to process baseband signals received from a receive signalpath of the RF circuitry 1106 and to generate baseband signals for a transmit signal path of the RF circuitry 1106. Baseband circuitry 1104 can interface with the application circuitry 1102 for generation and processing of the baseband signals and for controlling operations of the RF circuitry 1106. For example, in some implementations, the baseband circuitry 1104 can include a 3G baseband processor 1104A, a 4G baseband processor 1104B, a 5G baseband processor 1104C, or other baseband processor(s) 1104D for other existing generations, generations in development or to be developed in the future (e.g., 5G, 6G, etc.).

[0133] The baseband circuitry 1104 (e.g., one or more of baseband processors 1104A-D) can handle various radio control functions that enable communication with one or more radio networks via the RF circuitry 1106. In other implementations, some or all of the functionality of baseband processors 1104A-D can be included in modules (e.g., sets of executable instructions) stored in the memory 1104G or other machine-readable or computer-readable medium (e.g., a non-transitory machine-readable or computer-readable storage medium) and executed via a Central Processing Unit (CPU) 1104E or another type of processor (e.g., a reduced instruction set computing (RISC) processor, a complex instruction set computing (CISC) processor, a graphics processing unit (GPU), a digital signal processor (DSP) such as a baseband processor, an application-specific integrated circuit (ASIC), a radio-frequency integrated circuit (RFIC), another processor, or any suitable combination thereof).

[0134] The radio control functions can include, but are not limited to, signal modulation / demodulation, encoding / decoding, radio frequency shifting, etc. In some implementations, modulation / demodulation circuitry of the baseband circuitry 1104 can include Fast-Fourier Transform (FFT), precoding, or constellation mapping / de-mapping functionality. In some implementations, encoding / decoding circuitry of the baseband circuitry 1104 can include convolution, tail-biting convolution, turbo, Viterbi, or Low-Density Parity Check (LDPC) encoder / decoder functionality. Implementations of modulation / demodulation and encoder / decoder functionality are not limited to these examples and can include other suitable functionality in other implementations.

[0135] In some implementations, the baseband circuitry 1104 can include one or more audio digital signal processor(s) (DSP) 1 104F. The audio DSPs 1104F can include elements for compression / decompression and echo cancellation and can include other suitable processing elements in other implementations. Components of the baseband circuitry 1104 can be suitably combined in a single chip, a single chipset, or disposed on a same circuit board in some implementations. In some implementations, some or all of the constituent components of the baseband circuitry 1104 and the application circuitry 1102 can be implemented together such as,for example, on a system-on-a-chip (SOC).

[0136] In some implementations, the baseband circuitry 1104 can provide for communication compatible with one or more radio technologies. For example, in some implementations, the baseband circuitry 1104 can support communication with an NG-RAN, an E-UTRAN or other wireless metropolitan area networks (WMAN), a wireless local area network (WLAN), a wireless personal area network (WPAN), etc. Implementations in which the baseband circuitry 1104 is configured to support radio communications of more than one wireless protocol can be referred to as multi-mode baseband circuitry.

[0137] RF circuitry 1106 can embody an RF transceiver that enables communication with wireless networks using modulated electromagnetic radiation through a non-solid medium. In various implementations, the RF circuitry 1106 can include switches, filters, amplifiers, etc. to facilitate the communication with the wireless network. RF circuitry 1106 can include a receive signal path which can include circuitry to down-convert RF signals received from the FEM circuitry 1108 and provide baseband signals to the baseband circuitry 1104. RF circuitry 1106 can also include a transmit signal path which can include circuitry to up-convert baseband signals provided by the baseband circuitry 1104 and provide RF output signals to the FEM circuitry 1108 for transmission.

[0138] In some implementations, the receive signal path of the RF circuitry 1106 can include mixer circuitry 1106A, amplifier circuitry 1106B, and filter circuitry 1106C. RF circuitry 1106 can also include synthesizer circuitry 1106D for synthesizing a frequency for use by the mixer circuitry 1 106 A of the receive signal path and the transmit signal path.

[0139] The RF circuitry 1106 can include analog-to-digital converter (ADC) and digital-to- analog converter (DAC) circuitry, and the baseband circuitry 1104 can include a digital baseband interface to communicate with the RF circuitry 1106.

[0140] Synthesizer circuitry 1106D of the RF circuitry 1106 can include a divider, a delay- locked loop (DLL), a multiplexer, and a phase accumulator.

[0141] FEM circuitry 1108 can include a receive signal path which can include circuitry configured to operate on RF signals received from one or more antennas 1110, amplify the received signals, and provide the amplified versions of the received signals to the RF circuitry 1 106 for further processing. FEM circuitry 1108 can also include a transmit signal path which can include circuitry configured to amplify signals for transmission provided by the RF circuitry 1106 for transmission by one or more of the one or more antennas 1110. In various implementations, the amplification through the transmit and / or receive signal paths can be done solely in the RF circuitry 1106, solely in the FEM circuitry 1108, or in both the RF circuitry1106 and the FEM circuitry 1108.

[0142] In some implementations, the FEM circuitry 1108 can include a TX / RX switch to switch between transmit mode and receive mode operation. The FEM circuitry can include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry can include an LNA to amplify received RF signals and provide the amplified received RF signals as an output (e.g., to the RF circuitry 1106). The transmit signal path of the FEM circuitry 1108 can include a power amplifier (PA) to amplify input RF signals (e.g., provided by RF circuitry 1 106), and one or more filters to generate RF signals for subsequent transmission (e.g., by one or more of the one or more antennas 1110).

[0143] Processors of the application circuitry 1102 and processors of the baseband circuitry 1104 can be used to execute elements of one or more instances of a protocol stack. For example, processors of the baseband circuitry 1 104, alone or in combination, can be used to execute Layer 3, Layer 2, or Layer 1 functionality, while processors of the baseband circuitry 1104 can utilize data (e.g., packet data) received from these layers and further execute Layer 4 functionality (e.g., transmission communication protocol (TCP) and user datagram protocol (UDP) layers). As referred to herein, Layer 3 can include a radio resource control (RRC) layer, described in further detail below. As referred to herein, Layer 2 can include a medium access control (MAC) layer, a radio link control (RLC) layer, and a PDCP layer, described in further detail below. As referred to herein, Layer 1 can include a physical (PHY) layer of a UE / RAN node.

[0144] In some implementations, the PMC 1112 can manage power provided to the baseband circuitry 1104. In particular, the PMC 1 1 12 can control power-source selection, voltage scaling, battery charging, or DC-to-DC conversion. The PMC 1112 can often be included when the device 1100 is capable of being powered by a battery, for example, when the device is included in a UE. The PMC 1112 can increase the power conversion efficiency while providing desirable implementation size and heat dissipation characteristics.

[0145] While FIG. 11 shows the PMC 1112 coupled only with the baseband circuitry 1104, in other implementations, the PMC 1112 may be additionally or alternatively coupled with, and perform similar power management operations for, other components such as, but not limited to, application circuitry 1102, RF circuitry 1106, or FEM circuitry 1108.

[0146] In some implementations, the PMC 1112 can control, or otherwise be part of, various power saving mechanisms of the device 1100. For example, if the device 1100 is in an RRC_CONNECTED state, where it is still connected to the RAN node as it expects to receive traffic shortly, then it can enter a state known as Discontinuous Reception (DRX) mode after a period of inactivity. During this state, the device 1100 can power down for brief intervals oftime and thus save power.

[0147] If there is no data traffic activity for an extended period of time, then the device 1100 can transition off to an RRC_IDLE state, where it disconnects from the network and does not perform operations such as channel quality feedback, handover, etc. The device 1100 goes into a very low power state and it performs paging where again it periodically wakes up to listen to the network and then powers down again. The device 1100 may not receive data in this state; in order to receive data, it can transition back to the RRC_CONNECTED state.

[0148] The baseband circuitry 1104, or the one or more baseband processors or control logic of the baseband circuitry 1104, may stand alone as the UE 110 or the RAN node 122 of FIG. 1 perform signaling and operation in the meaning as described throughout this disclosure.

[0149] Examples herein can include subject matter such as a method, means for performing acts or blocks of the method, at least one machine-readable medium including executable instructions that, when performed by a machine (e.g., a processor with memory, an applicationspecific integrated circuit (ASIC), a field-programmable gate array (FPGA), or the like) cause the machine to perform acts of the method or of an apparatus or system for concurrent communication using multiple communication technologies according to implementations and examples described.

[0150] In this regard, while the disclosed subject matter has been described in connection with various examples, implementations, aspects, etc., and corresponding Figures, where applicable, it is to be understood that other similar aspects can be used or modifications and additions can be made to the disclosed subject matter for performing the same, similar, alternative, or substitute function of the subject matter without deviating therefrom. Therefore, the disclosed subject matter should not be limited to any single example, implementation, or aspect described herein, but rather should be constmed in breadth and scope in accordance with the appended claims below.

[0151] In particular regard to the various functions performed by the above-described components or structures (assemblies, devices, circuits, systems, etc.), the terms (including a reference to a “means”) used to describe such components are intended to correspond, unless otherwise indicated, to any component or structure which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary implementations. In addition, while a particular feature may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any givenapplication.

[0152] As used herein, the term “or” is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise, or clear from context, “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, if X employs A; X employs B; or X employs both A and B, then “X employs A or B” is satisfied under any of the foregoing instances. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. Furthermore, to the extent that the terms “including”, “includes”, “having”, “has”, “with”, or variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.” Additionally, in situations wherein one or more numbered items are discussed (e.g., a “first X”, a “second X”, etc.), in general the one or more numbered items can be distinct, or they can be the same, although in some situations the context may indicate that they are distinct or that they are the same.

[0153] It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users.

Claims

CLAIMSWhat is claimed is:

1. A baseband processor configured to perform operations comprising: receiving, at a user equipment (UE) from a peer UE, an indication whether the peer UE supports sidelink (SL) carrier aggregation (CA); and generating, for the peer UE, based on the peer UE supporting SL CA, an SL reconfiguration message configuring an SL data radio bearer (SL-DRB) to carry data from the UE to the peer UE.

2. The baseband processor of claim 1, wherein the operations further comprise: generating, for the peer UE, a first message enquiring at least one capability of the peerUE, wherein the indication whether the peer UE supports SL CA is included in a second message from the peer UE in response to the first message.

3. The baseband processor of claim 2, wherein at least one of the first message, the second message, or the SL reconfiguration message comprises a PC5-Radio Resource Control (PC5- RRC) message.

4. The baseband processor of claim 2, wherein at least one of the first message, the second message, or the SL reconfiguration message is transmitted over an SL signal radio bearer (SRB) 3 (SL-SRB3).

5. The baseband processor of claim 1, wherein the SL reconfiguration message configures the SL-DRB for packet duplication or for SL CA.

6. The baseband processor of claim 1 , wherein the SL reconfiguration message configures the SL-DRB with a first plurality of SL component carriers to carry the data from the UE to the peer UE.

7. The baseband processor of claim 6, wherein the operations further comprise: causing radio link monitoring (RLM) of at least one of the first plurality of SL component carriers, wherein the RLM is based on at least one of:a number of retransmissions to the peer UE at a radio link control (RLC) layer associated with each of the at least one of the first plurality of SL component carriers; or a number of consecutive hybrid automatic repeat request (HARQ) discontinuous transmission (DTX) events associated with each of the at least one of the first plurality of SL component carriers.

8. The baseband processor of claim 6, wherein the operations further comprise: causing independent radio link monitoring (RLM) of each of the first plurality of SL component carriers; and declaring, based on the RLM detecting a failure of a first SL component carrier of the first plurality of SL component carriers, a radio link failure (RLF) of the first SL component carrier.

9. The baseband processor of claim 6, wherein: the SL reconfiguration message further configures an SL signal radio bearer 3 (SL- SRB3) for packet duplication with a second plurality of SL component carriers; and the operations further comprise: causing independent radio link monitoring (RLM) of each of the first plurality of SL component carriers and each of the second plurality of SL component carriers; and declaring, based on the RLM detecting a failure of a first SL component carrier of the first plurality of SL component carriers or the second plurality of SL component carriers, an RLF of the first SL component carrier.

10. The baseband processor of claim 6, wherein: the SL reconfiguration message further configures an SL signal radio bearer 3 (SL- SRB3) for packet duplication with a second plurality of SL component carriers; and the operations further comprise: causing independent radio link monitoring (RLM) of each of the second plurality of SL component carriers; and declaring, based on the RLM detecting a failure of a first SL component carrier of the second plurality of SL component carriers, an RLF of the first SL component carrier.

11. The baseband processor of claim 10, wherein the operations further comprise:determining whether the RLM detected a failure of all of the second plurality of SL component carriers; and reconfiguring, based on a determination that the RLM detected a failure of all of the second plurality of SL component carriers, one or more of the second plurality of SL component carriers.

12. The baseband processor of claim 1 1, wherein the operations further comprise: determining whether the RLM detected a failure of a second SL component carrier of the first plurality of SL component carriers; and reconfiguring, based on a determination that the RLM detected a failure of a second SL component carrier of the first plurality of SL component carriers, one or more of the first plurality of SL component carriers.

13. The baseband processor of claim 11, wherein the operations further comprise: receiving, from the peer UE, reception reporting regarding the first plurality of SL component carriers; and reconfiguring, based on the reception reporting, one or more of the first plurality of SL component carriers.

14. The baseband processor of claim 6, wherein: the SL reconfiguration message further configures an SL signal radio bearer 3 (SL- SRB3) for packet duplication with a second plurality of SL component carriers; and the operations further comprise: causing independent radio link monitoring (RLM) of each of the second plurality of SL component carriers; and declaring, based on the RLM detecting a failure of at least a first number of the second plurality of SL component carriers, a radio link failure (RLF) for the peer UE.

15. The baseband processor of claim 14, wherein the first number is one.

16. The baseband processor of claim 14, wherein the first number is a total number of the second plurality of SL component carriers.

17. A method for a user equipment (UE), the method comprising:receiving, from a peer UE, an indication whether the peer UE supports sidelink (SL) carrier aggregation (CA); and transmitting, to the peer UE, based on the peer UE supporting SL CA, an SL reconfiguration message configuring an SL data radio bearer (SL-DRB) to carry data from the UE to the peer UE.

18. The method of claim 17, wherein the SL reconfiguration message configures the SL- DRB for packet duplication or for SL CA.

19. The method of claim 17, wherein the SL reconfiguration message configures the SL- DRB with a first plurality of SL component carriers to carry the data from the UE to the peer UE.

20. The method of claim 19, further comprising: selecting the first plurality of SL component carriers from a plurality of allowed SL component carriers for transmission to the peer UE.

21. The method of claim 17, further comprising: transmit, to the peer UE, a first message enquiring at least one capability of the peer UE, wherein the indication whether the peer UE supports SL CA is included in a second message from the peer UE in response to the first message.

22. The method of claim 21 , wherein at least one of the first message, the second message, or the SL reconfiguration message is transmitted over an SL signal radio bearer (SRB) 3 (SL- SRB3).

23. The method of claim 21 , wherein at least one of the first message, the second message, or the SL reconfiguration message comprises a PC5-Radio Resource Control (PC5-RRC) message.

24. A user equipment (UE), comprising: a radio frequency (RF) transceiver; and at least one processor coupled to the RF transceiver and configured to, when executing instructions stored in a memory, cause the UE to performing operations comprising:receiving, via the RF transceiver from a peer UE, an indication whether the peer UE supports sidelink (SL) carrier aggregation (CA); and transmitting, via the RF transceiver to the peer UE, based on the peer UE supporting SL CA, an SL reconfiguration message configuring an SL data radio bearer (SL-DRB) to carry data from the UE to the peer UE.

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