Wireless terminal and method

Abstract

A wireless terminal (1A) performs sidelink communication with a peer wireless terminal (1B) using a primary carrier and a secondary carrier. The wireless terminal (1A) uses the primary carrier, without use of the secondary carrier, in order to transmit control plane data that belongs to a first-type sidelink signaling radio bearer and control plane data that belongs to a second-type sidelink signaling radio bearer. Thus, it is possible, for example, to contribute to enabling a wireless terminal to transmit, with a specific carrier, control plane data of one or more specific signaling radio bearers when sidelink communication is performed using a plurality of carriers.

Description

[Technical Field]

[0001] The present disclosure relates to direct communication between wireless terminals (device-to-device (D2D) communication), and more particularly to the use of multiple carriers in direct communication. [Background technology]

[0002] A form of communication in which a wireless terminal communicates directly with another wireless terminal without going through an infrastructure network such as a base station is generally called device-to-device (D2D) communication. D2D communication can be integrated with or supported by a cellular network. Proximity-based services (ProSe), defined in Third Generation Partnership Project (3GPP) Release 12 and later, provide a system architecture for cellular network-supported D2D communication. Cellular vehicle-to-everything (V2X) services, defined in 3GPP Release 14 and later, refer to ProSe and utilize D2D communication between wireless terminals. Cellular network-supported D2D communication can also be used for applications and services other than V2X services (e.g., public safety applications).

[0003] The interface between 3GPP radio terminals (i.e., User Equipment (UE)) used for the control plane and user plane for D2D communication is called the PC5 interface (or reference point). D2D communication over the PC5 interface is called sidelink communication. The PC5 interface can be based on Evolved Universal Terrestrial Radio Access (E-UTRA) sidelink capabilities or, further, on 5G New Radio (NR) sidelink capabilities. D2D communication (or sidelink communication) over the E-UTRA-PC5 (or Long Term Evolution (LTE)-based PC5) interface is connectionless, i.e., in broadcast mode at the Access Stratum (AS) layer. In contrast, sidelink communication over the NR PC5 interface supports unicast, groupcast, and broadcast modes at the AS layer.

[0004] Sidelink communication over the E-UTRA-PC5 interface is referred to, for example, as LTE sidelink communication. Sidelink communication over the NR PC5 interface is referred to, for example, as NR sidelink communication. 3GPP specifications define architectural enhancements to facilitate vehicular communications for cellular V2X services (see, for example, Non-Patent Documents 1, 2, and 3). LTE sidelink communication and NR sidelink communication play an important role in realizing cellular V2X communication. AS functionality using E-UTRA technology, including LTE sidelink communication to enable V2X communication between UEs, or V2X communication over the E-UTRA-PC5 interface, is referred to as V2X sidelink communication or LTE V2X sidelink communication. AS functionality using NR technology, including NR sidelink communication to enable V2X communication between UEs, or V2X communication over the NR PC5 interface, is referred to as NR V2X sidelink communication or simply NR sidelink communication.

[0005] 3GPP Release 15 supports carrier aggregation (CA) and multi-carrier operation for LTE sidelink communications (see Non-Patent Documents 1 and 4). For 3GPP Release 18, 3GPP will discuss sidelink evolution, which includes support for carrier aggregation for NR sidelink communications and support for sidelink over unlicensed spectrum (see Non-Patent Document 5).

[0006] Patent documents 1, 2, and 3 disclose sidelink (SL) carrier aggregation, i.e., carrier aggregation for SL communications, and in particular disclose signaling between UEs and between the UE and the radio access network (e.g., base station) regarding SL carrier aggregation.

[0007] Patent Document 1 describes that a UE may send an SL carrier aggregation configuration related to the addition, release, or modification of a secondary SL to a peer UE (see, for example, Figures 3, 4, 5, and 10 of Patent Document 1). The SL carrier aggregation configuration may be related to the addition, release, or modification of a secondary SL and may include a set of carrier frequencies and deactivation timer information. The SL carrier aggregation configuration may include an indication of reception (Rx) or transmission (Tx), an indication of a primary SL or a secondary SL, a carrier aggregation type (e.g., data duplication or data division), a V2X service type, a synchronization type, a primary SL index (carrier index), a secondary SL index (carrier index), and resource allocation information for SL transmission or reception.

[0008] Patent Document 1 describes that after PC5 carrier aggregation is configured, the UE may notify the base station of this (see, for example, Figure 6 of Patent Document 1). The notification message may include at least one of a set of carrier frequency information, an inactivity timer, and a peer UE identifier. For each SL component carrier, the notification message may further include a reception (Rx) or transmission (Tx) indication, a primary SL or secondary SL indication, a carrier aggregation type (e.g., data duplication or data division), a V2X service type, a synchronization type, a primary SL index (carrier index), a secondary SL index (carrier index), and resource allocation information for SL transmission or reception.

[0009] Patent Document 1 describes that a UE may transmit a request for SL carrier aggregation configuration between the UE and a peer UE to a base station, and that the base station may generate the configuration and provide it to the UE (see, for example, FIG. 9 of Patent Document 1). Patent Document 1 also describes that the request message is optional, and that the base station may provide the SL carrier aggregation configuration to the UE regardless of receiving a request message from the UE.

[0010] Patent Document 1 describes that before configuring SL carrier aggregation, UEs may directly exchange information regarding their respective SL carrier aggregation capabilities with each other (see, for example, Figure 13 of Patent Document 1). The SL carrier aggregation capability includes SL band combination information, SL band and Uu band combination information, or both. Uu is the air interface between the UE and the base station. The UE's band combination information indicates a list of carriers on which the UE can simultaneously operate and the band of each carrier. The UE may indicate whether it supports both transmission (Tx) and reception (Rx) on each carrier, or whether it supports only transmission (Tx) or reception (Rx).

[0011] Patent Document 2 describes that a UE receives a Radio Resource Control (RRC) signal (e.g., an RRC Connection Reconfiguration message) including a command to add or release a component carrier of V2X carrier aggregation from a wireless wide area network (WAN) (see, for example, Figures 2 and 3 of Patent Document 2).

[0012] Patent Document 3 describes a technique in which a first wireless terminal receives a sidelink message containing sidelink capability information of a second wireless terminal via a sidelink channel from the second wireless terminal and transmits an uplink message containing the sidelink capability information to a base station (see, for example, FIG. 25 of Patent Document 3). The sidelink capability information of the second wireless terminal may indicate whether the second wireless terminal supports sidelink multiple-carrier operation (e.g., sidelink carrier aggregation, sidelink multiple carriers, sidelink multi-carrier), a supported / operating sidelink (e.g., LTE, 5G, etc.), an available band, whether the second wireless terminal supports an unlicensed band (or unlicensed spectrum), etc. The base station may determine configuration parameters for sidelink communication between the first and second wireless terminals based on the sidelink capability information of the second wireless terminal and send the configuration parameters to the first wireless terminal. The configuration parameters may be transmitted in an RRC message, a Medium Access Control (MAC) Control Element (CE), or a Physical Downlink Control Channel (PDCCH) transmission (e.g., Downlink Control Information (DCI)).

[0013] Patent Document 3 describes a technique in which a first wireless terminal receives a sidelink message including band combination information of a second wireless terminal from the second wireless terminal via a sidelink channel and transmits an uplink message (e.g., an RRC message) including the band combination information to a base station (see, for example, FIG. 26 of Patent Document 3). The band combination information of the second wireless terminal may indicate one or more bands that the second wireless terminal is permitted to use simultaneously for sidelink communication. The band combination information of the second wireless terminal may also indicate whether the second wireless terminal supports multiple sidelink carriers (e.g., multi-carrier operation, sidelink carrier aggregation). For example, if the band combination information indicates that the second wireless terminal supports multiple sidelink carriers, the base station may determine or assign resources corresponding to the multiple carriers. The base station sends configuration parameters for sidelink communication between the first and second wireless terminals to the first wireless terminal. The configuration parameters may indicate sidelink resource assignment. More specifically, the radio resource allocation may indicate a first sidelink radio resource of a first carrier and a second sidelink radio resource of a second carrier, and the first wireless terminal may transmit a first transport block via the first sidelink radio resource and a second transport block via the second sidelink radio resource to the second wireless terminal. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] International Publication No. 2019 / 023857 [Patent Document 2] US Patent Application Publication No. 2019 / 0246377 [Patent Document 3] U.S. Patent Application Publication No. 2021 / 0051653 [Non-patent literature]

[0015] [Non-Patent Document 1] 3GPP TR 37.985 V17.0.0 (2021-12) "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Overall description of Radio Access Network (RAN) aspects for Vehicle-to-everything (V2X) based on LTE and NR (Release 17)", December 2021 [Non-patent document 2] 3GPP TS 23.287 V17.2.0 (2021-12) "3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Architecture enhancements for 5G System (5GS) to support Vehicle-to-Everything (V2X) services (Release 17)", December 2021 [Non-patent document 3] 3GPP TS 24.587 V17.4.1 (2021-12) "3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; Vehicle-to-Everything (V2X) services in 5G System (5GS); Stage 3 (Release 17)", December 2021 [Non-patent document 4] Huawei, HiSilicon, "WI summary for V2X phase 2 based on LTE", RP-180858, 3GPP TSG RAN Meeting #80, San Diego, USA, June 11-14, 2018 [Non-Patent Document 5] OPPO, LG Electronics, "New WID on NR sidelink evolution", RP-213678, 3GPP TSG RAN Meeting #94e, Electronic Meeting, December 6-17, 2021 Summary of the Invention [Problem to be solved by the invention]

[0016] The inventors have investigated carrier aggregation for D2D communications, including NR sidelink communications, and have identified various challenges. Carrier aggregation over a D2D interface or sidelink interface (e.g., PC5 interface) between wireless terminals can also be referred to as multi-carrier operation. One of these challenges relates to how UEs should use multiple sidelink carriers. For example, it may be preferable for certain types of messages or data, or more specifically, messages or data of certain types of radio bearers, to be transmitted over a specific sidelink carrier. The above-mentioned non-patent and patent documents do not provide a solution to enable this.

[0017] One of the objectives to be achieved by the embodiments disclosed in this specification is to provide an apparatus, a method, and a program that contribute to solving at least one of a plurality of problems, including the above-mentioned problem, related to carrier aggregation in a D2D interface between wireless terminals. It should be noted that this objective is only one of a plurality of objectives to be achieved by the embodiments disclosed in this specification. Other objectives or objectives and novel features will become apparent from the description of this specification or the accompanying drawings. [Means for solving the problem]

[0018] In a first aspect, a wireless terminal includes at least one radio transceiver and at least one processor coupled to the at least one radio transceiver. The at least one processor is configured to conduct sidelink communications with a peer wireless terminal on a primary carrier and a secondary carrier. The at least one processor is configured to use the primary carrier but not the secondary carrier to transmit control plane data belonging to a first type of sidelink signaling radio bearer and control plane data belonging to a second type of sidelink signaling radio bearer. The first type of sidelink signaling radio bearer is used to transmit unprotected upper layer messages. The second type of sidelink signaling radio bearer is used to transmit upper layer messages for establishing security for a unicast link for the sidelink communications.

[0019] In a second aspect, a method performed by a wireless terminal includes (a) conducting sidelink communications with a peer wireless terminal on a primary carrier and a secondary carrier, and (b) using the primary carrier but not the secondary carrier to transmit control plane data belonging to a first type of sidelink signaling radio bearer and a second type of sidelink signaling radio bearer, the first type of sidelink signaling radio bearer being used to transmit unprotected upper layer messages, and the second type of sidelink signaling radio bearer being used to transmit upper layer messages for establishing security for a unicast link for the sidelink communications.

[0020] In a third aspect, a program includes a group of instructions (software code) that, when loaded into a computer, causes the computer to perform the method according to the second aspect described above. [Effects of the Invention]

[0021] According to the above-described aspects, it is possible to provide an apparatus, a method, and a program that contribute to solving at least one of a plurality of problems related to carrier aggregation in a D2D interface between wireless terminals. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a diagram illustrating an example of the configuration of a wireless communication system according to an embodiment. [Figure 2] 1 is a diagram illustrating an example of the configuration of a wireless communication system according to an embodiment. [Figure 3] Figure 10 shows the AS control plane protocol stack for RRC on the PC5 interface. [Figure 4] Figure 10 shows the control plane AS protocol stack for PC5-S at the PC5 interface. [Figure 5] This figure shows the user plane AS protocol stack at the PC5 interface. [Figure 6] FIG. 1 is a diagram illustrating an example of the structure of NR sidelink layers 2 and 1 with carrier aggregation configured. [Figure 7] 10 is a flowchart illustrating an example of an operation of a UE according to the embodiment. [Figure 8] 10 is a flowchart illustrating an example of an operation of a UE according to the embodiment. [Figure 9] 10 is a flowchart illustrating an example of an operation of a UE according to the embodiment. [Figure 10] 10 is a flowchart illustrating an example of an operation of a UE according to the embodiment. [Figure 11] FIG. 10 is a diagram illustrating an example of signaling between UEs according to an embodiment. [Figure 12] FIG. 10 is a diagram illustrating an example of signaling between UEs according to an embodiment. [Figure 13] FIG. 10 is a diagram illustrating an example of signaling between UEs according to an embodiment. [Figure 14] FIG. 2 is a block diagram illustrating an example of the configuration of a UE according to the embodiment. [Figure 15] FIG. 2 is a block diagram illustrating a configuration example of a radio access network node according to the embodiment. [Figure 16] FIG. 2 is a block diagram illustrating an example configuration of a core network node and an application server according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, specific embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are designated by the same reference numerals, and for clarity of explanation, duplicate explanations will be omitted as necessary.

[0024] The multiple embodiments described below can be implemented independently or in appropriate combination. These multiple embodiments have different novel features. Therefore, these multiple embodiments contribute to solving different purposes or problems and to achieving different effects.

[0025] Although the following embodiments are primarily described for the 3GPP 5th generation mobile communication system (5G system), these embodiments may also be applied to other wireless communication systems that support D2D communication technologies similar to 3GPP NR sidelink communication.

[0026] As used herein, depending on the context, "if" may be construed to mean "when," "at or around the time," "after," "upon," "in response to determining," "in accordance with a determination," or "in response to detecting." These expressions may be construed to have the same meaning, depending on the context.

[0027] First, the configurations and operations of multiple network elements common to multiple embodiments will be described. Figure 1 shows an example configuration of a wireless communication system according to multiple embodiments. Each element (network function) shown in Figure 1 can be implemented, for example, as a network element on dedicated hardware, as a software instance running on dedicated hardware, or as a virtualized function instantiated on an application platform.

[0028] A Radio Access Network (RAN) node (e.g., gNB) 2 manages a cell 21 and can perform cellular communications (101 and 102) with multiple wireless terminals (UEs) 1, including UE 1A and UE 1B, using cellular communications technology (i.e., NR Radio Access Technology). Cellular communications 101 uses an air interface (e.g., Uu interface) between the RAN node 2 and UE 1A. Similarly, cellular communications 102 uses an air interface (e.g., Uu interface) between the RAN node 2 and UE 1B. While the example in FIG. 1 illustrates a situation in which UE 1A and UE 1B are located within the same cell 21 for simplicity, such an arrangement is merely an example. For example, UE 1A may be located within one cell of two adjacent cells managed by different RAN nodes 2, and UE 1B may be located within the other cell. Alternatively, at least one of UE1A and UE1B may be located outside the coverage of one or more RAN nodes 2 (ie, partial coverage, out-of-coverage).

[0029] Each of UE 1A and UE 1B has at least one radio transceiver and is configured to perform cellular communication (101 or 102) with RAN node 2 and D2D communication (i.e., sidelink communication) over a UE-to-UE direct interface (i.e., NR PC5 interface or NR sidelink) 103. The sidelink communication includes unicast mode communication (sidelink unicast) and may further include one or both of groupcast mode communication and broadcast mode communication.

[0030] The interface between 3GPP wireless terminals (i.e., UEs) used for the control plane and user plane for D2D communication is called the PC5 interface (or reference point). D2D communication over the PC5 interface is called sidelink communication. The PC5 interface can be based on E-UTRA sidelink capabilities and can also be based on 5G NR sidelink capabilities. D2D communication (or sidelink communication) over the E-UTRA-PC5 (or LTE-based PC5) interface is connectionless, i.e., in broadcast mode at the AS layer. In contrast, sidelink communication over the NR PC5 interface supports unicast, groupcast, and broadcast modes at the AS layer.

[0031] In some implementations, sidelink communication between UE 1A and UE 1B may be used for cellular V2X services and V2X communication. In other words, the UEs 1A and 1B and RAN node 2 shown in FIG. 1 may be used in a 5G system providing V2X communication over PC5. FIG. 2 illustrates an example of a non-roaming 5G system architecture for V2X communication over PC5. Each element (network function) shown in FIG. 2 can be implemented, for example, as a network element on dedicated hardware, as a software instance running on dedicated hardware, or as a virtualized function instantiated on an application platform. The major reference points (or interfaces) shown in FIG. 2 are described below.

[0032] In the following description, when describing matters common to multiple UEs including UE 1A and 1B, the reference numeral 1 will be used to simply refer to UE 1.

[0033] The V1 reference point is a reference point between a V2X application (e.g., V2X application 11A or V2X application 11B) in UE1 (e.g., UE1A or UE1B) and a V2X application in a V2X application server 61. The V2X application server 61 is located in a data network (DN) 50.

[0034] The V5 reference point is a reference point between V2X applications of two UEs 1 (e.g., UE 1A and UE 1B). The PC5 reference point is a reference point between UEs (e.g., UE 1A and UE 1B) and includes an NR-based PC5. The Uu reference point is a reference point between a UE (e.g., UE 1A) and the NG-RAN 20. Although not shown in FIG. 2, as already described, UE 1B may also communicate with the NG-RAN 20 via the Uu reference point.

[0035] The N1 reference point is a reference point between UE1 (e.g., UE1A) and an Access and Mobility management Function (AMF) 41 in a 5G Core Network (5GC) 40. The N1 reference point may be used to send V2X policies and parameters from the AMF 41 to UE1, and to send the UE1's V2X capability and PC5 capability for V2X communication from UE1 to the AMF 41. The N2 reference point is a reference point between the NG-RAN 20 and the AMF 41. The N2 reference point may be used to send V2X policies and parameters from the AMF 41 to the NG-RAN 20. The AMF 41 is one of the network function nodes in the control plane of the 5GC 40. The AMF 41 has a single signaling connection (i.e., N1 NAS signaling) with UE1 (e.g., UE1A). The AMF 41 terminates connections and provides registration management, connection management, and mobility management. The AMF 41 provides network function (NF) services to NF consumers (e.g., Session Management Function (SMF) 42) over a service-based interface (i.e., Namf interface). The NF services provided by the AMF 41 include a communication service (Namf_Communication), which enables NF consumers (e.g., SMF 42) to communicate with UE 1 or NG-RAN 20 via the AMF 41.

[0036] The N3 reference point is a reference point between the NG-RAN 20 and the User Plane Function (UPF) 43 in the 5GC. The N6 reference point is a reference point between the UPF 43 and the DN 50. The UPF 43 is one of the network function nodes in the user plane of the 5GC 40. The UPF 43 processes and forwards user data. The functionality of the UPF 43 is controlled by the SMF 42 via the N4 reference point. The UPF 43 may include multiple UPFs interconnected via the N9 reference point. For example, to enable the V2X application 11B in the UE 1A to communicate with the V2X application in the V2X application server 61, the UE 1A uses a path, association, session, or connection via the Uu reference point, the N3 reference point, and the N6 reference point.

[0037] The 5G system of FIG. 2 may provide a Network Exposure Function (NEF) service to enable communication between one or more network functions in the 5G Node B (5GC) 40 and the V2X application server 61. The NEF 46 is one of the network function nodes in the control plane of the 5G Node B (5GC) 40. The NEF 46 supports the exposure of services and capabilities from the 5G system to application functions and network functions inside and outside the operator network. The N33 reference point is the reference point between the NEF 46 and application functions (e.g., the V2X application server 61). The NEF 46 provides NF services to NF consumers (e.g., the V2X application server 61) over a service-based interface (i.e., the Nnef interface). In the case of V2X services, the services provided by the NEF 46 may be used by the V2X application server 61 to update V2X service-related information in the 5G Node B (5GC) 40. The NEF 46 may store V2X service related information in a Unified Data Repository (UDR) 45 either directly via the N37 reference point or via a Policy Control Function (PCF) 44.

[0038] Figures 3, 4, and 5 show the AS protocol stacks of the PC5 interface 103. As shown in Figure 3, the control plane Access Stratum (AS) protocol stack for the Sidelink Control Channel (SCCH) for Radio Resource Control (RRC) (i.e., PC5-RRC) includes RRC, Packet Data Convergence Protocol (PDCP), Radio Link Control (RLC), and Medium Access Control (MAC) sublayers, as well as a physical (PHY) layer. The SCCH is a sidelink logical channel for transmitting control information (i.e., PC5-RRC and PC5-S messages) from a UE (e.g., UE 1A) to other UEs (e.g., UE 1B).

[0039] The PC5 interface 103 supports the PC5 Signaling (PC5-S) protocol. As shown in Figure 4, in the control plane AS protocol stack for the SCCH for PC5-S, PC5-S resides above the PDCP, RLC, and MAC sublayers and the physical layer. PC5-S is used for control plane signaling on the PC5 interface 103 for secure unicast Layer 2 links (or PC5 unicast links). Specifically, PC5-S provides signaling for establishing, modifying, and releasing PC5 unicast links. The PC5 unicast link between UE1A and UE1B is associated with UE1A's Application Layer ID and Layer-2 ID and UE1B's Application Layer ID and Layer-2 ID. The PC5 unicast link is bidirectional. Therefore, UE1A can send application data (e.g., V2X service data, public safety service data) to UE1B over the PC5 unicast link with UE1B, and UE1B can also send application data to UE1A over the PC5 unicast link.

[0040] There is a one-to-one correspondence between a PC5 unicast link and a PC5-RRC connection. A PC5-RRC connection is a logical connection between two UEs1 for a pair of Source Layer-2 ID and Destination Layer-2 ID. A PC5-RRC connection is considered established after the corresponding PC5 unicast link is established. In other words, a PC5-RRC connection is established in response to the establishment of the corresponding PC5 unicast link. Specifically, when the transmission of a PC5-S message to a specific destination is requested by upper layers of a sidelink signaling radio bearer (SL SRB), UE1 (RRC layer) establishes a PDCP entity, an RLC entity, and an SCCH for the SL SRB for the PC5-S message based on the predefined SCCH configuration, and considers a PC5-RRC connection to be established for the destination. Alternatively, when the establishment of a PC5-RRC connection for a specific destination is indicated by the upper layer, UE1 (RRC layer) establishes the PDCP entity, the RLC entity, and the SCCH of the SL SRB for the PC5-RRC message of that destination based on the predefined SCCH configuration, and considers that the PC5-RRC connection is established.

[0041] Figure 5 shows the AS user plane protocol stack for the Sidelink Traffic Channel (STCH). The STCH is a sidelink logical channel for transmitting user data (e.g., V2X service data, public safety service data) from UE1 (e.g., UE1A) to other UE(s)1 (e.g., UE1B). The protocol stack includes the Service Data Adaptation Protocol (SDAP), PDCP, RLC, and MAC sublayers, as well as the physical layer.

[0042] NR sidelink communication over the NR PC5 interface 103 supports two resource allocation modes: Mode 1 and Mode 2.

[0043] In resource allocation mode 1, the RAN node 2 (e.g., gNB) performs resource allocation. For example, the RAN node 2 allocates or schedules SL radio resources to the UE 1 using the NR Uu interface 101. Resource allocation in mode 1 includes dynamic grants and configured grants.

[0044] In the case of a dynamic sidelink grant, UE1 needs to request resources from RAN node 2 for the transmission of every single transport block. More specifically, UE1 transmits a MAC Control Element (CE) (i.e., Sidelink BSR MAC CE) indicating a sidelink buffer status report (BSR) to RAN node 2 via the Uplink Shared Channel (UL-SCH) and the Physical Uplink Shared Channel (PUSCH). RAN node 2 then transmits Downlink Control Information (DCI) indicating a dynamic sidelink grant to UE1 via the Physical Downlink Control Channel (PDCCH). The dynamic sidelink grant provides resource allocation for the transmission (and retransmission) of one transport block. Note that if sidelink carrier aggregation (described later) is configured, the dynamic sidelink grant may provide resource allocation for one transport block per sidelink (component) carrier.

[0045] In the case of a configured grant, RAN node 2 grants UE 1 periodic sidelink resources semi-statically configured by RRC. More specifically, UE 1 may transmit UE assistance information regarding the traffic pattern of sidelink communications to RAN node 2. Such UE assistance information, or the sidelink traffic pattern information transmitted in the UE assistance information, may be referred to as configured grant assistance information. The sidelink traffic pattern information (or configured grant assistance information) may indicate, for example, a maximum transport block size based on the observed traffic pattern, estimated packet arrival timing on the sidelink logical channel, and estimated data arrival period on the sidelink logical channel. UE 1 transmits the UE assistance information including the sidelink traffic pattern information using an RRC message (e.g., a UE assistance information message). RAN node 2 may generate a configured grant based on the sidelink traffic pattern information received from UE 1. RAN node 2 sends a configured grant to UE1 using an RRC message (e.g., an RRCReconfiguration message). The configured grant indicates the allocation of time and frequency resources and the periodicity of the resource allocation. There are two types of configured grants for Mode 1. In configured grant type 1, the configured grant is assigned or released to UE1 by RRC signaling and can be used immediately. In configured grant type 2, RAN node 2 assigns the configured grant to UE1 via RRC signaling and activates or deactivates the configured grant via DCI signaling. UE1 can use the periodic resources assigned in the configured grant only after it has been activated by RAN node 2 and until it is deactivated.

[0046] On the other hand, in resource allocation mode 2, UE1 autonomously selects resources based on its own sensing. The sensing is performed in a preconfigured resource pool. UE1 can select resources for sidelink transmissions and retransmissions if these resources are not being used by other UEs for high priority traffic. UE1 can perform a certain number of transmissions and retransmissions on the selected resources until a cause for resource reselection is triggered.

[0047] UE1A and UE1B support carrier aggregation (CA) over the NR PC5 interface (or NR sidelink) 103. In other words, UE1A and UE1B support NR sidelink carrier aggregation, i.e., carrier aggregation for NR sidelink communications. Sidelink carrier aggregation can also be referred to as multicarrier operation. Sidelink carrier aggregation enables UE1A and UE1B to communicate with each other over multiple sidelink carriers. Similar to the terminology used in the Uu interface, multiple sidelink carriers used in sidelink carrier aggregation may be referred to as component carriers. In one example, one or more of the multiple sidelink carriers may belong to a licensed spectrum (licensed band) licensed to RAN node 2 (or NG-RAN 20) or its operator, and one or more may belong to an unlicensed spectrum. The unlicensed spectrum may be an ITS spectrum for intelligent transportation systems (ITS).

[0048] UE1A and UE1B support sidelink carrier aggregation for unicast transmission. UE1A and UE1B may support sidelink carrier aggregation for groupcast transmission. UE1A and UE1B may support sidelink carrier aggregation for broadcast transmission.

[0049] In sidelink carrier aggregation, one or both of UE1A and UE1B may not necessarily be able to transmit simultaneously on multiple sidelink carriers. In other words, one or both of UE1A and UE1B may not support transmission on multiple sidelink carriers in the same time slot. A UE with such limited transmission capabilities may be referred to as a limited Tx capability UE. For example, limited Tx capability may be due to the number of transmit chains of UE1 being smaller than the number of configured transmit sidelink carriers. Alternatively, limited Tx capability may be due to UE1 not supporting the band combination of the configured transmit sidelink carriers. Alternatively, limited Tx capability may be due to the time required for UE1 to switch transmit chains. Alternatively, limited Tx capability may be due to UE1 being unable to meet radio frequency (RF) requirements due to, for example, a power spectral density (PSD) imbalance.

[0050] Similarly, in sidelink carrier aggregation, one or both of UE1A and UE1B may not necessarily be able to receive on multiple sidelink carriers simultaneously. In other words, one or both of UE1A and UE1B may not support reception on multiple sidelink carriers within the same time slot. UE1 with such limited reception capabilities may be referred to as a limited Rx capability UE.

[0051] Figure 6 shows an example of the structure of NR sidelink layers 2 and 1 with carrier aggregation configured. Sidelink layer 2 includes a MAC sublayer 601, an RLC sublayer 602, a PDCP sublayer 603, and an SDAP sublayer 604. Basically, sidelink carrier aggregation is a concept of the MAC sublayer 601 and the physical layer 620 and does not apply to layers above the RLC sublayer 602. However, as described below, a PC5-RRC message related to sidelink carrier aggregation may be introduced.

[0052] The physical layer 620 supports multiple sidelink carriers. If the UE supports transmission on multiple sidelink carriers in the same timeslot, the physical layer 620 can transmit one transport block (or MAC Protocol Data Unit (PDU)) on each sidelink carrier in one timeslot. The physical layer 620 offers transport channels to the MAC sublayer 601.

[0053] The MAC sublayer 601 provides one MAC entity for transmission and reception on multiple sidelink carriers. The MAC entity provides a hybrid automatic repeat request (HARQ) entity per sidelink carrier. The single HARQ entity maintains multiple HARQ processes, allowing transmissions to continue on the corresponding sidelink carrier while waiting for HARQ feedback regarding the success or failure of the previous transmission.

[0054] The MAC sublayer 601 provides logical channels to the RLC sublayer 602. The MAC sublayer 601 provides mapping between logical channels and transport channels and multiplexes MAC Service Data Units (SDUs) belonging to one or different logical channels. Transport channels used in the NR sidelink include the Sidelink Shared Channel (SL-SCH) and the Sidelink Broadcast Channel (SL-BCH). Logical channels used in the NR sidelink include the Sidelink Control Channel (SCCH), the Sidelink Traffic Channel (STCH), and the Sidelink Broadcast Control Channel (SBCCH). The SCCH is a control channel and is mapped to the SL-SCH. The STCH is a traffic channel and is also mapped to the SL-SCH like the SCCH. The SBCCH is a control channel and is mapped to the SL-BCH.

[0055] The MAC sublayer 601 provides scheduling for the NR sidelink, including priority handling among multiple logical channels through logical channel prioritization.

[0056] If the UE supports transmission on multiple sidelink carriers in the same time slot and has grants on each of the multiple sidelink carriers, the MAC sublayer provides multiple transport blocks (MAC PDUs) to the physical layer 620 over multiple transport channels (i.e., SL-SCHs) associated with the multiple sidelink carriers for transmission on the multiple sidelink carriers in the same time slot. Each grant may be a dynamic or configured grant of resource allocation mode 1. Alternatively, if the MAC entity is configured for sidelink resource allocation mode 2 transmission using a resource pool, the MAC entity may generate a sidelink grant selected based on random selection or sensing in the resource pool.

[0057] The RLC sublayer 602 provides RLC channels to the PDCP sublayer 603. The RLC sublayer 602 supports three transmission modes: Acknowledged Mode (AM), Unacknowledged Mode (UM), and Transparent Mode (TM). In AM and UM, the RLC sublayer 602 provides segmentation of RLC SDUs. In AM, the RLC sublayer 602 provides ARQ (retransmission of RLC SDUs or RLC SDU segments).

[0058] The PDCP sublayer 603 provides Data Radio Bearers (DRBs) to the SDAP sublayer 604. The PDCP sublayer 603 receives user plane data for the DRBs from the SDAP sublayer 604 and provides header compression, integrity protection, ciphering, and the like.

[0059] Additionally, the PDCP sublayer 603 provides signaling radio bearers (SRBs) to upper layers (i.e., PC5-S layer, PC-5 RRC layer), receives control plane data (i.e., PC5-S messages and PC5-RRC messages) for SRBs from the PC5-S layer and PC-5 RRC layer, and provides integrity protection, ciphering, etc.

[0060] The SDAP sublayer 604 provides handling of Quality of Service (QoS) flows. QoS flows may be Internet Protocol (IP) flows, i.e., IP packets. Alternatively, QoS flows may be non-IP flows, i.e., non-IP packets. The SDAP sublayer 604 provides a mapping between QoS flows and SL DRBs. For each destination, there is one SDAP entity for each unicast, groupcast, and broadcast associated with that destination.

[0061] A receiving UE (e.g., UE 1B) transmits a Physical Sidelink Feedback Channel (PSFCH) in response to a PSSCH received several slots earlier. The number of slots after a UE receives a PSSCH transmission in which it can transmit HARQ feedback for that PSSCH transmission depends on the period of the PSFCH symbols and the minimum time gap between the slot with the PSSCH transmission and the slot containing the PSFCH for HARQ feedback. Within a resource block, resources for the PSFCH are periodically configured, for example, with a period of 1, 2, or 4 slots. In other words, within a resource pool, a slot with a PSFCH exists every 1, 2, or 4 slots. Furthermore, for each resource pool, a minimum number of slots (i.e., a minimum time gap) between a slot with a PSSCH transmission and a slot containing a PSFCH for HARQ feedback for that PSSCH transmission is configured. The minimum time gap is, for example, 2 or 3.

[0062] Specifically, the PSFCH configuration (e.g., SL-PSFCH-Config) including the configuration of PRBs used for PSFCH transmission and reception (e.g., sl-PSFCH-RB-Set), the PSFCH periodicity (e.g., sl-PSFCH-Period), and the minimum time gap (e.g., sl-MinTimeGapPSFCH) can be included in the sidelink resource pool configuration. The sidelink resource pool configuration (e.g., SL-BWP-PoolConfigCommon) can be included in the sidelink common configuration (e.g., SL-BWP-ConfigCommon in SL-ConfigCommonNR) broadcast in system information (e.g., System Information Block 12 (SIB12)). Alternatively, the sidelink resource pool configuration (e.g., SL-BWP-PoolConfig) can be included in the sidelink configuration (e.g., SL-BWP-PoolConfig in sl-ConfigDedicatedNR) transmitted in a UE-specific RRC message (e.g., RRCReconfiguration message). Alternatively, the sidelink resource pool configuration (e.g., SL-BWP-PoolConfigCommon) can be included in the sidelink configuration preconfigured in the UE (e.g., SL-BWP-PoolConfig in SL-PreconfigurationNR).

[0063] The receiving UE transmits the PSFCH in the first slot that includes the PSFCH resource and is located at least the number of slots specified by the minimum time gap setting (e.g., sl-MinTimeGapPSFCH) of the resource pool after the last slot of PSSCH reception. Therefore, if the PSFCH period is four slots, HARQ feedback for PSSCH transmission in four PSSCH slots can be transmitted in multiple PRBs in one PSFCH symbol in one slot.

[0064] First Embodiment This embodiment provides an improvement regarding carrier aggregation in the NR sidelink. Specifically, this embodiment relates to clarifying the mapping between sidelink radio bearers and aggregated sidelink carriers. The configurations and operations of the wireless communication system and network elements (or apparatuses, nodes, devices, or network functions) according to this embodiment may be similar to those of the examples described with reference to FIGS. 1 to 6.

[0065] FIG. 7 illustrates an example of the operation of UE1 (e.g., UE1A). In step 701, UE1A performs sidelink communication with peer UE1B over a primary carrier and one or more secondary carriers. In other words, UE1A uses the primary carrier and one or more secondary carriers to perform sidelink communication with peer UE1B. The sidelink communication may be unicast.

[0066] In step 702, UE 1A uses the primary carrier, without using the secondary carrier, to transmit control plane data belonging to a first type of sidelink signaling radio bearer (SL SRB) and a second type of sidelink signaling radio bearer (SL SRB). The first type of SL SRB is used to transmit unprotected upper layer messages (e.g., PC5-S messages). The second type of SL SRB is used to transmit upper layer messages (e.g., PC5-S messages) to establish security for a unicast link (e.g., PC5 unicast link) for sidelink communication. This security may be PC5-S security or Access Stratum (AS) security. This security enables the PDCP sublayer 603 to protect the signaling (or messages in SL SRBs) and user plane data (or data in SL DRBs) transmitted between UE 1A and UE 1B.

[0067] That is, the first type of SL SRB may be Sidelink Signalling Radio Bearer 0 (SL-SRB0), and the second type of SL SRB may be Sidelink Signalling Radio Bearer 1 (SL-SRB1). For a unicast PC5-RRC connection, SL-SRB0 is used to transmit one or more PC5-S messages before PC5-S security is established, while SL-SRB1 is used to transmit multiple PC5-S messages to establish PC5-S security.

[0068] Specifically, UE 1A may distinguish the first and second types of SL SRBs or the first and second logical channels (i.e., SCCHs) associated therewith from other SL SRBs and SL DRBs or the logical channels (i.e., SL SRBs and SL DRBs) associated therewith. UE 1A may then include data of the first and second logical channels (i.e., MAC SDUs) in a transport channel, one or more transport blocks, or one or more MAC PDUs transmitted on the primary carrier. Such an operation may be performed by the MAC sublayer 601 of UE 1A or a MAC entity within the MAC sublayer 601.

[0069] A primary carrier may also be referred to as a primary component carrier, primary link, primary sidelink, or primary unicast link. Similarly, a secondary carrier may also be referred to as a secondary component carrier, secondary link, secondary sidelink, or secondary unicast link.

[0070] In some implementations, the primary carrier may be the carrier on which a bidirectional PC5 unicast link or PC5-RRC connection is initially established, while the secondary carrier may be the carrier that is activated for transmission on the PC5 unicast link associated with the PC5-RRC connection after the PC5-RRC connection is established on the primary carrier. Secondary carriers may be added, modified, or released by exchanging PC5-RRC signaling on the PC5-RRC connection between UE 1A and peer UE 1B via the primary carrier.

[0071] According to the operation of UE1 described with reference to Figure 7, UE1 can transmit control plane data (or messages) for specific SL SRBs on a specific sidelink carrier.

[0072] In addition, UE1 may use the primary carrier without using the secondary carrier to transmit control plane data belonging to a third-type SL SRB. The third-type SL SRB is used to transmit higher layer messages (e.g., PC5-S messages) after security (e.g., PC5-S security or AS security) is established. Specifically, the third-type SL SRB may be Sidelink Signalling Radio Bearer 2 (SL-SRB2).

[0073] Furthermore, UE1 may use the primary carrier without using the secondary carrier to transmit control plane data belonging to a fourth type of SL SRB. The fourth type of SL SRB is used to transmit PC5-RRC messages after PC5-S security or AS security is established. Specifically, the fourth type of SL SRB may be Sidelink Signalling Radio Bearer 3 (SL-SRB3).

[0074] UE1 may operate to use one or more secondary carriers for transmitting user data belonging to one or more SL DRBs, but not to use these secondary carriers for transmitting control plane data belonging to any SL SRBs.

[0075] The above-described operation of the MAC sublayer 601 (or MAC entity) of UE1 to transmit one or more specific sidelink radio bearers, particularly one or more specific SL SRBs, on the primary carrier is effective, for example, when the primary carrier belongs to a licensed spectrum and the secondary carrier belongs to an unlicensed spectrum. The unlicensed spectrum may be an ITS spectrum. Licensed spectrum is likely to provide relatively more stable or higher-quality wireless communication than unlicensed spectrum due to the lack of contention with other wireless systems. Therefore, transmitting control messages for SL SRBs (e.g., SL SRB0, SL SRB1, etc.) required for establishing and maintaining a PC5 unicast link and a PC5-RRC connection on a primary carrier belonging to a licensed spectrum can contribute to providing a stable PC5 unicast link and a PC5-RRC connection.

[0076] <Second embodiment> This embodiment provides an improvement regarding carrier aggregation in the NR sidelink. Specifically, this embodiment relates to a method for configuring, determining, or selecting a sidelink primary carrier and a secondary carrier. The configurations and operations of the wireless communication system and network elements (or apparatuses, nodes, devices, or network functions) according to this embodiment may be similar to those described with reference to FIGS. 1 to 6.

[0077] FIG. 8 illustrates an example of the behavior of UE1 when UE1 is out of the coverage of RAN node 2 (or NG-RAN 20). UE1 has a memory configured to store first configuration parameters indicating a carrier frequency or multiple candidate carrier frequencies of a primary carrier and a carrier frequency or multiple candidate carrier frequencies of a secondary carrier. The memory may be a non-volatile memory in a Mobile Equipment (ME) or a Universal Subscriber Identity Module (USIM). The first configuration parameters may also be referred to as configuration information, pre-configuration parameters, or pre-configuration information. The first configuration parameters may be provided to UE1 from a core network node (e.g., AMF 41, PCF 44) via the N1 reference point between AMF 41 and UE1. Alternatively, the first configuration parameters may be provided to UE1 from a V2X application server 61 via the V1 reference point between UE1 and V2X application server 61. In step 801, UE1 obtains the first configuration parameters. This may mean that UE1 reads the first configuration parameters from the memory. Alternatively, this may mean that UE1 receives the first configuration parameters from a core network node or V2X application server 61 and stores them in memory.

[0078] In step 802, when UE1 is out of the coverage of RAN node 2 (or NG-RAN 20), UE1 determines the carrier frequency of a primary carrier and the carrier frequency of a secondary carrier according to first configuration parameters stored in a memory. UE1 may determine the carrier frequencies of multiple secondary carriers. UE1 may determine whether UE1 is in the coverage in the same manner as in the conventional method. UE1 being in the coverage of RAN node 2 or NG-RAN 20 may mean that UE1 has selected any cell provided by RAN node 2 or NG-RAN 20 according to cell selection criteria or cell reselection criteria and is camping on that cell. UE1 being out of the coverage of RAN node 2 or NG-RAN 20 may mean that none of the cells provided by RAN node 2 or NG-RAN 20 is a suitable cell for UE1 to camp on.

[0079] In a first implementation, the first configuration parameters may explicitly specify a carrier frequency of the primary carrier and explicitly specify a carrier frequency of the secondary carrier. The first configuration parameters may explicitly specify a carrier frequency for each of the multiple secondary carriers.

[0080] In a second implementation, the first configuration parameter may specify a carrier frequency of the primary carrier and provide multiple candidate carrier frequencies of the secondary carrier, in which case, when the UE1 is out of the coverage of the RAN node 2 (or the NG-RAN 20), the UE1 may autonomously select a secondary carrier from the multiple candidate carriers.

[0081] In a third implementation, the first configuration parameter may provide multiple candidate carrier frequencies for the primary carrier and multiple candidate carrier frequencies for the secondary carrier, in which case, when UE1 is out of the coverage of RAN node 2 (or NG-RAN 20), UE1 may autonomously select the primary carrier from the multiple candidate carriers and autonomously select the secondary carrier from the multiple candidate carriers.

[0082] Note that the multiple candidate carrier frequencies of the primary carrier may be the same as or common to the multiple candidate carrier frequencies of the secondary carrier. In other words, the first configuration parameters may provide multiple candidate sidelink carrier frequencies, each of which can be used as a primary carrier or a secondary carrier. UE1 may autonomously select the primary carrier and the secondary carrier from the multiple candidate carrier frequencies. The multiple candidate carrier frequencies common to the primary carrier and the sidelink carrier may be multiple resource pools. In other words, the first configuration parameters may be multiple resource pool configurations.

[0083] The autonomous selection of the primary carrier in the third implementation and the autonomous selection of the secondary carrier in the second and third implementations may be performed as follows: In one example, UE1 may randomly select or determine the primary carrier from multiple candidate carrier frequencies. Similarly, UE1 may randomly select or determine the secondary carrier from multiple candidate carrier frequencies.

[0084] In another example, UE1 may measure the Channel Busy Ratio (CBR) of multiple candidate carrier frequencies. UE1 may select or determine a primary carrier by comparing the CBRs of the multiple candidate carrier frequencies. Specifically, UE1 may select a carrier with the lowest CBR as the primary carrier among the multiple candidate carriers. Alternatively, UE1 may select or determine a primary carrier from one or more candidate carrier frequencies whose CBR is below a threshold. UE1 may similarly select a secondary carrier.

[0085] In yet another example, UE1 may select or determine a primary carrier by comparing Sidelink Reference Signal Received Power (SL-RSRP) of multiple candidate carrier frequencies. The SL-RSRP measurements of the multiple candidate carrier frequencies may be performed by UE1 itself. Alternatively, UE1 may receive SL-RSRP measurement results from one or more other UEs.

[0086] 9 shows an example of the operation of UE1 when UE1 is within the coverage of RAN node 2 (or NG-RAN 20). Step 901 is similar to step 801 in FIG. 8. In step 902, when UE1 is within the coverage of RAN node 2 (or NG-RAN 20), UE1 receives second configuration parameters from RAN node 2 (or NG-RAN 20), the second configuration parameters indicating the carrier frequency of the primary carrier or multiple candidate carrier frequencies. UE1 may receive the second configuration parameters from RAN node 2 via non-UE-specific signaling (e.g., system information broadcast) or UE-specific signaling (e.g., RRC signaling).

[0087] In step 903, UE1 selects or determines the carrier frequency of the primary carrier according to the second configuration parameters. The second configuration parameters may explicitly specify the carrier frequency of the primary carrier. Alternatively, the second configuration parameters may provide multiple candidate carrier frequencies for the primary carrier. In this case, UE1 autonomously selects the primary carrier from the multiple candidate carrier frequencies. The selection of the carrier frequency of the primary carrier by UE1 may be similar to some methods described with reference to FIG. 8. Specifically, UE1 may randomly select or determine the primary carrier from the multiple candidate carrier frequencies. Alternatively, UE1 may select or determine the primary carrier by comparing the CBR or SL-RSRP of the multiple candidate carrier frequencies.

[0088] Furthermore, UE1 selects or determines the carrier frequency of the secondary carrier according to the (pre-configured) first configuration parameter. The selection of the carrier frequency of the secondary carrier based on the first configuration parameter may be similar to that described with reference to FIG. 8.

[0089] Figure 10 shows another example of the behavior of UE1 when UE1 is in the coverage of RAN node 2 (or NG-RAN 20). In the example of Figure 10, when UE1 is in the coverage, RAN node 2 (or NG-RAN 20) further provides a third configuration parameter indicating the carrier frequency of the secondary carrier or multiple candidate carrier frequencies.

[0090] Step 1001 is similar to step 801 in Figure 8 and step 901 in Figure 9. Similar to step 902 in Figure 9, in step 1002, when UE1 is within the coverage of RAN node 2 (or NG-RAN 20), UE1 receives second configuration parameters from RAN node 2 (or NG-RAN 20), the second configuration parameters indicating a carrier frequency of a primary carrier or a plurality of candidate carrier frequencies. Furthermore, UE1 receives third configuration parameters from RAN node 2 (or NG-RAN 20), the third configuration parameters indicating a carrier frequency of a secondary carrier or a plurality of candidate carrier frequencies. UE1 may receive the second and third configuration parameters from RAN node 2 via non-UE-specific signaling (e.g., system information broadcast) or UE-specific signaling (e.g., RRC signaling).

[0091] In step 1003, UE1 selects or determines the carrier frequency of the primary carrier according to the second configuration parameter. This operation may be similar to the operation described in step 903 of FIG.

[0092] Furthermore, UE1 selects or determines the carrier frequency of the secondary carrier according to a third configuration parameter. The third configuration parameter may explicitly specify the carrier frequency of the secondary carrier. Alternatively, the second configuration parameter may provide multiple candidate carrier frequencies for the secondary carrier. In this case, UE1 autonomously selects the secondary carrier from the multiple candidate carrier frequencies. The selection of the carrier frequency of the secondary carrier by UE1 may be similar to some methods described with reference to FIG. 8. Specifically, UE1 may randomly select or determine the secondary carrier from the multiple candidate carrier frequencies. Alternatively, UE1 may select or determine the secondary carrier by comparing the CBR or SL-RSRP of the multiple candidate carrier frequencies.

[0093] As described above, the second configuration parameter may indicate multiple candidate carrier frequencies for the primary carrier, and the third configuration parameter may indicate multiple candidate carrier frequencies for the secondary carrier. In this case, the multiple candidate carrier frequencies for the primary carrier may be the same as or common to the multiple candidate carrier frequencies for the secondary carrier. UE1 may select the primary carrier and the secondary carrier from the common multiple candidate carrier frequencies. The multiple candidate carrier frequencies common to the primary carrier and the sidelink carrier may be multiple resource pools. In other words, the second and third configuration parameters may be multiple resource pool configurations.

[0094] According to the operation of UE1 described with reference to Figures 8 to 10, UE1 can determine the primary and secondary carriers for sidelink communication in coverage, out-of-coverage, or both.

[0095] <Third embodiment> This embodiment provides an improvement regarding carrier aggregation in the NR sidelink. Specifically, this embodiment provides signaling between UEs for sidelink carrier aggregation. The configurations and operations of the wireless communication system and network elements (or apparatuses, nodes, devices, or network functions) according to this embodiment may be similar to those of the examples described with reference to FIGS. 1 to 6.

[0096] UE1 (e.g., UE1A) sends a control message to peer UE1 (e.g., UE1B) indicating addition, modification, or release of a secondary carrier. The control message may be a PC5-RRC message.

[0097] 11 shows an example of signaling between UEs regarding the addition of a secondary carrier. In step 1101, UE 1A sends an RRCReconfigurationSidelink message. The message indicates the addition of a secondary carrier. The message may include a secondary carrier addition request. The message may include a secondary carrier configuration. The secondary carrier configuration may include an indication of the secondary carrier (or an indication of the carrier frequency of the secondary carrier).

[0098] If UE 1B can comply with all of the settings included in the RRCReconfigurationSidelink message, including the addition of a secondary carrier, it applies these settings. Then, in step 1102, UE 1B transmits an RRCReconfigurationCompleteSidelink message to UE 1A. In response, if UE 1B cannot comply with (some of) the settings included in the RRCReconfigurationSidelink message, it transmits an RRCReconfigurationFailureSidelink message to UE 1A. For example, if UE 1B does not support the carrier frequency of the secondary carrier specified in the secondary carrier configuration, or if UE 1B does not support the combination of the carrier frequency of the primary carrier and the carrier frequency of the secondary carrier specified in the secondary carrier configuration, UE 1B may respond to UE 1A with an RRCReconfigurationFailureSidelink message.

[0099] In addition to the PC5-RRC message for adding a secondary carrier shown in Figure 11, UE1A may send a control message, control information, or control command to UE1B to activate or deactivate the configured secondary carrier. The control message, information, or command may be a MAC CE (e.g., Activation / Deactivation MAC CE).

[0100] 12 shows an example of signaling between UEs regarding secondary carrier modification. In step 1201, UE 1A sends an RRCReconfigurationSidelink message. The message indicates modification of the secondary carrier. The message may include a secondary carrier modification request. The message may include modified or updated secondary carrier settings. The modified or updated secondary carrier settings may indicate that the carrier frequency of the secondary carrier is changed.

[0101] If UE 1B can comply with all of the settings included in the RRCReconfigurationSidelink message, including the secondary carrier modification, it applies these settings. Then, in step 1202, UE 1B sends an RRCReconfigurationCompleteSidelink message to UE 1A. In response, if UE 1B cannot comply with (some of) the settings included in the RRCReconfigurationSidelink message, it sends an RRCReconfigurationFailureSidelink message to UE 1A. For example, if UE 1B does not support the changed carrier frequency of the secondary carrier or does not support the combination of the carrier frequency of the primary carrier and the changed carrier frequency of the secondary carrier, UE 1B may respond to UE 1A with an RRCReconfigurationFailureSidelink message.

[0102] 13 shows an example of signaling between UEs regarding the release of a secondary carrier. In step 1301, UE 1A sends an RRCReconfigurationSidelink message. The message indicates the release of the secondary carrier. The message may include a Secondary Carrier Release Request. The message may also include an indication (e.g., an identifier or index) of the secondary carrier to be released.

[0103] If UE 1B can comply with all of the settings included in the RRCReconfigurationSidelink message, including the release of the secondary carrier, it applies these settings. Then, in step 1202, UE 1B sends an RRCReconfigurationCompleteSidelink message to UE 1A. In response, if UE 1B cannot comply with (some of) the settings included in the RRCReconfigurationSidelink message, it sends an RRCReconfigurationFailureSidelink message to UE 1A. For example, if UE 1B cannot comply with the release of the secondary carrier, it may respond to UE 1A with an RRCReconfigurationFailureSidelink message.

[0104] According to the operations of UE1A and UE1B described with reference to Figures 11 to 13, these UEs can add, modify, and release secondary carriers for the NR sidelink.

[0105] Next, exemplary configurations of a UE 1, a RAN node 2, a core network node such as an AMF 41, and a V2X application server 61 according to the above-described embodiments will be described below. FIG. 14 is a block diagram showing an exemplary configuration of a UE 1. A Radio Frequency (RF) transceiver 1401 performs analog RF signal processing for communication with other UEs 1 and the RAN node 2. The RF transceiver 1401 may include multiple transceivers. The analog RF signal processing performed by the RF transceiver 1401 includes frequency up-conversion, frequency down-conversion, and amplification. The RF transceiver 1401 is coupled to an antenna array 1402 and a baseband processor 1403. The RF transceiver 1401 receives modulation symbol data (or OFDM symbol data) from the baseband processor 1403, generates a transmit RF signal, and provides the transmit RF signal to the antenna array 1402. The RF transceiver 1401 also generates a baseband receive signal based on the received RF signal received by the antenna array 1402 and supplies the generated signal to the baseband processor 1403. The RF transceiver 1401 may include an analog beamformer circuit for beamforming. The analog beamformer circuit may include, for example, multiple phase shifters and multiple power amplifiers.

[0106] The baseband processor 1403 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. Digital baseband signal processing includes (a) data compression / decompression, (b) data segmentation / concatenation, (c) transmission format (transmission frame) generation / decomposition, (d) transmission path coding / decoding, (e) modulation (symbol mapping) / demodulation, and (f) generation of OFDM symbol data (baseband OFDM signal) using Inverse Fast Fourier Transform (IFFT). Meanwhile, control plane processing includes communication management of Layer 1 (e.g., transmit power control), Layer 2 (e.g., radio resource management and hybrid automatic repeat request (HARQ) processing), and Layer 3 (e.g., signaling related to attachment, mobility, and call management).

[0107] For example, the digital baseband signal processing by the baseband processor 1403 may include signal processing of a Service Data Adaptation Protocol (SDAP) layer, a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, a Medium Access Control (MAC) layer, and a Physical (PHY) layer. Furthermore, the control plane processing by the baseband processor 1403 may include processing of a Non-Access Stratum (NAS) protocol, a Radio Resource Control (RRC) protocol, MAC Control Elements (CEs), and Downlink Control Information (DCIs). The control plane processing may include processing of PC5-S signaling and PC5-RRC signaling.

[0108] The baseband processor 1403 may perform Multiple Input Multiple Output (MIMO) encoding and precoding for beamforming.

[0109] The baseband processor 1403 may include a modem processor (e.g., a Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., a Central Processing Unit (CPU) or a Micro Processing Unit (MPU)) that performs control plane processing. In this case, the protocol stack processor that performs control plane processing may be shared with the application processor 1404, which will be described later.

[0110] The application processor 1404 is also referred to as a CPU, an MPU, a microprocessor, or a processor core. The application processor 1404 may include multiple processors (multiple processor cores). The application processor 1404 executes a system software program (operating system (OS)) and various application programs (e.g., a calling application, a web browser, a mailer, a camera operation application, and a music playback application) read from the memory 1406 or other memories, thereby realizing various functions of the UE1.

[0111] In some implementations, the baseband processor 1403 and the application processor 1404 may be integrated on a single chip, as indicated by the dashed line (1405) in Figure 14. In other words, the baseband processor 1403 and the application processor 1404 may be implemented as a single System on Chip (SoC) device 1405. An SoC device may also be called a system Large Scale Integration (LSI) or a chipset.

[0112] The memory 1406 is volatile memory, nonvolatile memory, or a combination thereof. The memory 1406 may include multiple physically independent memory devices. The volatile memory may be, for example, static random access memory (SRAM), dynamic RAM (DRAM), or a combination thereof. The nonvolatile memory may be mask read only memory (MROM), electrically erasable programmable ROM (EEPROM), flash memory, a hard disk drive, or any combination thereof. For example, the memory 1406 may include an external memory device accessible from the baseband processor 1403, the application processor 1404, and the SoC 1405. The memory 1406 may also include an internal memory device integrated within the baseband processor 1403, the application processor 1404, or the SoC 1405. Furthermore, the memory 1406 may include memory within a universal integrated circuit card (UICC).

[0113] The memory 1406 may store one or more software modules (computer programs) 1407 including instructions and data for performing the processes by the UE 1 described in the above embodiments. In some implementations, the baseband processor 1403 or the application processor 1404 may be configured to read and execute the software modules 1407 from the memory 1406 to perform the processes by the UE 1 described in the above embodiments with reference to the drawings.

[0114] It should be noted that the control plane processing and operations performed by UE1 described in the above embodiment can be realized by elements other than the RF transceiver 1401 and the antenna array 1402, namely, at least one of the baseband processor 1403 and the application processor 1404, and the memory 1406 storing the software module 1407.

[0115] FIG. 15 is a block diagram showing an example configuration of a RAN node 2 according to the above embodiment. Referring to FIG. 15, the RAN node 2 includes a radio frequency transceiver 1501, a network interface 1503, a processor 1504, and a memory 1505. The RF transceiver 1501 performs analog RF signal processing for communication with UEs 1 and other UEs. The RF transceiver 1501 may include multiple transceivers. The RF transceiver 1501 is coupled to an antenna array 1502 and the processor 1504. The RF transceiver 1501 receives modulation symbol data from the processor 1504, generates a transmit RF signal, and provides the transmit RF signal to the antenna array 1502. The RF transceiver 1501 also generates a baseband receive signal based on the receive RF signal received by the antenna array 1502 and provides the baseband receive signal to the processor 1504. The RF transceiver 1501 may include an analog beamformer circuit for beamforming. The analog beamformer circuitry includes, for example, multiple phase shifters and multiple power amplifiers.

[0116] The network interface 1503 is used to communicate with network nodes (e.g., other RAN nodes, and control and forwarding nodes of the core network), and may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series.

[0117] The processor 1504 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. The processor 1504 may include multiple processors. For example, the processor 1504 may include a modem processor (e.g., a Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., a Central Processing Unit (CPU) or a Micro Processing Unit (MPU)) that performs control plane processing. The processor 1504 may include a digital beamformer module for beamforming. The digital beamformer module may include a Multiple Input Multiple Output (MIMO) encoder and precoder.

[0118] The memory 1505 is configured by a combination of volatile memory and non-volatile memory. The volatile memory is, for example, Static Random Access Memory (SRAM), Dynamic RAM (DRAM), or a combination thereof. The non-volatile memory is, for example, Mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or a hard disk drive, or any combination thereof. The memory 1505 may include storage located remotely from the processor 1504. In this case, the processor 1504 may access the memory 1505 via the network interface 1503 or other I / O interface.

[0119] The memory 1505 may store one or more software modules (computer programs) 1506 including instructions and data for performing the processing by the RAN node 2 described in the above embodiments. In some implementations, the processor 1504 may be configured to read and execute the software modules 1506 from the memory 1505 to perform the processing by the RAN node 2 described in the above embodiments.

[0120] It should be noted that if the RAN node 2 is a Central Unit (CU) (e.g., gNB-CU) or a CU Control Plane Unit (CU-CP) (e.g., gNB-CU-CP), the RAN node 2 may not include the RF transceiver 1501 (and the antenna array 1502).

[0121] Fig. 16 shows an example configuration of the AMF 41. Other core network nodes and the V2X application server 61E in the 5GC 40 may also have a configuration similar to that shown in Fig. 16. Referring to Fig. 16, the AMF 41 includes a network interface 1601, a processor 1602, and a memory 1603. The network interface 1601 is used, for example, to communicate with other network functions (NFs) or nodes. The network interface 1601 may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series.

[0122] The processor 1602 may be, for example, a microprocessor, a microprocessing unit (MPU), or a central processing unit (CPU). The processor 1602 may include multiple processors.

[0123] The memory 1603 is composed of volatile memory and nonvolatile memory. The memory 1603 may include multiple physically independent memory devices. The volatile memory is, for example, Static Random Access Memory (SRAM), Dynamic RAM (DRAM), or a combination thereof. The nonvolatile memory is, for example, Mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or a hard disk drive, or any combination thereof. The memory 1603 may include storage located remotely from the processor 1602. In this case, the processor 1602 may access the memory 1603 via the network interface 1601 or another I / O interface.

[0124] The memory 1603 may store one or more software modules (computer programs) 1604 including instructions and data for performing processing by the AMF 41 described in the above-described embodiments. In some implementations, the processor 1602 may be configured to read and execute the software modules 1604 from the memory 1603, thereby performing processing by the AMF 41 described in the above-described embodiments.

[0125] As described with reference to FIGS. 14, 15, and 16, each of the processors included in the UE 1, the RAN node 2, the core network node such as the AMF 41, and the V2X application server 61 according to the above-described embodiments can execute one or more programs including instructions for causing a computer to perform the algorithms described with reference to the drawings. The programs include instructions (or software code) that, when loaded into a computer, cause the computer to perform one or more functions described in the embodiments. The programs may be stored in a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable media or tangible storage media include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technology, CD-ROM, digital versatile disk (DVD), Blu-ray (registered trademark) disc or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage device. The programs may also be transmitted on a transitory computer-readable medium or a communication medium. By way of example, and not limitation, transitory computer-readable or communication media include electrical, optical, acoustic, or other forms of propagated signals.

[0126] The above-described embodiments are merely examples of application of the technical ideas obtained by the inventors of the present invention. In other words, the technical ideas are not limited to the above-described embodiments, and various modifications are possible.

[0127] For example, some or all of the above embodiments can be described as, but are not limited to, the following supplementary notes.

[0128] (Appendix 1) at least one radio transceiver; at least one processor coupled to the at least one wireless transceiver; The at least one processor: performing sidelink communication with a peer wireless terminal on the primary carrier and the secondary carrier; using the primary carrier without using the secondary carrier for transmitting control plane data belonging to a sidelink signaling radio bearer of a first type and control plane data belonging to a sidelink signaling radio bearer of a second type; It is configured as the first type of sidelink signaling radio bearer is used to transmit unprotected upper layer messages; the second type sidelink signaling radio bearer is used to transmit higher layer messages for establishing security for unicast links related to the sidelink communication; Wireless terminal. (Appendix 2) The upper layer message is a PC5 Signalling (PC5-S) message. 1. A wireless terminal as defined in claim 1. (Appendix 3) the first type sidelink signaling radio bearer is a Sidelink Signalling Radio Bearer 0 (SL-SRB0); The second type of sidelink signaling radio bearer is a Sidelink Signalling Radio Bearer 1 (SL-SRB1). 3. A wireless terminal according to claim 1 or 2. (Appendix 4) the at least one processor is configured to provide a Medium Access Control (MAC) entity; the MAC entity is configured to include data of logical channels associated with the sidelink signaling radio bearer of the first type and data of logical channels associated with the sidelink signaling radio bearer of the second type in one or more MAC Protocol Data Units (PDUs) transmitted on the primary carrier. 4. The wireless terminal according to claim 1. (Appendix 5) the at least one processor is configured to use the primary carrier without using the secondary carrier for transmitting control plane data belonging to a sidelink signaling radio bearer of a third type; the third type sidelink signaling radio bearer is used to transmit higher layer messages after the security has been established; 5. The wireless terminal according to any one of Supplementary notes 1 to 4. (Appendix 6) The third type of sidelink signaling radio bearer is a Sidelink Signalling Radio Bearer 2 (SL-SRB2). 6. A wireless terminal as defined in claim 5. (Appendix 7) the at least one processor is configured to use the primary carrier without using the secondary carrier for transmitting control plane data belonging to a fourth type of sidelink signaling radio bearer; The fourth type sidelink signaling radio bearer is used to transmit PC5 Radio Resource Control (PC5-RRC) messages after the security is established. 7. A wireless terminal according to claim 5 or 6. (Appendix 8) The fourth type of sidelink signaling radio bearer is Sidelink Signalling Radio Bearer 3 (SL-SRB3). 8. The wireless terminal of claim 7. (Appendix 9) the at least one processor is configured to use the secondary carrier for transmitting user data belonging to a sidelink data radio bearer, but not to use the secondary carrier for transmitting control plane data belonging to any sidelink signaling radio bearer. 9. The wireless terminal according to any one of Supplementary notes 1 to 8. (Appendix 10) the primary carrier belongs to a licensed spectrum of a radio access network node to which the wireless terminal is connected, and the secondary carrier belongs to an unlicensed spectrum; 10. The wireless terminal according to any one of Supplementary notes 1 to 9. (Appendix 11) a memory configured to store a first setting parameter indicating a carrier frequency or a plurality of candidate carrier frequencies of the primary carrier and a carrier frequency or a plurality of candidate carrier frequencies of the secondary carrier; The at least one processor: configured to determine a carrier frequency of the primary carrier and a carrier frequency of the secondary carrier according to the first configuration parameters stored in the memory when the wireless terminal is out of coverage of a radio access network; 11. The wireless terminal according to claim 1. (Appendix 12) The memory is a non-volatile memory in a Mobile Equipment (ME) or a Universal Subscriber Identity Module (USIM), 12. The wireless terminal of claim 11. (Appendix 13) the first configuration parameter is provided to the wireless terminal from a core network node or a vehicle-to-everything (V2X) application server; 13. The wireless terminal of claim 11 or 12. (Appendix 14) the at least one processor is configured to receive, when the wireless terminal is within a coverage area of ​​the wireless access network, second configuration parameters indicating a carrier frequency of the primary carrier or a plurality of candidate carrier frequencies from the wireless access network, and determine a carrier frequency of the primary carrier according to the second configuration parameters. 14. The wireless terminal according to any one of Supplementary notes 11 to 13. (Appendix 15) the at least one processor is configured to determine a carrier frequency of the secondary carrier according to the first configuration parameter when the wireless terminal is within coverage of the radio access network. 15. The wireless terminal of claim 14. (Appendix 16) the at least one processor is configured to receive, when the wireless terminal is within coverage of the radio access network, a third configuration parameter indicating a carrier frequency of the secondary carrier or a plurality of candidate carrier frequencies, and to determine a carrier frequency of the secondary carrier according to the third configuration parameter. 15. The wireless terminal of claim 14. (Appendix 17) the at least one processor is configured to send a PC5 Radio Resource Control (PC5-RRC) message to the peer wireless terminal indicating the addition, modification, or release of the secondary carrier. 17. A wireless terminal according to any one of Supplementary notes 1 to 16. (Appendix 18) conducting sidelink communications with a peer wireless terminal on a primary carrier and a secondary carrier; and using the primary carrier without using the secondary carrier for transmitting control plane data belonging to a sidelink signaling radio bearer of a first type and control plane data belonging to a sidelink signaling radio bearer of a second type; Equipped with the first type of sidelink signaling radio bearer is used to transmit unprotected upper layer messages; the second type sidelink signaling radio bearer is used to transmit higher layer messages for establishing security for unicast links related to the sidelink communication; A method performed by a wireless terminal. (Appendix 19) A program for causing a computer to perform a method for a wireless terminal, comprising: The method comprises: conducting sidelink communications with a peer wireless terminal on a primary carrier and a secondary carrier; and using the primary carrier without using the secondary carrier for transmitting control plane data belonging to a sidelink signaling radio bearer of a first type and control plane data belonging to a sidelink signaling radio bearer of a second type; Equipped with the first type of sidelink signaling radio bearer is used to transmit unprotected upper layer messages; the second type sidelink signaling radio bearer is used to transmit higher layer messages for establishing security for unicast links related to the sidelink communication; program.

[0129] This application claims priority based on Japanese Patent Application No. 2022-038087, filed on March 11, 2022, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0130] 1A, 1B UE 2. RAN Node 21 cells 41 AMF 44 PCF 61 V2X Application Server 103 Direct Interface between UEs 1403 Baseband Processor 1404 Application Processor 1406 memory 1407 Modules 1504 processor 1505 memory 1506 modules 1602 processor 1603 memory 1604 modules

Claims

1. means for conducting sidelink communications with a peer wireless terminal on a primary carrier and a secondary carrier; means for transmitting control plane data belonging to a sidelink signaling radio bearer of a first type and control plane data belonging to a sidelink signaling radio bearer of a second type, without using the secondary carrier, using the primary carrier; means for using the secondary carrier for transmitting user data belonging to a sidelink data radio bearer, but not using the secondary carrier for transmitting control plane data belonging to any sidelink signaling radio bearer; Equipped with the first type of sidelink signaling radio bearer is used for transmitting unprotected upper layer messages; the second type of sidelink signaling radio bearer is used to transmit higher layer messages for establishing security for a unicast link for the sidelink communication. Wireless terminal.

2. and means for using the primary carrier without using the secondary carrier for transmitting control plane data belonging to a sidelink signaling radio bearer of a third type. the third type of sidelink signaling radio bearer is used to transmit higher layer messages after the security is established. The wireless terminal of claim 1 .

3. and means for using the primary carrier without using the secondary carrier for transmitting control plane data belonging to a sidelink signaling radio bearer of a fourth type. the fourth type sidelink signaling radio bearer is used to transmit PC5 Radio Resource Control (PC5-RRC) messages after the security is established.

3. The wireless terminal of claim 2.

4. the primary carrier belongs to a licensed spectrum of a radio access network node to which the radio terminal is connected, and the secondary carrier belongs to an unlicensed spectrum; The wireless terminal according to any one of claims 1 to 3.

5. means for storing first setting parameters indicating a carrier frequency or a plurality of candidate carrier frequencies of the primary carrier and a carrier frequency or a plurality of candidate carrier frequencies of the secondary carrier; means for determining a carrier frequency of the primary carrier and a carrier frequency of the secondary carrier according to the first configuration parameters stored in the wireless terminal when the wireless terminal is out of coverage of a radio access network; The wireless terminal according to any one of claims 1 to 3.

6. configured to receive, when the wireless terminal is within the coverage of the radio access network, second configuration parameters indicating a carrier frequency of the primary carrier or a plurality of candidate carrier frequencies from the radio access network, and determine the carrier frequency of the primary carrier according to the second configuration parameters; 6. The wireless terminal according to claim 5.

7. and means for determining a carrier frequency of the secondary carrier according to the first configuration parameter when the wireless terminal is within the coverage of the radio access network.

7. The wireless terminal of claim 6.

8. conducting sidelink communications with a peer wireless terminal on a primary carrier and a secondary carrier; using the primary carrier without using the secondary carrier for transmitting control plane data belonging to a sidelink signaling radio bearer of a first type and control plane data belonging to a sidelink signaling radio bearer of a second type; and using the secondary carrier for transmitting user data belonging to a sidelink data radio bearer, but not using the secondary carrier for transmitting control plane data belonging to any sidelink signaling radio bearer; Equipped with the first type of sidelink signaling radio bearer is used for transmitting unprotected upper layer messages; the second type of sidelink signaling radio bearer is used to transmit higher layer messages for establishing security for a unicast link for the sidelink communication. A method performed by a wireless terminal.

9. A program for causing a computer to perform a method for a wireless terminal, comprising: The method comprises: conducting sidelink communications with a peer wireless terminal on a primary carrier and a secondary carrier; using the primary carrier without using the secondary carrier for transmitting control plane data belonging to a sidelink signaling radio bearer of a first type and control plane data belonging to a sidelink signaling radio bearer of a second type; and using the secondary carrier for transmitting user data belonging to a sidelink data radio bearer, but not using the secondary carrier for transmitting control plane data belonging to any sidelink signaling radio bearer; Equipped with the first type of sidelink signaling radio bearer is used for transmitting unprotected upper layer messages; the second type of sidelink signaling radio bearer is used to transmit higher layer messages for establishing security for a unicast link for the sidelink communication. program.

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