Patent Description:
To meet the increasing demand for wireless data traffic after the commercialization of <NUM>th Generation (<NUM>) communication system, efforts to develop an enhanced <NUM>th Generation (<NUM>) communication system or a pre-<NUM> communication system are continuing. For this reason, a <NUM> communication system or pre-<NUM> communication system is called a Beyond <NUM> Network communication system or a Post Long Term Evolution (LTE) system.

To achieve a high data transmission rate, the implementation of a <NUM> communication system in an ultra-high-frequency (mmWave) band (for example, a <NUM> band) is being considered. To reduce path loss of radio waves and increase a transfer distance of radio waves in an ultra-high-frequency band, in a <NUM> communication system, technologies for beamforming, massive Multiple Input Multiple Output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, analog beam-forming, and large-scale antenna are being discussed.

Also, to improve the network of the system, various technologies, such as evolved small cell, advanced small cell, cloud radio access network (cloud RAN), ultra-dense networks, Device to Device communication (D2D), wireless backhaul, moving networks, cooperative communication, Coordinated Multi-Points (CoMP), and interference cancellation, have been developed for <NUM> communication systems. In addition, other technologies, such as Hybrid frequency-shift keying (FSK) and quadrature amplitude modulation (QAM) Modulation (FQAM) and Sliding Window Superposition Coding (SWSC) based on Advanced Coding Modulation (ACM) and Non Orthogonal Multiple Access (NOMA) and Sparse Code Multiple Access (SCMA) based on Filter Bank Multi Carrier (FBMC), have been developed for <NUM> communication systems.

Meanwhile, the Internet is evolving from a human-centered network in which humans generate and consume information to an Internet of Things (IoT) network in which distributed components such as objects, transmit and receive information and process it. Internet of Everything (IoE) technology resulting from combining IoT technology with big data processing technology, etc. through a connection to a cloud server or the like is on the rise. To implement the IoT, various technical factors, such as sensing technology, wired/wireless communication, network infrastructure, service interface technology, and security technology, are required. Recently, technologies including a sensor network, Machine to Machine (M2M), and Machine Type Communication (MTC) for connections between objects have been studied.

In an IoT environment, an intelligent Internet Technology (IT) service is provided to collect and analyze data generated by connected objects to create new values for human life. The IoT may be applied to various fields, such as smart homes, smart buildings, smart cities, smart cars/connected cars, smart grids, health care, smart appliances, and advanced medical services, through convergence and combination between existing Information Technology (IT) and various industries.

Accordingly, various attempts to apply a <NUM> communication system to an IoT network are being made. For example, technologies, such as a sensor network, M2M, and MTC, are implemented by technologies, such as beam forming, MIMO, and array antenna, which are <NUM> communication technologies. Applying a cloud radio access network (CRAN) as big data processing technology also is an example of the convergence of <NUM> technology and IoT technology.

Vehicle to Everything (V2X) is a general term indicating all forms of communication methods that are applicable to vehicles on roads, and the V2X is combined with the development of wireless communication technologies to enable various additional services as well as initial safety use cases.

As technology providing a V2X service, a Wireless Access in Vehicular Environments (WAVE) standard based on IEEE <NUM>. 11p and IEEE P1609 has been standardized. However, WAVE, which is a kind of Dedicated Short Range Communication (DSRC) technology, has a limitation in that a message transmission distance between vehicles is restricted.

To overcome such a limitation, cellular-based V2X technology is being standardized by the <NUM>rd Generation Partnership Project (3GPP). In Release <NUM>/Release <NUM>, an Evolved Packet System (EPS) V2X standard based on an LTE system has been completed, and in Release <NUM>, standardization of <NUM>th Generation System (5GS) V2X based on a New Radio (NR) system is being conducted. "TS <NUM>: Identifiers for V2X communication over PC5" discusses identifiers for V2X communication over PC5. "TS <NUM> Procedure for PC5 unicast" discusses a procedure for PC5 unicast.

According to certain embodiments of this disclosure, a method, performed by a first user equipment (UE), of performing unicast communication includes transmitting a direct communication request message, generating a profile for a PC5 unicast link, receiving, from a second UE, a response message based on a result of establishment of the PC5 unicast link; and transmitting, to the second UE, a data message over the PC5 unicast link based on the response message, wherein the profile includes at least one of a Layer-<NUM> identifier (ID) of the first UE, an application layer ID of the first UE, a Layer-<NUM> ID of the second UE, an application layer ID of the second UE, PC5 <NUM>th generation (<NUM>) Quality of Service (QoS) Indicator (PQI), or PC5 QoS Flow identifier (PFI) associated with the PQI.

According to various embodiments, the Layer-<NUM> ID of the second UE and the Layer-<NUM> ID of the first UE may be used for initial signaling to establish the PC5 unicast link, and a destination Layer-<NUM> ID of the direct communication request message may be the Layer-<NUM> ID of the second UE.

The destination Layer-<NUM> ID may be equal to or different from Vehicle to Everything (V2X) service types.

The PFI may be assigned in a V2X layer of the first UE, and the V2X layer of the first UE may provide at least one of the data message, the PFI, or the PQI to an Access Stratum (AS) layer of the first UE.

In certain embodiments, the method may further include indicating, from a V2X layer to an AS layer, whether the direct communication request message or the response message is for signaling.

The method may further include changing at least one of the Layer-<NUM> ID of the first UE, the Layer-<NUM> ID of the second UE, the application layer ID of the first UE, or the application layer ID of the second UE.

The method may further include updating the profile based on update of a link layer identifier or a result of the changing of at least one of the Layer-<NUM> ID of the first UE, the Layer-<NUM> ID of the second UE, the application layer ID of the first UE, or the application layer ID of the second UE.

In various embodiments according to this disclosure, the direct communication request message may include first information about at least one of the PQI or the PFI, and the response message may include second information about at least one of the PQI or PFI.

According to certain embodiments of the disclosure, a first user equipment (UE) for performing unicast communication includes: a transceiver; and at least one processor coupled with the transceiver and configured to: transmit a direct communication request message based on a profile; determine a profile for a PC5 unicast link; receive, from a second UE, a response message based on a result of establishment of the PC5 unicast link; and transmit, to the second UE, a data message over the PC5 unicast link based on the response message, wherein the profile includes at least one of a Layer-<NUM> identifier (ID) of the first UE, an application layer ID of the first UE, a Layer-<NUM> ID of the second UE, an application layer ID of the second UE, PC5 <NUM>th generation (<NUM>) Quality of Service (QoS) Indicator (PQI), or PC5 QoS Flow identifier (PFI) associated with the PQI.

In some embodiments, the Layer-<NUM> ID of the second UE and the Layer-<NUM> ID of the first UE may be used for initial signaling to establish the PC5 unicast link, and a destination Layer-<NUM> ID of the direct communication request message may be the Layer-<NUM> ID of the second UE.

The at least one processor may be further configured to indicate, from a V2X layer to an AS layer, whether the direct communication request message or the response message is for signaling.

The at least one processor may be further configured to change at least one of the Layer-<NUM> ID of the first UE, the Layer-<NUM> ID of the second UE, the application layer ID of the first UE, or the application layer ID of the second UE.

According to some embodiments, the at least one processor may be further configured to update the profile based on update of a link layer identifier or a result of the change of at least one of the Layer-<NUM> ID, the application layer ID of the first UE, or the application layer ID of the second UE.

The direct communication request message may include first information about at least one of the PQI or the PFI, and the response message may include second information about at least one of the PQI or PFI.

Hereinafter, operational principles of the disclosure will be described in detail with reference to the accompanying drawings. However, when detailed descriptions about known functions or configurations associated with the disclosure are determined to unnecessarily obscure the gist of the disclosure, the detailed descriptions will be omitted. Although the following terms are defined in consideration of the functions of the disclosure, they may vary according to a user or operator's intentions, judicial precedents, etc. Hence, the terms must be defined based on the contents of the entire specification.

For the same reason, some components shown in the drawings may be exaggerated or schematically shown, or some components may be omitted. Also, the sizes of the components may not reflect actual sizes. In the drawings, the same or corresponding components are assigned like reference numerals.

Examples of a terminal may include a user equipment (UE), a mobile station (MS), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function.

As used in the present disclosure, the term controller encompasses a processor.

Advantages and features of the disclosure and a method for achieving them will be clear with reference to the accompanying drawings, in which embodiments are shown. Embodiments according to this disclosure may take many different forms and the scope of this disclosure should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that the disclosure will be thorough and complete, and will fully convey the concept of the disclosure to those of ordinary skill in the art, and the disclosure is only defined by the scope of the claims. Like reference numerals denote like elements throughout the specification.

It will be appreciated that the combinations of blocks and flowchart illustrations in the process flow diagrams may be performed by computer program instructions. These computer program instructions may be loaded into a processor of a general purpose computer, a special purpose computer, or other programmable data processing equipment, so that those instructions, which are executed through a processor of a computer or other programmable data processing equipment, create means for performing functions described in the flowchart block(s). These computer program instructions may also be stored in a computer usable or computer readable memory capable of directing a computer or other programmable data processing equipment to implement the functions in a particular manner so that the instructions stored in the computer usable or computer readable memory are also capable of producing manufacturing items containing instruction means for performing the functions described in the flowchart block(s). Computer program instructions may also be installed on a computer or other programmable data processing equipment so that a series of operating steps may be performed on a computer or other programmable data processing equipment to create a computer-executable process. Therefore, it is also possible for the instructions to operate the computer or other programmable data processing equipment to provide steps for executing the functions described in the flowchart block(s).

In addition, each block may represent a module, segment, or portion of code that includes one or more executable instructions for executing specified logical function(s). It should also be noted that in some alternative implementations, the functions mentioned in the blocks may occur out of order. For example, two blocks shown in succession may actually be executed substantially concurrently, or the blocks may sometimes be performed in reverse order according to the corresponding function.

As used herein, the terms 'portion', 'module', or 'unit' refers to a unit that can perform at least one function or operation, and may be implemented as a software or hardware component such as a Field Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC). However, the term 'portion', 'module' or 'unit' is not limited to software or hardware. The 'portion', 'module', or 'unit' may be configured in an addressable storage medium, or may be configured to run on at least one processor. Therefore, as an example, the 'portion', 'module', or 'unit' includes: components such as software components, object-oriented software components, class components, and task components; processors, functions, attributes, procedures, sub-routines, segments of program codes, drivers, firmware, microcodes, circuits, data, databases, data structures, tables, arrays, and variables. Functions provided in the components and 'portions', 'modules' or 'units' may be combined into a smaller number of components and 'portions', 'modules' and 'units', or sub-divided into additional components and 'portions', 'modules' or 'units'. Also, the components and 'portions', 'modules' or 'units' may be configured to run on one or more Central Processing Units (CPUs) in a device or a security multimedia card. Also, in the embodiments, the 'portion', 'module' or 'unit' may include one or more processors.

As used herein, terms indicating connection nodes, terms indicating network entities, terms indicating messages, terms indicating interfaces between the network entities, terms indicating various identification information, etc. are examples for convenience of description. Accordingly, the disclosure is not limited to the terms, and other terms having the equivalent technical meanings may be used.

Hereinafter, for convenience of description, terms and names defined in standards for <NUM>th Generation (<NUM>), New Radio (NR), and a Long Term Evolution (LTE) system are used in the disclosure. However, the disclosure is not limited by terms and names, and may be applied in the same way to system based on other standards.

The detailed descriptions of embodiments of the disclosure may be provided with reference to terms and concepts set forth in one or more communication standards defined by the <NUM>rd Generation Partnership Project (3GPP). However, embodiments according to this disclosure may be practiced in other communication systems having similar technical backgrounds through slight modifications consistent with the instant disclosure, as informed by the technical knowledge of a person of ordinary skill in the technical art to which the disclosure pertains.

The detailed descriptions of the embodiments of the disclosure are in certain cases, described with reference to a vehicle communication service. However, the embodiments according to this disclosure are not limited by the choice of explanatory examples herein and the disclosure may be applied to other services that are provided on a <NUM> network.

A <NUM> system supports various services of a <NUM> system. For example, representative services include an enhanced mobile broad band (eMBB), ultra-reliable and low latency communication (URLLC), massive machine type communication (mMTC), and evolved multimedia broadcast/multicast Service (eMBMS). A system providing a URLLC service is called a URLLC system, and a system providing an eMBB service is called eMBB system. Also, the terms 'service' and 'system' may be used interchangeably.

The URLLC service has not been considered in the <NUM> system and is newly considered in the <NUM> system. The URLLC service requires conditions of ultra high-reliability (for example, a packet error rate of about <NUM>-<NUM>) and low latency (for example, about <NUM> msec) compared to other services. To meet such strict requirements, the URLLC service may need application of a transmission time interval (TTI) that is shorter than the eMBB service, and various operation methods using the URLLC service are considered.

Meanwhile, the Internet is evolving from a human-centered network on which humans generate and consume information to an Internet of Things (IoT) network on which distributed components such as objects information transmit and receive information and process it. Internet of Everything (IoE) technology resulting from combining IoT technology with big data processing technology, etc. through a connection to a cloud server or the like is on the rise. To implement the IoT, various technical factors, such as sensing technology, wired/wireless communication, network infrastructure, service interface technology, and security technology, are required. Recently, technologies including a sensor network, Machine to Machine (M2M), and Machine Type Communication (MTC) for connections between objects are being studied.

<FIG> illustrates an example of a configuration of a vehicle communication system according to certain embodiments of the disclosure.

Referring to the non-limiting example of <FIG>, a user equipment (UE) (which, according to this disclosure, encompasses, without limitation, a user terminal, a terminal, or a vehicle user equipment) <NUM> may communicate with another user equipment <NUM> by using direct communication (for example, Device-to-Device (D2D), ProSe, PC5, and Sidelink communication) <NUM> or network communication <NUM> and <NUM> through a mobile communication system <NUM>. In the direct communication <NUM>, message transmission/reception between the user equipment <NUM> and the other user equipment <NUM> may be conducted through a PC5 link. In the network communication <NUM> and <NUM>, a message that will be sent from a transmission vehicle user equipment to reception a vehicle user equipment may be transmitted to a network through a Uu link and then transmitted to the reception vehicle user equipment through the Uu link. The mobile communication system <NUM> may be an Evolved Packet Core (EPC) system or a <NUM>th Generation Core (5GC) system defined in the 3GPP, or another communication system than the 3GPP. The direct communication <NUM> may be provided by using Long Term Evolution Radio Access Technology (LTE RAT), NR RAT, or non-3gpp RAT such as Wireless Fidelity (WiFi).

<FIG> illustrates an example of control plane protocol stacks of a user equipment according to certain embodiments of the disclosure. <FIG> illustrates an example user plane protocol stacks of a user equipment according to certain embodiments of the disclosure. Referring to the non-limiting example of <FIG>, the user equipment <NUM> may be a transmission user equipment, and the user equipment <NUM> may be a reception user equipment. However, for convenience of description, the transmission user equipment and the reception user equipment will be referred to as the user equipment <NUM> and the user equipment <NUM>, respectively.

Referring to the illustrative example of <FIG>, control plane protocol stacks of the user equipment <NUM> and <NUM> may be composed of PC5 Signalling Protocol layers <NUM> and <NUM>, RRC layers <NUM> and <NUM>, PDCP layers <NUM> and <NUM>, RLC layers <NUM> and <NUM>, MAC layers <NUM> and <NUM>, and PHY layers <NUM> and <NUM>. The RRC layers <NUM> and <NUM>, the PDCP layers <NUM> and <NUM>, the RLC layers <NUM> and <NUM>, and the MAC layers <NUM> and <NUM> are collectively referred to as Access Stratum layers.

The PC5 Signalling Protocol layers <NUM> and <NUM> may provide a function of link establishment and link maintenance for the direct communication <NUM> between the user equipment <NUM> and the user equipment <NUM>.

Referring to the non-limiting example of <FIG>, user plane protocol stacks of the user equipment <NUM> and <NUM> may be composed of Application layers <NUM> and <NUM>, Service Enabling (SE) layers <NUM> and <NUM>, SDAP layers <NUM> and <NUM>, PDCP layers <NUM> and <NUM>, RLC layers <NUM> and <NUM>, MAC layers <NUM> and <NUM>, and PHY layers <NUM> and <NUM>. The SDAP layers <NUM> and <NUM>, the PDCP layers <NUM> and <NUM>, the RLC layers <NUM> and <NUM>, and the MAC layers <NUM> and <NUM> are collectively referred to as Access Stratum (AS) layers.

In certain embodiments, SE layers <NUM> and <NUM> may be intermediate layers for performing operations of the application layers <NUM> and <NUM>, and provide a function specialized for each application or service. A SE layer may support a plurality of application layers. Also, a SE layer specialized for each application layer may be defined. For example, to provide a V2X service, the application layers <NUM> and <NUM> may be V2X application layers. Also, to perform operations of the V2X application layers, the SE layers <NUM> and <NUM> may be defined as V2X layers. Hereinafter, to provide a V2X service, the application layers <NUM> and <NUM> may be interchangeable with V2X application layers, and the SE layers <NUM> and <NUM> may be interchangeable with V2X layers.

The SE layers <NUM> and <NUM> may provide a data transfer function on a link established for the direct communication <NUM> between the user equipment <NUM> and the user equipment <NUM>. The SE layers <NUM> and <NUM> may include an internet protocol (IP), a non-IP, and a transport protocol (for example, a transmission control protocol (TCP) or a user datagram protocol (UDP)) to transmit messages.

The user equipment <NUM> and <NUM> according to certain embodiments of the disclosure may acquire information shown in Table <NUM> from a network through a procedure shown in <FIG>, and store the information to use the V2X service. The SE layers <NUM> and <NUM> may use the stored information.

The SDAP layers <NUM> and <NUM> may be, after a link for the direct communication <NUM> between the user equipment <NUM> and the user equipment <NUM> is established, used to transmit data on the established link. For example, when a link for the direct communication <NUM> between the user equipment <NUM> and the user equipment <NUM> is established and then data is transmitted on the established link (for example, PC5 unicast communication or PC5 group cast), the SDAP layers <NUM> and <NUM> may be used for message transmission. Also, when data is transmitted without establishing a link for the direct communication <NUM> between the user equipment <NUM> and the user equipment <NUM> (for example, PC5 broadcast communication), the SDAP layers <NUM> and <NUM> may be not used for message transmission.

The PC5 signalling protocol layers <NUM> and <NUM> according to certain embodiments of the disclosure may include a function that is provided by the SE layers <NUM> and <NUM>. Alternatively, the PC5 signalling protocol layers <NUM> and <NUM> may interact with the SE layers <NUM> and <NUM> for link establishment and/or link maintenance.

<FIG> illustrates an example of a procedure for direct communication link establishment (ProSe link establishment) according to certain embodiments of the disclosure.

Referring to the non-limiting example of <FIG>, to perform a procedure for direct communication link establishment, user equipments <NUM>, <NUM>, <NUM>, and <NUM> may acquire destination layer-<NUM> ID (corresponding to 'The destination Layer-<NUM> ID for PC5 unicast link establishment' of Table <NUM>) information for link establishment from a network by using procedures shown in <FIG>, <FIG>, and <FIG>, and store the destination layer-<NUM> ID information. The destination layer-<NUM> ID for link establishment may be set to different values according to application layers, applications that are supported by the application layers, or message types that are supported by the application layers. Alternatively, the destination layer-<NUM> ID for link establishment may be set to a value regardless of application layers, applications that are supported by the application layers, or message types that are supported by the application layers.

Referring to the illustrative example of <FIG>, the user equipment <NUM>, <NUM>, and <NUM> may determine a destination layer-<NUM> ID (corresponding to 'The destination Layer-<NUM> ID for PC5 unicast link establishment' of Table <NUM>) for link establishment among stored V2X service policy parameters (information shown in Table <NUM>) to receive an establishment signaling message of a direct communication link. When the user equipment <NUM>, <NUM>, and <NUM> receive an establishment signaling message for a direct communication link having the destination layer-<NUM> ID for link establishment as a destination, the user equipment <NUM>, <NUM>, and <NUM> may process the establishment signaling message, in operation <NUM>. The establishment signaling message of the direct communication link may have an address of the destination layer-<NUM> ID as a destination.

The application layer <NUM> of the user equipment <NUM> which wants to perform an application operation may provide at least one of an 'application message' (hereinafter, referred to as a 'message' and being interchangeable with 'service data', 'data' or 'application data') generated by the application layer <NUM>, a 'message type' (being interchangeable with a 'service type') representing a type of the message, a 'communication mode' (for example, Broadcast, Groupcast, Unicast, etc.) representing a communication method of the message, an 'application layer ID' (application layer identifier) of the user equipment <NUM>, an 'application layer ID' (application layer identifier) of the user equipment <NUM>, or 'Quality of Service (QoS) requirements' to the SE layer <NUM>, in operation <NUM>. In vehicle communication, the message type may be PSID, ITS-AID, etc..

The SE layer <NUM> of the user equipment <NUM> may determine whether to perform a link establishment procedure, based on communication mode information received from the application layer <NUM>, in operation <NUM>. For example, when a communication mode received from the application layer <NUM> is PC5 unicast, the SE layer <NUM> may determine to perform a link establishment procedure, and perform the following operation, in operation <NUM>.

The SE layer <NUM> of the user equipment <NUM> may assign a flow identifier (ID) (being interchangeable with a QoS Flow Identifier (QFI) or a PC5 Flow Identifier (PFI), and hereinafter, referred to as a PFI) for generating a unicast link. The PFI may be assigned as a unique value in the user equipment <NUM>. The SE layer <NUM> may transform the QoS requirements received from the application layer <NUM> into PQI (PCS SQI) information capable of being used in the AS layer. Also, the SE layer <NUM> may determine whether the PQI information is available based on the V2X service policy parameters (for example, 'The list of V2X services that are allowed to use a specific PQI(s)' of Table <NUM>) information. For example, the V2X service policy parameters (for example, 'The list of V2X services that are allowed to use a specific PQI(s)' of Table <NUM>) may include a list of V2X services that are allowed to use high QoS (PQI), and the V2X services included in the list of V2X services are allowed to use a high PQI value.

The SE layer <NUM> generates a direct communication request message for unicast link establishment. The direct communication request message may include at least one of an 'application message', a 'message type', an 'application layer ID' of the user equipment <NUM>, 'QoS requirements', a 'PQI', or a 'PFI'.

The SE layer <NUM> may itself assign a layer-<NUM> ID of the user equipment <NUM>, which is to be used for a PC5 unicast link to be generated, and set the layer-<NUM> ID assigned by the user equipment <NUM> to a source layer-<NUM> ID of the direct communication request message. The SE layer <NUM> may set a stored destination layer-<NUM> ID address ('The destination Layer-<NUM> ID for PC5 unicast link establishment' of Table <NUM>) for link establishment to a destination layer-<NUM> ID of the direct communication request message.

In various embodiments, SE layer <NUM> may generate a link profile (being interchangeable with a unicast link profile, a PC5 link profile, or a PC5 unicast link profile) for the PC5 unicast link to be established. The link profile may include at least one of an 'application layer ID' of the user equipment <NUM>, an 'application layer ID' of the user equipment <NUM>, a 'layer-<NUM> ID' of the user equipment <NUM> assigned by the user equipment <NUM>, 'QoS requirements', a 'PQI', or 'PFI' information, and may be identified as a PFI which is a unique value in the user equipment <NUM>.

The SE layer <NUM> may transmit the direct communication request message, the source layer-<NUM> ID (that is, the layer-<NUM> ID of the user equipment <NUM> assigned by the SE layer <NUM>) of the direct communication request message, the destination layer-<NUM> ID (that is, the destination layer-<NUM> ID address for link establishment stored in the user equipment <NUM>) of the direct communication request message, and information (for example, the assigned PFI information) of the direct communication link to be established to the PDCP layer <NUM>. The SE layer <NUM> may indicate, to the PDCP layer <NUM>, that a communication mode of the direct communication request message is PC5 broadcast. The user equipment <NUM> may transmit, by using a broadcast scheme, the direct communication request message via the PDCP layer <NUM>, the RLC layer <NUM>, the MAC layer <NUM>, and the PHY layer <NUM>, in operation <NUM>.

The user equipments <NUM>, <NUM>, and <NUM> located in a vicinity of the user equipment <NUM> may receive the direct communication request message transmitted from the user equipment <NUM>, in operation <NUM>. Each of the user equipments <NUM>, <NUM>, and <NUM> may transfer the direct communication request message to a SE layer via a PHY layer, a MAC layer, a RLC layer, and a PDCP layer of each of the user equipments <NUM>, <NUM>, and <NUM>. The SE layer may receive the direct communication request message, check a destination address of the direct communication request message, and determine a processing method of the direct communication request message. When the destination address of the direct communication request message is the destination layer-<NUM> ID address (see operation <NUM>) for link establishment stored in the corresponding user equipment, the SE layer may select an application layer to which the direct communication request message is to be transferred, based on at least one of the destination layer-<NUM> ID address of the direct communication request message, the 'message type' included in the direct communication request message, or the 'application layer ID' information of the user equipment included in the direct communication request message, and transfer the direct communication request message to the selected application layer.

When the application layer <NUM> of the user equipment <NUM> receives the direct communication request message, the application layer <NUM> may determine to respond to the direct communication request message, based on the 'application message', the 'message type', the 'application layer ID' of the user equipment <NUM>, the 'application layer ID' of the user equipment <NUM>, etc., included in the direct communication request message. When the application layer <NUM> of the user equipment <NUM> determines to approve the direct communication request, the application layer <NUM> may provide at least one of an 'application message' (hereinafter, referred to as a 'message') generated by the application layer <NUM>, a 'message type' representing a type of the message, a 'communication mode' (for example, broadcast, groupcast, unicast, etc.) representing a communication method of the message, an 'application layer ID' of the user equipment <NUM>, an 'application layer ID' of the user equipment <NUM>, or 'QoS requirements' to the SE layer <NUM>, in operation <NUM>.

The SE layer <NUM> of the user equipment <NUM> may determine to perform a link establishment procedure, and perform the following operation, in operation <NUM>.

The SE layer <NUM> of the user equipment <NUM> may assign a PFI for generating a unicast link, or use the PFI received in operation <NUM>. The PFI may be assigned as a unique value in the user equipment <NUM>. The SE layer <NUM> may transform the QoS requirements received from the application layer <NUM> into PQI (PC5 5QI) information capable of being used in an AS layer.

The SE layer <NUM> of the user equipment <NUM> may generate a direct communication response message for unicast link establishment. The direct communication response message may include at least one of an 'application message', a 'message type', an 'application layer ID' of the user equipment <NUM>, an 'application layer ID' of the user equipment <NUM>, 'QoS requirements', a 'PQI', or a 'PFI'.

The SE layer <NUM> of the user equipment <NUM> may itself assign a layer-<NUM> ID of the user equipment <NUM> to be used for a PC5 unicast link to be generated, and set the layer-<NUM> ID assigned by the user equipment <NUM> to a source layer-<NUM> ID of the direct communication response message. The SE layer <NUM> may set the source layer-<NUM> ID of the direct communication request message received in operation <NUM> to a destination layer-<NUM> ID of the direct communication response message.

The SE layer <NUM> of the user equipment <NUM> may generate a link profile (also, being interchangeable with a unicast link profile, a PC5 link profile, or a PC5 unicast link profile) for the PC5 unicast link to be established. The link profile may include at least one of the 'application layer ID' and 'layer-<NUM> ID' (that is, the source layer-<NUM> ID of the direct communication request message received in operation <NUM>) of the user equipment <NUM>, the 'application layer ID' and 'layer-<NUM> ID' (assigned by the user equipment <NUM>) of the user equipment <NUM>, 'QoS requirements', a 'PQI', or 'PFI' information, and the link profile may be identified as a PFI which is a unique value in the user equipment <NUM>.

The SE layer <NUM> may transmit the direct communication response message, the source layer-<NUM> ID (that is, the layer-<NUM> ID of the user equipment <NUM> assigned by the SE layer <NUM>) of the direct communication response message, the destination layer-<NUM> ID (that is, the source layer-<NUM> ID of the direct communication request message received in operation <NUM>) of the direct communication response message, and information (for example, information about the assigned PFI) about the direct communication link to be established to the PDCP layer <NUM> or the RRC layer <NUM>. At this time, the SE layer <NUM> may indicate the PDCP layer <NUM> or the RRC layer <NUM> to configure a communication mode of the direct communication response message to PC5 unicast, and a message type to signaling. When the SE layer <NUM> transmits the direct communication response message through the RRC layer <NUM>, the direct communication response message may be included in a RRC message and transmitted to the user equipment <NUM>. The MAC layer <NUM> of the user equipment <NUM> may configure a logical channel ID (LCID) of a MAC header for transmitting the direct communication response message with a value representing a signaling message. The direct communication response message may be transmitted to the user equipment <NUM> via the PHY layer <NUM>, in operation <NUM>.

In various embodiments according to this disclosure, the SE layer <NUM> of the user equipment <NUM> receives the direct communication response message, the SE layer <NUM> notifies the application layer <NUM> that a direct communication link has been established. At this time, the SE layer <NUM> of the user equipment <NUM> may notify the application layer <NUM> of information (for example, a PFI, etc.) related to the direct communication link, together. Also, the SE layer <NUM> may notify the PDCP layer <NUM> or the RRC layer <NUM> of the information (for example, information about the assigned PFI) related to the direct communication link that has been completely established. The SE layer <NUM> may update the link profile generated in operation <NUM>, based on the direct communication response message. For example, the SE layer <NUM> may store the destination layer-<NUM> ID of the direct communication response message received in operation <NUM> as a 'layer-<NUM> ID' of the user equipment <NUM>. Also, when the 'application layer ID' of the user equipment <NUM>, the 'QoS requirements', the 'PQI', and the 'PFI' information included in the direct communication response message received in operation <NUM> do not match with the link profile generated in operation <NUM>, the SE layer <NUM> may update the link profile to information received in operation <NUM>.

<FIG> illustrates an example of a procedure of changing a user equipment identifier, according to certain embodiments of the disclosure. More specifically, <FIG> illustrates, without limitation, a procedure of changing a layer-<NUM> ID, according to certain embodiments of the disclosure.

Referring to the non-limiting example of <FIG>, the user equipment <NUM> and the user equipment <NUM> may complete direct communication link establishment through the above-described procedure for direct communication link establishment. The user equipments <NUM> and <NUM> may generate a link profile during a process of direct communication link establishment, and store layer-<NUM> ID information of the user equipments <NUM> and <NUM>, which is to be used for a direct communication link.

The user equipment <NUM> may determine a layer-<NUM> ID address of the user equipment <NUM> among stored link profile information to receive a direct communication link maintenance signaling message, in operation <NUM>. The direct communication link maintenance signaling message may have, as a destination, the layer-<NUM> ID address of the user equipment <NUM> determined in operation <NUM>.

In some embodiments, application layer <NUM> of the user equipment <NUM> may change a currently used application layer ID of the user equipment <NUM>. The application layer <NUM> may transfer the changed application layer ID and direct communication link information (for example, a service type (e.g., PSID or ITS-AIDs), a PFI, etc.) in which the application layer ID is used to the SE layer <NUM>, in operation <NUM>.

When the SE layer <NUM> receives the changed application layer ID from the application layer in operation <NUM> or when a service type being currently used by the user equipment <NUM> based on a policy/parameter stored in the user equipment <NUM> requests a privacy support, the SE layer <NUM> may determine to perform a procedure of changing the layer-<NUM> ID at regular time intervals, and perform the following operation, in operation <NUM>.

The SE layer <NUM> of the user equipment <NUM> may itself assign a new layer-<NUM> ID of the user equipment <NUM>, which is to be newly used in the direct communication link associated with the PFI. The SE layer <NUM> may store the new layer-<NUM> ID of the user equipment <NUM> in a link profile associated with the PFI. When the SE layer <NUM> receives a newly assigned application layer ID from the application layer <NUM> in operation <NUM>, the SE layer <NUM> may store the newly assigned application layer ID of the user equipment <NUM> in the link profile associated with the PFI.

In some embodiments, the SE layer <NUM> may generate a link layer identifier update request message for changing the layer-<NUM> ID. The link layer identifier update request message may include at least one of the newly assigned layer-<NUM> ID of the user equipment <NUM>, the newly assigned application layer ID (when the SE layer <NUM> receives the newly assigned application layer ID from the application layer <NUM> in operation <NUM>) of the user equipment <NUM>, the layer-<NUM> ID previously used by the user equipment <NUM>, the application layer ID previously used or being currently used by the user equipment <NUM>, or the 'PFI' representing the corresponding direct communication link.

The SE layer <NUM> of the user equipment <NUM> may set a source layer-<NUM> ID of the link layer identifier update request message to the previously used layer-<NUM> ID of the user equipment <NUM> or the newly assigned layer-<NUM> ID of the user equipment <NUM>. Also, the SE layer <NUM> of the user equipment <NUM> may set a destination layer-<NUM> ID of the link layer identifier update request message to the layer-<NUM> ID of the user equipment <NUM>, stored in the link profile associated with the PFI.

The SE layer <NUM> may transmit the link layer identifier update request message, the source layer-<NUM> ID of the link layer identifier update request message, the destination layer-<NUM> ID of the link layer identifier update request message, and PFI information related to the link layer identifier update request message to the RRC layer <NUM>. At this time, the SE layer <NUM> may indicate PC5 unicast as a communication mode of the link layer identifier update request message and signaling as a message type to the RRC layer <NUM>. The link layer identifier update request message may be included in a RRC message and transmitted to the user equipment <NUM>. The MAC layer <NUM> of the user equipment <NUM> may set a logical channel ID of the MAC header for transmitting the link layer identifier update request message to a value representing a signaling message. A value of a logical channel ID used in a signaling message may be different from that of a logical channel ID used in a data message. The link layer identifier update request message may be transmitted to the user equipment <NUM> via the PHY layer <NUM>, in operation <NUM>.

When the MAC layer <NUM> of the user equipment <NUM> receives the link layer identifier update request message, the MAC layer <NUM> may check the logical channel ID of the MAC header of the link layer identifier update request message to determine that the link layer identifier update request message is a signaling message, and transfer the link layer identifier update request message to the SE layer <NUM> via the RRC layer <NUM>. The SE layer <NUM> may check the destination layer-<NUM> ID and/or the PFI information of the link layer identifier update request message to determine that the link layer identifier update request message is a message for the direct communication link generated by the above-described procedure. Also, the SE layer <NUM> of the user equipment <NUM> may determine that the received link layer identifier update request message is a signaling message depending on whether the link layer identifier update request message is received from the RRC layer <NUM>, and perform the following operation, in operation <NUM>.

The SE layer <NUM> may update link profile information based on information of the received link layer identifier update request message. For example, the SE layer <NUM> of the user equipment <NUM> may check the PFI included in the link layer identifier update request message, and store the newly assigned layer-<NUM> ID of the user equipment <NUM>, included in the link layer identifier update request message, in a link profile associated with the PFI and stored in the user equipment <NUM>. When the newly assigned application layer ID is included in the link layer identifier update request message, the SE layer <NUM> may store the newly assigned application layer ID of the user equipment <NUM>, included in the link layer identifier update request message, in the link profile associated with the PFI, and then notify the application layer <NUM> that the application layer ID of the user equipment <NUM> for direct communication link establishment has changed. At this time, the SE layer <NUM> of the user equipment <NUM> may notify the application layer <NUM> of information (for example, PFI, etc.) related to the direct communication link, together.

In various embodiments according to this disclosure, SE layer <NUM> of the user equipment <NUM> may generate a link layer identifier update response message. The link layer identifier update response message may include at least one of information notifying that the user equipment <NUM> has received the link layer identifier update request message and will use the newly assigned layer-<NUM> ID and/or the newly assigned application layer ID of the user equipment <NUM> for subsequent direct communication, or the PFI used in the corresponding direct communication link.

When the user equipment <NUM> determines to change an ID that the user equipment <NUM> uses, the SE layer <NUM> may itself assign a new layer-<NUM> ID of the user equipment <NUM>, and include the new layer-<NUM> ID of the user equipment <NUM> in the link layer identifier update response message. Also, when the SE layer <NUM> receives a new application layer ID from the application layer <NUM>, the SE layer <NUM> may include the new application layer ID of the user equipment <NUM> in the link layer identifier update response message. The SE layer <NUM> may store the new layer-<NUM> ID and/or the new application layer ID of the user equipment <NUM> in the link profile associated with the PFI.

The SE layer <NUM> of the user equipment <NUM> may set a source layer-<NUM> ID of the link layer identifier update response message to the currently used new layer-<NUM> ID of the user equipment <NUM>, stored in the link profile associated with the PFI. Also, the SE layer <NUM> of the user equipment <NUM> may set a destination layer-<NUM> ID of the link layer identifier update response message to the currently used new layer-<NUM> ID of the user equipment <NUM>, stored in the link profile associated with the PFI.

The SE layer <NUM> may transmit the link layer identifier update response message, the source layer-<NUM> ID of the link layer identifier update response message, the destination layer-<NUM> ID of the link layer identifier update response message, and PFI information associated with the link layer identifier update response message to the RRC layer <NUM>. At this time, the SE layer <NUM> may indicate the RRC layer <NUM> to configure a communication mode of the link layer identifier update response message to PC5 unicast, and a message type to signaling. The link layer identifier update response message may be included in a RRC message and transmitted to the user equipment <NUM>. The MMC layer <NUM> of the user equipment <NUM> may set a logical channel ID of the MAC header for transmitting the link layer identifier update response message to a value representing a signaling message. A value of a logical channel ID used in a signaling message may be different from that of a logical channel ID used in a data message. The link layer identifier update response message may be transmitted to the user equipment <NUM> via the PHY layer <NUM>, in operation <NUM>.

The user equipment <NUM> may use the new IDs (the new layer-<NUM> ID and/or the new application layer ID of the user equipment <NUM> and the new layer-<NUM> ID and/or the new application layer ID of the user equipment <NUM>) of the user equipments <NUM> and <NUM> for subsequent direct communication (signaling and message transmission) associated with the PFI.

When the MAC layer <NUM> of the user equipment <NUM> receives the link layer identifier update response message, the MAC layer <NUM> of the user equipment <NUM> may check the logical channel ID of the MAC header of the link layer identifier update response message to determine that the received link layer identifier update response message is a signaling message, and transfer the link layer identifier update response message to the SE layer <NUM> via the RRC layer <NUM>. The SE layer <NUM> may determine whether the link layer identifier update response message is a message for the direct communication link generated by the above-described procedure, based on the destination layer-<NUM> ID of the received link layer identifier update response message and/or the PFI information. Also, the SE layer <NUM> of the user equipment <NUM> may determine that the received link layer identifier update response message is a signaling message, depending on whether the link layer identifier update response message is received from the RRC layer <NUM>. The SE layer <NUM> may use the new IDs (for example, the new layer-<NUM> ID and/or the new application layer ID of the user equipment <NUM> and the new layer-<NUM> ID and/or the new application layer ID of the user equipment <NUM>) of the user equipments <NUM> and <NUM> for signaling and message transmission for direct communication associated with the PFI. When the user equipment <NUM> includes new ID information (for example, the new layer-<NUM> ID and/or the new application layer ID of the user equipment <NUM>) in the link layer identifier update response message, the SE layer <NUM> may store the new ID information of the user equipment <NUM> in the link profile associated with the PFI.

The user equipments <NUM> and <NUM> may update a QoS parameter (for example, PQI) that is used for direct communication associated with the PFI by a method that is similar to the procedure shown in <FIG>. To update the QoS parameter, the link layer identifier update request message or the link layer identifier update response message may be used as a signaling message. Another signaling message (for example, a QoS parameter update request message or a QoS parameter update response message) or a signaling message (for example, a Prose Link Update request/response message) capable of being used for both ID updating and QoS parameter updating of a user equipment may be used as a signaling message.

<FIG> illustrates an example of a procedure of releasing a direct communication link, according to certain embodiments of the disclosure.

Referring to the non-limiting example of <FIG>, the user equipment <NUM> and the user equipment <NUM> may complete direct communication link establishment through the above-described procedure. The user equipments <NUM> and <NUM> may generate a link profile during a process of direct communication link establishment, and store layer-<NUM> ID information of the user equipments <NUM> and <NUM>, which is to be used for the direct communication link.

The user equipment <NUM> may determine a layer-<NUM> ID address of the user equipment <NUM> from among stored link profile information to receive a direct communication link maintenance signaling message, in operation <NUM>. The direct communication link maintenance signaling message may have, as a destination, the layer-<NUM> ID address of the user equipment <NUM> determined in operation <NUM>.

The application layer <NUM> of the user equipment <NUM> may make a request to release a direct communication link associated with a PFI, in operation <NUM>.

The SE layer <NUM> of the user equipment <NUM> may perform the following operation to release the direct communication link, in operation <NUM>.

The SE layer <NUM> may generate a direct communication release request message. The SE layer <NUM> of the user equipment <NUM> may set a source layer-<NUM> ID of the direct communication release request message to the currently used layer-<NUM> ID of the user equipment <NUM>, stored in a link profile associated with the PFI. Also, the SE layer <NUM> may set a destination layer-<NUM> ID of the direct communication release request message to the currently used layer-<NUM> ID of the user equipment <NUM>, stored in the link profile associated with the PFI.

The SE layer <NUM> may transmit the direct communication release request message, the source layer-<NUM> ID of the direct communication release request message, the destination layer-<NUM> ID of the direct communication release request message, and PFI information associated with the direct communication release request message to the RRC layer <NUM>. At this time, the SE layer <NUM> may indicate the RRC layer <NUM> to configure a communication mode of the direct communication release request message to PC5 unicast, and a message type to signaling. The direct communication release request message may be included in a RRC message and transmitted to the user equipment <NUM>. The MAC layer <NUM> of the user equipment <NUM> may set a logical channel ID of a MAC header for transmitting the direct communication release request message to a value representing a signaling message. A value of a logical channel ID used in a signaling message may be different from that of a logical channel ID used in a data message. The direct communication release request message may be transmitted to the user equipment <NUM> via the PHY layer <NUM>, in operation <NUM>.

In various embodiments, when the MAC layer <NUM> of the user equipment <NUM> receives the direct communication release request message, the MAC layer <NUM> may determine whether the direct communication release request message is a signaling message, based on the logical channel ID of the MAC header of the direct communication release request message, and transfer the direct communication release request message to the SE layer <NUM> via the RRC layer <NUM>. The SE layer <NUM> may determine whether the direct communication release request message is a message for a direct communication link, based on the destination layer-<NUM> ID of the direct communication release request message and/or the PFI information. Also, the SE layer <NUM> of the user equipment <NUM> may determine that the direct communication release request message is a signaling message, depending on whether the direct communication release request message is received from the RRC layer <NUM>, and perform the following operation, in operation <NUM>.

The SE layer <NUM> may notify the application layer <NUM> that the direct communication link associated with the PFI has been released. The SE layer <NUM> may generate a direct communication release response message. The SE layer <NUM> of the user equipment <NUM> may set a source layer-<NUM> ID of the direct communication release response message to the currently used layer-<NUM> ID of the user equipment <NUM>, stored in a link profile associated with the PFI. Also, the SE layer <NUM> may set a destination layer-<NUM> ID of the direct communication release response message to the currently used layer-<NUM> ID of the user equipment <NUM>, stored in the link profile associated with the PFI.

In various embodiments, the SE layer <NUM> may transmit the direct communication release response message, the source layer-<NUM> ID of the direct communication release response message, the destination layer-<NUM> ID of the direct communication release response message, and PFI information associated with the direct communication release response message to the RRC layer <NUM>. At this time, the SE layer <NUM> may indicate the RRC layer <NUM> to configure a communication mode of the direct communication release response message to PC5 unicast, and a message type to signaling. The direct communication release response message may be included in a RRC message and transmitted to the user equipment <NUM>. The MAC layer <NUM> of the user equipment <NUM> may set a logical channel ID of a MAC header for transmitting the direct communication release response message to a value representing a signaling message. A value of a logical channel ID used in a signaling message may be different from that of a logical channel ID used in a data message. The direct communication release response message may be transmitted to the user equipment <NUM> via the PHY layer <NUM>, in operation <NUM>.

The SE layer <NUM> may delete the link profile information associated with the PFI.

When the MAC layer <NUM> of the user equipment <NUM> receives the direct communication release response message, the MAC layer <NUM> may determine whether the direct communication release response message is a signaling message, based on the logical channel ID of the MAC header of the direct communication release response message, and transfer the direct communication release response message to the SE layer <NUM> via the RRC layer <NUM>. The SE layer <NUM> may determine whether the direct communication release response message is a message for the direct communication link generated by the above-described procedure, based on the destination layer-<NUM> ID of the direct communication release response message and/or the PFI information. Also, the SE layer <NUM> of the user equipment <NUM> may determine that the direct communication release response message is a signaling message, depending on whether the direct communication release response message is received from the RRC layer <NUM>. The SE layer <NUM> may notify the application layer <NUM> that the direct communication link associated with the PFI has been released. The SE layer <NUM> may delete the link profile information associated with the PFI.

<FIG> illustrates an example of a procedure of releasing a direct communication link, according to various embodiments of the disclosure.

Referring to the non-limiting example of <FIG>, the user equipment <NUM> and the user equipment <NUM> may complete direct communication link establishment through the above-described procedure. The user equipments <NUM> and <NUM> may generate a link profile during a process of direct communication link establishment, and store layer-<NUM> ID information of the user equipments <NUM> and <NUM>, which is to be used for a direct communication link.

The SE layers <NUM> and <NUM> of the user equipments <NUM> and <NUM> may check current state information of a direct communication link associated with a PFI by the following method, in operation <NUM>.

First, the SE layers <NUM> and <NUM> may receive a report about the current state information of the direct communication link associated with the PFI from the RRC layers <NUM> and <NUM>, the PDCP layers <NUM> and <NUM>, the RLC layers <NUM> and <NUM>, or the MAC layers <NUM> and <NUM>. When the received report about the current state information represents a link failure, the SE layers <NUM> and <NUM> may determine that a communication through the direct communication link established between the user equipments <NUM> and <NUM> is currently impossible.

Alternatively, the SE layers <NUM> and <NUM> may use a Keep-alive function. When there is no response to a Keep-alive request message from the user equipments <NUM> and <NUM> for a preset time period, the SE layers <NUM> and <NUM> may determine that a communication through the direct communication link established between the user equipments <NUM> and <NUM> is currently impossible.

When the SE layers <NUM> and <NUM> may determine that a communication through the direct communication link associated with the PFI is currently impossible, by the above-described methods, the SE layers <NUM> and <NUM> may notify the application layers <NUM> and <NUM> that the direct communication link associated with the PFI has been released. Then, the SE layers <NUM> and <NUM> may delete the link profile information associated with the PFI.

<FIG> illustrates an example of a data transmission procedure using a direct communication link, according to certain embodiments of the disclosure.

In various embodiments, the user equipment <NUM> may determine a layer-<NUM> ID address of the user equipment <NUM> from among link profile information to receive data on a stored direct communication link, in operation <NUM>. A data message that is transmitted on the direct communication link may have, as a destination, the layer-<NUM> ID address of the user equipment <NUM> determined in operation <NUM>.

The application layer <NUM> of the user equipment <NUM> may transmit at least one of an 'application message' generated by the application layer <NUM>, a 'PFI' representing a direct communication link on which the message is transmitted, a 'message type' representing a type of the message, a 'communication mode' (for example, Broadcast, Groupcast, Unicast, etc.) representing a communication method of the message, an 'application layer ID' of the user equipment <NUM>, an 'application layer ID' of the user equipment <NUM>, or 'QoS requirements', to the SE layer <NUM>, in operation <NUM>.

In certain embodiments, the SE layer <NUM> checks link profile information associated with the PFI, received in operation <NUM>. To transmit 'application data' received in operation <NUM>, the SE layer <NUM> may set a source layer-<NUM> ID to the currently used layer-<NUM> ID of the user equipment <NUM>, stored in the link profile associated with the PFI, and set a destination layer-<NUM> ID to the currently used layer-<NUM> ID of the user equipment <NUM>, stored in the link profile associated with the PFI, in operation <NUM>.

The SE layer <NUM> may transmit at least one of the 'application data', the 'source layer-<NUM> ID' determined in operation <NUM>, the 'destination layer-<NUM> ID' determined in operation <NUM>, or associated 'PFI' information to the SDAP layer <NUM>. The SDAP layer <NUM> of the user equipment <NUM> may transmit a message by using the received information associated with the PFI. The MAC layer <NUM> may set a logical channel ID of a MAC header for transmitting the message to a value representing a data message. A value of a logical channel ID used in a data message may be different from that of a logical channel ID used in a signaling message. The 'application data' may be transmitted to the user equipment <NUM> via the PHY layer <NUM>, in operation <NUM>.

When the MAC layer <NUM> of the user equipment <NUM> receives the 'application data', the MAC layer <NUM> may determine that the received message is a data message, based on the logical channel ID of the MAC header of the received message, and transfer the message to the SE layer <NUM> via the SDAP layer <NUM>. The SE layer <NUM> may determine whether the received message is a message for the direct communication link generated by the above-described procedure, based on the destination layer-<NUM> ID of the received message and/or the PFI information. Also, the SE layer <NUM> of the user equipment <NUM> may determine that the received message is a data message, depending on whether the message is received from the SDAP layer <NUM>.

According to various embodiments, the SE layer <NUM> may transfer the received 'application data' to the application layer <NUM>. Also, the SE layer <NUM> may transfer direct communication link information (for example, PFI, PSID, ITS-AIDs, application layer IDs of the user equipments <NUM> and <NUM>, etc.) associated with the 'application data' to the application layer <NUM>.

<FIG> illustrates an example of a procedure performed by user equipment to acquire service information from a network in an initial registration process, according to certain embodiments of the disclosure.

Referring to the non-limiting example of <FIG>, when AMF <NUM> receives a registration request message from the user equipment <NUM> through (R)AN <NUM> in operations <NUM> and <NUM>, the AMF <NUM> may request UDM <NUM> to transmit UE subscription information and acquire UE subscription information from the UDM <NUM>, in operation <NUM>. Also, the AMF <NUM> may request PCF <NUM> to transmit policy information associated with the user equipment <NUM>, in operation <NUM>.

At this time, the user equipment <NUM> may include information about functions supported by the user equipment <NUM> and/or information about a UE policy container (for example, V2X policy) in the registration request message, and transmit the resultant registration request message to the (R)AN <NUM>, in operation <NUM>. The (R)AN <NUM> may transfer the registration request message received from the user equipment <NUM> to the AMF <NUM>, in operation <NUM>. When the user equipment <NUM> supports a V2X service, information representing that the user equipment <NUM> supports the V2X service may be included in UE capability information and provided to the AMF <NUM>. Also, information representing that the user equipment <NUM> supports PC5 communication may be included in UE LTE PC5 capability information and UE NR PC5 capability information and provided to the AMF <NUM>.

According to certain embodiments, the AMF <NUM> may request the UDM <NUM> to transmit UE subscription information, in operation <NUM>. In operation <NUM>, the UDM <NUM> may transmit a UE subscription information request message to UDR <NUM>. The UE subscription information request message may include information (for example, SUPI, <NUM>-GUTI, IMSI, etc. of the user equipment <NUM>) representing the user equipment <NUM>. The UDR <NUM> may transmit a DM Query response message including the UE subscription information of the user equipment <NUM> to the UDM <NUM>. When the UDM <NUM> receives the UE subscription information, the UDM <NUM> may transmit a UE subscription response message to the AMF <NUM>. The UE subscription response message may include at least one of V2X service authentication information of the user equipment <NUM>, V2X capability of the user equipment <NUM>, PC5 LTE capability of the user equipment <NUM>, PC5 NR capability of the user equipment <NUM>, or information related to subscription of the user equipment <NUM>.

When the AMF <NUM> determines that the user equipment <NUM> supports the V2X service, based on the UE capability information received from the user equipment <NUM>, the AMF <NUM> may select PCF <NUM> that supports the V2X service. The AMF <NUM> may request the selected PCF <NUM> to transmit policy information related to the user equipment <NUM>, in operation <NUM>. In operation <NUM>, a message may include the information about the UE policy container (V2X policy) received by the AMF <NUM> from the user equipment <NUM>.

In some embodiments according to this disclosure, the PCF <NUM> may acquire a V2X service parameter that is to be applied to the user equipment <NUM> from the UDR <NUM>, by various methods. First, when the V2X service parameter needs to be updated, the UDR <NUM> may provide a V2X service parameter to the PCF <NUM>, in operation <NUM>. Also, in operation <NUM>, the PCF <NUM> may request the UDR <NUM> to transmit a V2X service parameter and acquire the V2X service parameter from the UDR <NUM>.

The V2X service parameter provided from the UDR <NUM> to the PCF <NUM> may include service policy/parameter information described in the disclosure.

Meanwhile, the PCF <NUM> may receive subscriber information of the user equipment <NUM> and information about functions supported by the user equipment <NUM>, in operation <NUM>. The AMF <NUM> may provide the UE capability information and/or UE subscription information acquired from the UDM <NUM> to the PCF <NUM>, in operation <NUM>.

The PCF <NUM> may provide information about a policy that is to be applied to the user equipment <NUM> to the AMF <NUM>, and the V2X service parameter received from the UDR <NUM> may be included in the information about the policy, in operation <NUM>.

In certain embodiments, the AMF <NUM> may include the V2X service parameter received from the PCF <NUM> in a registration accept message, and transfer the resultant registration accept message to the user equipment <NUM>, in operation <NUM>. Alternatively, the AMF <NUM> may transfer the V2X service parameter received from the PCF <NUM> to the user equipment <NUM> through a preset procedure, in operation <NUM>. The V2X service parameter, which is included in the registration accept message (operation <NUM>) or in a UE policy transfer message (operation <NUM>), may include at least one of the service policy/parameter information described in the disclosure.

<FIG> illustrates a procedure performed by a user equipment to acquire service information from a network in response to a request from the network, according to certain embodiments of the disclosure.

More specifically, <FIG> illustrates, without limitation, an example of a method performed by the user equipment <NUM> to acquire service policy/parameter information (for example, V2X service policy parameters shown in Table <NUM>) according to certain embodiments. Referring to the non-limiting example of <FIG>, the user equipment <NUM> may acquire a UE policy by using a UE configuration update procedure.

Again, with reference to the explanatory example of <FIG>, the PCF <NUM> may determine to update a UE policy, in operation <NUM>. The PCF <NUM> may have received and stored updated service policy/parameter information (for example, V2X service policy parameters shown in Table <NUM>) of the user equipment <NUM> from the UDR <NUM>, like operation <NUM> of <FIG>.

The PCF <NUM> may determine whether the UE policy needs to be updated, in an initial registration process of the user equipment <NUM> or when the network triggers updating the UE policy after initial registration of the user equipment <NUM>, as shown in <FIG>. For example, in the initial registration process, the PCF <NUM> may determine whether the UE policy needs to be updated, based on UE policy container (for example, V2X policy) information received from the AMF <NUM> and policy information (for example, included in Npcf_UEPolicyControl_Create request) associated with an access selection and PDU selection of the user equipment <NUM>. Alternatively, when an event occurs, for example, when a location of the user equipment <NUM> changes or when subscription information of the user equipment <NUM>, for example, a slice service (subscribed S-NSSAI) which the user equipment <NUM> has subscribed changes, the PCF <NUM> may determine whether the UE policy needs to change. Also, the PCF <NUM> may determine to transfer the service policy/parameter information (for example, the V2X service policy parameters shown in Table <NUM>) received from the UDR <NUM> to the user equipment <NUM>, as described above in operation <NUM> of <FIG>.

In operation <NUM>, the PCF <NUM> may transfer the service policy/parameter information (for example, the V2X service policy parameters shown in Table <NUM>) to the AMF <NUM>. When the V2X service policy parameters shown in Table <NUM> are transmitted as the service policy/parameter information, the service policy/parameter information may include at least one of the V2X service policy parameters shown in Table <NUM>. The service policy/parameter information (for example, the V2X service policy parameters shown in Table <NUM>) according to certain embodiments of the disclosure may be included in a Namf_Communication_N1N2MessageTransfer message and transmitted to the AMF <NUM>, in operation <NUM>. The Namf_Communication_N1N2MessageTransfer message may include SUPI, a UE policy container, etc..

In some embodiments, when the user equipment <NUM> has been registered in the network and is in a service receivable state, the AMF <NUM> may determine to transfer a UE policy received from the PCF <NUM> to the user equipment <NUM>, in operation <NUM>. When the user equipment <NUM> has been registered in any one of 3GPP and non-3GPP accesses, the AMF <NUM> may transfer the UE policy to the user equipment <NUM> through the access which the user equipment <NUM> has been registered in and is connected to. When the user equipment <NUM> has been registered in and is connectable to both 3GPP and non-3GPP accesses, the AMF <NUM> may select an access from among the 3GPP and non-3GPP accesses according to a local policy of the AMF <NUM> and transfer the UE policy to the user equipment <NUM> through the selected access. When the user equipment <NUM> has never been registered in or is disallowed to be connected to any one of 3GPP and non-3GPP accesses, the AMF <NUM> may notify the PCF <NUM> that transmission of the UE policy has failed (for example, through Namf_Communication_N1N2TransferFailureNotification), in operation <NUM>. When the AMF <NUM> determines to transfer the UE policy to the user equipment <NUM> through the 3GPP access and the user equipment <NUM> is in a CM-IDLE state, the AMF <NUM> may transmit a paging request message to the user equipment <NUM> to start a paging procedure (network triggered service request). When the user equipment <NUM> receives the paging request message, the user equipment <NUM> may perform a paging procedure.

In operation <NUM>, the AMF <NUM> may transfer the UE policy to the user equipment <NUM>. When the UE policy includes a V2X service, the UE policy may include at least one of the V2X service policy parameters shown in Table <NUM>.

When the user equipment <NUM> receives information about the UE policy, the user equipment <NUM> may store the information therein, and transmit a response message notifying that the information has been received to the AMF <NUM>, in operation <NUM>.

In certain embodiments, the AMF <NUM> may notify the PCF <NUM> that the service policy/parameter information (for example, the V2X service policy parameters shown in Table <NUM>) has been transmitted to the user equipment <NUM>, in operation <NUM>. At this time, a Namf_N1MessageNotify message may be used. Then, the PCF <NUM> may maintain the UE policy, or notify the UDR <NUM> of an updated UE policy.

<FIG> illustrates an example of a procedure performed by a user equipment to acquire service information from a network in response to a request from the user equipment, according to certain embodiments of the disclosure.

More specifically, <FIG> illustrates an example of a method performed by the user equipment <NUM> to acquire service policy/parameter information (for example, the V2X service policy parameters shown in Table <NUM>), according to various embodiments of this disclosure. In the non-limiting example of <FIG>, the user equipment <NUM> may trigger acquisition of a UE policy to acquire the UE policy.

Referring to the illustrative example of <FIG>, the user equipment <NUM> may transmit a message requesting a UE policy to the AMF <NUM>, in operation <NUM>. The message requesting the UE policy may be a UE policy provisioning request message, and the UE policy provisioning request message may include a UE policy container (for example, V2X policy).

Also, the AMF <NUM> may transmit a message requesting UE policy information to the PCF <NUM>, in operation <NUM>. The message requesting the UE policy information may be Npcf_UEPolicyControl_Update request, and the message may include the UE policy container (for example, the V2X policy) received from the user equipment <NUM>.

When the PCF <NUM> receives the message requesting the UE policy information, the PCF <NUM> may determine whether the UE policy needs to be updated, in operation <NUM>.

In some embodiments, operations <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> of <FIG> may be similar to the corresponding operations described above with reference to <FIG>.

For example, the PCF <NUM> may transmit information about a UE policy to the AMF <NUM>, in operation <NUM>, and the AMF <NUM> may determine to transfer the UE policy to the user equipment <NUM> and then transfer the UE policy to the user equipment <NUM>, in operations <NUM> and <NUM>. Also, the user equipment <NUM> may transmit a response message to the AMF <NUM> in response to reception of the UE policy, in operation <NUM>, and the AMF <NUM> may transmit a message about whether transmission of the UE policy is successful to the PCF <NUM>, in operation <NUM>.

A procedure performed by the user equipment <NUM> to acquire a service parameter/policy from a network, as described above with reference to <FIG>, <FIG>, and <FIG>, may be applied in the same way to other user equipment.

<FIG> illustrates, in block diagram format, an example of a configuration of a network entity according to certain embodiments of the disclosure.

Referring to the non-limiting example of <FIG>, the network entity according to certain embodiments of the disclosure may include the (R)AN <NUM>, the AMF <NUM>, the PCF <NUM>, the UDM <NUM>, and the UDR <NUM>. Also, the network entity may include eNB, MME, S-GW, P-GW, PCRF, and HSS.

Referring to the illustrative example of <FIG>, the network entity may be composed of a transceiver <NUM>, a controller <NUM>, and a storage device <NUM>. The transceiver <NUM>, the controller <NUM>, and the storage device <NUM> of the network entity may operate according to a communication method of the network entity as described above. However, components of the network entity are not limited to the above-mentioned examples. For example, the network entity may include more or less components than the above-mentioned components. Also, the transceiver <NUM>, the controller <NUM>, and the storage device <NUM> may be implemented in a form of one chip. Also, the controller <NUM> may include at least one processor.

The transceiver <NUM> is a collective name for a receiver <NUM> of the network entity and a transmitter <NUM> of the network entity, and may transmit and receive signals. Signals that are transmitted and received may include control information and data. To transmit and receive signals, the transceiver <NUM> may be composed of an RF transmitter for up-converting a frequency of a signal to be transmitted and amplifying the signal, and an RF receiver for low-noise amplifying a received signal and down-converting a frequency of the received signal. However, the RF transmitter and RF receiver are certain embodiments of the transceiver <NUM>, and components of the transceiver <NUM> are not limited to the RF transmitter and the RF receiver.

In some embodiments, the transceiver <NUM> may receive a signal through a wireless channel, output the signal to the controller <NUM>, and transmit a signal output from the controller <NUM> through the wireless channel.

The storage device <NUM> may store programs and data required for operations of the network entity. Also, the storage device <NUM> may store control information or data included in signals acquired by the network entity. The controller <NUM> may be configured with storage media, such as read only memory (ROM), random access memory (RAM), a hard disc, compact disc-read only memory (CD-ROM), and a digital versatile disc (DVD), or a combination of the storage media.

The controller <NUM> may control a series of processes such that the network entity operates according to the above-described embodiments of the disclosure. For example, the controller <NUM> may receive a control signal and a data signal through the transceiver <NUM>, and process the received control signal and data signal. Also, the controller <NUM> may transmit the processed control signal and data signal through the transceiver <NUM>.

<FIG> illustrates, in block diagram format, an example of a configuration of a user equipment according to certain embodiments of the disclosure.

More specifically, <FIG> illustrates an example of an internal structure of the user equipment <NUM> and <NUM> according to certain embodiments of the disclosure. The user equipment may include a transceiver <NUM>, a controller <NUM>, and a storage device <NUM>.

The transceiver <NUM>, the controller <NUM>, and the storage device <NUM> of the user equipment may operate according to a communication method of the user equipment as described above. However, components of the user equipment are not limited to the above-mentioned examples. For example, the user equipment may include more or less components than the above-mentioned components. Also, the transceiver <NUM>, the controller <NUM>, and the storage device <NUM> may be implemented in a form of one chip. Also, the controller <NUM> may include at least one processor.

Referring to the non-limiting example of <FIG>, transceiver <NUM> refers collectively to a receiver <NUM> of the user equipment and a transmitter <NUM> of the user equipment, and may transmit and receive signals to and from a base station. Signals that are transmitted to and received from the base station may include control information and data. To transmit and receive signals to and from the base station, the transceiver <NUM> may be composed of an RF transmitter for up-converting a frequency of a signal to be transmitted and amplifying the signal, and an RF receiver for low-noise amplifying a received signal and down-converting a frequency of the received signal. However, the RF transmitter and the RF receiver are certain embodiments of the transceiver <NUM>, and components of the transceiver <NUM> are not limited to the RF transmitter and the RF receiver.

Also, the transceiver <NUM> may receive a signal through a wireless channel, output the signal to the controller <NUM>, and transmit a signal output from the controller <NUM> through the wireless channel.

The storage device <NUM> may store programs and data required for operations of the user equipment. Also, the storage device <NUM> may store control information or data included in a signal acquired by the user equipment. The storage device <NUM> may be configured with storage media, such as ROM, RAM, a hard disc, CD-ROM, and a DVD, or a combination of the storage media.

The controller <NUM> may control a series of processes such that the user equipment operates according to the above-described embodiments of the disclosure. For example, the controller <NUM> may receive a control signal and a data signal through the transceiver <NUM>, and process the received control signal and data signal. Also, the controller <NUM> may transmit the processed control signal and data signal through the transceiver <NUM>.

Claim 1:
A method for performing unicast communication, by a first user equipment, UE (<NUM>), the method comprising:
transmitting, a direct communication request message including information about a PC5 Quality of Service, QoS, Flow for establishing a PC5 unicast link;
receiving, from a second UE (<NUM>), a response message including the information about the PC5 QoS Flow requested by the first user UE based on a result of an establishment of the PC5 unicast link; and
transmitting, to the second UE (<NUM>), a data message over the PC5 unicast link by using a profile for the PC5 unicast link,
wherein the information about PC5 QoS Flow includes a PC5 QoS Flow identifier, PFI, and a PC5 5th generation, <NUM>, QoS Indicator, PQI, and
wherein the profile comprises a Layer-<NUM> ID of the first UE (<NUM>), an application layer ID of the first UE (<NUM>), a Layer-<NUM> ID of the second UE (<NUM>), an application layer ID of the second UE (<NUM>), PC5 <NUM> QoS Indicator, PQI, or PC5 QoS Flow identifier, PFI, associated with the PQI.